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Rimsulfuron - Pesticide Petition Filing 2/98

[Federal Register: February 20, 1998 (Volume 63, Number 34)]
[Notices]
[Page 8635-8644]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr20fe98-60]

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ENVIRONMENTAL PROTECTION AGENCY

[PF-791; FRL-5768-9]

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 agricultural commodities.

DATES: Comments, identified by the docket control number PF-791, must
be received on or before March 23, 1998.

ADDRESSES: By mail submit written comments to: Information and Records
Integrity Branch, Public Information and Services Divison (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. 119 at the
address given above, from 8:30 a.m. to 4 p.m., Monday through Friday,
excluding legal holidays.

FOR FURTHER INFORMATION CONTACT: By mail: James A. Tompkins, Product
Manager (PM) 25, Registration Division, (7505C), Office of Pesticide
Programs, Environmental Protection Agency, 401 M St., SW., Washington,
DC 20460. Office location and telephone number: Rm. 239, 1921 Jefferson
Davis Hwy., Arlington, VA., (703) 305-5697; e-mail:
Tompkins.jim@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 raw
agricultural 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 grantinig of the petition. Additional data may be needed
before EPA rules on the petition.
    The official record for this notice, as well as the public version,
has been established for this notice of filing under docket control
number PF-791 (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 5.1/6.1 file format or
ASCII file format. All comments and data in electronic form must be
identified by the docket control number (insert docket number) and
appropriate petition number. Electronic comments on this notice may be
filed online at many Federal Depository Libraries.
    Authority: 21 U.S.C. 346a.

List of Subjects

    Environmental protection, Agricultural commodities, Food additives,
Feed additives, Pesticides and

[[Page 8636]]

pests, Reporting and recordkeeping requirements.

    Dated: February 12, 1998.

Donald R. Stubbs,
Acting Director, Registration Division, Office of Pesticide Programs.

Summaries of Petitions

    Below summaries of the pesticide petitions are printed. The
summaries of the petitions were prepared by the petitioners. 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.

2. E.I. du Pont de Nemours & Company

PP 6F4706

    EPA has received a pesticide petition (PP 6F4706)from E.I. du Pont
de Nemours & Company, Barley Mill Plaza, P.O. Box 80038, Willimington,
DE 19880-0038. 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 rimsulfuron: N-((4,6-
dimethoxypyrimidin-2-yl) aminocarbonyl) -3- (ethylsulfonyl) -2-
pyridinesulfonamide in or on the raw agricultural commodity tomato
fruit at 0.10 parts per million. 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. With the initial establishment of rimsulfuron
tolerances in field corn and potatoes, the EPA determined that the
nature of plant residues was adequately understood for the purposes
establishing those tolerances. A metabolism study on tomatoes was

conducted at the following use rates:

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Tomatoes grown in field.....              72 g AI/hectare (approx. 1 oz. AI/acre, max. prop. use rate).
Tomatoes grown in greenhouse             172, 350, & ca. 700 g AI/hectare (2.5, 5, and 10 oz. AI/acre
                                                or up to 10 times the prop. max. use rate).
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[[Page 8639]]

