[Federal Register Volume 59, Number 225 (Wednesday, November 23, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-28553]


[[Page Unknown]]

[Federal Register: November 23, 1994]


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Part II





Environmental Protection Agency





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Atrazine, Simazine and Cyanazine; Notice of Initiation of Special 
Review
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ENVIRONMENTAL PROTECTION AGENCY

[OPP-30000-60; FRL-4919-5]

 
Atrazine, Simazine and Cyanazine; Notice of Initiation of Special 
Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of Initiation of Special Review.

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SUMMARY: This notice announces that EPA is initiating a Special Review 
on pesticide products containing the herbicides atrazine, simazine and 
cyanazine. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-
triazine], simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] and 
cyanazine [2-((4-chloro-6-(ethylamino)-s-triazine-2-yl)amino)-2-
methylpropionitrile] will be collectively referred to hereafter in this 
Notice as the triazines. The triazines are widely used herbicides that 
control many broadleaf weeds and some grasses. All three are used on 
corn and may be alternatives for each other in some situations. Other 
uses include citrus, nut orchards (simazine), sugarcane and sorghum 
(atrazine) and cotton (cyanazine). Based on laboratory animal data, EPA 
has concluded that these three triazine compounds are possible human 
carcinogens and has determined that exposure to the triazines in the 
diet (food and drinking water) may pose risks of concern. EPA has also 
determined that exposure to these triazines may pose risks of concern 
to applicators and mixer/loaders who use products containing one or 
more of these chemicals and to the public who may use home lawncare 
products containing atrazine. Accordingly, the Agency has concluded 
that products containing atrazine, simazine and cyanazine meet or 
exceed the criteria for initiation of Special Review set forth in 40 
CFR 154.7(a)(2) and that a Special Review of these products is 
appropriate to determine whether additional regulatory actions are 
required.
    The Agency is concerned about the potential ecological impacts of 
ground and surface water contamination resulting from the use of 
products containing the triazines. Such contamination may have the 
potential to cause adverse effects to aquatic organisms, terrestrial 
plants and their ecosystems. The Agency is not including ecological 
effects as a trigger in this Special Review at this time. This does not 
preclude the Agency from incorporating ecological effects in this 
Special Review in the future should the consideration of additional 
information indicate that a review would be appropriate.

DATES: Comments, data and information to support or rebut the 
presumptions in this Notice and other relevant information must be 
received on or before March 23, 1995.

ADDRESSES: Submit three copies of written comments bearing the document 
number [``OPP-30000-60''], by mail to: Public Response and Program 
Resources Branch, Field Operations Division (7506C), Office of 
Pesticide Programs, Environmental Protection Agency, 401 M St., SW., 
Washington, DC 20460. In person, bring comments to Rm. 1132, CM #2, 
1921 Jefferson Davis Highway, Arlington, VA. Telephone: 703-305-5805.
    Comments and data may also be submitted electronically by any of 
three different mechanisms: by sending electronic mail (e-mail) to: 
[email protected]; by sending a ``Subscribe'' message to 
[email protected] and once subscribed, send your 
comments to OPP-30000-60; or through the EPA Electronic Bulletin Board 
by dialing 202-488-3671, enter selection ``DMAIL,'' user name ``BB--
USER'' or 919-541-4642, enter selection ``MAIL,'' user name ``BB--
USER.'' Comments and data will also be accepted on disks in WordPerfect 
in 5.1 file format or ASCII file format. All comments and data in 
electronic form should be identified by the docket number OPP-30000-60. 
Electronic comments on this Notice, but not the complete record,may be 
viewed or new comments filed online at many Federal Depository 
Libraries. Additional information on electronic submissions can be 
found in Unit XIII. of this notice.
    Information submitted in any comment concerning this Notice may be 
claimed confidential by marking any part or all of that information as 
``Confidential Business Information'' (CBI). Information so marked will 
not be disclosed except in accordance with procedures set forth in 40 
CFR part 2. A copy of the comment that does not contain CBI must be 
submitted for inclusion in the public docket. Information not claimed 
as confidential or not clearly labeled as containing CBI will be placed 
in the public file and will be disclosed publicly by EPA without 
further notice to the submitter. All non-CBI written comments will be 
available for inspection in Room 1132 at the Virginia address given 
above from 8 a.m. to 4 p.m., Monday through Friday, excluding legal 
holidays. No CBI should be submitted through e-mail.

FOR FURTHER INFORMATION CONTACT: By mail: Joseph E. Bailey, Review 
Manager, Special Review and Reregistration Division (7508W), Office of 
Pesticide Programs, Environmental Protection Agency, 401 M St., SW., 
Washington, DC 20460. Office location and telephone number: Special 
Review Branch, 3rd Floor, Crystal Station, 2800 Jefferson Davis 
Highway, Arlington, VA. Telephone: 703-308-8173. For a copy of 
documents in the public docket, to request information concerning the 
Special Review, or to request indices to the Special Review public 
docket, contact the Public Response and Program Resources Branch, Field 
Operations Division (7506C), Office of Pesticide Programs, 
Environmental Protection Agency, 401 M St., SW., Washington, DC 20460. 
Telephone: 703-305-5805.

SUPPLEMENTARY INFORMATION: This Notice describes the Special Review 
process and the basis for the Agency's decision to initiate this 
Special Review. The Notice also requests public comment on the 
triazines including information on their toxicity, possible human and 
environmental exposure and risks, the benefits of current use, and the 
risks and benefits of potential chemical and non-chemical alternatives 
to the triazines. Regarding the benefits of the triazines and their 
alternatives, the Agency is especially interested in information on use 
patterns and farming practices that are likely to result in reduced 
pesticide use and to promote solutions to weed control compatible with 
the Agency's Sustainable Agriculture and Integrated Pest Management 
goals. Procedures for submission of public comments to the Agency are 
described in Unit XIII of this Notice.
    This Notice is organized into 15 Units. Unit I describes the 
Special Review process, legal requirements for the registration of 
pesticides, and a summary of the Agency's rationale for initiating this 
Special Review of atrazine, simazine and cyanazine. Unit II summarizes 
the registration and reregistration history of the triazines as well as 
interim risk reduction measures that have been implemented. Unit III 
describes the results of animal studies submitted to the Agency to 
support continued registration of the triazine herbicides including 
discussions regarding the toxic effects of the triazines. Agency 
comments relative to registrants' responses to the preliminary 
notification to initiate this Special Review for human carcinogenic 
effects are also discussed in Unit III. Dietary exposure to the 
triazine herbicides through food is presented in Unit IV. This unit 
discusses the measurement of dietary residues of concern and estimation 
of exposure. Unit V presents the Agency's dietary risk assessment. Unit 
VI discusses the exposure to triazine herbicides through contaminated 
drinking water and compares safe drinking water standards to ground and 
surface water monitoring and detections. The environmental fate of the 
triazines is also discussed in this unit. Unit VII discusses the risk 
estimates from exposure to triazine-contaminated drinking water and the 
registrants' responses to the preliminary notification to initiate 
Special Review for such risks. Unit VIII discusses triazine exposure 
and risk estimates from non-dietary sources. Unit IX provides 
estimations of additive cancer risks from several exposure pathways and 
chemicals. Ecological exposure and effects of the triazine herbicides 
are presented in Unit X. This unit discusses ecosystem effects, the 
effects of triazines on non-target plants and animals and the Agency's 
comments relative to the registrants' responses to the preliminary 
notification to initiate Special Review for these concerns. Unit XI 
presents a use profile of the triazine herbicides and requests 
information on sustainable agriculture/IPM and reduced pesticide use. 
Unit XII discusses the requirement for registrants to submit 
information about unreasonable adverse effects associated with 
pesticide use and Unit XIII invites interested parties to comment on 
this Notice. Unit XIV summarizes materials available in the public 
docket for the triazines and Unit XV lists the references used in 
preparing this Notice.

I. Background

A. Special Review Process

    The Special Review process provides a mechanism to permit public 
participation in EPA's deliberations prior to issuance of any Notice of 
Final Determination describing the regulatory action which the 
Administrator has selected. The Special Review process is described in 
40 CFR part 154, published in the Federal Register of November 27, 1985 
(50 FR 49015). During the Special Review process the Agency: (1) 
announces and describes the basis for the Agency's finding that use of 
the pesticide meets one or more of the risk criteria set forth in 40 
CFR 154.7; (2) establishes a public docket; (3) solicits comments from 
the public regarding whether the use of a pesticide product as 
currently registered or as it is proposed to be registered satisfies 
any of the risk criteria for initiation of Special Review set forth at 
40 CFR 154.7, or whether any risks posed by the use or proposed use of 
the product that satisfy risk criteria at 40 CFR 154.7 are 
unreasonable, taking into account the economic, social, and 
environmental costs and benefits of the use of the product; and what 
regulatory action, if any, the Agency should take with respect to the 
use of the product; (4) solicits comment from the Secretary of 
Agriculture and the Scientific Advisory Panel if the Administrator 
proposes to cancel, deny, or change the classification of the 
registration of a pesticide product which is the subject of Special 
Review, or to hold a hearing under FIFRA section 6(b)(2) on whether to 
take any of those actions; (5) reviews and responds to all significant 
comments submitted in a timely manner; and (6) makes a final regulatory 
decision based on the balancing of risks and benefits associated with 
the pesticide's use.
    Issuance of this Notice means that potential adverse effects that 
may be associated with the use of pesticide products containing 
atrazine, simazine or cyanazine have been identified and will be 
examined further to determine their extent and whether, when considered 
together with the benefits of these pesticides, such risks are 
unreasonable.

B. Legal Requirements

    A pesticide product may be sold in the United States only if it is 
registered or exempt from registration under the Federal Insecticide, 
Fungicide, and Rodenticide Act (FIFRA) as amended (7 U.S.C. 136 et 
seq.). Before a product can be registered it must be shown that it can 
be used without ``unreasonable risk to man or the environment, taking 
into account the economic, social, and environmental costs and benefits 
of the use of the pesticide'' [FIFRA section 2(bb)]. The burden of 
proving that a pesticide meets this standard for registration is, at 
all times, on the proponent of initial or continued registration. If at 
any time the Agency determines that a pesticide no longer meets this 
standard, the Administrator may cancel this registration under section 
6 of FIFRA.

C. Preliminary Notification

    Prior to the public announcement of initiation of a Special Review, 
pursuant to 40 CFR 154.21, registrants of the affected pesticide are 
given preliminary notification that the Agency is considering 
initiating a Special Review. Registrants are given 30 days to respond 
in writing to dispute the validity of the Agency's conclusions or to 
present any information in response to the Agency's risk concerns 
included in this notification.
    EPA issued preliminary notifications of its intention to initiate a 
Special Review of atrazine, simazine and cyanazine to all registrants 
of these chemicals on February 8, 1994 (Refs. 1, 2, and 3). This 
notification included a brief statement of the Agency's concerns. The 
data and preliminary risk assessments triggering this Special Review 
are described in detail in subsequent units of this notice. A 
discussion of registrants' responses to the preliminary notifications 
is also included.

D. Determination to Initiate Special Review

    The Agency has determined that the estimated risks to humans posed 
by atrazine, simazine and cyanazine warrant the initiation of a Special 
Review of each of these chemicals. The Agency has also determined that 
a combined Special Review of atrazine, simazine and cyanazine is more 
appropriate than examining each individually. This determination is 
based on the following considerations: all three (1) are structurally 
related chemicals, (2) induce mammary tumors when fed to rats and are 
classified as Group C, possible human carcinogens, (3) degrade or 
metabolize to similar degradates/metabolites, (4) are generally similar 
in terms of environmental fate including relative persistence, 
leachability, run-off potential and possibly atmospheric transport, (5) 
are similar in toxicity to aquatic organisms and terrestrial plants, 
and (6) may serve as alternatives to each other for some situations.
    The Agency is concerned about the potential excess individual 
lifetime cancer risks resulting from dietary exposure to triazine-
treated food/feed commodities as well as the potential cancer risks to 
persons mixing, loading and applying products containing the triazine 
herbicides, including residential exposure to persons using lawn care 
products containing atrazine. EPA is also concerned about the potential 
risks resulting from the consumption of drinking water (from ground and 
surface water sources) contaminated with triazines and their degradates 
(metabolites), in particular the chloro degradates. Furthermore, the 
Agency is concerned about the additive impacts that may occur to 
persons exposed to more than one triazine, or through more than one 
exposure pathway.
    While the Agency is also concerned about the potential harmful 
impacts on nontarget organisms (aquatic organisms, terrestrial plants) 
and their ecosystems that may result from continued use of triazine 
herbicides, it is not, at this time, including ecological effects in 
this Special Review. The Agency's concerns regarding ecological effects 
of the triazines are discussed more fully in Unit X of this notice.

II. Regulatory History of the Triazine Herbicides

    This unit summarizes the registration and reregistration history of 
the triazines including the Data Call-In Notices (DCIs) issued for 
atrazine, simazine and cyanazine and interim risk reduction measures 
imposed during the course of the Agency's review of the triazines.

A. Atrazine

    Ciba Plant Protection (formerly Ciba-Geigy Corporation) first 
registered atrazine in 1959 and remains the lead registrant of the 
technical compound from which most end-use products are formulated. 
Ciba is responsible for generating data to support the continued 
registration of products containing this chemical. Other atrazine 
technical registrants are Oxon Italia S.P.A. and Drexel Chemical 
Company. Altogether, there are currently 36 registrants with a total of 
98 registrations for products containing atrazine.
    In 1983, EPA issued a Registration Standard for atrazine. The 
Standard noted the Agency's concern about the dietary carcinogenic risk 
from ground and surface water contamination. In 1988, EPA issued a 
preliminary notification of the Agency's intention to initiate Special 
Review to atrazine registrants based on concerns regarding the 
carcinogenic potential of atrazine and possible risks resulting from 
exposure to atrazine in the diet from treated food and from 
contaminated drinking water. Another concern surrounded the potential 
carcinogenic risks to workers exposed while mixing, loading and 
applying products containing this chemical (Ref. 4). A Data Call-In 
Notice (DCI) issued in November 1988 required submission of information 
regarding results of ground and surface water monitoring and use and 
usage data.
    In 1989, EPA notified registrants of an additional concern based on 
the results of a laboratory study showing atrazine cardiotoxicity 
(heart damage) in dogs (Ref. 5). The Agency issued a DCI requiring an 
additional study in order to further explore the findings regarding 
cardiac effects. Since that time, the Agency's concerns regarding 
cardiotoxicity have been resolved and are discussed in Unit VIII of 
this Notice.
    In 1990, the Agency accepted proposed voluntary risk reduction 
measures from Ciba which included label amendments that reduced 
application rates of atrazine and classified the chemical as a 
``Restricted Use Pesticide'' based on ground water concerns for 
agricultural uses. (Commercial, home and garden, and turf/lawn care 
uses were not restricted.) These risk reduction measures partially 
addressed EPA's ground water concerns largely by implementing measures 
to reduce the potential for point-source contamination.
    In September 1990 as part of the reregistration requirements for 
atrazine, the Agency issued a comprehensive DCI listing all remaining 
atrazine data requirements. In April 1992, EPA accepted additional 
voluntary proposals by atrazine registrants to further restrict 
atrazine use including protective measures to partially address the 
Agency's concerns regarding atrazine contamination of surface water. 
These restrictions included reducing maximum application rates, 
deleting some uses and establishing set-backs and buffer zones from 
surface water for mixing, loading and application. The registrant also 
undertook research studies to help determine the effects of set-backs 
on water quality and to further determine atrazine contamination of 
lakes and reservoirs.

B. Simazine

    Ciba first registered simazine in 1957 and currently produces 
approximately 80 to 90 percent of the technical product. There are two 
other technical registrants: Oxon Italia and Drexel. There are a total 
of 16 registrants with 38 registered products containing simazine.
    The Registration Standard for simazine, issued in March 1984, 
expressed the Agency's concern about simazine's potential for ground 
water contamination and classified it as a ``Restricted Use Pesticide'' 
based on this concern. In 1985, the Agency withdrew simazine's 
``Restricted Use'' classification and imposed both ground water 
advisory and aquatic invertebrate toxicity statements on the label.
    In August 1989, EPA issued a DCI requiring ground and surface water 
monitoring information and simazine use data. EPA issued a 
comprehensive DCI in September 1991 requiring data for reregistration 
including toxicological and residue data. In response to the DCI, Ciba 
elected not to support the aquatic uses of simazine and subsequently 
voluntarily cancelled these uses on all of its registered products 
(Ref. 6).
    In August 1993, EPA conducted a risk assessment for simazine 
algaecide products used in swimming pools, hot tubs and whirlpools, and 
concluded that water treated with simazine algaecides posed 
unacceptable cancer and non-cancer health risks to children and adults. 
After completing the risk assessment, the Agency notified the 
registrants of its concerns. Most registrants requested voluntarily the 
cancellation of their end-use products registered for such uses with no 
provisions for use of existing stocks. The cancellation order for these 
products was effective April 15, 1994 (Ref. 7). The remaining products 
for which voluntary cancellation was not requested were cancelled 
through a Notice of Intent to Cancel published in the Federal Register 
on July 7, 1994 (Ref. 8). When the final cancellation order became 
effective, further sale, distribution and use of existing stocks of 
products for these uses was prohibited.

C. Cyanazine

    In 1971, Shell Chemical Company first registered cyanazine under 
the trade name Bladex. DuPont Agricultural Products and Ciba Plant 
Protection are now the only registrants. DuPont, having the only 
technical registration, takes the lead in generating data to support 
continuing registration.
    The cyanazine Registration Standard, issued by EPA in December 
1984, classified this chemical as a ``Restricted Use Pesticide'' based 
on its detection in ground and surface water. Label statements 
regarding developmental toxicity concerns and ground and surface water 
detections were added to cyanazine labels but did not explicitly link 
the restricted use classification to these concerns. A Special Review 
of cyanazine was initiated in April 1985 based on studies showing 
developmental toxicity in two species after oral administration of the 
chemical. Estimated risks to mixer/loaders and applicators were of 
concern. Dermal developmental toxicity studies were submitted that led 
to a refinement of the risk assessment and a determination that if 
additional risk reduction measures were adopted, occupational risks 
would be partially mitigated. The Special Review was concluded in 1988 
by requiring the use of protective gloves, chemical-resistant aprons 
for mixer/loaders and closed mixing/loading systems for aerial 
application and chemigation (application of pesticides through 
irrigation). The Agency also required revised label language 
specifically linking cyanazine's ``Restricted Use'' status to its 
developmental effects. Because of the detections of cyanazine in ground 
water, the Agency determined that the ground water advisory statement 
was appropriate for cyanazine labels.
    In January 1991, EPA issued a DCI requiring information on the 
results of cyanazine ground water monitoring data to upgrade a 
monitoring study for cyanazine and one metabolite.
    In April 1992, as part of the reregistration of cyanazine, EPA 
issued a DCI requiring residue chemistry, environmental fate and 
ecological effects data. For Special Review purposes, the DCI also 
required the registrants to submit all existing data on usage, pest 
management, comparative product performance and pest resistance data. 
These data were received in October 1992.
    In 1993, the Agency approved label use restrictions proposed by the 
cyanazine registrants to partially address the Agency's ground and 
surface water concerns. Label amendments include reduced maximum 
application rates and surface water set-backs, similar to those 
previously approved for atrazine in 1992.

III. Toxicity of Atrazine, Simazine and Cyanazine

    In laboratory animal studies, all three triazines induce mammary 
tumors in one strain of one species (the female Sprague-Dawley rat) 
and, based on a weight-of-evidence approach, all three chemicals are 
classified by EPA as Group C (possible human) quantified carcinogens. 
This unit describes the results of required and voluntary toxicological 
laboratory data and other studies submitted in support of the continued 
registration of the triazine herbicides, the Agency's cancer 
classification of the triazines, findings by the EPA Cancer Peer 
Reviews and the FIFRA Scientific Advisory Panel (SAP), and the 
registrants' position regarding the Agency's cancer risk assessment.

A. Atrazine

    1. Carcinogenicity-- a. Rat study. Atrazine was administered in the 
daily diet of Sprague-Dawley rats (50/sex/dose) at doses of 0, 10, 70, 
500, or 1,000 ppm for 2 years. An additional 10 rats per sex were 
placed on control (0 ppm) and high dose (1,000 ppm) diets for 12- and 
13-month sacrifices (Ref. 9). Administration of atrazine to female rats 
was associated with a statistically significant increase in mammary 
gland fibroadenomas at 1,000 ppm; mammary gland adenocarcinomas 
[including two carcinosarcomas at the highest dose tested (HDT)] at 70, 
500, and 1,000 ppm; and total mammary gland tumor-bearing animals at 
1,000 ppm in comparison to control animals. In males, the incidence of 
testicular interstitial cell tumors was increased at the high dose in 
comparison to controls. This increase was associated with a significant 
dose-related trend driven by high dose effect; however, this 
statistically significant increase was within the historical control 
range. There was an increase in retinal degeneration and in 
centrilobular necrosis of the liver in high-dose females and an 
increase in degeneration of the rectus femoris muscle in high-dose 
males and females when compared to controls. Based on decreased body 
weight gain, the Lowest-Observed-Effect Level (LOEL) for chronic 
toxicity in males and females is 500 ppm and the No-Observed-Effect 
Level (NOEL) is 70 ppm.
    b. Mouse study. Atrazine was administered in the daily diet of CD-1 
(Charles River Laboratories) mice (60/sex/dose) at 0, 10, 300, 1,500 or 
3,000 ppm for 91 weeks (Ref. 10). Administration of atrazine to mice 
was not associated with any treatment-related changes in the incidence 
of palpable masses in male or female mice. No statistically significant 
increases in incidence were found for the following types of neoplasms: 
mammary adenocarcinomas, adrenal adenomas, pulmonary adenomas and 
malignant lymphomas. The LOEL and NOEL are determined to be 1,500 ppm 
and 300 ppm, respectively, based upon decreases in mean body weight 
gain at 91 weeks.
    c. Mutagenicity. Mutagenicity studies evaluate the potential for a 
chemical to promote genetic alterations in cells. The registrant has 
submitted five mutagenicity studies that meet EPA guideline 
requirements using atrazine. The results of these studies are negative. 
The registrant also performed an unscheduled DNA synthesis (UDS) assay 
to satisfy remaining reregistration requirements. The Agency's review 
of this study concluded that atrazine did not induce UDS in primary rat 
hepatocytes.
    d. Cancer classification. There have been three Office of Pesticide 
Programs (OPP) Carcinogenicity Peer Reviews to evaluate atrazine's 
carcinogenic potential. Two reviews were conducted prior to submission 
of this chemical to the SAP for review, and one subsequent to the SAP 
review.
    The first Carcinogenicity Peer Review Committee met in September 
1987 and concluded that the available data provided limited evidence 
for the carcinogenicity of atrazine in rats. The Committee tentatively 
classified atrazine as a Group C (possible human) carcinogen based on 
an increased incidence of mammary tumors in female Sprague-Dawley rats. 
While awaiting an acceptable mouse carcinogenicity study, the Committee 
concluded that a quantitative risk assessment should be performed due 
to the induction of mammary gland tumors and possible decreased latency 
for their appearance, and the structural similarity to other then-
registered triazine herbicides classified as Group C carcinogens (Ref. 
11).
    A second Carcinogenicity Peer Review was held in June 1988 and 
confirmed the earlier findings. This review included an evaluation of 
the mouse carcinogenicity study, in which no compound-related 
carcinogenic effects were observed (Ref. 12).
    In September 1988, the OPP Carcinogenicity Peer Review Committee 
presented its position to the SAP. The SAP agreed with the Group C 
classification but not with a Q1* approach to quantify risks (Ref. 
13). The SAP stated that the variability of the endpoint and its 
potential for secondary hormonal influence, as suggested by endocrine 
imbalance at high, but not low, doses indicated that the proposed 
quantitative risk assessment was inappropriate for this chemical.
    Shortly after the SAP presentation, a third Peer Review of atrazine 
was held and, upon reevaluation of the available data and the SAP 
comments, the OPP Carcinogenicity Peer Review Committee determined that 
the data were not appropriate for quantitative risk assessment and that 
the registrant should continue to generate data to support a hormonal 
mechanism of carcinogenicity (Ref. 13). In November 1988, the Committee 
reevaluated their decision from the third Peer Review and reverted to 
their original conclusion that a quantitative risk assessment for 
atrazine was appropriate (Ref. 14). The Committee based its decision to 
quantify the risk on a weight-of-evidence approach including the 
following considerations: (a) tumors in one species (rat) and one sex 
(female); (b) an increase in primarily malignant type tumors 
(adenocarcinomas) as contrasted with benign types; (c) both 
adenocarcinomas and the number of mammary tumor bearing animals were 
statistically increased at doses of 70, 500 and 1,000 ppm; (d) a 
possible treatment-related increase in rate of tumor appearance; and 
(e) the structure activity relationship between atrazine and other 
compounds of known carcinogenic potential. The Committee concluded that 
there were still insufficient data to support a hormonal mechanism 
theory.
    e. Determination of the Q1*. The Agency uses the linearized 
multi-stage model to extrapolate from effects seen at high doses in 
laboratory studies to predict tumor response at low doses. This model 
is based on the biological theory that a single exposure to a 
carcinogen can initiate an irreversible series of transformations in a 
single cell that will eventually lead to tumor formation. In addition, 
the linearized multi-stage model assumes that the probability of each 
transformation is linearly related to the degree of exposure (i.e., a 
threshold does not exist for carcinogenicity).
    Using this model, the cancer potency estimate in human equivalents 
(Q1*) for atrazine is 2.2  x  10-1 (mg/kg/day)-1, which 
represents the 95 percent upper confidence limit (UCL) of tumor 
induction likely to occur from a unit dose (Ref. 15).
    2. Cardiotoxicity. In 1987, atrazine registrants submitted to the 
Agency the results of a 1-year chronic dog feeding study in which the 
animals were dosed at 0, 0.5, 5 or 34 mg/kg/day. The study authors 
concluded that treatment-related effects, EKG alterations and cardiac 
lesions, were observed only at the highest dose tested. The Agency's 
review of the study resulted in the conclusion that treatment-related 
effects were seen at the mid-dose level as well as the high-dose level. 
Consequently, the Agency established a NOEL for cardiotoxicity at 0.5 
mg/kg/day. The registrant submitted additional individual animal 
information on the chronic dog study and after reviewing these data, 
the Agency agreed with the registrants that treatment-related effects 
were, in fact, seen only at the high-dose level. Accordingly, the NOEL 
was increased from 0.5 to 5.0 mg/kg/day based on EKG alterations and 
cardiac lesions (Ref. 16).

