[Federal Register Volume 63, Number 67 (Wednesday, April 8, 1998)]
[Rules and Regulations]
[Pages 17101-17108]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-9392]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 180, 185, and 186

[OPP-300642; FRL-5784-9]
RIN 2070-AB78


Clethodim; Time-Limited Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes time-limited tolerances for 
combined residues of clethodim and its metabolites containing the 5-(2-
ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-
hydroxycyclohexene-3-one moieties and their sulphoxides and sulphones, 
all expressed as clethodim in or on alfalfa, forage; alfalfa, hay; dry 
beans; peanuts; peanut, hay; peanut, meal; tomatoes; tomato, puree; 
tomato, paste. Valent U.S.A. Corporation requested this tolerance under 
the Federal Food, Drug and Cosmetic Act (FFDCA), as amended by the Food 
Quality Protection Act of 1996 (Pub. L. 104-170). The tolerances will 
expire on April 30, 2001.

DATES: This regulation is effective April 8, 1998. Objections and 
requests for hearings must be received byEPA on or before June 8, 1998.

ADDRESSES: Written objections and hearing requests, identified by the 
docket control number, [OPP-300620], must be submitted to: Hearing 
Clerk (1900), Environmental Protection Agency, Rm. M3708, 401 M St., 
SW., Washington, DC 20460. Fees accompanying objections and hearing 
requests shall be labeled ``Tolerance Petition Fees'' and forwarded to: 
EPA Headquarters Accounting Operations Branch, OPP (Tolerance Fees), 
P.O. Box 360277M, Pittsburgh, PA 15251. A copy of any objections and 
hearing requests filed with the Hearing Clerk identified by the docket 
control number, [OPP-300620], must also be submitted to: Public 
Information and Records Integrity Branch, Information Resources and 
Services Division (7502C), Office of Pesticide Programs, Environmental 
Protection Agency, 401 M St., SW., Washington, DC 20460. In person, 
bring a copy of objections and hearing requests to Rm. 119, CM #2, 1921 
Jefferson Davis Hwy., Arlington, VA.
    A copy of objections and hearing requests filed with the Hearing 
Clerk may also be submitted electronically by sending electronic mail 
(e-mail) to: [email protected]. Copies of objections and 
hearing requests must be submitted as an ASCII file avoiding the use of 
special characters and any form of encryption. Copies of objections and 
hearing requests will also be accepted on disks in WordPerfect 5.1/6.1 
file format or ASCII file format. All copies of objections and hearing 
requests in electronic form must be identified by the docket control 
number [OPP-300620]. No Confidential Business Information (CBI) should 
be submitted through e-mail. Electronic copies of objections and 
hearing requests on this rule may be filed online at many Federal 
Depository Libraries.

FOR FURTHER INFORMATION CONTACT: By mail: Joanne I. Miller, 
Registration Division 7505C, Office of Pesticide Programs, 
Environmental Protection Agency, 401 M St., SW., Washington, DC 20460. 
Office location, telephone number, and e-mail address: Crystal Mall #2, 
1921 Jefferson Davis Hwy., Arlington, VA, 703-305-6224, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: In the Federal Register of February 12, 1997 
(62 FR 6530-6534) (FRL-5586-3), EPA, issued a notice pursuant to 
section 408 of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 
U.S.C. 346a(e) announcing the filing of a pesticide petition (PP) for 
tolerance by Valent U.S.A. Corporation, 1333 N. California Blvd., 
Walnut Creek, CA 94596. This notice included a summary of the petition 
prepared by Valent, the registrant. There were no comments

[[Page 17102]]

received in response to the notice of filing.
    The petition requested that 40 CFR 180.458 be amended by 
establishing time-limited tolerances for combined residues of the 
herbicide clethodim and its metabolites containing the 5-(2-
ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-
hydroxycyclohexene-3-one moieties and their sulphoxides and sulphones, 
all expressed as clethodim, in or on alfalfa, forage at 6 part per 
million (ppm); alfalfa, hay at 10 ppm; dry beans at 2 ppm; peanuts at 3 
ppm; peanut, hay at 3 ppm; peanut, meal at 5 ppm; tomatoes at 1 ppm; 
tomato, puree at 2 ppm; and tomato, paste at 3 ppm. This tolerance will 
expire on April 30, 2001.

I. Risk Assessment and Statutory Findings

    New section 408(b)(2)(A)(i) of the FFDCA allows EPA to establish a 
tolerance (the legal limit for a pesticide chemical residue in or on a 
food) only if EPA determines that the tolerance is ``safe.'' Section 
408(b)(2)(A)(ii) defines ``safe'' to mean that ``there is a reasonable 
certainty that no harm will result from aggregate exposure to the 
pesticide chemical residue, including all anticipated dietary exposures 
and all other exposures for which there is reliable information.'' This 
includes exposure through drinking water and in residential settings, 
but does not include occupational exposure. Section 408(b)(2)(C) 
requires EPA to give special consideration to exposure of infants and 
children to the pesticide chemical residue in establishing a tolerance 
and to ``ensure that there is a reasonable certainty that no harm will 
result to infants and children from aggregate exposure to the pesticide 
chemical residue. . . .''
    EPA performs a number of analyses to determine the risks from 
aggregate exposure to pesticide residues. First, EPA determines the 
toxicity of pesticides based primarily on toxicological studies using 
laboratory animals. These studies address many adverse health effects, 
including (but not limited to) reproductive effects, developmental 
toxicity, toxicity to the nervous system, and carcinogenicity. Second, 
EPA examines exposure to the pesticide through the diet (e.g., food and 
drinking water) and through exposures that occur as a result of 
pesticide use in residential settings.

