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chlorpyrifos-methyl Chemical Fact Sheet 6/86






                            CHEMICAL FACT SHEET FOR:
                               CHLORPYRIFOS-METHYL

FACT SHEET NUMBER:  57

DATE ISSUED:  JUNE 30, 1985

                        1. DESCRIPTION OF CHEMICAL

- Generic Name: 0,0-dimethyl 0-(3,5,6-trichloro-2-pyridyl) 
- Common Name:  chlorpyrifos-methyl 
- Trade Name:  Reldan 
- EPA Shaughnessy Code:  059102 
- Chemical Abstracts Service (CAS) Number:  5598-13-0 
- 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, wheat, and grain
  sorghum intended for storage, empty grain storage bins, and equipment. 
- Types of formulations:  Emulsifiable concentrate and dusts. 
- Types and methods of application:  Spray and dusts 
- Application Rates:  1.4-5.0 oz. active ingredient/1,000 bushels of
  grain 1% spray or 2-3% dust to grain equipment and storage walls/
  floors. 
- Usual carriers:  Petroleum solvents and usual clay carriers.

                          3. SCIENCE FINDINGS

Chemical Characteristics

- Physical state:  granular crystalline solid 
- Color:  white 
- Odor:  mild mercaptan 
- Molecular weight:  322.6 
- Melting point:  45.5-46.5 degrees C. 
- Vapor pressure:  7.40 x 10(-7) mm Hg at 0 C. 
- Solubility in various solvents:  Solubility = g/100 g of solvent at
  24 degrees C 
  - Water, 0.0004; acetone, 640; benzene, 520; ethyl alcohol, 30;
    chloroform, 350

Toxicological Characteristics

- Acute oral LD50:  1530 mg/kg, Toxicity Category III 
- Acute dermal LD50:  greater than 2000 mg/kg, Toxicity Category III 
- Primary dermal irritation:  slight irritant, Toxicity Category III 
- Primary eye irritation:  Slight irritant--corneal opacity persisted
  for seven days. Toxicity Category III
- Skin sensitization:  positive
- Acute inhalation:  0.67 mg/l, Toxicity Category II
- Neurotoxicity:  Not an acute delayed neurotoxic agent at doses up to
  500 mg/kg/day
- 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).
- Reproduction, 3-generation:  Studies adequately demonstrate that
  chlorpyrifos-methyl does not produce reproductive effects. No effects
  were demonstrated at dose levels up to 3.0 mg/kg/day (HDT).
- Metabolism:  The studies suggest that chlorpyrifos-methyl is rapidly
  excreted, and there is no bioaccumulation.
- Mutagenicity:  Data gap. These data are to be submitted in June of
  1985.

Physiological and Biochemical Behavioral Characteristics

- Mechanism of pesticidal action:  An insecticide which is active by
  contact, ingestion, and vapor action, and causes phosphorylation of
  the acetylcholinesterase enzyme of tissues, allowing accumulation of
  acetylcholine at cholinergic neuro-effector junctions (muscarinic
  effects), and at skeletal muscle myoneural 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 heartbeat,
  pulmonary edema, and sweating. Continual absorption 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
  chlorpyrifos-methyl is adequately defined. A tolerance for stored
  grain has been established.	-~

Environmental Characteristics

- This use pattern precludes exposure to the environment.  Therefore,
  most environmental effects are uncharacterized.

Ecological Characteristics

- Avian acute oral LD50:  mallard duck, 1590 mg/kg
- Avian dietary LC50:  mallard duck, 5620 ppm; bobwhite quail, 2010 ppm
- Freshwater fish LC50: coldwater fish (rainbow trout), 0.014 ppm;
  warmwater fish (bluegill sunfish), 0.88 ppm
- Acute freshwater invertebrates:  Daphnia, 1.08 ppb

Tolerance Assessment

- The tolerance for chlorpyrifos-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 products is 0.327
  mg/day, and the occupied ADI is 54% for the average U.S. population.
  The traditional system for figuring the TMRC gives an occupied ADI of
  190%.

Summary Science Statement

- Chlorpyrifos-methyl is an organophosphate compound with moderate acute
  toxicity to both humans and wildlife species. The registered use
  precludes exposure to wildlife.

                     5.  SUMMARY OF MAJOR DATA GAPS

No major data gaps except 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 M Street S.W.
Washington, DC  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 THIS CHEMICAL INFORMATION FACT 
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL 
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.