Mercury Levels Same in Autistic, Other Children

Last Updated on January 4, 2023 by Admin

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Fish Consumption Predicted Levels Best, Researchers Found

By
Kathleen Doheny

WebMD Health News

Reviewed By
Louise Chang, MD

Oct. 19, 2009 — Blood levels of mercury are similar in children with autism, those with other developmental problems, and
those who are developing typically, according to a new study.

“There has been discussion about whether children with autism have high
levels [of mercury],” says the study’s lead author, Irva Hertz-Picciotto, PhD,
an epidemiologist, professor, and chief of environmental and occupational
health at the University of California, Davis, and a researcher at the MIND
Institute there.

Hertz-Picciotto cautioned that her recent study does not examine whether
mercury plays a role in causing the disorder, which has been the focus of
ongoing debate. Major studies of children who were given vaccines with the
mercury-containing preservative thimerosal (now phased out of most vaccines
given to children) don’t find a link between the vaccines and autism, but some
organizations led by parents of autistic children doubt those conclusions.

The blood levels in the study were taken after a child had already received
a diagnosis of autism, a developmental disorder now believed to affect one in
91 U.S. children and marked by difficulty in communication, social interaction,
and learning.

Some took exception with the new study.

“Measuring blood levels of mercury is a useless way to assess chronic
damage or pathology from mercury, as it clears the bloodstream relatively
rapidly,” says Jim Moody, a director for the Coalition for SafeMinds (Sensible
Action for Ending Mercury-Induced Neurological Disorders), an organization that
investigates the risks of mercury exposure.

Mercury Levels and Autism: Study Details

Triggering the research, Hertz-Picciotto says, is that some researchers have
thought children with autism may have higher levels of mercury in their blood
because their bodies don’t get rid of it it as efficiently as other
children and that buildup might be contributing to the problems.

But others have speculated that children with autism may have lower blood
levels of mercury because the mercury is sequestered in their brain, she
says.

For the study, Hertz-Picciotto and her colleagues compared the blood levels
of mercury in 249 children with autism or autism spectrum disorder, in 143
typically developing children and in 60 children with developmental delays
other than autism spectrum disorder. Children were enrolled into the study from
2003 to 2006.

The children were part of the Northern California-based Childhood Autism
Risks from Genetics and the Environment (CHARGE) study, for which
Hertz-Picciotto is the principal investigator. Children aged 24-60 months are
enrolled in the study, in which researchers are looking at a variety of
exposures and their possible association with the disorder. Some of the
participants have autism spectrum disorders, some have other developmental
disorders, and a third group of children is typically developing, serving as
study controls.

Her team looked at a variety of sources of mercury in the environment,
including consumption of fish, use of personal care products that contain
mercury such as nasal sprays and earwax removal products, and vaccinations.
They also looked at whether children had mercury-based dental amalgam
fillings.

Mercury Levels: Study Findings

The autism group did not differ from the typically developing group in the
level of mercury circulating in their blood after the researchers adjusted for
the sources of mercury, Hertz-Picciotto says.

“There are no obvious differences in the circulating levels of mercury”
among the three groups, she says.

“Unadjusted, those with autism had lower levels as it turns out,” she says.
That may be due to a lower consumption of fish among those with autism, she
says, perhaps because of the tendency to be picky eaters and adhere to the same
foods.

The average levels of mercury were 0.24 micrograms per liter for the
typically developing children, 0.26 micrograms per liter for those with autism
or autism spectrum disorder, and
0.16 micrograms for those with other developmental disorders, she found.

To put that in perspective, Hertz-Picciotto says the Environmental
Protection Agency considers a level of 5.8 micrograms per liter not risky
for pregnant women. There is no
specific standard set for children, she says.

Mercury Levels and Autism: Other Opinions

The new study drew mixed reactions from experts. The new findings “should
be reassuring to parents,” says Geraldine Dawson, PhD, chief science officer
for Autism Speaks and a research professor at the University of North Carolina,
Chapel Hill.

“There has been concern by some parents that just the normal kind of
exposure to mercury in our environment … might have a bigger effect on
children with autism, and they might have specific trouble metabolizing
mercury,” Dawson says.

“This [study] suggests that children with autism are not retaining high
levels of mercury in their body,” she says. “This study does not address the
issue of whether mercury played a role in causing autism.”

Sallie Bernard, co-founder and executive director of the Coalition for
SafeMinds, called the study interesting but limited in its worth. “I think this
is a study that adds to the literature on mercury and autism,” she says. “But
because it is looking at post-diagnosis exposure and does not investigate
unique susceptibility and different toxicokinetics [such as absorption] of
children with an autism spectrum disorder, the value of the study in
understanding the role of mercury in autism is limited.”

In a statement released by SafeMinds in response to the study, Bernard calls
for research to look at how children with autism may handle mercury exposures
differently, pointing to research suggesting children with autism may be more
susceptible to stressors such as mercury.


autism s1

QUESTION


Autism is a developmental disability.
See Answer

References

SOURCES: Irva Hertz-Picciotto, PhD, epidemiologist, professor, and chief of environmental and occupational health, University of California, Davis; researcher, MIND Institute.

Geraldine Dawson, PhD, chief science officer, Autism Speaks; research professor, University of North Carolina, Chapel Hill.

Hertz-Picciotto, I. Environmental Health Perspectives, online, Oct. 19, 2009.

Sallie Bernard, co-founder and executive director, Coalition for SafeMinds, Aspen, Colo.

Jim Moody, director, Coalition for SafeMinds.

©2009 WebMD, LLC. All Rights Reserved.

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