Zeroing in on the Causes of Autism

By Brita Belli

Autism research is finally turning its focus to the impact of environmental toxins and finding that exposures to a number of common chemicals—particularly during pregnancy—plays a major role.

Officially, the number of kids with autism in the U.S. is now one in 88, according to the latest numbers from the Centers for Disease Control and Prevention.

But more recent research suggests that when universal screening for autism—a disorder characterized by inhibited social functioning and repetitive behavior—is done, that incidence may be much higher.

And last year, the California Autism Twins Study, which assessed 192 twin pairs born between 1984 and 2004, found that heritability, or genetics, accounted for 38 percent of cases of Autism Spectrum Disorder, while “a shared twin environmental component” accounted for 58 percent of cases.

The idea that toxins—including heavy metals like mercury, pesticides, flame retardants, and chemicals in plastic—along with certain drugs approved during pregnancy and childbirth are directly contributing to these rising autism rates (along with, it should be noted, a host of childhood disorders and diseases on the rise), is the subject of my just-released book The Autism Puzzle: Connecting the Dots Between Environmental Toxins and Rising Autism Rates. In it, I take a close look at the role played by mercury and heavy metals, not in vaccines but in fish and in urban environments.

A 2006 study in Texas, for instance, found that for every 1,000 pounds of environmentally released mercury, there was a 61 percent increase in the rate of autism. Families living in urban environments are particularly vulnerable to toxic assaults—from outdated buildings with peeling lead paint, which is known to cause neurological damage; to cockroach treatments such as the now banned chlorpyrifos, which has been tied to pervasive developmental disorder (including autism) in children exposed in utero; to air pollution.

Often, families living in these conditions are not as able to recognize the signs of autism, and they are more likely to receive a delayed diagnosis or mistaken diagnosis. One study found that among children on Medicaid, those who had been on the program for more than a year were 3.4 times as likely to receive a diagnosis other than autism versus those who had been on Medicaid for less than a year.

At the same time, many of the chemical exposures that seem to act with genetic susceptibility to give rise to autism are nearly ubiquitous across the developed world. Our lax chemical regulations in the U.S., which depend on the threadbare protections of the 1976 Toxic Substances Control Act (TSCA), have exempted some 61,000 chemicals from testing for environmental or human health effects.

That means, for instance, that even when the chemical Bisphenol A (BPA) is declared by the Food and Drug Administration to be of concern for its “potential effects…on the brain, behavior, and prostate gland of fetuses, infants and children,” the agency is still unable to regulate it because it is exempted under TSCA. Both BPA—which lines most soup cans and is present on cash register receipts, and phthalates—industrial compounds that soften plastic and are found in everything from flooring to bath toys to nail polish—have been tied to autism and autism-like behaviors.

While there are steps parents can take to minimize their exposure to chemicals, from buying organic fruits and vegetables to avoiding plastic food storage containers and making their own nontoxic cleaners, it is impossible for any parent to completely steer clear of potentially harmful exposures that can come from furniture, electronics, clothing, cosmetics, or school gymnasiums, to name but a few.

The more research that unfolds connecting autism to chemical exposures, the more it becomes clear that our outdated chemical policy is posing a direct harm to the nation’s children.

Faced with similar concerns, the European Union passed the Registration, Evaluation, Authorisation and Restriction of Chemical substances (REACH) legislation in 2007, which will require all chemical manufacturers to prove the safety of their products and to replace dangerous chemicals with safer alternatives. A similar movement is at work in the U.S. with the Safe Chemicals Act, but thus far has failed to gain political momentum.

With Autism Awareness Month just concluded (April), and a host of childhood sensitivities and disorders on the rise, the time is ripe to push for chemical regulation that truly protects our most vulnerable citizens.


Brita Belli is the editor of E – The Environmental Magazine and the author of The Autism Puzzle: Connecting the Dots Between Environmental Toxins and Rising Autism Rates. She blogs at

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