Agent Name


CAS Number




Major Category



75 SP; Acephat; Acephat [German]; Acephate, technical; Acetamidophos; Acetylphosphoramidothioic acid O,S-dimethyl ester; Chevron Orthene; Chevron RE 12,420; ENT 27822; N-(Methoxy(methylthio)phosphinoyl)acetamide; O,S-Dimethyl acetylphosphoramidothioate; O,S-Dimethylacetylphosphoroamidothioate; Orthene; Orthene-755; Ortho 124120; Ortran; Ortril; RE 12420; Phosphoramidothioic acid, N-acetyl-, O,S-dimethyl ester; Phosphoramidothioic acid, acetyl-, O,S-dimethyl ester; [ChemIDplus]


Organophosphate Insecticides


Colorless to white solid; [HSDB] Colorless crystalline solid with a stench; [MSDSonline]


Used as a contact and systemic insecticide for field, fruit, and vegetable crops, forestry, food handling, ornamentals, and household applications; Also used for control of parasites in farm animals; [HSDB] Used in industrial, commercial, and other public and non-agricultural areas; [Reference #1]


May cause cholinesterase inhibition; [ICSC] At doses non-toxic maternally, embryonic development was not adversely effected in mice; High dose studies of mice caused dose-dependent rise of abnormalities in sperm; No human data available; [REPROTOX] Methamidophos (CAS# 10265-92-6) is an environmental degradate; "Laboratory data indicate that acephate and its degradate may pose chronic risk to mammals by affecting the reproductive capacity of mammals (i.e., by reducing the viability of pups and body weight); however, there are no field data to corroborate this." [Reference #1] 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 "Methamidophos."


Banned in the EU for use as a biocide and agricultural insecticide; [eChemPortal: ESIS]

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

1.7E-6 mm Hg

Lethal Concentration

LCLo (mice) = 2,200 mg/m3/5h

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: