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Halosulfuron-Methyl - Pesticide Petition Filing 5/98

ENVIRONMENTAL PROTECTION AGENCY
[PF-806; FRL-5791-2]
Monsanto Company; Pesticide Tolerance Petitions Filing
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: This notice announces the initial filing of a pesticide
petition proposing the establishment of regulations for residues of a
certain pesticide chemical in or on various food commodities.

DATES: Comments, identified by the docket control number PF-806, must
be received on or before June 29, 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. 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: James A. Tompkins, Registration
Support Branch, 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: Rm.
239, Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA
22202, (703) 305-5697; e-mail: tompkins.james@epamail.epa.gov.
SUPPLEMENTARY INFORMATION: EPA has received a pesticide petition as
follows proposing the establishment and/or amendment of regulations for
residues of certain pesticide chemical 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 this petition
contains 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-806] (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 this proposed rule 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 14, 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 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. Monsanto Company

PP 8F4937

    EPA has received a pesticide petition (PP 8F4937) from Monsanto
Company, 700 14th St., NW., Suite 1100, Washington, DC 20005. 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

[[Page 29402]]

halosulfuron-methyl: methyl 5-[(4,6-dimethoxy-2-pyrimidinyl)amino]
carbonyl aminosulfonyl-3-chloro-1-methyl-1H-pyrazole-4-carboxylate in
or on the raw agricultural commodity undelinted cotton seed & cotton
gin by-products at 0.05 parts per million (ppm), rice grain at 0.05
ppm, rice straw at 0.20 ppm, tree nut group (Group 14) nutmeat at 0.05
ppm and hulls at 0.20 ppm, pistachio, nutmeat at 0.05 ppm, pistachio,
hulls at 0.2 ppm.
    In addition, Monsanto proposes the establishment of tolerances for
halosulfuron methyl (as parent only) in or on the following raw
agricultural commodities:
    Corn, field: grain at 0.05 ppm, forage at 0.2 ppm, and fodder at
0.8 ppm.
    Grain, sorghum (milo): grain at 0.05 ppm, forage at 0.05 ppm, and
fodder/stover at 0.10 ppm.
    Monsanto also proposes removing 40 CFR 180.479 (b) which reads as
follows:
    Indirect or inadvertent tolerances. Tolerances are established for
indirect or inadvertent residues of the herbicide halosulfuron-methyl
and its metabolites determined as 3-chloro-1-methyl-5-
sulfamoylpyrazole-4-carboxylic acid and expressed as parent
equivalents, in or on the following raw agricultural commodities when
present therein as a result of the application of halosulfuron-methyl
to growing crops.
    Soybean, forage at 0.5 ppm, soybean, hay at 0.5 ppm, soybean, seed
at 0.5 ppm, wheat, forage at 0.1 ppm, wheat, grain at 0.1 ppm. and
wheat, straw at 0.2 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 halosulfuron-methyl as well
as the nature of the residues in plants is adequately understood for
purposes of these tolerances. Metabolism studies were conducted in
three crops, viz.; field corn, sugarcane and soybeans. Metabolism
depends on the mode of application. Preemergent applications result in
rapid soil degradation of halosulfuron-methyl followed by crop uptake
of the resulting pyrazole moiety. The pyrimidine ring binds tightly to
soil and is eventually converted to carbon dioxide by microbial
degradation. In postemergent applications, little metabolism and
translocation take place resulting in unmetabolized parent compound as
the major residue on the directly treated foliar surfaces. Very low
residue levels of the metabolite 3-chloro-1-methyl-5-sulfamoylpyrazole-
4-carboxylic acid (3-CSA) are found in the grain.
    2. Analytical method. A practical analytical method, gas
chromatography with an electron- capture detector which detects and
measures total residues (halosulfuron-methyl and metabolites) is
available for enforcement purposes with a limit of detection that
allows monitoring of food with residues at or above the levels set in
these tolerances. This enforcement method has been submitted to the
Food and Drug Administration for publication in the Pesticide
Analytical Manual, Vol. II (PAM II). It has undergone independent
laboratory validation and validation at the Beltsville laboratory. The
Analytical Chemistry section of the EPA concluded that the method is
adequate for enforcement. Analytical method is also available for
analyzing meat by-products which also underwent successful independent
laboratory and Beltsville laboratory validations.
    3. Magnitude of residues. In the tree nut residue study, there were
no quantifiable residues found in nut meats using an analytical method
with limit of quantitation (LOQ) of 0.05 ppm. Residues ranging from
<0.05 to 0.154 ppm were found in almond hulls when treated at 1.4 times
the recommended rate. There were no detectable residues found in cotton
undelinted seed as well as from the resulting processed commodities
even at treatment rates of more than 5 times the maximum recommended
rate per season. No quantifiable residues were found in cotton gin
byproducts. The residues in the rice grain and rice processed fractions
were below the limit of detection of 0.02 ppm at all locations. 5 of
the 18 sites showed residues in rice straw ranging from 0.06 to 0.17
ppm while 13 sites had non-quantifiable residues (<0.05 ppm). Results
of the aquatic sediment dissipation study showed that the parent and
major metabolite residues dissipated rapidly in both soil and water
phases with DT50 values of 1.3 and 1.87 days and
DT90 of 6.48 and 12 days from 2 sites, respectively. The
half-life of halosulfuron-methyl in the paddy water phase is calculated
to be 0.87 days following direct application to water. The vertical
mobility is not a major route of dissipation. The residues (parent and
metabolites that are hydrolyzable to 3-CSA) dissipated rapidly in the
upper soil layer but showed no indication of significant downward
movement into the lower soil layers.