A. Toxicity

    1. Threshold and non-threshold effects. For many animal studies, a 
dose response relationship can be determined, which provides a dose 
that causes adverse effects (threshold effects) and doses causing no 
observed effects (the ``no-observed effect level'' or ``NOEL'').
    Once a study has been evaluated and the observed effects have been 
determined to be threshold effects, EPA generally divides the NOEL from 
the study with the lowest NOEL by an uncertainty factor (usually 100 or 
more) to determine the Reference Dose (RfD). The RfD is a level at or 
below which daily aggregate exposure over a lifetime will not pose 
appreciable risks to human health. An uncertainty factor (sometimes 
called a ``safety factor'') of 100 is commonly used since it is assumed 
that people may be up to 10 times more sensitive to pesticides than the 
test animals, and that one person or subgroup of the population (such 
as infants and children) could be up to 10 times more sensitive to a 
pesticide than another. In addition, EPA assesses the potential risks 
to infants and children based on the weight of the evidence of the 
toxicology studies and determines whether an additional uncertainty 
factor is warranted. Thus, an aggregate daily exposure to a pesticide 
residue at or below the RfD (expressed as 100% or less of the RfD) is 
generally considered acceptable by EPA. EPA generally uses the RfD to 
evaluate the chronic risks posed by pesticide exposure. For shorter 
term risks, EPA calculates a margin of exposure (MOE) by dividing the 
estimated human exposure into the NOEL from the appropriate animal 
study. Commonly, EPA finds MOEs lower than 100 to be unacceptable. This 
100-fold MOE is based on the same rationale as the 100-fold uncertainty 
factor.
    Lifetime feeding studies in two species of laboratory animals are 
conducted to screen pesticides for cancer effects. When evidence of 
increased cancer is noted in these studies, the Agency conducts a 
weight of the evidence review of all relevant toxicological data 
including short-term and mutagenicity studies and structure activity 
relationship. Once a pesticide has been classified as a potential human 
carcinogen, different types of risk assessments (e.g., linear low dose 
extrapolations or MOE calculation based on the appropriate NOEL) will 
be carried out based on the nature of the carcinogenic response and the 
Agency's knowledge of its mode of action.
    2. Differences in toxic effect due to exposure duration. The 
toxicological effects of a pesticide can vary with different exposure 
durations. EPA considers the entire toxicity data base, and based on 
the effects seen for different durations and routes of exposure, 
determines which risk assessments should be done to assure that the 
public is adequately protected from any pesticide exposure scenario. 
Both short and long durations of exposure are always considered. 
Typically, risk assessments include ``acute,'' ``short-term,'' 
``intermediate term,'' and ``chronic'' risks. These assessments are 
defined by the Agency as follows.
    Acute risk, by the Agency's definition, results from 1-day 
consumption of food and water, and reflects toxicity which could be 
expressed following a single oral exposure to the pesticide residues. 
High end exposure to food and water residues are typically assumed.
    Short-term risk results from exposure to the pesticide for a period 
of 1-7 days, and therefore overlaps with the acute risk assessment. 
Historically, this risk assessment was intended to address primarily 
dermal and inhalation exposure which could result, for example, from 
residential pesticide applications. However, since enaction of FQPA, 
this assessment has been expanded to include both dietary and non-
dietary sources of exposure, and will typically consider exposure from 
food, water, and residential uses when reliable data are available. In 
this assessment, risks from average food and water exposure, and high-
end residential exposure, are aggregated. High-end exposures from all 
three sources are not typically added because of the very low 
probability of this occurring in most cases, and because the other 
conservative assumptions built into the assessment assure adequate 
protection of public health. However, for cases in which high-end 
exposure can reasonably be expected from multiple sources (e.g. 
frequent and widespread homeowner use in a specific geographical area), 
multiple high-end risks will be aggregated and presented as part of the 
comprehensive risk assessment/characterization. Since the toxicological 
endpoint considered in this assessment reflects exposure over a period 
of at least 7 days, an additional degree of conservatism is built into 
the assessment; i.e., the risk assessment nominally covers 1-7 days 
exposure, and the toxicological endpoint/NOEL is selected to be 
adequate for at least 7 days of exposure. (Toxicity results at lower 
levels when the dosing duration is increased.)
    Intermediate-term risk results from exposure for 7 days to several 
months. This assessment is handled in a manner similar to the short-
term risk assessment.
    Chronic risk assessment describes risk which could result from 
several months

[[Page 17103]]

to a lifetime of exposure. For this assessment, risks are aggregated 
considering average exposure from all sources for representative 
population subgroups including infants and children.

B. Aggregate Exposure

    In examining aggregate exposure, FFDCA section 408 requires that 
EPA take into account available and reliable information concerning 
exposure from the pesticide residue in the food in question, residues 
in other foods for which there are tolerances, residues in groundwater 
or surface water that is consumed as drinking water, and other non-
occupational exposures through pesticide use in gardens, lawns, or 
buildings (residential and other indoor uses). Dietary exposure to 
residues of a pesticide in a food commodity are estimated by 
multiplying the average daily consumption of the food forms of that 
commodity by the tolerance level or the anticipated pesticide residue 
level. The Theoretical Maximum Residue Contribution (TMRC) is an 
estimate of the level of residues consumed daily if each food item 
contained pesticide residues equal to the tolerance. In evaluating food 
exposures, EPA takes into account varying consumption patterns of major 
identifiable subgroups of consumers, including infants and children.The 
TMRC is a ``worst case'' estimate since it is based on the assumptions 
that food contains pesticide residues at the tolerance level and that 
100% of the crop is treated by pesticides that have established 
tolerances. If the TMRC exceeds the RfD or poses a lifetime cancer risk 
that is greater than approximately one in a million, EPA attempts to 
derive a more accurate exposure estimate for the pesticide by 
evaluating additional types of information (anticipated residue data 
and/or percent of crop treated data) which show, generally, that 
pesticide residues in most foods when they are eaten are well below 
established tolerances.
    Percent of crop treated estimates are derived from Federal and 
private market survey data. Typically, a range of estimates are 
supplied and the upper end of this range is assumed for the exposure 
assessment. By using this upper end estimate of percent of crop 
treated, the Agency is reasonably certain that exposure is not 
understated for any significant subpopulation group. Further, regional 
consumption information is taken into account through EPA's computer-
based model for evaluating the exposure of significant subpopulations 
including several regional groups, to pesticide residues. For this 
pesticide, the most highly exposed population subgroup was not 
regionally based.