    No residues of rimsulfuron or any metabolite were detected in any
tomato fruit, immature or mature. Detection limits for the study were
0.004 ppm for the field-grown samples and 0.013 ppm for the greenhouse-
grown samples. This study conclusively shows that application of
rimsulfuron to tomatoes, when used in accordance with the proposed
label directions, will not result in detectable residue of rimsulfuron
or its metabolites in tomato fruit. Therefore, the nature of
rimsulfuron residues (i.e., their absence) has been established for
tomato fruit, the only raw agricultural commodity established for
tomatoes.
    2. Analytical method. Adequate analytical methodology, high-
pressure liquid chromatography with Uv detection, is available for
enforcement purposes. The method is "Analytical Method for the
Quantitiation of DPX-E9636 (rimsulfuron) in Various Crop Matrices and
Their Processed Fractions", DuPont Report No. AMR 3424-95, EPA MRID
No. 43979002. The method involves liquid chromatography utilizing
eluent and column switching with UV/VIS detection at 254 nm. The limit
of quantitation for rimsulfuron in tomatoes is 0.05 ppm. EPA offers
enforcement methodology to anyone interested in pesticide enforcement
when requested by mail from: Calvin Furlow, Public Response and Program
Resources Branch, Field Operations Division (7506C), Office of
Pesticide Programs, Environmental Protection Agency, 401 M St., SW.,
Washington, DC 20460. Office location and telephone number: Rm. 1130A,
CM#2, 1921 Jefferson Davis Hwy., Arlington, VA 22202.
    3. Magnitude of residues. --i. Plant residues. Magnitude of
residues of rimsulfuron in tomato fruit were determined following
application of rimsulfuron at the proposed maximum annual use rate of
1.0 oz ai/acre (1 x ), and at twice that rate (2 x ). An additional
test was conducted at an exaggerated rate of 5.0 oz ai/acre (5 x ) in
an attempt to generate quantifiable residues in tomato fruit (RAC) for
a processing study.
    Seventeen tests, each containing one control and two treatment
plots, were established in California, Florida, Indiana, Maryland, and
Pennsylvania. Row-crop tomato samples were collected approximately 45
days following the final application; staked tomatoes were collected
immediately following the final application. Tomato samples were
analyzed using the procedures described in DuPont Method No. AMR 3424-
95, Analytical Method for the Quantitation of DPX-E9636 in Various Crop
Matrices and Their Processed Fractions. The overall mean percent
recovery of 52 control tomato samples fortified at either 0.05 or 0.10
ppm was 86%, with a relative standard deviation of 4%. Results of
freezer storage stability study indicate that rimsulfuron is stable up
to 6 months in tomatoes stored at -20C +/- 5C.
    No quantifiable residues (<0.05 ppm) of rimsulfuron were found in
any of the tomato samples treated at 1.0, 2.0, and 5.0 oz ai/acre. A
processing study was not necessary since all 1 x  and 5 x  samples did
not have rimsulfuron present with a limit of quantitation of 0.05 ppm.
    Data generated from this study support the use of rimsulfuron on
tomatoes at a maximum seasonal use rate of 1.0 oz ai/acre with a
minimum preharvest interval of 45 days. Study results also support the
petition for a 0.10 ppm tolerance of rimsulfuron on tomatoes.
    ii. Animal residues. EPA determined, upon granting field corn and
potato tolerances, that there is no reasonable expectation of residues
occurring in meat, milk, poultry, or eggs from these tolerances. Tomato
fruit and its processed commodities (i.e., tomato paste and puree) are
not considered by the EPA to be animal feed items. Further, no residues
would be available to enter animal feed based on results from the
tomato metabolism study and magnitude or residue study discussed above.
Therefore, there remains a reasonable expectation that no residue of
rimsulfuron will occur in meat, milk, poultry, or eggs from all
rimsulfuron tolerances, current (field corn and potatoes) and proposed
(tomatoes).

