[Federal Register Volume 75, Number 249 (Wednesday, December 29, 2010)]
[Rules and Regulations]
[Pages 81878-81885]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-32451]



40 CFR Part 180

 [EPA-HQ-OPP-2009-0205; FRL-8857-4]

Imazosulfuron; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.


SUMMARY: This regulation establishes tolerances for residues of 
imazosulfuron in or on pepper, bell; pepper, non-bell; rice, grain; and 
tomato. Valent USA Corporation requested these tolerances under the 
Federal Food, Drug, and Cosmetic Act (FFDCA).

DATES: This regulation is effective December 29, 2010. Objections and 
requests for hearings must be received on or before February 28, 2011, 
and must be filed in accordance with the instructions provided in 40 
CFR part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).

[[Page 81879]]

ADDRESSES: EPA has established a docket for this action under docket 
identification (ID) number EPA-HQ-OPP-2009-0205. All documents in the 
docket are listed in the docket index available at http://www.regulations.gov. Although listed in the index, some information is 
not publicly available, e.g., Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. Certain 
other material, such as copyrighted material, is not placed on the 
Internet and will be publicly available only in hard copy form. 
Publicly available docket materials are available in the electronic 
docket at http://www.regulations.gov, or, if only available in hard 
copy, at the OPP Regulatory Public Docket in Rm. S-4400, One Potomac 
Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. The Docket 
Facility is open from 8:30 a.m. to 4 p.m., Monday through Friday, 
excluding legal holidays. The Docket Facility telephone number is (703) 

FOR FURTHER INFORMATION CONTACT: Susan Stanton, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 305-5218; e-mail address: stanton.susan@epa.gov.


I. General Information

A. Does this action apply to me?

    You may be potentially affected by this action if you are an 
agricultural producer, food manufacturer, or pesticide manufacturer. 
Potentially affected entities may include, but are not limited to those 
engaged in the following activities:
     Crop production (NAICS code 111).
     Animal production (NAICS code 112).
     Food manufacturing (NAICS code 311).
     Pesticide manufacturing (NAICS code 32532).
    This listing is not intended to be exhaustive, but rather to 
provide a guide for readers regarding entities likely to be affected by 
this action. Other types of entities not listed in this unit could also 
be affected. The North American Industrial Classification System 
(NAICS) codes have been provided to assist you and others in 
determining whether this action might apply to certain entities. If you 
have any questions regarding the applicability of this action to a 
particular entity, consult the person listed under FOR FURTHER 

B. How can I get electronic access to other related information?

    You may access a frequently updated electronic version of EPA's 
tolerance regulations at 40 CFR part 180 through the Government 
Printing Office's e-CFR site at http://www.gpoaccess.gov/ecfr. To 
access the harmonized test guidelines referenced in this document 
electronically, please go http://www.epa.gov/ocspp and select ``Test 
Methods and Guidelines.''

C. How can I file an objection or hearing request?

    Under FFDCA section 408(g), 21 U.S.C. 346a, any person may file an 
objection to any aspect of this regulation and may also request a 
hearing on those objections. You must file your objection or request a 
hearing on this regulation in accordance with the instructions provided 
in 40 CFR part 178. To ensure proper receipt by EPA, you must identify 
docket ID number EPA-HQ-OPP-2009-0205 in the subject line on the first 
page of your submission. All objections and requests for a hearing must 
be in writing, and must be received by the Hearing Clerk on or before 
February 28, 2011. Addresses for mail and hand delivery of objections 
and hearing requests are provided in 40 CFR 178.25(b).
    In addition to filing an objection or hearing request with the 
Hearing Clerk as described in 40 CFR part 178, please submit a copy of 
the filing that does not contain any CBI for inclusion in the public 
docket. Information not marked confidential pursuant to 40 CFR part 2 
may be disclosed publicly by EPA without prior notice. Submit a copy of 
your non-CBI objection or hearing request, identified by docket ID 
number EPA-HQ-OPP-2009-0205, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the online instructions for submitting comments.
     Mail: Office of Pesticide Programs (OPP) Regulatory Public 
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460-0001.
     Delivery: OPP Regulatory Public Docket (7502P), 
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South 
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only 
accepted during the Docket Facility's normal hours of operation (8:30 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays). 
Special arrangements should be made for deliveries of boxed 
information. The Docket Facility telephone number is (703) 305-5805.

