[Federal Register Volume 66, Number 106 (Friday, June 1, 2001)]
[Rules and Regulations]
[Pages 29705-29712]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-13774]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-301128; FRL-6781-5]
RIN 2070-AB78


Prohexadione Calcium; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

SUMMARY: This regulation establishes a tolerance for residues of 
prohexadione calcium (calcium 3-oxido-5-oxo-4-propionylcyclohex-3-
enecarboxylate) in or on grass forage, grass hay, grass straw and grass 
seed screenings. K-I Chemical U.S.A. Inc. requested these tolerances 
under the Federal Food, Drug, and Cosmetic Act, as amended by the Food 
Quality Protection Act of 1996.

DATES: This regulation is effective June 1, 2001. Objections and 
requests for hearings, identified by docket control number OPP-301128, 
must be received by EPA on or before July 31, 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 theSUPPLEMENTARY 
INFORMATION. To ensure proper receipt by EPA, your objections and 
hearing requests must identify docket control number OPP-301128 in the 
subject line on the first page of your response.

FOR FURTHER INFORMATION CONTACT: By mail: Cynthia Giles-Parker (PM 22), 
Registration Division (7505C), Office of Pesticide Programs, 
Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 
Washington, DC 20460; telephone number: (703) 305-7740; 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
           Categories                 NAICS codes         Potentially
                                                       Affected Entities
------------------------------------------------------------------------
Industry                          111                 Crop production
                                  112                 Animal production
                                  311                 Food manufacturing
                                  32532               Pesticide
                                                       manufacturing
------------------------------------------------------------------------

    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 to 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 theFederal 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.
    2. In person. The Agency has established an official record for 
this action under docket control number OPP-301128. 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),

[[Page 29706]]

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 March 28, 2001 (66 FR 16921) (FRL-6769-
9), 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) for tolerance by K-I Chemical 
U.S.A. Inc., Westchester Financial Center, 11 Martine Avenue, 9th 
Floor, White Plains, NY, 10606. This notice included a summary of the 
petition prepared by K-I Chemical U.S.A. Inc., the registrant. There 
were no comments received in response to the notice of filing.
    The petition requested that 40 CFR 180.547 be amended by 
establishing a tolerance for residues of the plant growth regulator 
prohexadione calcium, calcium 3-oxido-5-oxo-4- propionylcyclohex-3-
enecarboxylate in or on grass forage at 0.10 part per million (ppm), 
grass hay at 0.10 ppm, grass straw at 1.2 ppm and grass seed screenings 
at 3.5 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 prohexadione calcium, 
calcium 3-oxido-5-oxo-4-propionylcyclohex-3-enecarboxylate in or on 
grass forage at 0.10 ppm, grass hay at 0.10 ppm, grass straw at 1.2 ppm 
and grass seed screenings at 3.5 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 prohexadione 
calcium 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 rodents       NOAEL: Males: 73.1 mg/kg/
 (rat)                                       day; Females: 80.4 mg/kg/
                                             day LOAEL: Males: 734 mg/kg/
                                             day; Females: 815 mg/kg/day
                                             based on squamous cell
                                             hyperplasia of the
                                             forestomach.
------------------------------------------------------------------------
870.3100 90-Day oral toxicity rodents       NOAEL: Males: 10,244 mg/kg/day;
                                             Females: 11,916
                                             mg/kg/day (highest dose
                                             tested)LOAEL: Males:
                                             >10,244 mg/kg/day; Females:
                                             >11,916 mg/kg/day
------------------------------------------------------------------------
870.3150 90-Day oral toxicity in            NOAEL = 80 mg/kg/day LOAEL =
 nonrodents (dog)                            400 mg/kg/day based on
                                             moderate cortical areas of
                                             dilated basophilic tubules
                                             in the kidneys and
                                             decreased potassium levels.
------------------------------------------------------------------------
870.3200 21/28-Day dermal toxicity          DATA GAP
------------------------------------------------------------------------
870.3250 90-Day dermal toxicity             NA
------------------------------------------------------------------------
870.3700a Prenatal developmental toxicity   Maternal NOAEL 1,000 mg/kg/day (limit
                                             dose)LOAEL = Not observed
                                             Developmental NOAEL 1,000 mg/kg/day (limit
                                             dose) LOAEL = Not observed
------------------------------------------------------------------------
870.3700b Prenatal developmental toxicity   Maternal NOAEL = 40 mg/kg/
 in nonrodents (rabbit)                      dayLOAEL = 200 mg/kg/day
                                             based on increased
                                             mortality,abortions, and
                                             decreased maternal body
                                             weight gain.Developmental
                                             NOAEL 200 mg/kg/
                                             day LOAEL = Not
                                             observed(Due to severe
                                             mortality at 750 mg/kg/day,
                                             200 mg/kg/day wasdeemed the
                                             high dose for evaluation)
------------------------------------------------------------------------
870.3700b Prenatal developmentaltoxicity    Maternal NOAEL = 150 mg/kg/day LOAEL =
                                             Not observed Developmental
                                             NOAEL 150 mg/kg/
                                             day LOAEL = Not observed
------------------------------------------------------------------------

