Agent Name


Alternative Name

Chlorpyrifos O,O-dimethyl analog

CAS Number




Major Category



Chlorpyrifos O,O-dimethyl analog; Chloropyriphos-methyl; Chlorpyrifos methyl; Chlorpyriphos-methyl [ISO-French]; Dowco 214; Dursban methyl; ENT 27520; M 3196; Methyl chlorpyrifos; Methyl chlorpyriphos; Methyl dursban; Methylchlorpyrifos; Noltran; O,O-Dimethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate (8CI)(9CI); O,O-Dimethyl O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-Dimethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate; OMS-1155; Reldan; Reldan 50 EC; Trichlormethylfos; Tumar; Zertell; [ChemIDplus]


Organophosphate Insecticides


White or amber solid; [HSDB] Colorless solid; [CAMEO]


Used as insecticide, acaricide, and veterinary ectoparasiticide; [Merck Index] Used mainly to protect cereals (including storage); [HSDB] Used as insecticide for stored grains, rice, oil crops, and animal feed; [Reference #1]


A skin irritant; [SAX] May cause skin sensitization; [eChemPortal: ESIS] In a two year feeding study with rats (highest dose level 1 mg/kg/day) no significant adverse gross or histopathological changes were observed as well as no relation to frequency of spontaneous tumors; Effects in a three generation feeding study with rats include inhibition of cholinesterase activity and decreased pup weights in the second and third generation; No significant effects were observed in fertility, gestation, viability, or lactation; No gross or histopathological changes were noted in third generation parental animals; No teratogenic effects observed in a study with rats; [Reference #2] The average of two baseline respective cholinesterase activity determinations three days apart, with no exposures to enzyme inhibiting pesticides for at least 30 days, is recommended for each worker prior to exposure to cholinesterase inhibitors because of large inter-individual differences in published baseline values. To be established at least once a year. Removal from workplace exposures is recommended until the cholinesterase activity returns to within 20% of baseline. [TLVs and BEIs] See "Chlorpyrifos."

Reference Link

EPA Pesticide Chemical Search

Exposure Assessment

Acetylcholinesterase activity in red blood cells = 70% of individual's baseline; Butylcholinesterase activity in serum or plasma = 60% of individual's baseline; Sample at end of shift; [TLVs and BEIs]

Vapor Pressure

4.22E-5 mm Hg

Lethal Concentration

LC50 (rat) > 670 mg/m3/4h

Reference Link

INCHEM JMPR: Chlorpyrifos-methyl

Adverse Effects
Other Poison


Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information


Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap

Occupational diseases associated with exposure to this agent:


Industrial Processes with risk of exposure: