

[Federal Register: May 31, 2006 (Volume 71, Number 104)]
[Rules and Regulations]               
[Page 30811-30818]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31my06-10]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2005-0215; FRL-8057-9]

 
Terbacil; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This regulation establishes a tolerance for combined residues 
of terbacil in or on watermelon. The Interregional Research Project 
Number 4 (IR-4), on behalf of the registrant, DuPont Crop Protection, 
requested this tolerance under the Federal Food, Drug, and Cosmetic Act 
(FFDCA), as amended by the Food Quality Protection Act of 1996 (FQPA). 
EPA is also deleting an existing time-limited terbacil tolerance that 
is no longer needed as a result of this action.

DATES:  This regulation is effective May 31, 2006. Objections and 
requests for hearings must be received on or before July 31, 2006, 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-2005-0215. All documents in the 
docket are listed in the index for the docket. Although listed in the 
index, some information is not publicly available, e.g., Confidential 
Business Information (CBI) or other information

[[Page 30812]]

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 
Building), 2777 S. Crystal Drive, Arlington, VA. The Docket Facility is 
open from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal 
holidays. The telephone number for the Docket Facility is (703) 305-
5805.

FOR FURTHER INFORMATION CONTACT: Sidney Jackson, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 305-7610; e-mail address: jackson.sidney@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:
     Crop production (NAICS 111), e.g., agricultural workers; 
greenhouse, nursery, and floriculture workers; farmers.
     Animal production (NAICS 112), e.g., cattle ranchers and 
farmers, dairy cattle farmers, livestock farmers.
     Food manufacturing (NAICS 311), e.g., agricultural 
workers; farmers; greenhouse, nursery, and floriculture workers; 
ranchers; pesticide applicators.
     Pesticide manufacturing (NAICS 32532), e.g., agricultural 
workers; commercial applicators; farmers; greenhouse, nursery, and 
floriculture workers; residential users.
    This listing is not intended to be exhaustive, but rather provides 
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 Access Electronic Copies of this Document?

    In addition to accessing an electronic copy of this Federal 
Register document through the electronic docket at http://www.regulations.gov
, you may access this Federal Register document 

electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr. You may also access a 

frequently updated electronic version of 40 CFR part 180 through the 
Government Printing Office's pilot e-CFR site at http://www.gpoaccess.gov/ecfr.
 To access the OPPTS Harmonized Guidelines 

referenced in this document, go directly to the guidelines at http://www.epa.gov/opptsfrs/home/guidelin.htm
.


C. Can I File an Objection or Hearing Request?

    Under section 408(g) of the FFDCA, as amended by the FQPA, any 
person may file an objection to any aspect of this regulation and may 
also request a hearing on those objections. The EPA procedural 
regulations which govern the submission of objections and requests for 
hearings appear in 40 CFR part 178. 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-2005-0215 in the 
subject line on the first page of your submission. All requests must be 
in writing, and must be mailed or delivered to the Hearing Clerk on or 
before July 31, 2006.
    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 that is described in ADDRESSES. Information not marked 
confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA 
without prior notice. Submit your copies, identified by docket ID 
number EPA-HQ-OPP-2005-0215, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 

Follow the on-line 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 
Building), 2777 S. Crystal Drive, Arlington, VA. Deliveries are only 
accepted during the Docket'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 
telephone number for the Docket Facility is (703) 305-5805.

II. Background and Statutory Findings

    In the Federal Register of September 7, 2005 (70 FR 53180) (FRL-
7731-1), 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 
3E6640) by IR-4, on behalf of DuPont Crop Protection, P.O. Box 30, 
Newark, Delaware 19714-0030. The petition requested that 40 CFR 180.209 
be amended by establishing a tolerance for combined residues of the 
herbicide terbacil, (3-tert-butyl-5-chloro-6-methyluracil) and its 
metabolites [3-tert-butyl-5-chloro-6-hydroxymethyluracil], [6-chloro-
2,3-dihydro-7-hydroxymethyl 3,3-dimethyl-5H-oxazolo(3,2-a) pyrimidin-5-
one], and [6-chloro-2,3-dihydro-3,3,7-trimethyl-5H-oxazolo(3,2-a) 
pyrimidin-5-one], in or on watermelon at 1.0 parts per million (ppm). 
That notice included a summary of the petition prepared by DuPont Crop 
Protection, the registrant. There were no comments received in response 
to the notice of filing.
    EPA is also deleting an established tolerance in section 40 CFR 
180.209(b) that is no longer needed, as a result of this action. The 
tolerance deletion under section 40 CFR 180.209(b) is a time-limited 
tolerance established under section 18 emergency exemptions that is 
superceded by the establishment of a general tolerance for terbacil 
section 40 CFR 180.209(a). The revision to 40 CFR 180.209 is as follow:
    Delete the time-limiting tolerance for watermelon at 0.4 ppm under 
40 CFR 180.209(b). Tolerance for watermelon at 1.0 ppm is established 
by this action under 40 CFR 180.209(a).
    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