B. Simazine

    1. Carcinogenicity-- a. Rat study. Simazine technical was 
administered in the diet to groups of 50 male and female Sprague-Dawley 
(S-D) rats at 0 (control), 10, 100 or 1,000 ppm for 2 years. Additional 
groups (30-40/sex/dose) were also treated (Ref. 17). The statistically 
significant effects in the test animals are as follows:
    (1) Female S-D rats. (a) There was a statistically significant 
increase in mortality in female rats.
    (b) There was a statistically significant dose-related trend for 
mammary gland carcinomas and combined adenomas/fibromas/carcinomas; 
however, when the shortened life-span of the female rats was included 
in the statistical evaluation, the incidences of carcinoma alone at 
both the 100 and 1,000 ppm [Highest Dose Tested (HDT)] dosage groups 
were statistically significantly increased as well. The upper limit of 
the historical control incidence reported for mammary carcinoma was 
exceeded at 100 ppm, and greatly exceeded at 1,000 ppm (HDT). The 
incidence of cystic glandular hyperplasia in the mammary gland was 
statistically significantly increased at the HDT, which correlates with 
the observed high tumor incidence at that dose.
    (c) There was a statistically significant dose-related trend for 
kidney tubule adenomas; however, as in the case of the male rats, 
tumors occurred only at the HDT and the incidence was not statistically 
significant by pairwise comparison with that in the concurrent control 
group. The incidence for adenomas and/or carcinomas reported for 
historical controls was zero in all seven available studies.
    (d) There were also statistically significant dose-related trends 
for adenomas, carcinomas and combined adenoma/carcinomas of the 
pituitary gland. The incidence of pituitary gland carcinoma at 1,000 
ppm (HDT) only slightly exceeded the upper bound of the historical 
control range; it greatly exceeded the incidence reported in six out of 
the seven available studies.
    (2) Male S-D rats. (a) In male rats, there was a statistically 
significant decrease in mortality when compared to females treated with 
the same dose.
    (b) The incidence of liver tumors was significantly increased for 
carcinoma and for combined adenoma/carcinoma at 100 ppm and 1,000 ppm 
(HDT), respectively; however, these results fell within the range 
reported for historical controls.
    (c) There was also a statistically significant dose-related trend 
for kidney tubule carcinomas, and for combined adenomas/carcinomas; 
however, tumors occurred only at the HDT and neither incidence was 
statistically significant by pairwise comparison with that in the 
concurrent control.
    b. Mouse study. There is no evidence that simazine induces cancer 
in the mouse (Ref. 18).
    c. Mutagenicity. The Agency has received one acceptable 
mutagenicity study, the Salmonella assay, which was negative (Ref. 19). 
Published information reports some possibly positive mutagenicity and 
genotoxicity studies.
    d. Cancer classification. The OPP Carcinogenicity Peer Review for 
simazine, held in May 1989, concluded that simazine is a Group C 
carcinogen and that carcinogenic risks should be quantified (Ref. 20). 
The Committee considered the following to be of importance in its 
weight-of-the-evidence determination: similar structure activity 
relationship to other s-triazines, particularly atrazine; the same 
tumor type as atrazine (mammary gland tumors in the rat); malignant 
tumors in the pituitary gland; negative findings for carcinogenicity in 
the mouse; and several questionable positive mutagenicity and 
genotoxicity studies reported in published literature. The Peer Review 
Committee concluded that there were inadequate data to support a 
hormonal mechanism theory.
    e. Determination of the Q1*. Using the same model described 
earlier for estimating the Q1* for atrazine, the cancer potency 
equivalent for simazine, based on malignant mammary tumors in the rat, 
is estimated at 1.2  x  10-1 (mg/kg/day)-1 (Ref. 21). This 
represents the 95 percent UCL of tumor induction likely to occur from a 
unit dose.
    The SAP review of simazine (September, 1989), while agreeing with 
the Group C classification, did not recommend the use of a quantitative 
risk assessment. The SAP noted that certain pesticides may alter 
endocrine physiology in the rat and influence the incidence of mammary 
tumors and recommended that the Agency formulate a position on the 
regulation of chemicals with this mechanism. At a subsequent OPP Peer 
Review meeting (April, 1990), the Committee evaluated the SAP's 
recommendation and concluded that it is appropriate to use a low dose 
extrapolation model (Q1*) to quantify the carcinogenic risks of 
exposure to simazine unless the registrant provides data showing a 
hormonally mediated mechanism of action for the mammary tumor 
development (Ref. 22). Data have not been received that support a 
hormonal mechanism.

C. Cyanazine

    1. Carcinogenicity-- a. Rat study. In a combined chronic toxicity/
carcinogenicity study with cyanazine in Sprague-Dawley rats, groups of 
52 males and 52 females were fed cyanazine technical at concentrations 
of 0, 1, 5, 25, or 50 ppm in the diet for 2 years (Ref. 23). 
Additionally, 10 animals per sex per group were used as a satellite 
group for interim sacrifice at 12 months. The highest dose tested was 
considered to be adequate for carcinogenicity testing based upon 
decreased body weight gain of about 14 percent in both males and 
females in the first 3 months of the study. However, the Agency 
concluded that the animals could probably have tolerated a higher dose.
    Findings from this study include a statistically significant 
increase in malignant mammary gland tumors (adenocarcinoma and 
carcinosarcoma) in females of the 25 and 50 ppm groups, with a 
statistically significant positive trend. The incidences of malignant 
tumors were outside the historical control range of 10.1 to 22.7 
percent with an average of 17.9 percent.
    Generally, there were no non-neoplastic lesions that could be 
attributed to treatment with cyanazine, due to a lack of historical 
control data. However, three lesions were observed that have not been 
reported with other triazine herbicides. These lesions were: (i) 
granulocytic hyperplasia of bone marrow in males; (ii) extramedullary 
hematopoiesis of the spleen in males; and (iii) demyelination of the 
sciatic nerve in females.
    b. Mouse study. Findings show that dietary administration of 
cyanazine did not alter the spontaneous tumor profile in the CD-1 mouse 
(Ref. 24).
    c. Mutagenicity. There is some evidence that cyanazine has 
mutagenic activity. Of the submitted studies, cyanazine has been found 
to be positive in a mouse lymphoma assay (dose-responsive in repeat 
assays) and a UDS assay (Ref. 25). Results of another UDS assay in rat 
spermatocytes following an in vivo exposure were negative (Ref. 26).
    d. Cancer classification. In March 1991, the OPP Carcinogenicity 
Peer Review Committee evaluated the weight-of-the-evidence on 
cyanazine, with particular emphasis on its carcinogenic potential. The 
Peer Review Committee concluded that cyanazine should be classified as 
a Group C, possible human carcinogen and recommended quantification of 
human risk using a low dose extrapolation model (Q1*) (Ref. 24).
    In addition to the mammary gland tumors observed in the female 
Sprague- Dawley rat, the weight-of-the-evidence for the carcinogenic 
potential of cyanazine includes the evidence that cyanazine is 
structurally related to the other chloro-s-triazines which also induce 
mammary gland cancer in experimental animals. However, cyanazine 
differs structurally from other triazines in that the molecule has a 
cyano (nitrile) functional group in the alkyl substituent of one the 
amino groups. The presence of this highly reactive cyano group favors a 
different metabolic breakdown pathway indirectly indicating that 
cyanazine can generate a more electrophilic arylating agent than other 
chloro-s-triazines, and is consistent with the finding that cyanazine 
has a more positive genotoxicity profile than the other chloro-s-
triazines.
    e. Determination of the Q1*. Using the same model described 
earlier for estimating the Q1*s for atrazine and simazine, the 
cancer potency equivalent for cyanazine, based on development of 
adenocarcinomas and carcinosarcomas in female rats, was estimated at 
8.4  x  10-1 (mg/kg/day)-1. The Agency's Carcinogen Risk 
Assessment Verification Endeavor workgroup has increased the Q1* 
to 1.0  x  100 (mg/kg/day)-1 based on a revised oral slope 
factor. This represents the 95 percent UCL of tumor induction likely to 
occur from a unit dose (Ref. 27). The cancer classification for this 
chemical has not been presented to the SAP for review.

D. Epidemiology Data

    It is often difficult to establish a link between cause and effect 
with human epidemiological data. Such data exist for the triazines but, 
as with any data of this type, it is difficult to clearly attribute 
findings to triazine exposure. However, the Agency's review of two 
Italian field worker studies indicates a possible association between 
ovarian cancer and exposure to atrazine and simazine (Ref. 28). In 
another study, preliminary results show a correlation between atrazine 
concentrations in local areas surrounding Rathbun Lake, Iowa, and birth 
defects including heart, urogenital tract and limb reductions (Ref. 
29). Also, the Agency has reviewed published summaries of several 
cancer epidemiology studies concerning triazine use in the Midwest; 
these studies provide some evidence of an association between non-
Hodgkin's lymphoma and triazine exposure, but other explanations or 
confounding factors could account for the association (Ref. 30).
     Breast cancer in humans and triazine herbicides. Data from 
carcinogenicity studies discussed earlier show that there is an 
association between the administration of the triazines to Sprague-
Dawley rats and an increase in the incidence of mammary tumors in 
female rats. The Agency does not have data or substantial 
epidemiological evidence to definitively link the triazine pesticides 
to breast cancer in humans; however, reports have been published that 
attempt to associate breast cancer in humans to exposure to triazines 
(Refs. 31 and 32). The relevance of the mechanism for mammary 
tumorigenesis in rats to that in humans has not been documented and 
species differences have been found to exist (i.e., cells of origin, 
degree of endocrine responsiveness and metastatic potential). The 
mechanisms for tumor formation in Sprague-Dawley rats and the 
implications for causing breast cancer in humans are currently being 
investigated. Until there are data to definitively refute or support 
the possibility for certain triazines to be human mammary carcinogens, 
the Agency must regulate these compounds based on the available animal 
data and the assumption that the chemicals' potential to cause cancer 
in animals may indicate the possibility that they can cause cancer in 
humans.

E. Registrants' Response to Preliminary Notification Concerning 
Carcinogenic Risks and Agency Comments

    Responses to the Agency's preliminary notification were received 
from Ciba for atrazine and simazine, and from DuPont for cyanazine. 
Both registrants responded with regard to the Agency's concern 
regarding cancer risks associated with exposure to the triazine 
herbicides. Ciba and DuPont contend that the exact mechanism of the 
strain-specific mammary gland tumorigenesis in Sprague-Dawley rats has 
not yet been elucidated, and therefore, the association of cancer risks 
in animals to human cancer risks should not be drawn. Ciba indicated a 
willingness in its response to conduct additional research on the 
strain-specific response to atrazine and requested that the Agency 
consider additional research before reaching conclusions about the 
cancer causing potentials of atrazine and simazine. DuPont indicated in 
its response that research is currently being conducted to determine 
the mechanism of cyanazine-induced mammary gland tumors; this research 
is expected to be completed in late 1995. Both registrants requested 
that the Agency consider this additional information before reaching 
definitive conclusions about triazine cancer risks.
    In response to the above comments received from Ciba and DuPont, 
the Agency's position is that, as of the publication of this notice, 
all information available concerning the carcinogenic potential of 
atrazine, simazine and cyanazine has been considered in the Agency's 
occupational and dietary risk assessments. The Agency believes that the 
current method of quantifying cancer risks using the Q1* is 
appropriate considering the available data. To date, Dupont has 
submitted no reports or studies that show the mechanism by which 
cyanazine induces tumors. Ciba submitted a four-part voluntary hormonal 
study for atrazine to address the issue of a hormonal threshold 
mechanism. Because of the similarities between atrazine and simazine, 
the registrant contends that conclusions drawn regarding atrazine will 
also apply to simazine. The Agency has considered the information 
provided by Ciba that attempts to explain the mechanism of mammary 
tumorigenesis in rats exposed to atrazine but concludes that the data 
do not actually explain any such mechanism and therefore are not 
adequate to support a mechanism of action operating through a hormonal 
mechanism and/or threshold (Refs. 33, 34, and 35). If the registrants' 
theory that the mammary tumors seen in laboratory studies of the 
triazines is, at some future date, proven to be the result of a 
hormonal imbalance in the rat that occurs only at higher doses, the 
Agency could choose to quantify the risk using an MOE/RfD or other 
approach rather than using a Q1*. However, based on available 
data, the Q1* serves as the regulatory endpoint.
    Ciba has also hypothesized that the differences in mammary tumor 
response to atrazine by Sprague-Dawley and Fischer 344 rats can be 
attributed to differences in endocrinology between the strains. To 
address the issue of the effects being strain-specific, Ciba submitted 
a voluntary study comparing the effects of atrazine on Sprague-Dawley 
and Fischer rats. However, the Agency does not believe that the data 
provided by Ciba adequately support the theory that reproductive 
hormonal differences between the two strains accounts for the 
differences in tumor response (Ref. 33).
    An International Life Sciences Institute/Risk Science Institute 
(ILSI) workgroup is examining the suitability of the Sprague-Dawley rat 
as a model for mammary tumor formation in humans. If the Agency were to 
agree with a conclusion that the Sprague-Dawley is not an appropriate 
model, the weight-of-evidence determination for the triazines would in 
all likelihood be modified. That is, they may no longer be classified 
as possible human carcinogens. The ILSI workgroup is expected to issue 
a background report discussing the state of the science on this issue 
by the end of 1994.
    Ciba has stated that atrazine-induced endocrinologic changes in the 
female Sprague-Dawley rat are not relevant to mammary tumorigenesis in 
human females. The Agency acknowledges that not all of the risk factors 
associated with the etiology of human breast cancer are known; however, 
the Agency believes that some parallels may exist in terms of the cause 
of initiation and development of mammary tumors in female rodents and 
humans. Finally, the Agency does not want to preclude the possibility 
that the potential for tumorigenesis at other target sites may exist in 
humans as a result of exposure to the triazines. The Agency will 
consider and appropriately incorporate into its risk assessments any 
additional data provided that may better characterize the 
carcinogenicity of the triazine herbicides during the course of this 
Special Review.

IV. Triazine Dietary (Food/Feed) Exposure

    Human dietary exposure to the triazines can occur from residues 
remaining in or on treated crops including corn, orchard fruits, nuts 
and sugarcane. Dietary exposure to the triazines may also occur from 
consumption of residues in animal commodities including meat, milk, 
poultry and eggs, that result from animals having been fed triazine-
treated crops (including corn, sorghum and sugarcane). This unit 
describes the Agency's assessment of human dietary exposure to the 
triazines and the uncertainties associated with that assessment. 
Triazine dietary risks are summarized in Unit V of this notice. In 
triazine use areas, human exposure may also occur through contaminated 
drinking water from ground or surface water sources. A discussion of 
exposure and risks from triazine-contaminated drinking water is 
presented in Units VI and VII of this notice.

A. Toxic Residues of Concern

    In estimating triazine dietary risks, the Agency assumes that the 
total toxic residue of concern is the parent triazine compound plus all 
metabolites with a triazine ring, including among others, all chloro 
and hydroxy metabolites. When there are insufficient data concerning 
the toxicity of metabolites, it is the Agency's policy to make the 
conservative assumption that structurally-related metabolites are as 
toxic as the parent compound. Therefore, in estimating risks, it is 
appropriate to consider all of the triazine metabolites measured as 
well as the parent compounds.
    In plants, atrazine and simazine are metabolized to numerous 
metabolites, no one of which has yet been shown to comprise a large 
portion of the total terminal residue. Metabolic processes include N-
dealkylation and conjugation with endogenous plant components, 
particularly glutathione, and hydroxylation. Most metabolites have been 
shown to contain the intact triazine ring. In soils, atrazine and 
simazine are metabolized to dealkylated chloro metabolites and hydroxy 
analogues of the parent compounds. The dealkylated chloro metabolites 
tend to be more mobile in soils than the hydroxy parent analogues.
    In animals, data have been provided showing the animal metabolism 
of atrazine, simazine, and corn metabolites of atrazine (animals were 
fed corn which had been treated with atrazine). Higher tissue residues 
resulted from feeding atrazine or simazine, and numerous metabolites 
were identified resulting from N-dealkylation and conjugation with 
glutathione followed by modification of the glutathione moiety. In most 
cases, no single metabolite accounted for a significant percentage of 
the total residue. Exceptions to this were milk in which the di-N-
dealkylated chloro metabolite (G-28273) comprised approximately 30 
percent of the total residue for atrazine, and liver in which the 
cysteine conjugate of G-30033 comprised approximately 25 percent of the 
total residue. When corn treated with atrazine was fed to animals, much 
lower residues resulted in tissues indicating less absorption of 
metabolites than of the parent compounds.
    The metabolism of cyanazine in plants is slightly different from 
that of atrazine and simazine in that a limited number of metabolites 
(Ref. 9) comprise most of the terminal residue. Cyanazine metabolites 
result from a combination of ring hydroxylation (displacement of 
chlorine), deethylation, and oxidation of the cyano group to form 
amides and acids.
    Although the metabolism of cyanazine in animals is not yet 
adequately understood, preliminary information suggests that some of 
the same metabolites found in plants are also found in animals.

B. Anticipated Residues

    The Agency presently considers the triazine chloro metabolites to 
possess equivalent potency to the parent compounds with regard to 
carcinogenicity; however, this assumption is made from studies in which 
animals were fed parent compound only. Based on its assessment of the 
structure-activity relationship and potential carcinogenicity of all 
registered triazine compounds, EPA believes metabolites which have been 
dechlorinated may be less potent carcinogens than the parent compounds. 
An interim report on a voluntary hydroxyatrazine carcinogenicity study, 
which indicated negative findings at the end of 1 year, supports this 
hypothesis. A second interim report has been received and is currently 
being reviewed by the Agency. However, in the absence of completed 
laboratory studies on the carcinogenicity of the hydroxy metabolites, 
the Agency has relied on its equivalency policy and has made the 
assumption that all metabolites containing the triazine ring are 
equipotent as carcinogens as the parent compound when conducting its 
risk assessment. If the data in the final report are available in a 
timely fashion and indicate that the hydroxy metabolites are not 
carcinogenic, the Agency will then base its dietary exposure and cancer 
risk assessment for atrazine and simazine on the parent compounds plus 
those metabolites other than the hydroxy metabolites. As a result, the 
estimated dietary cancer risks for atrazine and simazine would appear 
to be reduced compared with current estimates. A decision has not yet 
been made by the Agency on how the results of the hydroxyatrazine 
carcinogenicity study will affect which metabolites are included in the 
risk assessment for cyanazine. The final results of the hydroxyatrazine 
study are expected in early 1995.
    1. Atrazine and simazine. For atrazine and simazine, the Agency has 
based its current dietary risk assessment on both radiolabel studies 
(both field and greenhouse) and field trials (non-radiolabel studies). 
Estimated residue levels were determined using radiolabel studies for 
corn, sorghum and animal commodities. Field trial data were used for 
all other commodities. Residue estimates from radiolabel studies 
include residues of all triazine ring containing metabolites. Residue 
estimates from field trials include either the parent compound only, or 
the parent compound plus chloro metabolites. The best available data 
currently indicate that the parent and chloro metabolites comprise only 
a small portion (less than 5 percent) of the total triazine ring 
residue in most commodities.
    These data introduce uncertainty into the dietary risk assessment 
for two major reasons. First, when field trial data are used, only a 
small portion of the total toxic residue is considered in the risk 
assessment. Because the percentage of parent plus chloro metabolites 
relative to the total triazine ring residue would be expected to vary 
somewhat from crop to crop, the percentage of the total estimated risk 
accounted for by these data is not known, but will always lead to an 
underestimate of risk when detectable residues are present. Second, no 
detectable residues were found in many commodities, particularly for 
simazine. Where there are no detectable residues, the Agency assumes 
that the residues are 1/2 the analytical method limit of detection 
(LOD). The actual residues could be far less than 1/2 the LOD leading 
to an overestimation of the risk or greater than 1/2 the LOD but less 
than the LOD leading to an underestimate.
    Since the registrants have been unable to develop analytical 
methodology which measures total triazine ring residues in non-
radiolabel field trials, radiolabel field studies currently provide the 
best data to use for risk assessment. New radiolabel field studies for 
major dietary risk contributors for both atrazine and simazine have 
been submitted to the Agency and are currently under review. 
Preliminary reviews of the data do not indicate that currently 
estimated dietary risks will change significantly.
    2. Cyanazine. The sources of information for calculating all 
anticipated residues of cyanazine in crop commodities were residue data 
from field trials and processing studies and, in some cases, data 
translated from metabolism studies (Ref. 36).
    Cyanazine metabolism studies indicate that regulated metabolites 
account for greater than 90 percent of the total triazine ring-
containing residue. Because a small set of discrete, measurable 
metabolites make up a large portion of the total triazine ring residue, 
field radiolabel studies are not necessary for cyanazine. Therefore, 
the Agency's dietary risk assessment is not expected to change based on 
submission of additional residue data.

V. Triazine Dietary (Feed/Food) Risk Assessment

 A. Dietary Cancer Risks

    Dietary (food/feed) cancer risks for the triazines were estimated 
for the overall U.S. population using the following relationship:

        Upper bound estimated carcinogenic risk = Dietary exposure 
(Anticipated Residue Contribution) x Q1*.


