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clethodim (Select) Pesticide Petition Filing 11/97


[Federal Register: December 3, 1997 (Volume 62, Number 232)]
[Notices]               
[Page 63942-63951]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03de97-74]

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ENVIRONMENTAL PROTECTION AGENCY

[PF-780; FRL-5756-1]

 
Notice of Filing of Pesticide Petitions

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: This notice announces the initial filing of pesticide 
petitions proposing the establishment of regulations for residues of 
certain pesticide chemicals in or on various food commodities.
DATES: Comments, identified by the docket control number PF-780, must 
be received on or before January 2, 1998.
ADDRESSES: By mail submit written comments to: Public Information and 
Records Integrity Branch, Information Resources and Services Division 
(7502C), Office of Pesticides Programs, Environmental Protection 
Agency, 401 M St., SW., Washington, DC 20460. In person bring comments 
to: Rm. 1132, CM #2, 1921 Jefferson Davis Highway, Arlington, VA.
    Comments and data may also be submitted electronically to: opp-
docket@epamail.epa.gov. Follow the instructions under ``SUPPLEMENTARY 
INFORMATION.'' No confidential business information should be submitted 
through e-mail.
    Information submitted as a comment concerning this document may be 
claimed confidential by marking any part or all of that information as 
``Confidential Business Information'' (CBI). CBI should not be 
submitted through e-mail. Information marked as CBI will not be 
disclosed except in accordance with procedures set forth in 40 CFR part 
2. A copy of the comment that does not contain CBI must be submitted 
for inclusion in the public record. Information not marked confidential 
may be disclosed publicly by EPA without prior notice. All written 
comments will be available for public inspection in Rm. 1132 at the 
address given above, from 8:30 a.m. to 4 p.m., Monday through Friday, 
excluding legal holidays.

FOR FURTHER INFORMATION CONTACT: The product manager listed in the 
table below:

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                                   Office location/                     
        Product Manager            telephone number          Address    
------------------------------------------------------------------------
Joanne Miller (PM 23).........  Rm. 237, CM #2, 703-    1921 Jefferson  
                                 305-6224, e-            Davis Hwy,     
                                 mail:miller.joanne@ep   Arlington, VA  
                                 amail.epa.gov.                         
James Tompkins (PM 25)........  Rm. 239, CM #2, 703-    1921 Jefferson  
                                 305-5697, e-mail:       Davis Hwy,     
                                 tompkins.james@epamai   Arlington, VA. 
                                 l.epa.gov.                             
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SUPPLEMENTARY INFORMATION: 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.
    The official record for this notice of filing, as well as the 
public version, has been established for this notice of filing under 
docket control number [PF-780] (including comments and data submitted 
electronically as described below). 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 official record is located at the address in 
``ADDRESSES'' at the beginning of this document.
    Electronic comments can be sent directly to EPA at:
    opp-docket@epamail.epa.gov


    Electronic comments must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption. Comment and data 
will also be accepted on disks in Wordperfect 5.1 file format or ASCII 
file format. All comments and data in electronic form must be 
identified by the docket number (insert docket number) and appropriate 
petition number. Electronic comments on notice may be filed online at 
many Federal Depository Libraries.

List of Subjects

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

    Dated: November 21, 1997

Peter Caulkins,
Acting 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.

1. Valent U.S.A. Corporation

PP 7F4873

    EPA has received a pesticide petition (PP 7F4873) from Valent 
U.S.A. Corporation, 1333 N. California Blvd., Walnut Creek, CA 94596. 
proposing pursuant to section 408(d) of the Federal Food, Drug and 
Cosmetic Act, 21 U.S.C. 346a(d), to amend 40 CFR part 180 by 
establishing a tolerance for residues of clethodim in or on the raw 
agricultural commodities tuberous and corm vegetables (crop subgroup 1-
C) at 1.0 parts per million (ppm), potato flakes/granules at 2.0 ppm, 
sunflower seed at 5.0 ppm, sunflower meal at 10.0 ppm, canola seed at 
0.5 ppm, and canola meal at 1.5 ppm. The crop subgroup 1-C tolerance 
should replace the 0.5 ppm tolerance that already exists for clethodim 
in/or potato tubers which was based on data from Canada. The

[[Page 63943]]

proposed analytical method for these commodities is EPA-RM-26D-3, a 
high-performance liquid chromatography (HPLC) method. 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 supports granting of the petition. Additional data 
may be needed before EPA rules on the petition.

