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Bayer Corporation; Pesticide Tolerance Petition Filing
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: February 26, 1997 (Volume 62, Number 38)]
[Notices]
[Page 8731-8734]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26fe97-70]
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ENVIRONMENTAL PROTECTION AGENCY
[PF-713; FRL-5589-2]
Bayer Corporation; Pesticide Tolerance Petition Filing
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: This notice announces the filing of a pesticide petition
proposing the establishment of a regulation for residues of
imidacloprid in or on cereal grain, sweet corn, safflower and soybeans.
The notice contains a summary of the petition prepared by the
petitioner, Bayer Corporation.
DATES: Comments, identified by the docket number [PF-713], must be
received on or before March 28, 1997.
ADDRESSES: By mail, submit written comments to: Public Response and
Program Resources Branch, Field Operations Division (7506C), Office of
Pesticide Programs, Environmental Protection Agency, 401 M St., SW.,
Washington, DC 20460. In person, bring comments to: Rm. 1132 CM #2,
1921 Jefferson Davis Highway, Arlington, VA 22202. Comments and data
may also be submitted electronically by sending electronic mail (e-
mail) to: 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. Comments and data will also be accepted on
disks in WordPerfect 5.1 file format or ASCII file format. All comments
and data in electronic form must be identified by the docket number
[PF-713]. Electronic comments on this notice may be filed online at
many Federal Depository Libraries. Additional information on electronic
submissions can be found in Unit II of this document.
Information submitted as comments concerning this notice may be
claimed confidential by marking any part or all of that information as
``Confidential Business Information'' (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. 1132 at the
address given above, from 8:30 a.m. to 4 p.m., Monday through Friday,
excluding legal holidays.
FOR FURTHER INFORMATION CONTACT: By mail: Dennis H. Edwards, Jr.,
Product Manager (PM) 19, Registration Division (7505C), Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. Office
location, telephone number and e-mail address: Rm. 207, CM #2, 1921
Jefferson Davis Hwy., Arlington, VA 22202, (703)-305-6386; e-mail:
edwards.dennis@epamail.epa.gov.
SUPPLEMENTARY INFORMATION: EPA has received a pesticide petition (PP)
6F4765 pursuant to section 408(d) of the Federal Food, Drug and
Cosmetic Act, as amended, 21 U.S.C. 346a(d), by the Food Quality
Protection Act of 1996 (FQPA) (Pub. L. 104-170, 110 Stat. 1489) from
Bayer Corporation (``Bayer''), 8400 Hawthorn Rd., P.O. Box 4913, Kansas
City, MO 64120-0013 proposing to amend 40 CFR 180.472 by establishing
tolerances for inadvertent or indirect residues of the insecticide,
imidacloprid: 1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2-
imidazolidinimine and its metabolites containing the 6-chloro-pyridinyl
moiety in or on cereal grain [grain 0.05 parts per million (ppm),
forage (2.0 ppm), stover (0.3 ppm), hay (6.0 ppm), and straw (3.0
ppm)], sweet corn (0.05 ppm), legume vegetables (0.3 ppm) [and foliage
thereof (2.5 ppm)], and safflower seed (0.05 ppm). The nature of the
imidacloprid residue in plants and livestock is adequately understood.
The analytical method for determining residues is a common moiety
method for imidacloprid and its metabolites containing the 6-chloro-
pyridinyl moiety using oxidation, derivatization, and analysis by
capillary gas chromatography with a mass-selective detector. These
tolerances would allow for a 1-month plant back interval for these
crops following normal application of imidacloprid-containing products.
EPA has determined that the petition contains 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 granting of the petition. Additional data
may be needed before EPA rules on the petition.
As required by section 408(d) of the FFDCA, as recently amended by
the FQPA, Bayer Corporation included in
[[Page 8732]]
the petition a summary of the petition and authorization for the
summary to be published in the Federal Register in a notice of receipt
of the petition. The summary represents the views of Bayer Corporation;
EPA is in the process of evaluating the petition. As required by
section 408(d)(3) EPA is including the summary as a part of this notice
of filing. EPA may have made minor edits to the summary for the purpose
of clarity.
I. Petition Summary
Imidacloprid is a broad-spectrum insecticide with excellent
systemic and contact toxicity characteristics which is used primarily
for sucking insects.
A. Plant Metabolism and Analytical Method
The metabolism of imidacloprid in plants is adequately understood
for the purposes of these tolerances. The residues of concern are
combined residues of imidacloprid and its metabolites containing the 6-
chloro-pyridinyl moiety, all calculated as imidacloprid. The analytical
method is a common moiety method for imidacloprid and its metabolites
containing the 6-chloropyridinyl moiety using a permanganate oxidation,
silyl derivatization, and capillary GC-MS selective ion monitoring.
