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cyfluthrin (Baythroid) Pesticide Tolerance Petition Filing 3/97

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ENVIRONMENTAL PROTECTION AGENCY
[PF-717; FRL-5590-2]

Bayer Corporation; Pesticide Tolerance Petition Filing 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Notice of filing.
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SUMMARY: This notice announces the filing of a pesticide petition proposing 
regulations establishing tolerances for residues of the pyrethroid cyfluthrin 
in or on the raw agricultural commodities (RACs) group citrus, fruits and to 
establish a maximum residue limit for cyfluthrin on citrus oil and dried pulp. 
This notice includes a summary of the petition that was prepared by Bayer 
Corporation. 

DATES: Comments, identified by the docket control number [PF-717], must be 
received on or before April 14, 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 be 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 in ASCII file format. All comments and data in electronic 
form must be identified by docket control number [PF-717]. Electronic comments 
on this notice may be filed online at many Federal Depository Libraries. 
Additional information on electronic submissions can be found below this 
document. 

Information submitted as a comments concerning this document 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: George T. LaRocca, Product Manager 
(PM) 13, 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: Rm. 200, CM #2, 1921 Jefferson 
Davis Highway, Arlington, VA 22202. (703) 305-6100; 
larocca.george@epamail.epa.gov. 

SUPPLEMENTARY INFORMATION: EPA has received pesticide petitions (PP) 4F4313 
and 4H5687 from Bayer Corporation, 8400 Hawthorn Road, Kansas City, MO 64120. 
The petition proposes, pursuant to section 408(d) of the Federal Food Drug and 
Cosmetic Act, 21 U.S.C. section 346a, to amend 40 CFR 180.436 to establish 
tolerances for residues of the insecticide cyfluthrin, [cyano[4-fluoro-3-
phenoxyphenyl]-methyl-3-[2,2- dicloroethenyl]-2,2-
dimethylcyclopropanecarboxylate] in or on the raw agricultural commodities 
group citrus, fruits at 0.2 part per million (ppm) and the processed 
commodities citrus, oil and citrus, dried pulp at 0.3 part per million (ppm). 
The proposed analytical method is gas chromatography equipped with electron 
capture detector. 

As required by section 408(d) of the FFDCA, as recently amended by the Food 
Quality Protection Act, Bayer Corporation included in 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

A. Residue Chemistry

1. Use pattern. Baythroid 2 will be used on citrus only in California and 
Arizona, to control citrus thrips. A dosage of 6.4 fluid ounces of Baythroid 2 
(0.1 lb active ingredient per acre) will be applied by ground equipment only, 
in sufficient water for complete coverage of foliage in dilute or concentrate 
sprays, but not less than 25 gallons per acre. A single application may be 
made per season. 

2. Plant metabolism. The metabolism of cyfluthrin in plants is adequately 
understood. Studies have been conducted to delineate the metabolism of 
radiolabeled cyfluthrin in various crops all showing similar results. The 
residue of concern is cyfluthrin. 

3. Analytical methodology. Adequate analytical methodology (Gas liquid 
chromatography with an electron capture detector) is available for enforcement 
purposes.

The established tolerances for residues of cyfluthrin in/on eggs, milks, fat, 
meat and meat by-products of cattle, goats, hogs, horses, sheep and poultry 
are adequate to cover secondary residues resulting from the proposed use as 
delineated in 40 CFR 180.6(a)(2). 

4. Magnitude of the residue. On December 20, 1993, Bayer Corp. filed a 
petition (PP 4F4313) for a tolerance for residues of cyfluthrin on the raw 
agricultural commodity, citrus and proposed food/feed additive regulation 
(4H5687) for citrus oil, citrus dried pulp, and citrus molasses under section 
409 of FFDCA. A request was filed May 2, 1996, to withdraw the feed additive 
petition for citrus molasses, submitted in response to EPA's determination 
that citrus molasses is no longer considered a significant feed item. See 
EPA's final 860 Series Residue Chemistry Guidelines (860.1000) published as 
public drafts on August 25, 1995 (60 FR 44343) (formerly Table II of 
Subdivision O, Residue Chemistry, of the Pesticide Assessment Guidelines). 

