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Environment^ Prciefi'i O^'-ci c' Peciiao«- Proo'am: ITS 76&C
A0enc> Wathirwior DC 2W6C
&EPA Pesticide
Fact Sheet
Name of Chemical: talnphM_.thyl (Ojthlm;
RedSOn for Issuance: Issuance of Guidance Document
Date Issued: 9/30/66
Fact Sheet Number 100
1. Description of Chemical
-Generic Name: O,O-dimethyl-s-((4-oxo-l,2,3-benzotriazin-
3(4H)-yl)methyl] phosphorodithioate
-Common Name: Azinphos-methyl
-Trade Names: metiltriazotion, carfene, cotion-methyl,
gusathion, gusation-M, guthion, Bay 9027,
Bay 17147, R-1582
-EPA Snaughnessy Number: 058001
-Chemical Abstracts Service (CAS) Number: 86-50-0
-Year of Initial Registration: 1956
-Pesticide Type: insecticide, Acaricide, Molluscicide
-Chemical Family: Organophosphate
-U.S. and Foreign Producers: Bayer AG (Federal Republic of
Germany), Makhteshim Chemical Co. (Israel), and Mobay Chemical
Corporation (U.S.) and Aceto Chemical Company.
2. use Patterns and Formulations
-Application sites: fruit and field crops, vegetables, tobacco,
ornamentals and forest trees
-Types and methods of application: folaar (by ground or aerial
equipment), ULV foliar application, soil application, transplant
water application
-Application rates: 0.047 to 10.35 lb a.i./A
-Types of formulation: technical, formulation intermediate,
dust, granular, wettable powder, emulsifiable concentrate,
flowable concentrate, soluble concentrate
-Usual carriers: Confidential Business Information
-All liquid formulations with concentrations of 13.5% or greater
are currently classified as restricted use chemicals
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3. S:ier.Ce Finoir.
Chemical Characterisitics :
Technrcaiirinphos—thetmyl is a yellow—browi solid witr. a
melting point at around 63°C, that decomposes at elevatec
temperatures and is soluble in most organic solvents. Tne
empirical formula is C 10 H 12 N 3 0 3 PS 2 and the molecular weight
is 317.1.
Toxicology Characterisitics
—Acute oral: 4.4 mg/kg (rat), Toxicity Category I, highly toxic
—Acute dermal: 200 mg/kg (rat), Toxicity Categoty I, highly toxic
—Primary Eye Irritation: Data gap.
—Acute Inhalation: Data gap.
—Primary Skin Irritation: Data gap.
—Skin Sensitization: Data gap.
—Major Routes of Exposure: Handling of the concentrated
pesticide and airblast application produce the largest exposure
per pound of azinphos—methyl handled. Human exposure to
azinphos—methyl from handling, application, and re—entry
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opecati0n WOUIO D mir.irrized by tne use ot respirators and
protective c1otflir ;.
—Oncogenicity: A mouse oncogenicity study showed that no
increased incidence of tumors could be attributed to exposure
to azinphos—methyl. A rat oncogenicity study, that was
found to be uacceptable upon re—evaluation, showed that male
rats developed tumors of the pancreatic islets and of the
follicular cells of the thyroid. Because of the wide range of
spontaneous incidence of these tumors in Osborne—Mendel rats,
the Agency concludes that there is no clear link between the
development of tumors to the administration of azinphos—methyl,
the Agency is requiring that a rat oncogenicity study be
conducted and submitted.
—Metabolism: Data gap.
—Teratology: Data gap.
—Reproduction: Data gap.
—Mutagenicity: Data gap.
physiological and Biochemical Characteristics
—Mechanism of pesticidal Action: Cholinesterase inhibition
by all routes of exposure.
—Metabolism and persistence in plants and animals:
Radiolabeled azinphos—rnethyl residues are absorbed through
the roots and translocated to the shoot of hydroponically
treated plants. Available data indicate that azinphos—methyl
is relatively persistent on leaf surfaces and is gradually
degraded to polar metabolites. Although the submitted
studies are not adequate to assess the nature of azinphos—methyl
in animals, metabolites of azinphos—methyl were identified
in chicken excreta and rat urine.
Environmental Characteristics :
—Available data indicate that azinphos—methyl exhibits both
low soil mobility and low leaching potential in a variety of soil
types. Leaching studies indicate a low potential for leaching
of azinphos—methyl residues to groundwater. In sandy soils
azinphos—methyl dissipates in the field fairly rapidly and is
metabolized by microorganisms.
The half—life of azinphos—methyl in a non—sterile soil is
21 days under aerobic conditions and 68 days under anaerobic
conditions. It is more stable in sterile conditions with a
half—life of 355 days. Under aerobic conditions the following
azinphosmethyl metabolites were detected: oxygen analog
residues, mercaptomethyl benzazimide, benzazimide, hydroxymethyl
benzazimide, and bis—methyl benzazimide sulfide. Benzazirnide
and hydroxymethyl benzazimide, were identified as the major
degradation products resulting from hydrolysis. Available
photodegradatiOn data are inadequate to assess the
photodecompositiOfl of azinphos—methyl.
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—Re—entry: Treated areas n.ay not be re—entered for at. icas:
24 hours unless protect1v - clothinc is worr..
Ecological Characteristics
—Acute avian oral toxicity: Supplemental data indicate an LD 5 O
of 136 mg/kg body weight for mallard ducks, 60—120 mg/kg for
bobwhite quail, 74.9 mg/kg for pheasant, and 84.2 mg/kg
for chukar. (Moderately toxic for all species tested).
—Avian dietary toxicity: LC 50 = 488 ppm for bobwhite quail
(highly toxic), LC 50 639 ppm for Japanese quail (moderately toxic),
and LC 50 = 1940 ppm for mallard duck and 1821 ppm for ring—necked
pheasant (slightly toxic).
—Freshwater fish acute toxicity (LC 50 ): Available data
place azinphos—methyl in the range from very highly toxic to
moderately toxic (LD 50 values of 0.36—4,270 ug/1, depending
on species tested with most values in the very highly
toxic range (less than 100 ug/lfl.
—Freshwater aquatic invertebrate toxicity: 0.13—56 ug/l, depending
on the species tested (very highly toxic).
Tolerance Assessment
—Tolerances have been established for residues of azinphos—methyl
in a variety of raw agricultural commodities in meat, fat and
meat byproducts (refer to 40 CFR 180.154 and 4OCFR 180.154a. for
listing of tolerances), and in processed food (21 CFR 193.150) and
and feed (21 CFR 561.180).
—The Agency is unable to complete a full tolerance assessment for
the established tolerances due to residue chemistry and
toxicology data gaps.
—No Mexican tolerances have been established for azinphos—methyl.
Commodity U.S. Canadian Codex
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Alfalfa 2.0 0.1 2.0
Alfalfa,hay 5.0 —
Almonds 0.3 0.2
Almonds,hul ls 10.3 — 10.0
Apples 2.0 2.0 1.0
Apricots 2.0 2.0 2.0
Artichokes 2.0 0.5 0.5
Bar ley,grain 0.2 0.1 0.2
Barley,stcaw 2.0 0.1
Beans(dry) 0.3 2.0 0.5
Beans(snap) 2.0 2.0 0.5
Birdsfoot Trefoil 2.0 0.1 —
BirdsfootTrefoil,hay 5.0 0.1 —
Blackberries 2.0 2.0 1.0
Blueberries 5.0 2.0 1.0
Boysenberries 2.0 2.0 1.0
Broccoli 2.0 1.0 1.0
Brussels Sprouts 2.0 1.0 1.0
Cabbage 2.0 1.0 0.5
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coirzmod 1 ty
U.S.
