[Federal Register Volume 63, Number 137 (Friday, July 17, 1998)]
[Rules and Regulations]
[Pages 38483-38495]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18987]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300612; FRL-5768-3]
RIN 2070-AB78


Fipronil; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes new tolerances for combined 
residues of fipronil, its metabolites MB46136 and MB45950, and its 
photodegradate MB46513, in or on rice grain and rice straw. In 
pesticide petition (PP) 7F4832, Rhone Poulenc AG, Inc. requested these 
tolerances under the Federal Food, Drug and Cosmetic Act (FFDCA), as 
amended by the Food Quality Protection Act of 1966 (FQPA).

DATES: This regulation is effective July 17, 1998. Objections and 
requests for hearings must be received by EPA on or before September 
15, 1998.

ADDRESSES: Written objections and hearing requests, identified by the 
docket control number, OPP-300612, must be submitted to: Hearing Clerk 
(1900), Environmental Protection Agency, Rm. M3708, 401 M St., SW., 
Washington, DC 20460. Fees accompanying objections and hearing requests 
shall be labeled ``Tolerance Petition Fees'' and forwarded to: EPA 
Headquarters Accounting Operations Branch, OPP (Tolerance Fees), P.O. 
Box 360277M, Pittsburgh, PA 15251. A copy of any objections and hearing 
requests filed with the Hearing Clerk identified by the docket control 
number, OPP-300612, must also be submitted to: Public Information and 
Records Integrity Branch, Information Resources and Services Division 
(7502C), Office of Pesticide Programs, Environmental Protection Agency, 
401 M St., SW., Washington, DC 20460. In person, bring a copy of 
objections and hearing requests to Rm. 119, Crystal Mall #2, 1921 
Jefferson Davis Hwy., Arlington, VA.
    A copy of objections and hearing requests filed with the Hearing 
Clerk may also be submitted electronically by sending electronic mail 
(e-mail) to: [email protected]. Copies of objections and hearing 
requests must be submitted as an ASCII file avoiding the use of special 
characters and any form of encryption. Copies of objections and hearing 
requests will also be accepted on disks in WordPerfect 5.1/6.1 file 
format or ASCII file format. All copies of objections and hearing 
requests in electronic form must be identified by the docket control 
number OPP-300612. No Confidential Business Information (CBI) should be 
submitted through e-mail. Electronic copies of objections and hearing 
requests on this rule may be filed online at many Federal Depository 
Libraries.

FOR FURTHER INFORMATION CONTACT: By mail: Ann Sibold, Registration 
Division (7505C), Office of Pesticide Programs, Environmental 
Protection Agency, 401 M St., SW., Washington, DC 20460. Office 
location, telephone number, and e-mail address: Crystal Mall #2, 1921 
Jefferson Davis Hwy., Arlington, VA, (703) 305-6788, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: In the Federal Register of June 20, 1997 (62 
FR 33641) (FRL-5723-7), EPA issued a notice pursuant to section 408 of 
the FFDCA, 21 U.S.C. 346a(e), announcing the filing of a pesticide 
petition for a tolerance (PP 7F4832) by Rhone Poulenc AG, Inc., P.O. 
Box 12014, 2 T.W. Alexander Drive, Research Triangle Park, NC 27709. 
This notice included a summary of the petition prepared by Rhone 
Poulenc AG, Inc., the registrant. There were 11 comments received in 
response to the notice of filing and all supported establishing the 
tolerance.
    The petition proposed to use a 56% flowable solid (FS) formulation 
(Product name: ICON 6.2 FS Insecticide) to treat rice seed to control 
the pests rice water weevil and chinch bugs.
    The petition further requested that 40 CFR 180.517 be amended by 
establishing new tolerances for combined residues of the insecticide 
fipronil, its metabolites MB46136 and MB45950, and its photodegradate 
MB46513 in or on rice grain at 0.04 parts per million (ppm) and rice 
straw at 0.10 ppm. Tolerances for residues of fipronil (expressed as 
fipronil and its metabolites MB45950 and MB46136) in or on animal 
commodities have recently been established (40 CFR 180.517(a)).
    Fipronil is registered in the United States for use on field corn, 
on golf course and commercial turf, on pets, and in roach and ant bait 
stations.

I. Risk Assessment and Statutory Findings

    New 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) of the FFDCA defines ``safe'' to mean that ``there is 
a reasonable certainty that no harm will result from aggregate exposure 
to the pesticide chemical residue, including all anticipated dietary 
exposures and all other exposures for which there is reliable 
information.'' This includes exposure through drinking water and in 
residential settings, but does not include occupational exposure. 
Section 408(b)(2)(C) 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

[[Page 38484]]

exposure to the pesticide chemical residue. . . .''
    EPA performs a number of analyses to determine the risks from 
aggregate exposure to pesticide residues. First, EPA determines the 
toxicity of pesticides based primarily on toxicological studies using 
laboratory animals. These studies address many adverse health effects, 
including (but not limited to) reproductive effects, developmental 
toxicity, toxicity to the nervous system, and carcinogenicity. Second, 
EPA examines exposure to the pesticide through the diet (e.g., food and 
drinking water) and through exposures that occur as a result of 
pesticide use in residential settings.

A. Toxicity

    1. Threshold and non-threshold effects. For many animal studies, a 
dose response relationship can be determined, which provides a dose 
that causes adverse effects (threshold effects) and doses causing no-
observed effects (the ``no-observed effect level'' or ``NOEL'').
    Once a study has been evaluated and the observed effects have been 
determined to be threshold effects, EPA generally divides the NOEL from 
the study with the lowest NOEL by an uncertainty factor (usually 100 or 
more) to determine the Reference Dose (RfD). The RfD is a level at or 
below which daily aggregate exposure over a lifetime will not pose 
appreciable risks to human health. An uncertainty factor (sometimes 
called a ``safety factor'') of 100 is commonly used since it is assumed 
that people may be up to 10 times more sensitive to pesticides than the 
test animals, and that one person or subgroup of the population (such 
as infants and children) could be up to 10 times more sensitive to a 
pesticide than another. In addition, EPA assesses the potential risks 
to infants and children based on the weight of the evidence of the 
toxicology studies and determines whether an additional uncertainty 
factor is warranted. Thus, an aggregate daily exposure to a pesticide 
residue at or below the RfD (expressed as 100% or less of the RfD) is 
generally considered acceptable by EPA. EPA generally uses the RfD to 
evaluate the chronic risks posed by pesticide exposure. For shorter-
term risks, EPA uses a RfD approach or calculates a margin of exposure 
(MOE) by dividing the estimated human exposure into the NOEL from the 
appropriate animal study. Commonly, EPA finds MOEs lower than 100 to be 
unacceptable. This 100-fold MOE is based on the same rationale as the 
100-fold uncertainty factor.
    Lifetime feeding studies in two species of laboratory animals are 
conducted to screen pesticides for cancer effects. When evidence of 
increased cancer is noted in these studies, the Agency conducts a 
weight of the evidence review of all relevant toxicological data 
including short-term and mutagenicity studies and structure activity 
relationship. Once a pesticide has been classified as a potential-human 
carcinogen, different types of risk assessments (e.g., linear low-dose 
extrapolations or MOE calculation based on the appropriate NOEL) will 
be carried out based on the nature of the carcinogenic response and the 
Agency's knowledge of its mode of action.
    2. Differences in toxic effect due to exposure duration. The 
toxicological effects of a pesticide can vary with different exposure 
durations. EPA considers the entire toxicity data base, and based on 
the effects seen for different durations and routes of exposure, 
determines which risk assessments should be done to assure that the 
public is adequately protected from any pesticide-exposure scenario. 
Both short and long durations of exposure are always considered. 
Typically, risk assessments include ``acute,'' ``short-term,'' 
``intermediate-term,'' and ``chronic'' risks. These assessments are 
defined by the Agency as follows.
    Acute risk, by the Agency's definition, results from 1-day 
consumption of food and water, and reflects toxicity which could be 
expressed following a single-oral exposure to the pesticide residues. 
High-end exposure to food and water residues are typically assumed.
    Short-term risk results from exposure to the pesticide for a period 
of 1-7 days, and therefore overlaps with the acute risk assessment. 
Historically, this risk assessment was intended to address primarily 
dermal and inhalation exposure which could result, for example, from 
residential pesticide applications. However, since enaction of FQPA, 
this assessment has been expanded to include both dietary and non-
dietary sources of exposure, and will typically consider exposure from 
food, water, and residential uses when reliable data are available. In 
this assessment, risks from average food and water exposure, and high-
end residential exposure, are aggregated. High-end exposures from all 
three sources are not typically added because of the very-low 
probability of this occurring in most cases, and because the other 
conservative assumptions built into the assessment assure adequate 
protection of public health. However, for cases in which high-end 
exposure can reasonably be expected from multiple sources (e.g. 
frequent and widespread homeowner use in a specific geographical area), 
multiple high-end risks will be aggregated and presented as part of the 
comprehensive risk assessment/characterization. Since the toxicological 
endpoint considered in this assessment reflects exposure over a period 
of at least 7 days, an additional degree of conservatism is built into 
the assessment; i.e., the risk assessment nominally covers 1-7 days 
exposure, and the toxicological endpoint/NOEL is selected to be 
adequate for at least 7 days of exposure. (Toxicity results at lower 
levels when the dosing duration is increased.)
    Intermediate-term risk results from exposure for 7 days to several 
months. This assessment is handled in a manner similar to the short-
term risk assessment.
    Chronic risk assessment describes risk which could result from 
several months to a lifetime of exposure. For this assessment, risks 
are aggregated considering average exposure from all sources for 
representative population subgroups including infants and children.

