EWG report on autism
Scientists have identified a signature metabolic impairment or "biomarker" in autistic children that strongly suggests that these children would be susceptible to the harmful effects of mercury and other toxic chemical exposures .
This impairment manifests as a severe imbalance in the ratio of active to inactive glutathione, the body's most important tool for detoxifying and excreting metals. Glutathione works as an antioxidant, keeping in check the potentially destructive process of oxidative stress caused both by normal metabolism and environmental contaminants. Autistic children showed a significant impairment in every one of five measurements of the body's ability to maintain a healthy glutathione defense.
These findings raise serious concerns about children's overall exposure to environmental contaminants. Mercury is of particular concern, however, because of its proven toxicity to the developing brain and nervous system, and documented high exposures from a variety of sources.
One of every six pregnancies is exposed to methyl mercury above EPA's safe level from maternal consumption of contaminated seafood (CDC 2002, Mahaffey 2004). Thimerosal, a preservative in vaccines that is 49 percent ethyl mercury, was a major source of mercury exposure from 1988 through 2002 when it was removed from childhood immunizations at the urging of the Public Health Service and the American Academy of Pediatrics. Elemental mercury from dental amalgams is another potentially important source, but its contribution to overall mercury exposure is less well studied.
The incidence of autism increased 10-fold from 6 in 10,000 in the 1980s (Blaxill 2004), to about 60 in 10,000 today (Autism Alarm, PDF file). These new findings significantly strengthen the possibility that mercury could cause or contribute to autism and other neurodevelopmental disorders by identifying a metabolic imbalance common to nearly all autistic children that would make these children poorly equipped to mount a defense against a number of neurotoxic compounds, including mercury.
These findings could have major implications for public health protections from toxic chemicals in the environment. They identify a subgroup of people at increased risk of harm, and provide important new evidence that policies designed to protect the average person, or even the average child, from chemical exposure, are insufficient to fully protect the public health. Environmental and health officials must evaluate the adequacy of current laws and policies to protect individuals with a heightened sensitivity to chemical exposure.
Finally, these findings raise serious concerns about the studies that have allegedly proven the safety of mercury in vaccines. The epidemiologic studies used to dismiss a causal relationship between autism and thimerosal have assumed that all children have the same resistance to chemical exposure. To properly investigate the potential harm from mercury-containing shots researchers would have to compare autism rates in children with the same type of vulnerability.