Raymond F. Palmer, Ph.D., associate professor of family and community medicine, was lead author on the study.
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SAN ANTONIO, Texas (April 24, 2008) — How do mercury emissions affect pregnant mothers, the unborn and toddlers? Do the level of emissions impact autism rates? Does it matter whether a mercury-emitting source is 10 miles away from families versus 20 miles? Is the risk of autism greater for children who live closer to the pollution source?

A newly published study* of Texas school district data and industrial mercury-release data, conducted by researchers at The University of Texas Health Science Center at San Antonio, indeed shows a statistically significant link between pounds of industrial release of mercury and increased autism rates. It also shows — for the first time in scientific literature — a statistically significant association between autism risk and distance from the mercury source.

Additional information: Study highlights Implications Limitations

“This is not a definitive study, but just one more that furthers the association between environmental mercury and autism,” said lead author Raymond F. Palmer, Ph.D., associate professor of family and community medicine at the UT Health Science Center San Antonio.

Dr. Palmer, Stephen Blanchard, Ph.D., of Our Lady of the Lake University in San Antonio and Robert Wood of the UT Health Science Center found that community autism prevalence is reduced by 1 percent to 2 percent with each 10 miles of distance from the pollution source.



Study does not address individuals’ risk of autism
“This study was not designed to understand which individuals in the population are at risk due to mercury exposure,” Dr. Palmer said. “However, it does suggest generally that there is greater autism risk closer to the polluting source.”

Study opens door to further investigation
The study should encourage more protocols designed to determine the multiple routes of mercury exposure. “The effects of persistent, low-dose exposure to mercury pollution, in addition to fish consumption, deserve attention,” Dr. Palmer said. “Ultimately, we will want to know who in the general population is at greatest risk based on genetic susceptibilities such as subtle deficits in the ability to detoxify heavy metals.”

The new study findings are consistent with a host of other studies that confirm higher amounts of mercury in plants, animals and humans the closer they are to the pollution source. The price on children may be the highest.

“We suspect low-dose exposures to various environmental toxicants, including mercury, that occur during critical windows of neural development among genetically susceptible children may increase the risk for developmental disorders such as autism,” the authors wrote.

Sources of data used in the study
Data for environmentally released mercury were from the "United States Environmental Protection Agency Toxics Release Inventory." Data for releases by coal-fired power plants came from the same inventory and from the Texas Commission for Environmental Quality. Data for school district autism came from the Texas Education Agency.

* Palmer, R.F., et al., "Proximity to point sources of environmental mercury release as a predictor of autism prevalence." Health & Place (2008), doi:10.1016/j.healthplace.2008.02.001.

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The University of Texas Health Science Center at San Antonio is the leading research institution in South Texas and one of the major health sciences universities in the world. With an operating budget of $576 million, the Health Science Center is the chief catalyst for the $15.3 billion biosciences and health care sector in San Antonio’s economy. The Health Science Center has had an estimated $35 billion impact on the region since inception and has expanded to six campuses in San Antonio, Laredo, Harlingen and Edinburg. More than 23,000 graduates (physicians, dentists, nurses, scientists and allied health professionals) serve in their fields, including many in Texas. Health Science Center faculty are international leaders in cancer, cardiovascular disease, diabetes, aging, stroke prevention, kidney disease, orthopaedics, research imaging, transplant surgery, psychiatry and clinical neurosciences, pain management, genetics, nursing, allied health, dentistry and many other fields. For more information, visit www.uthscsa.edu.