PMEP Home Page --> Pesticide Active Ingredient Information --> Insecticides and Miticides --> fenitrothion (Sumithion) to methyl parathion --> fipronil --> fipronil Pesticide Tolerance 7/98

fipronil Pesticide Tolerance 7/98


[Federal Register: July 17, 1998 (Volume 63, Number 137)]
[Rules and Regulations]
[Page 38483-38495]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17jy98-16]

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

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.

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

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: opp-docket@epa.gov. 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:
sibold.ann@epa.gov.

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 <greek-i>2, 1921 Jefferson Davis Hwy., Arlington, VA.
    Electronic comments may be sent directly to EPA at:
    opp-docket@epamail.epa.gov.

    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