Study Links Autism to
Mercury
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.
“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. The
article is in the journal Health &
Place.
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.
“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.”
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.”
“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.
“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.”