II. Aggregate Risk Assessment and Determination of Safety

    Consistent with section 408(b)(2)(D), EPA has reviewed the 
available scientific data and other relevant information in support of 
this action, EPA has sufficient data to assess the hazards of clethodim 
and to make a determination on aggregate exposure, consistent with 
section 408(b)(2), for time-limited tolerances for combined residues of 
clethodim and its metabolites containing the 5-(2-
ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-
hydroxycyclohexene-3-one moieties and their sulphoxides and sulphones, 
all expressed as clethodim on alfalfa, forage at 6 ppm; alfalfa, hay at 
10 ppm; dry beans at 2 ppm; peanuts at 3 ppm; peanut, hay at 3 ppm; 
peanut, meal at 5 ppm; tomatoes at 1 ppm; tomato, puree at 2 ppm; and 
tomato, paste at 3 ppm. EPA's assessment of the dietary exposures and 
risks associated with establishing the tolerance follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
children. The nature of the toxic effects caused by clethodim are 
discussed below.
    1. Several acute toxicology studies places the technical-grade 
herbicide in Toxicity Category II.
    2. A 2-year rat chronic toxicity/carcinogenicity study found the 
compound to be noncarcinogenic to rats under the conditions of the 
study. The systemic no-observed-effect level (NOEL) was 500 ppm 
(approximately 19 milligram/kilograms/day (mg/kg/day)), and the 
systemic lowest-observed-effect-level (LOEL) was 2,500 ppm 
(approximately 100 mg/kg/day) based on the observed body weight gain, 
the increases in liver weights, and the presence of centrilobular 
hepatic hypertrophy.
    3. An 18-month mouse carcinogenicity study which showed the 
compound to be noncarcinogenic to mice under the conditions of the 
study. The systemic NOEL was 200 ppm (8 mg/kg/day), and the systemic 
LOEL was 1,000 ppm (50 mg/kg/day) based on treatment-related effects on 
survival, red cell mass, absolute and relative liver weights, and 
microscopic findings in liver and lung.
    4. A 1-year feeding study in dogs with a systemic NOEL of 1 mg/kg/
day in both sexes and an LOEL of 75 mg/kg/day based on increased 
absolute and relative liver weights, and alteration and clinical 
chemistry.
    5. A developmental toxicity study in rats with a developmental and 
maternal NOEL and LOEL of 100 and 350 mg/kg/day, respectively. The NOEL 
and LOEL for developmental toxicity were based on reductions in fetal 
body weight and increases in skeletal anomalies.
    6. A developmental toxicity study in rabbits with a maternal 
toxicity NOEL and LOEL of 25 and 100 mg/kg/day, respectively. Maternal 
toxicity was manifested as clinical signs of toxicity and reduced 
weight gain and food consumption during treatment. Developmental 
toxicity was not observed, and therefore the developmental toxicity 
NOEL was 300 mg/kg/day, highest dose tested (HDT).
    7. A two-generation reproduction study in the rat with parental 
toxicity NOEL and LOEL of 500 and 2,500 ppm (51 and 263 mg/kg/day), 
respectively, based on reductions in body weight in males, and 
decreased food consumption in both generations. The NOEL for 
reproductive toxicity was 2,500 ppm (263 mg/kg/day, HDT).
    8. A mutagenicity test with Salmonella Ames assay showed 
nonmutagenicity in three strains. Clethodim imine sulfone was negative 
for reverse gene mutation in Salmonella and E. Coli exposed up to 
10,000 ug/plate with or without activation. Clethodim was negative for 
chromosomal damage in bone marrow cells of rats treated orally up to 
toxic dose (1,500 mg/kg).

B. Toxicological Endpoints

    1. Acute toxicity. There were no effects observed in oral 
developmental toxicity studies in rats or rabbits that could be 
attributable to a single dose (exposure). Therefore, a dose and an 
endpoint were not selected.
     2. Short - and intermediate - term toxicity-- i. Dermal 
absorption. In a dermal penetration study, groups of 12 male Sprague-
Dawley rats received a single dermal application of [14C]-
clethodim in deionized water at 0.05, 0.5, or 5 mg/rat onto an area of 
10 cm2. Dermal absorption was assessed in 4 rats/dose/time 
period after 2, 10 and 24 hours post-treatment. A dermal absorption 
factor of 30% was selected for risk assessment based on the results 
observed at 10 hours in rats administered the 0.05 mg/rat dose.

[[Page 17104]]