B. Toxicological Profile

    1. Acute toxicity. Acute toxicological studies placing the
technical-grade halosulfuron-methyl in Toxicity Category III. A 90-day
feeding study in rats resulted in a lowest-observed-effect-level (LOEL)
of 497 milligrams/kilograms/day (mg/kg/day) in males and 640 mg/kg/day
in females, and a no-observed-effect-level (NOEL) of 116 mg/kg/day in
males and 147 mg/kg/day in females.
    2. Genotoxicty. Bacterial/mammalian microsomal mutagenicity assays
were performed and found not to be mutagenic. Two mutagenicity studies
were performed to test gene mutation and found to produce no
chromosomal aberrations or gene mutations in cultured Chinese hamster
ovary cells. An in vivo mouse micronucleus assay did not cause a
significant increase in the frequency of micronucleated polychromatic
erythrocytes in bone marrow cells. A mutagenicity study was performed
on rats and found not to induce unscheduled DNA synthesis in primary
rat hepatocytes.
    3. Reproductive and developmental toxicity. A developmental
toxicity study in rats resulted in a developmental LOEL of 750 mg/kg/
day, based on decreases in mean litter size and fetal body weight, and
increases in resorptions, resorptions/dam, post-implantation loss and
in fetal and litter incidences of soft tissue and skeletal variations,
and a developmental NOEL of 250 mg/kg/day. Maternal LOEL was 750 mg/kg/
day based on increased incidence of clinical observations, reduced body
weight gains, and reduced food consumption and food efficiency. The
maternal NOEL was 250 mg/kg/day.
    A developmental toxicity study in rabbits resulted in a
developmental LOEL of 150 mg/kg/day, based on decreased mean litter
size and increases in resorptions, resorptions/dam and post-
implantation loss, and a developmental NOEL of 50 mg/kg/day. The
maternal LOEL was 150 mg/kg/day based on reduced body weight gain and
reduced food consumption and food efficiency. The maternal NOEL was 50
mg/kg/day.
    A dietary 2-generation reproduction study in rats resulted in
parental toxicity at 223.2 mg/kg/day in males and 261.4 mg/kg/day in
females in the form of decreased body weights, decreased body weight
gains, and reduced food consumption during the premating period. Very
slight effects were noted in body weight of the offspring at this dose.
This effect was

