United States Office of Pesticides and Toxic Substance*
Environmental Protection Office of Pesticide Programs (TS-766CI
Agency Washington, DC 20460
xvEPA Pesticide
Fact Sheet
Name of Chemical: chlorpyrifos-methyl
Reason for Issuance:
Date Issued: June 30f 1985
Fact Sheet Number:
57
1. DESCRIPTION OF CHEMICAL
* Generic Name: 0,0-dimethyl O-(3.5,6-trichloro-2-pyridyl)
phosphorothioate
Common Name: Chlorpyrifos-methyl
Trade Name: Reldan
EPA Shaughnessy Code: 059102
Chemical Abstracts Service (CAS) Number: 510.0
year of Initial Registration: 1985
Pesticide Type: Insecticide
Chemical Family: Organophosphate
U.S. Producer: Dow Chemical U.S.A.
2. USE PATTERNS AND FORMULATIONS
Application Sites: Grains of rice, barley, oats,
pp wheat, and grain sorghum intended
for storage, empty grain storage
bins, and equipment.
Types of Formulations: Emulsifiable concentrate and dusts
Types of Methods of Application: Spray and dusts
Application Rates: 1.4-5.0 02. active ingredient/1000 bushels
of grain . . .
1% spray or 2-3% dust to grain equipment
and storage walls/floors
Usual Carriers: petroleum solvents and usual clay carriers
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3. SCIENCE FINDiNGS OF TECHNICAL CHEMICAL
Summary Science Statement
Chiorpyrifos-methyl is an organophosphate compound with
moderate acute toxicity to both humans and wildlife species.
The registered use precludes exposure to wildlife.
Chemical Characteristics
Physical State: Granular crystalline solid
Color: White
Odor: Mild mercaptan
Molecular weight and formula: 322.6 — C 7 H7C 1 3 NO 3 PS
Melting point: 45.5 — 46.5° C
Vapor Pressure: 7.40 x l0 mm Hg at 0° C
Solubility in various solvents: Solubility: g/lOOg of solvent
at 24° C
Water —0.0004
Acetone —640
Benzene —520
Ethyl
alcohol —30
Chloroform—350
Toxicology Characteristics
Acute Oral: 1530 mg/kg, Toxicity Category III
Acute Dermal: greater than 2000 mg/kg, Toxicity Category III
Primary Dermal Irritation: Slight irritant—Toxicity Category
III
Primary Eye Irritation: Slightly irritant—Corneal opacity
persisted for 7 days. Toxicity Category III
Skin Sensitization: Positive
Acute inhalation: 0.67.sng/1,, Toxicity Category II
Neurotoxicity: Not an acute delayed neurotoxic agent at
doses up to 500 mg/kg/day
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Oncogenicity: Not shown to be an oncogen in rat or mouse
studies at dose levels up to 3.0 mg/kg/day
and 9.0 mg/kg/day (highest dosages tested),
respectively
Teratogenicity: The Agency has determined that this chemical
is not teratogenic at levels up to 200 mg/kg!
day in rats and >16 mg/kg/day in rabbits
(highest dosages tested)
ReproductiOfl—3 generation: Studies adequately demonstrate
that chlorpyrifos-rnethyl does not produce reproductive
effects. No effects were demonstrated at dose levels up to
3.0 mg/kg/day (liD?)
Metabolism: The studies suggest that chiorpyrifos—methyl is
rapidly excreted and there is no bioaccumulation
MutagefliCity: Data gap— These data are to be submitted in
3une of 1985
Physiological and Biochemical Behavioral Characteristics
Mechanism of Pesticida] Action: An insecticide which is
active by contact, ingestion, and vapor action and causes
phosphorylatiOfl of the acetyicholinesterase enzyme of tissues,
allowing accumulation of acetylch]oline at cholinergic neuro—
effector junctions (muscariniC effects), and at skeletal
muscle myoneura]. junctions and autonomic ganglia. Poisoning
also impairs the central nervous system function.
Symptoms of poisoning include: headache, dizziness, extreme
weakness, ataxia, tiny pupils, twitching, tremor, nausea,
slow heatbeat, pulmonary edema, and sweating. Continual
absorbtion at intermediate dosages may cause influenza—like
illness which includes symptoms like weakness, anorexia, and
malaise.
Metabolism and Persistence in Plants and Animals :
The metabolism of chiorpyrifos—methyl is adequately defined.
.A tolerance for stored graini as been established.
Environmental Characteristics
This use pattern precludes exposure to the environment. There-
fore, most environmental effects are uncharacterized.
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Ecological Characteristics
Avian acute. oral
Mallard Duck——1590 mg/kg
Avian dtetary:
Mallard duck——5620 ppm
Bobwhite quail—-2010 ppm
Freshwater Fish:
Coldwater fish (rainbow trout)——0.014 ppm
Warmwater fish (bluegill sunfish)—-O.88 ppm
Acute Freshwater Invertebrates:
Daphnia—-l.08 ppb
Tolerance Assessment
The tolerance for chiorpyrifos—methyl has been assessed
according to the new Tolerance Assessment System (TAS).
Under this method of analysis, the TMRC value for stored
grain and grain product is 0.327 mg/day and the occupied
ADI is 54 percent for the average U.S. population. The
traditional system for figuring the TMRC gives an oc-
cupied ADI of 190%.
5. SUMMARY OF MAJOR DATA GAPS
No major data gaps, only mutageniCity studies
6. CONTACT PERSON AT EPA
Jay S. Ellenberger
Product Manager (12)
Insecticide-RodentiCide Branch
Registration Division (TS—767C)
Office of Pesticide Programs
Environmental Protection Agency
401 N Street, S. W. -
Washington. D. C. 20460
Office location and telephone number:
Room 202,-Crystal Mall $2
1921 Jefferson Davis Highway
Arlington. VA 22202
(703) 557—2386
DISCLAIMER: ’The information presented in thls Chemical Information
pact Sheet is -for informational purposes only-end ay notbe used
to-fulfill data requirements for pesticide registration añd
reregistration. -
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