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pelargonic acid; Pesticide Tolerance Petition 1/97

CHEMICAL PROFILES/HERBICIDE & GROWTH REGULATOR/pelargonic acid 
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ENVIRONMENTAL PROTECTION AGENCY
[PF-685; FRL-5579-3]
Mycogen 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 a 
regulation establishing an exemption from the requirement of a tolerance for 
residues of the pesticide pelargonic acid on all raw agricultural commodities. 
This notice includes a summary of the petition that was prepared by the 
petitioner, Mycogen Corporation. 
DATES: Comments, identified by the docket control number [PF-685], must be 
received by EPA on or before February 24, 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, Crystal Mall #2, 1921 Jefferson 
Davis Hwy., Arlington, VA. 
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 docket number [PF-685]. No "Confidential Business 
Information" (CBI) should be submitted through e-mail. Electronic comments on 
this notice of filing 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 a comment concerning this document 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 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: Michael Mendelsohn, Biopesticides and 
Pollution Prevention Division (7501W), Office of Pesticide Programs, 
Environmental Protection Agency, 401 M St., SW., Washington, DC 20460. Office 
location, telephone number, and e-mail address: 5th Floor, CS #1, 2805 
Jefferson Davis Highway, Arlington, VA, 703-308-8715; e-mail: 
mendelsohn.michael@epamail.epa.gov.
SUPPLEMENTARY INFORMATION: EPA has received pesticide petition (PP) 6F4625 
from Mycogen Corporation, 4980 Carroll Canyon Road, San Diego, CA 92121. The 
petition proposes, pursuant to section 408 of the Federal Food, Drug, and 
Cosmetic Act (FFDCA), 21 U.S.C. 346a, to amend 40 CFR part 180 by establishing 
an exemption from the requirement of a tolerance for residues of pelargonic 
acid on all raw agricultural commodities. 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 support granting of the 
petition. Additional data may be needed before EPA rules on the petition. 
Mycogen has stated that an analytical method for the detection and measurement 
of pelargonic acid residues is not necessary to protect the public health and 
environment. They state that the natural occurrence of pelargonic acid in our 
food supply and environment, and the rapid metabolism and degradation of 
pelargonic acid to background levels in humans, plants and soil, eliminate the 
need to quantify pelargonic acid residues.
As required by section 408(d) of the FFDCA, as recently amended by the Food 
Quality Protection Act, Mycogen 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 Mycogen; EPA, as mentioned above, 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
This unit summarizes information cited by Mycogen to support the proposed 
tolerance.
A. Pelargonic Acid Uses
Pelargonic acid is currently used as the active ingredient in two unique 
pesticide products. First, it is used as a contact, non- selective, 
broadspectrum, foliar-applied herbicide. As the active ingredient in 
Scythe<Register> Herbicide (EPA Reg. No. 53219-7), registered by EPA for non-
crop uses on April 7, 1994, pelargonic acid will only control actively growing 
emerged green vegetation. Pelargonic acid provides burndown of both annual and 
perennial broadleaf and grass weeds, as well as most mosses and other 
cryptogams. The spray quickly penetrates plant tissue and disrupts normal cell 
membrane permeability and cellular physiology. The disruption of the cell 
membrane results in cell leakage and death of all contacted tissue. The 
product does not translocate, and it will burn only those plant parts that 
make contact with spray solution. Scythe provides no residual 
[[Page 3689]]
weed control; therefore, repeat treatments may be necessary for new plants 
emerging from seed or regrowth of treated vegetation. 
Scythe Herbicide contains as the active ingredient 57 percent pelargonic acid 
and 3 percent related fatty acids (C6 - C12). One gallon of Scythe contains 
4.2 pounds (lbs) of pelargonic acid. The application rate will range from 3 
percent to 10 percent v/v delivered at 75 to 200 gallons of spray solution per 
acre through boom, hand- held, or high volume equipment. Therefore, the rate 
of use of pelargonic acid will be 9.45 lbs to 84 lbs per acre. Combinations 
with selected products may further reduce the application rate to a low 0.78 
lbs to 2.1 lbs per acre (0.25 percent solution in 75 or 200 gallons spray per 
acre).