[[Page 29707]]

 
870.3700b Prenatal developmentaltoxicity    Maternal NOAEL = 100 mg/kg/
 in nonrodents (rabbit)                      dayLOAEL = 350 mg/kg/day
                                             based on premature
                                             deliveries.Developmental
                                             NOAEL 350 mg/kg/
                                             day LOAEL = Not observed
------------------------------------------------------------------------
870.38002-Generation Reproductionand        Parental/Systemic NOAEL =
 fertility effects rats                      35.5 mg/kg/dayLOAEL = 385
                                             mg/kg/day based on
                                             increased
                                             mortality.Reproductive
                                             NOAEL 3,850 mg/
                                             kg/dayLOAEL >3,850 mg/kg/
                                             dayOffspring NOAEL = 385 mg/
                                             kg/dayLOAEL = 3850 mg/kg/
                                             day based on decreased pup
                                             body weight.
------------------------------------------------------------------------
870.4100 Chronic toxicity dogs              NOAEL = 20 mg/kg/day LOAEL =
                                             200 mg/kg/daybased on
                                             histopathological changes
                                             in thekidneys and increased
                                             urinary volumeand sodium
                                             concentrations.
------------------------------------------------------------------------
870.4300 Chronictoxicity/carcinogenicity    NOAEL = 93.9 mg/kg/dayLOAEL
 rats                                        = 469 mg/kg/day based on
                                             decreased WBC in males.No
                                             evidence of carcinogenicity
------------------------------------------------------------------------
870.4200 Carcinogenicity mice               NOAEL = 279 mg/kg/dayLOAEL =
                                             2847 mg/kg/day based on
                                             decreased bodyweight gain
                                             and food utilization
                                             andmicroscopic changes in
                                             the stomachs of males.No
                                             evidence of carcinogenicity
------------------------------------------------------------------------
870.5100 Bacterial reversemutation assay    Negative with and without S-
 (Ames test)                                 9activation up to the
                                             highest dose tested (5,000
                                             g/plate).
------------------------------------------------------------------------
870.5300In vitro mammalian gene mutation    Negative with S-9
 assay                                       activationup to 475 g/mL. Negative without S-
                                             9activation up to 500
                                             g/mL. Compound
                                             testedto concentrations
                                             limited by solubility.
------------------------------------------------------------------------
870.5375In vitro mammalian                  Increase in polyploidy in
 chromosomeaberration (Chinese Hampster      theabsence of S9 activation
 Ovary (CHO) cells)                          at 500 g/mL for6
                                             hours at the 24-hour cell
                                             harvest time;effect not
                                             observed after treatments
                                             of 24-or 48-hours. No
                                             increase in
                                             aberrationfrequency at any
                                             concentration orharvest
                                             time with or without S9.
                                             Compound wastested up to
                                             concentrations limited by
                                             solubility.
------------------------------------------------------------------------
870.5385 In vivomammalian chromosome        Negative at 6, 24, and48-
 aberration (rat bone marrow cells)          hour sacrifices. Compound
                                             testedto the limit dose.
------------------------------------------------------------------------
870.5395 Mammalian erythrocytemicronucleus  Negative at 24, 48, and 72
 test                                        hour sacrifices. Noincrease
                                             in the frequency of
                                             micronucleatedpolychromatic
                                             erythrocytes in bone
                                             marrow.
------------------------------------------------------------------------
870.5550 UDS in primary rat hepatocytes     Negative up to cytotoxic
                                             concentration (500 g/mL).
------------------------------------------------------------------------
870.5500 Rec assay withBacillus subtilis    Negative for DNA damage when
                                             tested upto the limit dose
                                             (5,000 g/mL) both
                                             with and without S9.
------------------------------------------------------------------------
870.6200a Acute neurotoxicityscreening      NOAEL 2,000 mg/kg
 battery                                     LOAEL = Not observed
------------------------------------------------------------------------
870.6200b Subchronic                        NOAEL 1148 (M) or
 neurotoxicityscreening battery              1348(F) mg/kg/day LOAEL =
                                             Not observed
------------------------------------------------------------------------
870.6300 Developmental neurotoxicity        NA
------------------------------------------------------------------------
870.7485 Metabolism and pharmacokinetics    Following oral treatment of
                                             rats,prohexadione calcium
                                             was rapidlyabsorbed with
                                             highest tissue/
                                             carcassconcentrations
                                             obtained within30 minutes;
                                             however, absorptionbecame
                                             saturated at the highest
                                             dose.The test material did
                                             not accumulatein the
                                             tissues. For low dose
                                             animals,renal excretion was
                                             the primary route
                                             ofelimination. At the high
                                             dose, fecalexcretion became
                                             the primary route
                                             ofelimination. The primary
                                             excreta(both feces and
                                             urine) metabolite
                                             wasidentified as the free
                                             acid.
------------------------------------------------------------------------
870.7600 Dermal penetration                 NA
------------------------------------------------------------------------

