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clodinafop-propargyl Pesticide Petition Filing 5/98



[Federal Register: June 5, 1998 (Volume 63, Number 108)]
[Notices]               
[Page 30750-30756]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05jn98-95]

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ENVIRONMENTAL PROTECTION AGENCY

[PF-807; FRL-5791-4]

 
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-807, must 
be received on or before July 6, 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. 119, CM #2, 1921 Jefferson Davis Highway, Arlington, VA.
    Comments and data may also be submitted electronically by following 
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.                         
Beth Edwards (PM 3)...........  Rm. 206, CM #2, 703-    Do.             
                                 305-5400, e-mail:                      
                                 edwards.beth@epamail.                  
                                 epa.gov.                               
------------------------------------------------------------------------

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-807] (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, Food additives, 
Feed additives, Pesticides and pests, Reporting and recordkeeping 
requirements.

    Dated: May 20, 1998.

 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

[[Page 30751]]

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. Novartis Crop Protection, Inc.

PP 7F4924

    EPA has received a pesticide petition (PP 7F4924) from Novartis 
Crop Protection, Inc., P.O. Box 18300, Greensboro, NC 27419-8300 
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 to establish 
tolerances for Clodinafop-propargyl, Propanoic acid, 2-[4-[(5-chloro-3-
fluoro-2-pyridinyl)oxy]phenoxy]-,2-propynyl ester, in or on the raw 
agricultural commodities wheat grain at 0.02 and wheat straw at 0.05 
parts per million (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 
supports granting of the petition. Additional data may be needed before 
EPA rules on the petition.

A. Residue Chemistry

    1. Plant metabolism. The metabolism of CGA-184927 in wheat is 
understood for the purposes of the proposed tolerance. Two studies, one 
with the racemic mixture of the R (+) and S (-) forms and the other 
with the pure R (+) form (CGA-184927 pyridyloxy labeled), gave similar 
results. Metabolism involves hydrolysis of the parent to the resulting 
acid followed by conjugation, arylhydroxylation at the 6 position of 
the pyridyl ring followed by sugar conjugation, and cleavage of the 
pyridinyloxy-phenoxy ether bridge which forms the breakdown products 2-
(4-hydroxyphenoxy) propanoic acid and 2-hydroxy-3-fluoro-5-
chloropyridine.
    2. Analytical method. Novartis has submitted practical analytical 
methods for the determination of CGA-184927 and its major plant 
metabolite CGA-193469 in wheat raw agricultural commodities (RACs). 
CGA-184927 is extracted from crops with acetonitrile, cleaned up by 
solvent partition and solid phase extraction and determined by column 
switching HPLC with ultraviolet detection. CGA-193469 is extracted from 
crops with an acetone-buffer (pH=3) solution, cleaned up by solvent 
partition and solid phase extraction, and determined by HPLC with UV 
detection. The limits of quantitation (LOQ) for the methods are 0.02 
ppm for CGA-184927 in grain and forage, 0.05 ppm for CGA-184927 in 
straw, and 0.05 ppm for CGA-193469 in forage, straw and grain.
    3. Magnitude of residues. Twelve residue trials were conducted from 
1989-1992 in the major spring wheat growing areas of Manitoba, Alberta 
and Saskatchewan, which share compatible crop zones with the major 
spring wheat growing areas of the US (MT, ND, SD, MN). Nine trials were 
conducted in 1989-91 with a tank mix of CGA-184927 and a safener as 
separate EC formulations, and three trials in 1992 were conducted with 
CGA-184927 and the safener as a pre-pack EC formulation. All trials had 
a single post-emergence application of CGA-184927 at a rate of 80 g 
a.i./Ha. At PHIs of 66-97-days, no detectable residues of CGA-184927 or 
its metabolite CGA-193469 were found in mature grain and straw from 
these trials. Separate decline studies (3) on green forage showed no 
detectable residues of CGA-184927 or CGA-193469 beyond the 3-days after 
application (DAA) interval. A freezer storage stability study indicated 
reasonable stability of both analytes for a period of 1-year, with CGA-
184927 showing a decline to 56% in grain and 47% in straw after 2-
years. CGA-193469 remained stable for at least 2-years.

