Disclaimer Introduction Chlorpyrifos is an insecticide that is a white crystal-like solid with a strong odor. It does not mix well with water, so it is usually mixed with oily liquids before it is applied to crops or animals. It may also be applied to crops in a capsule form. Chlorpyrifos is widely used in homes and on farms. In the home, it is used to control cockroaches, fleas, and termites; it is also used in some pet flea and tick collars. On the farm, it is used to control ticks on cattle and as a spray to control crop pests. Fate & Transport Chlorpyrifos enters the environment through direct application to crops, lawns, and pets. It may enter the environment in the home and workplace. It may also enter the environment through volatilization, spills, and the disposal of chlorpyrifos waste. Chlorpyrifos sticks tightly to soil particles. It does not mix well with water, so it rarely enters local water systems. Once in the environment, it is broken down by sunlight, bacteria, or other chemical processes. Exposure Pathways Using it to control household pests such as fleas or cockroaches Breathing air outside of homes where chlorpyrifos was applied to the ground around the foundation to control termites Breathing air in a field where chlorpyrifos was sprayed on to crops Touching soil in a field where it was sprayed Breathing air near a waste disposal site which contains chlorpyrifos Health Effects Breathing high levels of chlorpyrifos results primarily on nervous system effects, such as headaches, blurred vision, and salivation. It has also resulted in unstable blood pressure, diarrhea, nausea, and muscle cramps. Ingesting very high concentrations of chlorpyrifos can cause paralysis, seizures, loss of consciousness, and death, while high concentrations can cause dizziness, runny nose, confusion, salivation, and rapid heart rate. It can also cause muscle weakness after the original symptoms have disappeared. It is not known whether chlorpyrifos can affect reproduction or cause birth defects in people. One animal study reported a decrease in the movement of sperm following exposure to chlorpyrifos, but it is not known if people would experience similar effects. It is not known whether chlorpyrifos causes cancer in people. Animal studies have not shown that chlorpyrifos causes cancer. The EPA has determined that chlorpyrifos is a possible human carcinogen. Regulations The EPA requires that spills or accidental releases into the environment of 1 pound or more of chlorpyrifos be reported to the EPA. The EPA also recommends that children not drink water with chlorpyrifos levels greater than 0.03 milligrams per liter of water (0.03 mg/L) for 1-10 days exposure. The Food and Drug Administration (FDA) has set tolerances for chlorpyrifos for agricultural products ranging from 0.05 to 15 parts chlorpyrifos per million parts of food (0.05-15 ppm). Information excerpted from Toxicological Profile for Chlorpyrifos 1996 Agency for Toxic Substances and Disease Registry United States Public Health Service