B. Toxicological Profile

    1. Acute toxicity. Technical rimsulfuron has been placed in acute
toxicology category III based on overall results from several studies.
This compound was placed in toxicology category III for acute dermal
toxicity (LD50 > 2,000 mg/kg; rabbits) and eye irritation
(effects reversible within 72 hours; rabbits). Acute oral toxicity
(LD50 > 5,000 mg/kg; rats), acute inhalation toxicity
(LC50 > 5.4 mg/L, rats) and skin irritation (no observed
irritation; rabbits) results were assigned toxicology category IV.
Technical rimsulfuron is not a dermal sensitizer.
    2. Genotoxicty. Technical rimsulfuron was negative for genotoxicity
in a battery of in vitro and in vivo tests. These tests included the
following: mutagenicity in bacterial (Ames test) and mammalian (CHO/
HGPRT assay) cells; in vitro cytogenetics (chromosomal aberration in
human lymphocytes); in vivo cytogenetics (bone marrow micronucleus
assay in mice); and unscheduled DNA synthesis in rat primary
hepatocytes.
    3. Reproductive and developmental toxicity. A two-generation
reproduction study was conducted in rats with dietary technical
rimsulfuron concentrations of 0, 50, 3,000 or 15,000 ppm. The study was
negative for reproductive toxicity and there was no indication that
offspring were more susceptible to rimsulfuron administration than
parents. The NOEL was 3,000 ppm (or 165 to 264 mg/kg/day for P1 and F1
males and females and their offspring). This was based on the following
effects at 15,000 ppm (830 to 1,316 mg/kg/day): lower food consumption
and/or food efficiency in P1 males and females and F1 females;
decreased mean body weights and/or body weight gain by P1 and F1 males
and females; lower mean body weights and increased incidence of small
body size for F2 pups during lactation.
    A developmental study was conducted in rats administered technical
rimsulfuron by gavage at 0, 200, 700, 2,000 or 6,000 mg/kg/day. There
were no systemic or developmental effects observed up to and including
the highest dose tested. The NOEL was therefore > 6,000 mg/kg/day.
    A developmental study was conducted in rabbits administered
technical rimsulfuron by gavage at 0, 25, 170, 500 or 1,500 mg/kg/day.
The NOELs for maternal and offspring toxicity were 170 and 500 mg/kg/
day, respectively. The maternal NOEL was based on reduced body weight
and mortality at higher doses. These maternal effects precluded any
evaluation of adverse effects in fetuses at 1,500 mg/kg/day; however,
there were no systemic or developmental effects observed among fetuses
at 500 mg/kg/day and below.
    4. Subchronic toxicity. A 90-day study in mice was conducted at
dietary concentrations of 0, 50, 375, 1,500 or 7,500 ppm. The NOELs
were 375 ppm (56.0 mg/kg/day) for male mice and 7,500 ppm (1,575 mg/kg/
day) for female mice. The NOEL for males was based on slight reductions
in mean body weight gain and food efficiency at 1,500 ppm (228 mg/kg/
day).
    Technical rimsulfuron was administered in the diets of rats at 0,
50, 1,500, 7,500 or 20,000 ppm for 90 days. The NOEL was 1,500 ppm (102
and 120 mg/kg/day for males and females, respectively) based on reduced
mean body weights and body weight gains and increased relative liver
weights at

[[Page 8640]]

7,500 ppm (495 and 615 mg/kg/day for males and females, respectively).
    Dogs were administered technical rimsulfuron in their diets at 0,
250, 5,000 or 20,000 ppm for 90 days. The NOEL was 250 ppm (9.63 and
10.6 mg/kg/day for males and females, respectively). This was based on
slight increases in liver and/or kidney weights, increased urine volume
and decreased urine osmolarity at 5,000 ppm (193 and 189 mg/kg/day for
males and females, respectively).
    5. Chronic toxicity. An 18-month mouse study was conducted with
dietary concentrations of 0, 25, 250, 2,500 or 7,500 ppm technical
rimsulfuron. This product was not oncogenic in mice. The systemic NOEL
was 2,500 ppm (351 and 488 mg/kg/day for males and females,
respectively) based on decreased mean body weights in both sexes and
increased incidence of spontaneous, age-related artery and tunica
degeneration in the testes for this mouse strain at the highest dose
tested, 7,500 ppm (1,127 and 1,505 mg/kg/day for males and females,
respectively). The latter was observed in the absence of any effect on
spermatogenesis. An increased incidence of dilation and cysts in the
glandular stomach of males was also observed at 7,500 ppm.
    A 2-year chronic toxicity/oncogenicity study was conducted in rats
fed diets that contained 0, 25, 300, 3,000 or 10,000 ppm technical
rimsulfuron. This product was not oncogenic in rats. The systemic NOELs
were 300 ppm (11.8 mg/kg/day) for males and 3,000 ppm (163 mg/kg/day)
for females. The NOELs were defined by decreased body weight gain and
increased relative liver weights at 3,000 ppm (121 mg/kg/day) and
10,000 ppm (569 mg/kg/day) for males and females, respectively.
    Technical rimsulfuron was administered for one year to dogs at
dietary concentrations of 0, 50, 2,500 or 10,000 ppm. The NOELs were 50
ppm (1.6 mg/kg/day) for males and 2,500 ppm (86.5 mg/kg/day) for
females. The NOEL for males was based on the following effects observed
at 2,500 ppm (81.8 mg/kg/day): increased absolute liver and kidney
weights; and increased incidence of seminiferous tubule degeneration
and increased numbers of spermatid giant cells present in the
epididymides. The NOEL for females was based on the following effects
observed at 10,000 ppm (358.5 mg/kg/day): decreased body weight and
body weight gain; increased serum cholesterol levels and alkaline
phosphatase activity, increased absolute liver weight and increased
relative liver and kidney weights.
    6. Animal metabolism. The metabolism of rimsulfuron in animals
(rat, goat and hen) is adequately understood and is similar among the
species evaluated. Rimsulfuron was rapidly eliminated via urinary and
fecal excretion in the rat. Approximately 60 to 70% of the administered
dose to rats was excreted within 24 hours. There were no volatile
metabolites detected and unmetabolised rimsulfuron was the major
component in the urine (42 - 55%) and feces (5 - 16%). The major
metabolic pathway in rats involved a contraction of the sulfonylurea
bridge followed by dealkylation, hydroxylation and/or conjugation
reactions. Cleavage of the sulfonylurea bridge was observed; however,
it was considered to be a minor pathway. Elimination of administered
rimsulfuron was similarly rapid for the goat and hen. Tissue residue
levels were generally less than 0.3% of the administered dose for the
rat, goat and hen. There was no evidence of accumulation of rimsulfuron
or its metabolites in tissues of any of the species or in milk and
eggs.
    7. Metabolite toxicology. Common metabolic pathways for rimsulfuron
were demonstrated in the rat, goat and hen as well as plants (corn,
tomatoes and potatoes). When evaluated for acute toxicity and
mutagenicity, two of the major metabolites, i.e., one resulting from
contraction of the sulfonylurea bridge and one from the cleavage of
this bridge, were found to be of low toxicity and were negative in the
Ames test. The existing metabolism studies indicate that the
metabolites formed are unlikely to accumulate in humans or in animals
that may be exposed to these residues in the diet. The fact that no
quantifiable residues were found in treated crops further indicates
that exposures to and accumulation of metabolites are unlikely. Because
of the above, toxicology studies on metabolites were not required.

