Mercury Levels Same in Autistic, Other Children
Fish Consumption Predicted Levels Best, Researchers Found
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
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,
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
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
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