This method has successfully passed a petition method validation in EPA
labs. There is a confirmatory method specifically for imidacloprid and
several metabolites utilizing GC/MS and HPLC-UV which has been
validated by the EPA as well. Imidacloprid and its metabolites are
stable for at least 24 months in the commodities when frozen.
B. Magnitude of the Residue
Field rotational crop studies were conducted in three states where
soil was treated with imidacloprid at a rate of 0.3 lbs active
ingredient per acre (ai/A) (1x). After 30 days, rotational crops were
planted, grown to maturity, and harvested at appropriate times. Residue
levels in cereal grain, sweet corn (K+CWHR), and safflower seed were
<0.05 ppm. Maximum residues were 1.81 ppm in cereal grain forage, 0.26
ppm in cereal grain stover, 2.7 ppm in cereal grain straw, 0.22 ppm in
legume vegetables, and 2.33 ppm in legume vegetable foliage. These
residue data support tolerances of 0.05 ppm for cereal grain, sweet
corn (K+CWHR), and safflower seed; 2.0 ppm for cereal grain forage; 0.3
ppm for cereal grain stover; 6.0 ppm for cereal grain hay; 3.0 ppm in
cereal grain straw; 0.3 ppm in legume vegetables; and 2.5 ppm for the
foliage of legume vegetables. No processing studies were submitted with
this petition, however, available data would indicate that tolerances
on corn meal (0.05 ppm), soybean meal (0.5 ppm) and a time-limited
tolerance on safflower meal (0.5 ppm) could be considered. The
registrant has committed to provide data to support these processed
commodities. CBTS has concluded that existing poultry meat and egg
tolerances are adequate to support the proposed new uses of
imidacloprid.
C. Toxicological Profile of Imidacloprid
1. Acute toxicity. The acute oral LD50 values for imidacloprid
technical ranged from 424 to 475 milligrams per kilogram of body weight
(mg/kg bwt) in the rat. The acute dermal LD50 was greater than
5,000 milligrams per kilogram (mg/kg) in rats. The 4-hour rat
inhalation LC50 was >69 milligrams per cubic meter (mg/m3)
air (aerosol). Imidacloprid was not irritating to rabbit skin or eyes.
Imidacloprid did not cause skin sensitization in guinea pigs.
2. Genotoxicity. Extensive mutagenicity studies conducted to
investigate point and gene mutations, DNA damage and chromosomal
aberration, both using in vitro and in vivo test systems show
imidacloprid to be non-genotoxic.
3. Reproductive and developmental toxicity. A two-generation rat
reproduction study gave a no-observed-effect level (NOEL) of 100 ppm (8
mg/kg/bwt). Rat and rabbit developmental toxicity studies were negative
at doses up to 30 mg/kg/bwt and 24 mg/kg/bwt, respectively.
4. Subchronic toxicity. Ninety-day (90-day) feeding studies were
conducted in rats and dogs. The NOEL's for these tests were 14 mg/kg
bwt/day (150 ppm) and 5 mg/kg bwt/day (200 ppm) for the rat and dog
studies respectively.
5. Chronic toxicity/oncogenicity. A 2-year rat feeding/
carcinogenicity study was negative for carcinogenic effects under the
conditions of the study and had a NOEL of 100 ppm (5.7 mg/kg/bwt in
male and 7.6 mg/kg/bwt female) for noncarcinogenic effects that
included decreased body weight gain in females at 300 ppm and increased
thyroid lesions in males at 300 ppm and females at 900 ppm. A 1-year
dog feeding study indicated a NOEL of 1,250 ppm (41 mg/kg/bwt). A 2-
year mouse carcinogenicity study that was negative for carcinogenic
effects under conditions of the study and that had a NOEL of 1,000 ppm
(208 mg/kg/day).
Imidacloprid has been classified under ``Group E'' (no evidence of
carcinogenicity) by EPA's OPP/HED's Reference Dose (RfD) Committee.
There is no cancer risk associated with exposure to this chemical. The
reference dose (RfD) based on the 2-year rat feeding/carcinogenic study
with a NOEL of 5.7 mg/kg/bwt and 100-fold uncertainty factor, is
calculated to be 0.057 mg/kg/bwt. The theoretical maximum residue
contribution (TMRC) from published uses is 0.008358 mg/kg/bwt/day
utilizing 14.7% of the RfD.