Second, pelargonic acid is used as a fruit blossom thinner that promotes 
return bloom (annual bearing) and increased fruit size and quality in apple 
and pear. Thinex<Register> Blossom Thinner (EPA Reg. No. 53219-11) was 
registered as a biochemical pesticide due to the natural occurrence of 
pelargonic acid, the low use rates and the unique non-toxic mode of action. 
Thinex works on contact by damaging the stigma or female flower part of the 
blossom, thus preventing pollination of a certain percentage of flowers. A 
blossom that has already been fertilized at the time of application will be 
undamaged by Thinex. No more than 2 applications per year are made. On 
February 14, 1996, pelargonic acid was exempt under 40 CFR 180.1159 from the 
requirement of a tolerance when used as a blossom thinning agent on apple and 
pear.
Thinex Blossom Thinner contains as the active ingredient 57 percent pelargonic 
acid and 3 percent related fatty acids (C6 - C12). The application rate as a 
blossom thinner ranges from 0.5 pints to 4 pints of product to make 100 
gallons of spray solution. One hundred to 400 gallons of spray solution per 
acre may be used. Therefore, the rate of use of pelargonic acid as a blossom 
thinning agent ranges from a low 0.26 lbs to a high 8.4 lbs per acre.
B. Product Identity/Chemistry
Pelargonic acid (C8H17COOH), a nine-carbon straight-chain fatty acid commonly 
referred to as nonanoic acid, is a naturally- occurring fatty acid found in 
the environment and in our food supply. 
Pelargonic acid has been found to occur naturally in low concentrations in 
soil. The degradation of pelargonic acid applied to soil occurs very rapidly 
by microbial means, not through hydrolysis or photolysis. Degradation occurs 
under aerobic conditions with beta- oxidation being the principal pathway of 
metabolism. 
Pelargonic acid has been shown to occur naturally in our food supply. For 
example, it has been identified in grapes, cheese and milk at levels from 10 
parts per million (ppm) to 400 ppm. Some literature references cite its 
natural occurrence in soybeans (trace levels), oranges (130 ppm), beans (trace 
levels), tobacco (0.27 ppm) and potatoes (1.18 ppm). In a cross-section of 
apple varieties analyzed by Mycogen, pelargonic acid was found at levels from 
20 parts per billion (ppb) to 320 ppb.
Fatty acids, including pelargonic acid, are metabolized in mammalian systems 
to produce energy. The oxidative degradation of fatty acids is a central 
metabolic pathway in humans, animals and plants. Fatty acids of varying chain 
lengths are metabolized into two-carbon fragments through a sequence of 
enzyme-catalyzed reactions. The metabolic products are then incorporated into 
fats, carbohydrates and amino acids.
The magnitude of pelargonic acid residues from applications of Scythe 
Herbicide anticipated at time of harvest will be insignificant beyond 
naturally-occurring levels and to normal dietary exposure. Applications of 
Scythe Herbicide will not directly contact desirable food commodities since 
exposure will be intentionally avoided by the grower because crop damage may 
result. Any residues of pelargonic acid on food commodities will only occur as 
a result of spray drift, thus minimizing residues of pelargonic acid on the 
food commodity. 
An analytical method for detecting and measuring the levels of pelargonic acid 
residue is not necessary to protect the public health and environment. The 
natural occurrence of pelargonic acid in our food supply and environment, and 
the rapid metabolism and degradation of pelargonic acid to background levels 
in humans, plants and soil, eliminate the need to quantify pelargonic acid 
residue from applications as a herbicide or a blossom thinner. 
C. Mammalian Toxicological Profile
Mycogen has submitted to EPA a comprehensive toxicology data package and 
referenced several published articles concluding that residues of pelargonic 
acid will be safe to human health. 