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, 10 x  to account for

[[Page 29708]]

interspecies differences and 10 x  for intraspecies differences.
    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 
(10 x  to account for interspecies differences and 10 x  for 
intraspecies differences) the 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 prohexadione calcium used 
for human risk assessment is shown in the following Table 2:

 Table 2.--Summary of Toxicological Dose and Endpoints for prohexadione calcium for Use in Human Risk Assessment
----------------------------------------------------------------------------------------------------------------
                                          Dose Used in Risk       FQPA SF and LOC for    Study and Toxicological
          Exposure Scenario                 Assessment, UF          Risk Assessment              Effects
----------------------------------------------------------------------------------------------------------------
Acute Dietary                          NA                       NA                       no adverse effects of
                                                                                          concern observed in
                                                                                          oral, developmental,
                                                                                          and neurotoxicity
                                                                                          studies in rats and
                                                                                          rabbits, attributable
                                                                                          to a single exposure
                                                                                          dose
----------------------------------------------------------------------------------------------------------------
Chronic Dietary                        NOAEL= 80 mg/kg/day UF   FQPA SF = 1 x  cPAD =    Subchronic & chronic
                                        = 100 Chronic RfD =      chronic RfD FQPA SF =    toxicity-dog LOAEL =
                                        0.80 mg/kg/day           0.80 mg/kg/day           200 mg/kg/day based on
                                                                                          histopathological
                                                                                          changes in the kidneys
                                                                                          (dilated basophilic
                                                                                          tubules) and clinical
                                                                                          chemistry changes
----------------------------------------------------------------------------------------------------------------
Short-Term Dermal (1-7 days)           Oral Maternal NOAEL =    LOC for MOE = 100        Developmental toxicity-
 (Occupational/Residential)             100 mg/kg/day            (Occupational)           rabbit Maternal LOAEL
                                        Estimated dermal                                  = 350 mg/kg/day based
                                        absorption rate 25%                               on premature
                                                                                          deliveries
----------------------------------------------------------------------------------------------------------------
Intermediate-Term Dermal (1 week -     Oral NOAEL = 80 mg/kg/   LOC for MOE =100         Subchronic toxicity-dog
 several months) (Occupational/         day Estimated            (Occupational)           LOAEL = 400 mg/kg/day
 Residential)                           absorption rate 25%                               based on moderate
                                                                                          cortical areas of
                                                                                          dilated basophilic
                                                                                          tubules in the kidneys
                                                                                          and decreased
                                                                                          potassium levels
----------------------------------------------------------------------------------------------------------------
Long-Term Dermal (several months -     Oral NOAEL = 80 mg/kg/   LOC for MOE = 100        Subchronic & chronic
 lifetime) (Occupational/Residential)   day Estimated            (Occupational)           toxicity-dog LOAEL =
                                        absorption rate 25%                               200 mg/kg/day based on
                                                                                          histopathological
                                                                                          changes in the kidneys
                                                                                          (dilated basophilic
                                                                                          tubules) and clinical
                                                                                          chemistry changes
----------------------------------------------------------------------------------------------------------------
Short-Term Inhalation (1-7 days)       Oral Maternal NOAEL=     LOC for MOE = 100        Developmental toxicity-
 (Occupational/Residential)             100 mg/kg/day            (Occupational)           rabbit LOAEL = 350 mg/
                                        (inhalation absorption                            kg/day based on
                                        rate = 100%)                                      premature deliveries
----------------------------------------------------------------------------------------------------------------
Intermediate-Term Inhalation (1 week - Oral NOAEL= 80 mg/kg/    LOC for MOE = 100        Subchronic toxicity-dog
  several months) (Occupational/        day (inhalation          (Occupational)           LOAEL = 400 mg/kg/day
 Residential)                           absorption rate =                                 based on moderate
                                        100%)                                             cortical areas of
                                                                                          dilated basophilic
                                                                                          tubules in the kidneys
                                                                                          and decreased
                                                                                          potassium levels
----------------------------------------------------------------------------------------------------------------
Long-Term Inhalation(several months -  Oral NOAEL= 80 mg/kg/    LOC for MOE = 100        Subchronic & chronic
 lifetime)(Occupational/Residential)    day (inhalation          (Occupational)           toxicity-dog LOAEL =
                                        absorption rate =                                 200 mg/kg/day based on
                                        100%)                                             histopathological
                                                                                          changes in the kidneys
                                                                                          (dilated basophilic
                                                                                          tubules) and clinical
                                                                                          chemistry changes
----------------------------------------------------------------------------------------------------------------

