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CAS Number: 121-75-5
Synonyms: Cekumal, Fyfanon, Malixol, Maltox
Contaminant Type: Chemical

Malathion is an organophosphorous insecticide [733] and has become one of the most widely used groups of pest control chemicals.  Its IUPAC name is dietyl (dimethoxyphospinothioylthio) succinate.

Malathion comes in two forms: a pure form of a colorless liquid and a technical grade solution (brownish-yellow liquid), which contains malathion (> 90%) and impurities in a solvent [738].  It is primarily applied by aerial or ground spraying, and fogging equipment, but is also used in bait-type formulations. The annual use of the malathion in 1994 was reported 3,377,681 pounds, of which 782,434 pounds  were used in the state of California [738].

Malathion is currently not regulated by the USEPA in drinking water.

Malathion interferes with the normal functions of the nervous system. Exposure to high amounts of malathion in the air, water, or food may cause difficulty breathing, chest tightness, vomiting, cramps, diarrhea, watery eyes, blurred vision, salivation, sweating, headaches, dizziness, loss of consciousness, and death. If persons who are exposed to these high amounts are rapidly given apporiatre treatment, there may be  no long-term harmful effects [738].

Malathion has been detected in three rivers, which are the three largest tributaries to the Chesapeake bay. Malathion was identified in 6-16 percent of the water samples collected from the Susquehanna, Potomac, and James rivers in 1992-1993; mean concentrations of malathion in the rivers were 6, 12, and 7 ng/L, respectively. Malathion was detected in the surface waters transecting the Central Valley to the Sierra Nevada mountains at concentrations of 65-83 ng/L [738].

Date of Literature Search: June 2009

733 Chian, E., Bruce, W. and Fang, H.; 1975; Removal of pesticides by reverse osmosis ; Env. Sci. & Tech.; 9:1:52
734 Guivarch, E., Oturan, N. and Oturan, M.; 2003; Removal of organophosphorus pesticides from water by electrogenerated fenton's reagent; Environ. Chem. Lett.; 1:3:165
738 USDHHS; 2003; Toxicological profile for malathion; Toxicological profile for malathion; pp. 167-169. Agency for Toxic Substances and Disease Registry, Division of Toxicology and Environmental Medicine/Applied Toxicology Branch, U.S. Department of Health and Human Services, Atlanta, GA.