II. Summary of Petitioned-For Tolerance

    In the Federal Register of May 6, 2009 (74 FR 20947) (FRL-8412-7), 
EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21 U.S.C. 
346a(d)(3), announcing the filing of a pesticide petition (PP 9F7535) 
by Valent USA Corporation, 1600 Riviera Ave., Suite 200, Walnut Creek, 
CA 94596. The petition requested that 40 CFR part 180 be amended by 
adding a section for the herbicide imazosulfuron and establishing 
tolerances therein for residues of imazosulfuron, 2-chloro-N-[[(4,6-
dimethoxy-2-pyrimidinyl)amino]carbonyl] imidazo-[1,2-a]pyridine-3-
sulfonamide, in or on pepper, bell, fruit; pepper, non-bell, fruit; 
rice, grain; and tomato, fruit; each at 0.02 parts per million (ppm). 
That notice referenced a summary of the petition prepared by Valent USA 
Corporation, the registrant, which is available in the docket, http://www.regulations.gov. There were no comments received in response to the 
notice of filing.
    EPA has modified the proposed commodity terms for pepper and tomato 
commodities and revised the requested tolerance expression in 
accordance with current policy. The reasons for these changes are 
explained in Unit IV.C.

III. Aggregate Risk Assessment and Determination of Safety

    Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a 
tolerance (the legal limit for a pesticide chemical residue in or on a 
food) only if EPA determines that the tolerance is ``safe.'' Section 
408(b)(2)(A)(ii) of FFDCA defines ``safe'' to mean that ``there is a 
reasonable certainty that no harm will result from aggregate exposure 
to the pesticide chemical residue, including all anticipated dietary 
exposures and all other exposures for which there is reliable 
information.'' This includes exposure through drinking water and in 
residential settings, but does not include occupational exposure. 
Section 408(b)(2)(C) of FFDCA requires EPA to give special 
consideration to exposure of infants and children to the pesticide 
chemical residue in establishing a tolerance and to ``ensure that there 
is a reasonable certainty that no harm will result to infants and 
children from aggregate exposure to the pesticide chemical residue. * * 
    Consistent with section 408(b)(2)(D) of FFDCA, and the factors 
specified in section 408(b)(2)(D) of FFDCA, EPA has reviewed the 
available scientific data and other relevant information in support of 
this action. EPA has

[[Page 81880]]

sufficient data to assess the hazards of and to make a determination on 
aggregate exposure for imazosulfuron including exposure resulting from 
the tolerances established by this action. EPA's assessment of 
exposures and risks associated with imazosulfuron follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
    The toxicology data for imazosulfuron suggest that this herbicide 
possesses relatively low toxicity. Many of the effects of single or 
repeated dosing were observed near or beyond the respective limit 
    Imazosulfuron is of low acute toxicity by the oral, dermal, and 
inhalation routes of exposure; it is not a skin or eye irritant or a 
dermal sensitizer. The primary target organ of imazosulfuron in 
repeated-dose studies was the liver in all species tested. Mild to 
moderate thyroid effects were apparent only in the chronic toxicity 
study in dogs. Dramatic eye effects (retinal degeneration, lens 
vascularization, cataracts and corneal scarring) were observed in rats 
fed > 1,000 mg/kg/day beginning at 3 months in the chronic toxicity/
carcinogenicity study. Ocular effects (increased incidence of eye 
opacity, corneal edema, inflammation and neovascularization) were also 
observed in the high-dose males (4,577 mg/kg/day) in the 90-day feeding 
toxicity study in rats. Decreased body weight and body weight gain 
compared to control were frequent findings throughout the toxicology 
database for imazosulfuron.
    Clinical signs (decreased motor activity, abnormal gait, upward 
curvature of the spine and piloerection) were observed in males at the 
limit dose of the acute neurotoxicity study; however, these effects can 
be attributed to generalized toxicity and were resolved by Day 2 of the 
study. No neurotoxic effects were observed during the subchronic 
screening battery or noted as clinical signs in any other repeated-dose 
    No developmental effects were observed at the highest dose tested 
(HDT) (125 mg/kg/day) in the rabbit developmental toxicity study. No 
developmental or reproductive toxicity was observed in the 1-generation 
rat study. Decreased pup viability was observed in the rat 2-generation 
reproduction study at a dose approaching the limit dose (LOAEL = 892 
mg/kg/day) in both the F1 and F2 offspring generations. Mortality was 
also observed in the parental generation at this dose. No increased 
qualitative or quantitative offspring susceptibility was apparent in 
any of the submitted studies for imazosulfuron.
    There was no evidence of carcinogenicity in rats and mice up to the 
limit dose at 24 and 18 months, respectively. Imazosulfuron was 
determined to be non-mutagenic in bacteria and negative in an in vivo 
mammalian cytogenetics assay. Overall, there was no evidence that 
imazosulfuron was either mutagenic or clastogenic in either in vivo or 
in vitro assays. The cancer classification is ``not likely to be 
carcinogenic to humans,'' based on the absence of significant tumor 
increases in the carcinogenicity studies.
    Specific information on the studies received and the nature of the 
adverse effects caused by imazosulfuron as well as the no-observed-
adverse-effect-level (NOAEL) and the lowest-observed-adverse-effect-
level (LOAEL) from the toxicity studies can be found at http://www.regulations.gov in the document ``Imazosulfuron: Human Health Risk 
Assessment for Proposed Uses on Rice, Peppers and Tomatoes,'' p. 45 in 
docket ID number EPA-HQ-OPP-2009-0205.

