[Federal Register Volume 65, Number 127 (Friday, June 30, 2000)]
[Notices]
[Pages 40632-40639]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-16633]


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ENVIRONMENTAL PROTECTION AGENCY

[PF-951; FRL-6592-6]


Notice of Filing Pesticide Petitions to Establish a Tolerance for 
Certain Pesticide Chemicals in or on Food

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: This notice announces the initial filings and amendments of 
pesticide petitions proposing the establishment/amendments of 
regulations for residues of certain pesticide chemicals in or on 
various food commodities.

[[Page 40633]]


DATES: Comments, identified by docket control number PF-951, must be 
received on or before July 31, 2000.

ADDRESSES: Comments may be submitted by mail, electronically, or in 
person. Please follow the detailed instructions for each method as 
provided in Unit I.C. of the `` SUPPLEMENTARY INFORMATION.'' To ensure 
proper receipt by EPA, it is imperative that you identify docket 
control number PF-951 in the subject line on the first page of your 
response.

FOR FURTHER INFORMATION CONTACT: By mail: Vera Soltero, Registration 
Division (7505C), Office of Pesticide Programs, Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460; 
telephone number: (703) 308-9359; and e-mail address: 
[email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    You may be affected by this action if you are an agricultural 
producer, food manufacturer or pesticide manufacturer. Potentially 
affected categories and entities may include, but are not limited to:

 
------------------------------------------------------------------------
                                                          Examples of
           Categories                    NAICS            potentially
                                                       affected entities
------------------------------------------------------------------------
Industry                          111                 Crop production
                                  112                 Animal production
                                  311                 Food manufacturing
                                  32532               Pesticide
                                                       manufacturing
------------------------------------------------------------------------

    This listing is not intended to be exhaustive, but rather provides 
a guide for readers regarding entities likely to be affected by this 
action. Other types of entities not listed in the table could also be 
affected. The North American Industrial Classification System (NAICS) 
codes have been provided to assist you and others in determining 
whether or not this action might apply to certain entities. If you have 
questions regarding the applicability of this action to a particular 
entity, consult the person listed under ``FOR FURTHER INFORMATION 
CONTACT.''

B. How Can I Get Additional Information, Including Copies of this 
Document and Other Related Documents?

    1. Electronically. You may obtain electronic copies of this 
document, and certain other related documents that might be available 
electronically, from the EPA Internet Home Page at http://www.epa.gov/. 
To access this document, on the Home Page select ``Laws and 
Regulations'' and then look up the entry for this document under the 
``Federal Register--Environmental Documents.'' You can also go directly 
to the Federal Register listings at http://www.epa.gov/fedrgstr/.
    2. In person. The Agency has established an official record for 
this action under docket control number PF-951. The official record 
consists of the documents specifically referenced in this action, any 
public comments received during an applicable comment period, and other 
information related to this action, including any information claimed 
as confidential business information (CBI). This official record 
includes the documents that are physically located in the docket, as 
well as the documents that are referenced in those documents. The 
public version of the official record does not include any information 
claimed as CBI. The public version of the official record, which 
includes printed, paper versions of any electronic comments submitted 
during an applicable comment period, is available for inspection in the 
Public Information and Records Integrity Branch (PIRIB), Rm. 119, 
Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA, from 8:30 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The 
PIRIB telephone number is (703) 305-5805.

C. How and to Whom Do I Submit Comments?

    You may submit comments through the mail, in person, or 
electronically. To ensure proper receipt by EPA, it is imperative that 
you identify docket control number PF-951 in the subject line on the 
first page of your response.
    1. By mail. Submit your comments to: Public Information and Records 
Integrity Branch (PIRIB), Information Resources and Services Division 
(7502C), Office of Pesticide Programs (OPP), Environmental Protection 
Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
    2. In person or by courier. Deliver your comments to: Public 
Information and Records Integrity Branch (PIRIB), Information Resources 
and Services Division (7502C), Office of Pesticide Programs (OPP), 
Environmental Protection Agency, Rm. 119, Crystal Mall #2, 1921 
Jefferson Davis Highway, Arlington, VA. The PIRIB is open from 8:30 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The 
PIRIB telephone number is (703) 305-5805.
    3. Electronically. You may submit your comments electronically by 
e-mail to: ``[email protected] ,'' or you can submit a computer disk 
as described above. Do not submit any information electronically that 
you consider to be CBI. Avoid the use of special characters and any 
form of encryption. Electronic submissions will be accepted in 
Wordperfect 6.1/8.0 or ASCII file format. All comments in electronic 
form must be identified by docket control number PF-951. Electronic 
comments may also be filed online at many Federal Depository Libraries.

D. How Should I Handle CBI That I Want to Submit to the Agency?

    Do not submit any information electronically that you consider to 
be CBI. You may claim information that you submit to EPA in response to 
this document as CBI by marking any part or all of that information as 
CBI. Information so marked will not be disclosed except in accordance 
with procedures set forth in 40 CFR part 2. In addition to one complete 
version of the comment that includes any information claimed as CBI, a 
copy of the comment that does not contain the information claimed as 
CBI must be submitted for inclusion in the public version of the 
official record. Information not marked confidential will be included 
in the public version of the official record without prior notice. If 
you have any questions about CBI or the procedures for claiming CBI, 
please consult the person identified under ``FOR FURTHER INFORMATION 
CONTACT.''