[[Page 29403]]

considered to be developmental toxicity (developmental delay) rather
than a reproductive effect. No effects were noted on reproductive or
other developmental toxicity parameters. The systemic/ developmental
toxicity LOEL was 223.2 mg/kg/day in males and 261.4 mg/kg/day in
females; the systemic/developmental toxicity NOEL was 50.4 mg/kg/day in
males and 58.7 mg/kg/day in females. The reproductive LOEL was greater
than 223.2 mg/kg/day in males and 261.4 mg/kg/day in females; the
reproductive NOEL was equal to or greater than 223.2 mg/kg/day in males
and 261.4 mg/kg/day in females.
    4. Subchronic toxicity. A 21-day dermal toxicity study in rats
resulted in a NOEL of 100 mg/kg/day in males and greater than 1,000 mg/
kg/day in females. The only treatment-related effect was a decrease in
body weight gain of the 1,000 mg/kg/day group in males.
    5. Chronic toxicity. A 1-year chronic oral study in dogs resulted
in a LOEL of 40 mg/kg/day based on decreased weight gain and a NOEL of
10 mg/kg/day for systemic toxicity. A 78-week carcinogenicity study was
performed on mice. Males in the 971.6 mg/kg/day group had decreased
body weight gains and an increased incidence of microconcretion/
mineralization in the testis and epididymis. No treatment-related
effects were noted in females. Based on these results, a LOEL of 971.9
mg/kg/day was established in males and NOELs of 410 mg/kg/day in males
and 1,214.6 mg/kg/day in females were established. The study showed no
evidence of carcinogenicity. A combined chronic toxicity/
carcinogenicity study in rats resulted in a LOEL of 225.2 mg/kg/day in
males and 138.6 mg/kg/day in females based on decreased body weight
gains, and a NOEL of 108.3 mg/kg/day in males and 56.3 mg/kg/day in
females. The study showed no evidence of carcinogenicity.
    6. Animal metabolism. EPA stated that the nature of the residue in
ruminants was determined to be adequately understood. In the tissues
and milk of goats, the major extractable residue was the unmetabolized
parent compound. Based on the low residues of the parent compound in
corn grain and the low transfer of residues in the metabolism study,
tolerances on poultry products were not required. In the rat metabolism
study, parent compound was absorbed rapidly but incompletely. Excretion
was relatively rapid at all doses tested with majority of radioactivity
eliminated in the urine and feces by 72 hours. Fecal elimination of
parent was apparently the result of unabsorbed parent.
    7. Metabolite toxicology. The toxicology studies listed below were
conducted with the 3-CSA metabolite. Based on the toxicological data of
the 3-CSA metabolite, EPA concluded that it has lower toxicity compared
to the parent compound and that it should not be included in the
tolerance expression. The residue of concern is the parent compound
only.
    i. A 90-day rat feeding study resulted in a LOEL in males of
>20,000 ppm and a NOEL of 20,000 ppm (1,400 mg/kg/day). In females, the
LEL is 10,000 ppm (772.8 mg/kg/day) based on decreased body weight
gains and a NOEL of 1,000 ppm (75.8 mg/kg/day).
    ii. A developmental toxicity resulted in a LOEL for maternal
toxicity of >1,000 mg/kg/day based on the absence of systemic toxicity,
a NOEL of 1,000 mg/kg/day. The developmental LOEL is >1,000 mg/kg/day
and the NOEL is 1,000 mg/kg/day.
    iii. The microbial reverse gene mutation did not produce any
mutagenic effect while the mammalian cell gene mutation/chinese hamster
ovary cells did not show a clear evidence of mutagenic effect in the
Chinese hamster ovary cells.
    iv. The mouse micronucleus assay did not show any clastogenic or
aneugenic effect.
    8. Endocrine disruption. No specific tests have been conducted with
halosulfuron-methyl to determine whether the chemical may have an
effect in humans that is similar to an effect produced by a naturally
occurring estrogen or other endocrine effects. However, there were no
significant findings in other relevant toxicity tests, i.e., teratology
and multi-generation reproduction studies, which would suggest that
halosulfuron-methyl produces effects characteristic of the disruption
of the estrogenic hormone.