B. Toxicological Profile

    1. Acute toxicity. The acute oral and dermal LD<INF>50</INF> values 
for clodinafop- propargyl are 1829 mg/kg and greater than 2,000 mg/kg 
for rats of both sexes, respectively. Its acute inhalation 
LC<INF>50</INF> in the rat is greater than 2.33 mg/liter, the highest 
attainable concentration. Clodinafop-propargyl is slightly irritating 
to the eyes, minimally irritating to the skin of rabbits, but was found 
to be sensitizing to the skin of the guinea pig. This technical would 
carry the EPA signal word ``Caution''.
    2. Genotoxicty. The mutagenic potential of clodinafop-propargyl was 
investigated in 6 independent studies covering different end points in 
eukaryotes and prokaryotes in vivo and in vitro. These tests included: 
Ames reverse mutation with Salmonella typhimurium and Chinese hamster 
V79 cells; chromosomal aberrations using human lymphocytes and the 
mouse micronucleus test; and DNA repair using rat hepatocytes and human 
fibroblasts. Clodinafop-propargyl was found to be negative in all these 
tests and, therefore, is considered devoid of any genotoxic potential 
at the levels of specific genes, chromosomes or DNA primary structure.
    3. Reproductive and developmental toxicity. Dietary administration 
of clodinafop-propargyl over 2-generations at levels as high as 1,000 
ppm did not affect mating performance, fertility or litter sizes. The 
physiological developmental and the survival of the pups during the 
last week of the lactation period were slightly reduced at levels equal 
to or greater than 500 ppm during the first generation only. Target 
organs were liver (adults) and kidney (adults and pups). The treatment 
had no effect on reproductive organs. The developmental and 
reproductive NOEL was 50 ppm, corresponding to a mean daily intake of 
3.3 milligrams/kilogram (mg/kg) clodinafop-propargyl.
    In a developmental toxicity study in rats, the highest dose level 
of 160 mg/kg resulted in reduced body weight gain of the dams and signs 
of retarded fetal body weight and incomplete ossification of vertebrae 
and sternebrae. No teratogenic activity of the test article was 
detected. The NOEL for dams and fetuses was 40 mg/kg/day.
    In a developmental toxicity study in rabbits, mortality was 
observed in dams at dose levels of 125 and 175 mg/kg. No teratogenic or 
fetotoxic effects were noted. The maternal NOEL was 25 mg/kg/day and 
the fetal NOEL was 175 mg/kg/day.
    4. Subchronic toxicity. A 90-day feeding study in rats at 1,000 ppm 
resulted in reduced body weight gain, increased liver weights, 
hematological changes, and increased serum activities of the alkaline 
phosphatase. Target organs were liver (increased weight), thymus 
(atrophy) and spleen (reduced weight). The changes were reversible 
during 4-weeks of recovery. The NOEL was 15 ppm (0.92 mg/kg in males 
and 0.94 mg/kg in females).
    In a 90-day feeding study in mice, 400 ppm resulted in reduced 
activity, one death, markedly increased activities of 
aminotransferases, alkaline phosphatase, and albumin concentration, 
increased liver weights, hepatocellular hypertrophy, and single cell 
necroses in all mice. Other findings included intrahepatic bile duct 
proliferation, Kupffer cell hyperplasia and higher incidence of 
inflammatory cell infiltration. These findings were considered to be 
secondary to the hepatocyte necrosis. The NOEL of 6 ppm was equivalent 
to a daily dose of 0.9 mg/kg in males and 1.05 mg/kg in females.
    In a 90-day study in beagle dogs, levels of 500 and 1,000 ppm fed 
over 1-weeks clearly exceeded a maximum tolerated dose and led to 
mortality and severe toxicity. Effects at 50 and 200 ppm were limited 
to dermatitis and