    It should be remembered that the Agency's procedures for 
quantifying cancer risks actually identifies a range, rather than just 
a single value. The upper boundary on that range is the risk using the 
upper 95 percent confidence limit on the toxicology data. The lower 
boundary on the range is zero. Thus, actual risk to humans may be as 
low as zero. Toxicological studies and calculation of Q1*s for 
atrazine, simazine and cyanazine were described in Unit III of this 
notice; dietary exposure assumptions were described in Unit IV of this 
notice.
    1. Atrazine cancer risk estimates. The dietary risk assessment for 
atrazine was conducted based on total triazine ring residues for corn, 
sorghum and animal commodities, and on parent, or parent and chloro 
metabolite residues for all remaining crops. This analysis resulted in 
a combined estimated upper bound carcinogenic risk of 4.4  x  10-5 
for all commodities with sugarcane being the largest single contributor 
to total atrazine risk (Ref. 37). Excluding sugarcane, the total 
atrazine carcinogenic risk is estimated to be 2.2  x  10-5. Other 
major risk contributors are milk, sweet corn, corn (other), red meat 
and eggs. The dietary cancer risk estimates for atrazine are provided 
in Table 1:

          Table 1.--Dietary Cancer Risk Estimates for Atrazine          
(FT = field trial data (parent, or parent + chloro). R = radiolabel data
                         (total triazine ring)).                        
------------------------------------------------------------------------
                   Type  Anticipated  Percent  Exposure    Upper Bound  
    Commodity      Data    Residue      Crop    (mg/kg/    Cancer Risk  
                   Used     (ppm)     Treated    day)       Estimates   
------------------------------------------------------------------------
                                                                        
Corn, sweet.....    R        0.10        60     1.4  x     3.1  x  10-6 
                                                                        
Corn, other.....    R        0.10        70     2.4  x     5.3  x  10-6 
                                                  10-5                  
                                                                        
 Eggs...........    R    0.01 (eggs,     -      5.8  x     1.3  x  10-6 
                            yolks)                10-6                  
                             0.009                                      
                           (whites)                                     
                                                                        
Guava...........    FT       0.01        10      -\1\           0       
                                                                        
Macadamia nuts..    FT       0.10        70     3.0  x    6.6  x  10-10 
                                                  10-9                  
                                                                        
 Milk...........    R       0.004        -      4.2  x     9.2  x  10-6 
                                                  10-5                  
                                                                        
Millet..........    FT       0.68        1       -\1\           0       
                                                                        
Pineapple.......    FT       0.03        20     4.0  x     9.0  x  10-8 
                                                  10-7                  
                                                                        
Poultry meat....    R       0.0006       -      3.1  x     6.8  x  10-8 
                            (meat,                10-7                  
                          fat) 0.002                                    
                            (liver)                                     
                                                                        
 Redmeat........    R      0.004 -       -      9.3  x     2.1  x  10-6 
                            0.02\2\               10-6                  
                                                                        
 Sorghum........    R        0.13        70     2.2  x     4.8  x  10-7 
                                                  10-6                  
                                                                        
Sugarcane.......    FT       0.16        80     1.0  x     2.2  x  10-5 
                                                  10-4                  
                                                                        
 Wheat..........    FT       0.02        1      2.8  x     6.2  x  10-8 
                                                  10-7                  
                                                                        
------------------------------------------------------------------------
  Total.........                                           4.4  x  10-5 
                                                                        
  Total                                                    2.2  x  10-5 
   (excluding                                                           
   sugarcane).                                                          
------------------------------------------------------------------------
\1\ Exposure values for these commodities are extremely low.            
\2\ Range of values were used for meat, liver and kidney.               

    2. Simazine cancer risk estimates. Dietary cancer risk estimates 
for simazine are based on translated atrazine data for corn and animal 
commodities. The total estimated dietary risk from all commodities is 
1.4  x  10-5 (from all registered commodities, the risk is 1.1  x  
10-5) (Ref. 38). (Note that estimates are based on half the limit 
of detection for most commodities.) The risk from simazine use on 
oranges is a major contributor to total risk, as is the risk from 
apples. Corn contributes only a small percent of the total simazine 
risk because of the low percent crop treated. The dietary cancer risk 
estimates for simazine are provided in Table 2:

          Table 2.--Dietary Cancer Risk Estimates for Simazine          
(FT = field trial data (parent, or parent + chloro). R = radiolabel data
                         (total triazine ring)).                        
------------------------------------------------------------------------
                   Type  Anticipated  Percent  Exposure    Upper Bound  
    Commodity      Data    Residue      Crop    (mg/kg/    Cancer Risk  
                   Used     (ppm)     Treated    day)       Estimates   
------------------------------------------------------------------------
                                                                        
Almonds.........  FT     0.10         45       1.3  x    1.6  x  10-8   
                                                                        
 Apples.........  FT     0.05         40       1.6  x    1.9  x  10-6   
                                                10-5                    
                                                                        
 Avocados.......  FT     0.05         30       1.9  x    2.3  x  10-8   
                                                10-7                    
                                                                        
 Bananas/Plantai  FT     0.02         10       4.7  x    5.6  x  10-8   
 ns.                                            10-7                    
                                                                        
Blueberries.....  FT     0.05         100      4.5  x    5.4  x  10-8   
                                                10-7                    
                                                                        
Caneberries.....  FT     0.05         100      7.2  x    8.6  x  10-8   
                                                10-7                    
                                                                        
Cherries........  FT     0.10         45       1.7  x    2.0  x  10-7   
                                                10-6                    
                                                                        
 Corn,sweet.....  R      0.10         5        1.2  x    1.4  x  10-7   
                                                10-6                    
                                                                        
 Corn,other.....  R      0.10         2        6.8  x    8.2  x  10-8   
                                                10-7                    
                                                                        
Cranberries.....  FT     0.05         100      1.7  x    2.0  x  10-7   
                                                10-6                    
                                                                        
 Currants.......  FT     0.05         100      2.7  x    3.2  x  10-9   
                                                10-8                    
                                                                        
 Eggs...........  R      0.0003       -        1.8  x    2.2  x  10-8   
                                                10-7                    
                                                                        
 Filberts.......  FT     0.10         100      4.0  x    4.8  x  10-9   
                                                10-8                    
                                                                        
 Grapefruit.....  FT     0.05         45       5.2  x    6.2  x  10-7   
                                                10-6                    
                                                                        
 Grapes.........  FT     0.05         35       3.9  x    4.7  x  10-7   
                                                10-6                    
                                                                        
Lemons..........  FT     0.05         50       1.0  x    1.2  x  10-7   
                                                10-6                    
                                                                        
Macadamia nuts..  FT     0.10         100      5.0  x    6.0  x 10-10   
                                                10-9                    
                                                                        
 Milk...........  R      0.00007      -        7.4  x    8.9  x  10-8   
                                                10-7                    
                                                                        
 Olives.........  FT     0.05         18       1.0  x    1.2  x  10-8   
                                                10-7                    
                                                                        
Oranges.........  FT     0.05         45       4.8  x    5.8  x  10-6   
                                                10-5                    
                                                                        
Peaches.........  FT     0.05         35       3.8  x    4.6  x  10-7   
                                                10-6                    
                                                                        
 Pears..........  FT     0.05         50       3.1  x    3.7  x  10-7   
                                                10-6                    
                                                                        
 Pecans.........  FT     0.10         10       4.8  x    5.8  x  10-9   
                                                10-8                    
                                                                        
 Plums..........  FT     0.10         12       7.4  x    8.9  x  10-8   
                                                10-7                    
                                                                        
 Poultrymeat....  R      0.0003       -        1.5  x    1.8  x  10-8   
                                                10-7                    
                                                                        
 Redmeat........  R      0.0001       -        2.3  x    2.8  x  10-8   
                                                10-7                    
                                                                        
 Strawberries...  FT     0.05         100      1.8  x    2.2  x  10-7   
                                                10-6                    
                                                                        
Walnuts.........  FT     0.10         50       2.4  x    2.9  x  10-8   
                                                10-7                    
                                                                        
------------------------------------------------------------------------
  Total                                                  1.1  x  10-5   
   (excluding                                                           
   cancelled                                                            
   uses)\1\.                                                            
                                                                        
  Total                                                  1.4  x  10-5   
   (including                                                           
   cancelled                                                            
   uses).                                                               
------------------------------------------------------------------------
\1\ Voluntarily cancelled uses include sugarcane, artichokes, asparagus 
  and fish.                                                             

    3. Cyanazine cancer risk estimates. The total estimated cyanazine 
dietary risk from all commodities is 2.9  x  10-5. (Ref. 39). The 
largest contributor of risk is corn, both through the raw agricultural 
commodity itself and through secondary residues in meat, milk, poultry 
and eggs resulting from use of corn as a feed item. DuPont has 
requested voluntary cancellation for cyanazine use on sorghum, wheat 
and fallow cropland (Ref. 40). If cancellation of these uses becomes 
final, the total dietary risk will be 2.7  x  10-5. Unlike 
atrazine and simazine, for which new residue data may refine dietary 
risks, no new residue data are necessary to refine the exposure 
estimates. The dietary cancer risk estimates for cyanazine are shown in 
Table 3:

         Table 3.-- Dietary Cancer Risk Estimates for Cyanazine         
------------------------------------------------------------------------
                    Anticipated   Percent                  Upper Bound  
    Commodity         Residue      Crop      Exposure      Cancer Risk  
                       (ppm)      Treated  (mg/kg/day)      Estimates   
------------------------------------------------------------------------
                                                                        
 Corn............  0.12          20        1.2  x  10-  1.2  x  10-5    
                                                                        
Cottonseed.......  0.09          5         9.3  x  10-  9.3  x  10-8    
                                            8                           
                                                                        
 Milk............  0.00028       -         1.2  x  10-  1.2  x  10-6    
                    (milk)                  6                           
                   0.000034                                             
                    (non-fat                                            
                    solids)                                             
                                                                        
 Poultry and eggs  0.00232 -     -         3.1  x  10-  3.1  x  10-6    
                    0.00432\2\              6                           
                                                                        
 Red meat........  0.00345 -     -         1.0  x  10-  1.0  x  10-5    
                    0.0103\1\               5                           
                                                                        
Sorghum..........  0.10          5         1.2  x  10-  1.2  x  10-7    
                                            7                           
                                                                        
 Wheat...........  0.16          1         2.3  x  10-  2.3  x  10-6    
                                            6                           
------------------------------------------------------------------------
  Total..........                                       2.9  x  10-5    
------------------------------------------------------------------------
\1\ Range of values were used for meat, meat byproducts, fat, liver and 
  kidney.                                                               
\2\ Range of values were used for meat, meat byproducts, fat, liver,    
  kidney and eggs.                                                      

VI. Triazines Exposure in Drinking Water

A. Safe Drinking Water Standards--Health Advisory Levels and Maximum 
Contaminant Levels

    To ensure public health and safety, EPA is responsible for 
establishing protective standards that limit the amount of pesticide 
contamination in drinking water. Maximum Contaminant Levels (MCL) are 
legally enforceable standards that represent the maximum permissible 
level of a contaminant in water delivered to any user of a public water 
system. Prior to establishing an MCL, the Safe Drinking Water Act 
(SDWA) requires that EPA establish a Maximum Contaminant Level Goal 
(MCLG) at the level at which no known or anticipated adverse effects on 
the health of persons occur over a lifetime of exposure and which allow 
an adequate margin of safety. Health Advisory Levels (HA) are non-
enforceable guidelines that estimate the maximum amount of a 
contaminant that can be consumed without causing adverse effects over a 
specific period of time. Both the MCLG and the HA, while non-
enforceable, are established as health-based reference points to 
provide guidance to ensure the safety of drinking water when an 
enforceable standard (MCL) is not available. The National Primary 
Drinking Water Regulations Phase II Rule requires water monitoring of 
all (60,000) community water systems and all (25,000) nontransient, 
noncommunity water systems. Quarterly samples must be taken 
consecutively each year. A water supply system is in violation if the 
running annual average at any sampling point exceeds the MCL. If the 
MCL is exceeded, water systems are required to notify the general 
public within 14 days and consumers directly within 45 days.
    The MCL for a Group C carcinogen is generally based on the 
Reference Dose (RfD) for non-carcinogenic toxic effects. An additional 
onefold to tenfold factor is applied to the RfD to account for possible 
human carcinogenic effects. The MCL is based on a cancer risk range of 
10-5 to 10-6 when non-cancer data are inadequate for deriving 
an RfD. EPA has established an MCL for atrazine at 3 g/L (or 3 
ppb) and for simazine at 4 g/L (or 4 ppb). EPA expects to 
establish an MCL for cyanazine and is also considering the possibility 
of setting MCLs for triazine degradates as well as a combination of 
triazines.
    When monitoring concentrations of contaminants in water supplies, 
the contaminant level or the annual average contaminant level is 
compared to the MCL established for that contaminant. If any single 
maximum contaminant concentration is greater than four times the MCL, 
it will automatically make the annual average of four quarterly samples 
greater than the MCL. Any water supply system reporting an average of 
any four successive quarterly samples greater than the MCL is 
considered to be out of compliance with the SDWA. The requirements of 
the SDWA do not govern decisions regarding the registrability of 
pesticides under FIFRA. However, standards such as MCLs, MCLGs, and HAs 
provide useful guidance to the Agency in identifying potential 
instances of unreasonable risks. Thus, if a pesticide is found at 
levels which exceed one of these levels, it is likely that use of that 
pesticide may exceed a Special Review trigger under the FIFRA 
regulations. Accordingly, detection of triazine residues in water at or 
above these levels is very pertinent to this Special Review.
    1. Atrazine Maximum Contaminant Level. The MCL for atrazine of 3 
g/L (3 ppb) was established in 1991 (Ref. 41). Based on a 
Q1* of 2.2  x  10-1 (mg/kg/day)-1, this MCL is 
associated with an estimated cancer risk level within the 10-5 
range for drinking water (assuming a person consumes 2 liters of water 
per day containing atrazine at 3 g/L over a 70-year lifetime) 
The MCL was calculated using the RfD of 0.005 mg/kg/day based on a NOEL 
of 0.5 mg/kg/day for decreased body weight in pups in a multi-
generation reproduction study and an additional uncertainty factor of 
10 to account for possible human carcinogenic effects. (The RfD was 
calculated using an uncertainty factor of 100: 10 for inter-species 
extrapolation and 10 for intra-species variability.) To account for 
other possible sources of exposure to atrazine, only 20 percent of the 
RfD was used to calculate the MCL.
    In 1992, the EPA RfD Committee approved an increase in the atrazine 
RfD from 0.005 mg/kg/day to 0.035 mg/kg/day, based on evidence of 
decreased body weight in a chronic rat study with a NOEL of 3.5 mg/kg/
day (Ref. 42). Based on the increase in the atrazine RfD, the 
registrant, Ciba, submitted a petition to the Administrator requesting 
a re-evaluation of the MCL and a stay on mandatory requirements 
including water monitoring (Ref. 43). The Agency considered, but has 
denied Ciba's petition to increase the MCL for atrazine. This denial 
takes into account a number of issues concerning the protection of 
public health, particularly possible cancer risks from total exposure 
to all triazines and their degradates (Ref. 44). The Agency is also 
reviewing its carcinogenicity guidelines and the Office of Water is 
revising its policy for regulating Category II chemicals which includes 
the Group C carcinogens.
    2. Simazine Maximum Contaminant Level. In July 1990, an MCL Goal 
(MCLG) of 1 g/L (1 ppb) was proposed for simazine based on a 
NOEL of 0.5 mg/kg/day for non-carcinogenic toxic effects in a 2-year 
rat study. Uncertainty factors applied included a threefold factor to 
account for a data gap with respect to the absence of adequate 
information to evaluate reproductive effects. This data gap for 
simazine was subsequently filled and since no effects were noted at the 
dose level (0.5 mg/kg/day) used to calculate the MCLG, the threefold 
safety factor was no longer required. Thus, the RfD has been increased 
from 0.002 mg/kg/day to 0.005 mg/kg/day. To account for other possible 
sources of exposure to simazine, only 20 percent of the RfD was used to 
calculate the MCL. An MCL of 4 g/L was established for 
simazine (Ref. 45). Based on a Q1* of 1.2  x  10-1 (mg/kg/
day)-1, this value is associated with an estimated cancer risk 
level within the range of 10-5 for drinking water (assuming a 
person consumes 2 liters of water per day containing simazine at 4 
g/L over a 70 year period).
    3. Cyanazine Health Advisory. EPA has not yet established an MCL 
for cyanazine. In 1988, the Agency established a lifetime Health 
Advisory (HA) for cyanazine at 10 g/L (or 10 ppb). Based on a 
rat chronic toxicity study submitted to the Agency in 1991 that 
indicated cyanazine may cause mammary tumors in female Sprague-Dawley 
rats, an additional uncertainty factor of 10 was added to the reference 
dose calculations and the HA was changed from 10 g/L to 1 
g/L, using an RfD of 0.002 mg/kg/day (decreased body weight 
gain and hyperactivity in rats). Based on a Q1* of 1  x  100 
(mg/kg/day)-1, this HA is associated with an estimated cancer risk 
level from drinking water in the 10-5 range (assuming a person 
consumes 2 liters of water per day containing cyanazine at 1 
g/L over a 70-year period). To account for other possible 
sources of exposure to cyanazine, only 20 percent of the RfD was used 
to calculate the HA. The registrant, DuPont, requested that EPA 
reconsider the change in the cyanazine HA before establishing an MCL. 
DuPont believes that the HA should be based on an 80 percent Relative 
Source Contribution rather than 20 percent as used by the Agency. (Ref. 
46).

B. Environmental Fate, Chemistry, and Transport of the Triazine 
Herbicides

    Of the three triazine herbicides, more environmental fate data are 
available for atrazine than for cyanazine or simazine simply because of 
the high level of atrazine use and the widespread research that has 
been conducted with atrazine. The parent triazine compounds as well as 
their degradates are expected to leach to ground water and to be 
transported to surface waters during runoff events that often occur 
after heavy rainfalls. Once the compounds leach into the subsoil and 
ground water, metabolism of the triazines slows considerably, because 
microbial populations are low and anaerobic conditions are not 
uncommon. Therefore, there is a potential for residues to accumulate in 
subsoils and ground water after many years of use and pose risks to 
humans consuming drinking water from contaminated ground water sources. 
When degradate residues are combined with parent residues, estimates of 
hazard to humans drinking contaminated drinking water and to aquatic 
organisms may be substantially increased.
    Atrazine, simazine and cyanazine contain a symmetrical triazine 
ring and a chloro group attached to one of the carbons in the ring. The 
other two carbons carry substituted amino groups. All three triazines 
have an ethyl group on one of the amino groups, but the substituents on 
the other amino group differ for each triazine. For atrazine the 
substituent contains an isopropyl group and for simazine it is an ethyl 
group. For cyanazine, the substituent is a nitrile group that is very 
reactive and leads to the formation of degradates containing an amide 
and/or a carboxylic acid group. The reactivity of the nitrile group is 
reflected in the faster degradation and nature of degradates of 
cyanazine when compared to atrazine and simazine.
    Based on the Agency's environmental fate data, atrazine and 
simazine are likely to be more persistent in water and in soils than 
cyanazine; however, all three triazines are mobile in a variety of 
soils. The three parent triazines persist in buffered aqueous media (pH 
5, 7, and 9) for at least 30 days indicating that abiotic hydrolysis is 
not a rapid degradation process for these chemicals. Atrazine and 
simazine are resistant to direct photolysis, but photolysis does 
contribute to the degradation of cyanazine. In soils incubated under 
aerobic conditions, atrazine and simazine have half-lives of 150 and 
110 days, respectively, whereas the half-life for cyanazine is 17 to 25 
days. Under anaerobic conditions, the half-lives are even longer (about 
2 years for atrazine and simazine and 108 days for cyanazine). The 
longer half-lives under anaerobic conditions imply that these 
herbicides may persist for an extended period of time in ground water 
and in oxygen-poor surface waters.
    Atrazine and simazine follow similar degradation pathways with both 
parent compounds forming hydroxy analogues and des-alkylated chloro 
degradates which may persist in soil and water for many months. The 
hydroxy degradates tend to be less mobile than parent or des-alkylated 
degradates. Unlike atrazine and simazine, cyanazine does not degrade to 
a hydroxy analogue, but instead produces degradates containing an amide 
and/or a carboxylic acid group formed from the nitrile group. Hydroxy 
analogues of these degradates are also formed, but to a lesser extent. 
Although cyanazine can produce chloro degradates that are common to 
atrazine and simazine, they have been shown to be only very minor 
degradation products, at least in laboratory studies.
    The parent triazine compounds as well as their degradates 
(particularly the chloro degradates) are expected to leach to ground 
water and to be transported to surface waters especially during runoff 
events that often occur after heavy rainfalls. Because metabolic 
processes tend to decrease with increasing anaerobic conditions, 
residues of parent compounds and degradates will not break down as 
rapidly and will accumulate as the compounds are transported into 
deeper soil profiles and ground water or in lakes and reservoirs.

C. Drinking Water Exposure

    Drinking water for human consumption may be obtained from both 
surface water and ground water sources. Because surface and ground 
water sources often are interconnected, contamination of one source may 
result in contamination of the other. Data which demonstrate the 
presence of the triazines in ground and surface water as well as in 
precipitation are discussed in the following sections. In general, the 
studies used in the Agency's evaluations were designed to monitor for 
specific chemicals and not to estimate populations exposed to them.
    It should be noted that EPA is also concerned about potential human 
exposure to triazine degradates resulting from consumption of drinking 
water. Although limited information is available about their occurrence 
in ground and surface water and no MCLs or HAs have been established, 
monitoring studies increasingly indicate the presence of triazine 
degradates in ground and surface waters in measurable quantities in 
many locations.
    1. Surface water--a. Surface water monitoring. The Agency has 
considered over 15 sets of data on the concentrations of triazine 
pesticides in raw and finished surface waters, most of which were 
obtained from the 12-state midwestern corn belt where the majority of 
the annual triazine use occurs. These data include field monitoring 
studies, literature reviews and data submitted under section 6(a)(2), 
the provision of FIFRA which requires registrants to inform the Agency 
of potentially adverse effects resulting from a pesticide. Information 
from 10 monitoring studies and 2 additional submissions of section 
6(a)(2) data have been the primary data used in this analysis; the 
study-specific sampling characteristics and results of these reports 
are summarized in Table 4 (Refs. 47, 48, 49, 50, and 51):

                                                  Table 4.--Summary of Surface Water Monitoring Studies                                                 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                          Percentage of 
                                                                                        Two highest    90th percentile       Median         sites with  
                                                                      Percentage of    among maximum    concentration    concentration       maximum    
      Study           Sampling         Sampling         Chemical       samples with    concentrations   of all maximum   of all maximum   concentrations
                     locations        frequency                         detections       from each      detections\1\    detections\2\     equal to or  
                                                                                          location      (g/L)   (g/L)   greater than 4
                                                                                       (g/L)                                       times MCL   
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Smith et al       30 water         Weekly April     Atrazine         80.3             22.5, 16.3       13               3.57             16.7%          
                                                                                                                                                        
                                                    Cyanazine        80.3             6.14, 5.61       4.95             0.59             13.3%          
                                                                                                                                                        
                                                    Simazine         80.3%            2.54, 2.23       1.58             0.32                            
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Baker (1988)....  8 Ohio           Almost daily     Atrazine         Not provided     245, 226         48.4             13.6             50.0%          
                   tributaries of   April thru                        for this study                                                                    
                   Lake Erie        Aug. (1982-                                                                                                         
                                    1985)                                                                                                               
                                                                                                                                                        
                                                    Cyanazine        Not provided     86.1, 23.1       14.9             3.4              40.0%          
                                                                      for this study                                                                    
                                                                                                                                                        
                                                    Simazine         Not provided     10.8, 6.93       4.95             0.78                            
                                                                      for this study                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Squillace and     6 locations in   Approx. monthly  Atrazine         91.0%            16, 16           16               7.3              25.0%          
 Engberg (USGS,    Cedar River      in May 1985                                                                                                         
 1988).            Basin            thru Nov. 1985                                                                                                      
                                                                                                                                                        
                                                    Cyanazine        35.0%            8.7, 8.1         8.6              1.8%             41.7%          
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Roux (Ciba        14 locations in  Bimonthly in     Atrazine         90.0%            30.5, 30.5       30.1             2.7              17.9%          
 Geigy, 1988).     midwestern       late spring                                                                                                         
                   corn belt        and early                                                                                                           
                   (rivers/stream   summer;                                                                                                             
                   s)               monthly at all                                                                                                      
                                    other                                                                                                               
                                    times(1986-                                                                                                         
                                    1987)                                                                                                               
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Moyer and Cross   30 locations in  4-7 samples per  Atrazine:        75.1%                                                                              
 (1988).           Illinois         location per                                                                                                        
                   (rivers/stream   year (1986-                                                                                                         
                   s)               1988)                                                                                                               
                                                                                                                                                        
                                                    1986                              16, 13           11               3.3              6.67%          
                                                                                                                                                        
                                                    1987                              24, 18           13               2.3              13.3%          
                                                                                                                                                        
                                                    1988                              39, 19           3.8              1.0              6.67%          
                                                                                                                                                        
                                                    Cyanazine:       75.1%                                                                              
                                                                                                                                                        
                                                    1986                              9, 6.2           5.7              0.66             20.0%          
                                                                                                                                                        
                                                    1987                              28, 17           11               1.5              13.3%          
                                                                                                                                                        
                                                    1988                              38, 31           5                0.45             10.0%          
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Keck (1991)       7 locations in   Daily May thru   Atrazine         Not provided     11.1, 10.7       NA               8.28             0.0%           
                   the Missouri     July (1991)                       for this study                                                                    
                   River Basin                                                                                                                          
                                                                                                                                                        
                                                    Simazine         Not provided     0.48, <          NA                < DL                           
                                                                      for this study   Detection                                                        
                                                                                       Limit (DL)                                                       
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Goolsby and       142 locations    1-3 samples per  Atrazine         98.4%            108, 71.6        27.2             3.8              26.4%          
 Thurman (1991).   across 10        year (1989)                                                                                                         
                   midwestern                                                                                                                           
                   states (rivers/                                                                                                                      
                   streams)                                                                                                                             
                                                                                                                                                        
                                                    Cyanazine        63.6%            61.2, 45.2       10.9             0.99             27.1           
                                                                                                                                                        
                                                    Simazine         46.5% (Post-     6.99, 4.88       0.95             0.07                            
                                                                      appl.)                                                                            
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Goolsby et. al.   8 locations in   Biweekly May     Atrazine         98.0%            10, 9.2          NA               5.7              0.0%           
 (1991).           Mississippi      thru Aug.;                                                                                                          
                   River Basin      Weekly Apr.                                                                                                         
                                    and Sept.thru                                                                                                       
                                    Dec. (1989)                                                                                                         
                                                                                                                                                        
                                                    Cyanazine        42.8%            7.3, 6.6         NA               4.4              50.0%          
                                                                                                                                                        
                                                    Simazine         25.6%            0.72, 0.48       NA               0.12                            
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Dupont 6(a)(2)    1 location in    Weekly May thru  Atrazine         100%                                                                               
 (1991).           West Lake,       Nov. 1991                                                                                                           
                   Iowa                                                                                                                                 
                                                                                                                                                        
                                                    Raw                               7.9, 7.3         7.18             6.2              NA             
                                                                                                                                                        
                                                    Finished                          8, 7.9           7.78             6                NA             
                                                                                                                                                        
                                                    Cyanazine        100%                                                                               
                                                                                                                                                        
                                                    Raw                               15.1, 14         13.9             11.7             NA             
                                                                                                                                                        
                                                    Finished                          15.3, 14.5       14.3             11.1             NA             
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Ciba-Geigy 6(a)2  7 Illinois       Bimonthly June   Atrazine         94.4%            68, 33           NA               22               100%           
 (1994).           water supplies   1993 thru May                                                                                                       
                   (finished        1994                                                                                                                
                   water)                                                                                                                               
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Blasland and      Summary of       Monthly 1985-    Atrazine         Not provided     11.9, 10.3       7.22             0.83             0.0%           
 Bouck (1991).     Hoover           1991                              for this study                                                                    
                   Reservoir Ohio                                                                                                                       
                   data                                                                                                                                 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Kloibel (1993)..  17 locations at  Five times       Atrazine         Not provided     4.94, 4.31       NA               4.27             NA             
                   Rathbun          April thru                        for this study                                                                    
                   Reservoir        Dec. 1990                                                                                                           
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Concentration                                       Atrazine                          4.3 - 245                         0.83 - 22                       
 Ranges (g/L).                                                                                                                                                
                                                                                                                                                        
                                                    Cyanazine                         5.6 - 86.1                        0.45 - 4.4                      
                                                                                                                                                        
                                                    Simazine                          0.48 - 7                          0.07 - 0.78                     
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Reflects the concentration at which 10 percent of the maximum detections at each sampling location are above and 90 percent are below.              
\2\ Reflects the concentration at which 50 percent of the maximum detections at each sampling location are above and 50 percent are below.              

