Bifenthrin - Pesticide Tolerance Filing 9/98
[Federal Register: October 7, 1998 (Volume 63, Number 194)]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
ENVIRONMENTAL PROTECTION AGENCY
Notice of Filing of Pesticide Tolerance Petitions
AGENCY: Environmental Protection Agency (EPA).
SUMMARY: This notice announces the initial filing of pesticide
petitions proposing the establishment of regulations for residues of
certain pesticide chemicals in or on various food commodities.
DATES: Comments, identified by the docket control number PF-831, must
be received on or before November 6, 1998.
ADDRESSES: By mail submit written comments to: Public Information and
Records Integrity Branch, Information Resources and Services Divison
(7502C), Office of Pesticides Programs, Environmental Protection
Agency, 401 M St., SW., Washington, DC 20460. In person bring comments
to: Rm. 119, Crystal Mall (CM) #2, 1921 Jefferson Davis Highway,
Comments and data may also be submitted electronically by following
the instructions under "SUPPLEMENTARY INFORMATION." No Confidential
Business Information (CBI) should be submitted through e-mail.
Information submitted as a comment concerning this document may be
claimed confidential by marking any part or all of that information as
CBI. CBI should not be submitted through e-mail. Information marked as
CBI will not be disclosed except in accordance with procedures set
forth in 40 CFR part 2. A copy of the comment 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. All written comments will be available for public inspection in
Rm. 119 at the address given above, from 8:30 a.m. to 4 p.m., Monday
through Friday, excluding legal holidays.
FOR FURTHER INFORMATION CONTACT: The product manager listed in the
Product Manager telephone number Address
Leonard Cole.................. Rm. 209, CM #2, 703- 1921 Jefferson
305-5412; e-mail: Davis Hwy,
cole.leonard@epamail. Arlington, VA
Mark Dow...................... Rm. 214, CM #2, 703- Do.
James Tompkins................ Rm. 239, CM #2, 703 Do.
SUPPLEMENTARY INFORMATION: EPA has received pesticide petitions as
follows proposing the establishment of regulations for residues of
certain pesticide chemicals in or on various raw food commodities under
section 408 of the Federal Food, Drug, and Comestic Act (FFDCA), 21
U.S.C. 346a. EPA has determined that these petitions contain data or
information regarding the elements set forth in section 408(d)(2);
however, EPA has not fully evaluated the sufficiency of the submitted
data at this time or whether the data supports grantinig of the
petition. Additional data may be needed before EPA rules on the
The official record for this notice, as well as the public version,
has been established for this notice of filing under document control
number PF-831 (including comments and data submitted electronically as
described below). 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
official record is located at the address in "ADDRESSES".
Electronic comments can be sent directly to EPA at:
Electronic comments must be submitted as an ASCII file avoiding the
use of special characters and any form of encryption. Comment and data
will also be accepted on disks in Wordperfect 5.1/6.1 file format or
ASCII file format. All comments and data in electronic form must be
identified by the document control number (PF-831) and appropriate
petition number. Electronic comments on this notice may be filed online
at many Federal Depository Libraries.
Authority: 21 U.S.C. 346a.
List of Subjects
Environmental protection, Agricultural commodities, Food additives,
Feed additives, Pesticides and pests, Reporting and recordkeeping
Dated: September 29, 1998.
Director, Registration Division, Office of Pesticide Programs.
Summaries of Petitions
Below summaries of the pesticide petitions are printed. The
summaries of the petitions were prepared by the petitioners. The
petition summary announces the availability of a description of the
analytical methods available to EPA for the detection and measurement
of the pesticide chemical residues or an explanation of why no such
method is needed.
1. FMC Corporation
EPA has received a pesticide petition (PP 8F5014) from FMC
Corporation, 1735 Market Street, Philadelphia, PA 19103 proposing
pursuant to section 408(d) of the Federal Food, Drug and Cosmetic Act,
21 U.S.C. 346a(d), to amend 40 CFR part 180 by establishing a tolerance
for residues of Bifenthrin: (2-methyl [1,1'-biphenyl]-3-yl)methyl 3-(2-
in or on the raw agricultural commodity corn, grain (sweet) at 0.05 and
corn, forage at 3.0 parts per million (ppm). EPA has determined that
the petition contains data or information regarding the elements set
forth in section 408(d)(2) of the FFDCA; however, EPA has not fully
evaluated the sufficiency of the submitted data at this time or whether
the data supports granting of the petition. Additional data may be
needed before EPA rules on the petition.
