Fw: Autism Risk Linked To Distance From Power Plants, Other Mercury-Releasing Sources

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Autism Risk Linked To Distance From Power Plants, Other Mercury-Releasing

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ScienceDaily (Apr. 25, 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 , 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.

“This is not a definitive study, but just one more that furthers the

association between environmental mercury and autism,†said lead author

F. Palmer, Ph.D., associate professor of family and community

medicine at the UT Health Science Center San . The article is in

the journal Health & Place.

Dr. Palmer, Blanchard, Ph.D., of Our Lady of the Lake

University in San and 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.

“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.â€

The study should encourage further investigations 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.â€

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.

Study highlights

Mercury-release data examined were from 39 coal-fired power plants and 56

industrial facilities in Texas.Autism rates examined were from 1,040 Texas

school districts.For every 1,000 pounds of mercury released by all industrial

sources in Texas into the environment in 1998, there was a corresponding

2.6 percent increase in autism rates in the Texas school districts in

2002.For every 1,000 pounds of mercury released by Texas power plants

in 1998, there was a corresponding 3.7 percent increase in autism rates

in Texas school districts in 2002.Autism prevalence diminished 1 percent to 2

percent for every 10 miles from the source.Mercury exposure through fish

consumption is well documented,

but very little is known about exposure routes through air and ground

water.There is evidence that children and other developing organisms are more

susceptible to neurobiological effects of mercury.

Implications

“We need to be concerned about global mercury emissions since a

substantial proportion of mercury releases are spread around the world

by long-range air and ocean currents,†Dr. Palmer said. “Steps for

controlling and eliminating mercury pollution on a worldwide basis may

be advantageous. This entails greener, non-mercury-polluting

technologies.â€

The U.S. Environmental Protection Agency (EPA) estimated

environmental mercury releases at 158 million tons annually nationwide

in the late 1990s, the time period studied by the Texas team. Most

exposures were said to come from coal-fired utility plants (33 percent

of exposures), municipal/medical waste incinerators (29 percent) and

commercial/industrial boilers (18 percent). Cement plants also release

mercury.

With the enactment of clean air legislation and other measures, mercury

deposition into the environment is decreasing slightly.

Limitations

Dr. Palmer and his colleagues pointed out the study did not reflect

the true community prevalence rates of autism because children younger

than school age are not counted in the Texas Education Agency data

system. The 1:500 autism rates in the study are lower than the 1:150

autism rates in recent reports of the U.S. Centers for Disease Control

and Prevention.

Furthermore, the authors note that distance was not calculated from

individual homes to the pollution source but from central points in

school districts that varied widely in area.

Data sources

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.

Journal reference: 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 above story is reprinted (with editorial adaptations by ScienceDaily

staff) from materials provided by University of Texas Health Science Center at

San .