[[Page 30752]]

clinical chemistry changes, which were generally mild and transient. 
The NOEL of 10 ppm was equivalent to a mean daily intake of 0.36 mg/kg 
in males and females.
    5. Chronic toxicity. In a 12-month feeding study in dogs, 500 ppm 
resulted in transient dermatitis and reduced body weight gain. Two 
females were more severely affected and showed inappetence, body weight 
loss, tremors and severe dermatitis, and necessitated an interruption 
of the treatment in order to avoid mortality. Histopathology revealed 
slight hepatocellular hypertrophy in one male and one female. The NOEL 
of 100 ppm was equivalent to a mean daily intake of 3.38 mg/kg in males 
and 3.37 mg/kg in female.
    Lifetime dietary administration of clodinafop-propargyl to mice 
resulted in reduced body weights and reduced survival in males treated 
at 250 ppm. Severe hepatotoxicity was noted at 100 and 250 ppm in both 
sexes. Based on markedly increased liver weights, enhanced serum 
activities of hepatic enzymes and hepatocellular necroses, dietary 
levels of 100 ppm and 250 ppm clearly exceeded maximum tolerated doses 
in males and females, respectively. The increased incidence of benign 
liver tumors that occurred in males treated at 250 ppm was, therefore, 
considered a toxicologically irrelevant response as the livers of these 
animals were damaged significantly and this finding was not 
interpretable. The test substance was severely hepatotoxic at 100 and 
250 ppm, with males being more sensitive than females. Based on 
markedly increased liver weights, enhanced serum activities of hepatic 
enzymes, and hepatocellular necroses, dietary levels of 100 ppm and 250 
ppm clearly exceeded maximum tolerated doses in males and females, 
respectively. The incidence of hepatocellular carcinoma, in these 
clearly compromised mice, remained within the historical control range, 
although the incidence was slightly increased in comparison to the 
concomitant controls. Tumor incidences in females were generally low 
and well within the range of the historical controls. The NOEL of 10 
ppm was equivalent to a mean daily dose of 1.10 mg/kg in males and 1.25 
mg/kg in females.
    Dietary treatment of rats with concentrations over 2-years resulted 
in initial inappetence in males and reduced body weight development in 
both sexes treated at 750 ppm. The main target organ of toxicity was 
the liver. Changes in plasma protein and lipid levels, strongly 
enhanced serum activities of liver enzymes, increased liver weights, 
and severe hepatocellular necroses were observed at dietary doses of 
300 and 750 ppm in males and at 750 ppm in females, giving evidence 
that these dose levels exceeded a maximum tolerated dose (MTD). Top 
dose group males showed higher incidences of prostate adenoma, while 
prostate hyperplasia was reduced. The total incidence of proliferative 
changes in the prostate remained unchanged. Females treated at the same 
high dose had higher incidences of ovary tubular adenoma. Both tumors 
also occur spontaneously in the rat strain used. Their slightly 
enhanced incidences are likely a consequence of the severe disturbance 
of the general physiological balance due to excessive liver toxicity. 
There was no progression to a malignant phenotype and the tumors had no 
influence on survival. In rats, feeding a dose of 750 ppm to males 
showed higher incidences of prostate adenoma, while prostate 
hyperplasia was reduced. The total number of tumor-bearing animals 
showed no dose-related trends. The NOEL of 10 ppm was equivalent to a 
mean daily dose of 0.32 mg/kg in males and 0.37 mg/kg in females.
    6. Animal metabolism. In rats, clodinafop-propargyl was rapidly 
absorbed through the gastrointestinal tract. Absorption through the 
skin of rats is considerably slower with 15% of a dermally applied dose 
being absorbed within 8-hours. Single doses were excreted more rapidly 
by female rats than by males. Most likely due to enzyme induction, 
differences were much less pronounced after repeated treatment. Both 
sexes excreted clodinafop-propargyl with urine and feces mainly in the 
form of its propionic acid derivative, CGA-193469. Simultaneous 
administration of the safener, cloquintocet-mexyl, did not alter the 
rate of excretion of clodinafop-propargyl or its metabolite pattern.
    7. Metabolite toxicology. Clodinafop-propargyl acts as a typical 
peroxisome proliferator in the rodent liver which is most likely 
induced by its propionic acid derivative metabolite, CGA-193469. Like 
other known well-characterized substances with this property, CGA-
193469 caused peroxisome proliferation in vitro in hepatocytes of the 
mouse and rat, but not of the Guinea pig, marmoset, or human. There is 
ample scientific evidence that exposure to peroxisome proliferators 
represents no risk of tumor development in man. Clodinafop-propargyl 
is, therefore, not considered to be a carcinogen of relevance to 
humans.
    8. Endocrine disruption. No special studies investigating potential 
estrogenic or endocrine effects of clodinafop-propargyl have been 
conducted. However, the standard battery of required studies has been 
completed. These studies include an evaluation of the potential effects 
on reproduction and development and an evaluation of the pathology of 
the endocrine organs following repeated or long-term exposure. Although 
prostate adenomas and ovarian adenomas were observed to be 
statistically increased in rats at the highest feeding level with 
clodinafop-propargyl, this feeding level clearly exceeded the MTD and 
the livers in these rats were severely compromised. Therefore, these 
findings are considered irrelevant.

