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Public Radio's Environmental News Magazine (follow us on Google News)

Mercury and Autism

Air Date: Week of

Coal-fired power plants will have to start trading mercury emissions in an effort to cut down on the heavy metal that's been known to bioaccumulate in fish and people. Now there's evidence that makes this goal all the more urgent. Researchers at the University of Texas found a link between the mercury that comes out of smokestacks, and the rate of autism in Texas schools. Host Steve Curwood talks with one of the study's authors, Dr. Claudia Miller.


CURWOOD: Scientific studies have found atypical amounts of the heavy metal mercury in children with autism, a spectrum of neurological disorders associated with communication and behavior problems. But, it has been unclear how much mercury might be involved, until now. Researchers at the University of Texas at San Antonio are reporting that autism rates in school children rise by 17 percent with every thousand pounds of mercury released from smokestacks. These findings only show an association between mercury and autism. They do not prove that mercury causes autism. With me now to discuss these findings is Dr. Claudia Miller. She's a professor at the University of Texas Health Science Center in San Antonio and co-author of the study. Dr. Miller, hello.

MILLER: Hello.

CURWOOD: How did you do this study?

MILLER: What we did is we obtained data that's publicly available from the Environmental Protection Agency regarding mercury release in 254 Texas counties, and correlated that with information from over a thousand school districts within Texas and looking specifically at the rates of autism in those counties and the rates of special education students in those counties. This was done during 2000, 2001. There was a higher rate, interestingly, in metropolitan areas compared to rural areas, almost a four-fold difference. And, also a higher rate in suburban areas than in rural areas almost a two and a half fold difference.

CURWOOD: Of the autism that was found?

MILLER: Correct.

CURWOOD: Now, how does this chain of events unfold from the point that mercury comes out of the smokestack of a power plant to the point when a child might develop behavioral problems?

MILLER: The mercury that's emitted with the coal burning is associated with particles and those particles that go into the atmosphere, smoke particles, will deposit into bodies of water, rivers, streams, lakes. Fish will take it up after micro-organisms have converted this mercury to a form that is what we call organic mercury which is easily taken up into the body and into the central nervous system. And, as you go up the food chain and finally to man, the levels of mercury increase proportionally.

CURWOOD: So, what might be the mechanisms that this mercury acts on a developing fetus or child. What at these low levels, what might it do?

MILLER: The concern is that mercury would interfere with the connections that neurons form between each other, the synapses as development is occurring. There's a time in development when neurons are pruned, like you prune a bush that are pruned back. And, this may not happen normally in children with autism. It's one of the theories that's been proposed.

CURWOOD: And, by the way, how close is too close to a mercury generating power plant?

MILLER: That's a very good question. Really, when you think about the emissions, they are carried in the air and the fallout of the larger particles would occur sooner than the smaller ones. So, in fact, people living within closer proximity would potentially have more exposure, but we really don't know completely because sometimes these things are carried and then wind currents will drop them down at unpredictable places. So, this is not as simple either as identifying lead paint in a home. In a home, you can go in and remove that paint and we know for sure that that can make a difference in the child's blood lead levels and in their development. And, that's a public health measure that was implemented as a result of multiple studies, actually over decades. I think we shouldn't wait that long.

CURWOOD: Dr. Claudia Miller is a professor at the University of Texas Health Science Center in San Antonio. Dr. Miller, thanks for taking this time with me, today.

MILLER: Thank you.

CURWOOD: Just ahead: The magic of the soporific roar of the ocean, courtesy of modern technology. Stay tuned to Living on Earth.

ANNOUNCER: Support for NPR comes from NPR stations, and Aveda, working to save threatened and endangered species by responsibly sourcing plant ingredients for hair, skin and body care, aveda.com; the Kresge Foundation, building the capacity of nonprofit organizations through challenge grants since 1924. On the web at k-r-e-s-g-e.org; the Annenberg Fund for excellence in communications and education; and the W.K. Kellogg Foundation, from vision to innovative impact, 75 years of philanthropy. This is NPR, National Public Radio.

[MUSIC: Hound Dog Taylor and the Houserockers "Give Me Back My Wig" Martin Scorcese Presents the Blues--A Musical Journey (Universal Music Ent.) 2003]



University of Texas News Release on Study


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