[Federal Register Volume 66, Number 120 (Thursday, June 21, 2001)]
[Rules and Regulations]
[Pages 33187-33195]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-15614]


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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-301138; FRL-6787-7]
RIN 2070-AB78


Mesotrione; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

SUMMARY: This regulation establishes a tolerance for residues 
ofmesotrione, 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-
cyclohexanedione, in or on field corn. Syngenta Crop Protection Inc. 
requested this tolerance under the Federal Food, Drug, and Cosmetic 
Act, as amended by the Food Quality Protection Act of 1996.

DATES: This regulation is effective June 21, 2001. Objections and 
requests for hearings, identified by docket control number OPP-301138, 
must be received by EPA on or before August 20, 2001.

ADDRESSES: Written objections and hearing requests may be submitted by 
mail, in person, or by courier. Please follow the detailed instructions 
for each method as provided in Unit VI. of the SUPPLEMENTARY 
INFORMATION. To ensure proper receipt by EPA, your objections and 
hearing requests must identify docket control numberOPP-301138 in the 
subject line on the first page of your response.

FOR FURTHER INFORMATION CONTACT: By mail: Joanne Miller,Registration 
Division (7505C), Office of Pesticide Programs, Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW.,Washington, DC 20460; 
telephone number: 703-305-6224; and e-mail address: 
[email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    You may be affected by this action if you are an agricultural 
producer, food manufacturer, or pesticide manufacturer. Potentially 
affected categories and entities may include, but are not limited to:

------------------------------------------------------------------------
                                                 Examples of Potentially
             Categories                 NAICS       Affected Entities
------------------------------------------------------------------------
Industry                                    111  Crop production
                                            112  Animal production
                                            311  Food manufacturing
                                          32532  Pesticide manufacturing
------------------------------------------------------------------------


[[Page 33188]]

    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 the table could also be 
affected. The North American Industrial Classification System (NAICS) 
codes have been provided to assist you and others in determining 
whether or not this action might apply t certain entities. If you have 
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 Additional Information, Including Copies of this 
Document and Other Related Documents?

    1. Electronically.You may obtain electronic copies of this 
document, and certain other related documents that might be available 
electronically, from the EPA Internet Home Page at http://www.epa.gov/. 
To access this document, on the Home Page select ``Laws and 
Regulations'', ``Regulations and Proposed Rules,'' and then look up the 
entry for this document under the ``Federal Register---Environmental 
Documents.'' You can also go directly to the Federal Register listings 
at http://www.epa.gov/fedrgstr/. To access the OPPTS Harmonized 
Guidelines referenced in this document, go directly to the guidelines 
at http://www.epa.gov/opptsfrs/home/guidelin.htm. A frequently updated 
electronic version of 40 CFR part 180 is available at http://www.access.gpo.gov/nara/cfr/cfrhtml_180/Title_40/40cfr180_00. html, a 
beta site currently under development.
    2. In person. The Agency has established an official record for 
this action under docket control number OPP-301138. The official record 
consists of the documents specifically referenced in this action, and 
other information related to this action, including any information 
claimed as Confidential Business Information (CBI). This official 
record includes the documents that are physically located in the 
docket, as well as the documents that are referenced in those 
documents. The public version of the official record does not include 
any information claimed as CBI. The public version of the official 
record, which includes printed, paper versions of any electronic 
comments submitted during an applicable comment period is available for 
inspection in the Public Information and Records Integrity Branch 
(PIRIB), Rm. 119, Crystal Mall #2, 1921 Jefferson Davis Hwy., 
Arlington, VA, from 8:30 a.m. to 4 p.m., Monday through Friday, 
excluding legal holidays. The PIRIB telephone number is (703) 305-5805.

II. Background and Statutory Findings

    In the Federal Register of May 29, 1998 (63 FR 29401) (FRL-5791-2), 
EPA issued a notice pursuant to section 408 of the Federal Food, Drug, 
and Cosmetic Act (FFDCA), 21 U.S.C. 346a as amended by the Food Quality 
Protection Act of 1996 (FQPA) (Public Law 104-170) announcing the 
filing of a pesticide petition (PP 8F4954) for tolerance by Zeneca Ag 
Products, 1800 Concord Pike, Wilmington, DE 19850-5458. This notice 
included a summary of the petition prepared by Zeneca Ag Products, the 
registrant. There were no comments received in response to the notice 
of filing. The petition was subsequently transferred to Syngenta Crop 
Protection Inc., 410 Swing Road, PO Box 18300, Greensboro, NC 27419-
8300
    The petition requested that 40 CFR part 180 be amended by 
establishing a tolerance for residues of the herbicide 2-[4-
(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione, in or on the raw 
agricultural commodities field corn, field corn fodder and field corn 
forage at 0.01 part per million (ppm). EPA is editorially correcting 
the tolerances expression to read: field corn grain, field corn forage 
and field corn stover at 0.01 ppm.
    Section 408(b)(2)(A)(i) of the 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) 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) 
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....''
    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 and a complete description of 
the risk assessment process, see the final rule on Bifenthrin Pesticide 
Tolerances (62 FR 62961, November 26, 1997) (FRL-5754-7).