[[Page 30813]]

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....''
    EPA performs a number of analyses to determine the risks from 
aggregate exposure to pesticide residues. For further discussion of the 
regulatory requirements of section 408 of the FFDCA and a complete 
description of the risk assessment process, see http://www.epa.gov/fedrgstr/EPA-PEST/
 1997/November/Day-26/p30948.htm.


III. Aggregate Risk Assessment and Determination of Safety

    Consistent with 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, consistent with section 
408(b)(2) of FFDCA, for a tolerance for combined residues of terbacil 
on watermelon at 1.0 ppm. EPA's assessment of exposures and risks 
associated with establishing the tolerance follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered their 
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. Specific information on the studies received and the nature 
of the toxic effects caused by terbacil as well as the no observed 
adverse effect level (NOAEL) and the lowest observed adverse effect 
level (LOAEL) from available toxicity studies as summarized in Table 1 
below:

 Table 1: Toxicity Profile for Terbacil -- Subchronic, Chronic and Other
                                Toxicity
------------------------------------------------------------------------
          Guideline No.               Study Type      Assessment Results
------------------------------------------------------------------------
870.3100                          90-Day oral         NOAEL = 500 ppm
                                   toxicity rat        (20 mg/kg/day)
                                  Dosage at 0, 8,     LOAEL = 5,000 ppm
                                   20, and 200         (200 mg/kg/day),
                                   milligrams/         based on focal
                                   kilogram/day (mg/   necrosis and
                                   kg/day).            triaditis in
                                                       females (F),
                                                       vacuolization in
                                                       males (M) and
                                                       increased
                                                       relative liver
                                                       weight and
                                                       hypertrophy of
                                                       hepatocytes in
                                                       both sexes.
------------------------------------------------------------------------
870.3200                          21-Day dermal       NOAEL = 5,000 mg/
                                   rabbit              kg/day
                                  Dosage at 0 and     LOAEL was not
                                   5,000 mg/kg/day.    established.
                                                       There were no
                                                       clinical signs of
                                                       toxicity, gross
                                                       or
                                                       histopathologic
                                                       changes.
------------------------------------------------------------------------
870.4100                          Chronic oral 2-     NOAEL = 250 ppm
                                   year dog            (equivalent to
                                  Dosage at 0, 1.0,    5.0 mg/kg/day)
                                   5.0, 50, and 200   LOAEL = 2500 ppm
                                   mg/kg/day.          (equivalent to 50
                                                       mg/kg/day), based
                                                       on increased
                                                       relative thyroid
                                                       weights and
                                                       thymic involution
                                                       in both sexes.
------------------------------------------------------------------------
870.4200                          Carcinogenicity     NOAEL = 162 mg/kg/
                                   mouse               day
                                  Dosage for M/F: 0/  LOAEL = 746 mg/kg/
                                   0, 6.5/8.0, 162/    day, based on
                                   199, and 746/895    increased liver
                                   mg/kg/day.          weights,
                                                       hyperplastic
                                                       nodules,
                                                       necrosis, and
                                                       vacuolation in
                                                       the liver in
                                                       males.
                                                      There was no
                                                       oncogenic
                                                       potential at the
                                                       doses tested.
------------------------------------------------------------------------
870.3700                          Developmental       Maternal NOAEL was
                                   toxicity rat        not established
                                  Dosage at 0, 24,    Maternal LOAEL =
                                   104 and 392 mg/kg/  24 mg/kg/day
                                   day.                based on
                                                       decreased body
                                                       weight gain.
                                                      Developmental
                                                       NOAEL = 24 mg/kg/
                                                       day
                                                      Developmental
                                                       LOAEL = 104 mg/kg/
                                                       day, based on
                                                       decreased number
                                                       of live fetuses/
                                                       litter.
------------------------------------------------------------------------
870.3700                          Developmental       Maternal NOAEL =
                                   Toxicity rabbit     200 mg/kg/day
                                  Dosage at 0, 30,    Maternal LOAEL =
                                   200, and 600 mg/    600 mg/kg/day,
                                   kg/day.             based on
                                                       mortality,
                                                       clinical findings
                                                       (anorexia,
                                                       discharge),
                                                       decreased body
                                                       weight and body
                                                       weight gain.
                                                      Developmental
                                                       NOAEL = 200 mg/kg/
                                                       day
                                                      Developmental
                                                       LOAEL = 600 mg/kg/
                                                       day, based on
                                                       decreased body
                                                       weight, increased
                                                       incidence of
                                                       skeletal
                                                       malformations
                                                       (fused ribs) and
                                                       increase
                                                       frequency of
                                                       skeletal
                                                       variations.
------------------------------------------------------------------------