[[Page 29709]]

 
Cancer (oral, dermal, inhalation)      Not likely human         NA                       No evidence of
                                        carcinogen                                        carcinogenic
                                                                                          potential, therefore,
                                                                                          cancer risk assessment
                                                                                          is not required
----------------------------------------------------------------------------------------------------------------

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. Tolerances have been 
established (40 CFR 180.547) for the residues of prohexadione calcium, 
in or on a variety of raw agricultural commodities. Risk assessments 
were conducted by EPA to assess dietary exposures from prohexadione 
calcium 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. An acute dietary risk assessment was not performed 
because there were no adverse effects of concern observed in 
neurotoxicity studies, oral toxicology studies, including maternal 
toxicity in the developmental toxicity studies in rats and rabbits, 
that were attributable to a single exposure dose.
    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: Tolerance level residues (pome fruit, peanuts, animal 
feeds) and 100% CT was assumed for all commodities. Residues were not 
found to concentrate in processed apples; therefore, concentration 
factors were not used (apple juice, cider).
    iii. Cancer. In accordance with the EPA Draft Guidelines for 
Carcinogen Risk Assessment (July, 1999), prohexadione calcium is 
classified as not likely to be carcinogenic to humans by all routes of 
exposure based upon lack of evidence of carcinogenicity in rats and 
mice.
    2. Dietary exposure from drinking water. The Agency lacks 
sufficient monitoring exposure data to complete a comprehensive dietary 
exposure analysis and risk assessment for prohexadione calcium 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 prohexadione calcium.
    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 incorporates 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 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 prohexadione calcium they 
are further discussed in the aggregate risk sections below.
    Based on the GENEEC and SCI-GROW models the estimated environmental 
concentrations (EECs) of prohexadione calcium for acute exposures are 
estimated to be 35.6 parts per billion (ppb) for surface water and 
0.001 ppb for ground water. The EECs for chronic exposures are 
estimated to be 7.73 ppb for surface water and 0.001 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). Prohexadione calcium 
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 prohexadione calcium 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, 
prohexadione calcium 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 prohexadione calcium 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

[[Page 29710]]

Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997).

D. Safety Factor for Infants and Children

    1. 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.
    2. Prenatal and postnatal sensitivity. The prenatal and postnatal 
toxicology data base for prohexadione is adequate for FQPA 
considerations. The results of these studies indicated no quantitative 
or qualitative increase in susceptibility of rats or rabbits to  in 
utero and/or postnatal exposure to prohexadione. A developmental 
neurotoxicity study is not required.
    3. Conclusion. There is a complete toxicity data base for 
prohexadione calcium and exposure data are complete or are estimated 
based on data that reasonably accounts for potential exposures. The 
FQPA Safety Factor is 1 x  (reduced from 10 x ). In assessing the risk 
posed by prohexadione calcium the safety factor could be removed 
because: (i) The prenatal and postnatal toxicology data base is 
complete, there is no indication of increased susceptibility, and a 
developmental neurotoxicity study is not required, and (ii) the food 
and drinking water exposure assessments will not underestimate the 
potential exposures for infants and children from the use of 
prohexadione calcium (currently there are no proposed residential uses 
and, therefore, non-occupational exposure is not expected).