B. Toxicological Points of Departure/Levels of Concern

    Once a pesticide's toxicological profile is determined, EPA 
identifies toxicological points of departure (POD) and levels of 
concern to use in evaluating the risk posed by human exposure to the 
pesticide. For hazards that have a threshold below which there is no 
appreciable risk, the toxicological POD is used as the basis for 
derivation of reference values for risk assessment. PODs are developed 
based on a careful analysis of the doses in each toxicological study to 
determine the dose at which no adverse effects are observed (the NOAEL) 
and the lowest dose at which adverse effects of concern are identified 
(the LOAEL). Uncertainty/safety factors are used in conjunction with 
the POD to calculate a safe exposure level--generally referred to as a 
population-adjusted dose (PAD) or a reference dose (RfD)--and a safe 
margin of exposure (MOE). For non-threshold risks, the Agency assumes 
that any amount of exposure will lead to some degree of risk. Thus, the 
Agency estimates risk in terms of the probability of an occurrence of 
the adverse effect expected in a lifetime. For more information on the 
general principles EPA uses in risk characterization and a complete 
description of the risk assessment process, see http://www.epa.gov/pesticides/factsheets/riskassess.htm. A summary of the toxicological 
endpoints for imazosulfuron used for human risk assessment is shown in 
the Table of this unit.

  Table--Summary of Toxicological Doses and Endpoints for Imazosulfuron for Use in Human Health Risk Assessment
                                      Point of departure and
         Exposure/Scenario              uncertainty/safety    RfD, PAD, LOC for risk    Study and toxicological
                                             factors                assessment                  effects
Acute dietary (Females 13-49 years    An acute reference dose specific to females age 13-49 was not identified,
 of age).                              because there was no prenatal or fetal toxicity observed in developmental
                                             or reproductive animal studies following a single oral dose.
Acute dietary (General population    NOAEL = 400 mg/kg/day    Acute RfD = 4 mg/kg/    Acute neurotoxicity
 including females 13-49 years of     UFA = 10x.               day.                    screening battery.
 age and infants and children).                                                       LOAEL = 2,000 mg/kg/day
                                                                                       based on the following
                                                                                       clinical signs: Abnormal
                                                                                       gait, decreased activity,
                                                                                       piloerection and upward
                                                                                       curvature of the spine;
                                                                                       and incidents of
                                                                                       irregular breathing,
                                                                                       reduced righting reflex,
                                                                                       tremors, decreased visual
                                                                                       placement response in
                                                                                       males and increased
                                                                                       response to sound in one

[[Page 81881]]