C. Aggregate Exposure

    1. Dietary exposure -- Residue of concern. When tolerances were
established on field corn and potatoes, EPA determined that the residue
of concern was rimsulfuron. The metabolism study conducted on tomatoes
(see Plant Metabolism Section) showed no residues of rimsulfuron are
present in the tomato fruit. Therefore, the residue of concern
continues to be rimsulfuron.
    2. Food. For the general U.S. population, acute dietary exposure
assessments were not considered relevant for rimsulfuron for the
following reasons: rimsulfuron presents very low acute toxicity based
on animal testing; and no detectable residues have been demonstrated in
edible portions of treated crops.
    The Agency has conducted chronic dietary exposure assessments for
rimsulfuron and the results are summarized below. The Reference Dose
(RfD) is based on a NOEL of 1.6 mg/kg/day established in the 1-year
feeding study with dogs and combines an uncertainty factor of 100. EPA
calculated the RfD to be 0.016 mg/kg/day. The theoretical maximum
residue contribution (TMRC) for these tolerances for the overall U.S.
population is 1.47  x  10-4 mg/kg/day or 0.92% of the RfD
based on current (field corn and potatoes) tolerances and would be 2.21
 x  10-4, or 1.4% of the RfD when the proposed tolerance on
tomatoes is included.
    For infants and children, the TMRC for the most exposed subgroup,
children (1 to 6 years old), is 2.37  x  10-4 mg/kg/day,
respectively, or 1.95% of the RfD based on current (field corn and
potatoes) tolerances and would be 4.37  x  10-4 mg/kg/day,
or 2.73% of the RfD, when the proposed tomato tolerance is included. As
with calculations for the general US population, these values assume
the residues are at the established tolerance level and that 100
percent of the crop is treated.
    3. Drinking water. Another potential dietary source of exposure of
the general population to residues of pesticides is residues in
drinking water. There have been no field studies or monitoring programs
conducted to assess rimsulfuron residues in groundwater or drinking
water. Several factors indicate very low potential that rimsulfuron
will be present in raw or finished drinking water: low use rate (1 oz
a.i./acre), rapid hydrolysis (half-life < 7 days), short half-lives
under field conditions (7-18 days), absence of leaching in field soil
dissipation studies. Water solubility for rimsulfuron is as follows:

[[Page 8641]]

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Unbuffered Water:.                                                              < 10 ppm
Buffers:..........  pH 5                                                         135 ppm
  ................  pH 7                                                       7,300 ppm
  ................  pH 9   5,560 ppm (rapidly decomposes at pH 9); Koc is less than 100.
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    Computer modeling, taking into account use rate, physical
properties, and degradation rates, predicts low probability of
rimsulfuron being present in ground- or drinking water. Given that only
2.73% of the RfD is attained by the TMRC for the population sub-group
with the highest theoretical dietary exposure (children 1-6 years old;
see above), there is ample allowance for safe exposure to rimsulfuron
via drinking water.
    4. Non-dietary exposure. Rimsulfuron is not registered for any use
which could result in non-occupational, or non-dietary exposure to the
general population.