Canadian Codex
Catt]e,fat 0.1
Cattle,meat by product 0.1 — —
Cattle, eat 0.1 — —
Cauliflower 2.0 0.5 0.5
Celery 2.0 0.5 2.0
Cherries 2.0 1.0 1.0
Citrus fruits 2.0 2.0 2.0
Clover 2.0 0.1 —
Clover,hay 5.0 — —
Cottonseed 0.5 — 0.2
Crabapples 2.0 — 1.0
Ccanberries 2.0 — —
Cucumbers 2.0 0.5 0.5
Eggplant 0.3 — 0.5
Filberts 0.3 — —
Goats,fat 0.1
Goats,meat by product 0.1
Goats,meat 0.1
Gooseberries 5.0 — —
Grapes 5.0 5.0 4.0
Grass,pasture 2.0 0.1 —
Grass,pasture,hay 5.0 —
Horses,fat 0.1 —
Horses,rneat by products 0.1 — -
Horses,meat 0.1 — —
Kiwi fruit 10.0 0.4 4.0
Loganberries 2.0 2.0 1.0
Melons 2.0 — 2.0
Nectrines 2.0 1.0
Nut,Pistachio 0.3 — —
Oats,grain 0.2 0.1 0.2
Oats,straw 2.0 — —
fliOQB4i rOe1 : 2-0 j Y C • 5
Pars]ey(leaves) 5.0 — 0.5
Parsley(roots) 2.0 — D-.5
Peaches 2.0 2.0 4.0
Pears 2.0 2.0 1.0
Peas,b lack—eyed 0.3 — 0.5
Pecans 0.3 — —
Peppers 0.3 0.2 0.5
Plums 2.0 1.0 1.0
Potatoes 0.3 0.1 0.2
Quinces 2.0 2.0 1.0
Raspberries 2.0 2.0 1.0
Rye,grain 0.2 0.1 0.2
Rye,straw 2.0 0.1 —
Sheep,fat 0.1 —
Sheep,meat by product 0.1 —
Sheep,meat 0.1 —
Soybeans 0.2 0.2
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Com1T odity U.S. Car.adiar. Co e>
Spinach 2.0 2.0 0.5
Strawberries 2.0 1.0 1.0
SugatCafle 0.3 — —
Tomatoes 2.0 1.0 0.5
Walnuts 0.3 0.1 —
Wheat,graln 0.2 0.1 0.2
Wheat,straw 2.0 0.1 —
Milk 0.04 — —
Soybean oil 1.0
Dried citrus 5.0
Sugarcane bagasse 1.5
The data for azinphos—iuethYl residues in or on potatoes, parsley,
pistachios, sugarcane bagasse and sugarcane are adequate to support
the respective established tolerances.
Data are not adequate to support the established tolerance
for residues in or on onions, celery, spinach, broccoli,
Brussels sprouts, cabbage, cauliflower, beans, soybeans,
peppers, tomatoes, cucumbers, melons, citrus fruit, apples,
apricots, cherries, nectarines, peaches, plums, blackberries,
blueberries, cranberries, grapes, strawberries, almonds,
almond hulls, filberts, pecans, walnuts, wheat grain, wheat
straw, pasture grass, altalf a, clover, artichokes, cottonseed,
kiwi fruit, eggplant, crabapples, pears, quices, boysenberries,
loganberrieS, raspberries, oat grain, rye grain, barley
grain, oat straw, rye straw, barley straw, birdsfoot trefoil,
soybean oil, and dried citrus pulp.
A Provisional Limiting Dose (PLO) based on a 2 year dog feeding
study has been established using a uncertainty factor of 100.