Although a significant concentration of pelargonic acid can be irritating to 
eyes and skin, toxicology data confirms that exposure to residues of 
pelargonic acid beyond naturally occurring background levels will be 
practically non-toxic to human health. The following mammalian toxicity 
studies have been conducted to support the tolerance exemption for residues of 
pelargonic acid: 
Acute Oral LD50: >5000 mg/kg
Acute Dermal LD50: >2000 mg/kg
Acute Inhalation LC50: >1.244 mg/L
Dermal Irritation (Rat): Severely Irritating Eye Irritation (Rabbit): Severely 
Irritating Skin Sensitization (Guinea Pig): Not sensitizing 
A range finding test to determine dosing concentrations for a 90- Day Rat Oral 
Toxicity study produced no adverse effects from pelargonic acid at any dose 
level for 3 weeks, including the highest dose of 20,000 ppm (2 percent), or 
1,834 mg/kg/day, for a period of 2 weeks. 
A developmental toxicity screen study in rats produced a NOEL of 1,500 
mg/kg/day (only dose tested). Pelargonic acid was tested at one dose 
administered by gavage in corn oil to 22 CD rats (20 pregnant) on days 6 
through 15 of gestation. No evidence of maternal or developmental toxicity was 
seen.
A chronic dermal toxicity study in mice resulted in no evidence of severe 
dermal or systemic toxicity. Fifty mice were treated twice- weekly with 50 mg 
doses of undiluted pelargonic acid for 80 weeks. Histopathology revealed no 
tumors of the skin or the internal organs. 
A gene mutation assay in mouse lymphoma cells (L5178Y TK <plus- minus>) 
concluded that pelargonic acid was negative for inducing mutations without 
metabolic activation, and was considered weakly positive for inducing 
mutations at the TK locus of culture mouse (L5178Y TK <plus-minus>) cells in 
the presence of S9-induced metabolic activation. Mutations were induced at 
levels greater than or equal to 50 mg/ml. However, this occurred in the 
presence of increasing moderate-to-severe cytotoxicity and small colony 
development and may reflect gross chromosomal changes or damage rather than 
actual mutational changes within the TK gene locus. 
In an in-vivo mouse micronucleus assay, groups of ICR mice (15/sex/ dose) were 
administered single oral doses of 1,250, 2,500, or 5,000 mg/ kg pelargonic 
acid. The bone marrow cells were harvested 24, 48, and 72 hours post-
treatment. No significant increases in the frequency of micronucleated 
polychromatic erythrocytes (PCEs) were observed in either sex at any dose; 
thus, pelargonic acid was negative in the micronucleus assay.
A reverse gene mutation assay (Ames Test) concluded that pelargonic acid was 
not mutagenic under the conditions of the study. 
D. Aggregate Exposure
Pelargonic acid is a naturally-occurring fatty acid found in our food supply. 
Mycogen Corporation has estimated the potential worst case dietary exposure of 
pelargonic acid beyond existing natural background levels after an application 
of Scythe Herbicide between grape vine rows. The commodity grape was selected 
because the use of Scythe Herbicide between grape vine rows is a 
representative and major use pattern intended for the product. In an effort to 
make a worst case scenario for residue calculations, Mycogen has suggested a 
10 percent deposition on the crop, even though such a drift rate will be 
intentionally avoided by the grower because crop damage may result. Drift 
deposition would likely be less than 1 percent of applied spray volume.
The worst case human daily consumption level of pelargonic acid from treated 
grapes has been estimated to be 0.397 mg/kg/day. This exposure dose after 
applications of Scythe Herbicide must be compared to the highest dose level 
tested in the dietary range-finding toxicology study. In this study, a daily 
feeding dose of 1,834 mg/kg/ day (20,000 ppm) did not produce any signs of 
toxicity or abnormalities for a period of 2 weeks.
Exposure to drinking water will be minimal. Scythe Herbicide will not be 
applied directly to water. The proposed label includes applications to dry 
ditches, dry canals, ditch banks, and for use above the water line or after 
draw-down of agricultural irrigation water and ditch systems, industrial ponds 
and disposal systems, and impounded water areas. Taking potential spray drift 
into consideration, the rapid degradation of pelargonic acid to naturally-
occurring background levels in our environment will mitigate the exposure of 
residues to drinking water to insignificant amounts. In addition, the 
degradation of pelargonic acid will ensure that no contamination to 
groundwater will occur.