E. What Should I Consider as I Prepare My Comments for EPA?

    You may find the following suggestions helpful for preparing your 
comments:
    1. Explain your views as clearly as possible.
    2. Describe any assumptions that you used.
    3. Provide copies of any technical information and/or data you used 
that support your views.
    4. If you estimate potential burden or costs, explain how you 
arrived at the estimate that you provide.
    5. Provide specific examples to illustrate your concerns.
    6. Make sure to submit your comments by the deadline in this 
notice.
    7. To ensure proper receipt by EPA, be sure to identify the docket 
control number assigned to this action in the subject line on the first 
page of your response. You may also provide the name, date, and Federal 
Register citation.

[[Page 40634]]

II. What Action is the Agency Taking?

    EPA has received pesticide petitions as follows proposing the 
establishment and/or amendment of regulations for residues of certain 
pesticide chemicals in or on various food commodities under section 408 
of the Federal Food, Drug, and Comestic Act (FFDCA), 21 U.S.C. 346a. 
EPA has determined that these petitions contain data or information 
regarding the elements set forth in section 408(d)(2); however, EPA has 
not fully evaluated the sufficiency of the submitted data at this time 
or whether the data supports granting of the petition. Additional data 
may be needed before EPA rules on the petition.

List of Subjects

    Environmental protection, Agricultural commodities, Feed additives, 
Food additives, Pesticides and pests, Reporting and recordkeeping 
requirements.

    Dated: June 23, 2000.
James Jones,
Director, Registration Division, Office of Pesticide Programs.

Summaries of Petitions

    Petitioner summaries of the pesticide petitions are printed below 
as required by section 408(d)(3) of the FFDCA. The summaries of the 
petitions were prepared by the petitioners and represent the views of 
the petitioners. EPA is publishing the petition summaries verbatim 
without editing them in any way. The petition summary announces the 
availability of a description of the analytical methods available to 
EPA for the detection and measurement of the pesticide chemical 
residues or an explanation of why no such method is needed.

Initial Filings

1. Aventis CropScience USA LP

PP 0E6162

    EPA has received a pesticide petition 0E6162 from Aventis 
CropScience, P.O. Box 12014, 2 T.W. Alexander Drive, Research Triangle 
Park, NC 27709, proposing, pursuant to section 408(d) of the Federal 
Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 
CFR part 180 by establishing a tolerance for residues of ethyl 5,5-
diphenyl-2-isoxazoline-3-carboxylate (CAS No. 163520-33-0) (herbicide 
safener isoxadifen-ethyl, Company Code AE F122006) in or on the raw 
agricultural commodities corn grain at 0.1 parts per million (ppm), 
corn forage at 0.3 ppm, and corn stover at 0.5 ppm. EPA has determined 
that the petition contains data or information regarding the elements 
set forth in section 408(d)(2) of the FFDCA; however, EPA has not fully 
evaluated the sufficiency of the submitted data at this time or whether 
the data support granting of the petition. Additional data may be 
needed before EPA rules on the petition.

A. Residue Chemistry

    1. Plant metabolism. The metabolism of isoxadifen-ethyl (ethyl 5,5-
diphenyl-2-isoxazoline-3-carboxylate) in corn and rice has been 
investigated and is understood. Total residue levels in corn 
commodities were very low. The initial metabolic transformation of 
isoxadifen-ethyl in plants is hydrolysis of the prominent ester 
function, yielding the carboxylic acid, AE F129431 (4,5-dihydro-5,5-
diphenyl-3-isoxazolecarboxylic acid), the principal metabolite in 
forage, grain and stover. The pathway then proceeds via hydroxylation 
of the phenyl ring to AE F162241 (4,5-dihydro-5-(4-hydroxyphenyl)-5-
phenyl-3-isoxazolecarboxylic acid) which was also significant in forage 
and stover. AE F129431 and AE F162241 were also identified in a rice 
metabolism and rat metabolism study.
    2. Analytical method. Based on the results of the metabolism 
studies, the analytical targets selected were the parent compound, 
isoxadifen-ethyl, the major metabolite AE F129431 and the minor 
metabolite AE F162241. A practical method for the determination of 
these targets is available. Extractable residues of isoxadifen-ethyl 
and its two metabolites are extracted from crops with blending in a 
mixture of acidic aqueous acetonitrile. After washing with hexane and 
treatment with saturated brine, the analytes of interest are 
partitioned into dichoromethane. Isoxadifen-ethyl is separated from the 
two acidic metabolites by selective solid phase extraction, 
concentrated and quantified by capillary gas chromatography with ion-
trap mass spectrometric detection. The extract containing the 
metabolites is divided in two portions. One portion is treated with 
trimethylsilyl-diazomethane to convert AE F129431 to its methylated 
derivative then quantified by capillary gas chromatography with ion-
trap mass spectrometric detection. AE F162241 is quantified in the 
second portion by high performance liquid chromatography with ion-trap 
mass spectrometric detection. The limits of quantification (LOQ) are 
0.02 ppm in corn grain and 0.05 ppm in corn forage and stover.
    3. Magnitude of residues. Residue trials were carried out in a 
total of 29 field residue trials, in the U.S. and Canada using a water 
dispersible granule (WG) formulation containing 50% weight/weight (w/w) 
isoxadifen-ethyl. The preparation was predominantly applied in a split 
application of 30 grams/hectares (g/ha) followed by 60 g/ha. In a 
limited number of Canadian trials the treatments were split as two 
sequential applications of 45 grams active ingredient/hectare (g ai/ha) 
each. In the U.S. trials a single application of 160 g ai/ha was also 
investigated. Pre-harvest intervals were between 37 to 67, 60 to 121 
and 79 to 151 days for forage, grain and stover, respectively. No 
residues of the parent compound were detected in any corn grain stover 
or forage. Isoxadifen-ethyl derived residues in corn grain were limited 
to isolated observations of the metabolite AE F129431, to a maximum of 
0.06 ppm. Residues in corn stover and forage were only observed in the 
form of AE F129431 and AE F162241. Following treatment of the corn with 
two applications totaling 90 g ai/ha, residues of AE F129431 and AE 
F162241 reached respective maxima of 0.13 ppm and 0.08 ppm in stover 
but were not detected in forage. Following treatment of the corn with a 
single application of 160 g ai/ha, residues of AE F129431 reached 
respective maxima of 0.35 ppm and 0.15 ppm in stover and forage. 
Following the higher application rate, residues of AE F162241 reached 
respective maxima of 0.1 ppm and 0.05 ppm in stover and forage. 
Tolerances are being proposed for the parent compound and AE F129431. 
Tolerances for the combined residues of isoxadifen-ethyl and AE F129431 
are proposed at 0. 1 ppm, 0.3 ppm and 0.5 ppm respectively, for grain, 
forage and stover. Tolerances are not proposed for the more polar 
metabolite, AE F162241 as it is not found in corn grain. In animal feed 
items levels are considerably lower than AE F129431 and it does not 
accumulate in animal tissues.
    In a corn processing study, no residues above 0.02 milligrams/
kilograms (mg/kg) were observed in corn grain following treatment of 
the crop at the nominal rate of 150 followed by 300 g ai/ha. This 
exaggerated rate is approximately five times the maximum proposed label 
rate. Since no residues were observed in the raw agricultural 
commodity, neither analysis of the processed commodities nor tolerances 
are required. Although corn grain is fed to cattle and poultry and 
cattle may be grazed on forage or fed stover, tolerances in meat, milk 
or eggs are not necessary for a safener because metabolism studies in 
cattle and poultry indicated very low residue levels at