B. Aggregate Exposure.

    In examining aggregate exposure, section 408 of the FFDCA requires 
that EPA take into account available and reliable information 
concerning exposure from the pesticide residue in the food in question, 
residues in other foods for which there are tolerances, residues in 
groundwater or surface water that is consumed as drinking water, and 
other non-occupational exposures through pesticide use in gardens, 
lawns, or buildings (residential and other indoor uses). Dietary 
exposure to residues of a pesticide in a food commodity are estimated 
by multiplying the average daily consumption of the food forms of that 
commodity by the tolerance level or the anticipated pesticide residue 
level. The Theoretical Maximum Residue Contribution (TMRC) is an 
estimate of the level of residues consumed daily if each food item 
contained pesticide residues equal to the tolerance. In evaluating food 
exposures, EPA takes into account varying consumption patterns of major 
identifiable subgroups of consumers, including infants and children. 
The TMRC is a ``worst case'' estimate since it is based on the 
assumptions that food contains pesticide residues at the tolerance 
level and that 100% of the crop is treated by pesticides that have 
established tolerances. If the TMRC exceeds the RfD or poses a lifetime 
cancer risk that is

[[Page 38485]]

greater than approximately one in a million, EPA attempts to derive a 
more accurate exposure estimate for the pesticide by evaluating 
additional types of information (anticipated residue data and/or 
percent of crop treated data) which show, generally, that pesticide 
residues in most foods when they are eaten are well below established 
tolerances.

II. Aggregate Risk Assessment and Determination of Safety

     The toxicology data base for fipronil has previously been 
evaluated and was considered adequate to support registration for use 
on corn (62 FR 62970) (FRL-5757-4). Since that time, MB46513 has been 
identified. It appears to have greater toxicity than the parent, 
fipronil. MB46513 is not an animal or plant metabolite. Rather, it 
forms when the parent compound fipronil is exposed to sunlight. It is 
not present on corn, but is potentially present on rice due to the 
foliar application (to germinated rice seed).
    Consistent with section 408(b)(2)(D) of the FFDCA, EPA has reviewed 
the available scientific data and other relevant information in support 
of this action, EPA has sufficient data to assess the hazards of 
fipronil and to make a determination on aggregate exposure, consistent 
with section 408(b)(2) of the FFDCA, for tolerances for combined 
residues of fipronil, its metabolites MB46136 and MB45950, and its 
photodegradate MB46513 in or on rice grain at 0.04 ppm and rice straw 
at 0.10 ppm.

A. Toxicology Data Base

     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 fipronil and its 
photodegradate MB46513 are discussed in this unit.
    1. Acute studies--i. Technical fipronil. A battery of acceptable 
acute toxicity studies place technical fipronil in toxicity Categories 
II and III. It is classified as a non-sensitizer.
    ii. Icon 6.2 FS (56% fipronil). A battery of acute toxicity studies 
submitted for Icon 6.2 FS places it in toxicity categories II and III. 
This formulation is classified as a sensitizer.
    iii. MB46513. Based on acute oral and acute dermal studies, MB46513 
is classified in toxicity category I. No studies were submitted for 
acute inhalation, primary eye, primary dermal, and dermal 
sensitization.
    2. Subchronic toxicity testing. The data base for subchronic 
toxicity is considered complete. No additional studies are required at 
this time.
    i. Fipronil. a. An acceptable subchronic oral toxicity feeding 
study in the rat established the lowest observed-effect level (LOEL) to 
be 30 ppm for males (1.93 milligram (mg)/kilogram (kg)/day) and females 
(2.28 mg/kg/day) based on alterations in serum-protein values and 
increased weight of the liver and thyroid. The NOEL was 5 ppm for males 
(0.33 mg/kg/day) and females (0.37 mg/kg/day).
    b. An acceptable subchronic oral toxicity feeding study in the 
mouse established the LOEL at 25 ppm (3.2 and 4.53 mg/kg/day, for males 
and females, respectively) based on a possible decreased body-weight 
gain. The no-observed adverse-effect level (NOAEL) was 10 ppm (1.27 and 
1.72 mg/kg/day, for males and females, respectively). The NOEL is less 
than or equal to 1 ppm (0.13 and 0.17 mg/kg/day for males and females, 
respectively) based on hepatic hypertrophy at all doses.
    c. An acceptable subchronic oral toxicity [capsule] study in the 
dog established that the LOEL is 10.0 mg/kg/day for males (based on 
clinical signs of toxicity) and 2.0 mg/kg/day for females (based on 
clinical signs of toxicity and decreased body-weight gain). The NOEL is 
2.0 mg/kg/day for males and 0.5 mg/kg/day for females.
    d. An acceptable repeated dose dermal study using the rat found 
that the systemic LOEL was 10 mg/kg/day based on decreased body-weight 
gain and food consumption; the dermal irritation LOEL is greater than 
10.0 mg/kg/day. The systemic NOEL was 5.0 mg/kg/day; the dermal 
irritation NOEL was greater than or equal to 10.0 mg/kg/day.
    ii. MB46513. a. An acceptable subchronic oral toxicity feeding 
study using the rat found that the LOEL was 3 ppm (0.177 and 0.210 mg/
kg/day for males and females, respectively) based on the occurrence of 
aggressivity, irritability to touch and increased motor activity in one 
male (these signs are also observed in the mouse). The NOEL was 0.5 ppm 
(0.029 and 0.035 mg/kg/day for males and females, respectively). The 
study demonstrates that the metabolite is more toxic than the parent 
chemical fipronil when administered to rats for 90 days.
    b. An acceptable subchronic oral toxicity feeding study using the 
mouse found that the LOEL is 2 ppm (0.32 mg/kg/day), based on the 
aggressive and irritable behavior with increased motor activity in 
males. The NOEL is 0.5 ppm (0.08 mg/kg/day).
    c. An acceptable subchronic oral toxicity feeding study using the 
dog established that the LOEL is 35 ppm (1.05 mg/kg/day), based on 
behavioral changes in 2 out of 5 females. The NOEL is 9.5 ppm (0.29 mg/
kg/day).
    3. Chronic toxicity studies. The data base for chronic toxicity is 
considered complete. No additional studies are required at this time.
    i. An acceptable chronic feeding study in the rat using fipronil 
found that the LOEL is 1.5 ppm for males (0.059 mg/kg/day) and females 
(0.078 mg/kg/day) based on an increased incidence of clinical signs and 
alterations in clinical chemistry and thyroid parameters. The NOEL is 
0.5 ppm for males (0.019 mg/kg/day) and females (0.025 mg/kg/day). The 
study demonstrated that fipronil is carcinogenic to rats at doses of 
300 ppm in males (12.68 mg/kg/day) and females (16.75 mg/kg/day).
    ii. An acceptable chronic oral toxicity [capsule] study in the dog 
using fipronil established a LOEL at 2.0 mg/kg/day based on clinical 
signs of neurotoxicity and abnormal neurological examinations. The NOEL 
is 0.2 mg/kg/day.
    4. Carcinogenicity studies. The data base for carcinogenicity is 
considered complete. No additional studies are required at this time.
    i. The results of a carcinogenicity study in the rat using fipronil 
is described in Unit II.A.3.i of this preamble.
    ii. A acceptable carcinogenicity [feeding] study in the mouse using 
fipronil found that the LOEL is 10 ppm (1.181 mg/kg/day for males and 
1.230 mg/kg/day for females) based on decreased body-weight gain, 
decreased food conversion efficiency (males), increased liver weights 
and increased incidence of hepatic histopathological changes. The NOEL 
is 0.5 ppm (0.055 mg/kg/day for males and 0.063 mg/kg/day for females). 
The study demonstrated that fipronil is not carcinogenic to CD-1 mice 
when administered at doses of 30 ppm.
    5. Developmental toxicity studies. The data base for developmental 
toxicity is considered complete. No additional studies are required at 
this time.
    i. Fipronil. a. An acceptable prenatal developmental study in the 
rat found that the maternal toxicity LOEL was 20 mg/kg/day based on 
reduced body-weight gain, increased water consumption, reduced food 
consumption, and reduced food efficiency. The maternal toxicity NOEL 
was 4 mg/kg/day. The developmental toxicity LOEL was greater than 20 
mg/

[[Page 38486]]

