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CAS Number: 62-73-7
Synonyms: DDVP, Vapona
Contaminant Type: Chemical

Dichlorvos is an organophosphate insecticide. Its IUPAC name is 2, 2-dichlorovinyl dimethyl phosphate. It is commonly called DDVP and has a common trade name of Valpona. [495] Because it has a high vapor pressure, its principal use is as a fumigant and fogger. [495] It is commonly used as a fumigant in food storage areas, grain storage areas, barns, animal houses, and greenhouses. [527] It is also used on pest strips and pet flea collars. [602]

Dichlorvos is not regulated by USEPA in drinking water.

It is toxic by ingestion. [527] As it is an acetylcholinesterase inhibitor, it affects the central nervous system. [602] USEPA classifies it as a possible human carcinogen. [602]

The following properties and phenomena suggest dichlorvos will not commonly be detected in water. [602] It has a low organic carbon partition coefficient and is not well sorbed to soil particles suggesting its movement through soil to groundwater. It has a low Henry's constant suggesting it does not volatilize from water. It does not strongly absorb UV light suggesting it will not photodegrade in water. While these properties suggest it will be stable in water, other properties suggest losses in surface waters and ground waters, and suggest it would not commonly be detected in source waters. In water, its hydrolysis half lives are in the order of days at acidic pHs and hours at basic pHs, and its hydrolysis half lives are in the order of weeks at 10 C and days at 30 C. In laboratory studies, its disappearance in soils was linked to Bacillus cereus. In sewage sludge studies, its transformation to dichloroethanol, dichloroacetic acid, ethyl dichloroacetate, and phosphate was related to Pseudomonas aeruginosa and other Pseudomonas species.

It enters water via manufacturing, landfill leachates, spills, and leaks. [528] It may be formulated with a variety of other pesticides. In water, dichlorvos may be detected as a result of the breakdown of trichlorfon, another organophosphate insecticide. [602] All of the 1430 National Priorities List hazardous waste sites were not sampled for dichlorvos, but it was detected at three of the sites. [528] Among those three sites, it was detected in only one of the groundwaters. [602] In USEPA's National Pesticide Survey of Drinking Water Wells, dichlorvos was not detected. [602]

In addition to those listed above, other transformation products of dichlorvos in water have been reported as dimethyl phosphate, dichloroacetaldehyde, 1, 1-dichloroethenol, and dimethyl phosphoric acid. [602]

Date of Literature Search: March 2007

495 Extoxnet; 1996; Extoxnet pesticide information profiles; http://extoxnet.orst.edu/; As posted on July 26, 2007. Extoxnet is a cooperative effort of University of California-Davis, Oregon State University, Michigan State University, Cornell University, and the University of Idaho.
527 U.S. Department of Health and Human Services, ATSDR; 1997; ToxFAQs for Dichlorvos; http://www.atsdr.cdc.gov/tfacts88.pdf; As posted on August 24, 2007. ATSDR, Division of Toxicology, Atlanta, GA.
528 U.S. Department of Health and Human Services, ATSDR; 1997; Public Health Statement for Dichlorvos; http://www.atsdr.cdc.gov/toxprofiles/phs88.html; As posted on August, 24, 2007. U.S. Department of Health and Human Services, ATSDR, Division of Toxicology, Atlanta, GA.
602 Agency for Toxic Substances and Disease Registry; 2007; Dichlorvos, Part 5: Potential for Human Exposure; http://www.atsdr.cdc.gov/toxprofiles/tp88-c5.pdf; As posted on August 29, 2007. ATSDR, US Department of Health and Human Services, Centers for Disease Control and Prevention, Atlanta, GA.

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