Autism and environmental toxins

A recent study by researchers at the University of California Medical Investigation of Neurodevelopmental Disorders (MIND) Institute has linked soaring rates of autism and autism spectrum disorders with fetal and infant exposure to pesticides and household chemicals.

“It’s time to start looking for the environmental culprits responsible for the remarkable increase in the rate of autism in California,” MIND Institute researcher Irva Hertz-Picciotto, an internationally respected autism researcher and professor of environmental and occupational health and epidemiology.

Hertz-Picciotto said that many researchers, state officials, and advocacy organizations have viewed the rise in the incidence of autism in California with skepticism. Some claim that the increase could be due to the migration to California of families with autistic children, earlier diagnosis because of increased awareness, and also the inclusion of children with milder forms of autism in the counting.

The study published in the January 2009 issue of the journal Epidemiology¹, found that the nearly eight-fold increase in the number children born in California with autism since 1990 could not be explained by either changes in how the condition was diagnosed or counted.

Results from the study also suggest that research should shift from genetics to a host of chemicals and infectious microbes in the environment that are likely at the root of the changes occurring in the neurodevelopment of California’s children.

Hertz-Picciotto and her co-author, Lora Delwiche of the UC Davis Department of Public Health Sciences, initiated the study to address these ideas, analyzing data collected by the California Department of Developmental Services from 1990 to 2006, as well as the U.S. Census Bureau and California Department of Public Health Office of Vital Records, which compiles and maintains birth statistics.

Hertz-Picciotto and her colleagues at the MIND Institute are currently conducting two large studies aimed at discovering the causes of autism. Hertz-Picciotto is the principal investigator on Childhood Autism Risk from Genetics and the Environment (CHARGE) and Markers of Autism Risk in Babies-Learning Early Signs (MARBLES).

CHARGE is the largest epidemiologic study of reliably confirmed cases of autism to date and the first major investigation of environmental factors and gene-environment interactions in the disorder.

MARBLES is a prospective investigation that follows women who already have had one child with autism, beginning early in or even before a subsequent pregnancy, to search for early markers that predict autism in the younger sibling.

“We’re looking at the possible effects of metals, pesticides and infectious agents on neurodevelopment,” Hertz-Picciotto said. “If we’re going to stop the rise in autism in California, we need to keep these studies going and expand them to the extent possible.”

Sources:

1. The Rise in Autism and the Role of Age at Diagnosis Hertz-Picciotto, Irva; Delwiche, Lora  Epidemiology. 20(1):84-90, January 2009.

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