III. Aggregate Risk Assessment and Determination of Safety

    Consistent with section 408(b)(2)(D), 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), for a tolerance for residues of mesotrione, 2-[4-
(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione, in or on field 
corn grain, field corn forage and field corn stover at 0.01 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 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. The nature of the toxic effects caused by mesotrione are 
discussed in the following Table 1 as well as the no observed adverse 
effect level (NOAEL) and the lowest observed adverse effect level 
(LOAEL) from the toxicity studies reviewed.

                                Table 1.--Subchronic, Chronic, and Other Toxicity
----------------------------------------------------------------------------------------------------------------
             Guideline No.                       Study Type                            Results
----------------------------------------------------------------------------------------------------------------
870.3100                                 90-Day oral toxicity        NOAEL = 0.41/0.47 milligram (mg)/kilogram
                                          rodents (rat)               (kg)/day (males [M]/females [F])
                                                                     LOAEL = 0.63/0.71 mg/kg/day (M/F), based
                                                                      upon corneal lesion in males
----------------------------------------------------------------------------------------------------------------

[[Page 33189]]

 
870.3100                                 90-Day oral toxicity        NOAEL = 0.09/0.10 mg/kg/day (M/F)
                                          rodents (rat)
                                                                     LOAEL = 11/13 mg/kg/day (M/F), based upon
                                                                      corneal abnormalities in both sexes and
                                                                      decreased body weight gain in males
----------------------------------------------------------------------------------------------------------------
870.3100                                 90-Day oral toxicity        NOAEL = 1212/1537 mg/kg/day (M/F)
                                          rodents (mouse)
                                                                     LOAEL greater than (>) 1212/1537 mg/kg/day
                                                                      (M/F). No effects noted
----------------------------------------------------------------------------------------------------------------
870.3150                                 90-Day oral toxicity in     NOAEL = 1,000 mg/kg/day (M/F)
                                          nonrodents (dog)
                                                                     LOAEL > 1,000 mg/kg/day (M/F) No effects
                                                                      noted
----------------------------------------------------------------------------------------------------------------
870.3200                                 21/28-Day dermal toxicity   NOAEL = 1,000 mg/kg/day (M/F)
                                          (rabbit)
                                                                     LOAEL > 1,000 mg/kg/day (M/F). No systemic
                                                                      effects noted
----------------------------------------------------------------------------------------------------------------
870.3700a                                Prenatal developmental in   Maternal NOAEL = 100 mg/kg/day
                                          rodents (rat)
                                                                     LOAEL = 300 mg/kg/day, based upon decreased
                                                                      maternal body weight gains during
                                                                      treatment and decreased food consumption
                                                                     Developmental NOAEL was not established
                                                                     LOAEL = 100 mg/kg/day, based upon delays in
                                                                      skeletal ossification and changes in
                                                                      manuspes ossification assessments
----------------------------------------------------------------------------------------------------------------
870.3700a                                Prenatal developmental in   Maternal NOAEL = 600 mg/kg/day
                                          rodents (mouse)
                                                                     LOAEL >600 mg/kg/day; No effects noted
                                                                     Developmental NOAEL = 150 mg/kg/day
                                                                     LOAEL = 600 mg/kg/day, based upon decreased
                                                                      ossification of the cervical vertebrae
                                                                      centra
----------------------------------------------------------------------------------------------------------------