    The Agency's major findings related to surface water can be 
summarized as follows:
    \ Of the triazine herbicides, atrazine and cyanazine were detected 
most often in both untreated and treated surface water in the 
midwestern corn belt. Simazine was detected less often and at lower 
concentrations than atrazine and cyanazine in the same region. The 
frequency of detects is more likely related to the total amount of each 
triazine used rather than a difference in their chemical and physical 
properties. The Agency has not received or reviewed any data on the 
concentrations of simazine in surface waters which drain areas of heavy 
simazine use on orchards and nut trees.
    \ Atrazine, atrazine degradates, simazine, and cyanazine residues 
often occur in the same water samples at various levels depending on 
herbicide usage in that given watershed. The cumulative effects of all 
of these triazine compounds on humans from drinking water or on aquatic 
and terrestrial ecosystems are assumed to be additive.
    \ Atrazine is detected in a high percentage of surface water 
samples collected from numerous locations within the corn belt even in 
early spring before application and in late fall and winter many months 
after application. Cyanazine, and to a lesser extent, simazine, are 
detected in a lower but still relatively high percentage of surface 
water samples collected during the first couple of months post-
application. However, unlike atrazine, they are generally not detected 
in high percentages of samples collected in early spring (pre-
application) or in fall or winter many months after application.
    \ After peaking one to several times from early May to early July, 
concentrations of atrazine and cyanazine in streams and rivers 
typically decline rapidly by late July to August to concentrations less 
than 1 g/L and remain at those levels until the application 
and post-application periods of the following spring.
    \ While most of the available data are on streams and rivers, there 
are limited data on lakes and reservoirs. Atrazine, and to a lesser 
extent cyanazine, concentrations have been reported to remain elevated 
at several g/L almost year round during some years in these 
bodies of water in the midwestern corn belt including Hoover Reservoir 
in Ohio, Rathbun Reservoir and West Lake in Iowa, Perry and Tuttle 
Creek Reservoirs in Kansas and Otter Lake in Illinois. This may be due 
at least in part to the resistance of atrazine and cyanazine to abiotic 
degradation coupled with low microbiological activities and long 
hydrological residence.
    \ Results of a number of studies of streams and rivers of the corn 
belt indicate that atrazine and cyanazine concentrations 
typicallyincrease rapidly from pre-application concentrations of less 
than 1 g/L to post-application peak concentrations of at least 
several g/L. Peak concentrations frequently exceed 10 
g/L and sometimes exceed 20 g/L. Peak concentrations 
exceeding 50 g/L appear to be rare, but peak concentrations of 
atrazine exceeding 100 g/L (up to 245 g/L) and of 
cyanazine exceeding 50 g/L (up to 86 g/L) have been 
reported.
    \ Peak concentrations generally occur between early May and early 
July often in conjunction with or shortly after the first few post-
application runoff events. In areas where tile drainage and/or 
groundwater inflow contribute substantially to the loading of atrazine 
and cyanazine to surface waters, secondary peaks may occur 
substantially after a major runoff event.
    \ Peak concentrations of triazines are generally greater in surface 
waters draining small watersheds than in those draining large 
watersheds, but triazine concentrations tend to remain elevated longer 
in surface waters draining large watersheds.
    \ Maximum and seasonal-annual time weighted mean concentrations of 
atrazine and cyanazine in surface water at the same sampling location 
often vary substantially (sometimes > 10X) from year to year depending 
in part upon the intensity, duration, and timing of post-application 
runoff events.
    \ Maximum observed concentrations of simazine in the midwestern 
corn belt are less than 4 times its MCL.
    \ For atrazine and cyanazine, many of the studies reviewed by the 
Agency have significant percentages of sampled locations with several 
month to annual means exceeding the atrazine MCL and the cyanazine HA. 
However, in many cases where a spring-summer atrazine or cyanazine mean 
exceeds the atrazine MCL or cyanazine HA, the annual mean would likely 
not exceed the health standard.
    \ Contamination of estuarine and marine waters by triazines have 
also been reported. Data show that for the period April 1, 1991, to 
March 31, 1992, approximately 1.6 percent of the atrazine, 1.6 percent 
of the cyanazine, and 2.7 percent of the simazine applied to the 
Mississippi River Basin in 1991 were transported to the Gulf of Mexico 
(Ref. 52). In a literature review of atrazine in the Chesapeake Bay and 
major rivers draining into it, a high percentage of detects (72 
percent) were reported in over 600 samples collected from 1976 to 1991, 
but only 3 concentrations were greater than 3 g/L (up to 5.9 
g/L) (Ref. 53).
    b. Triazine degradates in surface water.  Atrazine chloro 
degradates (desethyl atrazine and deisopropyl atrazine) have been 
detected in midwestern stream and river sites at concentrations of an 
order or more magnitude less than that of the parent atrazine (Ref. 
54). This study suggests that the concentration of atrazine degradates 
is generally less than 10 percent of the parent atrazine concentration 
in flowing surface water, but may be higher in lakes and reservoirs. 
Because they are not typically monitored for, the Agency has no data on 
the concentration of the degradates of either cyanazine or simazine in 
surface water. It should be noted that atrazine and simazine can 
generate two chloro degradates in common. The United States Geological 
Survey (USGS) has recently focused on detections of cyanazine in 
surface water, but the final report is not yet available.
    c. Surface water exposure.  The available data suggest that a 
number of surface source drinking water supply systems within the corn 
belt will have annual average atrazine concentrations exceeding the 
atrazine MCL of 3 g/L and/or annual average concentrations of 
cyanazine exceeding the cyanazine HA of 1 g/L. Current 
estimates may underestimate exposure because they do not include 
triazine degradates which could increase exposure levels by 10 percent; 
they may overestimate exposure in that they are annual average 
concentrations rather than annual time-weighted means. The Agency will 
be able to refine estimates of drinking water contamination with 
triazines with additional information that will be obtained from 
monitoring required by the SDWA. Similarly, the Agency will soon have 
access to data on simazine concentrations from recently-begun surface 
water monitoring in Florida and California, areas of high simazine use 
on fruits and nuts. The SWDA does not currently require water systems 
to sample and analyze for cyanazine.
    2. Ground water-- a. Ground water monitoring.  To evaluate 
potential triazine exposure through contaminated ground water, EPA has 
reviewed monitoring data that include information submitted to the 
Agency by pesticide registrants, States, the USGS as well as 
information compiled in the EPA National Pesticide Survey of Drinking 
Water Wells (NPS) and studies summarized in OPP's, Pesticides in Ground 
Water Database (PGWDB). The Agency's report, Water Resources Impact 
Analysis for the Triazine Herbicides, tentatively scheduled for release 
late in 1994, describes the studies and summarizes the findings (Ref. 
47). A brief description is provided of the major sources of data that 
the EPA has used to evaluate exposure to triazine herbicides through 
ground water contamination.
    The EPA PGWDB (1992) contains data from 153 separate studies with 
about 96 percent of the data from wells that serve as sources of 
drinking water. The NPS was a statistically designed one-time sampling 
of both larger community wells and smaller rural domestic wells 
nationwide that are currently used as sources of drinking water. It was 
designed to estimate the proportion of wells nationally that contain 
pesticides or degradates. The National Alachlor Well Water Survey 
(NAWWS) was conducted by the registrant of alachlor, Monsanto, and 
contains data from a one-time sampling of private rural wells limited 
to alachlor use areas. Estimates of atrazine residues in ground water 
can be obtained from the results of this study because alachlor and 
atrazine use areas coincide fairly closely; however, this is not the 
case with simazine and cyanazine.
    A number of States have also initiated ground water monitoring 
programs designed to evaluate the impact of pesticides and their 
degradates on ground water quality. Among these studies are Iowa's 
State-Wide Rural Well Water Survey (SWRL) and Wisconsin's Rural Well 
Survey. The Iowa study includes data on atrazine, two chloro degradates 
(desethyl atrazine and desisopropyl atrazine) and cyanazine; the 
Wisconsin study includes data on atrazine and three chloro degradates 
(desethyl atrazine, desisopropyl atrazine, and diamino chlorotriazine). 
California's Well Inventory Database is a compilation of reports of any 
pesticide testing done on well water in the state. Recently, additional 
ground water monitoring has been initiated by Ciba in 22 states. 
Preliminary reports indicate that triazine residues have been found in 
many drinking water wells nationwide (Ref. 55).
    i. Atrazine detections.  In OPP's PGWDB, atrazine is the fifth most 
often detected pesticide (following aldicarb and its metabolites, 
carbofuran, ethylene dibromide and DBCP) with detections in 32 out of 
40 states in which samples were collected. Of 1,512 wells that 
contained residues of atrazine at the time this data were compiled 
(1992), 172 wells (11 percent) were found to have concentrations that 
exceed the MCL of 3 g/L. Concentrations ranged from trace 
levels to 1,500 g/L.
    In the NPS, atrazine was the second most frequently found 
pesticide. Based on the data obtained in the NPS, EPA estimated that 
atrazine occurred in 70,800 (0.7 percent) rural domestic wells 
nationwide and in 1,570 (1.7 percent) community supply wells 
nationwide.
    Monsanto's NAWWS study was conducted to estimate the proportion of 
private, rural domestic wells in the alachlor use area that contain 
detectable concentrations of alachlor. Monsanto added four other 
herbicides as analytes, including atrazine, simazine and cyanazine. 
Atrazine was the most frequently found pesticide and was estimated to 
be present in 12 percent of wells in the alachlor use area. Monsanto 
estimated that concentrations exceeded the MCL in 0.1 percent of the 
wells in the alachlor use area. According to NAWWS data, approximately 
12 percent of the population in the alachlor use area (2.4 million 
people) is exposed to parent atrazine residues less than 0.2 
g/L (0.2 g/L was the limit of detection for atrazine 
the study). Approximately 184,000 people in this area are exposed to 
residues greater than or equal to 0.2 g/L.
    In the state studies reviewed for this Position Document, atrazine 
is one of the most frequently detected pesticides. In the Iowa SWRL, it 
was the most frequently detected pesticide (4.4 percent of rural 
private drinking water wells) and of all pesticides found, atrazine 
most often exceeded the MCL. It was estimated that atrazine (parent 
only) would be detected in 0.6 percent of wells statewide at 
concentrations that exceed the MCL. Additional detections of chloro 
triazine degradate increases the total number of wells with detections 
and would likely increase the exposure estimates.
    In Phase 1 of Wisconsin's ground water study, 218 wells in 45 
counties (almost 28 percent) were found to contain detectable (0.1 
g/L or greater) triazine residues, predominantly atrazine 
parent. Resampling of these well sites for Phase 2 indicated that 49.1 
percent of the 236 wells sampled contained atrazine parent at a level 
that exceeded the state's Preventive Action Limit of 0.35 g/L. 
The State Enforcement Standard of 3.5 g/L was exceeded in 6.4 
percent of the wells on the basis of the parent atrazine concentration 
alone.
    Atrazine is the third most frequently detected pesticide in 
California's Well Inventory Database. Confirmed detections resulting 
from routine agricultural use have reportedly been found in 119 wells. 
Residues of parent atrazine have been reported in 21 counties at 
concentrations ranging from 0.02 to 8.5 g/L.
    ii. Simazine detections.  In OPP's PGWDB, simazine was the eighth 
most often detected pesticide with detections reported in 19 out of 30 
states in which samples were collected. Of the 486 wells that contained 
residues, a total of 36 (7 percent) had concentrations that exceeded 
the MCL of 4 g/L. Concentrations ranged up to 67 g/L.
    Simazine was also one of the most commonly found pesticides in the 
NPS. Based on these data, simazine is estimated to occur in 25,000 (0.2 
percent) rural domestic wells and 1,080 (1.1 percent) community supply 
wells. The lower percentage of wells with simazine detections compared 
to those with atrazine detections is probably due to lower simazine use 
in surveyed areas since the two chemicals have a similar potential to 
reach ground water.
    Monsanto's NAWWS data on simazine estimates that approximately 
400,000 people are exposed to at least 0.03 g/L of this 
herbicide in ground water, but none at levels above the MCL of 4 
g/L. No simazine degradation products were analyzed. Monsanto 
states that this may not be a good estimate of simazine occurrence 
because the use areas of simazine and alachlor do not closely coincide.
    Simazine was the most frequently detected pesticide in California's 
Well Inventory Database. Confirmed detections resulting from routine 
agricultural use have reportedly been found in 296 wells. Residues of 
simazine parent only have been reported in 20 counties at 
concentrations ranging from 0.02 to 49.2 g/L. Simazine was not 
an analyte in the Iowa State-Wide Rural Well Water Survey or the 
Wisconsin Rural Well Survey.
    iii. Cyanazine detections.  Fewer monitoring data exist for 
cyanazine in ground water than for atrazine and simazine. In OPP's 
PGWDB, cyanazine was the fifteenth most often detected pesticide with 
detections in 15 out of 27 states in which samples were collected. Of 
155 wells that contain residues, a total of 22 (14 percent) reported 
cyanazine concentrations that exceed the HA of 1 g/L. 
Concentrations range from trace levels to 29 g/L.
    In Iowa's State-Wide Rural Well Water Survey, cyanazine was the 
fifth most frequently detected pesticide out of 27 analytes. 
Approximately 1.2 percent of rural private drinking water wells in Iowa 
were estimated to be contaminated with cyanazine parent. The maximum 
concentration detected was 0.84 g/L.
    NAWWS estimates that detectable levels of cyanazine are expected to 
occur in 0.3 percent of rural domestic wells in counties where alachlor 
is used. As in the case of simazine, these estimates may not be 
accurate because the use areas of cyanazine and alachlor do not closely 
coincide. However, using this information, OPP estimates that about 
60,000 people are exposed to at least 0.1 g/L of cyanazine in 
ground water.
    No detections of cyanazine were reported in the NPS; however, the 
minimum detection limit in that study was high (2.4 g/L) when 
compared to the HA of 1 g/L. Cyanazine was not an analyte in 
the Wisconsin study. No confirmed detections of cyanazine are reported 
in the California database.
    iv. Triazine degradates in ground water.  Only limited information 
is available on the occurrence or level of triazine degradates in 
ground water. Data on cyanazine degradates, in particular, are rarely 
sought. The most significant information on degradation products comes 
from the Iowa and Wisconsin state surveys, and from a ground water 
reconnaissance study conducted by the USGS. In contrast with the levels 
of degradates found in rivers and streams (up to 10 percent of the 
level of the parent), levels of the degradates in ground water can be 
much more significant; total triazine concentrations in ground water 
can double or triple, when chloro degradates and parent are both 
considered.
    In the Iowa State-Wide Rural Well Water Survey, two of the three 
major chloro degradates of atrazine, desethyl and desisopropyl, were 
both detected at approximately the same rate (3.5 percent and 3.4 
percent, respectively) as atrazine parent (4.4 percent). Degradates 
were commonly detected in combination with atrazine, but over half of 
the metabolite detections occurred when atrazine parent was not 
present. Because of the incidence of detections of triazine degradates, 
the percentage of wells that were found to contain triazine residues 
approximately doubled from 4.4 percent (atrazine alone) to 8 percent 
(total triazine residues) when comparing parent only detects with 
parent plus degradate detects.
    In the Wisconsin Rural Well Survey, degradates accounted for 67 
percent of total triazine residues detected. Almost 92 percent of wells 
that were resampled in Phase 2 of the study contained a combination of 
parent and degradate residues. Two atrazine chloro degradates, desethyl 
atrazine and di-amino s-triazine, were found with approximately the 
same frequency as atrazine parent (83 to 88 percent) at concentrations 
of up to 8.8 and 9.9 g/L, respectively. A third chloro 
degradate, desisopropyl atrazine, was detected less frequently (60.6 
percent) and at lower concentrations (0.1 to 2.6 g/L). As 
discussed previously, atrazine parent concentrations exceeded the 
Wisconsin enforcement standard in 6.4 percent of the wells, while 
combined concentrations of atrazine and chloro degradates exceeded the 
State Enforcement Standard (ES) in 29 percent of the wells resampled, 
or 3 percent more than the number of original wells exceeding the ES.
    Preliminary results of a recent USGS study of herbicides and 
nitrates in near-surface aquifers in the midcontinental United States 
indicate that the degradate desethyl atrazine was the most frequently 
reported compound (18.1 percent of wells), followed by atrazine (17.4 
percent) and desisopropyl atrazine (5.7 percent) (Ref. 56). 
Approximately 25 percent more wells contained total triazine residues 
than wells in which atrazine parent alone was found. No analyses were 
done for the third chloro degradate, diamino chlorotriazine. This study 
differs from the NPS and NAWWS studies in that it was not statistically 
designed, and it sampled ground water, not just ground water used as a 
source of drinking water.
    b. Ground water exposure.  The triazine chemicals have had a major 
impact on ground-water resources. In atrazine use areas, ground-water 
contamination is widespread at levels well below the Maximum 
Contaminant Level, but occurs at higher levels in localized areas. This 
contamination may persist for decades or longer in ground water. With 
currently available analytical methodology, atrazine is the most 
frequently detected pesticide in ground water in the midwestern United 
States, including Nebraska, Iowa, Illinois, Indiana, Minnesota, and 
Wisconsin. The Pesticides in Ground Water Database 1992 Report 
indicates that atrazine has been detected in 32 out of the 40 states 
that have reported monitoring data. EPA estimates that, based on 
results of the NPS and the NAWWS, between 2 million and 3 million 
people using ground water as their primary drinking water source are 
exposed to atrazine at average concentrations of at least 0.2 
g/L. S-triazine herbicides other than atrazine (simazine, 
cyanazine, and prometon) have had much less cumulative impact on 
ground-water quality than atrazine, probably because they are less 
intensively used. Another important factor leading to this conclusion 
is that they have not been as extensively studied. Recent information 
also indicates that at least three triazine metabolites can constitute 
a significant component of the total residues in ground water. The 
impact on ground water quality and human health from these metabolites 
is still unknown, but there is the potential that these compounds could 
contribute to the toxic effects on humans and the environment. In 
addition, since surface water and shallow ground water are often 
hydraulically connected, rivers contaminated with s-triazines can 
contaminate nearby wells; alternatively, contaminated ground water can 
supply water to rivers.
    The USGS has recently focused on detections of cyanazine degradates 
in groundwater. However, a final report has not yet been published. 
According to the NAWWS data, approximately 12 percent of the population 
in the alachlor use area (2.4 million people) are exposed to atrazine 
residues of less than 0.2 g/L. Approximately 184,000 people in 
this area are exposed to residues greater than or equal to 0.2 
g/L (limit of detection for the study). Monsanto's NAWWS data 
on simazine estimates approximately 400,000 people are exposed to at 
least 0.03 g/L of this herbicide in ground water, but none at 
levels above the MCL of 4 g/L. Using the NAWWS data on 
cyanazine, OPP estimates that about 60,000 people are exposed to at 
least 0.1 g/L in ground water. As mentioned earlier, the 
exposure numbers for simazine and cyanazine may not be good estimates 
because the use areas of these chemicals do not closely coincide with 
those of alachlor.

D. Triazines in Precipitation

    Triazines are also found in precipitation. These residues in 
rainfall are expected to be additive to the triazine residues already 
found in surface water. Therefore ``triazine rainfall'' reaching 
surface water may also increase the levels of contamination in drinking 
water. Triazine herbicides have been detected in precipitation samples 
in a study of 23 states in the upper midwest and northeast United 
States (Ref. 57). Atrazine was the most frequently detected herbicide, 
followed by alachlor, desethyl atrazine and metolachlor. Concentrations 
ranging from 1 to 3 g/L of atrazine were measured in a few 
samples; however, most precipitation-weighted herbicide concentrations 
varied between 0.2 and 0.4 g/L in May and June samples. 
Another study conducted in Isle Royale National Park, Michigan, showed 
that rainwater samples contained atrazine residues ranging from trace 
levels to 0.05 g/L (Ref. 58). Atrazine residues ranging up to 
1.5 g/L were also detected in rainwater in the rural areas of 
Iowa with large variations in the pesticide content of precipitation 
between individual storms (Ref. 59).

VII. Risks from Exposure to Triazine-Contaminated Drinking Water

 A. Risk Estimates at the Maximum Contaminant Level/Health Advisory

    Triazines pose a potential drinking water risk to exposed human 
populations. Monitoring data indicate that there is extensive triazine 
contamination of ground water and surface water used for drinking 
purposes. The estimates of the levels of exposure would be expected to 
increase if complete monitoring data were available for the degradates. 
The extent of the human population exposed to these contaminated 
drinking water sources (i.e. exposure greater than the MCL) is not 
certain. However, 29 million people use surface water for drinking 
water in 11 corn belt states with the remainder of the people using 
ground water for drinking purposes.
    As stated previously, EPA has established MCLs for atrazine and 
simazine at 3 g/L and 4 g/L, respectively, and an HA 
for cyanazine at 1 g/L. When establishing MCLs, the Agency 
assumes a Relative Source Contribution (RSC) of at least 20 percent in 
the drinking water and 80 percent from other sources. (The RSC refers 
to the percentage of the RfD allocated to a particular source, i.e. 
water contributes 20 percent of the total exposure). As yet, there are 
no MCLs established for triazine degradates and estimates of risk from 
consuming water contaminated by the triazine herbicides do not include 
the potential risks associated with exposure to their degradates. 
Estimating carcinogenic risk from drinking water assumes lifetime (70 
years) consumption of 2 liters of water per day by a 70 kg human.
    Based on the cancer potency (Q1*) and exposure (i.e. 2 L/day) 
assumptions used to calculate carcinogenic risk, exposure to atrazine 
in drinking water at the MCL (3 g/L) results in an upper bound 
excess carcinogenic risk of 1.9  x  10-5. Exposure to simazine in 
drinking water at the MCL (4 g/L) results in an upper bound 
excess carcinogenic risk of is 1  x  10-5. Exposure to cyanazine 
in drinking water at the HA (1 g/L) results in an upper bound 
excess carcinogenic risk of 2.5  x  10-5.