    ii. Short-term toxicity . A dermal equivalent dose was calculated 
as 350 mg/kg/day. This dermal equivalent dose was estimated by applying 
the 30% dermal absorption (DA) rate to the oral NOEL of 100 mg/kg/day 
in a rat developmental toxicity study (oral NOEL 100 / 30% DA x 100 = 
333 mg/kg/day, dermal equivalent dose). Similarly, when the 30% DA is 
applied to the oral LOEL of 350 mg/kg/day in that study, the resulting 
dermal equivalent dose of 1167 mg/kg/day (oral LOEL 350 / 30% DA x 100) 
approximates the LOEL of 1,000 mg/kg/day established in the 21-day 
dermal study.
    In a 21-day dermal toxicity study with technical clethodim, there 
was a wide range between the mid (100 mg/kg/day) and the high (1,000 
mg/kg/day) doses. This broad range obscured the detection of a true 
NOEL which could have been anywhere in between these doses which were 
the study NOEL (100 mg/kg/day) and the LOEL (1,000 mg/kg/day). The 
Office of Pesticide's Health Effects Division's Hazard Identification 
Review Committee (HAZID Committee) also noted the 10-fold difference 
between the LOELs established with the Technical (1,000 mg/kg/day) and 
Formulated (100 mg/kg/day) products in the 21-day dermal toxicity 
studies. Therefore, based on these factors, the HAZID Committee 
calculated a dermal equivalent dose for short-term occupational and 
residential risk assessments.
    iii. Intermediate-term toxicity. A dermal equivalent dose was 
calculated as 75 mg/kg/day. This dermal equivalent dose was estimated 
by applying the 30% dermal absorption (DA) rate to the oral NOEL of 25 
mg/kg/day in the dog oral toxicity study (oral NOEL/30% DA x 100 = 75 
mg/kg/day, dermal equivalent dose).
    This dose (25 mg/kg/day) is supported by the NOEL of 30 mg/kg/day 
established in the 90-day oral feeding study in rats. In that study, 
the LOEL of 134 mg/kg/day was based on increased absolute and relative 
liver weights as well as increases in centrilobular hypertrophy. Liver 
was shown to be the target organ for clethodim-induced toxicity at 
comparable doses in two species, dogs and rats.
    Since an oral dose was identified, a dermal absorption (DA) rate of 
30% should be used for risk assessments. Application of the 30% DA is 
applied to the oral NOEL in the dog (25 mg/kg/ day) and rat (30 mg/kg/
day), and yields dermal equivalent doses of 75 and 100 mg/kg/day (25/30 
mg/kg/day / 30% x 100 = 75/100 mg/kg/day), which approximates the NOEL 
of 100 mg/kg/day established in the 21-day dermal toxicity study with 
the technical product.
     3. Chronic toxicity. EPA has established the RfD for clethodim at 
0.01 mg/kg/day. This RfD is based on alterations in hematology, a 
clinical chemistry parameter and increased absolute and relative liver 
weights at 75 mg/kg/day observed in a chronic toxicity study in dogs 
with a NOEL of 1 mg/kg/day. An uncertainty factor of 100 was used in 
calculating the RfD to account for both inter- and intra-species 
variations.
    4. Carcinogenicity. The Office of Pesticide Programs' Health 
Effects Division's Carcinogenicity Peer Review Committee (CPRC) has 
classified clethodim in Group E carcinogen (no evidence of 
carcinogenicity) under the Agency's ``Guidelines for Carcinogen Risk 
Assessment,'' published in the Federal Register of September 24, 1986 
(51 FR 33992). In its evaluation, CPRC gave consideration to the weight 
change in the 2-year feeding study in rats and the 18 month feeding 
study in mice.

C. Exposures and Risks

    1. From food and feed uses. Tolerances have been established (40 
CFR 180.458) for the combined residues of clethodim and its metabolites 
containing the 5-(2-ethylthiopropyl)cyclohexene-3-one and 5-(2-
ethylthiopropyl)-5-hydroxycyclohexene-3-one moieties and their 
sulphoxides and sulphones, all expressed as clethodim, in or on a 
variety of raw agricultural commodities. Risk assessments were 
conducted by EPA to assess dietary exposures and risks from clethodim 
as follows:
    i.  Acute exposure and risk. Acute dietary risk assessments are 
performed for a food-use pesticide if a toxicological study has 
indicated the possibility of an effect of concern occurring as a result 
of a one day or single exposure. No acute dietary endpoint was 
determined for clethodim, so an acute risk assessment was not required.
    ii. Chronic exposure and risk. The chronic dietary exposure 
analysis from food sources was conducted using the reference dose (RfD) 
of 0.01 mg/kg/day and an uncertainty factor (UF) of 100 applicable to 
all population subgroups. In conducting this chronic dietary (food) 
risk assessment, residues were used for alfalfa, dry beans, peanuts and 
tomatoes, and all other commodities with published or pending, 
permanent or time-limited clethodim tolerances. Residues were used at 
tolerance levels for some of these crops and at anticipated residue 
levels for others. Thus, this risk assessment should be viewed as 
partially refined. Further refinement using additional anticipated 
residue levels and percent crop-treated information would result in a 
lower estimate of chronic dietary exposure.
    The estimated exposure levels for existing and proposed clethodim 
uses vary between 0.001034 and 0.008411 mg/kg/day for the population 
subgroups (the U.S. population (48 states)), those for infants and 
children, females (13 to 19 years old, not pregnant and not nursing), 
and the other subgroups for which the percentage of the RfD occupied is 
greater than that occupied by the subgroup U.S. population (48 states); 
and occupied between 10% and 84% of the RfD.
    When EPA establishes, modifies, or leaves in effect a tolerance, 
section 408(b)(2)(E) authorizes EPA to use available data and 
information on the anticipated residue levels of pesticide residues in 
food and the actual levels of pesticide chemicals that have been 
measured in food. If EPA relies on such information, EPA must require 
that data be provided five years after the tolerance is established, 
modified, or left in effect, demonstrating that the levels in food are 
not above the levels anticipated. As required by section 408(b)(2)(E), 
EPA will issue a data call-in for information relating to anticipated 
residues to be submitted no later than five years from the date of 
issuance of this tolerance.
    2. From drinking water. Based on the chronic dietary (food) 
exposure and using default body weights and water consumption figures, 
chronic drinking water levels of concern (DWLOC) for drinking water 
were calcualted. To calculate the DWLOC, the chronic dietary food 
exposure (from the DRES analysis) was subtracted from the RfD.
    For chronic exposure, based on an adult body weight of 70 kg and 2L 
consumption of water per day, the level of concern from chronic 
exposure estimates for the U.S. population is 212 ppb and 1031 ppb for 
females 13 years and older, not pregnant or nursing. For infants and 
children (10 kg and 1L water/day) our level of concern for drinking 
water is 16 ppb. Agency estimates for contamination of drinking water 
from the registered uses of clethodim is 10 ppb. This level is lower 
than the chronic DWLOCs for the U.S. population (212 ppb) and females 
13 years and older, not pregnant or nursing (1,031 ppb), and infants 
and children (16 ppb). Therefore, EPA concludes with reasonable 
certainty that the chronic exposure to clethodim in surface water is 
less than our level of concern.