A. Residue Chemistry
1. Plant metabolism. The metabolism of bifenthrin in plants is
adequately understood. Studies have been conducted to delineate the
metabolism of radiolabelled bifenthrin in various crops all showing
similar results. The residue of concern is the parent compound only.
2. Analytical method. There is a practical method for detecting and
measuring levels of bifenthrin in or on food with a limit of detection
that allows monitoring of food with residues at or above the levels set
in these tolerances (Gas Chromatography with Electron Capture Detection
(GC/ECD) analytical method P-2132M, PP 0E3921, MRID 41658601).
3. Magnitude of residues. Field residue trials meeting EPA study
requirements have been conducted at the maximum label rate for the crop
sweet corn. Results from these trials demonstrate that the proposed
bifenthrin tolerances on corn, sweet (k+cwhr) at 0.05 ppm and on corn,
forage at 3.0 ppm will not be exceeded when the product is applied
following the proposed use directions.
B. Toxicological Profile
1. Acute toxicity. For the purposes of assessing acute dietary
risk, FMC has used the maternal No-Observed-Adverse-Effects-Level
(NOAEL) of 1.0 milligram/kilogram/day (mg/kg/day) from the oral
developmental toxicity study in rats. The maternal Lowest Effect Level
(LEL) of this study of 2.0 mg/kg/day was based on tremors from day 7-17
of dosing. This acute dietary endpoint is used to determine acute
dietary risks to all population subgroups.
2. Genotoxicty. The following genotoxicity tests were all negative:
gene mutation in Salmonella (Ames); chromosomal aberrations in Chinese
hamster ovary and rat bone marrow cells; Hypoxanthine guanine
phophoribosyl transferase (HGPRT) locus mutation in mouse lymphoma
cells; and unscheduled DNA synthesis in rat hepatocytes.
3. Reproductive and developmental toxicity. i. In the rat
reproduction study, parental toxicity occurred as decreased body weight
at 5.0 mg/kg/day with a NOAEL of 3.0 mg/kg/day. There were no
developmental (pup) or reproductive effects up to 5.0 mg/kg/day
(highest dose tested).
ii. Post-natal sensitivity. Based on the absence of pup toxicity up
to dose levels which produced toxicity in the parental animals, there
is no evidence of special post-natal sensitivity to infants and
children in the rat reproduction study.
4. Subchronic toxicity. Short- and intermediate-term toxicity. The
maternal NOAEL of 1.0 mg/kg/day from the oral developmental toxicity
study in rats is also used for short- and intermediate-term Margins of
Exposure (MOE) calculations (as well as acute, discussed in (1) above).
The maternal LEL of this study of 2.0 mg/kg/day was based on tremors
from day 7-17 of dosing.
5. Chronic toxicity. i. The Referenced Dose (RfD) has been
established at 0.015 mg/kg/day. This RfD is based on a 1-year oral
feeding study in dogs with a NOAEL of 1.5 mg/kg/day, based on
intermittent tremors observed at the Lowest Observed Effects Level
(LOEL) of 3.0 mg/kg/day; an uncertainty factor of 100 is used.
ii. Bifenthrin is classified as a Group C chemical (possible human
carcinogen) based upon urinary bladder tumors in mice; assignment of a
Q* has not been recommended.
6. Animal metabolism. The metabolism of bifenthrin in animals is
adequately understood. Metabolism studies in rats with single doses
demonstrated that about 90% of the parent compound and its hydroxylated
metabolites are excreted.
7. Metabolite toxicology. The Agency has previously determined that
the metabolites of bifenthrin are not of toxicological concern and need
not be included in the tolerance expression.
