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Duke Study Confirms Toxicity of Widely Used Pesticide Ingredient

For Immediate Release: 
Thursday, May 31, 2012

Washington, D.C. – In an innovative study, researchers at the Duke University School of Medicine have developed a laboratory screening system for detecting neurotoxic chemicals and successfully tested it on more than 1,400 potential toxicants. The study confirmed the high toxic activity of the chemical piperonyl butoxide, a so-called chemical “synergist” used to increase the potency of more than 700 insecticides, including many for home use.

The testing showed that piperonyl butoxide (PBO) disrupts a biological signaling system that is “critical in neurological development,” the researchers reported in the abstract of their paper, published in the May 2012 edition of the journal Toxicological Sciences. The study found that the disruption of this critical pathway “may be the molecular basis for profound developmental defects in children exposed in utero to PBO.”

“With tens of thousands of chemicals in widespread use with minimal safety testing, the Duke study shines a bright light on the potential hazards of household pesticides," said EWG Senior Scientist David Andrews Ph.D. “This testing model may teach us much about the industrial chemicals that are in our homes. This study underscores why pregnant women should steer clear of handling any household insecticide. These exposures could very well put their unborn babies in contact with these chemicals during the most fragile period of development.”

Piperonyl butoxide is not itself classified as a pesticide, but companies combine it with insecticides to increase their potency. PBO came into widespread use when the Environmental Protection Agency phased out chlorpyrifos and other organophosphate pesticides more than a decade ago after determining that they posed a risk to children’s health. Many current products contain five to ten times more PBO than the pesticide itself. PBO is listed among the top 10 chemicals detected in indoor dust, often a significant route of exposure to children.

Only in the last few years have the risks of exposure to piperonyl butoxide become evident. In 2011, researchers at Columbia University’s Mailman School of Public Health found that infants whose mothers had been exposed to low levels of PBO in air during pregnancy had impaired cognitive and motor development by the age three.

“We were concerned when our study confirmed that PBO disrupted neurological development pathways – especially given the widespread use of this chemical in American homes,” said Wei Chen PhD, assistant professor at the Duke School of Medicine and an author of the new study. “Our study demonstrates the need for additional research and evaluation of the safety profile of PBO as a pesticide synergist and the value of high- throughput screening in assessing the potential toxicity of chemicals.”

Common household insecticide products that contain piperonyl butoxide include, among others, the following:

• Raid Commercial Flying Insect Killer

• Raid Indoor Fogger Formula IV

• Raid Flea Killer Plus

• Black Flag Flying Insect Killer

• Ritter’s flea & Tick Spray

• Ortho Tomato & Vegetable Insect Killer

• Bonide Mosquito Insect Spray

• Terro Insect Killer

• Terro Carpenter Ant and Termite Killer

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