A. Residue Chemistry

    1. Plant metabolism. Clethodim is used for postemergent control of 
grasses in a wide variety of crops including cotton, soybeans, sugar 
beets, onions, tomatoes, etc. Plant metabolism studies have been 
performed in carrots, soybeans, and cotton. Studies were performed with 
clethodim radiolabeled in the ring structure and in the side chain to 
follow both parts of the molecule.
    The major metabolic pathway in plants is initial sulfoxidation to 
form clethodim sulfoxide followed by further sulfoxidation to form 
clethodim sulfone; elimination of the chloroallyloxy side chain to give 
the imine sulfoxide and sulfone; and hydroxylation to form the 5-OH 
sulfoxide and 5-OH sulfone. Clethodim sulfoxide and clethodim sulfone 
conjugates were also detected as major or minor metabolites, depending 
on plant species and subfractions. Once cleaved from clethodim, the 
chloroallyloxy moiety udergoes extensive metabolism to eliminate the 
chlorine atom and incorporate the three-carbon moieties into natural 
plant components.
    Based on these metabolism studies, the residues of concern in crops 
are clethodim and its metabolites containing the cyclohexene moiety, 
and their sulfoxides and sulfones.
    2. Analytical method. Adequate analytical methodology is available 
for detecting and measuring levels of clethodim and its metabolites in 
crops. For most commodities, the primary enforcement method is EPA-RM-
26D-3, an HPLC method capable of distinguishing clethodim from the 
structurally related herbicide sethoxydim. However, for milk natural 
interferences prevent adequate quantitation of clethodim moieties and 
the common-moiety method (RM-26B-2) is the primary enforcement method 
with EPA-RM-26D-3 as the secondary method if needed to determine 
whether residues are clethodim or sethoxydim. Both of these methods 
have successfully undergone petition method validations at EPA.
    3. Magnitude of residues. Clethodim is the active ingredient in 
SELECT 2 EC Herbicide (EPA Reg. No. 59639-3) and SELECT Herbicide (also 
known as PRISM and ENVOY Herbicides, EPA Reg. No. 59639-78). Tolerances 
have been established for residues in cotton, soybean, sugar beet, 
onion (dry bulb), and animal commodities, and tolerances are expected 
soon for alfalfa, peanut, dry bean, and tomato commodities. A summary 
of available field residue data for the pending tolerances on tuberous 
and corm vegetables (crop subgroup 1-C), sunflower, and canola 
commodities is presented below.
    In 17 field trials, potatoes were treated with two post-emergent 
applications of 0.25 lb. a.i./A each, approximately 14-days apart, and 
harvested approximately 30 days after the last application. Trials were 
performed in EPA Regions 1, 2, 3, 5, 9, 10, and 11. Residues for potato 
tuber samples ranged from < 0.1 ppm to 0.80 ppm total clethodim. The 
highest average field trial (HAFT) residue was 0.775 ppm. The average 
residue value for all trials, excluding samples less than the limit of 
detection, was 0.42 ppm. Two processing studies were also performed for 
potatoes. Residues were found to concentrate in flakes, but not wet 
peel or chips. The average concentration factor for flakes was 2.4. 
Since potato is the only representative crop for crop subgroup 1-C per 
40 CFR 180.41, these data support time-limited tolerances of 1.0 ppm in 
tuberous and corm vegetables (crop subgroup 1-C) and 2.0 ppm in flakes/
granules.
    In 8 field trials, sunflowers were treated with two post-emergent 
applications of 0.25 lb. a.i./A each. Sunflower seeds were harvested 56 
to 72 days after the last application. Trials were performed in EPA 
Regions 5, 7, and 8. Residues for sunflower seed samples ranged from 
0.46 ppm to 4.4 ppm total clethodim. The highest average field trial 
(HAFT) residue was 4.2 ppm. The average residue level was 1.6 ppm. A 
processing study was also performed for sunflowers. Residues were found 
to concentrate in meal, but not in refined oil. The concentration 
factor for meal was 2.1. These data support tolerances of 5.0 ppm in 
sunflower seed and 10.0 ppm in sunflower meal.
    In 18 field trials, canola or rape was treated with one post-
emergent application of 0.11 to 0.32 lb. a.i./A and harvested 
approximately 70 to 98 days after the application. Most of the trials 
were performed in Canada in growing regions adjacent to the U.S. areas 
where canola is grown. These data were used to support a maximum 
residue level in Canada and are being cited in order to harmonize 
maximum residue levels between the U.S. and Canada and remove the 
existing trade barrier. Residues in canola seed samples ranged from < 
0.05 ppm to 0.54 ppm. The highest average field trial (HAFT) residue 
was 0.505 ppm. The average residue value for all trials, including 
samples less than the limit of detection at one-half the limit, was 
0.162 ppm. A processing study was also performed for canola and 
residues were found to concentrate in meal, but not in crude oil. Since 
the highest residues were the result of application rates higher than 
those proposed for the U.S., these data support tolerances of 0.5 ppm 
in canola seed and 1.5 ppm in canola oil.

