Chlorfenvinphos

Chlorfenvinphos is an organophosphorus compound that was widely used as an insecticide and an acaricide. The molecule itself can be described as an enol ester derived from dichloroacetophenone and diethylphosphoric acid. Chlorfenvinphos has been included in many products since its first use in 1963. However, because of its toxic effect as a cholinesterase inhibitor it has been banned in several countries, including the United States and the European Union. Its use in the United States was discontinued in 1991.

The pure chemical is a colorless solid, but for commercial purposes, it is often marketed as an amber liquid. The insecticides, mostly used in liquid form, contain between 50% and 90% chlorfenvinphos. The substance easily mixes with acetone, ethanol, and propylene glycol. Furthermore, chlorfenvinphos is corrosive to metal and hydrolyzes in the environment.

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.

Dermaton was the first registered product containing chlorfenvinphos. It was introduced in the United States in 1963 and was used as an insecticide and acaricide for controlling fleas and ticks on domestic pets and other animals. Between 1963 and 1970, additional uses were registered, including the use as fly spray, surface spray and larvicide. Because of these effects, chlorfenvinphos was often used on farms to control adult flies in dairy barns, milk rooms, poultry houses and yards, and in other animal buildings. Furthermore, it was used to control larval flies in manure storage pits and piles and other refuse accumulation areas around dairies and feedlots. In the early 1980s, chlorfenvinphos was registered for additional uses in a dust formulation for use in dog kennels and in dog collars for the control of fleas and ticks.

Outside the United States, chlorfenvinphos, registered under the trade names Birlane, C8949, CGA 26351, Sapecron, Steladone and Supona, was used as a soil insecticide for controlling root maggots, root worms and cutworms. Chlorfenvinphos was also used against Colorado beetles on potatoes and scale insects and mite eggs on citrus. Furthermore, the compound had the same uses as in the United States.

There is no quantitative information on the total volume of chlorfenvinphos really used as a pesticide in the United States or elsewhere. Since all uses of the chemical in the United States were canceled in 1991, use is likely to have declined, although there are no data showing this trend.

No international regulations exist for the use of chlorfenvinphos, although standards and guidelines have been set to protect people from the possible harmful effects of the toxin. No regulation exists for inhalation exposure, but multiple minimal risk levels (MRL) have been estimated for oral exposure. These data have been developed from lowest observed adverse effect levels (LOAEL) in test rats, based on adverse neurological effects. The acute oral MRL has been established at 0.002 mg/kg/day, while the chronic MRL has been established somewhat lower, at 0.0007 mg/kg/day.

Furthermore, chlorfenvinphos is one of the chemicals regulated under “The Emergency Planning and Community Right-to-Know act of 1986”. This means that owners and operators of certain facilities that manufacture, import, process or otherwise use the chemical, are obligated to report their annual release of the chemical to any environmental media.