                                     UFH = 10x..............  aPAD = 4 mg/kg/day
                                     FQPA SF = 1x...........
Chronic dietary (All populations)..  NOAEL= 75 mg/kg/day UFA  Chronic RfD = 0.75 mg/  Chronic toxicity in the
                                      = 10x.                   kg/day.                 dog.
                                                                                      LOAEL = 150 mg/kg/day
                                                                                       based on moderate thyroid
                                                                                       hypertrophy (males at mid-
                                                                                        and high-dose; mild
                                                                                       hypertrophy in females at
                                     UFH = 10x..............  cPAD = 0.75 mg/kg/day.
                                     FQPA SF = 1x...........
Incidental oral short-term (1 to 30  NOAEL= 235 mg/kg/day     LOC for MOE = 100.....  Reproduction, 2-generation
 days) and intermediate-term (1 to    UFA = 10x.                                       (rat).
 6 months).                                                                           LOAEL = 892 mg/kg/day
                                                                                       based on mortality,
                                                                                       clinical signs, decreased
                                                                                       body weights, body weight
                                                                                       gains and food
                                                                                       consumption in parents.
                                                                                      90-day oral toxicity
                                                                                      LOAEL = 956 mg/kg/day
                                                                                       based on decreased body
                                                                                       weight gains and food
                                     UFH = 10x..............
                                     FQPA SF = 1x...........
Dermal short-term (1 to 30 days)        No systemic toxicity occurred at the limit dose and the primary toxic
 and intermediate-term (1 to 6           effects of concern (liver, eye) were adequately assessed in a 21-day
 months).                               dermal toxicity study. It is concluded that this compound is not or is
                                         poorly absorbed through the skin and, therefore, a quantitative risk
                                         assessment for this route and duration of exposure is not necessary.
Inhalation short-term (1 to 30       Inhalation (or oral)     LOC for MOE = 100.....  Reproduction, 2-generation
 days) and intermediate-term (1 to    study NOAEL = 235 mg/                            (rat).
 6 months).                           kg/day (inhalation                              LOAEL = 892 mg/kg/day
                                      absorption rate =                                based on mortality,
                                      100%).                                           clinical signs, decreased
                                                                                       body weights, body weight
                                                                                       gains and food
                                                                                       consumption in parents.
                                     UFA = 10x..............
                                     UFH = 10x..............
                                     FQPA SF = 1x...........  ......................  90-day oral toxicity
                                                                                       (rat). LOAEL = 956 mg/kg/
                                                                                       day based on decreased
                                                                                       body weight gains and
                                                                                       food efficiency.
Cancer (Oral, dermal, inhalation)..    Classification: ``Not likely to be Carcinogenic to Humans'' based on the
                                             absence of significant tumor increases in two adequate rodent
                                                               carcinogenicity studies.
UFA = extrapolation from animal to human (interspecies). UFH = potential variation in sensitivity among members
  of the human population (intraspecies). UFL = use of a LOAEL to extrapolate a NOAEL. UFS = use of a short-term
  study for long-term risk assessment. UFDB = to account for the absence of data or other data deficiency. FQPA
  SF = Food Quality Protection Act Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD =
  reference dose. MOE = margin of exposure. LOC = level of concern.

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. In evaluating dietary 
exposure to imazosulfuron, EPA considered exposure under the 
petitioned-for tolerances. There are no tolerances currently 
established for imazosulfuron. EPA assessed dietary exposures from 
imazosulfuron in food as follows:
    i. Acute exposure. Quantitative acute dietary exposure and risk 
assessments are performed for a food-use pesticide, if a toxicological 
study has indicated the possibility of an effect of concern occurring 
as a result of a 1-day or single exposure. Such effects were identified 
for imazosulfuron. In estimating acute dietary exposure, EPA used food 
consumption information from the United States Department of 
Agriculture (USDA) 1994-1996 and 1998 Nationwide Continuing Surveys of 
Food Intakes by Individuals (CSFII). As to residue levels in food, EPA 
assumed that residues are present in all commodities at the tolerance 
level and that 100% of commodities are treated with imazosulfuron. 
DEEMTM 7.81 default concentration factors were used to 
estimate residues of imazosulfuron in processed commodities.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the food consumption data from the USDA 1994-1996 
and 1998 CSFII. As to residue levels in food, EPA assumed that residues 
are present in all commodities at the tolerance level and that 100% of 
commodities are treated with imazosulfuron. DEEMTM 7.81 
default concentration factors were used to estimate residues of 
imazosulfuron in processed commodities.
    iii. Cancer. Based on the results of carcinogenicity studies in 
rats and mice, EPA classified imazosulfuron as ``Not likely to be 
Carcinogenic to Humans''; therefore, a dietary exposure assessment for 
the purpose of assessing cancer risk is unnecessary.
    iv. Anticipated residue and percent crop treated (PCT) information. 
EPA did not use anticipated residue or PCT information in the dietary 
assessment for imazosulfuron. Tolerance level residues and 100 PCT were 
assumed for all food commodities.
    2. Dietary exposure from drinking water. The residues of concern in 
drinking water include imazosulfuron and its degradates HMS, IPSN, 
UDPM, ADPM, and SDPM. The Agency used screening level water exposure 
models in the dietary exposure analysis and risk assessment for 
imazosulfuron and its degradates in drinking water. These simulation 
models take into account data on the physical, chemical, and fate/
transport characteristics of imazosulfuron and its degradates. Further 
information regarding EPA