The food/feed additive petition for citrus oil and citrus dried pulp has been 
revised to propose these tolerances at 0.3 ppm under section 408 instead 
section 409 in accordance the Food Quality Protection Act.

The proposed section 408 tolerance for cyfluthrin on citrus is 0.2 ppm. The 
highest average residue found in crop field trials for cyfluthrin on citrus 
fruits was 0.06 ppm. A processing study showed that in producing citrus oil 
and dried pulp residues concentrated 530 (a concentration factor of 5.3 x ). 
Thus with this information it is likely that cyfluthrin residues of 0.32 ppm 
(0.06 x 5.3) could occur in citrus oil and dried pulp.

B. Toxicological Profile

The data base for cyfluthrin is essentially complete. Data lacking but 
desirable are an acute neurotoxicity study in rats and a 90-day neurotoxicity 
study in rats. Although these data are lacking, Bayer Corp. believes there is 
sufficient toxicity data to support the proposed tolerance and these missing 
data will not significantly change the risk assessment. In a letter dated 
November 2, 1995, Bayer Corp. has committed to submit the acute neurotoxicity 
study by December 1996 and the 90-day neurotoxicity study by May 1997. 

The toxicology data cited in support of the tolerance include: 1. Chronic 
effects. A 12-month chronic feeding study in dogs with a no-observed effect 
level (NOEL) of 4 mg/kg/day. The lowest effect level (LEL) for this study is 
established at 16 mg/kg/day, based on slight ataxia, increased vomiting, 
diarrhea and decreased body weight. 

A 24-month chronic feeding/carcinogenicity study in rats with a NOEL of 2.5 
mg/kg/day and LEL of 6.2 mg/kg/day, based on decreased body weights in males, 
decreased food consumption in males, and inflammatory foci in the kidneys in 
females.

2. Acute toxicity. For the purposes of assessing acute dietary risk, the 
Agency has used an oral developmental toxicity study in rabbits with a 
maternal NOEL of 20 mg/kg/day and a maternal LEL of 60 mg/kg/day, based on 
decreased body weight gain and decreased food consumption during the dosing 
period. A fetal NOEL of 20 mg/kg/day and a fetal LEL of 60 mg/kg/day were also 
observed in this study. The LEL was based on increased resorptions and 
increased postimplantation loss. 

3. Carcinogenicity. A 24-month carcinogenicity study in mice was conducted. 
There were no carcinogenic effects observed under the conditions of the study.

A 24-month chronic feeding/carcinogenicity study in rats was conducted. There 
were no carcinogenic effects observed under the conditions of the study.

Mutagenicity tests were conducted, including several gene mutation assays 
(reverse mutation and recombination assays in bacteria and a Chinese hamster 
ovary(CHO)/HGPRT assay); a structural chromosome aberration assay (CHO/sister 
chromatid exchange assay); and an unscheduled DNA synthesis assay in rat 
hepatocytes. All tests were negative for genotoxicity.

4. Other. A metabolism study in rats showed that cyfluthrin is rapidly 
absorbed and excreted, mostly as conjugated metabolites in the urine, within 
48 hours. An enterohepatic circulation was observed. 