8. Endocrine disruption. No special studies investigating potential
estrogenic or other endocrine effects of bifenthrin have been
conducted. However, no evidence of such effects were reported in the
standard battery of required toxicology studies which have been
completed and found acceptable. Based on these studies, there is no
evidence to suggest that bifenthrin has an adverse effect on the
C. Aggregate Exposure
1. Dietary exposure. -- Food. Tolerances have been established for
the residues of bifenthrin, in or on a variety of raw agricultural
commodities. Tolerances, in support of registrations, currently exist
for residues of bifenthrin on hops; strawberries; corn (field, seed,
and pop) grain, forage, and fodder; cottonseed; and from the associated
meat, milk and meat by-products from livestock commodities of cattle,
goats, hogs, horses, sheep, and poultry. Additionally, time-limited
tolerances associated with emergency exemptions were established for
broccoli, cauliflower, raspberries, cucurbits and canola. A pending
tolerance for artichokes also exists. For the purposes of assessing the
potential dietary exposure for these existing and pending tolerances as
well as the existing time-limited tolerances under FIFRA section 18
emergency exemptions, FMC has utilized available information on
anticipated residues, monitoring data and percent crop treated as
i. Acute exposure and risk. Acute dietary exposure risk assessments
are performed for a food-use pesticide if a toxicological study has
indicated the possibility of an effect of concern occurring as a result
of a 1 day or single exposure. For the purposes of assessing acute
dietary risk for bifenthrin, the maternal NOAEL of 1.0 mg/kg/day from
the oral developmental toxicity study in rats was used. The maternal
LEL of this study of 2.0 mg/kg/day was based on tremors from day 7-17
of dosing. This acute dietary endpoint was used to determine acute
dietary risks to all population subgroups. Available information on
anticipated residues, monitoring data and percent crop treated was
incorporated into a Tier 3 analysis, using Monte Carlo modeling for
commodities that may be consumed in a single serving. These assessments
show that the MOE are significantly greater than the EPA standard of
100 for all subpopulations. The 95th percentile of exposure for the
overall U. S. population was estimated to be 0.001105 mg/kg/day (MOE of
905); 99th percentile 0.002064 mg/kg/day (MOE of 484); and 99.9th
percentile 0.003955 mg/kg/day (MOE of 253). The 95th percentile of
exposure for all infants < 1 year old was estimated to be 0.002234 mg/
kg/day (MOE of 448); 99th percentile 0.004459 mg/kg/day (MOE of 224);
and 99.9th percentile 0.006945 mg/kg/day (MOE of 144). The 95th
percentile of exposure for nursing infants < 1 year old was estimated
to be 0.00061 mg/kg/day (MOE of 1,639); 99th percentile 0.001376 mg/kg/
day (MOE of 727); and 99.9th percentile 0.002009 mg/kg/day (MOE of
498). The 95th percentile of exposure for non-nursing infants < one
year old was estimated to be 0.002804 mg/kg/day (MOE of 357); 99th
percentile 0.004831 mg/kg/day (MOE of 207); and 99.9th percentile
0.007236 mg/kg/day (MOE of 138). The 95th percentile of exposure for
children 1 to 6 years old (the most highly exposed population subgroup)
was estimated to be 0.002377 mg/kg/day (MOE of 421); 99th percentile
0.003483 mg/kg/day (MOE of 287); and 99.9th percentile 0.00628 mg/kg/
day (MOE of 159). Therefore, FMC concludes that the acute dietary risk
of bifenthrin, as estimated by the dietary risk assessment, does not
appear to be of concern.
ii. Chronic exposure and risk. The acceptable RfD is based on a
NOAEL of 1.5 mg/kg/day from the chronic dog study and an uncertainty
factor of 100 is 0.015 mg/kg/day. The endpoint effect of concern were
tremors in both sexes of dogs at the LEL of 3.0 mg/kg/day. A chronic
dietary exposure/risk assessment has been performed for bifenthrin
using the above RfD. Available information on anticipated residues,
monitoring data and percent crop treated was incorporated into the
analysis to estimate the anticipated residue contribution (ARC). The
ARC is generally considered a more realistic estimate than an estimate
based on tolerance level residues. The ARC are estimated to be 0.000384
mg/kg body weight (bwt)/day and utilize 2.6% of the RfD for the overall
U. S. population. The ARC for non-nursing infants (<1 year) and
children 1-6 years old (subgroups most highly exposed) are estimated to
be 0.000837 mg/kg bwt/day and 0.001265 mg/kg bwt/day and utilizes 5.6%
and 8.4% of the RfD, respectively. Generally speaking, the EPA has no
cause for concern if the total dietary exposure from residues for uses
for which there are published and proposed tolerances is less than 100%
of the RfD. Therefore, FMC concludes that the chronic dietary risk of
bifenthrin, as estimated by the dietary risk assessment, does not
appear to be of concern.
2. Drinking water. Laboratory and field data have demonstrated that
bifenthrin is immobile in soil and will not leach into groundwater.
