Prenatal Origins of Endocrine Disruption

Critical Windows of Development

CHLORPYRIFOS

What is chlorpyrifos?

Chlorpyrifos is a chlorinated organophosphate insecticide, acaricide and miticide. It is used to control cutworms, corn rootworms, cockroaches, grubs, flea beetles, flies, termites, fire ants, mosquitoes, and lice. It is used as an insecticide on grain, cotton, fruit, nut and vegetable crops. It is also used on golf courses and as a non-structural wood treatment.

Chlorpyrifos is a white crystal-like solid with a strong odor. It sticks tightly to soil particles and does not mix well with water. It is often combined with oily substances for application on crops or animals. It is broken down by sunlight, bacteria or other chemical processes.

In 2000, the U.S. EPA and Dow AgroSciences agreed to stop the sale of most home uses for chlorpyrifos because of health risks, primarily to children, although millions of pounds continue to be applied annually for commercial uses in the U.S.

How does chlorpyrifos get into our bodies?

Chlorpyrifos can be ingested through the mouth, inhaled through the lungs or absorbed through the skin. When chlorpyrifos spray or dust is inhaled, it passes quickly into the blood. While it may enter the body through the skin, the amount that gets through the skin is relatively small. However skin exposure presents a greater health risk for infants because of the texture of their skin and because infants lying or crawling on an area sprayed with chlorpyrifos may have a greater amount of their skin exposed to chlorpyrifos.

Chlorpyrifos has a relatively short biological half-life (roughly 24 hours in blood and 60 hours in fat). It does not accumulate in the body, but transforms to chlorpyrifos-oxon, which is about 3000 times more potent against the nervous system. Chlorpyrifos usually degrades quickly in the environment but low levels may persist for a long time after application, depending on environmental conditions.

Where can I find more information on chlorpyrifos?

For more information on chlorpyrifos see the Agency for Toxic Substances and Disease Registry website.