B. Toxicological Profile

    1. Acute toxicity. Clethodim Technical is slightly toxic to animals 
following acute oral (Toxicity Category III), dermal (Toxicity Category 
IV), or inhalation exposure (Toxicity Category IV under current 
guideline interpretation). Clethodim is a moderate eye irritant 
(Category III), a severe skin irritant (Category II), and does not 
cause skin sensitization in the modified Buehler test in guinea pigs. 
In addition, an acute oral no-observed effect level (NOEL) has been 
determined in rats to be 300 milligrams/kilograms (mg/kg). Since this 
NOEL is significantly higher than the lowest chronic NOEL of 1 mg/kg/
day, chronic exposures are expected to be of the most concern and this 
summary will focus on repeated exposures.
    2. Genotoxicty. Clethodim Technical did not induce gene mutation in 
microbial in vitro assays. A weak response in an in vitro assay for 
chromosome aberrations was not confirmed when clethodim was tested in 
an in vivo cytogenetics assay up to the maximally tolerated dose level, 
nor was the response observed in vitro using technical material of a 
higher purity. No evidence of unscheduled DNA synthesis was seen 
following in vivo exposure up to a dose level near the LD<INF>50</INF> 
(1.5 g/kg). This evidence indicates that clethodim does not present a 
genetic hazard to intact animal systems.
    3. Reproductive and developmental toxicity. No reproductive 
toxicity was observed with Clethodim Technical at feeding levels up to 
2,500 ppm. Developmental toxicity was observed in two rodent species, 
but only at maternally toxic dose levels. In rats, the developmental 
NOEL was 300 mg/kg/day while the maternal toxicity NOEL was only 150 
mg/kg/day. In rabbits, the developmental NOEL was >300 mg/kg/day and 
the maternal NOEL was only 25 mg/kg/day. Valent therefore does not

[[Page 63944]]