870.3800                                 Reproduction and fertility  Parental/Systemic NOAEL was not established
                                          effects (rat)
                                                                     LOAEL = 0.3 mg/kg/day (M/F), based upon
                                                                      significantly increased plasma tyrosine
                                                                      levels and increased liver weights in F2
                                                                      males
                                                                     Offspring/Systemic NOAEL not established
                                                                     LOAEL = 0.3 mg/kg/day (M/F), based upon
                                                                      significantly increased plasma tyrosine
                                                                      levels in F2 male pups
                                                                     Reproductive NOAEL = 0.3 mg/kg/day
                                                                     LOAEL = 1.1/1.2 mg/kg/day (M/F), based upon
                                                                      decreased F2 mean litter size
----------------------------------------------------------------------------------------------------------------
870.3800                                 Reproduction and fertility  Parental/Systemic NOAEL = 10.1/11.7 mg/kg/
                                          effects (mouse)             day (M/F)
                                                                     LOAEL = 71.4/82.5 mg/kg/day (M/F), based
                                                                      upon increased kidney weights and
                                                                      tyrosinemia in the and F1 males
                                                                     Offspring/Systemic NOAEL not established
                                                                     LOAEL = 2.1/2.4 mg/kg/day (M/F), based upon
                                                                      tyrosinemia and ocular discharge in the F1
                                                                      and F2 offspring
                                                                     Reproductive NOAEL = 1455.5/1652.3 mg/kg/
                                                                      day (M/F)
                                                                     LOAEL > 1455.5/1652.3 mg/kg/day
----------------------------------------------------------------------------------------------------------------
870.4100a                                Chronic toxicity rodents    NOAEL = 56.2/72.4 mg/kg/day (M/F)
                                          (mouse)
                                                                     LOAEL = 1114/1494.5 mg/kg/day (M/F), based
                                                                      upon decreases in body weight gain and
                                                                      food utilization in males
----------------------------------------------------------------------------------------------------------------
870.4100b                                Chronic toxicity dogs       NOAEL was not established
                                                                     LOAEL = 10 mg/kg/day, based upon evidence
                                                                      of tyrosinemia in both sexes and increased
                                                                      incidence of erythrophagocytosis in the
                                                                      mesenteric lymph nodes of females
----------------------------------------------------------------------------------------------------------------
870.4300                                 Combined chronic toxicity/  NOAEL was not established
                                          carcinogenicity rodents
                                          (rat)
                                                                     NOAEL = 0.16/0.19 mg/kg/day (M/F) ocular
                                                                      lesions only]
                                                                     LOAEL = 0.16/0.19 mg/kg/day based kidney
                                                                      and liver weights or hepatocyte fat
                                                                      vacuolation in males
                                                                     LOAEL = 0.48/0.57 mg/kg/day (M/F), based
                                                                      upon ocular lesions, increases in kidney
                                                                      and liver weights, and hepatocyte fat
                                                                      vacuolation in females
                                                                     No evidence of carcinogenicity
----------------------------------------------------------------------------------------------------------------
870.4300                                 Carcinogenicity mice        NOAEL = 49.7/63.5 mg/kg/day (M/F)