Other data show that bifenthrin is virtually insoluble in water and
extremely lipophilic. As a result, FMC concludes that residues reaching
surface waters from field runoff will quickly adsorb to sediment
particles and be partitioned
from the water column. Further, a screening evaluation of leaching
potential of a typical pyrethroid was conducted using EPA's Pesticide
Root Zone Model (PRZM3). Based on this screening assessment, the
potential concentrations of a pyrethroid in groundwater at depths of 1
and 2 meters are essentially zero (<0.001 parts per billion (ppb)).
Surface water concentrations for pyrethroids were estimated using PRZM3
and Exposure Analysis Modeling System (EXAMS) using standard EPA cotton
runoff and Mississippi pond scenarios. The maximum concentration
predicted in the simulated pond was 0.052 ppb. Concentrations in actual
drinking water would be much lower than the levels predicted in the
hypothetical, small, stagnant farm pond model since drinking water
derived from surface water would normally be treated before
consumption. Based on these analyses, the contribution of water to the
dietary risk estimate is negligible. Therefore, FMC concludes that
together these data indicate that residues are not expected to occur in
3. Non-dietary exposure. Analyses were conducted which included an
evaluation of potential non-dietary (residential) applicator, post-
application and chronic dietary aggregate exposures associated with
bifenthrin products used for residential flea infestation control and
agricultural/commercial applications. The aggregate analysis
conservatively assumes that a person is concurrently exposed to the
same active ingredient via the use of consumer or professional flea
infestation control products and to chronic level residues in the diet.
In the case of potential non-dietary health risks, conservative
point estimates of non-dietary exposures, expressed as total systemic
absorbed dose (summed across inhalation and incidental ingestion
routes) for each relevant product use category (i.e., lawn care) and
receptor subpopulation (i.e., adults, children 1 - 6 years and infants
< 1 year) are compared to the systemic absorbed dose NOAEL for
bifenthrin to provide estimates of the MOEs. Based on the toxicity
endpoints selected by EPA for bifenthrin, inhalation and incidental
oral ingestion absorbed doses were combined and compared to the
relevant systemic NOAEL for estimating MOEs.
In the case of potential aggregate health risks, the above
mentioned conservative point estimates of inhalation and incidental
ingestion non-dietary exposure (expressed as systemic absorbed dose)
are combined with estimates (arithmetic mean values) of chronic average
dietary (oral) absorbed doses. These aggregate absorbed dose estimates
are also provided for adults, children 1 - 6 years and infants < 1
year. The combined or aggregated absorbed dose estimates (summed across
non-dietary and chronic dietary) are then compared with the systemic
absorbed dose NOAEL to provide estimates of aggregate MOEs.
The non-dietary and aggregate (non-dietary + chronic dietary) MOEs
for bifenthrin indicate a substantial degree of safety. The total non-
dietary (inhalation + incidental ingestion) MOEs for post-application
exposure for the lawn care product evaluated was estimated to be
>51,000 for adults, 1,900 for children 1-6 years old and 1,800 for
infants < 1 year. The aggregate MOE (inhalation + incidental oral +
chronic dietary, summed across all product use categories) was
estimated to be 2,479 for adults, 559 for children 1-6 years old and
712 for infants (<1 year). It can be concluded that the potential non-
dietary and aggregate (non-dietary + chronic dietary) exposures for
bifenthrin are associated with substantial margins of safety.
D. Cumulative Effects
In consideration of potential cumulative effects of bifenthrin and
other substances that may have a common mechanism of toxicity, to our
knowledge there are currently no available data or other reliable
information indicating that any toxic effects produced by bifenthrin
would be cumulative with those of other chemical compounds; thus only
the potential risks of bifenthrin have been considered in this
assessment of its aggregate exposure. FMC intends to submit information
for the EPA to consider concerning potential cumulative effects of
bifenthrin consistent with the schedule established by EPA published in
the Federal Register of August 4, 1997 (62 FR 42020) (FRL 5734-6) and
other EPA publications pursuant to the Food Quality Protection Act
E. Safety Determination
1. U.S. population. Based on a complete and reliable toxicology
database, the acceptable RfD is 0.015 mg/kg/day, based on a NOAEL of
1.5 mg/kg/day from the chronic dog study and an uncertainty factor of
100. Available information on anticipated residues, monitoring data and
percent crop treated was incorporated into an analysis to estimate the
Anticipated Residue Contribution (ARC) for 26 population subgroups. The
ARC is generally considered a more realistic estimate than an estimate
based on tolerance level residues. The ARC are estimated to be 0.000384
mg/kg bwt/day and utilize 2.6% of the RfD for the overall U. S.
population. The ARC for non-nursing infants (<1 year) and children 1-6
years old (subgroups most highly exposed) are estimated to be 0.000837
mg/kg bwt/day and 0.001265 mg/kg bwt/day and utilizes 5.6% and 8.4% of
the RfD, respectively. Generally speaking, the EPA has no cause for
concern if the total dietary exposure from residues for uses for which
there are published and proposed tolerances is less than 100% of the
RfD. Therefore, FMC concludes that the chronic dietary risk of
bifenthrin, as estimated by the aggregate risk assessment, does not
appear to be of concern.