C. Aggregate Exposure

    1. Dietary exposure. For purposes of assessing the potential 
exposure under the proposed tolerances for clodinafop-propargyl, 
Novartis has estimated aggregate exposure based on the theoretical 
maximum residue contribution (TMRC) from the residues of the active 
ingredient, clodinafop-propargyl, or metabolites thereof. Residues are 
below the detection limit in wheat grains and other wheat products, 
including green wheat used for forage. Tolerances in wheat and wheat 
products are proposed at the detection limit of 0.02 ppm (LOQ) for the 
parent active ingredient in wheat grain. Although wheat commodities may 
be fed to poultry or cattle and it is common practice in some areas to 
graze cattle on green wheat, tolerances in meat or milk are not 
necessary because forage commodities do not contain detectable amounts 
of the parent clodinafop-propargyl or its metabolites.
    i. Chronic. The RfD of 0.0032 mg/ kg/day is derived from the male 
rat NOEL of 0.32 mg/ kg/ day. Based on the assumption that 100% of all 
wheat used for human consumption would contain residues of clodinafop-
propargyl and anticipated residues would be at the level of \1/2\ the 
LOQ, the potential dietary exposure was calculated using the TAS (TAS 
Exposure Analysis, Technical Assessment Systems Inc., Washington, DC.) 
exposure program based on the food survey from the year of 1977/1978. 
Calculations were made for anticipated residues using \1/2\ the LOQ or 
0.01 ppm. The proposed tolerance (0.02 ppm) was set at the lowest limit 
of detection for the active ingredient in wheat commodities (grain) 
because, with the available methodology, there are no detectable 
residues of clodinafop-propargyl in wheat or wheat products. Residues 
in milk, meat and eggs due to the feeding of wheat grain, green wheat 
or other

[[Page 30753]]