[[Page 33190]]

 
                                                                     LOAEL = 898/1103 mg/kg/day (M/F), based
                                                                      upon decreased body weight, body weight
                                                                      gain, and food efficiency in males
                                                                     No evidence of carcinogenicity
----------------------------------------------------------------------------------------------------------------
870.5100                                 Gene Mutation reverse gene  There was no evidence of induced mutant
                                          mutation assay in           colonies over background
                                          bacteria
----------------------------------------------------------------------------------------------------------------
870.5300                                 Gene Mutation in vitro      There were no treatment-related increases
                                          forward gene mutation       in mutant frequency in the presence or
                                          assay in mouse lymphoma     absence of S9 activation
                                          cells
----------------------------------------------------------------------------------------------------------------
870.5375                                 Cytogenetics in vitro       Not clastogenic with S9 activation and
                                          mammalian cytogenetics      equivocal for clastogenic activity without
                                          assay                       S9 activation
----------------------------------------------------------------------------------------------------------------
870.5395                                 bone marrow micronucleus    There was no significant increase in the
                                          assay                       frequency of micronucleated polychromatic
                                                                      erythrocytes in bone marrow after any
                                                                      treatment time.
----------------------------------------------------------------------------------------------------------------
870.6200a                                Acute neurotoxicity         NOAEL = 2,000 mg/kg/day (M/F)
                                          screening battery
                                                                     LOAEL > 2,000 mg/kg/day (M/F)
                                                                     No effects noted
----------------------------------------------------------------------------------------------------------------
870.6200b                                Subchronic neurotoxicity    NOAEL = 0.20/0.23 mg/kg/day (M/F)
                                          screening battery
                                                                     LOAEL = 8.25/9.29 mg/kg/day (M/F), based
                                                                      upon corneal opacities and/or
                                                                      vascularization of the cornea of the eye
                                                                      in males
----------------------------------------------------------------------------------------------------------------
870.7485                                 Metabolism rat              Mesotrione was readily absorbed and
                                                                      distributed in the body. Tissue
                                                                      distribution was about the same in both
                                                                      sexes, although one study showed higher
                                                                      residues in the kidneys in females, with
                                                                      the highest residues of the test compound
                                                                      in the liver and kidney. Higher doses
                                                                      resulted in higher residues in the liver
                                                                      and kidney, while repeated doses resulted
                                                                      in reduced accumulation of residues in all
                                                                      tissues. Levels of radioactivity in
                                                                      tissues of iv-dosed animals were
                                                                      essentially the same as in orally-dosed
                                                                      animals. Over 50% of the administered dose
                                                                      was excreted in the urine in both sexes
                                                                      and around 25% was excreted in the feces
                                                                      within 72 hours. Females exhibited
                                                                      slightly higher total urinary excretion
                                                                      than males, but total fecal excretion was
                                                                      about the same in both sexes. Increasing
                                                                      the dose or repeated doses had little
                                                                      effect on the pattern of excretion in both
                                                                      sexes. The overall pattern of excretion
                                                                      was similar between orally-dosed and iv-
                                                                      dosed rats. The metabolite profile was
                                                                      similar between the sexes in each group
                                                                      and between the single-dosed and repeated-
                                                                      dosed animals. The parent compound,
                                                                      mesotrione, was the major component
                                                                      identified in the urine (> 47%) and feces
                                                                      (> 55%). Minor metabolites identified were
                                                                      MNBA, AMBA, 5-hydroxymesotrione, and 4-
                                                                      hydroxymesotrione.
----------------------------------------------------------------------------------------------------------------
870.7485                                 Metabolism mouse            Metabolism in the mouse was very similar to
                                                                      the rat (above) except that males had
                                                                      slightly increased total fecal excretion
                                                                      when compared to females and, females in
                                                                      the low-dose group excreted higher (1.5x)
                                                                      levels of parent compound in the urine
                                                                      than males. Free mesotrione was the major
                                                                      component in the urine and feces ( 50% of
                                                                      the dose). Minor components in the fecal
                                                                      extracts included AMBA and MNBA.
----------------------------------------------------------------------------------------------------------------

B. Toxicological Endpoints

    The dose at which no adverse effects are observed (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 lowest dose at which adverse effects of concern are 
identified (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. An UF of 100 is routinely used, 10X to account for 
interspecies differences and 10X for intra species differences. A UF of 
3 is used if no NOAEL was achieved in the toxicology study.
    For dietary risk assessment (other than cancer) the Agency uses the 
UF to calculate an acute or chronic reference dose (acute RfD or 
chronic RfD) where the RfD is equal to the NOAEL divided by the 
appropriate UF (RfD = NOAEL/UF). Where an additional safety factor is 
retained due to concerns unique to the FQPA, this additional factor is 
applied to the RfD by dividing the RfD by such additional factor. The 
acute or chronic Population Adjusted Dose (aPAD or cPAD) is a 
modification of the RfD to accommodate this type of FQPA Safety Factor.
    For non-dietary risk assessments (other than cancer) the UF is used 
to determine the LOC. For example, when 100 is the appropriate UF (10X 
to account for interspecies differences and 10X for intraspecies 
differences) the

[[Page 33191]]

LOC is 100. To estimate risk, a ratio of the NOAEL to exposures (margin 
of exposure (MOE) = NOAEL/exposure) is calculated and compared to the 
LOC.
    The linear default risk methodology (Q*) is the primary method 
currently used by the Agency to quantify carcinogenic risk. The Q* 
approach assumes that any amount of exposure will lead to some degree 
of cancer risk. A Q* is calculated and used to estimate risk which 
represents a probability of occurrence of additional cancer cases 
(e.g., risk is expressed as 1 x 10-\6\ or one in a million). 
Under certain specific circumstances, MOE calculations will be used for 
the carcinogenic risk assessment. In this non-linear approach, a 
``point of departure'' is identified below which carcinogenic effects 
are not expected. The point of departure is typically a NOAEL based on 
an endpoint related to cancer effects though it may be a different 
value derived from the dose response curve. To estimate risk, a ratio 
of the point of departure to exposure (MOEcancer = point of 
departure/exposures) is calculated. A summary of the toxicological 
endpoints for mesotrione used for human risk assessment is shown in the 
following Table 2:

      Table 2.--Summary of Toxicological Dose and Endpoints for Mesotrione for Use in Human Risk Assessment
----------------------------------------------------------------------------------------------------------------
                                                                 FQPA SF* and Level of
          Exposure Scenario               Dose Used in Risk         Concern for Risk     Study and Toxicological
                                            Assessment, UF             Assessment                Effects
----------------------------------------------------------------------------------------------------------------
Acute Dietary all populations          Not Applicable           Not Applicable           No appropriate study
                                                                                          available.
----------------------------------------------------------------------------------------------------------------
Chronic Dietary all populations        LOAEL= 2.1 mg/kg/day;    FQPA SF = 10X; cPAD =    Reproduction Study -
                                        UF = 300 [10 x 3];       chronic RfD/FQPA SF =    mouse
                                        Chronic RfD = 0.007 mg/  0.0007 mg/kg/day
                                        kg/day
                                                                                         Offspring LOAEL = 2.1
                                                                                          mg/kg/day based upon
                                                                                          tyrosinemia in F1 and
                                                                                          F2a offspring and
                                                                                          ocular discharge in F1
                                                                                          pups**.
----------------------------------------------------------------------------------------------------------------
Oral, Short-term (1-7 days)                   No residential uses. An endpoint was not proposed/selected.
 (Residential)
----------------------------------------------------------------------------------------------------------------
Oral, Intermediate-term (1 week -             No residential uses. An endpoint was not proposed/selected.
 several months) (Residential)
----------------------------------------------------------------------------------------------------------------
Cancer (oral, dermal, inhalation)      not likely               Not Applicable           Acceptable oral rat and
                                                                                          mouse carcinogenicity
                                                                                          studies; no evidence
                                                                                          of carcinogenic or
                                                                                          mutagenic potential.
----------------------------------------------------------------------------------------------------------------
\*\ The reference to the FQPA Safety Factor refers to any additional safety factor retained due to concerns
  unique to the FQPA.
\**\ Plasma tyrosine levels were increased in the rat, mouse and dog in the chronic and reproduction studies in
  which levels were measured. The ocular, liver and kidney effects are believed to be mediated by the high
  tyrosine levels in the blood caused by inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD).
  Even though the rat is the most sensitive species to this effect compared to the dog and the mouse, EPA
  concludes that the mouse is a more appropriate model for assessing human risk than is the rat.

C. Exposure Assessment

     1. Dietary exposure from food and feed uses. No tolerances have 
been previously established (40 CFR part 180) for residues of 
mesotrione in or on any variety of raw agricultural commodities. Risk 
assessments were conducted by EPA to assess dietary exposures from 
mesotrione in food as follows:
     i. Acute exposure. Acute dietary 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 one day 
or single exposure. No appropriate study available show any acute 
dietary effects of concern.
     ii. Chronic exposure. In conducting this chronic dietary risk 
assessment the Dietary Exposure Evaluation Model (DEEM) 
analysis evaluated the individual food consumption as reported by 
respondents in the USDA 1989-1992 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: residue levels are at the recommended tolerances 
for field corn, and 100% of the crop field corn is treated with 
mesotrione. The %cPAD for the general U.S. population is 1.8% and for 
the most sensitive population subgroups, All Infants (< 1 year old), is 
4.3%.
     iii. Cancer. Acceptable oral rat and mouse carcinogenicity studies 
showed no evidence of carcinogenic or mutagenic potential.
    2. Dietary exposure from drinking water. The Agency lacks 
sufficient monitoring exposure data to complete a comprehensive dietary 
exposure analysis and risk assessment for mesotrione 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 mesotrione.
    The Agency uses the Generic Estimated Environmental Concentration 
(GENEEC) or the Pesticide Root Zone/Exposure Analysis Modeling System 
(PRZM/EXAMS) to estimate pesticide concentrations in surface water and 
SCI-GROW, which predicts pesticide concentrations in groundwater. In 
general, EPA will use GENEEC (a tier 1 model) before using PRZM/EXAMS 
(a tier 2 model) for a screening-level assessment for surface water. 
The GENEEC model is a subset of the PRZM/EXAMS model that uses a 
specific high-end runoff scenario for pesticides. GENEEC incorporates a 
farm pond scenario, while PRZM/EXAMS incorporate an index reservoir 
environment in place of the previous pond scenario. The PRZM/EXAMS 
model includes a percent crop area factor as an adjustment to account 
for the maximum percent crop coverage within a watershed or drainage 
basin.
    None of these models include consideration of the impact processing 
(mixing, dilution, or treatment) of raw water for distribution as 
drinking water would likely have on the removal of pesticides from the 
source water. The