consider clethodim to be a reproductive or developmental hazard. These 
studies also indicate that clethodim does not adversely affect 
endocrine function.
    4. Subchronic toxicity. High doses of Clethodim Technical cause 
decreased body weights, increased liver size (increased weight and cell 
hypertrophy), and anemia (decreased erythrocyte counts, hemoglobin, or 
hematocrit) in rats and dogs. No observable effect levels have been 
determined to be 100 mg/kg/day for a 4-week dermal study in rats, 200 
to 1,000 ppm for 4- or 5-week feeding studies in rats or mice, 500 ppm 
in a 13-week feeding study in rats, and 25 mg/kg/day in a 90-day oral 
study in dogs.
    5. Chronic toxicity and oncogenicity. In chronic studies conducted 
in rats, mice, and dogs, compound-related effects noted at high doses 
included decreased body weight, increased liver size (liver weight and 
hypertrophy), and anemia (decreased hemoglobin, hematocrit, and 
erythrocyte count). Bone marrow hyperplasia was observed in dogs at the 
highest dose tested. No treatment-related increases in incidence of 
neoplasms were observed in any study. Chronic NOELs were 200 ppm for an 
18-month feeding study in mice and 500 ppm for a 24-month study in 
rats. The lowest NOEL is from the 1-year oral dog study and is 1 mg/kg/
day clethodim technical. Based on this study and a 100-fold safety 
factor, the reference dose (RfD) for clethodim was determined to be 
0.01 mg/kg/day. Valent believes that clethodim is not carcinogenic. 
These studies also indicate that clethodim does not adversely affect 
endocrine function.
    6. Animal metabolism. The in vivo metabolism of clethodim in rats 
was tested at a high dose (468 mg/kg), low dose (4.4 mg/kg), and a low 
dose (4.8 mg/kg) following 14-days of treatment with Clethodim 
Technical. A single oral dose of [14C]-clethodim was given to each rat 
and expired carbon dioxide and excreta were collected over the next 2- 
and 7-days, respectively, to determine radiolabel recovery. Several 
organs and tissues, and the remaining carcass, were collected after 
sacrifice to determine radiolabel recovery. In all treatment groups, 
nearly all of the radiolabel was eliminated in the urine (87-93%), 
feces (9-17%), and carbon dioxide (0.5-1%) and less than 1% of the dose 
was recovered in the organs and tissues after 7- days.
    Elimination was rapid as most of the recovered dose was eliminated 
within 48 hours. The low dose groups eliminated clethodim slightly 
faster than the high dose group, and repeated exposure to clethodim 
prior to radiolabel dosing did not affect the rate of elimination or 
distribution of recovered radiolabel. There were no apparent sex 
differences with respect to elimination or distribution of metabolites.
    The primary excretory metabolites were identified as clethodim 
sulfoxide (48-63%), clethodim S-methyl sulfoxide (6-12%), clethodim 
imine sulfoxide (7-10%), and clethodim 5-hydroxy sulfoxide (3-5%). 
Minor metabolites included clethodim oxazole sulfoxide (2-3%), 
clethodim trione sulfoxide (1%), clethodim (1%), clethodim 5-hydroxy 
sulfone (0.3-1%), clethodim sulfone (0.1-1%), aromatic sulfone (0.2-
0.7%), and S-methyl sulfone (0-0.4%).
    7. Dermal penetration. The dermal penetration of SELECT 2 EC 
Herbicide, the end-use product, was tested on unabraded, shaved skin of 
rats. Single doses of approximately 0.05, 0.5, and 5.0 mg of 
radiolabeled (14C-clethodim) SELECT 2 EC Herbicide, were applied 
topically to 10 cm<SUP>2</SUP> sites on the dorsal trunk. After 2, 10, 
or 24 hours, urine, feces, volatiles, scrubbings of the skin, skin at 
treatment site, blood, several tissues, and the carcass were collected 
and counted for radioactivity. Clethodim was found to be slowly 
absorbed through the skin in a time-dependent manner. The percent of 
dose absorbed increased with length of exposure and decreased with 
increasing dose. 10-hour absorption rates ranged from 7.5% to 30.0%. 
Most of the absorbed material was found in the urine and carcass, and 
most of the unabsorbed material was found in the skin scrubbings 
indicating that material was still on the skin surface.
    8. Metabolite toxicology. 2 metabolites of clethodim, clethodim 
imine sulfone (RE-47719) and clethodim 5-hydroxy sulfone (RE-51228), 
have been tested in toxicity screening studies to evaluate the 
potential impact of these metabolites on the toxicity of clethodim. In 
general, these metabolites were found to be less toxic than Clethodim 
Technical for acute and oral toxicity studies; reproduction and 
teratology screening studies; and several mutagenicity studies.

