The following pesticides have been identified as most likely to be found on kitchen floors. They are listed in order of degree of presence found in test results:

1. Permethrin (found in 89% of homes tested)
   A general use pesticide for residential and agricultural applications, and an insecticide found in some head lice treatments, pet flea and tick products and other insect repellents. Permethrinis a neurotoxin. The U.S. EPA has classified permethrin as a carcinogen because it causes lung tumors in female mice and liver tumors in mice of both sexes.
2. Chlorpyrifos (found in 78% of homes tested)
   Chlorpyrifos is a potent nerve poison which has been commonly used for decades as an insecticide for home use and as a termiticide in new home construction. Chlorpyrifos was sold as Dursban until 2001.
3. Chlordane (found in 74% of homes tested)
   A pesticide similar to DDT, Chlordane was used on agricultural crops and residential lawns, and was widely used to eradicate termites from homes. Chlordane is a cumulative poison which absorbs through the skin, and long-term exposure may result in severe liver damage. It was banned for all uses in the US in the 1980s due to environmental and human health concerns.
4. Piperonyl butoxide (found in 52% of homes tested)
   PBO is a pesticide synergist. It does not, by itself have pesticidal properties. However, when added to insecticide mixtures, typically pyrethrin, pyrethroid, and carbamate insecticides, their potency is increased considerably. PBO formulations are used to kill wasps, ants, fleas and ticks, lice and other pests. While toxic to aquatic species, its oral and dermal toxicity in mammals is considered to be low.
5. Cypermethrin (found in 46% of homes tested)
   A synthetic pyrethroid insecticide found in some Raid products and other ant and roach killers. Pyrethroids like cypermethrin may cause adverse effects on the central nervous system. New studies in animals and humans show that pyrethroids can alter the production of hormones and harm sperm production.
6. DDT (found in 42% of homes tested)
   DDT is an insecticide widely used for decades to kill mosquitoes and other insect pests. DDT was banned in 1972. Studies in rats have shown that DDT and DDE, a breakdown product of DDT, can mimic the action of natural hormones and in this way affect the development of the reproductive and nervous systems. The EPA has determined that DDT and DDE are probable human carcinogens.
7. Fipronil (found in 40% of homes tested)
   A broad-spectrum insecticide used especially for ants and cockroaches, and for topical flea control on dogs and cats. Fipronil is the active ingredient in some Frontline, Maxforce, and Combat products. It is also the active ingredient of Termidor, used as a barrier treatment for termites. There have been very few studies undertaken with human subjects.
8. Diazinon (found in 35% of homes tested)
   Classified as an organophosphate, Diazinon is one of the most common pesticides used on lawns. As an insecticide it is used widely to kill ants, roaches and other pests, until household use was banned in 2004. Diazinon is classified as moderately to practically nontoxic to small mammals on an acute oral basis. It is highly toxic to birds, bees, fish and marine invertebrates.

It should be noted that toxic effects to humans are linked to the amount of exposure to these pesticides, and these residual amounts found in homes surveyed are less likely to harm people and pets than results reported in lab studies may indicate. However, even a cursory review of the toxicity of these pesticides should alert the consumer to use discretion in deciding how to deal with insect pests in the home environment.