C. Aggregate Exposure

    1. Dietary exposure-- i. Food. For purposes of assessing the
potential dietary exposure from food under existing tolerances,
aggregate exposure based on the Theoretical Maximum Residue
Contribution (TMRC) which is an estimate of the level of residues
consumed daily if each food item contained pesticide residues equal to
the tolerance. The calculated TMRC value was 0.0005 mg/kg body weight/
day for the general US population which will utilize only 0.51% of the
Reference Dose (RfD) for established tolerances for halosulfuron-methyl
and its metabolites in/on raw agricultural commodities of field corn,
grain sorghum (milo) and secondary tolerances in meat and meat
byproducts (cattle, goats, hogs, horses, and sheep). TMRC is obtained
by multiplying the tolerance levels for each commodity by the average
daily consumption of the food forms of that commodity eaten by the U.S.
population and various population subgroups. In conducting this
exposure assessment, conservative assumptions were made, e.g., 100% of
all commodities will contain halosulfuron-methyl residues and those
residues would be at the level of their respective tolerances. This
results in a large overestimate of human exposure. Monsanto conducted
another dietary exposure analysis to include food from crops in
subsequent petitions including this petition. This analysis added
dietary exposure from the following raw agricultural commodities using
the proposed tolerance levels of each commodity, viz.; sweet corn
(kernel + cobs with husks removed at 0.05 ppm, forage at 0.2 ppm,
fodder/stover at 0.8 ppm), pop corn (grain at 0.05 ppm, fodder/stover
at 0.8 ppm), sugarcane (cane at 0.05 ppm), tree nut crop grouping (nut
meat at 0.05 ppm, hulls at 0.2 ppm), pistachio nuts (nutmeat at 0.05
ppm, hulls at 0.2 ppm), cotton (undelinted seed at 0.05 ppm, gin
byproduct at 0.2 ppm) and rice (grain at 0.05 ppm and straw at 0.2
ppm). Food consumption data from the USDA Nationwide Food consumption
survey for 1989-1992 and the EXPOSURE-1 software by TAS, Inc. were used
in the calculation. Even with the same conservative assumptions, the
potential dietary exposure to halosulfuron-methyl from consumption of
products for which it is currently labeled and proposed resulted in a
TMRC of 0.00064 mg/kg body weight/day and represents only 0.6% of the
RfD for the general U.S. population. Field corn and sorghum forage and
fodder are fed to animals, thus exposure of humans to residues from
these commodities might result if such residues are transferred to
meat, milk, poultry or eggs. However, based on the results of animal
metabolism and the amount of halosulfuron-methyl expected in animal
feeds, Monsanto concludes that there is no reasonable expectation that
residues of halosulfuron-methyl will exceed existing tolerances in
meat. The regulation of animal commodities and poultry products are not
required.
    ii. Drinking water. There is no Maximum Contaminant Level (MCL)
established for residues of halosulfuron-methyl. It is not listed for
MCL development or drinking water monitoring under the Safe Drinking
Water Act nor is it a target of EPA's National Survey of Wells for
Pesticides.

[[Page 29404]]