kg/day. Developmental toxicity NOEL was 20 mg/kg/day or higher.
    b. An acceptable prenatal developmental study in the rabbit found 
that the maternal toxicity LOEL was 0.1 mg/kg/day or lower, based on 
reduced body-weight gain, reduced food consumption and efficiency. 
Maternal toxicity NOEL was less than 0.1 mg/kg/day. The developmental 
toxicity LOEL was greater than 1.0 mg/kg/day. The developmental 
toxicity NOEL was 1.0 mg/kg/day or higher.
    ii. MB46513. An acceptable prenatal developmental study using the 
rat found that the maternal toxicity LOEL was 2.5 mg/kg/day and the 
NOEL was 1.0 mg/kg/day based an increase in clinical signs of toxicity 
(reduced body-weight gain, food consumption and food efficiency). The 
Developmental Toxicity LOEL was 2.5 mg/kg/day and the NOEL was 1.0 mg/
kg/day based on the slight increase in fetal and litter incidence of 
reduced ossification of several bones.
    6. Reproduction toxicity studies. The data base for reproductive 
toxicity is considered complete. No additional studies are required at 
this time.
    An acceptable two-generation reproduction study in the rat using 
fipronil concluded that the LOEL for parental (systemic) toxicity was 
30 ppm (2.54 mg/kg/day for males and 2.74 mg/kg/day for females) based 
on increased weight of the thyroid glands and liver in males and 
females; decreased weight of the pituitary gland in females; and an 
increased incidence of follicular epithelial hypertrophy in the 
females. The NOEL for parental (systemic) toxicity was 3 ppm (0.25 mg/
kg/day for males and 0.27 mg/kg/day for females).
    The LOEL for reproductive toxicity was 300 ppm (26.03 mg/kg/day for 
males and 28.40 mg/kg/day for females) based on clinical signs of 
toxicity in the F1 and F2 offspring; decreased 
litter size in the F1 and F2 litters; decreased 
body weights in the F1 and F2 litters; decrease 
in the percentage of F1 parental animals mating; reduction 
in fertility index in F1 parental animals; reduced post-
implantation survival and offspring postnatal survivability in the F2 
litters; and delay in physical development in the F1 and 
F2 offspring. The NOEL for reproductive toxicity was 30 ppm 
(2.54 mg/kg/day for males and 2.74 mg/kg/day for females).
    7. Neurotoxicity. The data base for neurotoxicity is considered 
complete. No additional studies are required at this time.
    i. Fipronil. a.An acceptable acute neurotoxicity study in the rat 
concluded the following: The NOEL was 0.5 mg/kg for males and females. 
The LOEL was 5.0 mg/kg for males and females based on decreased hind-
leg splay at the 7 hour post-treatment evaluation in males and females.
    b. An acceptable acute neurotoxicity study in the rat concluded 
that the NOEL was 2.5 mg/kg. The LOEL is 7.5 mg/kg, based on decreased 
body-weight gains, food consumption and feed efficiency in females, 
decreased hindlimb splay in males (at 7-hours post test) and decreased 
grooming in females (14-days post test).
    c. An acceptable subchronic neurotoxicity screening battery in the 
rat concluded the LOEL was 150 ppm (8.89 mg/kg/day, males; 10.8 mg/kg/
day, females) based on the results of the functional observational 
battery (FOB); the NOEL was 5.0 ppm (0.301 mg/kg/day, males; 0.351 mg/
kg/day, females).
    d. In a developmental neurotoxicity study, fipronil was 
administered to 30 female rats/group in the diet at dose levels of 0, 
0.5, 10, or 200 ppm (0.05, 0.90, or 15 mg/kg/day, respectively) from 
gestation day 6 to lactation day 10. This study found that the maternal 
LOEL was 200 ppm (15 mg/kg/day), based on decreased body weight, body-
weight gain, and food consumption. The maternal NOEL was 10 ppm (0.90 
mg/kg/day). The developmental toxicity LOEL is 10 ppm (0.9 mg/kg/day), 
based on a marginal but statistically significant decrease in group 
mean pup weights during lactation and significant increase in time of 
preputial separation in males. The NOEL for developmental toxicity is 
0.5 ppm (0.05 mg/kg/day). The developmental neurotoxicity LOEL is 200 
ppm (15 mg/kg/day) based on: Decreased auditory startle response; 
reduced swimming direction scores, group mean angle measurements, and 
water ``Y'' maze times trails; and decreased absolute-brain weights. 
The NOEL for developmental neurotoxicity is 10 ppm (0.90 mg/kg/day).
    It is noted that developmental toxicity occurred at a dose lower 
than the maternal-toxicity NOEL in this study. However, EPA did not 
consider this to indicate increased susceptibility to infants and 
children. See Unit II.F.1.ii.d of this preamble for a detailed 
discussion of this point.
    ii. MB46513. An acceptable acute neurotoxicity study in the rat 
concluded that the neurobehavioral LOEL for rats is 12 mg/kg based on 
decreases in body-weight gains and food consumption for males and 
females during the week following treatment, significant decreases in 
locomotor activity 6-hours post dosing for both males and females, 
decreases in hind-limb splay and rectal temperature at 6-hours post 
dose in males and females, decreases in the proportion of high-dose 
males with an immediate righting reflex on days 7 and 14. Decreased 
forelimb grip strength in males on day 7 and increased forelimb grip 
strength in high-dose females at 6-hours post dosing was possibly 
related to the treatment, because there were also slight increases in 
forelimb grip strength in high-dose males at 6 hours and slight 
decreases in forelimb grip strength in high dose females at 7 days and 
in high-dose males and females at 14 days.. The NOEL is 2 mg/kg.
    8. Mutagenicity. The available studies indicate that fipronil and 
MB46513 are not mutagenic in bacteria and are not clastogenic in vitro 
or in vivo up to doses that showed clear test material interaction with 
the target cells. Based on these considerations, EPA concluded that 
there is no concern for mutagenicity. The submitted test battery for 
both compounds satisfy the new mutagenicity initial testing battery 
guidelines. No further studies are required at this time.
    i. Fipronil. a. An acceptable gene mutation/bacteria test using 
salmonella typhimurium concluded that fipronil was not mutagenic.
    b. An acceptable in vitro gene mutation assay in mammalian cells/
Chinese hamster V79 cells concluded as follows: Fipronil was negative 
for inducing forward gene mutations at the HGPRT locus in cultured 
Chinese hamster V79 cells.
    c. An acceptable cytogenetic in vivo micronucleus assay in the 
mouse concluded as follows: There was no evidence of a clastogenic or 
aneugenic effect at any dose or at any harvest time.
    d. An acceptable cytogenetic assay in human lymphocytes concluded 
as follows: There was no evidence of a clastogenic effect when human 
lymphocytes were exposed in vitro to fipronil.
    ii. MB46513. a. An acceptable gene mutation/bacteria test using 
salmonella typhimurium showed that there was no evidence of a mutagenic 
response at any dose.
    b. An acceptable gene mutation/in vitro assay in mammalian cells 
considering the HPRT locus in Chinese Hamster Ovary (CHO) cells showed 
that MB46513 did not induce forward mutations at the HPRT locus in CHO 
cells at any dose level tested.
    c. An acceptable cytogenetics/in vivo mouse bone marrow 
micronucleus assay showed that there was no significant increase in the 
frequency of MPCEs in bone marrow after any MB46513 treatment time; 
therefore, the test article is considered negative in this micronucleus 
assay.
    9. Metabolism study. The data base for metabolism is considered to 
be

[[Page 38487]]

complete. No additional studies are required at this time.
    i. Fipronil. An acceptable metabolism study in the rat using 14-C 
labeled and unlabeled fipronil showed the following: With oral dosing, 
the rate and extent of absorption appeared similar among all dose 
groups, but may have been decreased at the high dose. There were no 
significant sex-related differences in excretion. Feces appeared to be 
the major route of excretion for fipronil derived radioactivity, where 
45-75% of an administered dose was excreted. Excretion in urine was 
between 5-25%. Major metabolites in urine included two ring-opened 
products of the metabolite MB45897, two oxidation products (MB46136 and 
RPA200766), and the parent chemical. In feces, the parent was detected 
as a significant fraction of the sample radioactivity as well as the 
oxidation product MB46136 and MB45950. Since MB46513 is not an animal 
metabolite but a photodegradate, it was not found in this study.
    ii. MB46513. In a acceptable rat metabolism study, 14C 
labeled MB46513 was administered to rats by gavage as a single dose or 
as a single dose following a 14-day pretreatment with unlabeled 
MB46513. Unchanged MB46513 in urine accounted for less than 0.1% of the 
dose. Fecal excretion of unchanged MB46513 is the principal pathway for 
elimination of MB46513 from rats. The high levels of radioactivity in 
fat compared to blood and the prolonged elimination half-life indicate 
that there is a potential for bioaccumulation of MB46513 in fatty 
tissues.
    10. Dermal absorption--i. Fipronil. An acceptable study using the 
rat found that the quantity of fipronil absorbed was less than 1% at 
all doses. The system was saturated at 3.88 mg/cm2. The 
dermal absorption rat was calculated to be less than 1% at 24 hours.
    ii. MB46513. An acceptable study in the rat using [14C] 
labeled MB46513 found that after 24 hours of exposure, dermal 
absorption of MB46513 was minimal. For all dose groups, the majority of 
the dose was not absorbed (90.2-102.3%), and only trace amounts (equal 
to or less than 0.1%) of radioactivity were excreted in the urine and 
feces. There was 2.35% adhered to the skin and absorbed at the 10 hour 
time point with the lowest dose applied (0.006 mg/cm2).
    11. Special studies--i. Fipronil. a. A supplemental thyroid 
function study in the rat showed the following: The treatment with 
fipronil or Noxyflex appeared to result in stimulation of the thyroid 
glands as evidenced by increased accumulation of 125I in the 
thyroid glands and by increases in the ratios of radioactive 
distribution between the blood and thyroid. These changes were 
accompanied by increases in thyroid weight. Treatment with 
propylthiouracil (PTU) produced decreases in the amount of 
125I incorporated in the thyroid and in the blood: Thyroid 
ratios along with elevated levels of 125I in the blood. 
However, the weights of the thyroids from these animals were increased 
by over 2.5 fold compared to the controls and therefore, the ratio of 
125I in the blood to thyroid weight was reduced. The 
administration of perchlorate produced further reductions in the 
125I content in the thyroids and in the blood: Thyroid 
125I radioactivity ratio. There was no evidence of an 
inhibition of iodide incorporation by either fipronil or noxyflex.
    b. A supplemental thyroxine clearance study in the rat using 
technical fipronil showed the following: Fipronil had no effect on 
mortality or other ante mortem parameters. Phenobarbital-treated 
animals were observed to have collapsed posture, lethargy and shallow 
breathing on the first day of treatment. There was no effect of 
fipronil on clearance after 1 day of treatment. However, after 14 days, 
there was a decrease in terminal half life (52% of control level) and 
increases in clearance and volume of distribution (261% and 137% of 
control level, respectively). The effects seen with phenobarbital 
treatment were similar, although quantitatively not as severe and were 
evident on day one of treatment.
    c. An acceptable 28-day dietary study in the rat concluded that the 
LOEL is 25 ppm or lower (3.4 mg/kg/day in males; 3.5 mg/kg/day in 
females), based on clinical laboratory changes, increased absolute 
liver weights in females and histopathological alterations in the 
thyroid glands. The NOEL is less than 25 ppm.
    ii. MB46513. An acceptable 28-day dietary range-finding study in 
the rat measured thyroid hormone levels as well as standard study 
parameters. It found that the LOEL is 30 ppm (2.20 and 2.32 mg/kg/day 
for males and females, respectively), based on clinical signs including 
piloerection, curling up and thin appearance; and decreased body 
weights in both sexes. The NOEL is 3 ppm (0.23 and 0.24 mg/kg/day for 
males and females, respectively).

