Mercury Levels Not Abnormal in Autistic Children

Oct. 20 -- MONDAY, Oct. 19 (HealthDay News) -- A new study finds no differences in blood mercury levels between children who are developing normally and those diagnosed with autism or autism spectrum disorders.

The findings, appearing online Oct. 19 in the journal Environmental Health Perspectives, may quell some of the debate surrounding mercury and autism.

The researchers did not, for instance, look at whether mercury might play a causal role in this group of developmental disorders.

"This is an excellent study that has addressed a very important question for many families about the role of mercury [in autism]," said Dr. Patricia Manning-Courtney, medical director of The Kelly O'Leary Center for Autism Spectrum Disorders at Cincinnati Children's Hospital Medical Center. "It's a very clear study [in] that no differences in mercury were seen. Is it going to put the questions to rest? I think no. It's another important contribution to the large body of knowledge on this topic, but I think it will still be an area of great controversy."

Previous studies have shown higher blood mercury levels in people with autism, but the results, along with the quality of the studies, have been inconsistent.

One of the biggest controversies claims that vaccines containing the preservative thimerosal, which contains mercury, might cause autism.

But thimerosal is no longer used routinely in children's vaccines and, earlier this year, a U.S. court ruled that there is no scientific evidence that childhood vaccines such as the measles-mumps-rubella vaccine caused autism in children of parents seeking compensation from a federal fund.

The authors of this study wanted to fill one gap in the research: a lack of good evidence comparing mercury levels in children with autism and children without autism.

The authors looked at 452 children aged 2 to 5, who either had autism/autism spectrum disorder, developmental delays other than autism (such as Down syndrome), or who were developing normally.