Autism, mercury possibly linked
Ilena Rose
Thursday, March 17, 2005, 12:00 A.M. Pacific
Autism, mercury possibly linked
By Thomas H. Maugh II
Los Angeles Times
Texas researchers have found a possible link between autism and
mercury in the air and water.
Studying individual school districts in Texas, the epidemiologists
found that those districts with the highest levels of mercury in the
environment also have the highest rates of special-education students
and autism diagnoses.
The study does not prove that mercury causes autism, cautioned the
lead author, Raymond Palmer of the University of Texas Health Science
Center in San Antonio, but it provides "provocative" clues that should
be investigated.
"Mercury is a known neurotoxin," said Dr. Isaac Pessah of the
University of California, Davis' M.I.N.D. Institute, who was not
involved in the study. "It's rather intriguing that the correlation is
so positive. It makes one worry."
California has the highest environmental burden of mercury of any
state and it has what appears to be the highest rate of autism,
although some critics attribute this perceived high rate to enhanced
surveillance associated with the state's special-education program.
Autism is a severe developmental disorder in which children seem
isolated from the world around them. There is a broad spectrum of
symptoms, but the disorder is marked by poor language skills and an
inability to handle social relations.
The incidence of autism has grown in the past 20 years, from about one
in every 2,000 children to as high as one in every 166. Researchers
have been hard-pressed to explain the increase, but many believe
mercury to be the culprit.
The purported link between autism and mercury has been a subject of
intense debate. In the past it centered primarily on the
mercury-containing preservative thimerosal, which was once widely used
in vaccines.
Many parents have argued that thimerosal causes autism because their
children seemed to develop the neurological disorder shortly after
they received childhood vaccinations.
That link largely has been discredited, and researchers are beginning
to look at the potential effects of the metal from other sources.
Mercury is routinely released from power plants burning fossil fuels,
and it spreads widely in air and water. Much of the fish consumed in
some regions is contaminated with mercury.
In the new study, Palmer and his colleagues used EPA data about the
environmental release of mercury in 2001 in Texas' 254 counties and
correlated that with the number of special-education cases and autism
diagnoses in the nearly 1,200 school districts. Texas is fourth in the
annual amount of mercury released into the environment, trailing
California, Oregon and West Virginia.
The study, which will appear in the peer-reviewed journal Health &
Place, found that every 1,000 pounds of mercury released into the
environment produced a 43 percent increase in special-education
services and a 61 percent increase in the autism rate.
The one exception to the rule was Brewster County, which had a high
autism rate but did not report significant mercury levels to the EPA.
When Palmer investigated, however, he found that the county had been
home to one of the largest mercury mines in the nation.
Much more work will be required to determine whether mercury is
actually the causative agent in the disorder.
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The mercury issue is another Disinformation Campaign by the
inappropriately named "quackwatch" ... led by a former, never board
certified 'psychiatrist' ...