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Mercury in Air Pollution: A Link to Autism?

More Autism Seen in Texas Counties With Most Mercury Pollution
WebMD Health News

March 18, 2005 - Can mercury in air pollution cause autism? Nobody knows. But a new study suggests it's worth a look.

Mercury is one heck of a toxic substance. A fraction of a teaspoon can render all the fish in a 20-acre lake unsafe to eat.

A recent Institute of Medicine study found no link between the tiny amounts of mercury in childhood vaccines and autism. But the jury is still out on whether prenatal exposure to mercury might affect brain development.

Could environmental exposure to mercury affect autism rates? Raymond F. Palmer, PhD, and colleagues at the University of Texas Health Science Center explored the issue. They looked at EPA figures on industrial mercury release -- most of which comes from coal-fired power plants -- in 254 Texas counties. They compared these figures to autism rates from the counties' 1,184 school districts, taking into account other factors linked to autism.

Mercury Dumping, More Autism

"We found that for every 1,000 pounds of mercury released by industry, there was a 17% increase in autism," Palmer tells WebMD. "This is one of the most highly toxic [nerve-damaging substances] on earth. So when we talk about 50 pounds, 1,000 pounds, 2,000 pounds released into the environment, this is a tremendous amount of potential exposure. But we do not know how these exposures get into the body."

The findings are scheduled to appear in the journal Health & Place.

No Proof Mercury Pollution Causes Autism

Palmer is quick to point out that this kind of study does not prove mercury pollution causes autism.

"We show a significant relationship between mercury release into the environment and autism. But that does not prove causation," Palmer says.

Palmer's team is planning a long-term study to see whether actual fetal mercury exposure can be linked to autism.

"The ultimate goal of this work is to help us think about what we want to let out in the environment," Palmer says. "Is there an acceptable risk for mercury exposure? We don't know. We would like to affect political action, but we need harder data to do that. This study is just a first step."

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