6. Endocrine effects. The toxicology database for imidacloprid is
current and complete. Studies in this database include evaluation of
the potential effects on reproduction and development, and an
evaluation of the pathology of the endocrine organs following short- or
long-term exposure. These studies revealed no primary endocrine effects
due to imidacloprid.
7. Mode of action. Imidacloprid exhibits a mode of action different
from traditional organophosphate, carbamate, or pyrethroid
insecticides. Imidacloprid acts by binding to the nicotinergic receptor
sites at the postsynaptic membrane of the insect nerve. Due to this
novel mode of action, imidacloprid has not shown any cross resistance
to registered alternative insecticides and is a valuable tool for use
in IPM or resistance management programs.
D. Aggregate Exposure
Imidacloprid is a broad-spectrum insecticide with excellent
systemic and contact toxicity characteristics with both food and non-
food uses. Imidacloprid is currently registered for use on various food
crops, tobacco, turf, ornamentals, buildings for termite control, and
cats and dogs for flea control. Those potential exposures are addressed
below:
1. Dietary. The EPA has determined that the reference dose (RfD)
based on the 2-year rat feeding/carcinogenic study with a NOEL of 5.7
mg/kg/bwt and 100-fold uncertainty factor, is calculated to be 0.057
mg/kg/bwt. As published in the Federal Register of December 13, 1995
(60 FR 64006)(FRL-4990-5) and June 12, 1996 Federal Register (61 FR
2674)(FRL-5367-8) (petition to establish tolerances on leafy green
vegetables (PP 5F4522/R2237)), the TMRC from published uses is 0.008358
mg/kg/bwt/day utilizing 14.7% of the RfD for the general population.
For the most highly exposed subgroup in the population, non-nursing
infants (< 1 year old), the TMRC for the published tolerances is
0.01547 mg/kg/day. This is equal to 27.1% of the RfD. Therefore, Bayer
believes that dietary exposure from the existing uses including the
currently proposed inadvertent or indirect residue tolerances will not
exceed the RfD for
[[Page 8733]]
any subpopulation (including infants and children).
2. Water. Although the various imidacloprid labels contain a
statement that this chemical demonstrates the properties associated
with chemicals detected in groundwater, Bayer is not aware of
imidacloprid being detected in any wells, ponds, lakes, streams, etc.
from its use in the United States. In studies conducted in 1995,
imidacloprid was not detected in 17 wells on potato farms in Quebec,
Canada. In addition, groundwater monitoring studies are currently
underway in California and Michigan. Therefore, Bayer believes that
contributions to the dietary burden from residues of imidacloprid in
water would be inconsequential.
3. Non-occupational-- a. Residential turf. Bayer has conducted an
exposure study to address the potential exposures of adults and
children from contact with imidacloprid treated turf. The population
considered to have the greatest potential exposure from contact with
pesticide treated turf soon after pesticides are applied are young
children. Margins of safety (MOS) of 7,587 to 41,546 for 10-year-old
children and 6,859 to 45,249 for 5-year-old children were estimated by
comparing dermal exposure doses to the imidacloprid no observable
effect level of 1,000 mg/kg/day established in a 15-day dermal toxicity
study in rabbits. The estimated safe residue levels of imidacloprid on
treated turf for 10-year-old children ranged from 5.6 to 38.2 g/
cm2 and for 5-year-old children from 5.1 to 33.5 g/cm2. This
compares with the average imidacloprid transferable residue level of
0.080 g/cm2 present immediately after the sprays have dried. These
data indicate that children can safely contact imidacloprid-treated
turf as soon after application as the spray has dried.
b. Termiticide. Imidacloprid is registered as a termiticide. Due to
the nature of the treatment for termites, exposure would be limited to
that from inhalation and was evaluated by EPA's Occupational and
Residential Exposure Branch's (OREB) and Bayer. Data indicate that the
Margins of Safety for the worst case exposures for adults and infants
occupying a treated building who are exposed continuously (24 hours/
day) are 8.0 x 107 and 2.4 x 108, respectively--and
exposure can thus be considered negligible.
c. Tobacco smoke. Studies have been conducted to determine residues
in tobacco and the resulting smoke following treatment. Residues of
imidacloprid in cured tobacco following treatment were a maximum of 31
ppm (7 ppm in fresh leaves). When this tobacco was burned in a
pyrolysis study only 2 percent of the initial residue was recovered in
the resulting smoke (main stream plus side stream). This would result
in an inhalation exposure to imidacloprid from smoking of approximately
0.0005 mg per cigarette. Using the measured subacute rat inhalation
NOEL of 5.5 mg/m3, it is apparent that exposure to imidacloprid
from smoking (direct and/or indirect exposure) would not be
significant.
d. Pet treatment. Human exposure from the use of imidacloprid to
treat dogs and cats for fleas has been addressed by EPA's OREB who have
concluded that due to the fact that imidacloprid is not an inhalation
or dermal toxicant and that while dermal absorption data are not
available, imidacloprid is not considered to present a hazard via the
dermal route.
