Document ID: EPA-HQ-OPP-2009-0325-0010
Agency: epa
Document Type: Rule
Title: Pesticide Tolerances: Hexythiazox
Posted Date: 2011-04-06T04:00Z

[Federal Register Volume 76, Number 66 (Wednesday, April 6, 2011)]
[Rules and Regulations]
[Pages 18895-18899]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-8182]

[[Page 18895]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2009-0325; FRL-8868-6]

Hexythiazox; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes tolerances for residues of 
hexythiazox in or on corn, sweet, kernel plus cob with husk removed; 
corn, sweet, forage; bean, dried; and bean, succulent. Gowan Company 
requested these tolerances under the Federal Food, Drug, and Cosmetic 
Act (FFDCA).

DATES: This regulation is effective April 6, 2011. Objections and 
requests for hearings must be received on or before June 6, 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).

ADDRESSES: EPA has established a docket for this action under docket 
identification (ID) number EPA-HQ-OPP-2009-0325. 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) 
305-5805.

FOR FURTHER INFORMATION CONTACT: Olga Odiott, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 308-9369; e-mail address: odiott.olga@epa.gov.

SUPPLEMENTARY INFORMATION:

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 
INFORMATION CONTACT.

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 eCFR 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-2009-0325 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 
June 6, 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-2009-0325, 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 August 19, 2009 (74 FR 41898) (FRL-8426-
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 
9F7549) by Gowan Company, 370 South Main Street, Yuma, AZ, 85364. The 
petition requested that 40 CFR 180.448 be amended by establishing 
tolerances for residues of the insecticide hexythiazox, trans-5-(4-
chlorophenyl)-N-cyclohexyl-4-methyl-2-oxothiazolidine-3-carboxamide and 
its metabolites containing the (4-chlorophenyl)-4-methyl-2-oxo-3-
thiazolidine moiety (expressed as parts per million of the parent 
compound), in or on corn, sweet, kernel plus cob with husk removed at 
0.1 parts per million (ppm); corn, sweet, forage at 3 ppm; bean, dried 
at 0.4 ppm; and bean, succulent at 0.4 ppm. That notice referenced a 
summary of the petition prepared by Gowan Company, the registrant, 
which is available in the docket, http://www.regulations.gov. There 
were no comments received in response to the notice of filing.
    Based upon review of the data supporting the petition, EPA has 
revised the proposed tolerance levels for corn, sweet, forage; and 
bean, succulent to 4 ppm and 0.3 ppm, respectively. The

[[Page 18896]]

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 sufficient data to assess the hazards of and to 
make a determination on aggregate exposure for hexythiazox including 
exposure resulting from the tolerances established by this action. 
EPA's assessment of exposures and risks associated with hexythiazox 
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 
children.
    Hexythiazox has low acute toxicity by the oral, dermal and 
inhalation routes of exposure. It produces mild eye irritation, is not 
a dermal irritant, and is negative for dermal sensitization. 
Hexythiazox is not a developmental or reproductive toxicant. The 
toxicology database for hexythiazox provides no indication of increased 
susceptibility in rats or rabbits from in utero and postnatal exposure 
to hexythiazox. The database does not show any evidence of treatment-
related effects on the nervous system or the immune system. Hexythiazox 
is classified as ``likely to be carcinogenic to humans''. EPA has 
determined that a non-quantitative risk assessment approach (i.e., 
nonlinear, reference dose (RfD) approach) was appropriate and 
protective of all chronic effects including potential carcinogenicity 
of hexythiazox.
    Specific information on the studies received and the nature of the 
adverse effects caused by hexythiazox 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 document ``Hexythiazox. Human Health Risk 
Assessment to Support New Uses on Sweet Corn, Dry Beans and Succulent 
Beans,'' page 24 in docket ID number EPA-HQ-OPP-2009-0325.

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 hexythiazox used for 
human risk assessment can be found in the final rule published in the 
Federal Register of March 17, 2010 (Vol. 75 FR 12691) (FRL-8813-7), and 
at http://www.regulations.gov in document ``Hexythiazox. Human Health 
Risk Assessment to Support New Uses on Sweet Corn, Dry Beans and 
Succulent Beans,'' page 11 in docket ID number EPA-HQ-OPP-2009-0325.