[[Page 40635]]

dosing rates considerably higher than anticipated from field ingestion.

B. Toxicological Profile

    1. Acute toxicity. Isoxadifen-ethyl is slightly toxic following 
acute oral exposure, no more than slightly toxic following acute dermal 
exposure and practically non-toxic following acute inhalation exposure. 
The acute rat oral LD50 of isoxadifen-ethyl was 1,740 mg/kg. 
The acute rat dermal LD50 was greater than 2,000 mg/kg and 
the 4-hour rat inhalation LC50 was > 5 milligrams/liter (mg/
L). Isoxadifen-ethyl was slightly irritating to rabbit eyes and non-
irritating to rabbit skin. Based on these results, isoxadifen-ethyl 
would be classified as EPA Category III for oral and dermal toxicity 
and eye irritation, and EPA Category IV for inhalation toxicity and 
dermal irritation. Technical isoxadifen-ethyl was shown to be a dermal 
sensitizer in a guinea pig maximization assay, but no evidence of 
sensitization has been observed in a Buehler assay when formulated into 
a commercial product.
    2. Genotoxicity. No evidence of genotoxicity was noted in 
Salmonella and E. coli reverse bacterial mutation assays, an in vitro 
mammalian gene mutation assay in Chinese hamster lung (V79) cells, an 
in vivo unscheduled DNA synthesis assay in rat hepatocytes, or a mouse 
micronucleus assay. An increase in chromosomal aberrations was observed 
in an in vitro assay in Chinese hamster lung (V79) cells, but only at 
toxic concentrations. Thus, the overall weight of evidence indicates 
that isoxadifen-ethyl does not possess significant genotoxic activity.
    3. Reproductive and developmental toxicity. A rat developmental 
toxicity study was conducted at dose levels of 0, 15, 120, and 1,000 
mg/kg/day. Maternal toxicity (including one death) was noted at 1,000 
mg/kg/day. Slight developmental toxicity (an increase in resorptions) 
but no evidence of teratogenicity was also noted at this level. No 
effects were noted at 120 mg/kg/day, which was considered to be the no 
observed adverse effect level (NOAEL) for both maternal and 
developmental toxicity.
    A rabbit developmental toxicity study was conducted at dose levels 
of 0, 5, 50, and 500 mg/kg/day. Maternal effects at 500 mg/kg/day 
consisted of decreased food consumption, slight weight loss during 
gestation days 6-8, and one death. In addition, one animal at 500 mg/
kg/day had only two empty implantation sites. No evidence of 
teratogenicity or developmental toxicity was noted. Thus, 50 mg/kg/day 
was considered to be the NOAEL for maternal toxicity while 500 mg/kg/
day was the NOAEL for developmental effects.
    In the 2-generation reproduction study in the rat, administration 
of isoxadifen-ethyl at 4,000 ppm, resulted in parental toxicity in both 
sexes from the F0 and F1 generation consisting of 
reduction in body weight gain food intake and an increase in 
microscopic kidney lesions. The only effect seen in the offspring was 
lower pup weights of the F1 generation together with a delay 
in achievement of vaginal patency and balanopreputial separation (due 
to the reduced body weight), at 4,000 ppm. The weights of F0 
males were significantly reduced throughout the pre-mating treatment 
period; those of F2 females were reduced only during the 
first week after weaning. The NOAEL for both parental and neonatal 
toxicity was 200 ppm, equivalent to an overall mean achieved intake of 
about 16.4 mg/kg body weight/day.
    4. Subchronic toxicity. In a 90-day rat feeding study, isoxadifen-
ethyl was administered at dietary concentrations of 0, 20, 200, 2,000, 
and 4,000 ppm. The NOAEL for this study was considered to be 200 ppm 
(approximately 15.3 mg/kg/day) based on decreased weight gain at 2,000 
ppm, and decreased weight gain, increased liver weights, and 
centrilobular hepatocyte enlargement at 4,000 ppm.
    In a 90-day feeding study in mice, isoxadifen-ethyl was 
administered at dietary concentrations of 13, 125, 1,250, and 2,500 
ppm. Decreased kidney weights, increased liver weights, and 
histopathological changes in the liver (centrilobular hepatocyte 
enlargement and vacuolation) were noted at 1,250 and 2,500 ppm. The 