4. Cumulative effects. No other chemicals having the same mechanism
of toxicity are currently registered, therefore, Bayer believes that
there is no risk from cumulative effects from other substances with a
common mechanism of toxicity.
E. Safety Determinations
1. U.S. population in general. Using the conservative exposure
assumptions described above and based on the completeness and
reliability of the toxicity data, Bayer concludes that total aggregate
exposure to imidacloprid from all current uses including those
currently proposed will utilize little more than 15% of the RfD for the
U.S. population. EPA generally has no concerns for exposures below 100%
of the RfD, because the RfD represents the level at or below which
daily aggregate exposure over a lifetime will not pose appreciable
risks to human health. Thus, Bayer concludes that there is a reasonable
certainty that no harm will result from aggregate exposure to
imidacloprid residues.
2. Infants and children. In assessing the potential for additional
sensitivity of infants and children to residues of imidacloprid, the
data from developmental studies in both rat and rabbit and a two-
generation reproduction study in the rat have been considered. The
developmental toxicity studies evaluate potential adverse effects on
the developing animal resulting from pesticide exposure of the mother
during prenatal development . The reproduction study evaluates effects
from exposure to the pesticide on the reproductive capability of mating
animals through two generations, as well as any observed systemic toxicity.
FFDCA section 408 provides that EPA may apply an additional safety
factor for infants and children in the case of threshold effects to
account for pre- and post- natal effects and the completeness of the
toxicity database. Based on current toxicological data requirements,
the toxicology database for imidacloprid relative to pre- and post-
natal effects is complete. Further for imidacloprid, the NOEL of 5.7
mg/kg/bwt from the 2-year rat feeding/carcinogenic study, which was
used to calculate the RfD (discussed above), is already lower than the
NOELs from the developmental studies in rats and rabbits by a factor of
4.2 to 17.5 times. Since a 100-fold uncertainty factor is already used
to calculate the RfD, Bayer surmises that an additional uncertainty
factor is not warranted and that the RfD at 0.057 mg/kg/bwt/day is
appropriate for assessing aggregate risk to infants and children.
Using the conservative exposure assumptions described above, EPA
has concluded that the TMRC from use of imidacloprid from published
uses is 0.008358 mg/kg/bwt/day utilizing 14.7% of the RfD for the
general population. For the most highly exposed subgroup in the
population, non-nursing infants (< 1 year old), the TMRC for the
published tolerances is 0.01547 mg/kg/day. This is equal to 27.1% of
the RfD. Therefore, Bayer concludes that dietary exposure from the
existing uses including the currently proposed tolerances will not
exceed the RfD for any subpopulation (including infants and children).
F. Other Considerations
The nature of the imidacloprid residue in plants and livestock is
adequately understood. The residues of concern are combined residues of
imidacloprid and it metabolites containing the 6-chloropyridinyl
moiety, all calculated as imidacloprid. The analytical method is a
common moiety method for imidacloprid and its metabolites containing
the 6-chloropyridinyl moiety using a permanganate oxidation, silyl
derivatization, and capillary GC-MS selective ion monitoring. There is
an additional confirmatory method available. Imidacloprid and its
metabolites have been shown to be stable for at least 24 months in
frozen storage.
G. International Tolerances
No CODEX Maximum Residue Levels (MRL's) have been established for
residues of Imidacloprid on any crops at this time.
II. Public Record
EPA invites interested persons to submit comments on this notice of
[[Page 8734]]
filing. Comments must bear a notification indicating the docket control
number [PF-713].
A record has been established for this notice under docket numbers
[PF-713] (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 public
record is located in Room 1132 of the Public Response and Program
Resources Branch, Field Operations Division (7506C), Office of
Pesticide Programs, Environmental Protection Agency, Crystal Mall #2,
1921 Jefferson Davis Highway, Arlington, VA.
Electronic comments can 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 all comments 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.
List of Subjects
Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and record
keeping requirements.
Dated: February 10, 1997.
Stephen L. Johnson,
Director, Registration Division, Office of Pesticide Programs.
[FR Doc. 97-4627 Filed 2-25-97; 8:45 am]
BILLING CODE 6560-50-F