Parathion methyl, or methyl parathion, is an organophosphate insecticide, possessing an organothiophosphate group. The organophosphate pesticides such as malathion, parathion, and chlorpyrifos irreversibly inhibit acetylcholinesterase. Both methyl parathion and azinphos methyl are organophosphates. Some insecticides, including carbamates and organophosphates such as dichlorvos, malathion and parathion, are nerve agents. It is an organophosphate oxon, and the active metabolite of the insecticide parathion. It is also used in the production of pesticides such as Parathion and Malathion. Tetrachlorvinphos and parathion were classified as "possibly carcinogenic", malathion, and diazinon. Parathion was among the first marketed, followed by malathion and azinphosmethyl. It has been linked to specific OP pesticides such as parathion, methylparathion, and dichlorvos. Parathion methyl is used as an insecticide on crops, including cotton. They died after eating a poisoned breakfast containing the organic phosphate pesticide parathion. Parathion is used as an agricultural pesticide. Parathion acts on the enzyme acetylcholinesterase indirectly. Organophosphates, e.g. parathion, methyl parathion and about 40 other insecticides are available nationally. Parathion methyl has been restricted for many years.