B. Toxicology Endpoints

    The toxicology endpoints for fipronil and MB46513 are presented in 
this unit.
    1. Fipronil--i. RfD. The RfD for fipronil is 0.0002 mg/kg/day using 
a NOEL of 0.019 mg/kg/day (0.5 ppm) established from a combined chronic 
toxicity/carcinogenicity study in rats and an uncertainty factor of 
100. The LOEL=1.5 ppm (male (M): 0.059 mg/kg/day; female (F): 0.078 mg/
kg/day), based on an increased incidence of clinical signs (seizures 
and death) and alterations in clinical chemistry (protein) and thyroid 
parameters.
    ii. Carcinogenic classification and risk quantification. EPA has 
classified this chemical as a Group C--Possible Human Carcinogen, based 
on increases in thyroid follicular-cell tumors in both sexes of the 
rat, which were statistically significant by both pair-wise and trend 
analyses. EPA has used the RfD methodology to estimate human risk 
because the thyroid tumors are due to a disruption in the thyroid-
pituitary status. There was no apparent concern for mutagenicity.
    iii. Dermal absorption. The percent absorbed was less than 1% at 24 
hours based on a dermal absorption study.
    iv. Other toxicological endpoints--a. Acute dietary (1 day). In an 
acute neurotoxicity study in rats the NOEL was 2.5 mg/kg/day based on 
decreased body-weight gains, food consumption and feed efficiency in 
females, and decreased hind-limb splay in males at 7-hours post dosing 
at 7.5 mg/kg/day LOEL. Although a developmental neurotoxicity study 
with the parent compound fipronil had a lower NOEL, EPA determined that 
the effects from that study are not attributable to a single exposure 
(dose) and therefore are not appropriate for acute dietary-risk 
assessments.
    b. Short- and intermediate-term residential (dermal). In a 21-day 
dermal study the NOEL was 5 mg/kg/day based on decreased body-weight 
gain and food consumption in male and female rabbits observed at the 
LOEL of 10 mg/kg/day. The dermal NOEL is supported by the oral NOEL of 
0.05 mg/kg/day established in a developmental neurotoxicity study when 
used in conjunction with a dermal absorption factor of 1%. This yields 
an equivalent-dermal dose of 5 mg/kg/day.
    c. Chronic residential (non-cancer). In a combined chronic 
toxicity/carcinogenicity study in the rat, the NOEL is 0.5 ppm (M: 
0.019 mg/kg/day; F: 0.025 mg/kg/day), based on an increased incidence 
of clinical signs (seizures and death) and alterations in clinical 
chemistry (protein) and thyroid parameters (increased TSH, decreased 
T4) at 1.5 ppm (M: 0.059 mg/kg/day; F: 0.078 mg/kg/day). Since the NOEL 
identified is from an oral study, a

[[Page 38488]]

dermal absorption factor of less than 1% was used in risk calculations. 
(This study/dose was also used to establish the chronic RfD).
    2. MB46513--i. RfD. There is no long-term (chronic or 
carcinogenicity) studies are available for MB46513. However, the 
toxicity profile of MB46513 indicate this material to be approximately 
10 times more potent than the parent compound when the NOELs/LOELs are 
compared (with the exception of the acute toxicity tests). See table 1 
in this preamble.

   Table 1.--A Comparison of Toxicities of Photodegradate MB46513 and   
                                Fipronil                                
------------------------------------------------------------------------
                                    Photodegradate                      
              Study                     MB46513            Fipronil     
------------------------------------------------------------------------
Acute Oral......................  LD50= 16 mg/kg      LD50= 92 mg/kg    
Acute Neurotoxicity.............  NOEL/LOEL= 2/12 mg/ NOEL/LOEL= 2.5/7.5
                                   kg                  mg/kg            
                                                      NOEL/LOEL= 0.5/5.0
                                                       mg/kg            
28-Day Oral--Rat................  NOEL/LOEL= 0.23/    NOEL/LOEL= 3.4 mg/
                                   2.2 mg/kg/day       kg/day lowest    
                                                       dose tested (LDT)
90-Day Oral--Mouse..............   NOEL/LOEL= 0.08/    NOEL/LOEL= 1.7/  
                                   0.32 mg/kg/day      3.2 mg/kg/day    
90-Day Oral--Rat................   NOEL/LOEL= 0.029/   NOEL= 0.33/1.9 mg/
                                   0.18 mg/kg/day      kg/day           
Developmental--Rat..............  Maternal NOEL/      Maternal NOEL/    
                                   LOEL= 1/2.5 mg/kg/  LOEL= 4/20 mg/kg/
                                   day                 day              
                                  Developmental NOEL/ Developmental NOEL/
                                   LOEL= 1/2.5 mg/kg/  LOEL= 20 mg/kg/  
                                   day                 day highest dose 
                                                       tested (HDT)     
------------------------------------------------------------------------

     As shown in table 1 of this preamble, the 28-day and 90-day 
subchronic oral studies and oral developmental studies consistently 
demonstrated an approximately 10-fold greater potency of MB46513 as 
compared to the parent compound, fipronil. In the acute oral tests, the 
difference between the LD50 values for MB46513 and fipronil 
is not considered significant due to the insensitivities inherent in 
this test.
    EPA concluded that there is sufficient experimental evidence to 
warrant the application of a 10-fold Potency Adjustment Factor (PAF) to 
the chronic NOEL for the parent compound to calculate a chronic NOEL 
for MB46513 in the absence of test data on the chemical. An adjusted 
NOEL was established at 0.0019 mg/kg/day for MB46513.
    An Uncertainty Factor (UF) of 100 was applied to account for inter 
(10 x)-and intra-(10x) species variation.
    ii. Carcinogenic classification and risk quantification. No 
carcinogenicity studies are available with MB46513. Fipronil, the 
parent compound, was classified as a Group C Carcinogen (Possible Human 
Carcinogen). This classification is based on increased incidence of 
thyroid follicular-cell tumors in rats. EPA used the RfD methodology 
for the quantification of human risk because the thyroid tumors are 
related to a disruption in the thyroid-pituitary status and there was 
no apparent concern for mutagenicity or available information from 
structurally related analogs. EPA has no reason to believe MB46513 is 
more carcinogenic than the parent. EPA determined that it was 
appropriate to use the RfD methodology to quantify chronic risk for 
MB46513. The NOEL used for the chronic RfD has been adjusted by the PAF 
to account for the fact that MB46513 is about 10 times more toxic than 
the parent (except for acute toxicity).
    iii. Dermal absorption. The percent absorbed is estimated at 
approximately 2% at 10 hours based on a dermal absorption study with 
MB46513.
    iv. Other toxicological endpoints--a. Acute dietary. The NOEL is 2 
mg/kg in an acute neurotoxicity study in rats (with MB46513) based on 
significant decreases in locomotor activity in both sexes during the 
first 30 minutes as well as decreases in hind-limb splay and rectal 
temperature in both sexes at 6-hours post dosing at 12 mg/kg/day LOEL. 
Effects were seen on the day of treatment after a single-oral exposure 
(dose) and thus is appropriate for this risk assessment. For reasons 
noted in Unit II.B.1.iv of this preamble, EPA did not use a 
developmental neurotoxicity study with the parent compound fipronil for 
this risk assessment.
    b. Short- and intermediate-term dermal exposure (1 to 7 days) (1 
week to several months). The adjusted dose of 0.5 mg/kg/day was derived 
by dividing the study NOEL of 5 mg/kg/day by the PAF of 10 (5/10= 0.5 
mg/kg/day). The LOEL was based on decreases in body-weight gain and 
food consumption. The dose and endpoint from the 21-day dermal study 
with the parent compound was used for the following reasons:
    (1) A 21-dermal toxicity study with MB46513 is not available.
    (2) There is low potential for risk from dermal exposure due to 
minimal dermal absorption as indicated for both the parent (< 1%) and 
the MB46513 (2%) materials.
    (3) The developmental/developmental neurotoxicity NOEL of 0.05 mg/
kg/day for fipronil (established in the developmental neurotoxicity 
study), adjusted for 1% dermal absorption (DA), results in a comparable 
dermal dose of 5 mg/kg/day (i.e., 0.05 mg/kg/day ' 1% DA= 5 mg/kg/day) 
which essentially is the same as the NOEL for fipronil in the 21-day 
dermal toxicity study.
    Residential exposure to MB46513 is not expected while spraying or 
handling a recently treated pet as these are brief periods usually 
occurring indoors, and MB46513 forms upon exposure to sunlight. Post-
application exposure to the degradate is also not expected due to the 
products reportedly strong affinity to the sebum and epidermis of pets.
    c. Chronic dermal exposure (several months to lifetime). Based on 
the current use pattern for MB46513 (i.e., 1 application/year at 
planting), long-term exposure via the dermal route is not expected. 
Residential exposures are not chronic in nature as label uses for pets 
indicate treatment every 1 to 3 months.
    d. Recommendation for aggregate exposure risk assessments. An 
aggregate systemic (oral) and dermal exposure-risk assessment is not 
appropriate due to differences in the toxicity endpoints observed 
between the oral (neurotoxicity and alterations in clinical chemistry 
and thyroid parameters) and dermal (decreases in body-weight gain and 
food consumption) routes. An aggregate oral and inhalation risk 
assessment is not required due to the lack of exposure potential via 
the inhalation route based on the current use pattern.