C. Aggregate Exposure

A chronic dietary exposure/risk assessment was performed for cyfluthrin using 
a Reference Dose (RfD) of 0.025 mg/kg bwt/day, based on a NOEL of 50 ppm (2.5 
mg/kg bwt/day) and an uncertainty factor of 100. The NOEL was determined in a 
2-year rat feeding study. The endpoint effects of concern were decreased body 
weights in males and inflammation of the kidneys in females at the LEL of 6.2 
mg/kg/day. For purposes of this dietary exposure/risk assessment tolerance 
level residues were used and percent crop treated assumption made for some of 
the commodities. The current estimated dietary exposure for the overall U.S. 
population resulting from established tolerances 0.009420 mg/kg/ bwt/day or 
37.6 percent of the RfD. The current estimated dietary exposure for the 
subgroup population exposed to the highest risk, non- nursing infants less 
than 1 year old, 0.025266 mg/kg bwt/day or 101 percent of the RfD. Although 
the estimate of dietary exposure for the subgroup, non-nursing infants less 
than 1 year old, is slightly higher than the Agency's level of concern, i.e., 
greater than 100 percent of the RfD, Bayer Corp. believes that actual exposure 
and risk would be lower. The basis for this is that the risk reflects a higher 
than actual dietary exposure because it assumes that 100 percent of most 
commodities for which cyfluthrin tolerances exist have cyfluthrin residues and 
that all will bear residue levels as high as the tolerances. In reality, all 
these commodities will not have residues of this pesticide and actual levels 
will be lower than tolerance levels. To assess the dietary exposure from the 
establishment of the proposed citrus tolerances, the incremental increase in 
dietary exposure was taken from the dietary exposure analysis conducted by the 
Agency. These estimates are based on the assumption that 100 percent of the 
citrus crop in the U.S. would be treated with cyfluthrin. In reality, this use 
of cyfluthrin will be limited to California and Arizona only for the control 
of citrus thrips. For the prior six years, cyfluthrin has been utilized in the 
California's Central Valley under the provisions of a FIFRA section 18 
Emergency Exemption. In 1995, approximately 77,000 out of 170,000 acres (46 
percent) of the citrus grown in Central Valley was treated with cyfluthrin. 
Assuming that a similar proportion of acreage, that is 46 percent, would be 
treated throughout California and Arizona, the total estimated acreage treated 
with cyfluthrin would be 94,000 acres. This represents only 9.4 percent of the 
1,026,000 fruit bearing acres of citrus grown in the U.S. Therefore, a 10 
percent treated crop adjustment to the dietary exposure can be considered 
appropriate. 

Adding this incremental exposure to the current estimated dietary exposure 
results in a total dietary exposure for the U.S. population of 0.0094934 mg/kg 
bwt/day representing 38 percent of RfD. The highest exposure group, non-
nursing infants will increase only very slightly, to 0.253653 mg/kg bwt/day 
representing 101.4 percent of the RfD. As described above, although this still 
slightly exceeds the RfD, actual exposure is expected to be much less.

Generally speaking, 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 the RfD. Therefore Bayer concludes that the chronic dietary risk 
of cyfluthrin, as estimated by the dietary risk assessment, does not appear to 
be of concern. 

Other potential sources of exposure to residues of pesticides are residues in 
drinking water and exposure from non-occupational sources. Based on available 
studies used in previous EPA assessments, Bayer Corp. does not anticipate 
exposures to cyfluthrin in drinking water. Non-occupational exposure to 
cyfluthrin may occur as a result of inhalation or contact from indoor 
residential, indoor commercial, and outdoor residential uses. The Agency does 
not currently have reliable data to determine aggregate exposures from these 
sources. However, determinations of worst case exposure from inhalation in 
indoor settings (continuous exposure at saturation vapor concentration) should 
indicate that adequate margins of safety exist even under these conditions. 
Since this evaluation greatly overestimates exposure, the contribution to 
aggregate exposure from inhalation in normal uses would be expected to be 
negligible. Estimations of outdoor residential exposure have been required for 
cyfluthrin in a data call-in issued in 1995. These data are being generated by 
the Outdoor Residential Exposure Task Force (ORETF). However, available data 
show that the acute dermal toxicity of cyfluthrin is very low, with the LD50 
being greater than 5,000 mg/kg, the highest dose tested. Sub-acute (21- day) 
dermal toxicity data showed only localized (skin) effects at higher level 
exposures (1,000 mg/kg/day and 340 mg/kg/day). Other than skin effects at 
these high exposure levels, no effects were observed at any exposure levels, 
the highest level tested being 1,000 mg/kg/day. The use rate for cyfluthrin on 
residential turf is 1 g (1,000 mg) active ingredient per 1000 square feet 
which would indicate that potential exposures would be well below levels 
tested. In addition, the localized skin effects seen at the prolonged higher 
exposures in animal tests have not been reported for non-occupational 
exposures to cyfluthrin in currently accepted uses, indicating that exposures 
are below the threshold of any observable effects. Indoor uses are limited to 
areas with little or no contact, so exposures would be expected to be even 
less. Thus, the dermal route of exposure does not appear to be significant and 
the contribution to aggregate exposure from dermal contact would be expected 
to be negligible.

