The study looked at 452 children between the ages of 2-5 who had either autism or autism spectrum disorder and children who were growing normally. The study included numerous interviews with families about dietary habits, use of dental amalgams, vaccines and even use of personal care products. The children had blood samples drawn at period levels.
The preliminary data showed that some autistic children had much lower levels of mercury in blood and this was accounted by the fact that that these children consumed less sea food products like fish.
After adjusting for each and every perplexing inconsistency, results of the study revealed no difference in mercury levels between autistic children and normally growing children.
"Not only do we not see differences, but the values are pretty close to national averages," said study author Irva Hertz-Picciotto, chief of environmental and occupational health and faculty member at the MIND Institute at the University of California, Davis. Since mercury does not stay in the body for more than a few months, Hertz-Picciotto added "clearly this does not tell us anything causal because all of the mercury represents exposure that had happened post-diagnosis."
One has to remember two small things before interpreting the above study. Mercury only stays in the body for a few months and is rapidly excreted. There is always a possibility that mercury may have caused the brain damage and may no longer be present in the body. If this is true, measuring levels of mercury after the fact is meaningless. Secondly, there is always the possibility that the infant may have had exposure to mercury during pregnancy – perhaps from something the mother ate. So for now, the only conclusion from this study is that mercury levels in people with autism are not high.