Chlorfenvinphos is an insecticide used to control insect pests on livestock. It was also used to control household pests such as flies, fleas, and mites. The pure chemical is a colourless liquid with a mild odour. 
Chlorfenvinphos was introduced in the US in 1963 where it was used until 1991. No information is available about the volumes in which it was used.
Chlorfenvinphos enters the environment from run-off after rainfall and leaching from hazardous waste sites. After it has leached, it may be present in the soil and underground water. It has a water solubility of 130mg/l and a moderate tendency to adsorb to particles. In water it is relatively stable, it is only slowly hydrolysed, but some biodegradation might occur by micro-organisms.
It is very toxic for fishes: acute toxicity concentrations range, depending on the species, between 25 µg/l and 1 mg/l. Zooplankton are even more vulnerable, some species die at concentrations above 0.4 µg/l. 
Environmental standards and legislation