The Maximum permissible Intake (MPI) is 0.075 mg/kg for a 60 kg.
person. The Theoret4.cal.- Ma.x.imum Residue Cont ributiOn (TMRC)
to the human diet from the existing tolerances is 0.6678 mg for
a 1.5 kg diet which is 899% of the MPI. (This value is greatly
inflated when compared to actual dietary residues expected in
practice, and is due solely to the additional 10—fold uncertainty
factor applied for the reduced data base and two—fold increase in
sensitivity of the dog compared to that of the rat). When
the required chronic feeding studies are submitted, the PLD
and TMRC will be re—evaluated.
—Reported Pesticide Incidents: The pesticide Incident Monitoring
System (PIMS) reported on azinphos—methYl from 1966 through 1979.
The 1981 report is the latest one available, which cites
71 incidents associated with human injury. There was one
fatality which was a confirmed suicide. The PIMS report
cited one bird kill and 29 incidents involving fish and other
aquatic organisms. For the period 1978—1985, seven additional
fish kills, citing azinphos—methyls alone, were obtained at the
Agency’s Office of Water.
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4. Sumr ary of Reoulatory Positior
A. The Agency is requiring extensive field monitoring
data to better define the extent of exposure and
hazard to wildlife.
B. No new tolerances or new food uses will be considered
until the Agency has received data sufficient to
assess existing tolerances ‘jar azinphos-.methyl.
C. The Agency is concerned about the potential for human
poisonings (cholinesterase inhibition) from the use of
azinphos.—methyl. The Agency will continue to restrict
all liquid formulations of azinphos—methyl with gttdi.er
than 13.5% a.i. In addition, registrants must either
classify all products for restricted use (due to acute
toxicity) or submit dermal and inhalation data to
support the appropriate toxicity category.
D. Revised Protective clothing statements are required to
be included on the labels of azinphos—methyl end—use
products.
E. The Agency has concluded that data are not adequate to
determine the oncogenic potential of azinphos—methyl
and is requiring numerous toxicology studies mentioned
below.
F. The Agency is requiring that endangered species labeling
be added to labels for certain azinphos—methyl uses.
G. A 24 hour re—entry interval, previously established
under 40 CFR 170.3 (b)(2) will remain in effect.
H.. The Agency is imposing an interim rotational crop
restriction of 6 months for root crops and 30 days -
for all other registered crops until the required
crop rotation data are submitted.
5. Summary of Major Data Gaps
—Additional crop residue studies on various commodities and plant
and animal metabolism studies are required to support existing
tolerances.
—The following studies are required to assess the toxicological
characteristics of technical azinphos—methyl:
Acute inhalation, Delayed Neurotoxicity,
Oncogenicity! Chronic testing in rat, Teratology, Reproduction,
Mutagenicity, and General tietabolism.
—The following data are required to fully characterize
azinphos—methyl’s environmental fate: Re—entry data (foliar
dissipation, soil dissipation, derrnal exposure, inhalation exposure),
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Special Testing—Glove Permeability, Photodegradation, Anaerobic
Aquatic, Forestry Dissipation, Rotational Crops (Confined),
Irrigated Crops Accumulated Study, Accumulation in Non—target
Organ isms*
—Additional data are required to assess the impact on wildlife
from the use of azinphos—methyl: acute avian oral toxicity,
wild mammal toxicity, avian reproduction, field testing for
mammals and birds, acute toxicity to freshwater invertebrates,
acute toxicty to estuarine and marine organisms, fish early
life stage, simulated or actual field testing for aquatic
organisms and honey bee toxicity.
—Product chemistry and acute toxicity data are required.
*Data not needed if label clarifications are made.
Contact person at EPA:
Lawrence J. Schnaubelt
Product Manager (12)
Insecticide—Rodenticide Branch
Registration Division (TS—767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M. Street, S.W.
Washington,D.C. 20460
Office location and telephone number:
Room 202, Crystal Mall Building #2
1921 Jefferson Davis Highway
Arlington,va. 22202
703—557—2386
Disclaimer: The information presented in this pesticide
Fact Sheet is for informational purposes only and may not be
used to fufill data requirements for pesticide registration and
reregistration.
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