[[Page 33192]]

primary use of these models by the Agency at this stage is to provide a 
coarse screen for sorting out pesticides for which it is highly 
unlikely that drinking water concentrations would ever exceed human 
health levels of concern.
    Since the models used are considered to be screening tools in the 
risk assessment process, the Agency does not use estimated 
environmental concentrations (EECs) from these models to quantify 
drinking water exposure and risk as a %RfD or %PAD. Instead drinking 
water levels of comparison (DWLOCs) are calculated and used as a point 
of comparison against the model estimates of a pesticide's 
concentration in water. DWLOCs are theoretical upper limits on a 
pesticide's concentration in drinking water in light of total aggregate 
exposure to a pesticide in food, and from residential uses. Since 
DWLOCs address total aggregate exposure to mesotrione they are further 
discussed in the aggregate risk sections below.
    Based on the GENEEC (Version 1.2) and SCI-GROW models the estimated 
environmental concentrations (EECs) of mesotrione for acute exposures 
are estimated to be 20 parts per billion (ppb) for surface water and 
0.15 ppb for ground water. The EECs for chronic exposures are estimated 
to be 4.3 ppb for surface water and 0.15 ppb for ground 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). Mesotrione is not 
registered for use on any sites that would result in residential 
exposure.
    4. Cumulative exposure to substances with a common mechanism of 
toxicity. Section 408(b)(2)(D)(v) 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 does not have, at this time, available data to determine 
whether mesotrione has a common mechanism of toxicity with other 
substances or how to include this pesticide in a cumulative risk 
assessment. Unlike other pesticides for which EPA has followed a 
cumulative risk approach based on a common mechanism of toxicity, 
mesotrione 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 mesotrione 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 final rule 
for Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997).

D. Safety Factor for Infants and Children

    1. Safety factor for infants and children--i. In general. FFDCA 
section 408 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 
data base on toxicity and exposure unless EPA determines 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 margin of exposure (MOE) analysis or through 
using uncertainty (safety) factors in calculating a dose level that 
poses no appreciable risk to humans.
    ii. Prenatal and postnatal sensitivity. There is quantitative 
evidence of increased susceptibility demonstrated in the oral prenatal 
developmental toxicity studies in rats, mice, and rabbits. Delayed 
ossification was seen in the fetuses at doses below those at which 
maternal toxic effects were noted. Maternal toxic effects in the rat 
were decreased body weight gain during treatment and decreased food 
consumption and in the rabbit, abortions and GI effects.
    2. Conclusion. The FQPA safety factor (10x) is retained in 
assessing the risk posed because there is quantitative evidence of 
increased susceptibility of the young exposed to mesotrione in the 
prenatal developmental toxicity studies in mice, rats, and rabbits and 
in the multi-generation reproduction study in mice, there is 
qualitative evidence of increased susceptibility of the young exposed 
to mesotrione in the multi-generation reproduction study in rats; and a 
Developmental Neurotoxicity Study is required to assess the effects of 
tyrosinemia on the developing nervous system exposed to mesotrione.

E. Aggregate Risks and Determination of Safety

    To estimate total aggregate exposure to a pesticide from food, 
drinking water, and residential uses, the Agency calculates drinking 
water level of comparison (DWLOCs) which are used as a point of 
comparison against the model estimates of a pesticide's concentration 
in water (EECs). DWLOC values are not regulatory standards for drinking 
water. DWLOCs 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. In calculating a DWLOC, the 
Agency determines how much of the acceptable exposure (i.e., the PAD) 
is available for exposure through drinking water [e.g., allowable 
chronic water exposure (mg/kg/day) = cPAD - (average food + residential 
exposure)]. This allowable exposure through drinking water is used to 
calculate a DWLOC.
    A DWLOC will vary depending on the toxic endpoint, drinking water 
consumption, and body weights. Default body weights and consumption 
values as used by the USEPA Office of Water are used to calculate 
DWLOCs: 2L/70 kg (adult male), 2L/60 kg (adult female), and 1L/10 kg 
(child). Default body weights and drinking water consumption values 
vary on an individual basis. This variation will be taken into account 
in more refined screening-level and quantitative drinking water 
exposure assessments. Different populations will have different DWLOCs. 
Generally, a DWLOC is calculated for each type of risk assessment used: 
acute, short-term, intermediate-term, chronic, and cancer.
    When EECs for surface water and groundwater are less than the 
calculated DWLOCs, OPP concludes with reasonable certainty that 
exposures to the pesticide in drinking water (when considered along 
with other sources of exposure for which OPP has reliable data) would 
not result in unacceptable levels of aggregate human health risk at 
this time. Because OPP considers the aggregate risk resulting from 
multiple exposure pathways associated with a pesticide's uses, levels 
of comparison in drinking water may vary as those uses change. If new 
uses are added in the future, OPP will reassess the potential impacts 
of residues of the pesticide in drinking water as a part of the 
aggregate risk assessment process.
    1. Acute risk. Acute doses and endpoints were not selected for the 
general U.S. population (including infants and children) or the females 
13-50 years old population subgroup for mesotrione; therefore, an acute 
dietary exposure analysis was not performed.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that exposure to 
mesotrione from food will utilize 1.8% of the cPAD for the U.S. 
population, 4.3% of the cPAD for

