How Environmental Toxins May Contribute to Autism Spectrum Disorder

by Brita Belli

When the results of an autism study were published in the journal Pediatrics in October 2009, the figures were shocking—one in every 91 U.S. children was reported to have autism. That was up from one in 500 a decade ago, with boys four times as likely to acquire the disorder.

Behaviors of autism include: failure to respond to stimuli or make eye contact; speech delays; compulsive behavior like head-shaking; stacking objects or intense repetition of daily activities; and extreme noise sensitivity.

For years, research into the causes of autism has revolved around genetics. Even as the rate of autism among the nation’s children continues to rise at an astonishing 10 to 17 percent a year, research has been slow to shift its focus to other factors—namely, environmental toxins.

The Chemical Connection

New autism research is making the case that environmental toxins such as mercury, lead, polychlorinated biphenyls (PCBs), flame retardants and pharmaceutical drugs—including antidepressants in utero or antibiotics in infancy—may be aggravating a pre-existing genetic condition.

Yet James Adams, head of the Autism/Asperger’s Research Program at Arizona State University, remarks that, “There is still extremely little money out there for looking into environmental issues.”

Adams’ own research has discovered a correlation between heavy metal exposure and autism severity. In one study, Dimercaptosuccinic acid (DMSA), a medication used to treat lead poisoning, was administered to children with autism. The researchers found that children with autism “dumped three times as much mercury as typical children,” reports Adams, suggesting that their bodies could not properly excrete the toxin. In another study, the baby teeth of children with autism were found to contain twice the mercury as those of typical children.

Adams’ findings have also uncovered one common thread in the medical history of children with autism: heavy use of oral antibiotics in infancy. He explains that antibiotics disrupt the gut’s good flora, further diminishing the child’s ability to excrete toxins. Such treatments are primarily used for recurring ear infections, but as Dr. Jerry Kartzinel reports in his book, Healing and Preventing Autism (co-written with celebrity autism treatment advocate Jenny McCarthy), those frequent ear infections are, “the most common marker for immune system dysfunction... in babies and very young children.”

A New Approach

A growing number of doctors like Kartzinel and researchers like Adams are subscribing to the protocols set out by Defeat Autism Now! (DAN), a project of the nonprofit Autism Research Institute, which supports a biomedical basis for autism and its treatment. DAN practitioners, according to the group’s description, “do not regard psychotropic drugs as the best or only means of treating autistic patients.” Instead, they look for triggers that may aggravate a pre-existing genetic condition. These include everything from vaccines to environmental toxins, like mercury, in fish, arsenic in drinking water and lead in air pollution; overuse of antibiotics and over-the-counter medicines in early infancy; and a diet heavy in wheat and dairy that contributes to gut inflammation.

This holistic view of autism’s causes also extends to the potential range of treatments. These may include chelation therapy (removing heavy metals), gluten- and casein-free diets (removing wheat and dairy), administering supplements with omega-3 fatty acids and/or hyperbaric oxygen therapy (in which oxygen is administered in a pressurized chamber).

“The presumption,” advises Richard Lathe, a molecular biologist and author of Autism, Brain, and Environment, “is that environmental toxicity has increased enough that, combined with childhood vaccines, [industrial] production and fish consumption, it has led to an increase in total exposure to heavy metals.”

Consequently, these concerned researchers are pointing out clear steps that parents can take to minimize their own and their children’s toxic exposures, starting by taking precautions during pregnancy, minimizing exposure to mercury by avoiding fish like shark and swordfish and limiting consumption of albacore tuna. Pregnant women, counsels Lathe, should also be sure to take the proper prenatal vitamins, such as calcium, so that the fetus is not drawing minerals from the mother’s bones, where heavy metals are stored.

“The body locks heavy metals away in bone and fat,” explains Lathe. “During pregnancy, that stuff is recycled [in supplying nourishment] to the child.”

It’s also important to avoid exposures to toxic chemicals via cleaning products, both during pregnancy and after birth. Homemade substitutes, using ingredients like distilled white vinegar and baking soda, are safe (and cheap) alternatives. Other chemical culprits? Plastic containers and bath toys can leech chemicals when heated, cleaned or used for teething. Car seats and crib mattresses made with flame retardants, as well as toys with lead paint, carry toxins.

A 2005 study from the nonprofit watchdog Environmental Working Group found an average of 200 industrial chemicals and pollutants in umbilical cord blood samples from 10 babies born in U.S. hospitals around the country. Of these, the report said, “180 cause cancer in humans and animals, 217 are toxic to the brain and nervous system and 208 cause birth defects... in animal tests.”

For children who may have an underlying genetic predisposition to autism, the chemical overload starts early. Increasing it through allergy-triggering diets, an overload of antibiotics and/or mercury-containing vaccines could have dangerous, long-lasting consequences. Informed parents know to take precautions early and often.

Resources: Autism Research Institute at DefeatAutismNow.com; Environmental Working Group at ewg.org; Pediatrics published study at http://pediatrics.aappublications.org/cgi/content/abstract/peds.2009-1522v1.

Brita Belli is the editor of E – The Environmental Magazine.