[[Page 30814]]


870.3800                          3-generation        Parental NOAEL =
                                   reproduction -      50 ppm
                                   rat                 (equivalent to2.0
                                  Dosage at 0, 2.0,    mg/kg/day)
                                   and 10 mg/kg/day.  Parental LOAEL =
                                                       250 ppm
                                                       (equivalent to 10
                                                       mg/kg/day) based
                                                       on decreased body
                                                       weight,
                                                      Reproductive NOAEL
                                                       = 250 ppm
                                                       (equivalent to 10
                                                       mg/kg/day)
                                                      Reproductive LOAEL
                                                       was not
                                                       established
                                                       Offspring NOAEL =
                                                       250 ppm
                                                       (equivalent to 10
                                                       mg/kg/day)
                                                      Offspring LOAEL
                                                       was not
                                                       established
------------------------------------------------------------------------
870.4300                          Combined Chronic    NOAEL (M/F)= 58/
                                   Toxicity/           1.4 mg/kg/day
                                   Carcinogenicity    LOAEL (M/F)= 308/
                                   rat                 83 mg/kg/day,
                                  Dosage M/F: 0/0,     based on
                                   0.9/1.4, 58/83,     decreased body
                                   308/484 mg/kg/day.  weight and body
                                                       weight gain and
                                                       increased
                                                       absolute and
                                                       relative liver
                                                       weights in males
                                                       and females.
                                                       There was no
                                                       oncogenic
                                                       potential at the
                                                       doses tested.
------------------------------------------------------------------------
870.4300                          Combined Chronic    Systemic NOAEL =
                                   Toxicity/           250 ppm
                                   Carcinogenicity     (equivalent to 10
                                   rat                 mg/kg/day)
                                  Dosage at 0, 2.0,   Systemic LOAEL =
                                   10 and 100/400 mg/  2,500/10,000 ppm
                                   kg/day).            (equivalent to
                                                       100/400 mg/kg/
                                                       day) based on
                                                       increased mean
                                                       relative liver
                                                       weights,
                                                       hepatocyte
                                                       centrilobular
                                                       hypertrophy in
                                                       males and females
                                                       and vacuolation
                                                       in females. There
                                                       was no oncogenic
                                                       potential at the
                                                       doses tested.
------------------------------------------------------------------------
870.5300                          Mutagenic- (HGPRT)  Did not induce
                                  Dosage at 0, 2, 3,   mutation in
                                   5 and 6 mM (-S9);   chinese hamster
                                   0, 1, 2, 2.5,       ovary cells with
                                   2.75, 3.25 and      or without
                                   3.50 mM (+S9).      metabolic
                                                       activation.
------------------------------------------------------------------------
870.5375                          In vitro            Negative for
                                   chromosome          clastogenic
                                   aberration assay    activity in the
                                   CHO cells           rat bone marrow
                                  Dosage at 0, 20,     cytogenetic
                                   100 and 500 mg/kg.  assay.
------------------------------------------------------------------------
870.5500                          Unscheduled DNA     Did not induce
                                   synthesis assay     unscheduled DNA
                                   rat primary         synthesis in
                                   hepatocyte          primary rat
                                  Dosage at 0,         hepatocytes.
                                   0.010, 0.033,
                                   0.10, 0.33, 1.0,
                                   2.5, 5.0, 7.5,
                                   and 10 mM.
------------------------------------------------------------------------
870.5100                           Mutagenicity       Did not show the
                                   study               suspected (5-
                                   (bacteriophage      bromo-uracil
                                   assay)              metabolite)
                                                       mutagenic action.
------------------------------------------------------------------------
870.7485                          Metabolism study    Approximately 57-
                                   rat                 82% of the
                                  Doseage at single    administered dose
                                   doses of 6.5 or     was absorbed in
                                   500 mg/kg.          24 hours. Ninety
                                                       one to 103% of
                                                       radioactivity was
                                                       recovered within
                                                       5 days; with 70
                                                       to 86% in urine
                                                       and 14-28% in
                                                       feces. The major
                                                       metabolites were
                                                       glucuronide,
                                                       sulfate and
                                                       sulfate/N-
                                                       acetylcysteine
                                                       conjugates. The
                                                       primary metabolic
                                                       pathway is
                                                       hydroxylation of
                                                       the 6-methyl
                                                       group to form the
                                                       alcohol which is
                                                       conjugated to
                                                       form the
                                                       glucuronide (35%
                                                       of the dose) and
                                                       the sulfate
                                                       derivatives
                                                       (11%). Terbacil
                                                       is also
                                                       metabolized to
                                                       the 5-hydroxy
                                                       intermediate,
                                                       which is further
                                                       conjugated to
                                                       form a sulfate
                                                       derivative (17%).
                                                       There was no
                                                       evidence
                                                       suggestive of
                                                       bioaccumulation.
------------------------------------------------------------------------

