Connecting PCBs and Autism

April 25, 2007

As autism rates have soared, parents, researchers and doctors have struggled to find its cause or causes. Now scientists at University of California San Francisco and UC Davis have found that exposing rats to PCBs as a fetus and while nursing can cause symptoms of autism.

And we're not talking about rodents given wildly high doses of the banned-but-prevalent industrial chemicals. In this story by the L.A. Times' Marla Cone, the levels are described as low, and "brain development is skewed when animals are exposed to amounts of PCBs in the same range as some highly exposed people."

From Cone:
Many scientists say that an array of chemicals in the environment are scrambling brain development and could play a role in children's learning disorders.

The new study adds to the evidence by showing that PCBs, polychlorinated biphenyls, disrupt the auditory cortex, a part of the brain that is impaired in autistic children.

One reason this caught my interest was the number of emails I received after stories I'd written about the proposed then approved ban on PBDEs, a family of flame retardant chemicals that are similar in structure to PCBs. Readers wondered if researchers had looked at PBDE levels in kids with autism, and the answer is no. Little investigation has been done in PBDE levels in kids at all, and I also don't think that the scientists have looked for autistic effects in rats exposed to the chemicals.

The PCB work builds on mounting evidence of risks posed by industrial chemicals, which was compiled in this November 2006 article in The Lancet.

In summary (from a Harvard press release):

The researchers found that 202 industrial chemicals have the capacity to damage the human brain, and they conclude that chemical pollution may have harmed the brains of millions of children worldwide. The authors conclude further that the toxic effects of industrial chemicals on children have generally been overlooked.

A little more on the PCB study. The scientists involved are accomplished researchers at prominent universities publishing their work in the well-regarded Proceedings of the National Academy of Sciences. (Authors include Michael M. Merzenich of UCSF's W.M. Keck Foundation Center for Integrative Neuroscience, Tal Kenet, who led the research team in Merzenich's lab while a postdoctoral fellow, and Isaac N. Pessah, an autism researcher at the UC Davis M.I.N.D. Institute and director of the university's Center for Children's Environmental Health and Disease Prevention.)

Source: Seattle Post Intelligencer