NOAEL for this study was 125 ppm (approximately 23 mg/kg/day).
    In a 90-day dog feeding study, isoxadifen-ethyl was administered to 
beagle dogs at dietary concentrations of 0, 25, 125, and 1,000 ppm. 
Dietary administration of 1,000 ppm isoxadifen-ethyl exceeded the 
maximum tolerated dose (MTD), and it was concluded that 700 ppm would 
be a suitable high dose level for a chronic dog study. The NOAEL for 
this 90-day study was considered to be 25 ppm (approximately 1.3 mg/kg/
day) based on slight histopathological effects in the kidneys at 125 
ppm, and effects on the kidneys, spleen, liver, heart, and intestines 
at 1,000 ppm.
    5. Chronic toxicity. Chronic toxicity has been assessed in both the 
rat and the dog. In the rat combined chronic toxicity and oncogenicity 
study, the liver was the target organ as evidenced by increases in 
liver weight and centrilobular hepatocyte hypertrophy. The no-effect 
level was 200 ppm (10 mg/kg/day). Whilst in the dog the kidney was the 
target organ with vacuolation of the straight tubular cytoplasm 
occurring at the high dose level. The no-effect level was 3.5 mg/kg/day 
indicating, as in the subchronic studies, that the dog is the most 
sensitive species. Based on the dog, Aventis CropScience believes the 
Reference Dose (RfD) for isoxadifen-ethyl is 0.035 mg/kg/day. No 
carcinogenic activity was detected in dogs, mice, and rats at the 
Maximum Tolerated Dose (MTD). Isoxadifen-ethyl is not oncogenic in 
dogs, rats, or mice and is not likely to be carcinogenic in humans. 
Aventis CropScience believes isoxadifen-ethyl should be classified as a 
``Not Likely'' carcinogen based on the lack of carcinogenicity in rats 
and mice.
    6. Animal metabolism. The metabolism of isoxadifen-ethyl has been 
determined in the rat and dog. In both species the main metabolic route 
was hydrolysis of the ester to yield the free acid AE F129431 (5,5-
diphenyl-2-isoxazoline-3-carboxylic acid), which is the same as 
observed in plants. This was the only significant metabolic route in 
the dog following either gavage or dietary dosing. In the rat there was 
an additional metabolic route which led to the formation of a 
hydroxylated free acid, AE F162241 (4,5-dihydro-5-(4-hydroxyphenyl)-5-
phenyl-3-isoxazolecarboxylic acid), also a plant metabolite. This was a 
major metabolic route in male rats, particular at the low-dose, but was 
only a minor metabolic route in female rats. Unchanged isoxadifen-ethyl 
was only excreted in trace amounts in the feces. There were a number of 
minor ( 3%) polar metabolites also excreted, which were not identified. 
A further plant metabolite AE C637375 (b-hydroxy-b-
benzenepropanenitrile) was also shown to be a trace metabolite in the 
rat.
    The metabolism of isoxadifen-ethyl in ruminants is adequately 
understood. A dairy cow was dosed with the compound at a level 
equivalent to 11.52 ppm in the diet for 7 days. Total residue levels 
were very low. Parent compound was seen in fats and milk only. The 
carboxylic acid, AE F129431, was the major metabolite identified in all 
of the tissues, with traces also being found in the milk.
    The metabolism of isoxadifen-ethyl in poultry is also adequately 
understood. Laying hens were fed the compound at a level equivalent to 
11 ppm in the diet for 14 days. Residue levels were low in all 
commodities. The vast majority of the dose was excreted as AE F129431, 
with smaller amounts of AE F162241

[[Page 40636]]

and isoxadifen-ethyl. AE F129431 was the major metabolite identified in 
all of the tissues and yolks. Trace amounts of isoxadifen-ethyl and AE 
F162241 were detected in liver and eggs with isoxadifen-ethyl also 
being detected in the muscle. The metabolic profile of isoxadifen-ethyl 
in the hen was similar to that seen in the cow and rat.
    7. Endocrine disruption. No special studies have been conducted to 
investigate the potential of isoxadifen-ethyl to induce estrogenic or 
other endocrine effects. However, no evidence of estrogenic or other 
endocrine effects have been noted in any of the standard toxicology 
studies that have been conducted with this product and there is no 
reason to suspect that any such effects would be likely.