[[Page 81882]]

drinking water models used in pesticide exposure assessment can be 
found at http://www.epa.gov/oppefed1/models/water/index.htm.
    Based on the First Index Reservoir Screening Tool (FIRST), Tier 1 
Rice Model, and Screening Concentration in Ground Water (SCI-GROW) 
models, the estimated drinking water concentrations (EDWCs) of 
imazosulfuron and its degradates for both acute exposures and chronic 
exposures for non-cancer assessments are estimated to be 278.9 parts 
per billion (ppb) for surface water (based on the Tier 1 Rice Model 
results) and 4.8 ppb for ground water (based on the SCI-GROW model 
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model. For acute and chronic dietary 
risk assessment, the water concentration value of 278.9 ppb was used to 
assess the contribution to drinking water.
    3. From non-dietary exposure. The term ``residential exposure'' is 
used in this document to refer to non-occupational, non-dietary 
exposure (e.g., for lawn and garden pest control, indoor pest control, 
termiticides, and flea and tick control on pets). Imazosulfuron is 
currently registered for the following uses that could result in 
residential exposures: Residential turfgrass and recreational areas. 
EPA assessed residential exposure using the following assumptions: 
There is a potential for exposure of homeowners applying products 
containing imazosulfuron on home lawns. There is also a potential for 
post-application exposure of adults and children entering turf areas 
that have been treated with imazosulfuron and for bystander exposure of 
adults and children in areas adjacent to pesticide applications.
    Residential handlers may receive short-term dermal and inhalation 
exposure to imazosulfuron when mixing, loading and applying the 
pesticide on home lawns. Since a dermal endpoint of concern was not 
identified for imazosulfuron, only short-term inhalation exposure of 
residential handlers was assessed.
    Adults and children may receive short-term inhalation and dermal 
exposures from entering turf areas treated with imazosulfuron. 
Volatilization of imazosulfuron may also be a source of short-term 
post-application inhalation exposure of bystanders nearby application 
sites. Finally, children may receive short-term incidental oral 
exposure (i.e., hand-to-mouth, object-to-mouth and soil ingestion 
exposure) during post-application activities on treated turf. EPA did 
not identify any dermal endpoints of concern for imazosulfuron; and a 
quantitative post-application inhalation exposure assessment was not 
performed for imazosulfuron due to its low acute inhalation toxicity, 
low vapor pressure (< 3.5 x 10-6 Pa), low proposed use rate 
(0.3 lb ai/A), and the soil-directed application method (i.e., it is 
not applied using equipment, such as air blast sprayers, that would 
result in higher post-application inhalation exposures). Therefore, EPA 
assessed only short-term post-application incidental oral exposure of 
children (toddlers).
    Further information regarding EPA standard assumptions and generic 
inputs for residential exposures may be found at http://www.epa.gov/pesticides/trac/science/trac6a05.pdf.
    4. Cumulative effects from substances with a common mechanism of 
toxicity. Section 408(b)(2)(D)(v) of FFDCA requires that, when 
considering whether to establish, modify, or revoke a tolerance, the 
Agency consider ``available information'' concerning the cumulative 
effects of a particular pesticide's residues and ``other substances 
that have a common mechanism of toxicity.''
    EPA has not found imazosulfuron to share a common mechanism of 
toxicity with any other substances, and imazosulfuron does not appear 
to produce a toxic metabolite produced by other substances. For the 
purposes of this tolerance action, therefore, EPA has assumed that 
imazosulfuron does not have a common mechanism of toxicity with other 
substances. For information regarding EPA's efforts to determine which 
chemicals have a common mechanism of toxicity and to evaluate the 
cumulative effects of such chemicals, see EPA's Web site at  http://www.epa.gov/pesticides/cumulative.

