Common Chemicals May Have Autism Link

May 15, 2008 — -- For parents of children with autism, the knowledge that some unknown chemical caused their child's developmental disorder can weigh heavily on their minds.

Researchers think that a complex combination of genetic and environmental factors contributes to autism, but they don't know what all those environmental factors are.

A preliminary study out of California might have uncovered at least one chemical worthy of investigation: pyrenthrin, a type of pesticide found in common products, from pet shampoos to household bug killers.

Mothers of more than 500 young children (some autistic, some not) participated in the study, reporting long lists of products they remembered using from a few months before conception until their child turned 1.

Mothers of the 138 children with autism were twice as likely to report using pet shampoos and other household products containing pyrenthrins than other mothers.

But while the findings in the study seem strong, lead author Irva Hertz-Picciotto, professor in the Department of Public Health Sciences at University of California, Davis, and other autism experts agree that there is a lot of work left to make sure pyrenthrin isn't a red herring.

Asking a busy mother about all the products she used in pregnancy can be tricky, but it becomes especially tricky if she had no reason to remember what she used.

"As soon as they know the child's OK, they're going to forget anything they might have done," said Dr. Ernest Krug, director of the Center for Human Development at William Beaumont Hospital, in Berkeley, Mich. "It's interesting, but then you have to go to the next step."

Krug says a good way to do a second study would be to ask the mothers to keep track of the products they use in the beginning of their pregnancies -- before they know if a child will be autistic.

However, narrowing down pyrenthrin from the slew of other chemicals mothers and infants encounter still would only be part of the job.