You Are Here: Home » Blog » General » Pyrethroids: More Damning Evidence Emerges

Pyrethroids: More Damning Evidence Emerges

It’s been almost exactly a year since a Center for Public Integrity report revealed that pyrethrins and pyrethroids were responsible for more than 26,000 human poisonings — making these compounds responsible for 26 percent of all major and moderate human incidents involving pesticides in the United States in 2007.

In the past two weeks, reports coming out of the University of California Berkeley have caused even more alarm — particularly about pyrethroids, which are the synthetic chemical cousin to pyrethrins. The pyrethroids began to dominate the home pesticide market about a decade ago when the EPA and Health Canada removed Dursban and diazinon due to acute toxicity issues. Pyrethrins are derived from chrysanthemums and were not named as a problem in the UC Berkeley report.

“The alarming rise of pesticide-related incidents attributed to pyrethrin and pyrethroid affiliated products is a serious concern for the millions of households that use them,” said Center Executive Director Bill Buzenberg. “The Center for Public Integrity uncovered this public safety issue through more than a dozen Freedom of Information Act requests and crunching the data. This should be basic public information if the EPA were doing its job.”

As a result, the EPA is currently evaluating the health impacts of both pyrethrins and pyrethroids, and certainly the study released in mid July of 2009, led by UC Berkeley toxicologist Donald Weston, will add more fuel to the pyrethroid fire. Weston’s data showed enough pyrethroid runoff in California’s American River to kill tiny shrimp that are a significant part of the waterway’s food chain.

“We were just amazed by this data,” Weston told the Sacramento Bee. “The American River is not supposed to be toxic. I think it reflects the fact that the river’s going through 30 miles of heavy urbanization.”

Numerous fish species are in decline in the river, which is a major part of the Sacramento-San Joaquin Delta ecosystem that supplies water for 23 million Californians.

The Berkeley report would suggest that irresponsible use of the pesticides may be a major part of the problem. The area’s sewage treatment plant — which dumps treated water back into the American River — was determined to be the primary source of the pyrethroid contamination.

Homeowners may also be dumping unused pesticides into sink drains, or allowing pet shampoos containing pyrethroids (that kill fleas, lice and ticks) to wash from driveways into storm drains.

Stan Dean, chief of policy and planning at the Sacramento Regional County Sanitation District, told the local newspaper that a public education program could go a long way.

“Ultimately,” he said, “you might need to have more controls on consumer products that have pyrethroids in them.”

The naturally occurring pyrethrins, used in commonly available household products to control insects in the home, on pets, and on people, are allowed in organic gardening protocols. Their synthetic counterparts, pyrethroids — which are not allowed in organic gardening regulations — have similar properties to pyrethrins, and were created as safer alternatives to an earlier class of pesticides (organophosphates such as Dursban and diazinon), originally derived from nerve gas. Manufacturers’ use of pyrethroids has grown widely to include thousands of household products, ranging from bug repellants, anti-lice shampoos, pet shampoos, and carpet cleaners.

While pyrethroids are still generally believed to be less toxic than organophosphates, the number of reported human health problems, including severe reactions and even deaths attributed to pesticides containing pyrethrins and pyrethroids, increased from 261 in 1998 to 1,030 in 2007, nearly a 300 percent increase. Pyrethrins and pyrethroids accounted for more incidents than any other class of pesticide over the last five years. EPA data shows at least 50 deaths attributed to this supposedly safer class of pesticides since 1992.

The EPA does not require product warning labels cautioning consumers with allergies of the dangers associated with pyrethrins and pyrethroids products. However, the Food and Drug Administration does require warning labels on shampoos that contain pyrethrins and pyrethroids.


This report includes contributions from the Center for Public Integrity, a nonprofit, nonpartisan independent Washington, D.C.-based organization that does investigative reporting and research on significant public issues.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1024
  • Ahmad Mahdavi

    During my work in home pest control in Canada I observed many cases of human toxicity with permethrin. I wonder why in a country like Canada pest control companies are allowed to use so much uncontroled pyrethroids everywhere in cities, now that cosmetic pesticides are banned in Ontario cities authorities in health Canada should retkink about using so much pyrethroids in home pest control. You can find residues everywhere in Canada.

  • Pingback: synthetic pyrethroids

Scroll to top