For the overall U.S. population, the calculated MOE at the 95th
percentile was estimated to be 905; 484 at the 99th percentile; and 253
at the 99.9th percentile. For all infants < one year old, the
calculated MOE at the 95th percentile was estimated to be 448; 224 at
the 99th percentile; and 144 at the 99.9th percentile. For nursing
infants < 1 year old, the calculated MOE at the 95th percentile was
estimated to be 1,639; 727 at the 99th percentile; and 498 at the
99.9th percentile. For non-nursing infants < 1 year old, the calculated
MOE at the 95th percentile was estimated to be 357; 207 at the 99th
percentile; and 138 at the 99.9th percentile. For the most highly
exposed population subgroup, children 1 - 6 years old, the calculated
MOE at the 95th percentile was estimated to be 421; 287 at the 99th
percentile; and 159 at the 99.9th percentile. Therefore, FMC concludes
that there is reasonable certainty that no harm will result from acute
exposure to bifenthrin.
2. Infants and children. --i. General. In assessing the potential
for additional sensitivity of infants and children to residues of
bifenthrin, FMC considered data from developmental toxicity studies in
the rat and rabbit, and a 2-generation reproductive 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. FFDCA section 408 provides that EPA may apply an
additional 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.
ii. Developmental toxicity studies. In the rabbit developmental
study, there were no developmental effects observed in the fetuses
exposed to bifenthrin. The maternal NOAEL was 2.67 mg/kg/day based on
head and forelimb twitching at the LOEL of 4 mg/kg/day. In the rat
developmental study, the maternal NOAEL was 1 mg/kg/day, based on
tremors at the LOEL of 2 mg/kg/day. The developmental (pup) NOAEL was
also 1 mg/kg/day, based upon increased incidence of hydroureter at the
LOEL 2 mg/kg/day. There were 5/23 (22%) litters affected (5/141 fetuses
since each litter only had one affected fetus) in the 2 mg/kg/day
group, compared with zero in the control, 1, and 0.5 mg/kg/day groups.
According to recent historical data (1992-1994) for this strain of rat,
incidence of distended ureter averaged 11% with a maximum incidence of
iii. Reproductive toxicity study. In the rat reproduction study,
parental toxicity occurred as decreased body weight at 5.0 mg/kg/day
with a NOAEL of 3.0 mg/kg/day. There were no developmental (pup) or
reproductive effects up to 5.0 mg/kg/day (highest dose tested).
iv. Pre- and post-natal sensitivity. --a. Pre-natal. Since there
was not a dose-related finding of hydroureter in the rat developmental
study and in the presence of similar incidences in the recent
historical control data, the marginal finding of hydroureter in rat
fetuses at 2 mg/kg/day (in the presence of maternal toxicity) is not
considered a significant developmental finding. Nor does it provide
sufficient evidence of a special dietary risk (either acute or chronic)
for infants and children which would require an additional safety
b. Post-natal. Based on the absence of pup toxicity up to dose
levels which produced toxicity in the parental animals, there is no
evidence of special post-natal sensitivity to infants and children in
the rat reproduction study.
v. Conclusion. Based on the above, FMC concludes that reliable data
support use of the standard 100-fold uncertainty factor, and that an
additional uncertainty factor is not needed to protect the safety of
infants and children. As stated above, aggregate exposure assessments
utilized significantly less than 1% of the RfD for either the entire U.
S. population or any of the 26 population subgroups including infants
and children. Therefore, it may be concluded that there is reasonable
certainty that no harm will result to infants and children from
aggregate exposure to bifenthrin residues.
F. International Tolerances
There are no Codex, Canadian, or Mexican residue limits for
residues of bifenthrin in or on corn, sweet. (Mark Dow)
[FR Doc. 98-26783 Filed 10-6-98; 8:45 am]
BILLING CODE 6560-50-F