In a commentary accompanying the study, Dr. Eric Fombonne called the data "a clear and unambiguous test."
"Parents of autistic children should be reassured that autism in their child did not occur through immunizations," wrote Fombonne, a psychiatrist at Montreal Children's Hospital who was not involved in this study. He has provided advice to vaccine manufacturers in the past but has received no research funding from them, he said.
Steve M. Edelson, an experimental psychologist who is director of the Autism Research Institute, a nonprofit organization in San Diego, said the study, along with evidence from previous research, argued against thimerosal as the major culprit in autism.
But he added that thimerosal may still play some role. Edelson said such large-scale analysis could overlook smaller groups of children, who for whatever reason have a particular vulnerability to mercury.
He said more solid evidence can only come from laboratory studies, such as postmortem analyses of the brains of autistic children.
The National Autism Assn. criticized the study, saying that some children may still be exposed to mercury through either flu shots or trace amounts in other vaccines. The group also said that some vaccines containing thimerosal had expiration dates as late as 2005 and may have been used up to that point.
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jia-rui.chong@latimes.com