[[Page 33193]]

All Infants (< 1 year old) and 4.2% of the cPAD for Children 1-6 years 
old. There are no residential uses for mesotrione that result in 
chronic residential exposure to mesotrione.

               Table 3.--Aggregate Risk Assessment for Chronic (Non-Cancer) Exposure to mesotrione
----------------------------------------------------------------------------------------------------------------
                                                                             Surface       Ground
              Population Subgroup                cPAD mg/kg/     % cPAD     Water EEC    Water EEC     Chronic
                                                     day         (Food)       (ppb)        (ppb)     DWLOC (ppb)
----------------------------------------------------------------------------------------------------------------
U.S. Population                                       0.0007          1.8          4.3         0.15           24
----------------------------------------------------------------------------------------------------------------
All infants (< 1 year old)                            0.0007          4.3          4.3         0.15          6.7
----------------------------------------------------------------------------------------------------------------
Children (1-6 years old)                              0.0007          4.2          4.3         0.15          6.7
----------------------------------------------------------------------------------------------------------------
 Females (13-50 years old)                            0.0007          1.4          4.3         0.15           21
----------------------------------------------------------------------------------------------------------------

     Mesotrione 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.
     3. Aggregate cancer risk for U.S. population. Based on the lack of 
carcinogenic response in rats and mice and the lack of mutagenic 
effects, and that there are no data in the literature or SAR 
information to indicate carcinogenic potential, no cancer risk is 
posed.
     4. 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 mesotrione residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (high pressure liquid 
chromatography) is available to enforce the tolerance expression. The 
method may be requested from: Calvin Furlow, PIRIB, IRSD (7502C), 
Office of Pesticide Programs, Environmental Protection Agency, 1200 
Pennsylvania Ave., NW, Washington, DC 20460; telephone number: (703) 
305-5229; e-mail address: [email protected].

B. International Residue Limits

    There are no CODEX, Canadian, or Mexican tolerances/Maximum Residue 
Levels for mesotrione residues. Thus, harmonization is not an issue at 
this time.

C. Conditions

    Conversion of the mesotrione registration to unconditional under 
section 3(c)(5) of Federal Insecticide and Fungicide Act (FIFRA) as 
amended may be considered upon submission of adequate storage stability 
data in the plant and livestock metabolism studies, revised 
interference study, developmental neurotoxicity study (DNT) in the 
mouse, and an 8 day inhalation study.

V. Conclusion

    Therefore, the tolerance is established for residues of mesotrione, 
2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione, in or on 
the raw agricultural commodities field corn grain, field corn forage 
and field corn stover at 0.01 ppm.

VI. Objections and Hearing Requests

    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. Although the procedures in those 
regulations require some modification to reflect the amendments made to 
the FFDCA by the FQPA of 1996, EPA will continue to use those 
procedures, with appropriate adjustments, until the necessary 
modifications can be made. The new section 408(g) provides essentially 
the same process for persons to ``object'' to a regulation for an 
exemption from the requirement of a tolerance issued by EPA under new 
section 408(d), as was provided in the old FFDCA sections 408 and 409. 
However, the period for filing objections is now 60 days, rather than 
30 days.

