The organophosphate pesticides such as malathion, parathion, and chlorpyrifos irreversibly inhibit acetylcholinesterase. Chemical insecticides such as malathion, carbaryl, and acephate can substantially reduce budworm. Some insecticides, including carbamates and organophosphates such as dichlorvos, malathion and parathion, are nerve agents. For scabies either permethrin or malathion is typically preferred. Pesticides that have historically been found to be effective include pyrethroids, dichlorvos and malathion. It is also used in the production of pesticides such as Parathion and Malathion. Parathion was among the first marketed, followed by malathion and azinphosmethyl. Tetrachlorvinphos and parathion were classified as "possibly carcinogenic", malathion, and diazinon. Thiomalic acid forms the backbone of the pesticide malathion. Also derivatives containing the thiophosphoryl group (P=S) include the pesticide malathion. Its mechanism of action resembles that of some commonly used insecticides, such as malathion. A number of topical medications are also effective, including malathion, ivermectin, and dimethicone. Malathion used as a fumigant was not associated with increased cancer risk. Other treatments include lindane, benzyl benzoate, crotamiton, malathion, and sulfur preparations. It does not work for poisonings by cyanide, corrosive agents, iron, lithium, alcohols, or malathion.