B. Toxicological Endpoints

    For hazards that have a threshold below which there is no 
appreciable risk, the dose at which the NOAEL from the toxicology study 
identified as appropriate for use in risk assessment is used to 
estimate the toxicological level of concern (LOC). However, the LOAEL 
is sometimes used for risk assessment if no NOAEL was achieved in the 
toxicology study selected. An uncertainty factor (UF) is applied to 
reflect uncertainties inherent in the extrapolation from laboratory 
animal data to humans and in the variations in sensitivity among 
members of the human population as well as other unknowns.
    The linear default risk methodology (Q*) is the primary method 
currently used by the Agency to quantify non-threshold hazards such as 
cancer. The Q* approach assumes that any amount of exposure will lead 
to some degree of cancer risk, estimates risk in terms of the 
probability of occurrence of additional cancer cases. More information 
can be found on the general principles EPA uses in risk

[[Page 30815]]

characterization at http://www.epa.gov/pesticide/health/human.htm.

    A summary of the toxicological endpoints for terbacil used for 
human risk assessment is presented in the following Table 2:

       Table 2.--Summary of Toxicological Dose and Endpoints for terbacil for Use in Human Risk Assessment
----------------------------------------------------------------------------------------------------------------
                                          Dose Used in Risk
                                             Assessment,          Special FQPA SF and
          Exposure/Scenario                Interspecies and       Level of Concern for   Study and Toxicological
                                         Intraspecies and any       Risk Assessment              Effects
                                            Traditional UF
----------------------------------------------------------------------------------------------------------------
Acute Dietary                          NA                       NA                       An endpoint of concern
(General Population and Females 13-50                                                     attributable to a
 years of age).                                                                           single dose for the
                                                                                          general population or
                                                                                          female 13+ was not
                                                                                          identified
----------------------------------------------------------------------------------------------------------------
Chronic dietary (All populations)      NOAEL= 1.4 mg/kg/day     Special FQPA SF = 1X     Combined Chronic
                                       UF = 100X..............  cPAD = cRfD divided by.   Toxicity/
                                       Chronic RfD = cRfD=      Special FQPA SF........   carcinogenicity - rat
                                        0.014 mg/kg/day.         = 0.014 mg/kg/day.....  LOAEL = 83 mg/kg/day
                                                                                          based on decreased
                                                                                          body weight and body
                                                                                          weight gain in females
----------------------------------------------------------------------------------------------------------------
Short (1-30 days) and Intermediate (1- Oral NOAEL = 2.0 mg/kg/  LOC for margin of        3-Generation
 6 months) Term Incidental oral         day (inhalation          exposure (MOEs) < 100     reproduction - rat
                                        absorption rate = 100%   (occupational and       LOAEL = 10 mg/kg/day
                                        oral equivalent)         residential)             based on decreased
                                                                                          body weight
----------------------------------------------------------------------------------------------------------------
Dermal (any time period)               NA                       NA                       Quantification of
                                                                                          dermal risk is not
                                                                                          required; the lack of
                                                                                          dermal or systemic
                                                                                          toxicity at 5,000 mg/
                                                                                          kg (5X the limit dose)
                                                                                          in a 21 day dermal
                                                                                          toxicity study in rats
                                                                                          which indicates poor
                                                                                          dermal absorption.
----------------------------------------------------------------------------------------------------------------
Short- (1 to 30 days) and              NOAEL= 2.0 mg/kg/day     LOC for MOEs < 100        3-Generation
 Intermediate- (1 to 6 months) term     (inhalation absorption   (residential)            reproduction - rat
 inhalation                             rate = 100% oral                                 LOAEL = 10 mg/kg/day,
                                        equivalent)                                       based on decreased
                                                                                          body weight
----------------------------------------------------------------------------------------------------------------
Long-term inhalation (> 6 months)      Oral NOAEL= 1.4 mg/kg/   LOC for MOE <100         Combined Chronic
                                        day (inhalation          (residential and         Toxicity/Carcinogeni-
                                        absorption rate = 100%   occupational)            city - rat
                                        oral equivalent)                                 LOAEL = 83 mg/kg/day
                                                                                          based on decreased
                                                                                          body weight and body
                                                                                          weight gain in females
----------------------------------------------------------------------------------------------------------------
Cancer (oral, dermal, inhalation)      NA                       NA                       Classification: Not
                                                                                          likely to be
                                                                                          carcinogenic to humans
----------------------------------------------------------------------------------------------------------------