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 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 dietary risk assessment is not expected 
because there were no adverse effects of concern observed in 
neurotoxicity studies, oral toxicology studies, including maternal 
toxicity in the developmental toxicity studies in rats and rabbits, 
that were attributable to a single exposure dose.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that exposure to 
prohexadione calcium from food will utilize  1 % of the cPAD for the 
U.S. population, 2% of the cPAD for all infants (1 year old) and 2% of 
th cPAD for children 1-6 years of age. There are no residential uses 
for prohexadione calcium that result in chronic residential exposure to 
prohexadione calcium. In addition, there is potential for chronic 
dietary exposure to prohexadione calcium in drinking water. After 
calculating DWLOCs and comparing them to the EECs for surface and 
ground water, EPA does not expect the aggregate exposure to exceed 100% 
of the cPAD, as shown in the following Table 3:

                             Table 3.--Aggregate Risk Assessment for Chronic (Non- Cancer) Exposure to prohexadione calcium
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                       Surface Water EEC       Ground Water EEC
        Population Subgroup              cPAD mg/kg/day           %cPAD (Food)               (ppb)                  (ppb)           Chronic DWLOC (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. Population                      0.80                     1                      7.73                   0.001                  28,000
All Infants ( 1 year old)            0.80                    2                       7.73                   0.001                  8,000
Children 1-6 years old               0.80                    2                       7.73                   0.001                  8,000
Females 13-50 years old              0.80                     1                      7.73                   0.001                  24,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

    3. Short-term risk. Short-term aggregate exposure takes into 
account residential exposure plus chronic exposure to food and water 
(considered to be a background exposure level). Prohexadione calcium 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. Intermediate-term risk. Intermediate-term aggregate exposure 
takes into account residential exposure plus chronic exposure to food 
and water (considered to be a background exposure level). Prohexadione 
calcium 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.

[[Page 29711]]

    5. Aggregate cancer risk for U.S. population. Prohexadione calcium 
is classified as not likely to be carcinogenic to humans by all routes 
of exposure based upon lack of evidence of carcinogenicity in rats and 
mice, therefore, no cancer risk is expected.
    6. Determination of safety. Based on these risk assessments, EPA 
concludes that there is a reasonable certainty that no harm will result 
to the general population, and to infants and children from aggregate 
exposure to prohexadione calcium residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (gas chromatography and mass 
selective detector) is available to enforce the tolerance expression. 
The method may be requested from: Calvin Furlow, PRRIB, 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 is neither a Codex proposal, nor Canadian or Mexican limits 
for residues of prohexadione calcium in/on plant or livestock 
commodities.

C. Conditions

    A 21-day dermal toxicity study in rabbits (OPPTS 870.3200) is 
required.

V. Conclusion

    Therefore, the tolerance is established for residues of 
prohexadione calcium, calcium 3-oxido-5-oxo-4-propionylcyclohex-3-
enecarboxylate in or on grass forage at 0.10 ppm, grass hay at 0.10 
ppm, grass straw at 1.2 ppm and grass seed screenings at 3.5 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-301128 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, 
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 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-301128, 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).

[[Page 29712]]

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, 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 
recordkeeping requirements.


    Dated: May 16, 2001.
James Jones,
Director, Registration Division, 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. Section 180.547 is amended by alphabetically adding commodities 
to the table in paragraph (a) to read as follows:


Sec. 180.547  Prohexadione calcium; tolerances for residues.

    (a) *  *  *

------------------------------------------------------------------------
                 Commodity                        Parts per million
------------------------------------------------------------------------
                      *      *      *      *      *
Grass, forage\1\                            0.10 ppm
Grass, hay\1\                               0.10 ppm
Grass, seed screenings\1\                   3.5 ppm
Grass, straw\1\                             1.2 ppm
                      *      *      *      *      *
------------------------------------------------------------------------
\1\Registration is limited to grasses grown for seed.

* * * * *

[FR Doc. 01-13774 Filed 5-31-01; 8:45 am]
BILLING CODE 6560-50-S