C. Exposures and Risks

    1. From food and feed uses. Tolerances have been established (40 
CFR 180.517) for the combined residues of fipronil in or on on corn, 
eggs, meat, milk, and poultry. Risk assessments were conducted by EPA 
to assess dietary exposures and risks from fipronil and MB46513 as 
follows:
    i. Acute dietary risk. An acute dietary risk assessment is required 
for fipronil and its metabolites and degradate. The NOEL of 2.5 mg/kg 
was selected as the endpoint to be used for fipronil, MB46136, MB45950, 
and MB46513. Since MB46513 does not appear to be significantly more 
acutely toxic than the parent, it was incorporated into the acute 
dietary risk evaluation system (DRES) run for rice. If further 
refinements in the acute dietary risk assessment are required in the 
future, a separate DRES run for MB46513 only will be performed.

[[Page 38489]]



                        Table 2.--Acute Risk for Fipronil, its Metabolites, and Degradate                       
----------------------------------------------------------------------------------------------------------------
                                                                           Exposure (mg/kg/                     
            Subgroup                RfD (mg/kg/day)    Level of concern          day)           Percent of RfD  
----------------------------------------------------------------------------------------------------------------
General U.S. Population.........  0.025               100% RfD            0.0018               7                
Infants (< 1 year)..............  0.025               100% RfD            0.003                12               
Children (1-6 years)............  0.025               100% RfD            0.003                12               
Females (13+ years).............  0.025               100% RfD            0.0012               5                
Males (13+ years)...............  0.025               100% RfD            0.0014               6                
----------------------------------------------------------------------------------------------------------------

    EPA does not consider the acute dietary risks to exceed the level 
of concern.
    ii. Chronic dietary risk. A chronic dietary risk assessment is 
required for fipronil, MB46136, and MB45950. The RfD used for the 
chronic dietary analysis for parent fipronil and 2 metabolites is 
0.0002 mg/kg/day. The RfD used for MB46513 is 0.00002 mg/kg/day. The 
analysis evaluates individual food consumption as reported by 
respondents in the United States Department of Agriculture (USDA) 1977-
78 Nationwide Food Consumption Survey (NFCS) and accumulates exposure 
to the chemical for each commodity.
    Chronic DRES for fipronil, MB46136, MB45950, and MB46513 are 
summarized in Table 3 of this preamble. The DRES analysis utilized the 
anticipated residues calculated from field-trial data for all animal, 
corn, and rice commodities. The proposed fipronil uses result in an 
Anticipated Residue Contribution (ARC) that is equivalent to the 
following percent of the RfD:

                                         Table 3.--Chronic dietary risk                                         
----------------------------------------------------------------------------------------------------------------
                                        Fipronil, MB46136, and                                                  
              Subgroups                        MB45950           Photodegradate MB46513           Total         
----------------------------------------------------------------------------------------------------------------
U.S. Population (48 states)..........  4.8%                     1.7%                     6.5%                   
Hispanics............................  6.2%                     2.9%                     8.1%                   
Non-Hispanic Others..................  5.8%                     3.9%                     9.7%                   
Nursing Infants (< 1 year old).......  2.8%                     2.3%                     5.1%                   
Non-Nursing Infants (< 1 year old)...  11.2%                    5.5%                     16.7%                  
Females (13+ years, pregnant)........  3.3%                     1.2%                     4.5%                   
Females (13+ years, nursing).........  4.2%                     1.6%                     5.8%                   
Children (1-6 years old).............  11.4%                    3.8%                     15.2%                  
Children (7-12 years old)............  7.6%                     2.3%                     9.9%                   
Females (20+ years, not pregnant, not  3.0%                     1.2%                     4.2%                   
 nursing).                                                                                                      
----------------------------------------------------------------------------------------------------------------

    EPA does not consider the chronic dietary risk to exceed the level 
of concern.
    Anticipated residues. Section 408(b)(2)(E) of the FFDCA authorizes 
EPA to consider available data and information on the anticipated 
residue levels of pesticide residues in food and the actual levels of 
pesticide chemicals that have been measured in food. If EPA relies on 
such information, EPA must require that data be provided 5 years after 
the tolerance is established, modified, or left in effect, 
demonstrating that the levels in food are not above the levels 
anticipated. Following the initial data submission, EPA is authorized 
to require similar data on a time frame it deems appropriate.
    Percent crop treated. Section 408(b)(2)(F) of the FFDCA states that 
the Agency may use data on the actual percent of food treated for 
assessing chronic dietary risk onl if the Agency can make the following 
findings:
    (1) That the data used are reliable and provide a valid basis to 
show what percentage of the food derived from such crop is likely to 
contain such pesticide residue.
    (2) That the exposure estimate does not underestimate exposue for 
any significant subpopulation group.
    (3) If data are available on pesticide use and food consumption in 
a particular area, the exposure estimate does not understate exposue 
for the population in such area. In addition, the Agency must provide 
for periodic evaluation of any estimates used. To provide for the 
periodic evaluation of the estimate of percent crop treated as required 
by the section 408 (b)(2)(F) of the FFDCA, EPA may require registrants 
to submit data on percent crop treated.
    Anticipated residues, based on average field trial values, and 
percent crop treated information were used to estimate dietary risk for 
the chronic dietary risk assessment. For the acute dietary risk 
assessment, anticipated residues in blended commodities (such as corn 
and rice processed commodities) were used, without the adjustment for 
percent crop treated. However, tolerance level residues were used for 
fat; meat by-products; meat of cattle, goats, hogs, horses, sheep, and 
poultry; and eggs. Since milk is a blended commodity, an anticipated 
residue value was used. As required by the FQPA, EPA will issue a data 
call-in under section 408(f) of the FFDCA to all fipronil registrants 
for data on anticipated residues, to be submitted no later than 5 years 
from the date of issuance of these tolerances.
    The percent of crop treated estimates for fipronil and MB46513 were 
based on an estimate of percent crop treated by existing products used 
to control rice water weevil and chinch bugs. In addition, as set forth 
in 62 FR 62970, market share estimates were used for corn. They were 
based on an estimate of percent crop treated by other insecticides to 
control corn rootworm, wireworm, and corn borer. EPA considers these 
data reliable. A range of estimates are supplied by this data and the 
upper end of this range was used for the exposure assessment. By using 
this upper end estimate of percent crop treated, the Agency is 
reasonably certain that exposure is not underestimated for any 
significant subpopulation. Further, regional consumption information is 
taken into account through EPA's computer-based model for evaluating 
the exposure of significant subpopulations including several regional 
groups. Review of this regional

[[Page 38490]]

data allows the Agency to be reasonably certain that no regional 
population is exposed to residue levels higher than those estimated by 
the Agency.
    To provide for the periodic evaluation of these estimates of 
percent crop treated and to meet the requirement for data on 
anticipated residues, EPA may require fipronil registrants to submit 
data on percent crop treated.
    2. Dietary exposure (drinking water source). EPA does not have 
monitoring data available to perform a quantitative drinking water risk 
assessment for fipronil at this time. Using environmental fate data, 
EPA developed ground and surface water exposure estimates for use on 
corn and rice.
    i. Ground water (tiered assessment). The environmental fate data 
for fipronil indicate a moderate to high persistence and relatively low 
mobility in terrestrial environments. Based on the SCI-GRO model, acute 
drinking water concentrations in shallow ground water on highly 
vulnerable sites are not likely to exceed the values set forth in 
tables 4-7 of this preamble:

      Table 4.--Estimated Ground Water Residues of Fipronil and its     
                               Metabolites                              
------------------------------------------------------------------------
                                    Corn parts per                      
                                     billion (ppb)        Rice (ppb)    
------------------------------------------------------------------------
Fipronil........................  0.055               0.00804           
MB46136.........................  0.001               0.00038           
MB45950.........................  0.00036             0.000685          
------------------------------------------------------------------------
    Total:......................  0.05636             0.009105          
------------------------------------------------------------------------


   Table 5.--Estimated Ground Water Residues of Photodegradate MB46513  
------------------------------------------------------------------------
                                      Corn (ppb)          Rice (ppb)    
------------------------------------------------------------------------
Photodegradate MB46513..........  0.00026             0.004138          
------------------------------------------------------------------------

    Chronic concentrations are not expected to be higher than acute 
values. Highly vulnerable sites are those with low-organic matter, 
coarse textured soils (e.g., sands and loamy sands) and shallow-ground 
water. The fate data for fipronil and its degradates indicate a higher 
potential mobility on coarse-textured soils (sand or loamy sands).
    ii. Surface water (tiered assessment). Based on the environmental 
fate assessment, fipronil, MB46513, MB46136, and MB45950 can 
potentially move into surface waters. Since fipronil is used as an in-
furrow application on field corn, the runoff potential of fipronil 
residues is expected to be lower than for unincorporated surface 
application techniques. Since photodegradation is a major route of 
degradation for fipronil, its dissipation is expected to be dependent 
on physical components of the water (i.e. sediment loading) which 
affect sunlight penetration. The maximum fipronil concentration for 
acute (peak concentration) and chronic (56-day average ) based on the 
Tier 1 GENEEC surface water modeling is shown in the table 6 of this 
preamble:

