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Chlorpyrifos is the active ingredient in a wide range of insecticides formulated to control ants, spiders, ticks, lice, fleas and locusts...

It is also used in cockroach baits and is registered for the control of subterranean termites (but is restricted for pre-construction use). It is an organophosphate (OP) which also contains chlorine, and it is more persistent than some other OPs. Its indoor use was banned in the US in 2000 due to unacceptable risks to children's brain development. It is still registered for use in Australia (though it is under review by the NRA), so it is advisable to avoid all products containing chlorpyrifos such as cockroach baits, surface sprays and pet treatments.

Health effects
See also Organophosphates. Chlorpyrifos is less hazardous than other OPs because it is less readily absorbed through the skin, but it is very toxic when ingested. It is classed as a Schedule 6 poison. Some questions regarding its long-term effect on the peripheral and central nervous system have been raised. Some formulations contain large proportions of chlorinated solvents which are themselves toxic. Protective clothing and a respirator should be worn when spraying or handling liquid formulations. Pressure-pack or trigger-pack products containing chlorpyrifos are not recommended because of the danger of inhaling the aerosol. It is not recommended for indoor use. If chlorpyrifos is swallowed, vomiting should be induced, and contaminated skin should be washed with soap and warm water.

Environmental effects
The persistence of chlorpyrifos in soil is greater than for other OPs and depends on the type of soil and the temperature. When injected into the soil for termite treatment it has been found to persist for seven to 10 years. It is highly toxic to fish and other aquatic organisms and should not be used near water bodies into which it could be carried by run-off or spray drift. It is very toxic to bees.

Use sticky traps for crawling insects in the home, non-chemical physical treatments to control termites and herbal insect repellents for animal pest treatment; or pyrethrum or pyrethroid sprays as less toxic chemical alternatives. See also Termite treatments.