[[Page 17105]]

    3. From non-dietary exposure. Clethodim is currently registered for 
use on the following residential non-food sites: ornamental plants, 
wooden containers for growing plants, along driveways, patios, golf 
course turf, walkways, trails, and paths. There are no indoor uses 
registered for clethodim. It is conceivable that these outdoor uses 
could result in residential exposure. However, under current EPA 
criteria, the registered and proposed uses of clethodim would not 
constitute a chronic residential exposure scenario. Clethodim does not 
control broadleaf weeds and therefore is registered for use on edges 
and walkways, thus greatly reducing the risk of residential exposure.
    The short- and intermediate aggregate MOEs for residential 
applicators using a low pressure handwand ranged from 7,300 to 1,600. 
The post-application aggregate short- and intermediate-term MOEs for 
the U.S. population ranged from 520 to 110. The post-application 
aggregate short- and intermediate-term MOEs for infants/children range 
from 540 to 115. Short- and intermediate-term aggregate exposure takes 
into account chronic dietary exposure plus indoor and outdoor 
residential exposures. These exposure assessments assumed the maximum 
application rate for turf and garden uses and two hours as the duration 
of exposure, and a 20% dislodgeable foliar residue. These assumptions 
are considered conservative and protective.
    4. Cumulative exposure to substances with common mechanism of 
toxicity. Section 408(b)(2)(D)(v) requires that, when considering 
whether to establish, modify, or revoke a tolerance, the Agency 
consider ``available information'' concerning the cumulative effects of 
a particular pesticide's residues and ``other substances that have a 
common mechanism of toxicity.'' The Agency believes that ``available 
information'' in this context might include not only toxicity, 
chemistry, and exposure data, but also scientific policies and 
methodologies for understanding common mechanisms of toxicity and 
conducting cumulative risk assessments. For most pesticides, although 
the Agency has some information in its files that may turn out to be 
helpful in eventually determining whether a pesticide shares a common 
mechanism of toxicity with any other substances, EPA does not at this 
time have the methodologies to resolve the complex scientific issues 
concerning common mechanism of toxicity in a meaningful way. EPA has 
begun a pilot process to study this issue further through the 
examination of particular classes of pesticides. The Agency hopes that 
the results of this pilot process will increase the Agency's scientific 
understanding of this question such that EPA will be able to develop 
and apply scientific principles for better determining which chemicals 
have a common mechanism of toxicity and evaluating the cumulative 
effects of such chemicals. The Agency anticipates, however, that even 
as its understanding of the science of common mechanisms increases, 
decisions on specific classes of chemicals will be heavily dependent on 
chemical specific data, much of which may not be presently available.
    Although at present the Agency does not know how to apply the 
information in its files concerning common mechanism issues to most 
risk assessments, there are pesticides as to which the common mechanism 
issues can be resolved. These pesticides include pesticides that are 
toxicologically dissimilar to existing chemical substances (in which 
case the Agency can conclude that it is unlikely that a pesticide 
shares a common mechanism of activity with other substances) and 
pesticides that produce a common toxic metabolite (in which case common 
mechanism of activity will be assumed).
    EPA does not have, at this time, available data to determine 
whether clethodim has a common mechanism of toxicity with other 
substances or how to include this pesticide in a cumulative risk 
assessment. Unlike other pesticides for which EPA has followed a 
cumulative risk approach based on a common mechanism of toxicity, 
clethodim does not appear to produce a toxic metabolite produced by 
other substances. For the purposes of this tolerance action, therefore, 
EPA has not assumed that clethodim has a common mechanism of toxicity 
with other substances.

D. Aggregate Risks and Determination of Safety for U.S. Population

    1. Acute risk. There were no effects observed in oral developmental 
toxicity studies in rats or rabbits that could be attributable to a 
single dose (exposure). Therefore, a dose and an endpoint were not 
selected, and EPA concludes that there is a reasonable certainty that 
no harm will result from aggregate acute exposure to clethodim 
residues.
    2. Chronic risk. Using the ARC exposure assumptions described 
above, EPA has concluded that aggregate exposure to clethodim from food 
will utilize 39% of the RfD for the U.S. population. The major 
identifiable subgroup with the highest aggregate exposure is children 
one to six years of age and is discussed below. EPA generally has no 
concern for exposures below 100% of the RfD because the RfD represents 
the level at or below which daily aggregate dietary exposure over a 
lifetime will not pose appreciable risks to human health. Despite the 
potential for exposure to clethodim in drinking water and from non-
dietary, non-occupational exposure, EPA does not expect the aggregate 
exposure to exceed 100% of the RfD. EPA concludes that there is a 
reasonable certainty that no harm will result from aggregate chronic 
exposure to clethodim residues.
    3. Short- and intermediate-term risk. Short- and intermediate-term 
aggregate exposure takes into account chronic dietary food and water 
(considered to be a background exposure level) plus indoor and outdoor 
residential exposure.
    Clethodim is registered for uses that could result in short- and 
intermediate-term exposures. The short- and intermediate aggregate 
margins of exposure (MOEs) for residential applicators using a low 
pressure handwand ranged from 7,300 to 1,600. The postapplication 
aggregate short- and intermediate-term MOEs for the U.S. population 
ranged from 520 to 110. The postapplication aggregate short- and 
intermediate-term MOEs for infants/children range from 540 to 115. 
Short- and intermediate-term aggregate exposure takes into account 
chronic dietary exposure plus indoor and outdoor residential exposures. 
These exposure assessments assumed the maximum application rate for 
turf and garden uses and two hours as the duration of exposure, and a 
20% dislodgeable foliar residue. These assumptions are considered 
conservative and protective. Short- and intermediate term MOEs for 
occupational workers ranged from 620 for aerial mixer/loaders to 60,000 
for ground applicators. These estimates do not exceed EPA's level of 
concern. EPA concludes that there is a reasonable certainty that no 
harm will result from aggregate short- and intermediate-term exposure 
to clethodim residues.