D. Safety Factor for Infants and Children

    1. In general. Section 408(b)(2)(C) of FFDCA provides that EPA 
shall apply an additional tenfold (10X) margin of safety for infants 
and children in the case of threshold effects to account for prenatal 
and postnatal toxicity and the completeness of the database on toxicity 
and exposure unless EPA determines based on reliable data that a 
different margin of safety will be safe for infants and children. This 
additional margin of safety is commonly referred to as the FQPA Safety 
Factor (SF). In applying this provision, EPA either retains the default 
value of 10X, or uses a different additional safety factor when 
reliable data available to EPA support the choice of a different 
    2. Prenatal and postnatal sensitivity. The pre- and postnatal 
toxicity database for imazosulfuron includes guideline rat and rabbit 
developmental toxicity studies and a 2-generation reproduction toxicity 
study in rats. No developmental effects were observed at the HDT in the 
rabbit developmental toxicity study, and no developmental or 
reproductive toxicity was observed in the developmental (1-generation) 
rat study. In the 2-generation rat reproduction study, both decreased 
pup viability and parental mortality were observed, but only at a dose 
approaching the limit dose.
    3. Conclusion. EPA has determined that reliable data show the 
safety of infants and children would be adequately protected if the 
FQPA SF were reduced to 1X. That decision is based on the following 
    i. The toxicity database for imazosulfuron is largely complete, 
lacking only an immunotoxicity study. EPA has evaluated the available 
toxicity data for imazosulfuron and determined that an additional 
database uncertainty factor is not needed to account for potential 
immunotoxicity. The most sensitive endpoint in the database is moderate 
thyroid hypertrophy. Liver toxicity accompanied by body weight and food 
consumption effects is seen throughout the toxicology database. No 
treatment-related changes indicative of potential immunotoxicity were 
seen in hematology parameters, organ weights (thymus, spleen), gross 
necropsy (enlarged lymph nodes) or histopathology (spleen, thymus, 
lymph nodes) when tested up to the limit dose in mice and rats. 
Therefore, EPA does not believe that conducting a special series 
870.7800 immunotoxicity study will result in a NOAEL less than 75 mg/
kg/day, which is presently used as the point of departure for chronic 
risk assessment.
    ii. No neurotoxic effects were observed during the subchronic 
screening battery or noted as clinical signs in any other repeated-dose 
study. Although untoward clinical signs were observed in the acute 
neurotoxicity study, these effects can be attributed to generalized 
toxicity and were resolved by Day 2 of the study. Based on these 
considerations, there is no need for a developmental neurotoxicity 
study or additional UFs to account for neurotoxicity.
    iii. There is no evidence that imazosulfuron results in increased 
susceptibility in in utero rats or rabbits in the prenatal 
developmental studies or in young rats in the 2-generation reproduction 

[[Page 81883]]

    iv. There are no significant residual uncertainties in the exposure 
databases. Data have been requested to confirm the stability of 
imazosulfuron during frozen storage and the metabolic profile of 
pyrimidine-labeled imazosulfuron in rice grain in the confined 
rotational crop trial. A field rotational crop study is also required 
for grain (wheat); however, as explained in Unit III.D.3.iv.c., EPA 
does not expect these studies to have a measurable impact on exposure 
estimates for imazosulfuron.
    a. Storage stability. The final reports of the storage stability 
studies must be submitted, reflecting frozen storage intervals of up to 
11.8 months for peppers, up to 34.5 months for rice grain, and up to 
17.3 months for tomatoes. Interim data suggest that imazosulfuron is 
stable in frozen storage, and similar sulfonylurea chemicals are known 
to be stable. Therefore, EPA expects imazosulfuron to be stable in 
frozen storage but is requiring the final study reports as 
    b. Metabolic profile. The HPLC profile for the pyrimidinyl (Py)-
label grain storage stability analysis must be submitted to confirm 
that the metabolite profile was stable in Py-label grain. Grain samples 
from the confined rotational crop study were stored for a relatively 
long interval (9 months) prior to completion of the analyses. Analysis 
of an imidozolyl (Im)-label sample after the 9-month period yielded a 
metabolic profile similar to that of a sample analyzed at the start of 
the period. A similar comparison must be made for the Py-label sample 
of grain. This is of no practical consequence for risk assessment 
because total residue levels on grain were small (<0.01 ppm at a 365-
day plantback interval), imazosulfuron was not present, and no 
metabolites/degradates were considered toxicologically significant.
    c. Field accumulation in rotational crops (grain). The grain 
(wheat) rotational crop study is needed to identify maximum levels of 
residues in grain and livestock feed items (forage, straw) as a 
function of the plantback interval. On an interim basis, a plantback 
interval of 12 months is being required for grains and soybeans. The 
results of the rotational crop study may allow a shorter plantback 
interval. The confined rotational crop study showed that imazosulfuron 
and metabolites will be negligible (<0.01 ppm) on forage, hay, straw, 
stover, and grain at a 365-day plantback interval and will, therefore, 
make no contribution to dietary exposure.
    The dietary food exposure assessments were performed assuming 
tolerance-level residues and 100 PCT for all commodities. EPA made 
conservative (protective) assumptions in the ground and surface water 
modeling used to assess exposure to imazosulfuron in drinking water. 
EPA used similarly conservative assumptions to assess postapplication 
exposure of children as well as incidental oral exposure of toddlers. 
These assessments will not underestimate the exposure and risks posed 
by imazosulfuron.

