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Rainfall, Autism May Be Linked

Children Living in High-Precipitation Areas More Likely to Have Autism, Study Shows

Precipitation-Autism Link: Study Interpretations

The results do raise the possibility that an environmental trigger for autism may be linked to precipitation, perhaps affecting children who are genetically vulnerable, the researchers say.

"It could be the rain itself," Nicholson says. For instance, chemicals in the upper atmosphere may be transported to the surface by the rain, the researchers speculate.

Or, as Waldman suggests, the amount of time children spend indoors when they live in a heavy rainfall area might increase their exposure to potentially harmful chemicals, such as those from cleaning products. Being indoors could decrease their sunshine exposure, thus reducing vitamin D levels.

Precipitation-Autism Link: Caveats

The observation about precipitation and autism rates may not lead to any insights at all on the causes of the disorder, writes Noel Weiss, MD, DrPh, a professor of epidemiology at the University of Washington, Seattle, in an editorial accompanying the study.

"These results are really [meant] to alert other investigators to the hypothesis," he tells WebMD.

The findings, he adds, should not be taken as a reason to move to a drier climate or a reason to ban television viewing.

Take-Home Advice

The results are not definitive evidence of a precipitation-autism link, as Waldman, Nicholson, and their colleagues acknowledge in the report.

"But the results are consistent with the hypothesis, and, therefore, further research focused on establishing whether such a trigger exists and on identifying it is warranted," they conclude.


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