        Table 6.--Surface Water Concentrations for Fipronil and its Metabolites Based on GENEEC Modeling        
----------------------------------------------------------------------------------------------------------------
                                                   Corn                                    Rice                 
                                 -------------------------------------------------------------------------------
                                      Acute Peak                                                                
                                       Estimated                                                                
                                     Environmental    Chronic 56-day EEC    Acute Peak EEC    Chronic 56-day EEC
                                     Concentration                               (ppb)               (ppb)      
                                         (EEC)                                                                  
----------------------------------------------------------------------------------------------------------------
Fipronil........................  2.05                0.78                1.45                0.40              
MB46136.........................  0.168               0.062               0.061               0.004             
MB45950.........................  0.039               0.019               0.1296              0.013             
----------------------------------------------------------------------------------------------------------------
    Total.......................  2.257               0.861               1.6406              0.417             
----------------------------------------------------------------------------------------------------------------


           Table 7.--Surface Water Concentrations for Photodegradate MB46513 Based on GENEEC Modeling           
----------------------------------------------------------------------------------------------------------------
                                                   Corn                                    Rice                 
                                 -------------------------------------------------------------------------------
                                                                            Acute Peak EEC    Chronic 56-day EEC
                                    Acute Peak EEC    Chronic 56-day EEC         (ppb)               (ppb)      
----------------------------------------------------------------------------------------------------------------
Photodegradate MB46513..........  0.014               0.009               0.359               0.066             
----------------------------------------------------------------------------------------------------------------

    iii. Drinking water risk (acute and chronic). To calculate the 
Drinking Water Level of Concern (DWLOC) for acute exposure relative to 
an acute toxicity endpoint, the acute dietary food exposure (from the 
DRES analysis) was subtracted from acute RfD to obtain the acute 
exposure to fipronil (plus MB45950 and MB46136) in drinking water. To 
calculate the DWLOC for chronic (non-cancer, cancer) exposure relative 
to a chronic toxicity endpoint, the chronic dietary food exposure (from 
DRES) was subtracted from the chronic RfD to obtain the acceptable 
chronic (non-cancer) exposure to fipronil, MB45950, and MB46136 in 
drinking water. DWLOCs were then calculated using default body weights 
and drinking water consumption figures.
    a. Acute risk. EPA has calculated DWLOCs for acute exposure to 
fipronil, MB45950, MB46136, and MB46513 in surface and ground water for 
the U.S. population and children (1-6 yrs ). They are 810 and 220 ppb, 
respectively.
    b. Chronic risk. For chronic (non-cancer) exposure to fipronil 
(plus MB45950 and MB46136) in surface and ground water, the drinking 
water levels of concern are 6.67 and 1.77 ppb for U.S. population and 
children (1-6 years old), respectively.
    c. Maximum and Average concentrations. Estimated maximum 
concentrations of fipronil, MB45950, MB46136, and MB46513 in surface 
and ground water are 2.271 and 0.05662 ppb (with 0.00026 ppb from 
MB46513 included), respectively. The estimated average concentration of 
fipronil, MB45950, and MB46136 in surface water is 0.861 ppb. Chronic 
concentrations in ground water are not expected to be higher than the 
acute concentrations. For the purposes of the screening-level 
assessment, the maximum and average concentrations in

[[Page 38491]]

ground water are not believed to vary significantly.
    The maximum estimated concentrations of fipronil, MB45950, and 
MB46136 in surface and ground water are less than EPA's levels of 
concern for fipronil, MB45950, and MB46136 in drinking water as a 
contribution to acute aggregate exposure.
    The estimated average concentrations of fipronil, MB45950, and 
MB46136 in surface and ground water are less than EPA's levels of 
concern for fipronil, MB45950, and MB46136 in drinking water as a 
contribution to chronic aggregate exposure. Therefore, taking into 
account the present uses and uses proposed in this action, EPA 
concludes with reasonable certainty that residues of fipronil, MB45950, 
and MB46136 in drinking water (when considered along with other sources 
of exposure for which EPA has reliable data) would not result in 
unacceptable levels of aggregate human health risk at this time.
    d. MB46513 (chronic only). For chronic (non-cancer) exposure to 
MB46513 in surface and ground water, the drinking water levels of 
concern are 0.69 and 0.19 ppb for U.S. population, children (non-
nursing infants, < 1 year old), respectively. To calculate the DWLOC 
for chronic (non-cancer, cancer) exposure relative to a chronic 
toxicity endpoint, the chronic dietary food exposure (from DRES) was 
subtracted from the RfD to obtain the acceptable chronic (non-cancer) 
exposure to MB46513 in drinking water. DWLOCs were then calculated 
using default body weights and drinking water consumption figures.
    Estimated maximum concentrations of MB46513 in ground water is 
0.00026 ppb. The estimated average concentration of MB46513 in surface 
water is 0.009 ppb. Chronic concentrations in ground water are not 
expected to be higher than the acute concentrations. For the purposes 
of the screening-level assessment, the maximum and average 
concentrations in ground water are not believed to vary significantly. 
The estimated average concentrations of MB46513 in surface and ground 
water are less than EPA's levels of concern for MB46513 in drinking 
water as a contribution to chronic aggregate exposure. Therefore, 
taking into account the present uses and uses proposed in this action, 
EPA concludes with reasonable certainty that residues of MB46513 in 
drinking water (when considered along with other sources of exposure 
for which EPA has reliable data) would not result in unacceptable 
levels of aggregate human health risk at this time.
    3. From non-dietary exposure. The residential uses of fipronil 
include the use of ant and cockroach bait traps ranging from 0.01 to 
0.05 percent active ingredient. In addition, three fipronil products 
are registered to control fleas and ticks on dogs and cats. These 
products are applied to the fur of the animal as a ready-to-use pump 
spray or as a ready-to-use, pour-on, spot treatment made along the back 
of the animal between the shoulder blades.
    i. Ant and roach baits. Exposure from the use of fipronil in self 
contained bait stations is expected to result in low exposures since 
there is no contact with the pesticide.
    ii. Pet care. For purposes of setting a tolerance, an aggregate 
short-term and intermediate-term systemic (oral) and dermal exposure 
risk assessment which includes the pet care products is not appropriate 
due to differences in the toxicity endpoints observed between the oral 
(neurotoxicity and alterations in clinical chemistry and thyroid 
parameters) and dermal (decreases in body-weight gain and food 
consumption) routes. Further, though fipronil is currently registered 
for residential uses, no chronic residential exposure is anticipated.
    4. Cumulative exposure to substances with common mechanism of 
toxicity. Fipronil is structurally similar to other members of the 
pyrazole class of pesticides (i.e., tebufenpyrad, pyrazolynate, 
benzofenap, etc.). Further, other pesticides may have common toxicity 
endpoints with fipronil.
    Section 408(b)(2)(D)(v) of the FFDCA requires that, when 
considering whether to establish, modify, or revoke a tolerance, the 
Agency consider ``available information'' concerning the cumulative 
effects of a particular pesticide's residues and ``other substances 
that have a common mechanism of toxicity.'' The Agency believes that 
``available information'' in this context might include not only 
toxicity, chemistry, and exposure data, but also scientific policies 
and methodologies for understanding common mechanisms of toxicity and 
conducting cumulative risk assessments. For most pesticides, although 
the Agency has some information in its files that may turn out to be 
helpful in eventually determining whether a pesticide shares a common 
mechanism of toxicity with any other substances, EPA does not at this 
time have the methodologies to resolve the complex scientific issues 
concerning common mechanism of toxicity in a meaningful way. EPA has 
begun a pilot process to study this issue further through the 
examination of particular classes of pesticides. The Agency hopes that 
the results of this pilot process will increase the Agency's scientific 
understanding of this question such that EPA will be able to develop 
and apply scientific principles for better determining which chemicals 
have a common mechanism of toxicity and evaluating the cumulative 
effects of such chemicals. The Agency anticipates, however, that even 
as its understanding of the science of common mechanisms increases, 
decisions on specific classes of chemicals will be heavily dependent on 
chemical specific data, much of which may not be presently available.
    Although at present the Agency does not know how to apply the 
information in its files concerning common mechanism issues to most 
risk assessments, there are pesticides as to which the common mechanism 
issues can be resolved. These pesticides include pesticides that are 
toxicologically dissimilar to existing chemical substances (in which 
case the Agency can conclude that it is unlikely that a pesticide 
shares a common mechanism of activity with other substances) and 
pesticides that produce a common toxic metabolite (in which case common 
mechanism of activity will be assumed).
    EPA does not have, at this time, available data to determine 
whether fipronil 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, 
fipronil 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 fipronil has a common mechanism of toxicity 
with other substances.
    5. Endocrine disruption. EPA is required to develop a screening 
program to determine whether certain substances (including all 
pesticides and inerts) ``may have an effect in humans that is similar 
to an effect produced by a naturally occurring estrogen, or such other 
endocrine effect...''. The Agency is currently working with interested 
stakeholders, including other government agencies, public interest 
groups, industry, and research scientists in developing a screening and 
testing program and a priority setting scheme to implement this 
program. Congress has allowed 3 years from the passage of FQPA (August 
3, 1999) to implement this program. At that time, EPA may require 
further testing of this active

[[Page 38492]]

ingredient and end use products for endocrine disrupter effects.