feed commodities will not occur and tolerances for milk, meat and eggs 
are therefore not required. Calculated on the basis of the assumptions 
above, the chronic dietary exposure of the U.S. population to 
clodinafop-propargyl would correspond to 0.000014 mg/kg/day or 0.47% of 
its RfD. The margin of exposure (MOE) against the NOEL in the most 
sensitive species is 22,857-fold.
    Using the same conservative exposure assumptions, the percentage of 
the RfD that will be utilized is 0.14% for nursing infants less than 1-
year old, 0.34% for non-nursing infants, 1.05% for children 1-6 years 
old and 0.77% for children 7-12 years old. It is concluded that there 
is a reasonable certainty that no harm will result to infants and 
children from exposure to residues of clodinafop-propargyl.
    ii. Acute. Using the same computer software package used for the 
calculation of chronic dietary exposure, the acute dietary exposure was 
calculated for the general population and several sub-populations 
including children and women of child bearing age. The USDA Food 
Consumption Survey from 1989-1992 was used, however, instead of the 
1977/78 survey used for the chronic assessment. Margins of exposure 
were calculated against the NOEL of 1 mg/kg found in a 90-day dietary 
toxicity study in rats, which is the lowest NOEL observed in a short 
term or reproductive toxicity study. NOEL from reproductive or 
developmental toxicity studies were significantly higher and there was 
no evidence that clodinafop-propargyl has any potency to affect these 
endpoints.
    The exposure model predicted that 99.9% of the general population 
will be exposed to less than 0.000105 mg/kg of clodinafop-propargyl per 
day, which corresponds to a MOE of almost 9,529 when compared to the 
NOEL of 1 mg/kg. Children 1-6 years constitute the sub-population with 
the highest predicted exposure. Predicted acute exposure for this 
subgroup is less than 0.000136 mg/kg/day, corresponding to a MOE of at 
least 7,362 for 99.9% of the individuals.
    2. Drinking water. Other potential sources of exposure of the 
general population to residues of pesticides are residues in drinking 
water. Although clodinafop-propargyl has a slight to medium leaching 
potential, the risk of the parent compound to leach to deeper soil 
layers is negligible under practical conditions in view of the rapid 
degradation of the product and its low application rate. According to 
laboratory and field studies there is no risk of ground water 
contamination with clodinafop-propargyl or its metabolites. Thus, 
aggregate risk of exposure to clodinafop-propargyl does not include 
drinking water. Clodinafop-propargyl is not intended for uses other 
than the agricultural use on wheat. Thus, there is no potential for 
non-occupational exposure.
    The Maximum Contaminant Level Goal (MCLG) calculated for 
clodinafop-propargyl according to EPA's procedure leads to an exposure 
value substantially above levels that are likely to be found in the 
environment under proposed conditions of use.
    MCLG = RfD x 20% x 70 kg/2 L
    MCLG = 0.0032 mg/kg x 0.2 x 70 kg/2 L
    MCLG = 0.0448 ppm = 44.8 ppb.
    3. Non-dietary exposure. Exposure to clodinafop-propargyl 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 10-days per year by ground boom application to 
a maximum of 300 acres per day by the grower, 450 acres per day by the 
commercial ground boom applicator and 741 acres per day by the aerial 
applicator at a maximum use rate of 28 grams active ingredient per 
acre. For purposes of this assessment, it was assumed that an 
applicator would be wearing a long-sleeved shirt and long pants and the 
mixer/loader would, in addition, wear gloves. These assumptions were 
selected from PHED. Daily doses were calculated for a 70 kg person 
assuming 100% dermal penetration. The results indicate that large 
margins of safety exist for the proposed use of clodinafop-propargyl. 
Based upon the use pattern for clodinafop, the NOEL (50 mg/kg/day) from 
the 28-day rat dermal study is appropriate for comparison to mixer/
loader-applicator exposure. The chronic NOEL of 0.32 mg/kg/day from the 
2-year feeding study in rats is used to examine longer term exposures.
    For short-term exposure, MOEs for clodinafop ranged from 2.9E+03 
for commercial open mixer-loader to 3.1E+04 for commercial groundboom 
enclosed-cab applicator. For chronic exposure, MOEs ranged from 6.9E+02 
for commercial open mixer-loader to 7.4E+03 for commercial groundboom 
enclosed-cab applicator. Aerial application of clodinafop results in 
short-term MOEs of 1.8E+03 for the mixer-loader and 2.0E+03 for pilots. 
Chronic MOEs are 4.2E+02 for the mixer-loader and 4.7E+02 for the 
pilot.
    In reality, the proposed label will require more restrictive 
personal protective equipment for applicators and other handlers, 
resulting in additional margins of safety.

D. Cumulative Effects

    A cumulative exposure assessment for effects of clodinafop-
propargyl and other substances with the same mechanism of action is not 
appropriate because there is ample evidence to indicate that humans are 
not sensitive to the effects of clodinafop-propargyl and other 
peroxisome proliferators. Thus, the calculations outlined below were 
done for clodinafop-propargyl alone.