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. Tolerances have been 
established (40 CFR 180.209) for the combined residues of terbacil, in 
or on a variety of raw agricultural commodities. Tolerances are 
currently established for the combined residues of terbacil, (3-tert-
butyl-5-chloro-6-methyluracil) and its metabolites [3-tert-butyl-5-
chloro-6-hydroxymethyluracil], [6-chloro-2,3-dihydro-7-hydroxymethyl 
3,3-dimethyl-5H-oxazolo(3,2-a) pyrimidin-5-one], and [6-chloro-2,3-
dihydro-3,3,7-trimethyl-5H-oxazolo(3,2-a) pyrimidin-5-one], calculated 
as terbacil, in/on alfalfa, apple, asparagus, blueberry, caneberry, 
peach, peppermint, spearmint, strawberry, and sugarcane ranging from 
0.1-2.0 ppm. A time-limited tolerance at 0.4 ppm in/on watermelon is 
currently established under section 18 exemption of the FIFRA and 
scheduled to expire June 30, 2007. Tolerances in/on livestock are not 
currently established. There are no feed commodities associated with 
watermelon.
    Risk assessments were conducted by EPA to assess dietary exposures 
from terbacil 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.
    An appropriate endpoint attributable to a single dose for the 
general population or females 13 years and older was not identified in 
the toxicological studies for terbacil; therefore, a quantitative acute 
dietary exposure assessment is not needed.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the Dietary Exposure Evaluation Model software with 
the Food Commodity Intake Database (DEEM-FCID\TM\ ver. 2.3), which 
incorporates food consumption data as reported by respondents in the 
U.S. Department of Agriculture (USDA) 1994-1996 and 1998 nationwide 
Continuing Surveys of Food Intake by Individuals (CSFII), and 
accumulated exposure to the chemical for each commodity. The following 
assumptions were made for the chronic exposure assessments: The chronic 
dietary analysis incorporated tolerance level residues, 100% crop 
treated, and DEEM\TM\ (ver 7.81) default processing factors for all 
registered/proposed crops. The chronic analysis also assumed the 
Screening Concentration in Ground Water (SCI-GROW) modeled water 
estimates for all water sources (direct and indirect). The ground water 
estimate was generated using the highest registered/proposed 
application rate. Although rotational crop tolerances are not currently 
established, the Agency concluded that the dietary analysis should 
incorporate residue estimates for rotated crops. Of the registered/
proposed crops, alfalfa, mint, strawberry, sugar cane, and watermelon 
are crops which are rotated. Based on the field rotational crop data 
(residues < 

[[Page 30816]]

