!UT Health Science Center Autism Study

[Guest guest]

This is the second study done by Dr Palmer on autism

rates and emission levels. The first study was published in 2006 and

also showed a correlation between levels of emissions and

autism/special education rates in Texas.

The full text of the second study isn't yet available, but scroll

down past the description of the current research to see a summary &

link to the first study.

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Study links autism risk to distance from power plants, other mercury-

releasing sources

SAN ANTONIO (April 24, 2008)—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

, 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. "

Multiple avenues of exposure

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. "

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. "

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.

Citation

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

http://www.ncbi.nlm.nih.gov/pubmed/18353703

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This is Dr Palmer's first study:

Environmental mercury release, special education rates, and autism

disorder: an ecological study of Texas

(link to full text of article:

http://familymed.uthscsa.edu/news/PalmerAutismArticle.pdf )

Palmer RF - Blanchard S - Stein Z - Mandell D - C

The association between environmentally released mercury, special

education and autism rates in Texas was investigated using data from

the Texas Education Department and the United States Environmental

Protection Agency.

A Poisson regression analysis adjusted for school district population

size, economic and demographic factors was used. There was a

significant increase in the rates of special education students and

autism rates associated with increases in environmentally released

mercury.

On average, for each 1,000 lb of environmentally released mercury,

there was a 43% increase in the rate of special education services

and a 61% increase in the rate of autism. The association between

environmentally released mercury and special education rates were

fully mediated by increased autism rates.

This ecological study suggests the need for further research

regarding the association between environmentally released mercury

and developmental disorders such as autism. These results have

implications for policy planning and cost analysis.

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