Malthion is an organophosphate insecticide which acts as an acetyl cholinesterase inhibitor. It is a pesticide that is widely used in agriculture, residential landscaping, public recreation areas, and in public health pest control programs such as mosquito eradication. In the US, it is the most commonly used organophosphate insecticide. Applications: Mode of action Non-systemic insecticide and acaricide with contact, stomach and respiratory action. Used to control Coleoptera, Diptera, Hemiptera, Hymenoptera and Lepidoptera in a wide range of crops, including cotton, pome, soft and stone fruit, potatoes, rice and vegetables. Used extensively to control major arthropod disease vectors(Culicidae) in poblic health programmes, ectoparasites (Diptera, Acari, Mallophage) of cattle, poultry, dogs and cats, human head and body lice (Anoplura), household insects (Diptera, Orthoptera), and for the protection of stored grain. Typical application for agricultural uses 0.5-1.25 kg/ha. Phytotoxicity Non-phytotoxic in general, if used as recommended, but glasshouse cucurbits and beans, certain ornamentals, and some varieties of apple, pear, and grape may be injured. Toxicology: Oral Acute oral LD50 for rats 1375-5500 mg/kg (pure), mice 775-3320 mg/kg. Skin and eye Acute percutaneous LD50 (24 h) for rabbits 4100-8800, rats >2000 mg/kg. Inhalation LC50 (4 h) for rats >5.2 mg/l. NOEL In 2 y trials on rats, the only effects seen at 500 ppm (29 mg/kg b.w. daily) was inhibition of cholinesterase in plasma and red blood cells. ADI (JMPR) 0.3 mg/kg b.w. [1997]. Toxicity class WHO (a.i.) III