E. Aggregate Risks and Determination of Safety

    EPA determines whether acute and chronic dietary pesticide 
exposures are safe by comparing aggregate exposure estimates to the 
acute PAD (aPAD) and chronic PAD (cPAD). For linear cancer risks, EPA 
calculates the lifetime probability of acquiring cancer given the 
estimated aggregate exposure. Short-, intermediate-, and chronic-term 
risks are evaluated by comparing the estimated aggregate food, water, 
and residential exposure to the appropriate PODs to ensure that an 
adequate MOE exists.
    1. Acute risk. An acute aggregate risk assessment takes into 
account acute exposure estimates from dietary consumption of food and 
drinking water. Using the exposure assumptions discussed in this unit 
for acute exposure, the acute dietary exposure from food and water to 
imazosulfuron will occupy 1.4% of the aPAD for infants less than 1 year 
old, the population group receiving the greatest exposure.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that chronic exposure to 
imazosulfuron from food and water will utilize 2.7% of the cPAD for 
infants less than 1 year old, the population group receiving the 
greatest exposure. Based on the explanation in Unit III.C.3., regarding 
residential use patterns, chronic residential exposure to residues of 
imazosulfuron is not expected.
    3. Short-term risk. Short-term aggregate exposure takes into 
account short-term residential exposure plus chronic exposure to food 
and water (considered to be a background exposure level). Imazosulfuron 
is currently registered for uses that could result in short-term 
residential exposure, and the Agency has determined that it is 
appropriate to aggregate chronic exposure through food and water with 
short-term residential exposures to imazosulfuron.
    Using the exposure assumptions described in this unit for short-
term exposures, EPA has concluded the combined short-term food, water, 
and residential exposures result in aggregate MOEs of 40,000 for adults 
and 7,000 for children. For adults, the aggregate MOE includes short-
term residential handler inhalation exposure plus chronic dietary 
exposure to imazosulfuron from food and water. For children, the 
aggregate MOE includes short-term incidental oral residential exposure 
plus chronic dietary exposure to imazosulfuron from food and water. 
Because EPA's level of concern for imazosulfuron is a MOE of 100 or 
below, these MOEs are not of concern.
    4. Intermediate-term risk. Intermediate-term aggregate exposure 
takes into account intermediate-term residential exposure plus chronic 
exposure to food and water (considered to be a background exposure 
level). An intermediate-term adverse effect was identified; however, 
imazosulfuron is not registered for any use patterns that would result 
in intermediate-term residential exposure. Intermediate-term risk is 
assessed based on intermediate-term residential exposure plus chronic 
dietary exposure. Because there is no intermediate-term residential 
exposure and chronic dietary exposure has already been assessed under 
the appropriately protective cPAD (which is at least as protective as 
the POD used to assess intermediate-term risk), no further assessment 
of intermediate-term risk is necessary, and EPA relies on the chronic 
dietary risk assessment for evaluating intermediate-term risk for 
    5. Aggregate cancer risk for U.S. population. Based on the lack of 
evidence of carcinogenicity in two adequate rodent carcinogenicity 
studies, imazosulfuron is not expected to pose a cancer risk to humans.
    6. Determination of safety. Based on these risk assessments, EPA 
concludes that there is a reasonable certainty that no harm will result 
to the general population, or to infants and children, from aggregate 
exposure to imazosulfuron residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (liquid chromatography/mass 
spectrometry/mass spectrometry (LC/MS/MS) Method RM-42C-3) is available 
to enforce the tolerance expression. The method may be requested from: 
Chief, Analytical Chemistry Branch, Environmental Science Center, 701 
Mapes Rd., Ft. Meade, MD 20755-5350; telephone number: (410) 305-2905; 
e-mail address: residuemethods@epa.gov.

[[Page 81884]]

B. International Residue Limits

    In making its tolerance decisions, EPA seeks to harmonize U.S. 
tolerances with international standards whenever possible, consistent 
with U.S. food safety standards and agricultural practices. EPA 
considers the international maximum residue limits (MRLs) established 
by the Codex Alimentarius Commission (Codex), as required by FFDCA 
section 408(b)(4). The Codex Alimentarius is a joint U.N. Food and 
Agriculture Organization/World Health Organization food standards 
program, and it is recognized as an international food safety 
standards-setting organization in trade agreements to which the United 
States is a party. EPA may establish a tolerance that is different from 
a Codex MRL; however, FFDCA section 408(b)(4) requires that EPA explain 
the reasons for departing from the Codex level.
    The Codex has not established a MRL for imazosulfuron.

