New California Study on Children’s Blood Mercury Levels Leaves Unanswered Questions About Mercury’s Role in Autism.
Posted Oct 20 2009 12:00am
SafeMinds Calls for Studies on Early Exposures and Altered Mercury Susceptibility, End to Mercury in Influenza Vaccines.
Monday, October 19, 2009 – The science journal Environmental Health Perspectives released findings from the Childhood Autism Risks from Genetics and the Environment (CHARGE) Study comparing blood mercury levels in children with and without an autism spectrum disorder. The study looked only at the recent exposures reflected in blood mercury concentrations. It found that current blood mercury levels were lower in the autism group and, given equivalent exposures, blood levels were the same relative to typical children. It observed that blood levels in the typical group were comparable to those reported in the large CDC NHANES study. The authors were careful to note that the study did not investigate and was therefore unable to determine whether earlier exposures played a role in autism onset or whether the group with autism had increased susceptibility to the mercury exposures, regardless of when the exposure occurred.
The study, Blood Mercury Concentrations in Children with and without Autism, was funded by the National Institute of Environmental Health Sciences and lead by Irva Hertz-Picciotto at the University of California-Davis. Autism onset has been linked to mercury exposure occurring prior to diagnosis. This study was designed to examine whether autistic children might have higher on-going exposures that might increase the severity of the condition post-diagnosis. It also sought to determine if blood mercury concentrations might be different in autism even at equivalent exposures, suggesting altered toxicokinetics of mercury in autistic children once exposed. The authors were explicit in the paper to note that the study was not designed to examine whether exposures prior to diagnosis were higher in the autistic group, whether autistic children might have a unique susceptibility to the toxic effects of mercury, or whether some aspects of toxicokinetics other than those reflected in blood measurements are different in those with autism.