C. Aggregate Exposure

    1. Dietary exposure. Isoxadifen-ethyl will be used only as a 
herbicide safener for use on rice and corn. No non-agricultural uses 
are anticipated. Thus, the only potential sources of non-occupational 
exposure to isoxadifen-ethyl would consist of any potential residues in 
food and drinking water. As previously indicated, in the absence of any 
acute toxicity concerns, only chronic exposures have been evaluated.
    i. Food. Chronic dietary analysis was conducted to estimate 
exposure to potential isoxadifen-ethyl derived residues in/on corn. A 
Tier One analysis was conducted using the Dietary Expected Evaluation 
Model (DEEM) software and the 1994-1996 CSFII food consumption data. It 
was assumed that residues were at proposed tolerance levels in rice 
(0.05 ppm) and corn grain (0.1 ppm) and that 100% of crop was treated. 
Additionally, based on the results from appropriate studies, it was 
assumed that there was no concentration into processed commodities and 
that contributions from residues in meat, milk or eggs are not 
required. A chronic RfD of 0.035 mg/kg/day is derived from the NOAEL of 
3.5 mg/kg/day in the most sensitive species, dog. Using these inputs 
the chronic dietary exposure estimate from residues of isoxadifen-ethyl 
for the U.S. population was 0.000173 mg/kg /day or 0.5% of its RfD. For 
the sub-population with the highest exposure, non-nursing infants, the 
chronic dietary exposure estimate from residues of isoxadifen-ethyl was 
0.000448 mg/kg/day, or 1.3% of its RfD. These values are highly 
conservative, having been based on worst case assumptions of tolerance 
level residues and 100% of the crop treated.
    ii. Drinking water. EPA's Standard Operating Procedure (SOP) for 
Drinking Water Exposure and Risk Assessments was used to perform the 
drinking water assessment. This SOP uses a variety of tools to conduct 
drinking water assessment. These tools include water models such as 
Screening Concentration in Ground Water (SCI-GROW), Generic Expected 
Environmental Concentration (GENEEC), Pesticide Root Zone Model 
(PRZMS)/EXAMS, and monitoring data. If monitoring data are not 
available then the models are used to predict potential residues in 
surface and ground water and the highest is assumed to be the drinking 
water residue. In the case of isoxadifen-ethyl monitoring data do not 
exist; therefore, model calculations were used to estimate a water 
residue. The calculated drinking water levels of comparison (DWLOC) for 
chronic exposures for all adults and children greatly exceed the 
drinking water estimated concentrations (DWEC) from the models. The 
chronic DWLOC for adults is 1,218 parts per billion (ppb). The chronic 
DWLOC for children/toddlers is 346 ppb. The worst case chronic DWEC is 
0.165 ppb based on a PRZM/EXAMS simulation of runoff into surface water 
in a standard EPA exposure assessment scenario for corn (MLRA 111, 
Ohio). The DWEC represents combined residues of isoxadifen-ethyl and AE 
F129431, expressed as isoxadifen-ethyl equivalents.
    2. Non-dietary exposure. Exposure to isoxadifen-ethyl for the 
mixer/loader/ground boom/aerial applicator was calculated using the 
Pesticide Handlers Exposure Database (PHED). It was assumed that the 
product would be applied to a maximum of 50 ha per day (125 acres/day) 
by ground boom applicator and 140 ha per day (350 acres/day) by aerial 
applicator at a maximum use rate of 45 g a.i./ha. Normal work attire 
consisting of long-sleeved shirt, long pants, and protective gloves was 
assumed in the PHED assessment. Margins of exposure (MOEs) for a 70 kg 
operator were calculated utilizing a dermal NOAEL of 1,000 mg/kg body 
weight/day from the rat dermal toxicity study and an inhalation NOAEL 
of 3.5 mg/kg body weight/day based on the dog chronic toxicity study. 
The combined MOE (inhalation plus dermal) for isoxadifen-ethyl was 
28,000 for a ground operator undertaking mixing, loading and spraying. 
For aerial application where the mixer/loader was assumed to be a 
different operator from the pilot combined MOEs were 17,000 for the 
mixer/loader and 233,000 for the pilot. The results indicate that large 
margins of safety exist for the proposed use of isoxadifen-ethyl.

D. Cumulative Effects

    There is no information to indicate that isoxadifen-ethyl may share 
a common mechanism of toxicity with any other chemical. Thus, this 
assessment was not needed.

E. Safety Determination

    1. U.S. population. Using the conservative assumptions described 
above, based on the completeness and reliability of the toxicity data, 
it is concluded that aggregate exposure, in this case food only, to the 
proposed uses of AE F 122006 will utilize at most 0.5% of the reference 
dose for the U.S. population. The actual exposure is likely to be much 
less as more realistic data and models are developed. EPA generally has 
no concern for exposures below 100% of the RfD because the RfD 
represents the level at or below which daily aggregate exposure over a 
lifetime will not pose appreciable risk to human health. Drinking water 
levels of comparison based on the dietary exposure are much greater 
than highly conservative estimated levels, and would be expected to be 
well below the 100% level of the RfD, if they occur at all. Therefore, 
there is a reasonable certainty that no harm will occur to the U.S. 
population from aggregate exposure (food and drinking water) to 
isoxadifen-ethyl.
    2. Infants and children. No evidence of increased sensitivity to 
fetuses was noted in There has been no indication of reproductive 
effects or indication of increased sensitivity to the offspring in the 
2-generation rat reproduction study. No additional safety factor to 
protect infants and children is necessary as there is no evidence of 
increased sensitivity in infants and children.
    Using the conservative assumptions described in the exposure 
section above, the percent of the RfD that will be used for exposure to 
residues of isoxadifen-ethyl in food for non-nursing infants (the most 
highly exposed subgroup) is 1.3%. The children (1-6) exposure is 1.1% 
of the RfD. As in the adult situation, DWLOCs are much higher than the 
worst case DWECs and are expected to use well below 100% of the RfD, if 
they occur at all. Therefore, there is a reasonable certainty that no 
harm will occur to infants and children from aggregate exposure to 
residues of AE F122006.

F. International Tolerances

    There are no Codex Alimentarius Commission maximum residue levels

[[Page 40637]]

established for residues of isoxadifen-ethyl.