 B. Risk Estimates Based on Monitoring Data

    Drinking water risks from ground or surface water sources are not 
typically included in EPA's estimates of dietary (food) risk due to 
lack of adequate monitoring data, fluctuations in exposure levels 
geographically, poor consumption information and other factors. Since 
there are surface and ground water monitoring data available for the 
triazines, these data have been used to develop more realistic 
estimates of triazine drinking water risks to exposed populations. 
However, data are not available to allow OPP to determine the number of 
people who actually consume surface water contaminated with the 
triazines.
    1. Surface water sources.  To estimate risks from surface water 
exposure, two monitoring studies were considered. The first study 
monitored for 15 pesticides, including atrazine and cyanazine, in 
surface water at 30 stations (flowing water) in Illinois (Ref. 60). 
Because the Illinois study did not sample for simazine, a second study 
that was conducted primarily to provide information on the occurrence 
of alachlor in drinking water, but also monitored atrazine, simazine 
and cyanazine, was used to determine the average time-weighted mean 
concentrations (TWMC)(averages over 30 supplies) for simazine. The 
average TWMCs are 0.84 g/L for atrazine, 0.23 g/L for 
simazine and 0.43 g/L for cyanazine; the high end or 90th 
percentile TWMCs are 1.88 g/L for atrazine, 0.31 g/L 
for simazine and 1.66 g/L for cyanazine. The Agency estimated 
exposure for mean tapwater intake and 90th percentile consumption using 
values of 22.6 and 39.8 g water/kg bwt/day, respectively. Consumption 
values were derived from USDA's 1977-78 Nationwide Food Consumption 
Survey (Ref. 61). The use of this water consumption value may 
underestimate risk because it does not include consumption of 
``commercial water'' added during the manufacture and processing of 
products such as sodas and beer. The excess individual lifetime cancer 
risk estimates from both average and 90th percentile exposure to 
triazines in surface water are shown in Table 5 (Ref. 60):

     Table 5.--Excess Individual Lifetime Cancer Risk Estimates from    
                      Consumption of Surface Water                      
------------------------------------------------------------------------
                              Mean Exposure           90th Percentile   
------------------------------------------------------------------------
Atrazine...............  4.2  x  10-6             1.6  x  10-5          
                                                                        
Simazine...............  6.2  x  10-7             1.5  x  10-6          
                                                                        
Cyanazine..............  9.7  x  10-6             6.6  x  10-5          
------------------------------------------------------------------------

    It is important to note that these cancer risk estimates for 
surface water are geographically restricted and do not apply to the 
entire U.S. population, but are representative values for individuals 
residing in the corn belt region. In other regions of the country where 
the triazines are not used, there will be no risk from drinking water, 
while in some areas (i.e., Florida and Central Valley of California) 
simazine concentrations are likely to be much higher than in the corn 
belt.
    2. Ground water sources.  To estimate risks from ground water 
exposure, detections from NAWWS monitoring data were used with the same 
drinking water intake assumptions discussed earlier for surface water. 
The NAWWS data provide the best estimates of exposure based on 
currently available ground water information.
    Assuming Q1*s of 2.2  x  10-1 (mg/kg/day)-1 for 
atrazine; 1.2  x  10-1 (mg/kg/day)-1 for simazine; and 1.0 
x  100 (mg/kg/day)-1 for cyanazine, the upper bound excess 
individual lifetime cancer risk estimates for the triazines are 
provided in Table 6 (Ref. 62):

     Table 6.--Excess Individual Lifetime Cancer Risk Estimates from    
                       Consumption of Ground Water                      
------------------------------------------------------------------------
                              Mean Exposure           90th Percentile   
------------------------------------------------------------------------
Atrazine...............  9.9  x  10-7             1.8  x  10-6          
                                                                        
Simazine...............  8.1  x  10-8             1.4  x  10-7          
                                                                        
Cyanazine..............  2.3  x  10-6             4.0  x  10-6          
------------------------------------------------------------------------

    Because these estimates apply only to those individuals consuming 
triazine-containing drinking water from rural domestic wells in the 
alachlor use area, they may underestimate risk. In addition, because 
the NAWWS residue values used to estimate risk are lower bound 
estimates, cancer risks may be higher. Furthermore, it is important to 
note that the exposure estimates from the NAWWS data do not include 
triazine degradates; their inclusion could increase the exposure 
estimates, thereby increasing the risk.

C. Registrants' Responses to Preliminary Notification Concerning 
Drinking Water Risks and Agency Comments

    Ciba and DuPont have responded to the Agency's preliminary 
notification of possible Special Review for drinking water risks 
associated with triazine contamination. The registrants' responses and 
the Agency's comments are detailed below.
    In DuPont's response, it stated that a voluntary cyanazine exposure 
reduction program proposed in 1993 was developed in close cooperation 
with the Agency and that the program is aimed at reducing ground and 
surface water contamination with cyanazine from agricultural point and 
non-point sources. DuPont developed the risk reduction program to 
address Agency concerns regarding surface water detections in 
exceedance of the current cyanazine HA of 1 g/L resulting from 
rainfall run-off events. DuPont contends that their program will 
significantly reduce runoff contamination of drinking water supplies. A 
report on the effectiveness of the risk reduction measures will be 
available to the Agency in the Fall of 1994.
    The Agency believes that DuPont's 1993 proposal was a positive step 
towards reducing ground and surface water contamination, but clearly 
indicated when accepting the proposal that these were considered to be 
only interim measures. The Agency has no information that shows that 
these risk reduction measures have reduced contamination to an 
acceptable level. During the Special Review, the Agency will evaluate 
the report that DuPont will submit and determine the effectiveness of 
these measures and whether or not additional measures will be 
necessary.
    The Agency remains concerned about the occurrence of cyanazine at 
exceedances of its HA in ground water. Both ground water and surface 
water supplies serve as sources for drinking water and are often 
interconnected. Data from the Pesticides in Ground Water Data Base 
estimated that approximately 57 surface water systems exceeded the HA 
compared with about 360 ground water systems. Although some ground 
water systems may be influenced by surface water, and may show lower 
levels of cyanazine as a result of mitigation measures, the Agency is 
still concerned that most ground water systems would remain vulnerable 
to contamination from cyanazine leaching. Furthermore, the contribution 
of cyanazine degradates to the total triazine residue in both surface 
and groundwater is still unknown because no published data on cyanazine 
degradate monitoring are available at the present time. However, the 
Agency is aware of ongoing research by the USGS in this area and will 
evaluate all new information as it becomes available (Ref. 56).
    DuPont also stated that it believed that the HA for cyanazine 
should be increased and has petitioned the Office of Water to 
reevaluate and raise the HA based upon an 80 percent Relative Source 
Contribution (RSC) from water.
    In April 1994, the Agency denied DuPont's request to change the RSC 
used in deriving the cyanazine HA. The Agency believes that it is 
prudent to use a 20 percent RSC value rather than 80 percent for the 
following reasons: (1) the Agency RSC workgroup is still discussing 
multimedia exposure and the allocation of the RSC from drinking water, 
and (2) there are uncertainties associated with the contribution of 
total triazines and their degradates to the total exposure. (Ref. 63).
    Ciba contends that, based on currently available health and safety 
data for atrazine and simazine, no significant health risks result from 
exposure to contaminated drinking water. Ciba also states that it has 
designed and implemented a 22-state ground water monitoring program to 
define the presence of atrazine, simazine and their chloro metabolites 
in water. Ciba believes that most water supply systems can comply with 
a MCL of 3 g/L for atrazine but that some systems will be 
above the standard at some times during any given year, and in some 
cases, on an annual basis. Ciba petitioned the Agency to reevaluate the 
MCL for atrazine based on the revised RfD established for atrazine on 
October 1, 1993, citing the increase in the RfD as the basis. Ciba also 
claimed an inconsistency in the Agency's views regarding water systems 
exceeding the established MCL. Ciba recounted that during a meeting 
with the Office of Water, there was no urgency on behalf of the Agency 
to revise the MCL because water utilities nationally would not have a 
problem complying with the current standard. Ciba points out that, on 
the other hand, the Agency has issued the preliminary notification 
because of concern for compliance with the current standard. For 
simazine, Ciba believes the current monitoring data demonstrate that 
widespread contamination of drinking water does not exist and that 
results of the ongoing program will support this position.
    The Agency has reviewed Ciba's position and has a number of 
comments. The positions of the Office of Water and the Office of 
Pesticide Programs are not inconsistent in that both are concerned 
about health risks from drinking water and both offices have chosen to 
take a position most protective of public health. As discussed 
previously, the Agency recently has denied Ciba's request to revise the 
MCL for atrazine. For both atrazine and simazine, the Agency is 
initiating this Special Review because of data that show levels of 
ground and surface water contamination which could result in 
unacceptable drinking water risks.

VIII. Triazine Non-dietary Exposure and Risks

    Occupational and residential exposure to atrazine, simazine and 
cyanazine varies depending on several factors including the use 
pattern, the specific crop treated, the personal protective equipment 
used, whether the person exposed is a grower or commercial applicator, 
whether an individual is mixing, loading or applying the pesticide, and 
whether the individual is a homeowner. In general, a grower is likely 
to be involved in all aspects of the pesticide treatment, while in 
commercial operations, different individuals usually mix/load and apply 
the pesticide. The total exposure to growers is generally lower than 
for commercial operators because growers usually treat fewer acres, use 
less pounds of active ingredient per season and are exposed for only a 
few days each year. The Agency has estimated only dermal exposure to 
workers and residents because inhalation exposure for the triazines is 
negligible in comparison to dermal exposure.

A. Triazine Non-Dietary Exposure and Carcinogenicity Risk

    1. Exposure assumptions-- a. Atrazine. The Agency has estimated 
exposure for mixer/loaders; aerial, ground boom and handheld spray gun 
applicators; and aerial flaggers at representative use sites. The use 
sites chosen because they represent major atrazine uses are corn, 
sorghum and sugarcane. Macadamia nut orchards are selected to represent 
handheld spray gun applications and turf uses are selected to represent 
home gardener uses.
    In determining the exposure estimates for the representative 
atrazine use sites, it is assumed that all pesticide handlers wear long 
sleeve shirts, long pants and boots, but only mixer/loaders wear 
chemical resistant gloves. Exposure to mixer/loaders is estimated 
assuming an open pour system or a closed loading system. For ground 
boom application to corn, sorghum and sugarcane, exposure to 
applicators using an open cab is distinguished from that of applicators 
using closed cab equipment; however, currently registered labels do not 
require closed loading nor closed cab tractors. Atrazine exposure 
estimates for agricultural crops were derived using an application rate 
of 1.0 or 1.2 lbs. active ingredient/acre.
    The Agency has considered a recent exposure study submitted by Ciba 
that monitored dermal and inhalation exposure to mixer/loaders and 
applicators during commercial and homeowner turf treatment using 
products containing atrazine. This exposure monitoring study 
characterized exposure for four different scenarios, including: (1) 
home use lawn treatment using a ``Push Cyclone Spreader''; (2) home use 
lawn treatment with a hand cyclone spreader; (3) mixing/loading and 
``handgun'' application to client lawns by a pest control operator 
(PCO); and (4) mixing/loading and ``handgun'' spray application to a 
golf course by a golf course caretaker. To estimate exposure to 
homeowners and PCO/golf course caretakers, application rates of 3.17 
and 3.96 lbs. active ingredient/acre, respectively, were used.
    b. Simazine. Dermal exposure estimates for agricultural workers 
exposed to simazine are based on the same assumptions as those 
discussed above for atrazine. Exposure estimates from open or closed 
loading systems, open or closed cab tractors, or from use of aerial 
equipment are used to estimate the cancer risk from occupational 
exposure. Simazine estimates are based on an application rate of 1.1 
lb. active ingredient/acre.
    c. Cyanazine. The Agency has derived exposure estimates for corn, 
the predominant cyanazine use site. These estimates are based on 
assessments completed for atrazine because both pesticides are used and 
applied to field corn in a similar fashion. The cyanazine estimates are 
based on an application rate of cyanazine alone at 3 lb. active 
ingredient/acre.
    2. Non-dietary cancer risk estimates.  Excess individual lifetime 
cancer risk estimates for agricultural workers are calculated from the 
following equation:
    Cancer risk = Q1*  x  LADE  x  percent dermal absorption 
where LADE = exposurex (mg/kg/yr)/365 days/yr  x  35/70 = lifetime 
average daily exposure.


For home use and commercial application to turf, the cancer risks are 
estimated from the following equation:
    Cancer risk = Q1*  x  LADD (lifetime average daily dose) 
where LADD = (Dermal LADE  x  percent dermal absorption) + 
Inhalation LADE

    a. Atrazine.  To estimate cancer risk for atrazine, the Agency used 
a dermal absorption value of 26.9 percent derived from a rat dermal 
absorption study. Based on this dermal absorption value, upper bound 
excess individual lifetime cancer risks range from 10-6 to 
10-2 for individuals involved in the agricultural application of 
atrazine as shown in Table 7 (Ref. 64):

                 Table 7.-- Atrazine - Occupational Cancer Risk Estimates for Agricultural Crops                
----------------------------------------------------------------------------------------------------------------
   Crop/Application                           Daily Exposure (mg/kg/  Annual Exposure (mg/   Upper Bound Cancer 
        Method                 Tasks                   day)                  kg/yr)           Risk Estimates\1\ 
----------------------------------------------------------------------------------------------------------------
                                                                                                                
Corn - Grower/Ground   M/L - open             1.78                   3.11                   2.5  x  10-4        
                                                                                                                
                       M/L - closed           0.029                  0.05                   4.0  x  10-6        
                                                                                                                
                       A - open               4.96                   8.65                   7.1  x  10-4        
                                                                                                                
                       A - closed             0.19                   0.34                   2.8  x  10-5        
                                                                                                                
                       M/L/A - open/open      6.74                   11.76                  9.5  x  10-4        
                                                                                                                
                       M/L/A - open/closed    1.97                   3.45                   2.8  x  10-4        
                                                                                                                
                       M/L/A - closed/open    4.99                   8.70                   7.1  x  10-4        
                                                                                                                
                       M/L/A -closed/closed   0.22                   0.39                   3.1  x  10-5        
                                                                                                                
                                                                                                                
Corn - Commercial/     M/L - open             6.38                   95.66                  7.7  x  10-3        
 Ground boom.                                                                                                   
                                                                                                                
                       M/L - closed           0.10                   1.54                   1.2  x  10-4        
                                                                                                                
                       A - open               5.15                   77.76                  6.5  x  10-3        
                                                                                                                
                       A - closed             0.20                   3.02                   2.4  x  10-4        
                                                                                                                
                       M/L/A - open/open      11.53                  173.42                 1.4  x  10-2        
                                                                                                                
                       M/L/A - open/closed    6.58                   98.68                  8.3  x  10-3        
                                                                                                                
                       M/L/A - closed/open    5.25                   79.30                  6.5  x  10-3        
                                                                                                                
                       M/L/A -closed/closed   0.30                   4.56                   3.7  x  10-4        
                                                                                                                
                                                                                                                
Corn - Commercial/     M/L - closed           0.099                  1.49                   1.2  x  10-4        
 Aerial.                                                                                                        
                                                                                                                
                       Pilot                  0.008                  0.12                   9.5  x  10-6        
                                                                                                                
                       Flagger                0.044                  0.66                   5.3  x  10-5        
                                                                                                                
Sorghum - Grower/      M/L - open             1.42                   1.79                   1.5  x  10-4        
 Ground boom \2\.                                                                                               
                                                                                                                
                       M/L - closed           0.023                  0.029                  2.4  x  10-6        
                                                                                                                
                       A - open               4.8                    5.99                   4.9  x  10-4        
                                                                                                                
                       A - closed             0.19                   0.23                   1.9  x  10-5        
                                                                                                                
                       M/L/A - open/open      6.22                   7.78                   6.5  x  10-4        
                                                                                                                
                       M/L/A - open/closed    1.61                   2.02                   1.7  x  10-4        
                                                                                                                
                       M/L/A - closed/open    4.82                   6.02                    4.9  x  10-4       
                                                                                                                
                       M/L/A - closed/closed  0.21                   0.26                   2.1  x  10-5        
                                                                                                                
                                                                                                                
Sugarcane - Ground     M/L - open             5.31                   80.0                   6.5  x  10-3        
 boom (Commercial).                                                                                             
                                                                                                                
                       M/L - closed           0.086                  1.3                    1.1  x  10-4        
                                                                                                                
                       A - open               4.29                   64.2                   5.2  x  10-3        
                                                                                                                
                       A - closed             0.17                   2.49                   2.0  x  10-4        
                                                                                                                
                       M/L/A - open/open      9.60                   144.2                  1.2  x  10-2        
                                                                                                                
                       M/L/A - open/closed    5.48                   82.49                  6.5  x  10-3        
                                                                                                                
                       M/L/A - closed/open    4.38                   65.5                   5.3  x  10-3        
                                                                                                                
                       M/L/A -closed/closed   0.26                   3.79                   3.1  x  10-4        
                                                                                                                
                                                                                                                
Sugarcane - Aerial...  M/L - closed           0.094                  2.8                    2.2  x  10-4        
                                                                                                                
                       Pilot                  0.007                  0.22                   1.8  x  10-5        
                                                                                                                
                       Flagger                0.041                  1.23                   1.0  x  10-4        
                                                                                                                
Macadamia nuts -       M/L - open             0.79                   3.2                    2.6  x  10-4        
 Handheld sprayer\2\.                                                                                           
                                                                                                                
                       A - single applicator  16.84                  67.4                   5.4  x  10-3        
                                                                                                                
                       A - split application  16.84                  33.7                   2.7  x  10-3        
                                                                                                                
                       M/L/A - single app.    17.63                  70.6                   5.7  x  10-3        
                                                                                                                
                       M/L/A - split app.     17.63                  36.9                   3.0  x  10-3        
----------------------------------------------------------------------------------------------------------------
\1\ Based on potential dermal absorption of 26.9%.                                                              
\2\ Exposure is only 1 to 4 days per year.                                                                      

    Because growers are likely to be involved in mixing, loading and 
applying atrazine, it is important to consider the total exposure from 
all of these operations. In commercial operations, different 
individuals are likely to mix/load and apply atrazine. The occupational 
cancer risk estimates for atrazine are primarily dependent upon whether 
mixer/loaders use open versus closed loading systems, and whether 
application occurs from open versus closed cab equipment. As stated 
previously, currently approved labels do not require closed equipment. 
In addition, cancer risk estimates vary depending on the method of 
application.
    The Agency estimates the upper bound excess individual lifetime 
cancer risks for residents loading and applying atrazine to home lawns 
to range from 10-6 to 10-5. For PCO treatment of turf, cancer 
risk estimates are in the range of 10-3 for mixer/loaders, 
applicators and mixer/loader/applicators. The cancer risk estimates for 
treatment of golf courses by golf course caretakers are 10-5 for 
both mixer/loaders and applicators, while the cancer risk to those 
performing all three tasks is 10-4. These estimates are shown in 
Table 8 (Ref. 65):

                                         Table 8.-- Atrazine - Occupational Cancer Risk Estimates for Turf/Lawns                                        
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Daily Dermal        Daily Inhalation        Annual Dermal       Annual Inhalation                       
 Application Method           Tasks          Exposure\1\ (mg/kg/   Exposure\1\ (mg/kg/   Exposure\1\(mg/kg/    Exposure\1\(mg/kg/    Upper Bound Cancer 
                                                    day)                  day)                   yr)                   yr)            Risk Estimates\2\ 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
Home Use - Push       M/L/A                 0.045                 0.0002                0.045                 0.0002                3.7  x  10-6        
                                                                                                                                                        
Home Use - Hand       M/L/A                 0.285                 0.0008                0.285                 0.0008                2.4  x  10-5        
 Cyclone Spreader\3\.                                                                                                                                   
                                                                                                                                                        
PCO - Handgun         M/L                   0.217                 0.016                 11.593                0.878                 1.2  x  10-3        
 Application.                                                                                                                                           
                                                                                                                                                        
                      A                     0.282                 0.004                 15.106                0.211                 1.3  x  10-3        
                                                                                                                                                        
                      M/L/A                 0.499                 0.020                 26.699                1.088                 2.5  x  10-3        
                                                                                                                                                        
Golf Course -         M/L                   0.739                 0.056                 0.739                 0.056                 7.7  x  10-5        
 Handgun Application.                                                                                                                                   
                                                                                                                                                        
                      A                     1.702                 0.069                 1.702                 0.069                 1.6  x  10-4        
                                                                                                                                                        
                      M/L/A                 8.311                 0.336                 8.311                 0.336                 7.8  x  10-4        
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Assumes 70 kg worker.                                                                                                                               
\2\ Based on potential dermal absorption of 26.9% and potential inhalation absorption of 100%.                                                          
\3\ Gloves were not worn.                                                                                                                               

    b. Simazine.  To estimate cancer risk for simazine, the Agency used 
a dermal absorption value of 32 percent derived from a rat dermal 
absorption study. Based on this dermal absorption value, estimated 
upper bound cancer risks to individuals involved in the application of 
simazine to field corn range from 10-6 to 10-2 (Ref. 64). 
Occupational cancer risks are comparable to those of atrazine because 
both pesticides are applied using similar equipment and application 
rates. The occupational cancer risks from exposure to simazine are 
provided in Table 9:

                             Table 9.--Simazine - Occupational Cancer Risk Estimates                            
----------------------------------------------------------------------------------------------------------------
   Crop/Application                           Daily Exposure (mg/kg/  Annual Exposure (mg/   Upper Bound Cancer 
        Method                 Tasks                   day)                  kg/yr)           Risk Estimates\1\ 
----------------------------------------------------------------------------------------------------------------
Corn - Grower/Ground   M/L - open             1.61                   2.86                   1.5  x  10-4        
 boom                                                                                                           
                                                                                                                
                       M/L - closed           0.026                  0.046                  2.4  x  10-6        
                                                                                                                
                       A - open               4.54                   7.93                   4.2  x  10-4        
                                                                                                                
                       A - closed             0.18                   0.31                   1.6  x  10-5        
                                                                                                                
                       M/L/A - open/open      6.15                   10.79                  5.8  x  10-4        
                                                                                                                
                       M/L/A - open/closed    1.79                   3.17                   1.7  x  10-4        
                                                                                                                
                       M/L/A - closed/open    4.57                   7.98                   4.2  x  10-4        
                                                                                                                
                       M/L/A - closed/closed  0.21                   0.36                   1.9  x  10-5        
                                                                                                                
Corn - Commercial/     M/L - open             5.85                   87.7                   4.6  x  10-3        
 Ground boom                                                                                                    
                                                                                                                
                       M/L - closed           0.094                  1.41                   7.3  x  10-5        
                                                                                                                
                       A - open               4.72                   71.3                   3.8  x  10-3        
                                                                                                                
                       A - closed             0.18                   2.77                   1.5  x  10-4        
                                                                                                                
                       M/L/A - open/open      10.57                  159.0                  8.4  x  10-3        
                                                                                                                
                       M/L/A - open/closed    6.03                   90.47                  4.6  x  10-3        
                                                                                                                
                       M/L/A - closed/open    4.81                   72.71                  3.8  x  10-3        
                                                                                                                
                       M/L/A - closed/closed  0.27                   4.18                   2.2  x  10-4        
                                                                                                                
Corn - Commercial/     M/L - closed           0.091                  1.36                   7.3  x  10-5        
 Aerial                                                                                                         
                                                                                                                
                       Pilot                  0.007                  0.11                   5.8  x  10-6        
                                                                                                                
                       Flagger                0.04                   0.60                   3.1  x  10-5        
----------------------------------------------------------------------------------------------------------------
\1\ Based on potential dermal absorption of 32%.                                                                

    c. Cyanazine.  To estimate cancer risk for cyanazine, the Agency 
used a dermal absorption value of 2 percent derived from a rat dermal 
absorption study. Based on this dermal absorption value, the 
occupational cancer risks to individuals involved in the application of 
cyanazine to field corn range from 10-6 to 10-2 (Ref. 64). 
The results are comparable to those of atrazine and simazine and are 
provided in Table 10:

                            Table 10.--Cyanazine - Occupational Cancer Risk Estimates                           
----------------------------------------------------------------------------------------------------------------
   Crop/Application                           Daily Exposure mg/kg/   Annual Exposure (mg/   Upper Bound Cancer 
        Method                 Tasks                   day)                  kg/yr)           Risk Estimates\1\ 
----------------------------------------------------------------------------------------------------------------
Corn - Grower/Ground   M/L - open             4.46                   7.77                   2.2  x  10-4        
 boom.                                                                                                          
                                                                                                                
                       M/L - closed           0.072                  0.13                   3.6  x  10-6        
                                                                                                                
                       A - open               12.39                  21.63                  6.0  x  10-4        
                                                                                                                
                       A - closed             0.48                   0.84                   2.4  x  10-5        
                                                                                                                
                       M/L/A - open/open      16.85                  29.40                  8.0  x  10-4        
                                                                                                                
                       M/L/A - open/closed    4.94                   8.61                   2.4  x  10-4        
                                                                                                                
                       M/L/A - closed/open    12.46                  21.76                  6.0  x  10-4        
                                                                                                                
                       M/L/A - closed/closed  0.55                   0.97                   2.6  x  10-5        
                                                                                                                
Corn - Commercial/     M/L - open             15.94                  239.1                  6.6  x  10-3        
 Ground boom.                                                                                                   
                                                                                                                
                       M/L - closed           0.26                   3.86                   1.1  x  10-4        
                                                                                                                
                       A - open               12.88                  194.4                  5.4  x  10-3        
                                                                                                                
                       A - closed             0.50                   7.54                   2.0  x  10-4        
                                                                                                                
                       M/L/A - open/open      28.82                  433.50                 1.2  x  10-2        
                                                                                                                
                       M/L/A - open/closed    16.44                  246.64                 6.8  x  10-3        
                                                                                                                
                       M/L/A - closed/open    13.14                  198.26                 5.4  x  10-3        
                                                                                                                
                       M/L/A - closed/closed  0.76                   11.40                  3.2  x  10-4        
                                                                                                                
Corn - Commercial/     M/L - closed           0.25                   3.71                   1.0  x  10-4        
 Aerial.                                                                                                        
                                                                                                                
                       Pilot                  0.02                   0.30                   8.2  x  10-6        
                                                                                                                
                       Flagger                0.11                   1.65                   4.6  x  10-5        
----------------------------------------------------------------------------------------------------------------
\1\ Based on potential dermal absorption of 2%.                                                                 

B. Triazine Non-Dietary Exposure and Cardiotoxicity Risks (Atrazine 
Only)

    1. Cardiotoxicity risk exposure assumptions.  As discussed in Unit 
III of this notice, the Agency used a NOEL of 5.0 mg/kg/day to 
characterize cardiotoxicity risk to workers from exposure to atrazine. 
Because this NOEL was derived from an oral feeding study, and the 
primary route of exposure to workers is via dermal contact, the Agency 
accommodated for this difference by using kinetic data which allowed a 
comparison of peak blood concentration data from oral toxicity and 
dermal absorption studies (Ref. 66). Comparing the blood concentrations 
following administration by different routes represents a more accurate 
method of assessing exposure and ultimately risk because it accounts 
for absorption, distribution and excretion, which can be different 
depending upon the route of administration. The data showed that 
maximum blood levels following dermal exposure were several orders of 
magnitude lower than those following ingestion of the chemical at 
similar doses.
    2. Margins of exposure (MOE) for cardiotoxic risk.  The Agency 
generally considers an MOE of 100 or greater to be adequately 
protective for workers. The Agency calculated MOE values by comparing 
daily exposure estimates against a NOEL of 5.0 mg/kg/day for 
cardiotoxicity. Using the revised NOEL of 5.0 mg/kg/day and the kinetic 
data, the MOEs for workers functioning as mixer/loaders and applicators 
are greater than 100 for all use scenarios, thereby alleviating the 
Agency's concerns of cardiotoxic effects for workers exposed to 
atrazine (Ref. 65).