D. Aggregate Risks and Determination of Safety for U.S. Population

    1. Acute aggregate exposure and risk. Using refined exposure 
assumptions (anticipated residues for blended commodities), a high-end 
exposure estimate (food only) was calculated for these subgroups: 
females 13+ years, for the general U.S. population, infants (< 1 year), 
children (1-6 years), and males 13+. These risk estimates are the same 
as those displayed in table 2 of this preamble.
    The maximum estimated concentrations of fipronil in surface and 
ground water are less than EPA's levels of concern for fipronil in 
drinking water as a contribution to acute aggregate exposure.
    2. Short- and intermediate-term aggregate exposure and risk. An 
aggregate systemic (oral) and dermal exposure risk assessment is not 
appropriate due to differences in the toxicity endpoints observed 
between the oral (neurotoxicity and alterations in clinical chemistry 
and thyroid parameters) and dermal (decreases in body-weight gain and 
food consumption) routes.
    3. Chronic aggregate exposure and risk. Chronic dietary exposure 
estimates for fipronil, MB46136, MB45950, and MB46513 utilized 
anticipated residues and a projected market share and are thus highly 
refined. For the U.S. population, 6.5% of the RfD is occupied by 
dietary (food) exposure. Though fipronil is currently registered for 
residential uses, no chronic residential exposure is anticipated. The 
estimated average concentrations of fipronil in surface and ground 
water are less than EPA's levels of concern for fipronil in drinking 
water as a contribution to chronic aggregate exposure.
    4. Aggregate cancer risk for U.S. population. For fipronil plus 
MB46136 and MB45950, EPA finds that the dietary risk concerns due to 
long-term consumption of fipronil residues are adequately addressed by 
the DRES chronic exposure analysis using the RfD. For MB46513, EPA 
finds that the dietary risk concerns due to long-term consumption of 
MB46513 residues are adequately addressed by the DRES chronic exposure 
analysis using the RfD.
    5. Safety finding. Based on Unit II.C. of this preamble, EPA 
concludes that there is a reasonable certainty of no harm from 
aggregate exposure to fipronil.

F. Aggregate Risks and Determination of Safety for Infants and Children

    1. Safety factor for infants and children--i. In general. In 
assessing the potential for additional sensitivity of infants and 
children to residues of fipronil, EPA considered data from 
developmental toxicity studies in the rat and rabbit, a two-generation 
reproduction study in the rat, and a developmental neurotoxicity study 
in the rat. The developmental toxicity studies are designed to evaluate 
adverse effects on the developing organism resulting from pesticide 
exposure during prenatal development to one or both parents. 
Reproduction studies provide information relating to effects from 
exposure to the pesticide on the reproductive capability of mating 
animals and data on systemic toxicity. Growth, survival and general 
toxicity are evaluated for two generations of offspring. Developmental 
Neurotoxicity studies are designed to evaluate adverse effects on the 
nervous system of the developing organism resulting from pesticide 
exposure of the pregnant and nursing mother during several critical 
stages of prenatal and postnatal development.
    Section 408 of the FFDCA provides that EPA shall apply an 
additional 10-fold margin of safety for infants and children in the 
case of threshold effects to account for pre-and post-natal toxicity 
and the completeness of the database 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 MOE analysis or through using uncertainty 
(safety) factors in calculating a dose level that poses no appreciable 
risk to humans. EPA believes that reliable data support using the 
standard MOE and uncertainty factor (usually 100 for combined inter- 
and intra-species variability)) and not the additional tenfold MOE/
uncertainty factor when EPA has a complete data base under existing 
guidelines and when the severity of the effect in infants or children 
or the potency or unusual toxic properties of a compound do not raise 
concerns regarding the adequacy of the standard MOE/safety factor.
    ii. Data on Susceptibility--a. Neurotoxicity. Fipronil has 
demonstrated neurotoxicity in the acute and subchronic rat 
neurotoxicity studies as well as in the rat chronic/oncogenicity and 
chronic dog studies.
    b. Developmental toxicity. There are acceptable rat and rabbit 
developmental toxicity studies with fipronil. There is no evidence of 
developmental toxicity in either study. EPA also considered a 
developmental study conducted for MB46513. In that study, pregnant rats 
received oral administration of MB46513 (99.2%). For maternal toxicity, 
the NOEL was 1.0 mg/kg/day and the LOEL was 2.5 mg/kg/day based on an 
increase in clinical signs of toxicity (hair loss) and on reduced body-
weight gain, food consumption, and food efficiency. For developmental 
toxicity, the NOEL was 1.0 mg/kg/day and the LOEL was 2.5 mg/kg/day 
based on a slight increase in fetal and litter incidence of reduced 
ossification of several bones (hyoid, 5th/6th sternebrae, 1st thoracic 
vertebral body, pubic bone, and one or two metatarsi). Most of the 
reduced ossification is weak evidence of a developmental effect. 
Although the minor decrement in fetal weight at 2.5 mg/kg/day has 
questionable biological relevance, the decrement is supported by the 
delayed ossification.
    c. Reproductive toxicity. There is an acceptable two-generation 
reproduction study in the rat with fipronil. Toxicity to the offspring 
(clinical signs of toxicity, decreased litter size, decreased body 
weights, decreased pre- and postnatal survival, and delays in physical 
development.) occurred only at levels where there was maternal toxicity 
(including maternal mortality).
    d. Developmental neurotoxicity. In an acceptable study with 
fipronil, developmental neurotoxicity (behavioral changes and decreased 
absolute brain weights) was seen only at levels where there was 
maternal toxicity (decreased body weight, body-weight gain and food 
consumption). However, developmental toxicity (including marginal but 
statistically significant decrease in group mean pup weights during 
lactation, and significant increase in time of preputial separation in 
males) was seen at levels below levels of maternal toxicity.
    e. Adequacy of data. An acceptable two-generation reproduction 
study in rats and acceptable prenatal developmental toxicity studies in 
rats and rabbits have been submitted to the Agency, meeting basic data 
requirements, as defined for a food-use chemical. In addition, an 
acceptable developmental neurotoxicity study was conducted with 
fipronil and reviewed by the Agency. Further, EPA has a developmental 
toxicity study for MB46513. Where specific data on MB46513 are not 
available, the toxicity of the photodegradate can be reliably estimated 
by comparing the fipronil and MB46513 data bases and taking into 
consideration the PAF. Therefore, additional data on MB46513 are not 
required at this time. There are no data

[[Page 38493]]

gaps for the assessment of the effects of fipronil on developing 
animals following in utero and/or early postnatal exposure.
    f. Determination of susceptibility. Although there is no evidence 
of enhanced pre or post natal susceptibility in infants and children in 
the developmental and reproduction studies for fipronil and MB46513, 
the developmental neurotoxicity study for fipronil identified a 
developmental NOEL (0.05 mg/kg/day) which is less than the maternal 
NOEL of 0.9 mg/kg/day indicating an apparent susceptibility issue. 
However, EPA determined that the evidence regarding susceptibility was 
not convincing due to the equivocal nature of the findings. Of 
principal importance were the following conclusions:
    (1) The effects observed in the offspring at the LOEL of 0.9 mg/kg/
day, although statistically significant, were marginal and appeared to 
define a threshold response level for this study.
    (2) The body weight findings of this study are not supported by 
results of the two-generation reproduction study in rats at similar 
treatment levels.
    EPA concluded that the apparent increased susceptibility in the 
developmental neurotoxicity study was not supported by the overall 
weight-of-the-evidence (including no evidence for increased 
susceptibility in the developmental and reproduction studies) from the 
fipronil data base.
    iii. Determination of the FQPA safety factor. There is a complete 
toxicity data base for fipronil and exposure data is complete or is 
estimated based on data that reasonably accounts for potential 
exposures. Further, as discussed in Unit II.F.1.f of this preamble, EPA 
has concluded that the studies do not show that there is an increased 
susceptibility for developmental effects. Accordingly, EPA believes 
reliable data are available to remove the additional 10-fold safety 
factor for the protection of infants and children.
    2. Acute risk. The total dietary (food only) percents of the acute 
RfD for these population subgroups females 13+ years, for the general 
U.S. population, infants (< 1 year), children (1-6 years), and males 
13+ ranged from 6-12%. This calculation was based on an acute 
neurotoxicity study NOEL in rats of 2.5 mg/kg/day for fipronil and 2.0 
mg/kg/day for MB46513. Despite the potential for exposure to fipronil 
in drinking water, EPA does not expect the acute aggregate exposure to 
exceed EPA's level of concern. The small percent of the acute dietary 
RfD calculated for females 13+ years old provides assurance that there 
is a reasonable certainty of no harm for both females 13+ years and the 
pre-natal development of infants.
    3. Chronic risk. EPA has concluded that the percentage of the RfD 
that will be utilized by chronic dietary (food only) exposure to 
residues of fipronil ranges from 5.1% for nursing infants less than 1 
year old, up to 16.7% for non-nursing infants less than 1 year old. 
Despite the potential for exposure to fipronil in drinking water, EPA 
does not expect the chronic aggregate exposure to exceed 100% of the 
RfD. There are uses of fipronil that result in residential exposure, 
but is not expected to result in chronic exposure. EPA concludes that 
there is a reasonable certainty that no harm will result to infants and 
children from acute, short- and intermediate-term, or chronic aggregate 
exposure to fipronil residues. That data call-in [will] require such 
data to be submitted every 5 years as long as the tolerances remain in 
force.

III. Other Considerations

A. Metabolism In Plants and Animals

    1. Rhone Poulenc AG, Inc. has submitted data from a study 
investigating the metabolism of fipronil in rice. The qualitative 
nature of the residue in rice is adequately understood based on this 
metabolism study. Fipronil was detected in all rice commodities. 
MB46513 was also detected in all commodities. MB45950 and MB46136, 
among other metabolites, were also identified. EPA determined that the 
fipronil residues of concern for the tolerance expression and dietary 
risk assessment in plants animals are the parent and its metabolites 
MB46136 and MB45950 and photodegradate MB46513. The Agency, therefore, 
has determined that the residues of concern for the proposed tolerances 
are fipronil, MB45950, MB46136, and MB46513.
    2. Residues in eggs, meat, milk, and poultry. Rice bran, grain, 
hulls, and straws are animal feed items.
    i. Fipronil. The maximum theoretical dietary burden of fipronil to 
beef and dairy cattle, based on the required tolerances of 0.04 ppm for 
rice and 0.10 ppm for rice straw, is 0.04 ppm. The maximum theoretical 
dietary burden of fipronil to poultry, based on the proposed tolerances 
of 0.04 ppm for rice and 0.10 ppm for rice straw, is 0.04 ppm. 
Acceptable cow and poultry feeding studies were submitted and reviewed 
in conjunction with the pesticide petition for corn. Based on these 
studies, the Agency has already established appropriate tolerance 
levels for fipronil residues in/on animal commodities.
    ii. MB46513. Based on low potential for residues in eggs, meat, and 
milk, EPA will not require animal feeding studies to be conducted with 
MB46513.