2. Cabot Corporation

PP 0E6109

    EPA has received a pesticide petition (0E6109) from Cabot 
Corporation, 75 State St., Boston, MA, 02109 proposing, pursuant to 
section 408(d) of the FFDCA, 21 U.S.C. 346a(d), to amend 40 CFR part 
180 to establish an exemption from the requirement of a tolerance for 
silicon dioxide, fumed, amorphous when used in accordance with good 
agricultural practices as an inert ingredient in pesticide formulations 
applied to animals. Silicon dioxide, fumed, amorphous is already 
exempted from the requirements of a tolerance when used as an inert 
ingredient in pesticide formulations applied to growing crops or to raw 
agricultural commodities after harvest. EPA has determined that the 
petition contains data or information regarding the elements set forth 
in section 408(d)(2) of the FFDCA; however, EPA has not fully evaluated 
the sufficiency of the submitted data at this time or whether the data 
support granting of the petition. Additional data may be needed before 
EPA rules on the petition.

A. Residue Chemistry

    No residue chemistry data are presented in the petition as the 
Agency does not generally require these data to rule on the exemption 
from the requirement of a tolerance for an inert ingredient.

B. Toxicological Profile

    The Agency has established a set of criteria which identifies 
categories of polymers that present low risk. These criteria (described 
in 40 CFR 723.250) identify polymers that are relatively unreactive and 
stable compounds compared to other chemical substances as well as 
polymers that typically are not readily absorbed. These properties 
generally limit polymer's ability to cause adverse effects. The Agency 
believes that polymers meeting the criteria noted above will present 
minimal or no risk. Cabot Corporation believes that silicon dioxide, 
fumed, amorphous conforms to the definition of a polymer given in 40 
CFR 723.250(b) and meet the following criteria used to identify a low 
risk polymer.
    1. Silicon dioxide, fumed, amorphous is not a cationic polymer, nor 
is it reasonably anticipated to become a cationic polymer in a natural 
aquatic environment.
    2. Silicon dioxide, fumed, amorphous contains as an integral part 
of its composition the atomic elements silicon and oxygen.
    3. Silicon dioxide, fumed, amorphous does not contain as an 
integral part of its composition, except as impurities, any element 
other than those listed in 40 CFR 723.250(d)(2)(iii).
    4. Silicon dioxide, fumed, amorphous is not designed, nor is it 
reasonably anticipated to substantially degrade, decompose or 
depolymerize prior to, during, or after use.
    5. Silicon dioxide, fumed, amorphous is not manufactured or 
imported from monomers and/or reactants that are not included on the 
Toxic Substances and Control Act (TSCA) substance inventory or 
manufactured under an applicable TSCA section 5 exemption.
    6. Silicon dioxide, fumed, amorphous is not a water absorbing 
polymer with a number average molecular weight greater than or equal to 
10,000.
    7. Silicon dioxide, fumed, amorphous has a minimum-average 
molecular weight of 645,000 daltons. Substances with molecular weights 
greater than 400 generally are not absorbed through the intact skin, 
and substances with molecular weights greater than 1,000 generally are 
not absorbed through the gastrointestinal (GI) tract. Chemicals not 
absorbed though the skin or GI tract generally are incapable of 
eliciting a toxic response.
    8. Silicon dioxide, fumed, amorphous has a minimum average 
molecular weight of 645,000 daltons. Silicon dioxide meets the 
requirements for molecular weight distribution of oligomer contents of 
less than 5% with molecular weights less than 1,000 and less than 2% 
with molecular weights less than 500.
    Cabot Corporation believes that sufficient information has been 
submitted to assess the hazards of silicon dioxide, fumed, amorphous. 
No toxicology data are being submitted as the Agency does not generally 
require these data to rule on the exemption from the requirement of a 
tolerance for an inert ingredient. Because silicon dioxide conforms 
with the definition of a polymer and meets the criteria of a polymer 
under 40 CFR 723.250, Cabot Corporation believes there are no concerns 
for risks associated with toxicity.

C. Aggregate Exposure

    1. Dietary exposure. Silicon dioxide, fumed, amorphous is not 
absorbed through the intact gastrointestinal tract and is incapable of 
eliciting a toxic response.
    2. Drinking water. Silicon dioxide, fumed, amorphous is not soluble 
in water and therefore there is no reason to expect human exposure to 
residues in water.
    3. Non-dietary exposure. For most uses of silicon dioxide, fumed, 
amorphous the primary route of exposure is dermal. Silicon dioxide, 
fumed, amorphous with a molecular weight significantly greater than 400 
is not absorbed through the intact skin.

D. Cumulative Effects

    Cabot Corporation believes that sufficient information has been 
submitted to assess the hazards of silicon dioxide, fumed, amorphous. 
Because silicon dioxide, fumed, amorphous conforms with the definition 
of a polymer and meets the criteria of a polymer under 40 CFR 723.250, 
Cabot Corporation believes there are no concerns for risks associated 
with cumulative effects.

E. Safety Determination

    1. U.S. population. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of silicon 
dioxide, fumed, amorphous. Because silicon dioxide, fumed, amorphous 
conforms with the definition of a polymer and meets the criteria of a 
polymer under 40 CFR 723.250, Cabot Corporation believes there are no 
concerns for risks associated with any potential exposure to adults.
    2. Infants and children. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of silicon 
dioxide, fumed, amorphous. Because silicon dioxide, fumed, amorphous 
conforms with the definition of a polymer and meets the criteria of a 
polymer under 40 CFR 723.250, Cabot Corporation believes there are no 
concerns for risks associated with exposure to infants and children.