IX. Combining Cancer Risks Across Exposure Pathways and Chemicals

    In June, 1993, the National Academy of Sciences released a report 
entitled ``Pesticides in the Diets of Infants and Children.'' The 
report, requested in 1988 by the U.S. Congress, made specific 
recommendations for changes in pesticides regulatory practice, 
including the area of risk assessment methodology. The Academy 
recommended that EPA evaluate potential risk from exposure to several 
pesticides with common mechanisms of action and/or exposure via 
multiple routes. These recommendations are, in fact, long standing 
directives of the law governing the tolerance setting process, as set 
forth in the Federal Food, Drug and Cosmetic Act. Section 408 of the 
Act specifically states that appropriate consideration is to be given 
``...to other ways in which a consumer might be affected by the same 
pesticide chemical or by related substances that are poisonous or 
deleterious...'' The Agency is implementing these recommendations using 
a phased-in approach, beginning with a few case studies for which 
information already exists to establish a commonality of mechanism. For 
assessments involving multiple routes of exposure, case studies will 
also be conducted. These studies will evaluate potential cumulative 
exposures resulting from a single chemical which has many food uses as 
well as domestic and commercial non-food uses. An example of the 
ultimate implementation of these recommendations would be a case study 
for a chemical class which appears to share a commonality of mechanism 
of action and is registered for use on many food, nonfood and 
residential sites. In the coming years, substantial discussion, 
research and generation of data will be needed to reach agreement both 
on what is meant by ``common mechanisms of action'' and appropriate 
methods for estimating risks to subpopulations from multiple routes of 
exposure.
    The Agency has selected the triazines as a candidate for one of the 
case studies. This selection was based on a number of factors. This 
group of pesticides presents an example where a plausible argument can 
be made for supporting the assumption that atrazine, simazine and 
cyanazine operate through a common mechanism of action for the 
carcinogenic response observed in the rat mammary gland. In addition, 
treatment of various commodities with atrazine, simazine and cyanazine 
results in the presence of common metabolites, some of which are of 
toxicological significance. From an exposure standpoint, the triazines 
are used on a variety of food and non-food sites, both in an 
occupational and residential setting. Additionally, the potential 
exists for exposure through consumption of contaminated ground and 
surface water. Therefore, the triazines present an example where the 
Agency can address pesticides with commonality of mechanism as well as 
exposure through multiple pathways.
    The Agency believes the triazines case study presents an 
opportunity for public participation in the development of improved 
risk assessment methodologies. The Agency acknowledges that there are 
several ways of approaching this problem and the triazines case study 
presents but one way. Moreover, the Agency welcomes input from 
interested parties on this approach and sees this as an initial step in 
implementing the Academy's recommendations.

A. Combining Estimated Cancer Risks Across Exposure Pathways

    In the past, for the most part, the Agency has evaluated the human 
health risks for various exposure pathways separately and has not 
combined these risk estimates to obtain a composite risk estimate for a 
single pesticide. In reality, individuals may be routinely exposed to a 
given pesticide through several exposure pathways. For the triazine 
herbicides, potential exposure pathways include consumption of residues 
in food, consumption of contaminated drinking water, application to 
agricultural commodities by both growers and commercial operators, 
application around the home and post-application exposure. Rather than 
quantifying exposure for every possible use, the Agency normally 
focuses on the primary uses and those likely to result in the highest 
exposure. This step has been performed for the triazines, with exposure 
and upper bound excess individual lifetime cancer risk estimates 
contained in Tables 1 through 3 and Tables 5 through 10 of this notice.
    After identifying all possible exposure pathways, the next step is 
to identify reasonable exposure pathway combinations that have the 
potential to expose the same individual or subpopulation. For example, 
drinking water may only be contaminated in a localized portion of the 
country and it would be inappropriate to assume the entire population 
of the United States is exposed via this pathway. It is also useful to 
estimate the number of individuals potentially exposed via each 
pathway. In determining whether it is reasonable to combine exposure 
pathways, the temporal relationship of those exposures is relatively 
unimportant as long as exposure levels are low because the multistage 
model for carcinogens predicts additivity at low levels of exposure. In 
other words, each additional exposure increases an individual's cancer 
risk incrementally, if one is assuming a multistage model of 
carcinogenesis. The possible combination of exposure pathways can be 
extremely complex for pesticides with many uses, such as the triazine 
herbicides. Some individuals or subpopulations will be exposed through 
several pathways while others may be exposed via a single pathway 
(e.g., dietary only). One approach is to develop a matrix of reasonable 
exposure combinations for each triazine herbicide, with each 
combination depicting exposure to a subset of the overall population. 
However, as a first step, the excess individual lifetime cancer risks 
should be provided for each exposure pathway and also assuming exposure 
via all reasonable pathways. The remaining exposure pathway 
combinations will fall within this range. In many instances, one 
pathway will contribute the majority of exposure, with the other 
pathways adding a negligible amount to the overall exposure and risk. 
One possible combination of exposure pathways for the triazines is 
outlined in the following Table 11:

 Table 11.--Triazines - Upper Bound Cancer Risk Estimates Across Several
                            Exposure Pathways                           
------------------------------------------------------------------------
 Exposure Pathway       Atrazine          Simazine          Cyanazine   
------------------------------------------------------------------------
                                                                        
Dietary..........  4.4  x  10-5       1.1  x  10-5      2.9  x  10-5    
                                                                        
                                                                        
Drinking Water\1\  4.2  x  10-6       6.2  x  10-7      9.7  x  10-6    
                                                                        
                                                                        
Occupational\2\..  7.7  x  10-3       4.6  x  10-3      6.6  x  10-3    
                                                                        
                                                                        
Residential\3\...  2.4  x  10-5       N/A               N/A             
------------------------------------------------------------------------
                                                                        
Total............  7.8  x  10-3       4.6  x  10-3      6.6  x  10-3    
------------------------------------------------------------------------
\1\ Derived from surface water.                                         
\2\ Commercial application to corn using ground boom equipment-mixer/   
  loader.                                                               
\3\ Lawn treatment by homeowner using hand cyclone spreader.            

    Accounting for other exposure pathways, such as post-application 
exposure, would increase the risk estimates for each pesticide. This 
example applies to an individual who consumes contaminated drinking 
water from a surface water source only, is employed as a commercial 
operator, and applies an atrazine product to their lawn. The number of 
individuals who are exposed via any combination of pathways likely will 
be less than for each pathway by itself. The results of the analysis 
indicate that one exposure pathway ``drives'' the overall risk when 
combining exposure across several pathways. This result will routinely 
occur when estimating cancer risks to those involved in the commercial 
application of these triazine pesticides.

B. Combining Cancer Risks Across Chemicals

    Individuals are routinely exposed to more than one pesticide 
simultaneously in a given day, use season and/or year, either through 
dietary or occupational/residential routes of exposure. For example, 
individuals often apply pesticides which are tank-mixed or pre-packaged 
with other active ingredients. Moreover, multiple chemical exposures 
from foods may occur through consumption of a single commodity with 
multiple pesticide residues and/or consumption of multiple commodities 
with single or multiple pesticide residues. However, EPA risk 
assessments have traditionally focussed on exposure from a single 
pesticide which may underestimate risks in many instances. The Academy 
highlighted this issue by recommending that EPA combine exposures of 
pesticides with common mechanisms of action. The Agency's Risk 
Assessment Guidelines for Chemical Mixtures, published in 1986, provide 
useful guidance for assessing the overall potential for cancer and 
noncancer effects posed by multiple chemicals. These guidelines can 
also be applied to the case of simultaneous exposures to several 
chemicals from a variety of sources and by more than one exposure 
pathway. The Agency is currently in the process of revising these 
guidelines.
    The Agency's Risk Assessment Guidelines for Chemical Mixtures do 
not recommend a single approach to assess risks from multiple chemical 
exposures. Rather, the Guidelines outline a risk assessment approach 
based on the quality of the toxicity database. The ideal approach for 
assessing risks from chemical mixtures is to obtain toxicological data 
on the mixture itself. However, as is the case with most chemical 
mixtures, very little if any toxicity data are available for pesticide 
mixtures. Some data are available on pesticide products containing 
mixtures, but these data are usually limited to acute toxicity data and 
are not useful for assessing subchronic and chronic risks or, even 
acute risk, in general. Fortunately, a wealth of toxicity data is 
available on single active ingredients or the various components of a 
pesticide mixture. In the absence of data on the potential interaction 
among the components, the Guidelines for Chemical Mixtures recommend 
additive models for risk assessment of chemical mixtures. This is a 
default assumption that assumes independence of action by the 
pesticides involved (i.e., that there are not synergistic or 
antagonistic chemical interactions and that all chemicals produce the 
same effect). The Guidelines state further that ``...Based on current 
information, additivity assumptions are expected to yield generally 
neutral risk estimates (i.e., neither conservative nor lenient) and are 
plausible for component compounds that induce similar types of effects 
at the same sites of action.''
    The Guidelines state that for carcinogens where linearity of the 
individual carcinogenic dose-response relationships has been assumed, 
it is appropriate to simply sum excess individual lifetime cancer risks 
to account for exposure to several compounds. This approach assumes 
independence of action and additivity among the several carcinogens. 
For pesticides, summing excess cancer risks is relevant for both 
product mixtures and situations where an individual may be exposed to 
several pesticides, as long as exposures are small.
    In the case of the triazines, a plausible argument can be made for 
supporting the assumption that atrazine, simazine and cyanazine operate 
through a common mechanism of action in inducing mammary tumors in the 
rat. Of the currently registered triazine herbicides, these three 
pesticides are all members of the 2-chloro-4,6-bis-(alkylamino)-s-
triazine subgroup. They also produce the same tumor type - malignant 
mammary gland tumors in the Sprague-Dawley rat. The Agency conducted a 
Structure Activity Relationship Analysis concluding that this subgroup 
of triazines poses a hazard of equal concern, both qualitatively and 
quantitatively, when compared with one another. The Agency has assumed 
additivity and that no synergistic or antagonistic interaction between 
these three chemicals exists, which is consistent with the Guidelines 
on Chemical Mixtures when chemical-specific data do not exist or 
contradict this assumption. Therefore, the Agency used a simple 
additive approach to estimate lifetime excess cancer risks for 
concurrent and sequential exposure to atrazine, simazine and cyanazine.
    Each exposure pathway discussed earlier in this notice has been 
addressed for atrazine, simazine and cyanazine. Additional exposure 
pathways do exist (e.g., post-application exposure) which the Agency 
may evaluate in the future. The dietary risk estimates for each 
commodity and a total across all commodities, characterize the total 
dietary risk from commodities treated with atrazine, simazine and 
cyanazine as provided in Table 12:

                           Table 12.--Total Dietary Cancer Risk Estimates - Triazines                           
----------------------------------------------------------------------------------------------------------------
      Commodity               Atrazine               Simazine              Cyanazine                Total       
----------------------------------------------------------------------------------------------------------------
                                                                                                                
                                                                                                                
Almonds..............  0                      1.5  x  10-8           0                      1.5  x  10-8        
                                                                                                                
                                                                                                                
Apples...............  0                      1.9  x  10-6           0                      1.9  x  10-6        
                                                                                                                
                                                                                                                
Avocados.............  0                      2.3  x  10-8           0                      2.3  x  10-8        
                                                                                                                
                                                                                                                
Bananas/Plantains....  0                      5.6  x  10-8           0                      5.6  x  10-8        
                                                                                                                
                                                                                                                
Blueberries..........  0                      5.4  x  10-8           0                      5.4  x  10-8        
                                                                                                                
                                                                                                                
Caneberries..........  0                      8.6  x  10-8           0                      8.6  x  10-8        
                                                                                                                
                                                                                                                
Cherries.............  0                      2.0  x  10-7           0                      2.0  x  10-7        
                                                                                                                
                                                                                                                
 Corn, sweet.........  3.1  x  10-6           1.4  x  10-7           5.7  x  10-6           8.9  x  10-6        
                                                                                                                
                                                                                                                
 Corn, other.........  5.2  x  10-6           8.2  x  10-8           6.2  x  10-6           1.1  x  10-5        
                                                                                                                
                                                                                                                
Cottonseed...........  0                      0                      9.3  x  10-8           9.3  x  10-8        
                                                                                                                
                                                                                                                
Cranberries..........  0                      2.0  x  10-7           0                      2.0  x  10-7        
                                                                                                                
                                                                                                                
Currants.............  0                      3.2  x  10-9           0                      3.2  x  10-9        
                                                                                                                
                                                                                                                
 Eggs................  1.3  x  10-6           2.1  x  10-8           1.7  x  10-6           3.0  x  10-6        
                                                                                                                
                                                                                                                
Filberts.............  0                      4.8  x  10-9            0                     4.8  x  10-9        
                                                                                                                
                                                                                                                
Grapefruit...........  0                      6.2  x  10-7           0                      6.2  x  10-7        
                                                                                                                
                                                                                                                
Grapes...............  0                      4.7  x  10-7           0                      4.7  x  10-7        
                                                                                                                
                                                                                                                
 Guava...............  0                      0                      0                      0                   
                                                                                                                
                                                                                                                
Lemons...............  0                      1.2  x  10-7           0                      1.2  x  10-7        
                                                                                                                
                                                                                                                
Macadamia nuts.......  6.6  x  10-10          6.0  x  10-10          0                      1.3  x  10-9        
                                                                                                                
                                                                                                                
 Milk................  9.3  x  10-6           8.9  x  10-8           1.2  x  10-6           1.1  x  10-5        
                                                                                                                
                                                                                                                
Millet...............  0                      0                      0                      0                   
                                                                                                                
                                                                                                                
Olives...............  0                      1.2  x  10-8           0                      1.2  x  10-8        
                                                                                                                
                                                                                                                
Oranges..............  0                      5.7  x  10-6           0                      5.7  x  10-6        
                                                                                                                
                                                                                                                
Peaches..............  0                      4.5  x  10-7           0                      4.5  x  10-7        
                                                                                                                
                                                                                                                
 Pears...............  0                      3.7  x  10-7           0                      3.7  x  10-7        
                                                                                                                
                                                                                                                
Pecans...............  0                      5.8  x  10-9           0                      5.8  x  10-9        
                                                                                                                
                                                                                                                
Pineapple............  9.0  x  10-8           0                      0                      9.0  x  10-8        
                                                                                                                
                                                                                                                
 Plums...............  0                      8.9  x  10-8           0                      8.9  x  10-8        
                                                                                                                
                                                                                                                
Poultry meat.........  6.8  x  10-8           1.8  x  10-8           1.3  x  10-6           1.4  x  10-6        
                                                                                                                
                                                                                                                
 Red meat............  2.1  x  10-6           2.8  x  10-8           1.0  x  10-5           1.2  x  10-5        
                                                                                                                
                                                                                                                
Sorghum..............  4.8  x  10-7           0                      1.2  x  10-7           6.0  x  10-7        
                                                                                                                
                                                                                                                
Strawberries.........  0                      2.1  x  10-7           0                      2.1  x  10-7        
                                                                                                                
                                                                                                                
Sugarcane............  2.2  x  10-5           0                      0                      2.2  x  10-5        
                                                                                                                
                                                                                                                
Walnuts..............  0                      2.9  x  10-8           0                      2.9  x  10-8        
                                                                                                                
                                                                                                                
 Wheat...............  6.2  x  10-8           0                      2.3  x  10-6           2.4  x  10-6        
----------------------------------------------------------------------------------------------------------------
                                                                                                                
                                                                                                                
Total (Best Available  4.4  x  10-5           1.1  x  10-5           2.9  x  10-5           8.4  x  10-5        
 Data).                                                                                                         
----------------------------------------------------------------------------------------------------------------

    The excess individual lifetime cancer risks from consuming 
contaminated drinking water can also be combined for atrazine, simazine 
and cyanazine. These estimates were derived assuming that individuals 
would consume contaminated water entirely from either ground or surface 
water sources for a lifetime of 70 years. In addition, the drinking 
water risk estimates are only applicable to the population residing in 
the corn belt region of the United States, or a subset of that 
population. For example, approximately 29 million people rely on 
surface water for their drinking water in 11 major corn-producing 
states, but the actual population consuming contaminated water is 
unknown at this time. The combined cancer risks estimated from exposure 
to drinking water contaminated with atrazine, simazine and cyanazine 
are provided in Table 13:

                       Table 13.-- Triazines - Total Drinking Water Cancer Risk Estimates                       
----------------------------------------------------------------------------------------------------------------
   Exposure Pathway           Atrazine               Simazine              Cyanazine                Total       
----------------------------------------------------------------------------------------------------------------
                                                                                                                
Ground Water.........  9.9  x  10-7           8.1  x  10-8           2.3  x  10-6           3.4  x  10-6        
                                                                                                                
                                                                                                                
Surface Water........  4.2  x  10-6           6.2  x  10-7           9.7  x  10-6           1.5  x  10-5        
----------------------------------------------------------------------------------------------------------------

    Individuals are also exposed to the triazines during application to 
agricultural commodities. The occupational cancer risk estimates in 
Tables 7, 9 and 10 are based on the assumption that atrazine, simazine 
and cyanazine are applied in single active ingredient products; 
however, the triazines are routinely applied in combination either as 
pre-packaged products or as tank-mixes. The application rate tends to 
be reduced for each component triazine when applied in combination as 
compared to the rate of single active ingredient products. It is also 
possible that more than one triazine may be applied alone to a crop at 
different times during the use season. The magnitude of exposure will 
also depend upon whether the individual handling of the triazines is 
done by a private grower or commercial operator. Growers may have 
several different commodities that require triazines treatment at 
varying rates and combinations (i.e., sorghum and field corn). In the 
case of commercial operators, they are likely to treat several crops 
and use all three triazines within a given locality. Commercial 
operators will also be exposed to a greater extent because they treat 
more acres and handle more pounds of active ingredient than growers, in 
most instances.
    As with the dietary example discussed above, estimated occupational 
cancer risks from multiple triazine exposure can be added for each 
commodity separately, as well as across several commodities. The 
various combinations of exposure scenarios can be represented by a 
complex matrix. A simple example is outlined below focusing on field 
corn because it is the only site where the Agency has estimated excess 
cancer risks for workers handling all three triazines. In addition, 
field corn represents the primary use site and therefore will encompass 
a majority of workers handling the triazines. The following Table 14 
contains cancer risk estimates for private growers and commercial 
operators using ground boom equipment to apply the triazines in single 
active ingredient products and in combination with another.

                   Table 14.--Cancer Risk Estimates for Ground Boom Application to Field Corn                   
----------------------------------------------------------------------------------------------------------------
                                                             Cyanazine        Atrazine plus      Atrazine plus  
      Tasks        Atrazine Alone\1\  Simazine Alone\2\       Alone\3\         Simazine\4\        Cyanazine\5\  
----------------------------------------------------------------------------------------------------------------
                                                                                                                
M/L - grower.....  2.5  x  10-4       1.5  x  10-4       2.2  x  10-4       4.1  x  10-4       3.0  x  10-4     
                                                                                                                
                                                                                                                
A - grower.......  7.1  x  10-4       4.2  x  10-4       6.0  x  10-4       1.2  x  10-3       8.3  x  10-4     
                                                                                                                
                                                                                                                
M/L/A - grower...  9.5  x  10-4       5.8  x  10-4       8.0  x  10-4       1.6  x  10-3       1.1  x  10-3     
                                                                                                                
                                                                                                                
M/L - commercial.  7.7  x  10-3       4.6  x  10-3       6.6  x  10-3       1.3  x  10-2       1.0  x  10-2     
                                                                                                                
                                                                                                                
A - commercial...  6.5  x  10-3       3.8  x  10-3       5.4  x  10-3       1.1  x  10-2       7.6  x  10-3     
----------------------------------------------------------------------------------------------------------------
\1\ Application rate of 1.2 lb a.i./acre.                                                                       
\2\ Application rate of 1.1 lb a.i./ acre.                                                                      
\3\ Application rate of 3.0 lb a.i./ acre.                                                                      
\4\ Atrazine applied at 1.0 lb a.i./acre with 1.5 lb a.i./acre of simazine.                                     
\5\ Atrazine applied at 0.9 lb a.i./acre with 1.5 lb a.i./acre of cyanazine.                                    

    Similar considerations must be addressed for residential exposure 
scenarios. However, at this time, the Agency has estimated only the 
excess cancer risk associated with homeowner treatment of lawns with 
atrazine. Therefore, the question of residential exposure to multiple 
triazines will be evaluated in the future.