C. Revisions to Petitioned-For Tolerances

    EPA is revising the proposed commodity terms for ``pepper, bell, 
fruit''; ``pepper, non-bell, fruit''; and ``tomato, fruit''; to read 
``pepper, bell''; ``pepper, non-bell''; and ``tomato''. The commodity 
terms have been changed in accordance with the guidance in the Agency's 
Food and Feed Commodity Vocabulary.
    EPA is also revising the requested tolerance expression to clarify 
the chemical moieties that are covered by the tolerances and specify 
how compliance with the tolerances is to be measured. The revised 
tolerance expression makes clear that the tolerances cover residues of 
the herbicide imazosulfuron, including its metabolites and degradates, 
but that compliance with the tolerance levels is to be determined by 
measuring only imazosulfuron, 2-chloro-N-[[(4,6-dimethoxy-2-
in or on the commodities.

 V. Conclusion

    Therefore, tolerances are established for residues of 
imazosulfuron, including its metabolites and degradates, in or on 
pepper, bell at 0.02 ppm; pepper, non-bell at 0.02 ppm; rice, grain at 
0.02 ppm; and tomato at 0.02 ppm. Compliance with the tolerance levels 
is to be determined by measuring only imazosulfuron, 2-chloro-N-[[(4,6-
sulfonamide, in or on the commodities.

VI. Statutory and Executive Order Reviews

    This final rule establishes tolerances under section 408(d) of 
FFDCA in response to a petition submitted to the Agency. The Office of 
Management and Budget (OMB) has exempted these types of actions from 
review under Executive Order 12866, entitled Regulatory Planning and 
Review (58 FR 51735, October 4, 1993). Because this final rule has been 
exempted from review under Executive Order 12866, this final rule is 
not subject to Executive Order 13211, entitled Actions Concerning 
Regulations That Significantly Affect Energy Supply, Distribution, or 
Use (66 FR 28355, May 22, 2001) or Executive Order 13045, entitled 
Protection of Children from Environmental Health Risks and Safety Risks 
(62 FR 19885, April 23, 1997). This final rule does not contain any 
information collections subject to OMB approval under the Paperwork 
Reduction Act (PRA), 44 U.S.C. 3501 et seq., nor does it require any 
special considerations under Executive Order 12898, entitled Federal 
Actions to Address Environmental Justice in Minority Populations and 
Low-Income Populations (59 FR 7629, February 16, 1994).
    Since tolerances and exemptions that are established on the basis 
of a petition under section 408(d) of FFDCA, such as the tolerance in 
this final rule, do not require the issuance of a proposed rule, the 
requirements of the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et 
seq.) do not apply.
    This final rule directly regulates growers, food processors, food 
handlers, and food retailers, not States or Tribes, nor does this 
action alter the relationships or distribution of power and 
responsibilities established by Congress in the preemption provisions 
of section 408(n)(4) of FFDCA. As such, the Agency has determined that 
this action will not have a substantial direct effect on States or 
Tribal governments, on the relationship between the national government 
and the States or Tribal governments, or on the distribution of power 
and responsibilities among the various levels of government or between 
the Federal Government and Indian Tribes. Thus, the Agency has 
determined that Executive Order 13132, entitled Federalism (64 FR 
43255, August 10, 1999) and Executive Order 13175, entitled 
Consultation and Coordination with Indian Tribal Governments (65 FR 
67249, November 9, 2000) do not apply to this final rule. In addition, 
this final rule does not impose any enforceable duty or contain any 
unfunded mandate as described under Title II of the Unfunded Mandates 
Reform Act of 1995 (UMRA) (Pub. L. 104-4).
    This action does not involve any technical standards that would 
require Agency consideration of voluntary consensus standards pursuant 
to section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272 

VII. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report to each House of the Congress and to 
the Comptroller General of the United States. EPA will submit a report 
containing this rule and other required information to the U.S. Senate, 
the U.S. House of Representatives, and the Comptroller General of the 
United States prior to publication of this final rule in the Federal 
Register. This final rule is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

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

    Dated: December 13, 2010.
Steven Bradbury,
Director, Office of Pesticide Programs.

Therefore, 40 CFR chapter I is amended as follows:


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

    Authority: 21 U.S.C. 321(q), 346a and 371.

2. Section 180.651 is added to read as follows:

Sec.  180.651  Imazosulfuron; tolerances for residues.

    (a) General. Tolerances are established for residues of the 
herbicide imazosulfuron, including its metabolites and degradates, in 
or on the following commodities. Compliance with the tolerance levels 
specified in the following table below is to be determined by measuring 
only imazosulfuron, 2-chloro-N-[[(4,6-dimethoxy-2-
in or on the commodity.

[[Page 81885]]

                                                              Parts per
                         Commodity                             million
Pepper, bell...............................................         0.02
Pepper, non-bell...........................................         0.02
Rice, grain................................................         0.02
Tomato.....................................................         0.02

     (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]
[FR Doc. 2010-32451 Filed 12-28-10; 8:45 am]