= 0.19 ppm, 0.3-2.1 x the maximum application rate, 30-day plant-back 
intervals (PBIs)), the registered proposed PBIs, and the application 
rates, residues in/on crops rotated into alfalfa, mint, and sugar cane 
fields which were treated with terbacil are possible. Based on the 
field rotational crop data, the dietary analysis assumed a residue of 
1.0 ppm for cereal grains and soybean (these crops are commonly rotated 
into alfalfa, mint, and sugarcane fields) Based on the tolerances for 
the primary crops (0.1-2.0 ppm) and the field rotational crop data, EPA 
anticipates that the 1.0 ppm residue for rotated crops is conservative.
    The Agency notes that the assessment assumes, based on cultural 
practices, that only cereal grains and soybean are rotated into 
alfalfa, sugar cane, and mint fields while the registered application 
scenario for these crops permits the rotation of any crop. When the 
residue estimates used to generate the dietary exposure estimates are 
taken in total ((SCI-GROW) drinking water estimates, tolerance level 
residue, 100% crop treated for all registered/proposed crops, 
conservative residue estimates for cereal grain and soybean rotation 
crops), EPA concludes that chronic dietary exposure to terbacil is 
likely to be less than the estimates provided in this document.
    iii. Cancer. Terbacil is classified as not likely to be 
carcinogenic to humans based on the lack of evidence of carcinogenicity 
in a carcinogenicity study in mice and two combined chronic toxicity/
carcinogenicity studies in rats. Therefore, a cancer exposure 
assessment was not performed.
    2. Dietary exposure from drinking water. The Agency lacks 
sufficient monitoring exposure data to complete a comprehensive dietary 
exposure analysis and risk assessment for terbacil in drinking water. 
Because the Agency does not have comprehensive monitoring data, 
drinking water concentration estimates are made by reliance on 
simulation or modeling taking into account data on the physical 
characteristics of terbacil. 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) and SCI-GROW models, the estimated environmental 
concentrations (EECs) of terbacil for acute exposures are estimated to 
be 123 parts per billion (ppb) for surface water and 111 ppb for ground 
water. The EECs for chronic exposures are estimated to be 25.4 ppb for 
surface water and 111 ppb for ground water.
    The drinking water estimates are based upon the crop with the 
highest application rate (sugarcane). The use of terbacil on sugarcane 
has the highest single application rate at 3.0 pounds active 
ingredient/acre (lb ai/A), this application rate was used in the PRZM/
EXAMS and SCI-GROW models to estimate the concentrations of this 
chemical in surface water and ground water, respectively.
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model (DEEM\TM\ - FCID). For chronic 
dietary risk assessment, the annual average concentration of 111 ppb 
was used to access 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).
    Terbacil is not registered for use on any sites that would result 
in residential exposure.
    4. Cumulative effects from substances with a common mechanism of 
toxicity. Section 408(b)(2)(D)(v) of the 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.''
    Unlike other pesticides for which EPA has followed a cumulative 
risk approach based on a common mechanism of toxicity, EPA has not made 
a common mechanism of toxicity finding as to terbacil and any other 
substances and terbacil does not appear to produce a toxic metabolite 
produced by other substances. For the purposes of this tolerance 
action, therefore, EPA has not assumed that terbacil has 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 
the policy statements released by EPA's Office of Pesticide Programs 
concerning common mechanism determinations and procedures for 
cumulating effects from substances found to have a common mechanism on 
EPA's website at http://www.epa.gov/pesticides/cumulative.


D. Safety Factor for Infants and Children

    1. In general. Section 408 of FFDCA provides that EPA shall apply 
an additional tenfold 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. Margins of safety are 
incorporated into EPA risk assessments either directly through use of a 
MOE analysis or through using uncertainty (safety) factors in 
calculating a dose level that poses no appreciable risk to humans. In 
applying this provision, EPA either retains the default value of 10X 
when reliable data do not support the choice of a different factor, or, 
if reliable data are available, EPA uses a different additional safety 
factor value based on the use of traditional uncertainty factors and/or 
special FQPA safety factors, as appropriate.
    2. Prenatal and postnatal sensitivity. There is no indication of 
increased susceptibility of rat and rabbit fetuses to in utero and/or 
postnatal exposure to terbacil.
    3. Conclusion. There is a complete toxicity database for terbacil 
and exposure data are complete or are estimated based on data that 
reasonably account for potential exposures. Based on analyses of 
available exposure data, as outlined in Unit III.C.1.ii., the Agency 
believes that exposure to terbacil from existing and potential sources 
has been adequately assessed and is likely to be less than the 
estimates provided. EPA concludes that the FQPA SF can be reduced to 1x 
for the following reasons: (i) There is no evidence of increased 
susceptibility in rat and rabbit fetuses to in utero exposure to 
terbacil; (ii) there is no evidence of increased susceptibility to 
terbacil following prenatal exposure in a 3-generation reproduction 
study in rats; (iii) there are no residual toxicological uncertainties 
or concerns for increased susceptibility; (iv) there are well 
established NOAELs and LOAELs in the developmental and reproduction 
studies; (v) the environmental fate database is adequate to access the 
nature and magnitude of the residue in drinking water; (vi) the dietary 
exposure analysis assumed tolerance-level residues and 100% crop 
treated.