In consideration of potential cumulative effects of cyfluthrin and other 
substances that have a common mechanism of toxicity, there are currently no 
available data or other reliable information indicating that any toxic effects 
produced by cyfluthrin would be cumulative with those of other chemical 
compounds; thus only the potential risks of cyfluthrin have been considered in 
this assessment of its aggregate exposure.

D. 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 it can be concluded that total aggregate exposure to cyfluthrin from all 
current uses as well as the proposed tolerance and maximum residue levels for 
the use of cyfluthrin on citrus will utilize little more than 38 percent of 
the RfD for the U.S. population. EPA generally has no concerns for exposures 
below 100 percent 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, it can be concluded that there is a reasonable 
certainty that no harm will result from aggregate exposure to cyfluthrin 
residues.

2. Infants and children. In assessing the potential for additional sensitivity 
of infants and children to residues of cyfluthrin, the data from developmental 
studies in both rat and rabbit and a 2-generation reproduction study in the 
rat can be considered. The developmental toxicity studies evaluate any 
potential adverse effects on the developing animal resulting from pesticide 
exposure of the mother during prenatal development . The reproduction study 
evaluates any effects from exposure to the pesticide on the reproductive 
capability of mating animals through two generations, as well as any observed 
systemic toxicity.

The toxicology data cited in support of the tolerance include: An oral 
developmental toxicity study in rats with a maternal and fetal NOEL of 10 
mg/kg/day (highest dose tested). An oral developmental toxicity study in 
rabbits with a maternal NOEL of 20 mg/kg/day and a maternal LEL of 60 
mg/kg/day, based on decreased body weight gain and decreased food consumption 
during the dosing period. A fetal NOEL of 20 mg/kg/day and a fetal LEL of 60 
mg/kg/day were also observed in this study. The LEL was based on increased 
resorptions and increased postimplantation loss.

A developmental toxicity study in rats by the inhalation route of 
administration with a maternal NOEL of 0.0011 mg/l and a LEL of 0.0047 mg/l, 
based on reduced mobility, dyspnea, piloerection, ungroomed coats and eye 
irritation. The fetal NOEL is 0.00059 mg/l and the fetal LEL is 0.0011 mg/l, 
based on sternal anomalies and increased incidence of runts. A second 
developmental toxicity study in rats by the inhalation route of administration 
has been submitted to the Agency and is currently under review.

A three-generation reproduction study in rats with a systemic NOEL of 2.5 
mg/kg/day and a systemic LEL of 7.5 mg/kg/day due to decreased parent and pup 
body weights. The reproductive NOEL and LEL are 7.5 mg/ kg/day and 22.5 
mg/kg/day respectively.

The Agency used the rabbit developmental toxicity study with a maternal NOEL 
of 20 mg/kg/day to assess acute dietary exposure and determine a margin of 
exposure (MOE) for the overall U.S. population and certain subgroups. Since 
this toxicological endpoint pertains to developmental toxicity the population 
group of concern for this analysis was women aged 13 and above, the subgroup 
which most closely approximates women of child-bearing age. The MOE is 
calculated as the ration of the NOEL to the exposure. For this analysis the 
Agency calculated the MOE to be over 600. Generally, MOE's greater than 100 
for data derived from animal studies are regarded as showing no appreciable 
risk.

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 
cyfluthrin relative to pre- and post-natal effects is complete. The no-effect-
levels observed in the developmental and reproduction study are equivalent or 
higher than the NOEL from the 2-year rat feeding study, used with a 100 fold 
uncertainty factor to establish the reference dose.

Therefore, an additional uncertainty factor is not warranted and that the RfD 
at 0.025 mg/kg/day is appropriate for assessing aggregate risk to infants and 
children.