C. Combining Risks Across Multiple Pathways and Chemicals

    Excess cancer risks can be added to account for multiple exposure 
pathways for a single triazine herbicide as well as to account for 
exposure to several triazines via a single exposure pathway. The next 
step is to account for exposure from multiple pathways and from all 
triazines under consideration. In other words, this will define an 
overall estimated risk to individuals exposed to atrazine, simazine and 
cyanazine via several exposure pathways. Excess individual lifetime 
cancer risks can be estimated for each commodity or for specific 
subpopulations exposed to the triazines. This matrix of possible 
combinations is extremely complex with a simple example outlined in 
Table 15:

                  Table 15.--Total Cancer Risks Across Several Exposure Pathways and Triazines                  
----------------------------------------------------------------------------------------------------------------
   Exposure Pathway           Atrazine               Simazine              Cyanazine                TOTAL       
----------------------------------------------------------------------------------------------------------------
                                                                                                                
Dietary..............  4.4  x  10-5           1.1  x  10-5           2.9  x  10-5           8.4  x  10-5        
                                                                                                                
                                                                                                                
Drinking Water\1\....  4.2  x  10-6           6.2  x  10-7           9.7  x  10-6           1.5  x  10-5        
                                                                                                                
                                                                                                                
Occupational2,3......  1.1  x  10-3           N/A                    N/A                    1.1  x  10-3        
                                                                                                                
                                                                                                                
Residential\4\.......  2.4  x  10-5           N/A                    N/A                    2.4  x  10-5        
----------------------------------------------------------------------------------------------------------------
                                                                                                                
Total................  1.2  x  10-3           1.2  x  10-5           3.9  x  10-5           1.2  x  10-3        
----------------------------------------------------------------------------------------------------------------
\1\ Derived from surface water.                                                                                 
\2\ Private grower application to corn using ground boom equipment-mixer/loader/applicator.                     
\3\ Application of a combination of atrazine and cyanazine.                                                     
\4\ Lawn treatment by homeowner using hand cyclone spreader.                                                    

    The excess individual lifetime cancer risk for this sample 
combination is 1.2  x  10-3. This risk estimate only applies to 
those individuals living in the corn belt region, who are private 
growers and who apply an atrazine product to their lawn. Various 
combinations can be derived from this table with the number of exposed 
individuals varying as well. For example, the excess cancer risk for a 
typical resident in the corn belt region, uses atrazine on their lawn 
is 7.2  x  10-5.
    The Agency reiterates that the triazines case study presents but 
one approach in instituting the Academy's risk assessment 
recommendations. Once again, EPA invites all interested parties to 
comment on these initial attempts.

X. Triazine Ecological Risk

    Over the past 25 years, substantial scientific literature has been 
generated in the United States and abroad that analyzes the 
environmental effects from exposure to atrazine; three important 
literature reviews summarize much of this information. A review by 
Eisler (1989) (Ref. 67) contains 118 literature citations; a review by 
the Kansas Department of Health and Environment (1989) (Ref. 68) 
contains 54 citations; and a review by Huber (1993) (Ref. 69) contains 
119 citations. These reviews along with other data available to the 
Agency have been used to assess the environmental risks associated with 
atrazine use and, because of atrazine's similarities to the other two 
triazines, the risks of simazine and cyanazine.
    Significant gaps in knowledge of the impact of protracted use of 
triazines on aquatic and terrestrial ecosystem function and structure 
have limited the Agency's ability to perform a quantitative 
environmental risk assessment. However, the qualitative assessment that 
can be done raises serious concerns about the ecological risks of 
continuing to apply such massive quantities of toxic chemicals across 
ecosystems and watersheds.

A. Triazines in the Environment

    The most notable characteristic of the triazines is the vast 
quantity of these chemicals used each year in agriculture. A detailed 
discussion of the usage of the triazines is presented in Unit XI of 
this notice.
    The pervasiveness of the triazines in the environment is the result 
of their massive use combined with their mobility and persistence. Due 
to its mobility in the environment, it is estimated that between 0.1 
and 3 percent of atrazine applied to fields is lost to the aquatic 
environment (Ref. 67). At the lowest rates of loss (0.1 percent) and 
use (64 million pounds), 64,000 pounds of atrazine pollute the Nation's 
water resources every year. At the higher rates of loss and use, 
pollution jumps to 2.4 million pounds annually. Given that the three 
triazines behave similarly in their mobility, the upper limits of 
triazine pollution of water resources approaches 3.3 million pounds 
annually. For example, runoff water going into the Chesapeake Bay had 
atrazine concentrations of up to 480 g/L (Ref. 69). Other 
reports of runoff concentrations from atrazine-treated fields typically 
range from 27 to 69 g/L, but concentrations of over a 1,000 
g/L have been reported in Kansas and Colorado (Ref. 67).
    As discussed in Unit VI of this notice, the triazines have been 
found in precipitation occurring from the contamination of airborne 
particulates and dust. In one study, the annual atmospheric input of 
atrazine in rainfall to the Rhode River in Maryland was estimated at 
1,016 mg/surface ha in 1977, and 97 mg/ha in 1978 (Ref. 67). Triazines 
are also transported by fog where the maximum reading reported was 0.82 
g/L as contrasted to a maximum for rain of 2.2 g/L 
(with a mean of 0.066 g/L) (Ref. 69).
    Triazine contamination of soils occurs from intentional application 
to control unwanted weeds and unintentionally through atmospheric 
transport, runoff from treated fields, drift, irrigation and flooding 
with contaminated water, and by accident and improper disposal.

B. Environmental Exposure

    The Agency has reviewed and evaluated 12 large scale surface water 
studies; the study-specific sampling characteristics and results of 
these data have been summarized in Table 4, Unit VI of this notice. 
Included in the review and evaluation were surveys carried out by the 
Great Lakes National Program Office of the U.S. EPA, the U.S. 
Geological Survey, and the Missouri River Public Water Supplies 
Association. These studies found triazine residues are common in water, 
soil, and air/rainfall samples in high triazine use areas in the United 
States. The Agency's major ground water findings are also summarized in 
Unit VI of this notice.
    Monitoring data for aquatic resources show that residue levels and 
concentrations tend to be highest following a rainfall event shortly 
after application. Triazines are continuously present in surface water 
at concentrations that may adversely effect ecosystem structure and 
function. From July through April, triazine concentrations are 
typically below 1 g/L. However, during peak triazine usage 
during May and June, triazine concentrations increase considerably. For 
rivers in the United States, atrazine concentrations have been found at 
levels up to 245 g/L with the majority of the samples having 
concentrations below 10 g/L (See Table 4, Unit VI of this 
notice).

C. Ecological Toxicity of the Triazines

    The mode of action for triazines is to inhibit photosynthesis. This 
inhibition also affects processes that are indirectly dependent on 
photosynthesis including opening of the stomata, transpiration, ion 
transport, and other reactions that depend on the supply of energy. At 
levels between 0.1 g/L and 25 g/L, atrazine causes 
reduced photosynthesis in phytoplankton (Ref. 68). The triazines 
inhibit the flow of electrons which, in turn, inhibit the production of 
adenosine triphosphate (ATP), the major energy source for the plant. 
Without the production of ATP during photosynthesis, phytoplankton and 
other aquatic as well as semi-aquatic and terrestrial plants will be at 
risk. There is also evidence that atrazine can upset the phytohormone 
and ion balance which may seriously disrupt overall metabolism 
including RNA, enzyme and other protein synthesis (Ref. 69).
    Triazines are fatal to some aquatic plant species at very low 
concentrations. Agency guideline acute toxicity studies for aquatic 
plants resulted in EC50 values for atrazine of 22 g/L for 
Isochrysis galbana (Ref. 70); for cyanazine, 4.8 g/L for 
Navicula pelliculosa (Ref. 71); and for simazine, 36 g/L for 
Anabaena flos-aquae (Ref. 72). Field monitoring studies and reviews in 
published literature indicate that the actual toxic concentrations of 
the triazines and their degradates in the environment trigger 
deleterious effects at much lower concentrations than predicted by the 
laboratory guideline studies.
    Sensitive aquatic plant species, particularly phytoplankton, have 
been found to experience temporary, but reversible, adverse effects at 
atrazine concentrations of 1 to 5 g/L (Ref. 67).
    Specific examples of atrazine toxicity include the following: 
Wildcelery (Vallisneria americana), a submersed vascular plant, was 
clearly harmed after exposures to concentrations of 3.2 to 12 
g/L for 7 weeks (Ref. 67). At higher concentrations of 13 to 
1,104 g/L for 3 to 6 weeks, the growth of representative 
submerged macrophytes in the Chesapeake Bay was significantly 
depressed, and longer exposures were fatal (Ref. 67). Atrazine 
concentrations of 100 g/L for 14 days reportedly caused 
permanent changes in algal community structure including decreasing 
density and diversity, altered species composition and reduced growth 
(Ref. 67).
    The results of 68 experiments and studies on the effects of 
variations in atrazine exposure on a variety of aquatic plant species 
are summarized by Eisler (Ref. 67). Typically, adverse effects are 
observed for the more sensitive species at concentrations less than 10 
g/L, and at concentrations of 10 to 100 g/L for other 
species tested.
    Much of the corn belt was originally part of the Tall Grass Prairie 
ecosystem. Many species of mature native grasses are tolerant of 
atrazine, but are often susceptible as seedlings. Of eight grass 
species tested, the three most sensitive were adversely affected in 
soils containing 1.1 mg atrazine/kg. Some other species of plants such 
as mustard (Brassica juncea) were even more sensitive with germination 
reduced by 50 percent at soil concentrations between 0.02 and 0.11 mg 
atrazine/kg (Ref. 67).
    Eisler also summarizes the results of 46 studies and experiments on 
impacts of atrazine on aquatic fauna. Typically, adverse effects are 
observed with atrazine concentrations in the range of 100 g/L, 
and fatalities in the range of 1,000 g/L (Ref. 67).
    Huber concluded that ecotoxicological effects of atrazine on plant 
and animal compartments and overall ecosystem function become 
observable at 20 g/L, but these effects observed are not 
lasting. However, he did note that ecotoxicological threshold values do 
vary when individual organisms are evaluated (Ref. 69).
    1. Factors affecting organisms' susceptibility to toxic effects.The 
considerable variation in ecotoxicological results reported is due to a 
variety of factors. The rates of uptake and elimination of triazines by 
organisms is variable both within and between species. Toxicological 
effects at a given concentration within a single species can vary with 
life stage, nutritional status, natural stress factors and the presence 
of other chemicals. Within the same environment, closely related 
species can have very different exposure levels due to differences in 
behavior, food preferences or stage of development. Finally, some plant 
species such as maize and millet are very effective at detoxification 
(Ref. 69).
    2. Ecological toxicity of the triazine degradates. The toxicity, 
fate and exposure of the degradates of atrazine, simazine, and 
cyanazine are not adequately understood. Limited information indicates 
that the degradates are either nontoxic or 4 to 10 times less 
phytotoxic than their parent compound. However, given the vast 
quantities of triazines that are used each year, even a small 
percentage of the resulting moderately toxic degradates would 
contribute to the cumulative impact of triazine use on the environment.

D. Ecological Risks of the Triazines

    1. Aquatic risk assessment. There are direct adverse effects on 
aquatic plant life and secondary effects on aquatic animals that 
utilize plants for food, shelter, and breeding habitat (Refs. 67, 68, 
and 69). Eisler proposed criteria that established threshold 
concentrations above which adverse effects to aquatic life are 
expected. For example, Eisler suggested that atrazine concentrations 
below 5 g/L were adequately protective of the most sensitive 
flora and concentrations less than 11 g/L were adequately 
protective of most aquatic plants and animals. The risk to aquatic 
animals is often indirect due to a loss of food and habitat (Ref. 67). 
Maximum observed concentrations of atrazine and cyanazine exceeded the 
Agency guideline aquatic plant EC50 values (concentration at which 
50 percent of the test population is adversely affected) for atrazine, 
22 g/L for Isochrysis galbana and cyanazine, 4.8 g/L 
for Navicula pelliculosa at a substantial percentage of sites 
represented by the corn belt studies listed in Table 4, Unit VI of this 
notice. The corresponding risk quotients (expected environmental 
concentration/aquatic plant EC50) were often substantially larger 
than one, the level of concern (Ref. 73). Such data suggest that 
atrazine and cyanazine may be exerting acute effects on sensitive plant 
species at a substantial number of locations throughout the corn belt.
    Atrazine concentrations of 5 to 10 g/L are not uncommon 
during the period of peak use, late April through early July (see Table 
4, Unit VI of this notice), when biological activity in aquatic 
ecosystems is high. Peak concentrations in excess of 100 g/L 
have been reported and according to the published literature, values 
greater than 11 g/L indicate a risk to aquatic plants and 
animals (Refz. 67 and 69).
    2. Terrestrial risk assessment. The risk of triazine use to 
terrestrial organisms and ecosystems is more difficult to assess than 
the risk to aquatic systems. However, spray drift combined with the 
widespread presence of the triazines in soil, water and atmospheric 
resources through the corn belt lead to the conclusion that nontarget 
plants are periodically exposed and may suffer some adverse affects.
    3. Ecosystem impacts. Ecosystem health depends on a variety of 
factors including biomass, diversity, and energy. The long term use of 
the triazines may affect any one or all of these factors in a number of 
ways. In general, all other living organisms are dependent on plants, 
the cornerstone of ecosystems, for their very survival. Major 
reductions in plant species and total plant biomass from adverse 
impacts on photosynthesis can adversely affect the structure and 
function of the entire ecosystem. Consequently, the health of plants 
dictates, in part, the health of the ecosystem. Widespread and 
perennial use of the triazines may cause adverse impacts on 
photosynthetic production and biodiversity. These adverse impacts, in 
turn, pose a threat to aquatic and terrestrial organisms and their 
ecosystems.
    Shifts in populations may occur as a result from exposure to 
triazines due to the fact that not all species are affected in the same 
way. Such shifts in community structure could impact on animal 
populations by changes in the habitat and/or the type of food or 
availability of food. For example, one study did find that there was a 
significant reduction in nonpredatory insect populations in atrazine 
treated ponds and attributed the reduction to indirect affects, i.e., 
the loss of food and habitat (Ref. 68).
    Studies indicate that aquatic macrophytes and phytoplankton exhibit 
different levels of sensitivity to atrazine and some populations may 
develop resistance under prolonged herbicide stress. Under such 
conditions the less sensitive species would be expected to out compete 
the more sensitive resulting in a shift in community structure.
    While the acute toxicity data available for the triazines are 
important in indicating the potential for adverse effects, it is 
unknown what the entire range and extent of the effects of long term 
use of the triazines has had and will continue to have over entire 
watersheds and ecosystems. The Agency is concerned that such effects 
may be substantial.

E. Registrants' Response to Preliminary Notification Concerning 
Ecological Risks and Agency Comments

    DuPont and Ciba responded to the Agency's preliminary notification 
of possible Special Review for ecological effects. Both registrants 
believe that the triazine herbicides do not pose unreasonable risks to 
ecological systems. While the Agency is not initiating a Special Review 
of the triazines for ecological effects at this time, it does have 
concerns that such risks are possible and is interested in obtaining 
any information that will assist in refining both aquatic and 
terrestrial risk assessments. Requests for such information are 
discussed in Unit XI of this notice.

XI. Use Profile and Request for Information on Sustainable 
Agriculture/IPM, Reduced Pesticide Risk and Ecological Risks

A. Use/Usage Profile

    Atrazine, cyanazine and simazine are used principally as pre-
emergence herbicides to prevent the successful growth of a wide 
spectrum of broadleaf weeds and some grassy weeds. They are sometimes 
used as post-emergence herbicides. They have sufficient residual 
activity in the soil to provide season-long control of weed pests in 
many cases.
    The Agency estimates that 90 to 121 million pounds active 
ingredient of the triazines are used annually in the United States with 
field corn representing approximately 80 percent of the total usage and 
sorghum representing approximately 9 percent. Sweet corn and other 
sites represent the remaining 11 percent (Ref. 74). Field corn, sweet 
corn and sorghum are the only sites where more than one of the 
triazines are registered. The triazines are often used in combination 
with another herbicide to control grassy weeds.
    1. Atrazine. The major uses for which atrazine is registered 
include corn, sorghum, sugarcane, wheat fallow, macadamia nuts, guava 
and warm season turf grass. In terms of total pounds used over the past 
30 years, atrazine has been one of the two most widely used pesticides 
in the United States, the other being alachlor. However, on a per year 
basis, metolachlor has surpassed alachlor in recent years. The total 
estimated atrazine usage based on USDA, proprietary and registrant 
information up through 1993 is between 64 and 80 million pounds active 
ingredient per year; this estimate represents a decline in usage over 
the past few years.
    Field corn represents about 85 percent of total atrazine usage, 
sorghum another 11 percent, and the remainder distributed among the 
other sites. About 60 to 70 percent of U.S. field corn and sorghum 
acreage is treated with atrazine on an annual basis. Recent USDA data 
indicate that poundage may have dropped as much as 20 percent on field 
corn due to a decrease in the application rate growers actually use. In 
general, only one application a year is made to corn. Illinois, 
Indiana, Iowa and Nebraska account for 50 percent of atrazine usage, 
but 14 other states use one million pounds or more annually. Atrazine 
is principally applied by ground boom application at rates not to 
exceed 2.5 lbs. active ingredient/acre in one calendar year.
    Other crops with large percentages of total acres treated with 
atrazine are sugarcane (about 50 percent; especially Florida, 75 
percent), sweet corn (55 percent) and guava (up to 100 percent). There 
is some variation in application rate for sugarcane with users in 
Florida making more applications than users in Texas or Louisiana. On 
average, two post-emergence applications are made to sugarcane 
annually.
    To increase the scope of total weed control, atrazine is usually 
mixed with one or more additional pesticides. Common pre-emergence 
mixes for corn and sorghum are atrazine plus alachlor, atrazine plus 
metolachlor, and atrazine plus cyanazine plus alachlor or metolachlor. 
Post-emergence atrazine mixes for corn and sorghum include bentazon, 
dicamba and bromoxynil. Paraquat or glyphosate can be mixed with 
atrazine to kill existing weeds in no-till fields prior to crop 
emergence.
    2. Simazine. The major uses for which simazine is registered 
includes a variety of fruits, nuts and citrus as well as non-crop 
areas. All aquatic uses for simazine were cancelled by 1994; however, 
some existing stocks for these uses remain. Approximately 5 to 7 
million pounds active ingredient of simazine are used each year in the 
United States, primarily in California and Florida. Approximately 30 
percent of simazine's total annual usage is on corn and it is applied 
to about 2 percent of the U.S. corn crop. Simazine has fairly 
widespread usage in fruit and nut orchards because of its broad 
spectrum, long term residual weed control. Application rates for 
simazine use on food crops range from 1 to 10 lbs active ingredient/
acre and is primarily applied by ground boom, direct spray, spreaders 
or water treatment. Rates of up to 40 lbs active ingredient/acre are 
currently registered for non-crop uses.
    Simazine is persistent and has restrictions for some conditions 
where broadleaf crops may be desired for rotation. Although simazine 
was the first of the triazines to be registered for use on field corn, 
atrazine quickly replaced it because of flexibility with regard to crop 
tolerance and rotational crop restrictions.
    Simazine is commonly tank mixed with other chemicals. Such mixes 
for corn include simazine plus atrazine and probably simazine plus 
alachlor or metolachlor. Simazine may also be formulated with other 
herbicides such as atrazine, bromacil, glyphosate, paraquat dichloride, 
and sodium chlorate as a preharvest dessicant.
    Simazine usage on non-crop sites represents about 33 percent of 
total U.S. simazine usage, but this represents only a small fraction of 
the total acres for these sites. Non-crop use rates of simazine for 
total vegetation control range from 4 to 40 lbs active ingredient/acre. 
Uses of simazine on all aquatic sites were voluntarily cancelled by the 
technical registrants (Ref. 75). An existing stocks provision has been 
established for remaining stocks use on aquatic sites that pose no risk 
to human health.
    3. Cyanazine. The major uses for which cyanazine is registered 
include corn and cotton. Approximately 21 to 34 million pounds active 
ingredient are used annually, of which 95 percent is used on corn. 
Approximately 20 percent of the total U.S. corn acreage, primarily in 
Iowa, is treated with cyanazine as either the sole active ingredient or 
in combination with other herbicides. Cyanazine is used primarily where 
a broad spectrum of weed control is desirable without the carry-over 
associated with many of the more persistent herbicides. Cyanazine has a 
somewhat different weed control spectrum than atrazine and the two are 
often tank mixed. It has a relatively short persistence in soil 
compared to atrazine and simazine and has no rotational crop 
restrictions. Application is principally by ground boom (99 percent), 
but some chemigation occurs. The typical application rate for cyanazine 
is approximately 2 lbs. active ingredient/acre. The maximum label 
application rate is 6.5 lbs. active ingredient/acre.

B. Reduced Pesticide Use Initiative and Sustainable Agriculture/IPM 
Alternatives; Request for Information

    Sustainable agriculture, as defined in the Food, Agriculture, 
Conservation and Trade Act of 1990, is an ``integrated system of plant 
and animal production practices having site-specific application that 
will, over the long term, satisfy human food and fiber needs; enhance 
environmental quality and the natural resource base upon which the 
agricultural economy depends; make the most efficient use of 
nonrenewable resources and on-farm resources and integrate, where 
appropriate, natural biological cycles and controls; sustain economic 
viability of farm operations; and enhance the quality of life for 
farmers and society as a whole.'' For the triazines, pesticide 
management practices which promote use reduction, application methods 
aimed at reducing environmental loading and weed control methods using 
alternatives to chemicals can help promote the idea of sustainable 
agriculture.
    The Agency is requesting any information regarding best management 
practices that have been used to reduce pesticide use or usage, run-off 
and leaching to ground and surface water, or other environmentally 
protective measures taken while providing adequate weed control on 
sites where the triazines are registered for use. The Agency is 
requesting data which will compare the triazines to alternative 
practices that will support sustainable agriculture. Sustainable 
agricultural management practices may include crop rotation plans, use 
of buffer strips and banded application, among others. The Agency is 
requesting all relevant field test results that compare the performance 
of the triazines with that of other major pesticide alternatives. 
Additionally, the Agency is requesting data comparing the triazines at 
lower application rates and improved application methodologies to 
alternatives.
    It is well known that populations of various weed species have 
developed resistance to certain herbicides, including the triazines. 
The Agency seeks information on the prevalence and distribution of 
triazine-resistant weed species, how these resistant species are 
controlled and the role of triazines in the general problem of 
resistance management.
    The Agency is particularly interested in comparing the 
effectiveness and economic feasibility of alternative pest control 
methods. For instance, information obtained in trials about the yield 
and quality of crops grown using biological and other non-chemical weed 
control on commodities now treated with the triazines is of interest. 
Additionally, information concerning the role of triazines, other 
chemical herbicides and other weed control practices in Integrated Pest 
Management programs as well as information comparing yield, quality and 
profitability of such programs or other alternative crop production 
programs is requested.
    The Agency is also interested in receiving information to develop 
its aquatic, terrestrial and ecosystem risk assessments. This includes 
the following types of information: combined triazine and triazine 
degradate ecotoxicity, surface and ground water monitoring information 
on triazine degradates, field studies for cyanazine and simazine, 
chronic phytotoxicity studies, synergistic and cumulative effects 
between the triazines and other agricultural chemicals, possible 
interaction of triazines with abiotic factors to evaluate antagonistic 
and synergistic effects and information on exposure models and data for 
streams and lakes for each triazine and various mixtures of the three.
    In summary, the Agency is requesting all information on the 
suitability of other products and practices for maintaining the 
profitability of cropping that is obtained now by using triazines. Data 
should indicate profitability of alternative cropping systems, not 
merely relative efficacy in weed control. Especially valuable are 
comparative product performance tests in which yields and quality of 
the harvested crop are compared among various weed control chemicals 
and strategies.

XII. Duty to Submit Information on Adverse Effects

    Registrants are required by section 6(a)(2) of FIFRA to submit any 
additional information regarding unreasonable adverse effects on humans 
or the environment. In light of this Special Review and the 
requirements of FIFRA section 6(a)(2), the registrants must notify EPA 
of the results of any studies, incident reports, and any other 
information on atrazine, simazine and cyanazine pesticides currently in 
progress to the extent specified in the section 6(a)(2) enforcement 
policy (44 FR 40716). Specifically, information on any adverse 
toxicological effects of atrazine, simazine and/or cyanazine 
pesticides, their impurities, metabolites, and degradation products 
must be submitted.