Amended Petitions

1. Cabot Corporation

9E6017

    EPA has received an amendment to a pesticide petition (9E6017) from 
Cabot Corporation, 75 State St., Boston, MA, 02109 proposing, pursuant 
to section 408(d) of the FFDCA, 21 U.S.C. 346a(d), to amend 40 CFR part 
180 to amend an exemption from the requirement of a tolerance for 
dimethyl silicone polymer with silica (TS-720) when used in accordance 
with good agricultural practices as an inert ingredient in pesticide 
formulations applied to growing crops in or on the raw agricultural 
commodity after harvest or to animals. The initial notice of filing was 
published in the Federal Register of August 25, 1999 (64 FR 46378) 
(FRL-

[[Page 40638]]

6096-1). EPA has determined that the petition contains data or 
information regarding the elements set forth in section 408(d)(2) of 
the FFDCA; however, EPA has not fully evaluated the sufficiency of the 
submitted data at this time or whether the data support granting of the 
petition. Additional data may be needed before EPA rules on the 
petition.
    An exemption from the requirement of a tolerance under 40 CFR 
180.1001(c) and (e) was established for dimethyl silicone polymer with 
silica in the Federal Register on March 1, 2000 (65 FR 10946) (FRL-
6490-9), with the following uses: ``moisture barrier, anti-caking 
agent, anti-settling agent.'' This amendment to the petition requests 
that the use ``thickening agent'' be added so that the uses for 
dimethyl silicone polymer with silica under 40 CFR 180.1001(c) and (e) 
will read as follows: ``moisture barrier, anti-caking agent, anti-
settling agent, thickening agent.''

A. Residue Chemistry

    No residue chemistry data are presented in the petition as the 
Agency does not generally require these data to rule on the exemption 
from the requirement of a tolerance for an inert ingredient.

B. Toxicological Profile

    As discussed in the March 1, 2000 Federal Register, dimethyl 
silicone polymer with silica meets all the criteria for a low risk 
polymer, as specified in 40 CFR 723.250.

C. Aggregate Exposure

    1. Dietary exposure. Dimethyl silicone polymer with silica is not 
absorbed through the intact gastrointestinal tract and is incapable of 
eliciting a toxic response.
    2. Drinking water. Dimethyl silicone polymer with silica is not 
soluble in water and therefore there is no reason to expect human 
exposure to residues in water.
    3. Non-dietary exposure. For most uses of dimethyl silicone polymer 
with silica, the primary route of exposure is dermal. Dimethyl silicone 
polymer with silica with a molecular weight significantly greater than 
400 is not absorbed through the intact skin.

D. Cumulative Effects

    Cabot Corporation believes that sufficient information has been 
submitted to assess the hazards of dimethyl silicone polymer with 
silica. Because dimethyl silicone polymer with silica conforms with the 
definition of a polymer and meets the criteria of a polymer under 40 
CFR 723.250, Cabot Corporation believes there are no concerns for risks 
associated with cumulative effects.

E. Safety Determination

    1. U.S. population. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of TS-720. Because 
TS-720 conforms with the definition of a polymer and meets the criteria 
of a polymer under 40 CFR 723.250, Cabot Corporation believes there are 
no concerns for risks associated with any potential exposure to adults.
    2. Infants and children. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of dimethyl 
silicone polymer with silica. Because dimethyl silicone polymer with 
silica conforms with the definition of a polymer and meets the criteria 
of a polymer under 40 CFR 723.250, Cabot Corporation believes there are 
no concerns for risks associated with exposure to infants and children.

2. Cabot Corporation

9E6018

    EPA has received an amendment to a pesticide petition (9E6018) from 
Cabot Corporation, proposing, pursuant to section 408(d) of the FFDCA, 
21 U.S.C. 346a(d), to amend 40 CFR part 180 to amend an exemption from 
the requirement of a tolerance for silane, dichloromethyl-, reaction 
product with silica (TS-610) when used in accordance with good 
agricultural practices as an inert ingredient in pesticide formulations 
applied to growing crops in or on the raw agricultural commodity after 
harvest or to animals. The initial notice of filing was published in 
the Federal Register of August 25, 1999 (64 FR 46378) (FRL-6096-1). EPA 
has determined that the petition contains data or information regarding 
the elements set forth in section 408(d)(2) of the FFDCA; however, EPA 
has not fully evaluated the sufficiency of the submitted data at this 
time or whether the data support granting of the petition. Additional 
data may be needed before EPA rules on the petition.
    An exemption from the requirement of a tolerance under 40 CFR 
180.1001(c) and (e) was established for silane, dichloromethyl-, 
reaction product with silica in the Federal Register of March 1, 2000 
(65 FR 10946) (FRL-6490-9), with the following uses: ``moisture 
barrier, anti-caking agent, anti-settling agent, anti-thickening 
agent.'' This petition amendment requests that ``anti-thickening'' be 
revised by deleting ``anti,'' so that the uses for silane, 
dichloromethyl-, reaction product with silica under 40 CFR 180.1001(c) 
and (e) will read as follows: ``moisture barrier, anti-caking agent, 
anti-settling agent, thickening agent.''

A. Residue Chemistry

    No residue chemistry data are presented in the petition as the 
Agency does not generally require these data to rule on the exemption 
from the requirement of a tolerance for an inert ingredient.

B. Toxicological Profile

    As discussed in the March 1, 2000 Federal Register, silane, 
dichloromethyl-, reaction product with silica meets all the criteria 
for a low risk polymer, as specified in 40 CFR 723.250.

