A class of insecticides known as pyrethroids used inside the home is increasingly found in the human body, a team of researchers from UC Davis has discovered, raising alarm over the long-term effects of the chemicals on people.
The study also found that children in particular are still widely exposed to an insecticide that was banned for household use over a decade ago—chlorpyrifos.
“The thing to be wary of is that these products, when used inside the home, last a very long time," said Kelly Trunnelle, lead researcher of the UC Davis study.
The indoor use of pyrethroids has grown rapidly since 2001 when chlorpyrifos was phased out after it was discovered to damage neurological health.
As Shruti Ravindran at The Verge reports:
Across cities and suburbs, pyrethroids and pyrethrins are sprinkled over lawns, soaped onto pets, sprayed on offending vermin, and occasionally applied to our own persons in the form of lice-killing shampoos or mosquito repellents. They're also used in landscaping, in fumigating drives against mosquitoes, and in agricultural crops and nurseries. In 2009, the US Environmental Protection Agency (EPA) found pyrethroids and pyrethrins in more than 3,500 registered commercial products.
Over 60 percent of people examined in the study tested positive for having pyrethroids in their system.
Very few studies have examined the long-term effects of pyrethroids on humans in home-based exposure, although the research is growing. As the Sacramento Bee reports:
To date, scant research has been done on pyrethroids, which are commonly used for farming as well as in household products... However, studies on the chemical are increasing, as are concerns about its possible health effects such as endocrine disruption and autism. A 2008 study found that the pyrethroid esfenvalerate delayed the onset of puberty in laboratory rats. A UC Davis study that same year found mothers of autistic children had shampooed their pets with antiflea and antitick shampoos during pregnancy. In that study, the mothers reported they did so twice as much as mothers that gave birth to typically developing children.
“It’s well-documented that pyrethroids and chlorpyrifos are more persistent in the indoor environment,” Trunnelle said. “Unfortunately, this information may not be widely understood by the general public.”
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