E. Aggregate Risks and Determination of Safety

    The Agency currently has two ways to estimate total aggregate 
exposure to a

[[Page 30817]]

pesticide from food, drinking water, and residential uses. First, a 
screening assessment can be used, in which the Agency calculates 
drinking water levels of comparison (DWLOCs) which are used as a point 
of comparison against estimated drinking water concentrations (EDWCs). 
The DWLOC values are not regulatory standards for drinking water, but 
are theoretical upper limits on a pesticide's concentration in drinking 
water in light of total aggregate exposure to a pesticide in food and 
residential uses. More information on the use of DWLOCs in dietary 
aggregate risk assessments can be found at http://www.epa.gov/oppfead1/trac/science/screeningsop.pdf
.

    More recently the Agency has used another approach to estimate 
aggregate exposure through food, residential and drinking water 
pathways. In this approach, modeled surface water and ground water 
EDWCs are directly incorporated into the dietary exposure analysis, 
along with food. This provides a more realistic estimate of exposure 
because actual body weights and water consumption from the CSFII are 
used. The combined food and water exposures are then added to estimated 
exposure from residential sources to calculate aggregate risks. The 
resulting exposure and risk estimates are still considered to be high 
end, due to the assumptions used in developing drinking water modeling 
inputs.
    1.  Acute risk. An endpoint of concern attributable to a single 
exposure was not identified in the hazard database and therefore no 
acute risk is expected from exposure to terbacil.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that exposure to terbacil 
from food and water will utilize 40% of the cPAD for the U.S. 
population, 99% of the cPAD for all infants < 1 year old (subpopulations 
at greatest exposure), and 94% of the cPAD for children 1-2 years old. 
There are no residential uses for terbacil that result in chronic 
residential exposure to terbacil. Based on the use pattern, chronic 
residential exposure to residues of terbacil is not expected since 
there are no registered residential use. The Agency believes that 
exposure to terbacil from existing and potential sources has been 
adequately assessed and that chronic exposure to terbacil is likely to 
be less than the estimates provided in this document as discussed in 
Unit III.C.1.ii.
    3. Short-term and Intermediate-term risk. Short-term and 
intermediate-term aggregate exposure takes into account residential 
exposure plus chronic exposure to food and water (considered to be a 
background exposure level). Terbacil is not registered for use on any 
sites that would result in residential exposure. Therefore, the 
aggregate risk is the sum of the risk from food and water, which do not 
exceed the Agency's level of concern.
    4. Aggregate cancer risk for U.S. population. Terbacil has been 
classified as ``not likely to be carcinogenic to humans'' based on the 
results of a carcinogenicity study in mice and the combined chronic 
toxicity and carcinogenicity study in rats. Therefore, terbacil is not 
expected to pose a cancer risk to humans.
    5. 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, and to infants and children from aggregate 
exposure to terbacil residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    There is a practical analytical method gas chromatography/electron 
capture detection (GC/ELCD) for detecting and measuring levels of 
terbacil in or on food with residues at or above the level set by the 
terbacil tolerance(Method II of PAM Vol. II). EPA has provided 
information on this method to the Food and Drug Administration (FDA). 
The method is available to anyone who is interested and 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

    There are no Codex, Canadian, or Mexican maximum residue limits in 
or on watermelon.

C. Conditions of Registration

    Data gaps exist as follow and are required to be satisfactorily 
filled as conditions of registration for this use.
    1. Petition Method Validation (PMV) of the plant method(s).
    2. FDA multiresidue testing of terbacil and its metabolites through 
protocol D.
     3. Additional watermelon field trial, conducted with application 
after crop emergence, in Region 3 (n=1), 5 (n=1), and 6 (n=1).