E. Aggregate Cancer Risk for U.S. Population

    Clethodim has been classified as a Group E chemical (no evidence of 
carcinogenicity), and EPA concludes that there is a reasonable 
certainty that no harm will result from aggregate exposure to clethodim 
residues.

F. Aggregate Risks and Determination of Safety for Infants and Children

    1. Safety factor for infants and children-- i. In general. In 
assessing the

[[Page 17106]]

potential for additional sensitivity of infants and children to 
residues of clethodim, EPA considered data from developmental toxicity 
studies in the rat and rabbit and a two-generation reproduction study 
in the rat. The developmental toxicity studies are designed to evaluate 
adverse effects on the developing organism resulting from maternal 
pesticide exposure gestation. Reproduction studies provide information 
relating to effects from exposure to the pesticide on the reproductive 
capability of mating animals and data on systemic toxicity.
    FFDCA section 408 provides that EPA shall apply an additional 
tenfold margin of safety for infants and children in the case of 
threshold effects to account for pre-and post-natal toxicity and the 
completeness of the database unless EPA determines that a different 
margin of safety will be safe for infants and children. Margins of 
safety are incorporated into EPA risk assessments either directly 
through use of a MOE analysis or through using uncertainty (safety) 
factors in calculating a dose level that poses no appreciable risk to 
humans. EPA believes that reliable data support using the standard 
uncertainty factor (usually 100 for combined inter- and intra-species 
variability)) and not the additional tenfold MOE/uncertainty factor 
when EPA has a complete data base under existing guidelines and when 
the severity of the effect in infants or children or the potency or 
unusual toxic properties of a compound do not raise concerns regarding 
the adequacy of the standard MOE/safety factor.
    ii. Developmental toxicity studies. In a prenatal developmental 
toxicity study in Sprague-Dawley rats, clethodim (82.6%) was 
administered at doses of 0, 10, 100, 350, or 700 mg/kg/day by gavage in 
10 mg/kg of 0.7% carboxy methylcellulose and Tween 80 on gestation days 
6-15. For maternal toxicity, the NOEL was 100 mg/kg/day and the LOEL 
was 350 mg/kg/day based upon decreased body weight gain and clinical 
signs of toxicity (salivation). The developmental NOEL was 100 mg/kg/
day and the developmental LOEL was 350 mg/kg/day, based upon reductions 
in fetal body weight and an increase in the incidence of skeletal 
anomalies.
    A prenatal developmental toxicity study was conducted in pregnant 
New Zealand white rabbits in which clethodim (82.6%) was administered 
by gavage in 5 ml/kg at doses of 0, 25, 100, or 300 mg/kg/day in 0.7% 
carboxy methylcellulose and Tween 80 on gestation days 7-19. For 
maternal toxicity, the NOEL was 25 mg/kg/day and the LOEL was 100 mg/
kg/day, based on clinical signs of toxicity (dried feces and blood in 
the cage pan) and reduced body weight and food consumption during 
treatment. There was no developmental toxicity noted. For developmental 
toxicity, the NOEL was  300; a LOEL was not established.
    iii. Reproductive toxicity study. In a two-generation reproductive 
study, Sprague-Dawley rats received clethodim (83.2%) in the diet at 0, 
5, 20, 500, or 2,500 ppm. The parental systemic NOEL was 500 ppm (51 
mg/kg/day) and the parental systemic LOEL was 2,500 ppm (263 mg/kg/
day), based on decreased body weights (particularly in males) and food 
consumption for both generations. There were no effects on 
reproduction, nor was there evidence of toxicity to the offspring 
(offspring NOEL  2,500 ppm).
    iv. Pre- and post-natal sensitivity. The data base is complete. The 
oral perinatal and prenatal data demonstrated no indication of 
increased sensitivity of rats or rabbits to in utero exposure to 
clethodim. Therefore, EPA concludes that reliable data show that the 
standard uncertainty factor of 100 will be safe for infants and 
children.
    2. Acute risk. There were no effects observed in oral developmental 
toxicity studies in rats or rabbits that could be attributable to a 
single dose (exposure). Therefore, a dose and an endpoint were not 
selected, and EPA concludes that there is a reasonable certainty that 
no harm will result from aggregate acute exposure to clethodim 
residues.
    3. Chronic risk. Using the conservative exposure assumptions 
described above, EPA has concluded that aggregate exposure to clethodim 
from food will utilize 45% of the RfD for non-nursing infants less than 
one year old, and 84% for children ages one through six years of age. 
EPA generally has no concern for exposures below 100% of the RfD 
because the RfD represents the level at or below which daily aggregate 
dietary exposure over a lifetime will not pose appreciable risks to 
human health. Despite the potential for exposure to clethodim in 
drinking water and from non-dietary, non-occupational exposure, EPA 
does not expect the aggregate exposure to exceed 100% of the RfD. EPA 
concludes that there is a reasonable certainty that no harm will result 
to infants and children from aggregate exposure to clethodim residues.
    4. Short- or intermediate-term risk. The postapplication aggregate 
short- and intermediate-term MOEs for infants/children range from 540 
to 115. Short- and intermediate-term aggregate exposure takes into 
account chronic dietary exposure plus indoor and outdoor residential 
exposures. These exposure assessments assumed the maximum application 
rate for turf and garden uses and two hours as the duration of 
exposure, and a 20% dislodgeable foliar residue. These assumptions are 
considered conservative and protective. These estimates do not exceed 
EPA's level of concern. EPA concludes that there is a reasonable 
certainty that no harm will result from aggregate short- and 
intermediate-term exposure to clethodim residues.