Monsanto is not aware of any halosulfuron-methyl detections in any
wells, ponds, lakes or streams resulting from its use in the United
States. A Lifetime Health Advisory Level (HAL), calculated using EPA
procedures, may be used as a preliminary acceptable level in drinking
water. The calculated level is 700 ppb which assumes a 20% relative
contribution from water and which is sufficient to provide ample
margins of safety. In addition, EPA has concluded that potential levels
of halosulfuron-methyl or metabolites in soil and water do not appear
to have significant toxicological effects on humans or animals and
presents a negligible risk.
    The EPA has expressed concern regarding potential groundwater
contamination by the sulfonylurea (SU) class of chemistry in general
and has required generic label warnings for halosulfuron-methyl;
however, results of the field dissipation and lysimeter studies and a
recently completed aquatic sediment study with halosulfuron-methyl
should mitigate the concern for this chemical in particular.
    Based on the very low level of mammalian toxicity, lack of other
toxicological concerns and low use rates, Monsanto believes that there
is reasonable certainty that no harm will result from exposure to
halosulfuron-methyl via drinking water sources.
    iii. Non-dietary exposure. Halosulfuron-methyl is labeled for use
on commercial and residential turf and other non-crop sites which could
have minimal opportunity for exposure. The agricultural uses including
the proposed uses in tree nut crop group, pistachio nuts, cotton and
rice will not increase the non-occupational exposure appreciably, if at
all. Any exposure to halosulfuron-methyl resulting from turf use will
result from dermal exposure during application and will be limited
because of low use rates. In the 21-day dermal study, no treatment
related adverse effects were observed and the NOAEL was determined to
be greater than the highest dose tested, >1,000 mg/kg. Halosulfuron-
methyl is non-volatile with a vapor pressure of <1 x 10-7 mm
Hg, hence, inhalation exposure during and after application will not
add significantly to aggregate exposure. Based on the physical and
chemical characteristics, low use rates, low acute toxicity and lack of
other toxicological concerns, Monsanto believes that the risk posed by
non-occupational exposure to halosulfuron-methyl is minimal.

D. Cumulative Effects

    Halosulfuron-methyl belongs to the sulfonyl urea class of
chemistry. The mode of action of halosulfuron-methyl is the inhibition
of the plant enzyme aceto lactase synthetase (ALS), which is essential
for the production of required amino acid in plants. Although other
registered sulfonyl ureas may have similar herbicidal mode of action,
there is no information available to suggest that these compounds
exhibit a similar toxicity profile in the mammalian system that would
be cumulative with halosulfuron-methyl. Thus, consideration of a common
mechanism of toxicity is not appropriate at this time. Monsanto is
considering only the potential risks of halosulfuron-methyl in its
aggregate exposure assessment.

E. Safety Determination

    1. U.S. population--Chronic dietary exposure. As stated above, the
EPA's calculated aggregate chronic exposure to halosulfuron-methyl from
the established tolerances for field corn and grain sorghum raw
agricultural commodities utilizes only 0.51% of the RfD using very
conservative assumptions. Monsanto's subsequent calculation to include
the proposed tolerances on sweet corn, pop corn, sugarcane, tree nut
crop grouping, pistachio nuts, rice and cotton estimates that it will
utilize only 0.6% of the RfD for the entire U.S. population. 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. Toxicology data indicating low potential for mammalian toxicity
and lack of other toxicity concerns plus the conservative assumptions
used in this calculation support the conclusion that there is a
"reasonable certainty of no harm" to the U.S. population in general
from aggregate exposure to halosulfuron-methyl residues from all
anticipated dietary exposures and all other non-occupational exposures.
    2. Acute dietary exposure. The detailed DRES acute exposure
analysis evaluates individual food consumption and estimates the
distribution of single day exposures through the diet for the US
population and certain subgroups. Since the toxicological effect to
which high end exposure is compared is developmental toxicity, EPA
determined that the DRES subgroup of concern is females (13+ years)
which approximates women of child-bearing age. The appropriate NOEL to
use to assess safety in acute exposure is 50 mg/kg body weight/day from
a developmental toxicity study in rabbits.
    For shorter term risk, the Margin of Exposure (MOE), a measure of
how closely the high end exposure comes to the NOEL and is calculated
as a ratio of the NOEL to the exposure (NOEL/exposure = MOE). For
toxicological endpoints established based upon animal studies ,the
agency is generally not concerned unless the MOE is below 100. In this
analysis, tolerance levels were used to calculate the exposure of the
highest exposed individual (females, 13+ year subgroup). High end
exposure for this subgroup resulted in an MOE in excess of 30,000.
Therefore, the acute dietary exposure to halosulfuron-methyl does not
represent a risk concern. Monsanto has calculated the MOE for all
tolerances (established and proposed) which resulted in an MOE of
31,623 for the entire U.S. population. Monsanto's calculation used the
individual food consumption data from the 1989-1992 USDA Food
Consumption Surveys and the EXPOSURE-4 software by TAS, Inc. Therefore,
Monsanto concludes that there is a reasonable certainty that no harm
will result from acute aggregate exposure to halosulfuron-methyl
residues.
    3. Infants and children. In assessing the potential for additional
sensitivity of infants and children to residues of halosulfuron-methyl,
Monsanto considered data from developmental toxicity studies in the rat
and rabbit and a 2-generation reproduction study in the rat. The
developmental toxicity studies are designed to evaluate the potential
for adverse effects on the developing organism resulting from exposure
during prenatal development to the female parent. Reproduction studies
provide information relating to effects from exposure to the chemical
on the reproductive capability of both (mating) parents and on off
spring from pre-natal and post-natal exposure to the pesticide as well
as systemic toxicity.
    In a developmental toxicity study in the rat, the NOEL for both
maternal and developmental toxicity was considered to be 250 mg/kg/day.
In a developmental toxicity study in rabbits, a NOEL for both
developmental and maternal toxicity was considered to be 50 mg/kg/day.
A dietary 2-generation reproduction study in rats resulted in parental
toxicity at 223.2 mg/kg/day in males and 261.4 mg/kg/day in females in
the form of decreased body weights, decreased body weight gains, and
reduced food consumption during the premating period. Very slight
effects were noted in body weight of the offspring at this dose. This
effect was