V. Conclusion

    Therefore, tolerance is established for combined residues of the 
herbicide, terbacil (3-tert-butyl-5-chloro-6-methyluracil) and its 
metabolites [3-tert-butyl-5-chloro-6-hydroxymethyluracil], [6-chloro-
2,3-dihydro-7-hydroxymethyl 3,3-dimethyl-5H-oxazolo(3,2-a) pyrimidin-5-
one], and [6-chloro-2,3-dihydro-3,3,7-trimethyl-5H-oxazolo(3,2-a) 
pyrimidin-5-one], calculated as terbacil, in or on watermelon at 1.0 
ppm.

VI. Statutory and Executive Order Reviews

    This final rule establishes a tolerance 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 rule has been 
exempted from review under Executive Order 12866 due to its lack of 
significance, this rule is not subject to Executive Order 13211, 
Actions Concerning Regulations That Significantly Affect Energy Supply, 
Distribution, or Use (66 FR 28355, May 22, 2001). 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., or impose 
any enforceable duty or contain any unfunded mandate as described under 
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA) (Public Law 
104-4). 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); or OMB review or any Agency action under Executive 
Order 13045, entitled Protection of Children from Environmental Health 
Risks and Safety Risks (62 FR 19885, April 23, 1997). 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 note). 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. In addition, the Agency has determined that this 
action will not have a substantial direct effect on States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government, as specified in Executive Order 13132, entitled Federalism 
(64 FR 43255, August 10,

[[Page 30818]]

1999). Executive Order 13132 requires EPA to develop an accountable 
process to ensure ``meaningful and timely input by State and local 
officials in the development of regulatory policies that have 
federalism implications.'' ``Policies that have federalism 
implications'' is defined in the Executive order to include regulations 
that have ``substantial direct effects on the States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.'' This final rule directly regulates growers, food 
processors, food handlers and food retailers, not States. This action 
does not alter the relationships or distribution of power and 
responsibilities established by Congress in the preemption provisions 
of section 408(n)(4) of FFDCA. For these same reasons, the Agency has 
determined that this rule does not have any ``tribal implications'' as 
described in Executive Order 13175, entitled Consultation and 
Coordination with Indian Tribal Governments (65 FR 67249, November 6, 
2000). Executive Order 13175, requires EPA to develop an accountable 
process to ensure ``meaningful and timely input by tribal officials in 
the development of regulatory policies that have tribal implications.'' 
``Policies that have tribal implications'' is defined in the Executive 
order to include regulations that have ``substantial direct effects on 
one or more Indian tribes, on the relationship between the Federal 
Government and the Indian tribes, or on the distribution of power and 
responsibilities between the Federal Government and Indian tribes.'' 
This rule will not have substantial direct effects on tribal 
governments, on the relationship between the Federal Government and 
Indian tribes, or on the distribution of power and responsibilities 
between the Federal Government and Indian tribes, as specified in 
Executive Order 13175. Thus, Executive Order 13175 does not apply to 
this rule.

VII. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
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.

    May 16, 2006.
Lois Rossi,
Director, Registration Division, Office of Pesticide Programs.

0
Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

0
1. The authority citation for part 180 continues to read as follows:

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

0
2. Section 180.209 is revised to read as follows:


Sec.  180.209   Terbacil; tolerances for residues.

    (a) General. Tolerances are established for combined residues of 
the herbicide terbacil, (3-tert-butyl-5-chloro-6-methyluracil) and its 
metabolites [3-tert-butyl-5-chloro-6-hydroxymethyluracil], [6-chloro-
2,3-dihydro-7-hydroxymethyl 3,3-dimethyl-5H-oxazolo(3,2-a) pyrimidin-5-
one], and [6-chloro-2,3-dihydro-3,3,7-trimethyl-5H-oxazolo(3,2-a) 
pyrimidin-5-one], calculated as terbacil, in or on the following raw 
agricultural commodities:

------------------------------------------------------------------------
                      Commodity                        Parts per million
------------------------------------------------------------------------
Alfalfa, forage......................................                1.0
Alfalfa, hay.........................................                2.0
Apple................................................                0.3
Asparagus............................................                0.4
Blueberry............................................                0.2
Canebserry...........................................                0.2
Peach................................................                0.2
Peppermint, tops.....................................                2.0
Spearmint, tops......................................                2.0
Strawberry...........................................                0.1
Sugarcane, cane......................................                0.4
Watermelon...........................................                1.0
------------------------------------------------------------------------

    (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]
[FR Doc. E6-8275 Filed 5-30-06; 8:45 am]

BILLING CODE 6560-50-S