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. In evaluating dietary 
exposure to hexythiazox, EPA considered exposure under the petitioned-
for tolerances as well as all existing hexythiazox tolerances in 40 CFR 
180.448. EPA assessed dietary exposures from hexythiazox 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. No such effects were 
identified in the toxicological studies for hexythiazox; therefore, a 
quantitative acute dietary exposure assessment is unnecessary.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the food consumption data from the USDA 1994-1996 
and 1998 Nationwide Continuing Surveys of Food Intake by Individuals 
(CSFII). As to residue levels in food, EPA used tolerance level 
residues, assumed 100 percent crop treated (PCT), and incorporated DEEM 
default processing factors.
    iii. Cancer. EPA determines whether quantitative cancer exposure 
and risk assessments are appropriate for a food-use pesticide based on 
the weight of the evidence from cancer studies and other relevant data. 
Cancer risk is quantified using a linear or nonlinear approach. If 
sufficient information on the carcinogenic mode of action is available, 
a threshold or nonlinear approach is used and a cancer RfD is 
calculated based on an earlier noncancer key event. If carcinogenic 
mode of action data are not available, or if the mode of action data 
determines a mutagenic mode of action, a default linear cancer slope 
factor approach is utilized. Based on the data in the Federal Register 
of March 17, 2010 (Vol. 75 FR 12691) (FRL-8813-7), EPA has concluded 
that a nonlinear RfD approach is appropriate for assessing cancer risk 
to hexythiazox. Cancer risk was assessed using the same exposure 
estimates as discussed in Unit III.C.1.ii., chronic exposure.
    iv. Anticipated residue and percent crop treated (PCT) information. 
EPA did not use anticipated residue and/or PCT information in the 
dietary assessment for hexythiazox. Tolerance level residues and/or 100 
PCT were assumed for all food commodities.
    2. Dietary exposure from drinking water. The Agency used screening 
level

[[Page 18897]]

water exposure models in the dietary exposure analysis and risk 
assessment for hexythiazox in drinking water. These simulation models 
take into account data on the physical, chemical, and fate/transport 
characteristics of hexythiazox. Further information regarding EPA 
drinking water models used in pesticide exposure assessment can be 
found at http://www.epa.gov/oppefed1/models/water/index.htm.
    Based on the Pesticide Root Zone Model/Exposure Analysis Modeling 
System (PRZM/EXAMS), the estimated drinking water concentration (EDWC) 
of hexythiazox for chronic exposures for non-cancer and cancer 
assessments is estimated to be 4.5 ppb for surface water. Since surface 
water residue values greatly exceed groundwater EDWCs, surface water 
residues were used in the dietary risk assessment.
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model.
    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).
    Hexythiazox is not currently registered for any specific use 
patterns that would result in residential exposure. However, the 
following uses that could result in residential exposures are pending 
registration in the near future and are included in this risk 
assessment: Turf, ornamental landscape plantings, ornamental plants, 
trees and vines in nurseries, residential fruit trees, nut trees, 
caneberries, and orchids.
    Both adults and children may be exposed to hexythiazox residues 
from contact with treated lawns or treated plants. The exposure and 
risk assessment included risks to adult handlers from inhalation 
exposures. The exposure assessment for children included risks from 
incidental oral exposure resulting from transfer of residues from the 
hands or objects to the mouth, and from incidental ingestion of soil. 
Details of the residential exposure and risk assessment are contained 
in the final rule published in the Federal Register of July 14, 2010 
(75 FR 40741), and at http://www.regulations.gov in document 
``Hexythiazox. Human Health Risk Assessment to Support New Uses on 
Sweet Corn, Dry Beans, and Succulent Beans,'' page 16 in docket ID 
number EPA-HQ-OPP-2009-0325.
    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 hexythiazox to share a common mechanism of 
toxicity with any other substances, and hexythiazox does not appear to 
produce a toxic metabolite produced by other substances. For the 
purposes of this tolerance action, therefore, EPA has assumed that 
hexythiazox 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 
factor.
    2. Prenatal and postnatal sensitivity. The prenatal and postnatal 
toxicology data base indicates no increased susceptibility of rats or 
rabbits to in utero and/or postnatal exposure to hexythiazox.
    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 
findings:
    i. The toxicity database for hexythiazox is incomplete under the 
new 40 CFR part 158 data requirements for conventional pesticides, 
which requires certain generic testing, including acute and subchronic 
neurotoxicity studies and an immunotoxicity study. However, the 
toxicology database does not show any evidence of treatment-related 
effects on the nervous system or the immune system. The overall weight 
of evidence suggests that this chemical does not directly target either 
system. Although acute and subchronic neurotoxicity studies and an 
immunotoxicity study are required as a part of new data requirements in 
the 40 CFR part 158 for conventional pesticide registrations, the 
Agency does not believe that conducting these studies will result in a 
lower POD than any currently used for risk assessment, and therefore, a 
database uncertainty factor (UFDB) is not needed to account 
for the lack of these studies.
    ii. There is no indication that hexythiazox is a neurotoxic 
chemical and there is no need for a developmental neurotoxicity study 
or additional UFs to account for neurotoxicity.
    iii. There is no evidence that hexythiazox results in increased 
susceptibility in in utero rats or rabbits in the prenatal 
developmental studies or in young rats in the 2-generation reproduction 
study.
    iv. There are no residual uncertainties identified in the exposure 
databases. The dietary food exposure assessments were performed based 
on 100 PCT and tolerance-level residues. The dietary risk assessment is 
highly conservative and not expected to underestimate risk. EPA made 
conservative (protective) assumptions in the ground and surface water 
modeling used to assess exposure to hexythiazox 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 hexythiazox.