A. What Do I Need to Do to File an Objection or Request a Hearing?

    You must file your objection or request a hearing on this 
regulation in accordance with the instructions provided in this unit 
and in 40 CFR part 178. To ensure proper receipt by EPA, you must 
identify docket control number OPP-301138 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 August 
20, 2001.
    1. Filing the request. Your objection must specify the specific 
provisions in the regulation that you object to, and the grounds for 
the objections (40 CFR 178.25). If a hearing is requested, the 
objections must include a statement of the factual issues(s) on which a 
hearing is requested, the requestor's contentions on such issues, and a 
summary of any evidence relied upon by the objector (40 CFR 178.27). 
Information submitted in connection with an objection or hearing 
request may be claimed confidential by marking any part or all of that 
information as CBI. Information so marked will not be disclosed except 
in accordance with procedures set forth in 40 CFR part 2. A copy of the 
information that does not contain CBI must be submitted for inclusion 
in the public record. Information not marked confidential may be 
disclosed publicly by EPA without prior notice.
    Mail your written request to: Office of the Hearing Clerk (1900), 
Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 
Washington, DC 20460. You may also deliver your request to the Office 
of the Hearing Clerk in Rm. C400, Waterside Mall, 401 M St., SW., 
Washington, DC 20460. The Office of the Hearing Clerk is open from 8 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The 
telephone number for the Office of the Hearing Clerk is (202) 260-4865.
    2. Tolerance fee payment. If you file an objection or request a 
hearing, you must also pay the fee prescribed by 40 CFR 180.33(i) or 
request a waiver of that fee pursuant to 40 CFR 180.33(m). You must 
mail the fee to: EPA Headquarters Accounting Operations Branch, Office 
of Pesticide Programs, P.O. Box 360277M, Pittsburgh, PA 15251. Please 
identify the fee submission by labeling it ``Tolerance Petition Fees.''
    EPA is authorized to waive any fee requirement ``when in the 
judgement of

[[Page 33194]]

the Administrator such a waiver or refund is equitable and not contrary 
to the purpose of this subsection.'' For additional information 
regarding the waiver of these fees, you may contact James Tompkins by 
phone at (703) 305-5697, by e-mail at [email protected], or by 
mailing a request for information to Mr. Tompkins at Registration 
Division (7505C), Office of Pesticide Programs, Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
    If you would like to request a waiver of the tolerance objection 
fees, you must mail your request for such a waiver to: James Hollins, 
Information Resources and Services Division (7502C), Office of 
Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460.
    3. Copies for the Docket. In addition to filing an objection or 
hearing request with the Hearing Clerk as described in Unit VI.A., you 
should also send a copy of your request to the PIRIB for its inclusion 
in the official record that is described in Unit I.B.2. Mail your 
copies, identified by docket control number OPP-301138, to: Public 
Information and Records Integrity Branch, Information Resources and 
Services Division (7502C), Office of Pesticide Programs, Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. 
In person or by courier, bring a copy to the location of the PIRIB 
described in Unit I.B.2. You may also send an electronic copy of your 
request via e-mail to: [email protected]. Please use an ASCII file 
format and avoid the use of special characters and any form of 
encryption. Copies of electronic objections and hearing requests will 
also be accepted on disks in WordPerfect 6.1/8.0 or ASCII file format. 
Do not include any CBI in your electronic copy. You may also submit an 
electronic copy of your request at many Federal Depository Libraries.

B. When Will the Agency Grant a Request for a Hearing?

    A request for a hearing will be granted if the Administrator 
determines that the material submitted shows the following: There is a 
genuine and substantial issue of fact; there is a reasonable 
possibility that available evidence identified by the requestor would, 
if established resolve one or more of such issues in favor of the 
requestor, taking into account uncontested claims or facts to the 
contrary; and resolution of the factual issues(s) in the manner sought 
by the requestor would be adequate to justify the action requested (40 
CFR 178.32).

VII. Regulatory Assessment Requirements

    This final rule establishes a tolerance under FFDCA section 408(d) 
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). 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 FFDCA section 408(d), 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, 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 FFDCA section 408(n)(4). 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.''

VIII. Submission to Congress and the Comptroller General

    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 record 
keeping requirements.


[[Page 33195]]


    Dated: June 4, 2001.
Joseph Merenda,
Acting Director, Office of Pesticide Programs.

    Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

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

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

    2. Part 180 is amended by adding Sec. 180.571 to read as follows:


Sec. 180.571   Mesotrione; tolerances for residues.

    (a) General. Tolerances are established for residues of the 
herbicide mesotrione, 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-
cyclohexanedione, in or on the following commodities:

------------------------------------------------------------------------
                                                              Parts per
                         Commodity                             million
------------------------------------------------------------------------
Corn, field, forage                                                 0.01
Corn, field, grain                                                  0.01
Corn, field, stover                                                 0.01
------------------------------------------------------------------------

    (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]

[FR Doc. 01-15614 Filed 6-20-01; 8:45 am]
BILLING CODE 6560-50-S