E. Safety Determination

    1. U.S. population. Using the same conservative exposure 
assumptions described above, based on the completeness and reliability 
of the toxicity data, Novartis calculated that the aggregate risk for 
clodinafop-propargyl for chronic dietary exposure of the U.S. 
population would correspond to 0.000014 mg/kg/day or 0.47% of its RfD. 
The margin of exposure (MOE) against the NOEL in the most sensitive 
species is 22,857-fold. 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. Therefore, it is concluded that 
there is a reasonable certainty that no harm will result from aggregate 
exposure to residues of clodinafop-propargyl.
    2. Infants and children. In assessing the potential for additional 
sensitivity of infants and children to residues of clodinafop-
propargyl, data from developmental toxicity studies in the rat and 
rabbit and a 2-generation reproduction study in the rat have been 
considered. The developmental toxicity studies are designed to evaluate 
adverse effects on the developing organism resulting from chemical 
exposure during prenatal development to one or both parents. 
Reproduction studies provide information relating to effects from 
exposure to a chemical on the reproductive capability of mating animals 
and data on systemic toxicity.
    Retarded fetal body weight and incomplete ossification of vertebrae 
and sternebrae were observed at a maternally toxic dose of 160 mg/kg/
day in rats; however, no teratogenic activity of the test article was 
detected. The NOEL for dams and fetuses was 40 mg/kg/day. Although 
mortality was observed in rabbit dams at dose levels of 125 and 175 mg/
kg, no teratogenic or fetotoxic effects were noted. The maternal NOEL 
was 25 mg/kg/day and the fetal NOEL was 175 mg/kg/day.
    Clodinafop-propargyl fed over 2-generations to rats at levels as 
high as 1,000 ppm did not affect mating

[[Page 30754]]

performance, fertility, or litter sizes. Physiological developmental 
and the survival of the pups during the last week of the lactation 
period were slightly reduced at levels equal to or greater than 500 ppm 
during the first generation only. Target organs were liver (adults) and 
kidney (adults and pups). The developmental and reproductive NOEL was 
50 ppm, corresponding to a mean daily intake of 3.3 mg/kg clodinafop-
propargyl.
    Section 408 FFDCA provides that EPA may apply an additional safety 
factor for infants and children in the case of threshold effects to 
account for pre- and post-natal toxicity and the completeness of the 
database. Base on the current toxicological data requirements, the 
database relative to pre- and post-natal effects for children is 
complete. Further, for clodinafop-propargyl, the NOEL of 0.32 mg/kg/day 
from the combined chronic/oncogenicity rat study, which was used to 
calculate the RfD, is already lower than the NOEL's of 40 and 25 mg/kg/
day for the rat and rabbit developmental toxicity studies, 
respectively. Further, the developmental and reproductive NOEL of 3.3 
mg/kg/day from the clodinafop-propargyl reproduction study is 10- times 
greater than the NOEL for the combined chronic/oncogenicity rat study. 
These data would indicate there is no additional sensitivity of infants 
and children to clodinafop-propargyl. Therefore, it is concluded that 
an additional uncertainty factor is not warranted to protect the health 
of infants and children from the use of clodinafop-propargyl.
    Using the conservative exposure assumptions described above, it is 
concluded that the percentage of the RfD that will be utilized by 
aggregate exposure to residues of clodinafop-propargyl for the proposed 
use on wheat is 0.14% for nursing infants less than 1-year old, 0.34% 
for non-nursing infants, 1.05% for children 1-6 years old and 0.77% for 
children 7-12 years old. Therefore, based on the completeness and 
reliability of the toxicity data and the conservative nature of the 
exposure assessment, it is concluded that there is a reasonable 
certainty that no harm will result to infants and children from 
exposure to residues of clodinafop-propargyl.

F. International Tolerances

    There are no Codex Alimentarius Commission (CODEX) maximum residue 
levels (MRLs) established for residues of clodinafop-propargyl in or on 
raw agricultural commodities. (Joanne Miller)


[FR Doc. 98-15014 Filed 6-4-98; 8:45 am]
BILLING CODE 6560-50-F