Using the conservative exposure assumptions described above, EPA has 
previously concluded that the residues from use of cyfluthrin on citrus will 
contribute the highest incremental increase to the aggregate exposure to the 
population subgroup children 1 to 6 years old, accounting for 3.9 percent of 
the RfD and giving a total dietary exposure from all uses of 95.9 percent of 
the RfD for this subgroup. However, this assessment was based on an assumption 
of 100 percent crop treated. When adjusted for a 10 percent crop treatment (as 
described in section B. above) the incremental exposure is negligible, 
increasing form the current 0.022985 mg/kg bwt /day (91.9 percent of the RfD) 
to 0.231522 mg /kg bwt/day or 92.6 percent of the RfD. For nursing infants 
current exposure is 0.005692 mg/kg bwt/day or 22.8 percent of the RfD. The use 
on citrus would increase exposure to 0.0057377 mg/kg bwt/day representing 22.9 
percent of the RfD. For children 7 to 12, current exposure is 0.015237 mg/kg 
bwt/ day, 60.9 percent of the RfD. The use on citrus would increase this to 
0.153416 mg/kg bwt /day, or 61.4 percent of the RfD. For non-nursing infants, 
the current is exposure is calculated to be 0.025267 mg/kg bwt /day, 101 
percent of the RfD. The use on citrus would increase this slightly to 
0.0253653 or 101.4 percent. Both the current and the resulting calculated 
exposure from adding the estimated exposure from citrus exposure are slightly 
higher than the Agency's level of concern. However, the Agency has previously 
assessed this risk in the evaluation of PP 2F4137 and believed the actual 
exposure and risk would be much lower. The basis for this was the fact that 
this calculated exposure assumes, with the exception of citrus, that 100 
percent of the commodities for which cyfluthrin tolerance exists have residues 
and that the residues all bear residues as high as the tolerance levels. In 
reality, it is known that not all commodities will have cyfluthrin residues 
and actual levels will be lower than the tolerance values. In addition, the 
food commodity that contributes most to this slight exceedence is milk, at 
88.2 percent of the RfD; 71.2 percent from milk fat and 17 percent from whole 
milk and milk sugars. However, metabolism data indicate that essentially all 
of the cyfluthrin will concentrate in milk fat and there would be negligible 
amounts in other components. Thus the 17 percent contribution from non-milk 
fat portions of milk is an overestimation of actual exposure, which would be 
below the RfD. 

Generally, EPA has no cause for concern if the total aggregate exposure is 
less than the RfD, therefore it may be concluded that there is a reasonable 
certainty of no harm will result to infants and children.

E. Conclusions

The available data indicate that there is reasonable certainty of no harm from 
the incremental exposure resulting from the potential residues of cyfluthrin 
from the use of Baythroid 2, EPA Reg. No. 3125- 351, on citrus. Thus in 
accordance with the provisions of the FFDCA as amended August 3, 1996, 
regulations to establish the tolerance and maximum residue levels to support 
this use can be effected. 

F. International Tolerances

There are no Codex maximum residue levels (MRLs) established for residues 
ofcyfluthrin on citrus fruits or any resulting processed products.

II. Public Record

Interested persons are invited to submit comments on this notice of filing. 
Comments must bear a notation indicating the docket control number, [PF-717]. 
All written comments filed in response to this petition will be available in 
the Public Response and Program Resources Branch, at the address given above 
from 8:30 a.m. to 4 p.m., Monday through Friday, except legal holidays.

A record has been established for this notice under docket control number [PF-
717] 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 Rm. 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 ASCII file avoiding the use of 
special characters and any form of encryption. 

The official record for this notice, 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 record which will also include 
all comments submitted directly in writing. The official record is the paper 
record maintained at the address in "ADDRESSES" at the beginning of this 
document. 

Authority: 21 U.S.C. 346a.

List of Subjects

Environmental Protection, Administrative practice and procedure, Agricultural 
commodities, Pesticides and pests, Reporting and recordkeeping requirements.

Dated: March 7, 1997.

Stephen L. Johnson,
Director, Registration Division, Office of Pesticide Programs. 

[FR Doc. 97-6516 Filed 3-13-97; 8:45 am]