Chlorpyrifos is an insecticide that has been widely used to control cockroaches, fleas, termites and to control crop pests. In 1997, chlorpyrifos was withdrawn from most indoor and pet uses. Chlorpyrifos is a white crystal-like solid with a strong odour. 
Chlorpyrifos enters the environment through direct application to crops, lawns and domesticated animals. They may also enter the environment through spills and the disposal of chlorpyrifos waste.
It has a low water solubility (0.7 mg/l) and a high tendency to adsorb to particles and soils. Therefore it's unlikely to end up in the marine ecosystem. It has a high volatility causing it usually to evaporate after use, where it will be degraded rapidly. It however only evaporates slowly from water bodies, mainly because chlorpyrifos in water is associated to particles. In water it is slowly hydrolysed and its concentration will be halved in less than 60 days. 
Chlorpyrifos is very toxic for crustaceans, especially amphipods which die at concentrations above 0.1 µg/l. Some fish species start dying at concentrations above 1 µg/l while other can tolerate concentrations above 500 µg/l.  In humans, chlorpyrifos can cause cholinesterase inhibition; it can overstimulate the nervous system causing nausea, dizziness, confusion, and at very high exposures respiratory paralysis and death. Reregistration Eligibility Decision for Chlorpyrifos
Environmental standards and legislation