C. Aggregate Exposure

    1. Dietary exposure. Silane, dichloromethyl-, reaction product with 
silica is not absorbed through the intact gastrointestinal tract and is 
incapable of eliciting a toxic response.
    2. Drinking water. Silane, dichloromethyl-, reaction product with 
silica is not soluble in water and therefore there is no reason to 
expect human exposure to residues in water.
    3. Non-dietary exposure. For most uses of silane, dichloromethyl-, 
reaction product with silica the primary route of exposure is dermal. 
Silane, dichloromethyl-, reaction product with silica, with a molecular 
weight significantly greater than 400, is not absorbed through the 
intact skin.

D. Cumulative Effects

    Cabot Corporation believes that sufficient information has been 
submitted to assess the hazards of silane, dichloromethyl-, reaction 
product with silica. Because silane, dichloromethyl-, reaction product 
with silica conforms with the definition of a polymer and meets the 
criteria of a polymer under 40 CFR 723.250, Cabot Corporation believes 
there are no concerns for risks associated with cumulative effects.

E. Safety Determination

    1. U.S. population. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of silane, 
dichloromethyl-, reaction product with silica. Because silane, 
dichloromethyl-, reaction product with silica conforms with the 
definition of a polymer and meets the criteria of a polymer under 40 
CFR 723.250, Cabot Corporation believes there are no concerns for risks 
associated with any potential exposure to adults.

[[Page 40639]]

    2. Infants and children. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of TS-610. Because 
silane, dichloromethyl-, reaction product with silica conforms with the 
definition of a polymer and meets the criteria of a polymer under 40 
CFR 723.250, Cabot Corporation believes there are no concerns for risks 
associated with exposure to infants and children.

3. Cabot Corporation

9E6019

    EPA has received an amendment to a pesticide petition (9E6019) from 
Cabot Corporation proposing, pursuant to section 408(d) of the FFDCA, 
21 U.S.C. 346a(d), to amend 40 CFR part 180 to amend an exemption from 
the requirement of a tolerance for hexamethyldisilizane, reaction 
product with silica (TS-530) when used in accordance with good 
agricultural practices as an inert ingredient in pesticide formulations 
applied to growing crops in or on the raw agricultural commodity after 
harvest or to animals. The initial notice of filing was published in 
the Federal Register of August 25, 1999 (64 FR 46378) (FRL-6096-1). EPA 
has determined that the petition contains data or information regarding 
the elements set forth in section 408(d)(2) of the FFDCA; however, EPA 
has not fully evaluated the sufficiency of the submitted data at this 
time or whether the data support granting of the petition. Additional 
data may be needed before EPA rules on the petition.
    An exemption from the requirement of a tolerance under 40 CFR 
180.1001(c) and (e) was established for hexamethyldisilizane, reaction 
product with silica in the Federal Register of March 1, 2000 (65 FR 
10946) (FRL-6490-9), with the following uses: ``moisture barrier, anti-
caking agent, anti-settling agent.'' This petition amendment requests 
that the use ``thickening agent'' be added so that the uses for TS-530 
under 40 CFR 180.1001(c) and (e) will read as follows: ``moisture 
barrier, anti-caking agent, anti-settling agent, thickening agent.''

A. Residue Chemistry

    No residue chemistry data are presented in the petition as the 
Agency does not generally require these data to rule on the exemption 
from the requirement of a tolerance for an inert ingredient.

B. Toxicological Profile

    As discussed in the March 1, 2000 Federal Register, 
hexamethyldisilizane, reaction product with silica meets all the 
criteria for a low risk polymer, as specified in 40 CFR 723.250.

C. Aggregate Exposure

    1. Dietary exposure. Hexamethyldisilizane, reaction product with 
silica is not absorbed through the intact gastrointestinal tract and is 
incapable of eliciting a toxic response.
    2. Drinking water. Hexamethyldisilizane, reaction product with 
silica is not soluble in water and therefore there is no reason to 
expect human exposure to residues in water.
    3. Non-dietary exposure. For most uses of hexamethyldisilizane, 
reaction product with silica the primary route of exposure is dermal. 
Hexamethyldisilizane, reaction product with silica with a molecular 
weight significantly greater than 400 is not absorbed through the 
intact skin.

D. Cumulative Effects

    Cabot Corporation believes that sufficient information has been 
submitted to assess the hazards of hexamethyldisilizane, reaction 
product with silica. Because hexamethyldisilizane, reaction product 
with silica conforms with the definition of a polymer and meets the 
criteria of a polymer under 40 CFR 723.250, Cabot Corporation believes 
there are no concerns for risks associated with cumulative effects.

E. Safety Determination

    1. U.S. population. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of 
hexamethyldisilizane, reaction product with silica. Because 
hexamethyldisilizane, reaction product with silica conforms with the 
definition of a polymer and meets the criteria of a polymer under 40 
CFR 723.250, Cabot Corporation believes there are no concerns for risks 
associated with any potential exposure to adults.
    2. Infants and children. Cabot Corporation believes that sufficient 
information has been submitted to assess the hazards of 
hexamethyldisilizane, reaction product with silica. Because 
hexamethyldisilizane, reaction product with silica conforms with the 
definition of a polymer and meets the criteria of a polymer under 40 
CFR 723.250, Cabot Corporation believes there are no concerns for risks 
associated with exposure to infants and children.
[FR Doc. 00-16633 Filed 6-29-00; 8:45 am]
BILLING CODE 6560-50-F