C. Aggregate Exposure

    1. Dietary exposure--i. Food. Clethodim is approved for use in the 
production of commercial agricultural crops including cotton, soybeans, 
sugar beets, and onions (dry bulb). Approval is expected soon for 
several additional crops. Dietary exposures are expected to represent 
the major route of exposure to the public. Since chronic exposures are 
of more concern than acute exposures for clethodim, this summary will 
focus primarily on chronic issues. Chronic dietary assessments for 
clethodim have been conducted by the registrant for all currently 
approved crops, all pending crops, and the crops proposed in this 
petition (tuberous and corm vegetables, sunflower, and canola).
    In Valent's assessment, anticipated residues were used for all crop 
and animal commodities. Anticipated residue levels were the mean levels 
found in crop field trial data after treatment with the maximum 
recommended rate and harvested at minimum allowable intervals. These 
values are, therefore, slightly conservative. An assessment was 
performed assuming 100% of crop treated (still conservative) as well as 
assuming a more realistic percent of crop treated based on market 
survey data for existing uses or market projections for proposed uses. 
Adjusting for percent of crop treated is justified because most of 
treated commodities are combined in central locations and broadly 
distributed to the public; none of the clethodim tolerances or uses are 
limited to specific regions in the U.S.; and the primary concern is 
with chronic dietary exposure which minimizes the variance of single 
serving residues. The results of these assessments are summarized below 
in the Safety Determination section and indicate that chronic dietary 
exposures for existing and proposed uses of clethodim are well below 
the reference dose in either case.
    ii. Drinking water. Since clethodim is applied outdoors to growing 
agricultural crops, the potential exists for clethodim or its 
metabolites to leach into groundwater. Drinking water, therefore, 
represents a potential route of exposure for clethodim and should be 
considered in an aggregate exposure assessment.
    Based on available studies used in EPA's assessment of 
environmental risk for clethodim (memo from E. Brinson Conerly dated 
June 26, 1990), clethodim itself was classified as mobile in soil, but 
very non-persistent, representing a minimal groundwater concern. 
Metabolites of clethodim were also classified as mobile, but are 
slightly more persistent (half-lives up to 30-days versus up to 3-days 
for parent). Regarding clethodim metabolites, the Agency concluded that 
the ``potential for groundwater contamination may be somewhat higher 
than for clethodim but would still be expected to be relatively low in 
most cases due to their moderately low persistence''.
    There is no established Maximum Concentration Level for residues of 
clethodim in drinking water under the Safe Drinking Water Act.

[[Page 63945]]

    Based on this information, Valent believes that clethodim appears 
to represent an insignificant risk for exposure through drinking water.
    2. Non-dietary exposure. Clethodim is currently approved for the 
commercial production of agricultural crops including soybeans, cotton, 
sugar beets, onions, and ornamental plants as well as for use on non-
crop areas. The new uses proposed in this notice of filing are all 
agricultural crops. While there is a potential for clethodim to be used 
in non-crop areas (e.g. around parks and rights-of-way) where the 
public does spend some time, the likelihood of significant exposure is 
very small. First, this grass herbicide cannot be sprayed on lawns 
where the public does spend significant amounts of time, but instead 
must be used where there is no crop or around ornamental plants that 
are tolerant to the chemical. The public does not spend significant 
amounts of time in these areas. And second, clethodim is not persistent 
in the environment so the potential for public exposure is short term. 
Therefore, Valent believes that the potential for non-occupational 
exposure to the general public, other than through the diet or drinking 
water, is insignificant.

D. Cumulative Effects

    There is one other pesticide compound registered in the United 
States, sethoxydim, which is structurally related to clethodim and has 
similar effects on animals. Sethoxydim is approved for use on a variety 
of agricultural crops, in non-crop areas, and around the home. This 
chemical should be considered in an aggregate exposure assessment along 
with clethodim. Dietary exposure is expected to represent the major 
route of exposure for sethoxydim as well as for clethodim.
    The reference dose for sethoxydim is 0.09 mg/kg/day based on the 1-
year dog feeding study NOEL and a 100-fold safety factor. This in on 
the same order of magnitude as clethodim, 0.01 mg/kg/day, which is also 
based on a 1-year dog study and a 100-fold safety factor.
    A discussion of the cumulative effects from clethodim and 
sethoxydim exposures is presented below in the Safety Determination 
section.