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. No adverse effect resulting from

[[Page 18898]]

a single oral exposure was identified and no acute dietary endpoint was 
selected. Therefore, hexythiazox is not expected to pose an acute risk.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that chronic exposure to 
hexythiazox from food and water will utilize 51% of the cPAD for 
children 1-2 years of age, 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 
hexythiazox 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).
    There are potential short-term exposures from the pending 
residential uses for hexythiazox. The Agency has determined that it is 
appropriate to aggregate chronic exposure through food and water with 
short-term residential exposures to hexythiazox.
    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 15,000 for adults 
and 1,900 for children. Because EPA's level of concern for hexythiazox 
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).
    There are potential intermediate-term exposures from the pending 
residential uses for hexythiazox. The Agency has determined that it is 
appropriate to aggregate chronic exposure through food and water with 
intermediate-term residential exposures to hexythiazox.
    Using the exposure assumptions described in this unit for 
intermediate-term exposures, EPA has concluded that the combined 
intermediate-term food, water, and residential exposures result in 
aggregate MOEs of 15,000 for adults and 2,200 for children. Because 
EPA's level of concern for Hexythiazox is a MOE of 100 or below, these 
MOEs are not of concern.
    5. Aggregate cancer risk for U.S. population. As discussed in Unit 
III.C.1.iii, EPA concluded that regulation based on the chronic 
reference dose will be protective for both chronic and carcinogenic 
risks. As noted in this unit there are no chronic risks of concern.
    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 hexythiazox residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (high performance liquid 
chromatography method with UV detection (HPLC/UV)) 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.

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.
    A Codex MRL for common beans (pods and/or immature seeds) is 
currently established at 0.5 ppm. It is not possible to harmonize the 
U.S. tolerance with the Codex MRL since the Codex MRL is for parent 
compound only and the U.S. expression includes metabolites of concern. 
There are no Canadian or Mexican MRLs for beans and there is no Codex, 
Canadian or Mexican MRL for sweet corn commodities.

C. Revisions to Petitioned for Tolerances

    Based upon review of the data supporting the petition, EPA has 
revised the proposed tolerance levels for corn, sweet, forage; and 
bean, succulent to 4 ppm and 0.3 ppm, respectively. The tolerance 
spreadsheet in the Agency's Guidance for Setting Pesticide Tolerances 
Based on Field Trial Data was used to determine appropriate tolerance 
levels for sweet corn forage, dried beans and succulent beans. The 
tolerance spreadsheet was not used for sweet corn kernel plus cob with 
husk removed (K+CWHR) because >65% of the residues were