III. Other Considerations

A. Metabolism In Plants and Animals

    The nature of clethodim residues in plants, ruminants, and poultry 
is adequately understood for the purposes of these subject petitions. 
The residues of concern are as defined in 40 CFR 180.485(b).

B. Analytical Enforcement Methodology

    Analytical methods are available for enforcement. Method EPA-RM-
26D-2 [HPLC-UV], ``Confirmatory Method for the Determination of 
Clethodim and Clethodim Metabolites in Crops, Animal Tissues, and Mail 
and Eggs,'' which distinguishes clethodim residues from residues of the 
structurally similar herbicide sethoxydim, and Method RM-26B-2 [GLC-
FPD-S], ``Analytical Method for the Determination of Clethodim 
Residues,'' the common moiety method, have undergone successful EPA 
Method Validation. Revisions to EPA-RM-26D-2 are requested prior to 
establishment of permanent tolerances on these subject crops. The 
method may be obtained from: Calvin Furlow, PRRIB, IRSD, (7502C), 
Office of Pesticide Programs, Environmental Protection Agency, 401 M 
St., SW., Washington, DC 20460. Office location and telephone number: 
Rm. 119FF, CM #2, 1921 Jefferson Davis Hwy., Arlington, VA 22202, (703-
305-5229).

C. Magnitude of Residues

    The crop field trial data are adequate for the purposes of these 
time-limited tolerances. To support future permanent tolerances, Valent 
U.S.A. Corp. must submit three additional dry bean field trials from 
Region 5, four additional peanut field trials from Region 2, and four 
additional tomato field trials from California, each conducted at the 
maximum use rates and proposed pre-harvest intervals. Field trial 
regions are defined in EPA OPPTS Guideline 860.1500.

D. International Residue Limits

    There are no Codex, Canadian or Mexican tolerances or maximum 
residue limits established for clethodim

[[Page 17107]]

on tomatoes, alfalfa, peanuts, or dry beans. There are no conflicts 
between this proposed action and international residue limits.

E. Rotational Crop Restrictions

    A confined rotational crop study of [ring-4,6-14C]-
clethodim with carrots, lettuce, and wheat was reported. Results 
indicate there is no need for field rotational crop trials.

IV. Conclusion

    Therefore, the time-limited tolerances are is established for 
combined residues of clethodim and its metabolites containing the 5-(2-
ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-
hydroxycyclohexene-3-one moieties and their sulphoxides and sulphones, 
all expressed as clethodim in alfalfa, forage at 6 ppm; alfalfa, hay at 
10 ppm; dry beans at 2 ppm; peanuts at 3 ppm; peanut, hay at 3 ppm; 
peanut, meal at 5 ppm; tomatoes at 1 ppm; tomato, puree at 2 ppm; and 
tomato, paste at 3 ppm.

V. Objections and Hearing Requests

    The new FFDCA section 408(g) provides essentially the same process 
for persons to ``object'' to a tolerance regulation issued by EPA under 
new section 408(e) and (l)(6) as was provided in the old section 408 
and in section 409. However, the period for filing objections is 60 
days, rather than 30 days. EPA currently has procedural regulations 
which govern the submission of objections and hearing requests. These 
regulations will require some modification to reflect the new law. 
However, until those modifications can be made, EPA will continue to 
use those procedural regulations with appropriate adjustments to 
reflect the new law.
    Any person may, by June 8, 1998, file written objections to any 
aspect of this regulation and may also request a hearing on those 
objections. Objections and hearing requests must be filed with the 
Hearing Clerk, at the address given above (40 CFR 178.20). A copy of 
the objections and/or hearing requests filed with the Hearing Clerk 
should be submitted to the OPP docket for this rulemaking. The 
objections submitted must specify the provisions of the regulation 
deemed objectionable and the grounds for the objections (40 CFR 
178.25). Each objection must be accompanied by the fee prescribed by 40 
CFR 180.33(i). If a hearing is requested, the objections must include a 
statement of the factual issues on which a hearing is requested, the 
requestor's contentions on such issues, and a summary of any evidence 
relied upon by the requestor (40 CFR 178.27). A request for a hearing 
will be granted if the Administrator determines that the material 
submitted shows the following: There is genuine and substantial issue 
of fact; there is a reasonable possibility that available evidence 
identified by the requestor would, if established, resolve one or more 
of such issues in favor of the requestor, taking into account 
uncontested claims or facts to the contrary; and resolution of the 
factual issues in the manner sought by the requestor would be adequate 
to justify the action requested (40 CFR 178.32). Information submitted 
in connection with an objection or hearing request 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 information that does not contain CBI must be 
submitted for inclusion in the public record. Information not marked 
confidential may be disclosed publicly by EPA without prior notice.

VI. Public Docket

    EPA has established a record for this rulemaking under docket 
control number [OPP-300620] (including any comments and data submitted 
electronically). A public version of this record, including printed, 
paper versions of electronic comments, which does not include any 
information claimed as CBI, is available for inspection from 8:30 a.m. 
to 4 p.m., Monday through Friday, excluding legal holidays. The public 
record is located in Room 119 of the Public Information and Records 
Integrity Branch, Information Resources and Services Division (7502C), 
Office of Pesticide Programs, Environmental Protection Agency, Crystal 
Mall #2, 1921 Jefferson Davis Hwy., Arlington, VA.
    Electronic comments may be sent directly to EPA at:
    [email protected].


    Electronic comments must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption.
    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 any copies of objections and hearing requests 
received electronically 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. The 
official rulemaking record is the paper record maintained at the 
Virginia address in ``ADDRESSES'' at the beginning of this document.