E. Safety Determination

    1. U.S. population. Using the dietary exposure assessment 
procedures described above for clethodim, chronic dietary exposures 
resulting from existing and proposed uses of clethodim were compared to 
the reference dose (RfD) of clethodim. In Valent's conservative 
assessment (using anticipated residues and assuming 100% treated for 
all crops), exposure for the U.S. population would occupy 13.6% of the 
RfD and non-nursing infants (< 1-year) are most highly exposed with 
total exposure occupying 32.3% of the RfD. Exposure to children 1 to 6 
years old would occupy 27.1% of the RfD. In Valent's realistic analysis 
(using anticipated residues and estimated percent of crop treated for 
all crops), exposure for the U.S. population would occupy only 0.6% of 
the RfD and non-nursing infants are still the highest and would be at 
only 1.6% of the RfD.
    For sethoxydim, recent EPA dietary assessments have been performed 
in conjunction with the extension of several time-limited tolerances. 
In a Final Rule published in the Federal Register of April 11, 1997 (62 
FR 17735) (FRL-5598-7), EPA estimated that exposure to all existing 
tolerances for sethoxydim would occupy 36% of the sethoxydim RfD for 
the U.S. population and 72% of the RfD for the most exposed 
subpopulation of children aged 1- to 6-years. The assumptions used were 
conservative and the final rule stated that ``actual risks using more 
realistic assumptions would likely result in significantly lower risk 
estimates.''
    Since clethodim and sethoxydim have similar toxicological effects 
in mammals, the contributions to the individual reference doses may 
need to be considered in an aggregate exposure assessment. The 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 risks to human health. 
Directly summing the results of the conservative sethoxydim and the 
conservative clethodim contributions to RfD would be approaching 100%. 
However, reliable information is not available to indicate that 
directly summing the percent of RfD for these two chemicals is the most 
appropriate thing to do. Since using realistic assumptions for 
clethodim, including adjustment for percent of crop treated, result in 
large decreases in dietary risk (about 20-fold) Valent expects that the 
sethoxydim risk estimates would also be reduced significantly. 
Therefore, Valent believes that the cumulative chronic dietary risk of 
sethoxydim and clethodim is likely to be well below the 100% level for 
all population subgroups.
    Regarding drinking water exposures, sethoxydim is similar to 
clethodim representing a minimal risk for leaching into groundwater due 
to its rapid degradation in the environment. There is no established 
Maximum Concentration Level for residues of sethoxydim in drinking 
water under the Safe Drinking Water Act.
    Regarding non-occupational exposures, sethoxydim is registered for 
use in non-crop areas and around the home and may have some potential 
for exposure to the general public. However, as discussed for 
clethodim, sethoxydim cannot be applied to grass where public contact 
is expected and sethoxydim is not persistent in the environment. Valent 
therefore expects that non-occupational exposures to the public be 
minimal for sethoxydim.
    In summary, dietary exposure for clethodim and sethoxydim are each 
expected to occupy less than 10% of their RfD's when anticipated 
residue levels and percent of crop treated values are considered. 
Exposures through the drinking water or other non-occupational routes 
are expected by Valent to be minimal. Collectively, Valent believes 
that the aggregate risks associated with the uses of these two 
chemicals is small and demonstrates a reasonable certainty of no harm 
to the public.
    2. Infants and children. As discussed above, dietary exposure for 
clethodim and sethoxydim is greatest for children ages 1-6-years or 
non-nursing infants less than 1-year old. However, using a realistic 
approach to estimating exposures, exposures are expected to be below 
10% of the RfD for each chemical even for infants and children. The 
databases for clethodim and sethoxydim are complete relative to current 
pre- and post-natal toxicity testing requirements including 
developmental toxicity studies in two species and multi-generation 
reproduction studies in rats. Reproduction and developmental effects 
have been found in toxicology studies for clethodim and sethoxydim, but 
the effects were seen at levels that were also maternally toxic. This 
indicates that developing animals are not more sensitive than adults. 
FQPA requires an additional safety factor of up to 10 for chemicals 
which represent special risks to infants or children. Clethodim and 
sethoxydim do not meet the criterion for application of an additional 
safety factor for infants and children. Valent believes that this 
demonstrates a reasonable certainty of no harm to children and infants 
from the proposed uses of clethodim.

F. International Tolerances

    Although some have been proposed, there are no Mexican or Codex 
tolerances or maximum residue limits established for clethodim on 
potatoes, sunflower, or canola commodities. In

[[Page 63946]]

Canada, there are maximum residue limits established for potato tubers 
at 0.5 ppm and canola oil at 0.1 ppm. The use rates proposed for the 
use on tuberous and corm vegetables (crop subgroup 1-C) may exceed the 
0.5 ppm level in tubers so a higher level is necessary. In Canada, 
canola oil is the only canola commodity considered for a residue limit 
since this is the commodity consumed by humans. In the U.S., a 
tolerance is not being proposed for the processed commodity canola oil 
since concentration did not occur in the processing study. 
Consequently, residue in oil up to 0.5 ppm would be allowed in the U.S. 
However, the residue data indicate that residues in oil are not 
expected to exceed 0.1 ppm and Valent does not believe this would 
represent a barrier against exporting U.S.-treated canola oil into 
Canada.


 [FR Doc. 97-31542 Filed 12-2-97; 8:45 am]
BILLING CODE 6560-50-F