(Beyond Pesticides, November 1, 2013) Insecticides commonly used in homes and schools are associated with behavioral problems in children, according to a recent study by Canadian researchers. The study investigates exposure to pyrethroid pesticides, used in more than 3,500 products, including flea and tick controls, cockroach sprays, and head lice controls. The study, Urinary metabolites of organophosphates and pyrethroid pesticides and behavioral problems in Canadian children, published in the journal Environmental Health Perspectives, raises serious concerns about the impact of pyrethroids, which are increasingly used as a replacement for organophosphates.

This study uses data from the Canadian Health Measures Survey (2007-2009), a nationally representative survey, so researchers are able to apply these findings to the entire population of Canadian children. In a previous study among U.S. children, researchers at the National Health and Nutrition Examination Survey (NHANES) examined the metabolites of pyrethroids in children below the age of six. Similarly, they found pyrethroid insecticides in more than 70 percent of the samples, concluding that children had significantly higher metabolite concentrations than those of adolescents. Together these studies demonstrate that exposure is widespread, with real impacts to human health.

In the recent study, researchers analyzed organophosphate and pyrethroid metabolites in the urine of 770 Canadian children between the ages of 6 and 11. Each parent was also asked three questions about their use of indoor pesticides, pyrethroid pesticides, and outdoor pesticides within the last month. The study found, “significant associations of high scores on emotional symptoms with use of pesticides for pets/head lice, and for any use of pesticides (either indoor, outdoor, or pets/head lice), in the previous month (adjusted OR [odds ratio] = 3.8 [elevated by 3.8 times]; 95% CI: 1.5, 9.5 and adjusted OR = 2.7; 95% CI: 1.5, 5.1, respectively).” The study authors continue, “In addition, indoor use of pesticides in the previous month was significantly associated with elevated scores on conduct problems (adjusted OR = 3.2; 95% CI: 1.0, 10.5).”

Though only 14 percent of parents reported pesticide use in the last month, researchers Youssef Oulhote, M.Eng, PhD., and Maryse Bouchard, PhD., of Université de Montréal, found that 97 percent of children had traces of the pyrethroid metabolite cis-DCCA in their urine, while 91 percent of them had traces of at least one organophosphate metabolite. “This suggests that exposure events are common”¦[and that] although pyrethroids are assumed to degrade quickly by hydrolysis and photolysis, these processes might be considerably slowed indoors, thus leaving pesticides residues to linger and accumulate,” the study says.

The study concludes that with a tenfold increase in urinary levels of cis-DCCA, children are twice as likely to score high on parent-reported behavioral problems, including inattention and hyperactivity. Cis-DCCA and trans-DCCA, the breakdown products of pyrethroids are specifically traced to the pesticides permethrin, cypermethrin, and cyfluthrin.

Pesticide products containing synthetic pyrethroids are often described by pest control operators and community mosquito management bureaus as “safe as chrysanthemum flowers.” While pyrethroids are a synthetic version of an extract from the chrysanthemum plant, they are chemically engineered to be more toxic, take longer to break down, and are often formulated with synergists, increasing potency, and compromising the human body’s ability to detoxify the pesticide.

Pyrethroids are known irritants and can have a high acute toxicity depending on the specific formulation. Pyrethroids have also been connected to multiple symptoms of acute toxicity, asthma, incoordination, tremors, and convulsions. In addition to human health effects pyrethroids are also persistent in the environment and adversely impact non-target organisms. A recent study found that residents of New York City are more highly exposed to organophosphates and pyrethroid pesticides than the average American. Another 2008 survey found pyrethroid contamination in 100 percent of urban streams sampled in California.

Mounting research on the impacts of pesticides to human health present a clear need for least-toxic management of homes, which effectively prevents the infestation of unwanted insects without the use of synthetic chemicals. These techniques include exclusion, sanitation and maintenance practices, as well as mechanical and least-toxic controls (which include boric acid and diatomaceous earth). Based on range of successful pest prevention practices, use of these hazardous chemicals are unnecessary.

For more information, see Beyond Pesticides’ factsheet, Common Pesticide Poison Homes and Children and Pesticides Don’t Mix.

Sources: Environmental Health News, Environmental Health Perspectives

All unattributed positions and opinions in this piece are those of Beyond Pesticides.