From Autism Speaks
February 18, 2014
Researchers link more pollutants to disorders of brain development; call for global prevention strategy to control use.
A new report implicates a growing number of industrial chemicals as contributing to autism and other disorders of brain development. The authors call for a global strategy to reduce exposure.
The report appears online in Lancet Neurology. The authors are Harvard environmental epidemiologist Philippe Grandjean and Mount Sinai Medical School pediatrician and epidemiologist Philip Landrigan.
The new report summarizes evidence from published studies on industrial chemicals and brain toxicity and updates the review that the authors conducted in 2006.
Five Known Threats to Brain Development
Their 2006 review identified five widely used industrial chemicals as "developmental neurotoxicants." Such chemicals can contribute to developmental brain disorders such as autism. The five: lead, methylmercury, polychlorinated biphenyls, arsenic and toluene.
In addition, the 2006 report identified more than 200 industrial chemicals that cause brain damage in adults. The authors warned that many of these might likewise cause developmental brain disorders if exposure occurred during pregnancy or early infancy.
Six More Chemicals on the Danger List
The new report adds six chemicals to the list of developmental neurotoxicants. They are high doses of manganese or fluoride, the pesticides chlorpyrifos and DDT, the solvent tetrachloroethylene and polybrominated diphenyl ethers. Polybrominated diphenyl ethers are flame retardants applied to furniture.
Manganese and fluoride become toxic only at unnaturally high levels. The doses in vitamins and dental-hygiene products are safe.
While exposure to some of these chemicals is common in North America, the highest exposures tend to occur in developing nations, notes Alycia Halladay, Autism Speaks senior director for environmental and clinical sciences. “Most exposures are hard for individuals to control themselves.”
Dr. Halladay adds, “One way to prevent exposure is through regulation of toxins. This was the case with the elimination of lead from gasoline and paint, as well as the reduction of some air pollutants after the passage of the Clean Air Act.”
Meanwhile, Dr. Halladay agrees with the authors’ call for more research on the hundreds of toxic industrial chemicals now polluting the environment.
Many other neurotoxicants are likely contributing to a "silent pandemic" of developmental brain disorders, Drs. Grandjean and Landrigan write. As evidence, they cite studies linking autism risk to prenatal exposure to high levels of air pollution. (Click here for the full text of one of these studies, funded in part by Autism Speaks.)
Autism Speaks Funds Further Research
Autism Speaks has funded a number of studies on autism risk and air pollution. In addition, it is currently supporting several studies collecting information on autism risk and exposures to other types of toxic chemicals.
To further speed discoveries, Autism Speaks is also funding the development of the Early Life Exposure Assessment Tool (ELEAT). Designed for autism research, this allows investigators to combine the results of multiple studies on early environmental exposures. By increasing sample sizes, this will boost scientists’ ability to uncover toxic effects.
Learn more about Autism Speaks Environmental Factors in Autism Initiative here. For a full list of Autism Speaks studies on environmental risk factors for autism, click here.