If residues of pelargonic acid do occur in food or in drinking water, 
information on the metabolism of fatty acids in the body confirms that 
residues of pelargonic acid would present minimal risk to humans. Fatty acids 
are digested in mammalian systems through normal metabolic pathways. While 
pelargonic acid is not as widespread in our diet as other fatty acids, the 
only difference is that most dietary fatty acids have even-numbered carbon 
chains and are ingested initially in the form of triglycerides. It is likely 
that pelargonic acid, when it is absorbed from the gastrointestinal tract into 
the blood, would be treated little differently from the free fatty acids 
released from adipose tissue.
Non-dietary exposure of pelargonic acid will be mitigated through the use of 
proper personal protective equipment. For non-occupational uses or exposure to 
sites not associated with food or drinking water, data on the natural 
occurrence and rapid microbiological degradation of pelargonic acid in the 
environment confirms that exposure will be minimal. EPA has waived all 
environmental fate data requirements for the current registration of Scythe 
Herbicide. 
E. Cumulative Exposure
No cumulative exposure through other pesticides and substances with common 
mode of toxicity is expected. Pelargonic acid has a unique mode of action. 
Residues will not increase or sustain as a result of exposure to other 
materials. Pelargonic acid will degrade by microbial action to background 
levels over a period of 24 - 48 hours regardless of contact with substances 
either through pesticide tank mixing or exposure to other chemical residues in 
the environment. Normal use patterns will not lead to accumulation of 
pelargonic acid in the environment.
F. Safety Determination
Mycogen believes that the use of pelargonic acid as a naturally- occurring, 
lower toxicity, environmentally compatible material fits with EPA's objective 
to register reduced risk pesticides. The common dietary intake of the U.S. 
population includes low concentrations of naturally-occurring fatty acids, 
including pelargonic acid. The rapid environmental breakdown of pelargonic 
acid will significantly decrease any residues as a result of applications from 
Scythe Herbicide. Mycogen believes that under worst case exposure 
calculations, and based on established toxicology data, any increased levels 
of pelargonic acid will present no adverse effects to the consumer. 
Mycogen believes that a determination of safety for infants and children can 
be made due to the insignificant exposure expected beyond naturally-occurring 
background levels, the fact that fatty acids are digested in mammalian systems 
through normal metabolic pathways, and the toxicology data base concludes that 
pelargonic acid is practically non-toxic when administered orally. The 
developmental toxicity screen study in rats produced a NOEL of 1,500 mg/kg/day 
(only dose tested), and no evidence of maternal or developmental toxicity was 
seen. 
G. Existing Tolerances
Pelargonic acid is exempt under 40 CFR 180.1159 from the requirement of a 
tolerance when used as a blossom thinning agent on apple and pear. Pelargonic 
acid has been added to the Food and Drug Administration's list of approved 
chemicals that may be safely used in washing or to assist in the lye peeling 
of fruits and vegetables in concentrations of up to 1 percent (21 CFR 
173.315). The same use is cleared by the United States Department of 
Agriculture under the USDA List of Authorized Substances, 1990, 7 CFR 5.14, 
Fruit & Vegetable Washing Compounds. In addition, pelargonic acid is cleared 
by the Food and Drug Administration as a sanitizer solution to be used on 
food- contact articles [21 CFR 178.1010(b) (42)], or as a synthetic food 
flavoring agent and adjuvant (21 CFR 172.515). 
II. Administrative Matters
Interested persons are invited to submit comments on this notice of filing. 
Comments must bear a notation indicating the document control number, [PF-
685]. 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 of filing under docket number 
[PF-685] (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 Hwy., 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 notice of filing, 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 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, Agricultural commodities, Pesticides and pests, 
Reporting and recordkeeping requirements. 
Dated: January 16, 1997.
Flora Chow, Acting Director
Biopesticides and Pollution Prevention Division
Office of Pesticide Programs
[FR Doc. 97-1753 Filed 1-23-97; 8:45 am] 
[Federal Register: January 24, 1997 (Volume 62, Number 16)] [Notices]
[Page 3696-3698]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]