A new study appears to fully sever the alleged link between the mercury-containing thimerosal and autism. Rates of the neurological disorder continued to grow even after thimerosal was removed from all childhood vaccines in 2001, the study found. It's the first hard data to show that the preservative shouldn't be implicated in the rapid and troubling increase in cases of autism.
Published in the Archives of General Psychiatry, the study analyzed autism rates over a 12-year period. They rose continuously. If thimerosal did contribute to the disorder, rates should have dropped from 2004 to 2007, the researchers said. "Whatever the explanation for this increase in children with autism, exposure to mercury in vaccines is not it," says Robert Schechter, the study's lead author.
Activist parents, however, maintain that thimerosal may still play a role. The National Autism Association began criticizing the study as soon as it was released, saying they still believe mercury plays a role. For instance, they said, pregnant women are now more likely to get flu shots, which still contain thimerosal--and 25 micrograms of mercury. The association again asked the CDC and NIH to study the level of heavy metals in children's bodies.
Meanwhile, autism researchers say they'd like to concentrate on other possible causes. Said Myrna Siegel, director of the Autism Clinic at University of California-San Francisco, "People like me are exasperated that so much money and attention has gone into disproving the mercury hypothesis when it could have been going toward treatment and research."