The newly estimated hazards of chlorpyrifos are based on experiments showing the substance can cause brain damage in fetal rats, not on human studies. The pesticide is a member of the organophosphate family of compounds, whose most potent cousins include nerve gases used as chemical weapons. Dow Chemical Co. About 800 consumer products contain the compound. The EPA has determined that the compound poses no imminent threat to public health, and consequently won't order a recall of products containing it. For example, some dog and cat flea collars now contain insecticides called pyrethroids instead of chlorpyrifos.
Many exterminators use chemical baits rather than pesticides to rid houses of termites.
Several environmental and public health interest groups have campaigned hard against the compound, calling it one of the most hazardous pesticides in general use. Normally, EPA sets a safe exposure level for a pesticide such as chlorpyrifos at one one-hundredth of the maximal concentration at which there are no detectable effects on an adult animal. Such a stringent level effectively rules out home use of chlorpyrifos because consumers couldn't use the chemical without bumping up against that very low ceiling. Also troubling to some scientists is chlorpyrifos's staying power and its ability to move from one surface to another. One study showed that when it is sprayed in the home, some becomes volatile and settles on rugs, furniture and toys, from which it is later released, said David Wallinga, a physician and scientist with the Natural Resources Defense Council, a Washington environmental group.