D. Cumulative Effects

    Rimsulfuron belongs to the sulfonylurea class of crop protection
chemicals. Other structurally similar compounds in this class are
registered herbicides. However, the herbicidal activity of
sulfonylureas is due to the inhibition of acetolactate synthase (ALS),
an enzyme found only in plants. This enzyme is part of the biosynthesis
pathway leading to the formation of branched chain amino acids. Animals
lack ALS and this biosynthetic pathway. This lack of ALS contributes to
the relatively low toxicity of sulfonylurea herbicides in animals.
There is no reliable information that would indicate or suggest that
rimsulfuron has any toxic effects on mammals that would be cumulative
with those of any other chemical.

E. Safety Determination

    1. U.S. population. Based on the completeness and reliability of
the toxicology database and using the conservative assumptions
presented earlier, EPA has established an RfD of 0.016 mg/kg/day. This
was based on the NOEL for the 1-year dog study of 1.6 mg/kg/day and
employed a 100-fold uncertainty factor. It has been concluded that the
aggregate exposure for existing crops (corn and potatoes) would utilize
0.92% of the RfD and that the addition of tomatoes would increase
utilization to 1.4% of the RfD. Generally, exposures below 100% of the
RfD are of no concern because it represents the level at or below which
daily aggregate dietary exposure over a lifetime will not pose
appreciable risk to human health. Thus, there is reasonable certainty
that no harm will result from aggregate exposures to rimsulfuron
residues.
    2. Infants and children. In assessing the potential for additional
sensitivity of infants and children to residues of rimsulfuron, data
from the previously discussed developmental and multigeneration
reproductive toxicity studies were considered.
    Developmental studies are designed to evaluate adverse effects on
the developing organism resulting from pesticide exposure during pre-
natal development. Reproduction studies provide information relating to
reproductive and other effects on adults and offspring from pre-natal
and post-natal exposures to the pesticide. The studies with rimsulfuron
demonstrated no evidence of developmental toxicity at exposures below
those causing maternal toxicity. This indicates that developing animals
are not more sensitive to the effects of rimsulfuron administration
than adults.
    FFDCA section 408 provides that EPA may apply an additional
uncertainty 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. Based on current toxicological data
requirements, the database for rimsulfuron relative to pre- and post-
natal effects for children is complete. In addition, the NOEL of 1.6
mg/kg/day in the 1-year dog study and upon which the RfD is based is
much lower than the NOELs defined in the reproduction and developmental
toxicology studies. Conservative assumptions utilized to estimate
aggregate dietary exposures of infants and children to rimsulfuron
demonstrated that only 1.95% of the RfD was utilized for current
tolerances (corn and potatoes) and the addition of tomatoes would only
increase utilization to 2.73% of the RfD for the highest exposed group.
Based on these exposure estimates and the fact that the current
database demonstrates that the developing offspring or young animals
are not uniquely susceptible to rimsulfuron administration, the extra
10-fold uncertainty factor is not warranted for these groups.
Therefore, it may be concluded that there is reasonable certainty that
no harm will result to infants and children from aggregate exposures to
rimsulfuron.

F. International Tolerances

    The following international tolerances (or Maximum Residue Levels,
MRL's) exist:

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Country           Tolerance in ppm                      Crop
---------------------------------------------------------------
Australia             0.05                             Tomatoes
Austria               0.1                          Corn, Potato
Belgium               0.05                                 Corn
Bulgaria              0.5                           Corn-Fodder
Canada                0.1                          Corn, Potato
Croatia               0.1                                Fodder
Czech. Rep.           0.05                  Corn, Grain, Potato
Germany               0.05                         Corn, Potato
Hungary               0.2                                  Corn
Italy                 0.10               Corn, Potato, Tomatoes
Romania               0.05                         Corn, Potato

[[Page 8642]]

Slovakia              0.05                          Corn, Grain
Spain                 0.05                       Corn, Tomatoes
United States         0.1                          Corn, Potato
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[FR Doc. 98-4187 Filed 2-19-98; 8:45 am]
BILLING CODE 6560-50-F