[[Page 29405]]

considered to be developmental toxicity (developmental delay) rather
than a reproductive effect. No effects were noted on reproductive or
other developmental toxicity parameters. The systemic/developmental
toxicity NOEL was 50.4 mg/kg/day in males and 58.7 mg/kg/day in
females. The reproductive NOEL was equal to or greater than 223.2 mg/
kg/day in males and 261.4 mg/kg/day in females. In all cases, the
reproductive and developmental NOELs were greater than the NOEL on
which the RfD was based, thus allowing for an additional margin of
safety and indicating that halosulfuron-methyl does not pose any
increased risk to infants or children.
    4. Chronic analysis. Using the conservative dietary exposure
assumptions described above, the TMRC for the most exposed subgroups is
0.00117 mg/kg body weight/day for nonnursing infants (less than 1-year
old) and 0.001008 mg/kg body weight/day for children (1 to 6 years
old), and that this aggregate exposure to residues of halosulfuron-
methyl utilizes only 1.170 and 1.008% of the RfD, respectively when
existing tolerances are considered. Monsanto's subsequent analysis
included contribution from the proposed tolerances in sugarcane, sweet
corn/popcorn, tree nut crop grouping, pistachio nuts, rice and cotton.
The TMRC utilized only 1.7 and 1.3% of the RfD, respectively.
    FFDCA section 408 provides that EPA may apply an additional safety
factor (up to 10) in the case of threshold effects for infants and
children to account for pre- and post-natal toxicity and the
completeness of the data base. Based on current toxicological data
requirements, the data base relative to pre- and post-natal effects in
children is complete. Further, the NOEL of 10 mg/kg/day from the 1-year
feeding study in dogs, which was used to calculate the RfD (discussed
above), is already lower than the NOELs from the reproductive and
developmental studies with halosulfuron-methyl by a factor of at least
25- and 5-fold, respectively. An additional safety factor is not
warranted and the RfD of 0.1 mg/kg/day is appropriate for assessing
aggregate risk to infants and children.
    Therefore, based on complete and reliable toxicity data and the
conservative exposure assessment, Monsanto concludes that there is
reasonable certainty that no harm will result to infants and children
from aggregate exposure to halosulfuron-methyl residues.

F. International Tolerances

    Maximum residue levels have not been established for residues of
halosulfuron-methyl on corn, sorghum, sugarcane, sweet corn, pop corn,
tree nuts, pistachio nuts, rice or cotton or any other food or feed
crop by the Codex Alimentarius Commission.

 [FR Doc. 98-14160 Filed 5-28-98; 8:45 am]
BILLING CODE 6560-50-F