VII. Regulatory Assessment Requirements

    This final rule establishes time-limited tolerances under FFDCA 
section 408(d) in response to a petition submitted to the Agency. The 
Office of Management and Budget (OMB) has exempted these types of 
actions from review under Executive Order 12866, entitled Regulatory 
Planning and Review (58 FR 51735, October 4, 1993). This final rule 
does not contain any information collections subject to OMB approval 
under the Paperwork Reduction Act (PRA), 44 U.S.C. 3501 et seq., or 
impose any enforceable duty or contain any unfunded mandate as 
described under Title II of the Unfunded Mandates Reform Act of 1995 
(UMRA) (Pub. L. 104-4). Nor does it require any prior consultation as 
specified by Executive Order 12875, entitled Enhancing the 
Intergovernmental Partnership (58 FR 58093, October 28, 1993), or 
special considerations as required by Executive Order 12898, entitled 
Federal Actions to Address Environmental Justice in Minority 
Populations and Low-Income Populations (59 FR 7629, February 16, 1994), 
or require OMB review in accordance with Executive Order 13045, 
entitled Protection of Children from Environmental Health Risks and 
Safety Risks (62 FR 19885, April 23, 1997).
    In addition, since these tolerances and exemptions that are 
established on the basis of a petition under FFDCA section 408(d), such 
as the time-limited tolerances in this final rule, do not require the 
issuance of a proposed rule, the requirements of the Regulatory 
Flexibility Act (RFA) (5 U.S.C. 601 et seq.) do not apply. 
Nevertheless, the Agency has previously assessed whether establishing 
tolerances, exemptions from tolerances, raising tolerance levels or 
expanding exemptions might adversely impact small entities and 
concluded, as a generic matter, that there is no adverse economic 
impact. The factual basis for the Agency's generic certification for 
tolerance actions published on May 4, 1981 (46 FR 24950) and was 
provided to the Chief Counsel for Advocacy of the Small Business 
Administration.

VIII. Submission to Congress and the Comptroller General

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement

[[Page 17108]]

Fairness Act of 1996, generally provides that before a rule may take 
effect, the agency promulgating the rule must submit a rule report, 
which includes a copy of the rule, to each House of the Congress and to 
the Comptroller General of the United States. EPA will submit a report 
containing this rule and other required information to the U.S. Senate, 
the U.S. House of Representatives, and the Comptroller General of the 
United States prior to publication of the rule in the Federal Register. 
This rule is not a ``major rule'' as defined by 5 U.S.C. 804(2).

List of Subjects

40 CFR Part 180

    Environmental protection, Administrative practice and procedure, 
Agricultural commodities, Pesticides and pests, Reporting and 
recordkeeping requirements.

40 CFR Part 185

    Environmental protection, Food additives, Pesticides and pests.

40 CFR Part 186

    Environmental protection, Animal feeds, Pesticides and pests.

    Dated: April 3, 1998.

James Jones,

Director, Registration Division, Office of Pesticide Programs.
    Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

    1. In part 180:
    a. The authority citation for part 180 continues to read as 
follows:

    Authority: 21 U.S.C. 346a and 371.

    b. Section 180.458 is amended as follows:
    i. By adding a heading to paragraph (a) and designating the text as 
paragraph (a)(1).
    ii. By adding paragraph (a)(2).
    iii. By redesignating paragraph (b) as paragraph (a)(3).
    iv. By adding with headings and reserving paragraphs (b), (c), and 
(d).
    The added text reads as follows:


Sec. 180.458  Clethodim ((E)-()-2-[1-[[(3-chloro-2-
propenyl)oxy]imino]propyl]-5-[2(ethylthio)propyl]-3-hydroxy-2-
cyclohexen-1-one); tolerances for residues.

    (a) General. * * *
    (2) Time-limited tolerances are established for the combined 
residues of clethodim ((E)-()-2-[1-[[(3-chloro-2-
propenyl)oxy]imino]propyl]-5-[2- (ethylthio)propyl]-3-hydroxy-2-
cyclohexen-1-one) and its metabolites containing the 5-(2-
ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-
hydroxycyclohexene-3-one moieties and their sulphoxides and sulphones, 
expressed as clethodim, in or on the following raw agricultural 
commodities:

                                                                        
------------------------------------------------------------------------
                                                             Expiration/
                   Commodity                     Parts per    Revocation
                                                  million        Date   
------------------------------------------------------------------------
Alfalfa, forage...............................            6      4/30/01
Alfalfa, hay..................................           10      4/30/01
Dry beans.....................................            2      4/30/01
Peanut, hay...................................            3      4/30/01
Peanut, meal..................................            5      4/30/01
Peanuts.......................................            3      4/30/01
Tomatoes......................................            1      4/30/01
Tomato, paste.................................            3      4/30/01
Tomato, puree.................................            2      4/30/01
------------------------------------------------------------------------

 * * * * *
    (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]

PART 185--[AMENDED]

    2. In part 185:
    a. The authority citation for part 185 continues to read as 
follows:

    Authority: 21 U.S.C. 346a and 348.

Sec. 185.1075  [Removed]

    b. In Sec. 185.1075:
    i. By transferring the text and table to Sec. 180.458 and 
redesignating as paragraph (a)(4).
    ii. The remainder of Sec. 185.1075 is removed.

PART 186--[AMENDED]

    3. In part 186:
    a. The authority citation for part 186 continues to read as 
follows:

    Authority: 21 U.S.C. 342, 348, and 701.

Sec. 186.1075  [Removed]

    b. In Sec. 186.1075:
    i. Paragraphs (a) and (b) are transferred to Sec. 180.458 and 
redesignated as paragraphs (a)(5) and (a)(6) respectively.
    ii. The remainder of Sec. 186.1075 is removed.

[FR Doc. 98-9392 Filed 4-7--98; 8:45 am]
BILLING CODE 6560-50-F