B. Analytical Enforcement Methodology

    1. Plants. In conjunction with the cotton petition, gas 
chromatography/electron capture detector (GC/ECD) method EC-95-303 has 
been proposed for enforcement of tolerances for residues of fipronil 
and its metabolites MB45950, MB46136, and photodegradate MB46513, and 
RPA200766 in/on plant commodities. The GC methods used for the analyses 
of samples collected from the rice crop field trials and processing 
study analyze for each compound separately and are adequate for 
collection of residue data. Adequate method validation and concurrent 
method recovery have been submitted for these methods. These methods 
are similar to the GC method proposed for cottonseed which has 
undergone a successful pesticide method validation (PMV). The 
registrant has been notified that all directions pertaining to 
RPA200766 should also be removed as this metabolite has been determined 
to not be of regulatory concern.
    2. Animals. A method for the determination of residues of fipronil, 
MB45950, and MB46136 in animal commodities was previously reviewed in 
conjunction with a petition for corn and animal raw agricultural 
commodities (RACs), and has undergone a successful PMV.
    3. Multiresidue methods. A report on multiresidue testing of 
fipronil, MB45950, and MB46136 has been received and forwarded to the 
Food and Drug Administration (FDA). Acceptable recoveries of fipronil, 
MB45950, and MB46136 were obtained in corn grain. A report on 
multiresidue testing of MB46513 has been received and forwarded to FDA. 
Acceptable recoveries of MB46513 were obtained in corn forage and 
cottonseed.

C. Magnitude of Residues

    1. Plants. The submitted data indicate that the combined residues 
of fipronil, MB45950, MB46136, and MB46513 will not exceed the proposed 
tolerance for rice straw (0.10 ppm), or the proposed tolerance for rice 
grain (0.04 ppm) in/on samples harvested at maturity following either a 
preplant incorporated (PPI) broadcast application of the 80% water 
dispersable granular (WDG) formulation or seed treatment with a 10% 
liquid formulation at about 0.05 lb active ingredient (ai)/acre (A) (1 
x the proposed maximum rate).

[[Page 38494]]

    Based on the highest residue value obtained from samples harvested 
following the proposed PPI or seed treatments at the proposed maximum 
use rate, the proposed tolerance level of 0.10 ppm for rice straw is 
appropriate. No residues of fipronil or MB46136, MB45950, or MB46513 
were detected in rice grain, so the proposed tolerance level for rice 
grain at the combined limits of quantitation for fipronil, MB46136, 
MB45950, and MB46513 (0.04 ppm) is appropriate.
    2. Processed food/feed. Rhone Poulenc AG, Inc. submitted data 
depicting the potential for concentration of fipronil residues in the 
processed commodities of rice. The submitted rice processing data are 
adequate. The data indicate that total residues of fipronil, MB45950, 
MB46136, and MB46513, and RPA200766 are less than the limit of 
quantitation (LOQ) (0.01 ppm) in/on rice grain harvested at maturity 
following PPI broadcast application of the 80% Because treatment at 5-6 
x the label application rate did not result in quantifiable levels of 
fipronil residues of concern in rice grain, all further requirements 
for the processing study are waived, and no tolerances are required for 
the processed commodities of rice. As a result of this use, residues of 
fipronil are not expected to exceed the proposed or existing 
tolerances.

D. International Residue Limits

    There are no CODEX, Canadian, or Mexican MRLs established for 
fipronil in/on rice RACs. Therefore, no compatibility problems exist.

E. Rotational Crop Restrictions

    An acceptable confined rotational crop study with grain, grain 
sorghum, lettuce, radishes, and wheat was submitted and reviewed in 
conjunction with the corn petition.
    The rotational crop restrictions specified on the labels (1 month 
for leafy vegetables, 5 months for root crops, and 12 months for small 
grains and all other crops) are supported by the results of the 
confined rotational crop study.

IV. Conclusion

    Therefore, the tolerances established at 40 CFR 180.517 are amended 
to include combined residues of the insecticide fipronil, MB46136, 
MB45950, and MB46513 in or on rice grain at 0.04 ppm and rice straw at 
0.10 ppm.

V. Objections and Hearing Requests.

    The new FFDCA section 408(g) provides essentially the same process 
for persons to ``object'' to a tolerance regulation issued by EPA under 
new section 408(e) and (l)(6) as was provided in the old section 408 
and in section 409. However, the period for filing objections is 60 
days, rather than 30 days. EPA currently has procedural regulations 
which govern the submission of objections and hearing requests. These 
regulations will require some modification to reflect the new law. 
However, until those modifications can be made, EPA will continue to 
use those procedural regulations with appropriate adjustments to 
reflect the new law.
    Any person may, by September 15, 1998, file written objections to 
any aspect of this regulation and may also request a hearing on those 
objections. Objections and hearing requests must be filed with the 
Hearing Clerk, at the address given above (40 CFR 178.20). A copy of 
the objections and/or hearing requests filed with the Hearing Clerk 
should be submitted to the OPP docket for this rulemaking. The 
objections submitted must specify the provisions of the regulation 
deemed objectionable and the grounds for the objections (40 CFR 
178.25). Each objection must be accompanied by the fee prescribed by 40 
CFR 180.33. If a hearing is requested, the objections must include a 
statement of the factual issues on which a hearing is requested, the 
requestor's contentions on such issues, and a summary of any evidence 
relied upon by the requestor (40 CFR 178.27). A request for a hearing 
will be granted if the Administrator determines that the material 
submitted shows the following: There is 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 in the manner sought by the requestor would be adequate 
to justify the action requested (40 CFR 178.32). 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.

VI. Public Record

    EPA has established a record for this rulemaking under docket 
control number OPP-300612 (including any comments and data submitted 
electronically). A public version of this record, including printed, 
paper versions of electronic comments, which does not include any 
information claimed as CBI, is available for inspection from 8:30 a.m. 
to 4 p.m., Monday through Friday, excluding legal holidays. The public 
record is located in room 119 of the Public Information and Records 
Integrity Branch, Information Resources and Services Division (7502C), 
Office of Pesticide Programs, Environmental Protection Agency, Crystal 
Mall 2, 1921 Jefferson Davis Hwy., Arlington, VA.
    Electronic comments may be sent directly to EPA at:
    [email protected].

    Electronic comments must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption.
    The official record for this rulemaking, as well as the public 
version, as described above will be kept in paper form. Accordingly, 
EPA will transfer any copies of objections and hearing requests 
received electronically into printed, paper form as they are received 
and will place the paper copies in the official rulemaking record which 
will also include all comments submitted directly in writing. The 
official rulemaking record is the paper record maintained at the 
Virginia address in ADDRESSES at the beginning of this document.

VII. Regulatory Assessment Requirements

    This final rule establishes tolerances 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) (Pub. L. 104-4). Nor does 
it require any prior consultation as specified by Executive Order 
12875, entitled Enhancing the Intergovernmental Partnership (58 FR 
58093, October 28, 1993), or special considerations as required by 
Executive Order 12898, entitled Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations (59 FR 7629, February 16,

[[Page 38495]]

1994), or require OMB review in accordance with Executive Order 13045, 
entitled Protection of Children from Environmental Health Risks and 
Safety Risks (62 FR 19885, April 23, 1997).
    In addition, since these tolerances and exemptions that are 
established on the basis of a petition under FFDCA section 408(d), such 
as the tolerances 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. Nevertheless, the Agency has 
previously assessed whether establishing tolerances, exemptions from 
tolerances, raising tolerance levels or expanding exemptions might 
adversely impact small entities and concluded, as a generic matter, 
that there is no adverse economic impact. The factual basis for the 
Agency's generic certification for tolerance actions published on May 
4, 1981 (46 FR 24950) and was provided to the Chief Counsel for 
Advocacy of the Small Business Administration.

VIII. Submission to Congress and the General Accounting Office

    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 the rule in the Federal Register. This 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: July 2, 1998.
Peter Caulkins,
Acting 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. 346a and 371.

    2. In Sec. 180.517 by revising the introductory text of paragraph 
(a) and adding the following entries to the table in paragraph (a) to 
read as follows:


Sec. 180.517  Fipronil; tolerances for residues.

    (a) General. Therefore, tolerances are established for combined 
residues of the insecticide fipronil (5-amino-1-[2,6-dichloro-4-
(trifluoromethyl)phenyl]-4-[(1R,S)-(trifluoromethyl)sulfinyl]-1H-
pyrazole-3-carbonitrile) and its metabolites 5-amino-1-[2,6-dichloro-4-
(trifluoromethyl)phenyl]-4-[(trifluoromethyl) sulfonyl]-1H-pyrazole-3-
carbonitrile and 5-amino-1-[2,6-dichloro-4-(trifluoromethyl) phenyl]-4-
[(trifluoromethyl)thio]-1H-pyrazole-3-carbonitrile and its 
photodegradate 5-amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl]-4-
[(1R,S)-(trifluoromethyl)]-1H-pyrazole-3-carbonitrile in or on the 
following items at the levels specified:

                                                                        
------------------------------------------------------------------------
                 Commodity                     Parts per million (ppm)  
------------------------------------------------------------------------
                                                                        
          *            *            *            *            *         
Rice grain................................  0.04                        
Rice straw................................  0.10                        
------------------------------------------------------------------------

*    *    *    *    *

[FR Doc. 98-18987 Filed 7-16-98; 8:45 am]
BILLING CODE 6560-50-F