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Fipronil is a broad use insecticide that belongs to the phenylpyrazole chemical family. Fipronil is used to control ants, beetles, cockroaches, fleas, ticks, termites, mole crickets, thrips, rootworms, weevils, and other insects. Fipronil is a white powder with a moldy odor. Fipronil was first registered for use in the United States in 1996.

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Fipronil is used in a wide variety of pesticide products, including granular products for grass, gel baits, spot-on pet care products, liquid termite control products, and products for agriculture. There are more than 50 registered products that contain fipronil.

Fipronil kills insects when they eat it or come in contact with it. Fipronil works by disrupting the normal function of the central nervous system in insects. Fipronil is more toxic to insects than people and pets because it is more likely to bind to insect nerve endings.

People can be exposed to chemicals in four ways: contacting their skin, contacting their eyes, breathing them in, or eating them. Direct contact to the skin or eyes may occur while applying fipronil products. Pets may be exposed to fipronil by products that are applied to their skin for flea and tick treatments. People may also be exposed to fipronil when applying flea and tick products.

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The amount of fipronil taken into the body across the skin depends on the product formulation. Researchers applied a dose of 79% fipronil to the skin of rats and found that less than 1% of fipronil was taken into the body after 24 hours. When test animals have eaten fipronil, between 15 and 33% (goats) and 30 to 50% (rats) of the ingested dose was absorbed by the body. The rest of the fipronil was eliminated in the feces and urine.

"A 143-pound adult would have to eat more than seven eggs in 24 hours to be at risk, according to Germany's health agency," writes David Schrieberg for Forbes, though he adds that the risk is higher for children. "A 36-pound child could be affected by little more than one-and-a-half eggs in that period."

While children may be especially sensitive to pesticides compared to adults, there are currently no data showing that children have increased sensitivity specifically to fipronil. There is no evidence that fipronil or its breakdown products evaporate from soil or water into the air. Fipronil is not well absorbed by plants when it is applied to soil. If fipronil does get into plants, it can partially break down. On plant surfaces, fipronil can be broken down by sunlight.

Source: National Pesticide Information Center