XIII. Public Comment Opportunity

    All registrants and applicants for registration have been notified 
by certified mail of the Special Review being initiated on their 
triazine (atrazine, simazine and cyanazine) products. The Agency is 
providing a 120-day period to comment on this Notice. Comments must be 
submitted by March 23, 1995. The Agency invites all interested persons 
to submit further information concerning risks and benefits associated 
with the use of atrazine, simazine and cyanazine as discussed in this 
Notice. All interested persons are also invited to comment on whether 
the use of atrazine, simazine or cyanazine satisfies any of the risk 
criteria listed at 40 CFR 154.7, whether risks posed by the use of 
atrazine, simazine or cyanazine are unreasonable, and what, if any, 
regulatory action should be taken by the Agency.
    Comments claimed as CBI must be clearly marked as ``confidential,'' 
``trade secret,'' or other appropriated designation on the face of the 
comments. Comments marked as such will be treated in accordance with 
the procedures in 40 CFR 2.204(e)(4). Comments not claimed as 
confidential at the time of submission, or not clearly labeled as 
containing CBI, will be placed in the public docket. The Agency will 
consider the failure to clearly identify the claimed confidential 
status on the face of the comment as a waiver of such claim, and will 
make such information available to the public without further notice to 
the submitter.
    All comments and information should be submitted in triplicate to 
the address given in this Notice under the ADDRESSES section to 
facilitate the work of EPA and others interested in inspecting them. 
The comments and information should bear the identifying notation 
``OPP-30000-60.''
    During the comment period, interested members of the public or 
registrants may request a meeting to discuss factual information 
available to the Agency, to present any factual information, to respond 
to presentations by other persons, or to discuss what regulatory 
actions should be taken regarding the triazine herbicides. Persons 
interested in arranging such meetings should contact the person listed 
at the beginning of this Notice under ``FOR FURTHER INFORMATION 
CONTACT.''
    As part of an interagency ``streamlining'' initiative, EPA is 
experimenting with submission of public comments on selected Federal 
Register actions electronically through the Internet in addition to 
accepting comments in traditional written form. This Notice is one of 
the actions selected by EPA for this experiment. From the experiment, 
EPA will learn how electronic commenting works, and any problems that 
arise can be addressed before EPA adopts electronic commenting more 
broadly in its rulemaking activities. Electronic commenting through 
posting to the EPA Bulletin Board or through the Internet using the 
ListServe function raise some novel issues that are discussed below in 
this Unit.
    To submit electronic comments, persons can either ``subscribe'' to 
the Internet ListServe application or ``post'' comments to the EPA 
Bulletin Board. To ``Subscribe'' to the Internet ListServe application 
for this Notice, send an e-mail message to: 
[email protected] that says ``Subscribe OPP-30000-60 
 .'' Once you are subscribed to the ListServe, 
comments should be sent to: OPP[email protected].
    For online viewing of submissions and posting of comments, the 
public access EPA Bulletin Board is also available by dialing 202-488-
3671, enter selection ``DMAIL,'' user name ``BB--USER'' or 919-541-
4642, enter selection ``MAIL,'' user name ``BB--USER.'' When dialing 
the EPA Bulletin Board type  at the opening message. When the 
``Notes'' prompt appears, type ``open OPP- 30000-60'' to access the 
posted messages for this document. To get a listing of all files, type 
``dir/all'' at the prompt line. Electronic comments can also be sent 
directly to EPA at:
    [email protected].


    To obtain further information on the electronic comment process, or 
on submitting comments on this Notice electronically through the EPA 
Bulletin Board or the Internet ListServe, please contact John A. 
Richards (Telephone: 202-260-2253; FAX: 202-260-3884; Internet: 
[email protected]).
    Persons who comment on this Notice, and those who view comments 
electronically, should be aware that this experimental electronic 
commenting is administered on a completely public system. Therefore, 
any personal information included in comments and the electronic mail 
addresses of those who make comments electronically are automatically 
available to anyone else who views the comments. Similarly, since all 
electronic comments are available to all users, commenters should not 
submit electronically any information which they believe to be CBI. 
Such information should be submitted only directly to EPA in writing as 
described earlier in this Unit.
    Commenters and others outside EPA may choose to comment on the 
comments submitted by others using the OPP-30000-60 ListServe or the 
EPA Bulletin Board. If they do so, those comments as well will become 
part of EPA's record for this rulemaking. Persons outside EPA wishing 
to discuss comments with commenters or otherwise communicate with 
commenters but not have those discussions or communications sent to EPA 
and included in the EPA rulemaking record should conduct those 
discussions and communications outside the OPP-30000-60 ListServe or 
the EPA Bulletin Board.
    The official record for this rulemaking, as well as the public 
version, as described above will be kept in paper form. Accordingly, 
EPA will transfer all comments received electronically in the OPP-
30000-60 ListServe or the EPA Bulletin Board, in accordance with the 
instructions for electronic submission, into printed, paper form as 
they are received and will place the paper copies in the official 
rulemaking record which will also include all comments submitted 
directly in writing. All the electronic comments will be available to 
everyone who obtains access to the OPP-30000-60 ListServe or the EPA 
Bulletin Board; however, the official rulemaking record is the paper 
record maintained at the address in ``ADDRESSES'' at the beginning of 
this document. (Comments submitted only in written form will not be 
transferred into electronic form and thus may be accessed only by 
reviewing them in the Public Response and Program Resources Branch as 
described above.)
    Because the electronic comment process is still experimental, EPA 
cannot guarantee that all electronic comments will be accurately 
converted to printed, paper form. If EPA becomes aware, in transferring 
an electronic comment to printed, paper form, of a problem or error 
that results in an obviously garbled comment, EPA will attempt to 
contact the comment submitter and advise the submitter to resubmit the 
comment either in electronic or written form. Some commenters may 
choose to submit identical comments in both electronic and written form 
to ensure accuracy. In that case, EPA requests that commenters clearly 
note in both the electronic and written submissions that the comments 
are duplicated in the other medium. This will assist EPA in processing 
and filing the comments in the rulemaking record.
    As with ordinary written comments, at the time of receipt EPA will 
not attempt to verify the identities of electronic commenters nor to 
review the accuracy of electronic comments. Electronic and written 
comments will be placed in the rulemaking record without any editing or 
change by EPA except to the extent changes occur in the process of 
converting electronic comments to printed, paper form.
    If it chooses to respond officially to electronic comments on this 
Notice, EPA will do so either in a notice in the Federal Register or in 
a response to comments document placed in the rulemaking record for 
this Notice. EPA will not respond to commenters electronically other 
than to seek clarification of electronic comments that may be garbled 
in transmission or conversion to printed, paper form as discussed 
above. Any communications from EPA employees to electronic commenters, 
other than those described in this paragraph, either through Internet 
or otherwise are not official responses from EPA.

XIV. Public Docket

    The Agency has established a public docket [OPP-30000-60] for the 
triazine Special Review. This public docket will include: (1) The 
preliminary notification to the registrants concerning the Special 
Review of the triazines; (2) all written comments and materials [other 
than claimed confidential business information (CBI)] submitted to the 
Agency in response to the preliminary notification; (3) this notice; 
(4) any other notices pertinent to the Special Review; (5) non-CBI 
documents and copies of written comments or other materials submitted 
to the Agency in response to the pre-Special Review registrant 
notification, this notice, and any other Notice regarding the triazines 
submitted at any time during the Special Review process by any person 
outside government; (6) all documents or other written materials 
concerning the triazines Special Review provided by the Agency to any 
person or party outside of government; (7) a transcript of all public 
meetings held by the Agency for the purpose of gathering information on 
the triazines; (8) memoranda describing each meeting held during the 
Special Review process between Agency personnel and any person outside 
government; and (9) a current index of materials in the public docket. 
On a monthly basis, the Agency will distribute a compendium of indices 
for newly received comments and documents that have been placed in the 
public docket for this Special Review. This compendium will be 
distributed by mail to those members of the public who have 
specifically requested such material for this Special Review pursuant 
to 40 CFR 154.15 (f)(3).

XV. References

    The following list of references includes all documents cited in 
this notice. These documents are part of the public docket for this 
Special Review (Docket Number ``OPP-30000-60). The Agency will continue 
to supplement the public docket with additional information as it is 
received.
    The record includes the following information:
    1. U.S. Environmental Protection Agency. Preliminary 
Notification of Special Review of Atrazine. February 8, 1994.
    2. U.S. Environmental Protection Agency. Preliminary 
Notification of Special Review of Cyanazine. February 8, 1994.
    3. U.S. Environmental Protection Agency. Preliminary 
Notification of Special Review of Simazine. February 8, 1994.
    4. U.S. Environmental Protection Agency. Preliminary 
Notification of Special Review of Atrazine. August 17, 1988.
    5. U.S. Environmental Protection Agency. Preliminary 
Notification of Special Review of Atrazine. August 24, 1989.
    6. U.S. Environmental Protection Agency. Federal Register Notice 
(57 FR 29309). July 1, 1992.
    7. U.S. Environmental Protection Agency. Federal Register Notice 
(59 FR 18120). Voluntary Cancellation of the Registrations of 
Simazine for Use in Swimming Pools, Hot Tubs and Whirlpool Baths. 
April 15, 1994.
    8. U.S. Environmental Protection Agency. Federal Register Notice 
(59 FR 34614). Notice of Intent to Cancel the Registrations of Nuclo 
Dry Granular Algaecide, Nuclo Dry Algaecide 90, Winterizing 
Algaecide, and Algicil Plus. July 6, 1994.
    9. Mayhew, D.A.; Taylor, G.D.; Smith, S.H. and Banas, D.A. 
Twenty-four Month Combined Chronic Oral Toxicity and Oncogenicity 
Study in Rats Utilizing Atrazine Technical. Conducted by American 
Biogenics Corporation for Ciba-Geigy Corp. Study No. 410-1102. 
Accession No. 262714-262727. April 29, 1986.
    10. Hazelette, J.R., and Green, J.D. Atrazine - Technical: 91-
Week Oral Carcinogenicity Study in Mice. MRID No. 40431302. Study 
No. 842120. Testing Facility: Division of Toxicology/Pathology, 
Ciba-Geigy Corp. October 30, 1987.
    11. U.S, Environmental Protection Agency. Memorandum from Judith 
W. Hauswirth, Office of Pesticide Programs, Health Effects Division: 
``Peer Review of Atrazine.'' June 6, 1988.
    12. U.S. Environmental Protection Agency. Memorandum from Judith 
W. Hauswirth, Office of Pesticide Programs, Health Effects Division: 
``Second Peer Review of Atrazine.'' August 1, 1988.
    13. U.S, Environmental Protection Agency. Memorandum from Marion 
P. Copley, Office of Pesticide Programs, Health Effects Division: 
``Third Peer Review of Atrazine - Reevaluation Following the 
September 7, 1988 Scientific Advisory Panel Review.'' November 22, 
1988.
    14. U.S, Environmental Protection Agency. Memorandum from Marion 
P. Copley, Office of Pesticide Programs, Health Effects Division: 
``Follow-up to the Third Peer Review of Atrazine.'' April 27, 1989.
    15. U.S. Environmental Protection Agency. Memorandum from C. J. 
Nelson, Office of Pesticide Programs, Health Effects Division. 
``Atrazine - Updated Qualitative and Quantitative Risk Assessment 
from a Rat 2-Year Chronic Oral Toxicity/Oncogenicity Study.'' August 
23, 1988.
    16. U.S, Environmental Protection Agency. Memorandum from Marion 
P. Copley, Office of Pesticide Programs, Health Effects Division: 
``ID 0808030: Atrazine; Reevaluation of Chronic Toxicity in the 1-
year Dog Study.'' December 19, 1989.
    17. McCormick, C.C. and A.T.Arthur: ``Simazine-Technical: 104-
Week Oral Chronic Toxicity and Carcinogenicity Study in Rats.'' 
April 12, 1988. MRID Number: 406144-05. Study Number: 2-001109. 
Testing Facility: Pharmaceuticals Division, Ciba-Geigy Corp.
    18. Hazelette, J.R., and Green, J.D. Simazine Technical; 95-Week 
Oral Toxicity/Oncogenicity Study in Mice. MRID No. 40614404. Study 
No. 842121. Testing Facility: Pharmaceuticals Division, Ciba-Geigy 
Corp. April 4, 1988.
    19. Lasinski, E.; Kapaghian, J. and Green, J. Gene Mutation 
Test: Simazine Technical. MRID No. 40614406. Study No. 87038; 
872269. Unpublished study prepared by Ciba-Geigy Corp. 1987.
    20. U.S, Environmental Protection Agency. Memorandum from Esther 
Rinde, Office of Pesticide Programs, Health Effects Division: ``Peer 
Review of Simazine.'' July 31, 1989.
    21. U.S. Environmental Protection Agency. Memorandum from 
Bernice Fisher, Office of Pesticide Programs, Health Effects 
Division. ``Simazine - Quantitative Risk Assessment, Two Year 
Chronic/Oncogenicity Sprague-Dawley Rat Study.'' June 5, 1989.
    22. U.S. Environmental Protection Agency. Memorandum from Henry 
Spencer, Office of Pesticide Programs, Health Effects Division. 
``Peer Review of Simazine Following SAP Review.'' May 24, 1990.
    23. Bogdanffy, M.S.: Combined chronic toxicity/oncogenicity 
study with cyanazine in rats. Unpublished report prepared by Haskell 
Laboratory and submitted by E.I. DuPont de Nemours and company. 
Study No. 23-90. MRID No. 415099-02. May 11, 1990.
    24. U.S. Environmental Protection Agency. Memorandum from 
William Dykstra and George Z. Ghali, Office of Pesticide Programs, 
Health Effects Division. ``Peer Review of Cyanazine (Bladex).'' May 
21, 1991.
    25. Jannasch, M., V. Sawin. ``Genetic Toxicity Assay of Bladex 
Herbicide: Gene Mutation Assay in Mammalian Cells in Culture, 
L5178Y, Mouse Lymphoma Cells: Project No. 61282.'' Unpublished study 
prepared by Westhollow Research Center. 1986.
    26. ``Determination of Unscheduled DNA Synthesis in Rat 
Spermatocytes following in vivo Exposure to Cyanazine by Oral 
Gavage.'' Haskell Laboratory. Study No. 281-93. April 18, 1993.
    27. U.S. Environmental Protection Agency. Memorandum from Reto 
Engler, Office of Pesticide Programs, Health Effects Division. 
``Cyanazine; Quantitative Estimate of Carcinogenic Risk: Oral Slope 
Factor.'' June 14, 1993.
    28. U.S. Environmental Protection Agency. Memorandum from Jerome 
Blondell, Office of Pesticide Programs, Health Effects Division. 
``Italian Triazine Cancer Epidemiology Studies, HED Project No. 0-
1573.'' September 21, 1990.
    29. Munger, R., P. Isacson, M. Kramer, J. Hanson, T. Burns, K. 
Cherryholmes, And W. Hausler, Jr. ``Birth Defects and Pesticide 
Contaminated Water Supplies in Iowa.'' Presented at Society for 
Epidemiologic Research, Minneapolis, MN. June 1992.
    30. U.S. Environmental Protection Agency. Memorandum from Jerome 
Blondell, Office of Pesticide Programs, Health Effects Division. 
``Review of Midwest Cancer Epidemiology Studies Related to 
Triazines. HED Project No. INTRA-0141.'' February 14, 1991.
    31. Thornton, J. ``Breast Cancer and the Environment: The 
Chlorine Connection.'' Greenpeace. 1992
    32. Davis, D. L., et. al. ``Medical Hypothesis: Xenoestrogens As 
Preventable Causes of Breast Cancer.'' Environmental Health 
Perspectives. Vol. 101, No. 5, October 1993.
    33. U.S. Environmental Protection Agency. Letter from Penelope 
A. Fenner-Crisp, Office of Pesticide Programs, Health Effects 
Division to Thomas J. Parshley, Ciba-Geigy Corporation. May 8, 1994.
    34. U.S. Environmental Protection Agency. Memorandum from Ralph 
Cooper, Office of Research and Development, Developmental Toxicology 
Division. ``Review of Atrazine Hormonal Data.'' May 31, 1994.
    35. U.S. Environmental Protection Agency. Memorandum from Thomas 
M. Crisp, Office of Research and Development, Reproductive and 
Developmental Toxicology Branch. ``Review and Evaluation of Ciba-
Geigy's Atrazine/Hormone Studies (MRID 427439-02 and -03), along 
with their Overview 429425-00 Document.'' March 1, 1994.
    36. U.S. Environmental Protection Agency. Memorandum from John 
Abbotts, Office of Pesticide Programs, Health Effects Division. 
``Determination of Anticipated Residues.'' September 22, 1992.
    37. U.S. Environmental Protection Agency. Memorandum from 
Richard Griffin, Office of Pesticide Programs, Health Effects 
Division. ``Revised Dietary Exposure Analysis for Atrazine Special 
Review.'' May 21, 1990.
    38. U.S. Environmental Protection Agency. Memorandum from 
Richard Griffin, Office of Pesticide Programs, Health Effects 
Division. ``Carcinogenic Risk for Simazine Registered Commodities.'' 
February 19, 1991.
    39. U.S. Environmental Protection Agency. Memorandum from 
Stephen A. Schaible, Office of Pesticide Programs, Health Effects 
Division. ``Carcinogenic Risk Assessment for Cyanazine Using a 
Q1* of 1.0 (mg/kg/day)-1.'' October 25, 1994.
    40. U.S. Environmental Protection Agency. Federal Register 
Notice (59 FR 42261). August 17, 1994.
    41. U.S. Environmental Protection Agency. Federal Register 
Notice (56 FR 3526). January 30, 1991.
    42. U.S. Environmental Protection Agency. Memorandum from George 
Z. Ghali, Office of Pesticide Programs, Health Effects Division. 
``Report of OPP RfD/Peer Review on Atrazine.'' April 27, 1993.
    43. Ciba-Geigy Corporation. ``Petition to the Environmental 
Protection Agency for Reconsideration of and Request for Stay of the 
MCLG and MCL for Atrazine, 56 FR 3526 (January 30, 1991).'' November 
16, 1993.
    44. U.S. Environmental Protection Agency. Letter from Carol M. 
Browner, Administrator. ``Petition for Reconsideration and 
Administrative Stay of Drinking Water Regulations.'' October 17, 
1994.
    45. U.S. Environmental Protection Agency. Federal Register 
Notice (57 FR 31776). July 17, 1992.
    46. DuPont Agricultural Products. Letter from Tony E. Catka to 
Margaret Stasikowski, Office of Water, Health and Ecological 
Criteria Division. ``Scientific Basis for Evaluating the Cyanazine 
HAL.'' August 30, 1993.
    47. U.S. Environmental Protection Agency. Draft Water Resources 
Impact Analysis for the Triazine Herbicides. Office of Pesticide 
Programs, Environmental Fate and Effects Division. February 1992.
    48. DuPont Agricultural Products. Letter from Tony Catka to 
Robert Taylor: section 6(a)(2) data submitted October 18, 1991.
    49. Ciba-Geigy Corporation. Letter from Karen Stumpf to Robert 
Taylor: section 6(a)(2) data submitted June 8, 1994. MRID No. 
43267401.
    50. Blasland and Bouck Engineers. ``Final Report: Investigation 
of Atrazine in Hoover Reservoir.'' November 1991.
    51. Kloibel, S. ``1990 Rathbun Reservoir Water Quality 
Monitoring.'' MRID No. 43065801. 1993.
    52. Goolsby, D.A., L.L. Boyer and G.E. Mallard. ``Selected 
Papers on Agricultural Chemicals in Water Resources of the 
Midcontinental United States.'' U.S. Geological Survey - Report No. 
93-418. 1993.
    53. Tierney, D. ``A Review of Surface Water Monitoring for 
Atrazine in the Chesapeake Bay Watershed (1976-1991).'' MRID No. 
42547109. Submitted by Ciba-Geigy Corporation November 3, 1992.
    54. Goolsby, D.A. and E.M. Thurman. ``Herbicides in Rivers and 
Streams of the Upper Midwestern United States.'' Proceedings of the 
46th Annual Meeting of the Upper Mississippi River Conservation 
Committee. 1991.
    55. Holden, P. and C. Eiden. ``State Ground Water Monitoring 
Study for Atrazine and Its Major Degradation Products in the United 
States.'' First and Second Reports. Unpublished studies submitted by 
Ciba-Geigy Corporation. Lab Project No. 174-91. MRID Nos. 43016507 
and 43215001. 1993 and 1994.
    56. Meyer, M.T. and Thurman, E.M. ``Transport of Cyanazine and 
Atrazine Metabolites in the Unsaturated Zone.'' Presented at the 
American Chemical Society Meeting, Division of Environmental 
Chemistry, Washington, D.C., August 21-25, 1994.
    57. Goolsby, D.A., E.M. Thurman and M.L. Pomes. ``Herbicides in 
Atmospheric Wet Deposition in the Upper Midwest and Northeast United 
States.'' Presented at 201st American Chemical Society National 
Meeting, Atlanta, GA. April 14-19, 1991.
    58. Goolsby, D.A. and E.M. Thurman. ``Deposition of Herbicides 
in Rainfall in the Midwest and Northeast United States, 19901991.'' 
Presented at 1993 American Geophysical Union Spring Meeting, 
Baltimore, MD. May 24-28, 1993.
    59. Hatfield, J.L., J.H. Prueger, R.L. Pfeiffer and T.R. 
Steinheimer. ``Precipitation Quality in the Rural Areas of Iowa.'' 
Presented at Soil and Water Conservation Society Symposium, 
Minneapolis, MN. February 21-24, 1993.
    60. U.S. Environmental Protection Agency. Memorandum from Mike 
Beringer, Office of Pesticide Programs, Health Effects Division. 
``Drinking Water Risk Estimates for Triazines PD 1.'' October 6, 
1994.
    61. Ershow, A.G. and K.P. Cantor. ``Total Water and Tap Water 
Intake in the United States: Population-Based Estimates of 
Quantities and Sources.'' May 1989.
    62. U.S. Environmental Protection Agency. Memorandum from 
Stephen Schaible, Office of Pesticide Programs, Health Effects 
Division. ``Carcinogenic Risk Assessment for Triazine Herbicides in 
Drinking Water, Assuming Less Than MCL Residues.'' August 17, 1993.
    63. U.S. Environmental Protection Agency. Letter from Margaret 
Stasikowski to Leslie A. Warner, DuPont Agricultural and Regulatory 
Affairs. April 14, 1994.
    64. U.S. Environmental Protection Agency. Memorandum from 
Michael Beringer, Office of Pesticide Programs, Health Effects 
Division. ``Revised Occupational and Residential Risk Assessment for 
the Triazines.'' March 7, 1994.
    65. U.S. Environmental Protection Agency. Memorandum from 
Michael Beringer, Office of Pesticide Programs, Health Effects 
Division. ``Revised MOE and Cancer Risk Estimates for Atrazine Use 
on Turf.'' August 11, 1994.
    66. U.S. Environmental Protection Agency. Memorandum from Henry 
Spencer, Office of Pesticide Programs, Health Effects Division. 
``Atrazine Kinetic Data Use In Exposure and Risk Assessments.'' 
March 25, 1993.
    67. Eisler, R. ``Atrazine Hazards to Fish, Wildlife, and 
Invertebrates: A Synoptic Review.'' U.S. Fish and Wildlife Service 
Biological Report 85. 1989.
    68. Kansas Department of Health and Environment. ``Atrazine in 
Kansas.'' March 1989.
    69. Huber, W. ``Toxicological Relevance of Atrazine in Aquatic 
Ecosystems.'' Environmental Toxicology and Chemistry. Vol.12. 1993.
    70. Parrish, R. ``Effects of Atrazine on Two Freshwater and Five 
Marine Algae.'' Laboratory No. H82-500. Conducted by EG and G 
Bionomics, Maine Research Laboratory, Pensacola, FL. Submitted by 
Ciba Geigy Corp., Greensboro, NC. MRID No. 41065204. 1978.
    71. Hughes, J.S. and T.L. Williams. ``Cyanazine: Toxicity to 
Navicula pelliculosa.'' Laboratory Study ID No. B382-165-3. 
Conducted by Malcolm Pirnie, Inc., Tarrytown, NY. Submitted by E. I. 
DuPont deNemours and Co., Inc. Wilmington, DE. 1993.
    72. Thompson, S.G. and J.P. Swigert. ``Simazine: A 5-Day 
Toxicity Test with the Freshwater Alga (Anabaena flos-aquae).'' Lab. 
Project No. 108A-129. Conducted by Wildlife International Ltd., 
Easton, MD. Submitted by Ciba Geigy Corp., Greensboro, NC. 1992.
    73. U.S. Environmental Protection Agency. Memorandum from Henry 
Nelson and Sharlene Matten. ``Surface Water Analysis and Aquatic 
Plant Risk Quotients - Comparison of Maximum Concentrations to Plant 
EC50s. October 14, 1994.
    74. U.S. Environmental Protection Agency. Note from Bob Torla, 
Office of Pesticide Programs, Biological and Economic Analysis 
Division. ``Update of Triazine Usage Estimates.'' August 11, 1994.
    75. U.S. Environmental Protection Agency. Federal Register 
Notice (59 FR 6020). February 9, 1994.

List of Subjects

    Enviromental protection, chemicals, pesticides and pest.

    Dated: November 9, 1994.

Lynn R. Goldman,
Assistant Administrator for Prevention, Pesticides and Toxic 
Substances.

[FR Doc. 94-28553 Filed 11-22-94; 8:45 am]
BILLING CODE 6560-50-F