In July 2006 I posted a summary of findings which, to my mind, refuted the concept that thimerosal - the mercury-based preservative once used in children's vaccines - causes autism. That was clearly not enough to convince some upset parents (and others) that the preservative was responsible for the dread disease. They have just attacked a further conclusive study reported in the January Archives of General Psychiatry.

The prevalence of autism in California for children aged 3 to 5 increased from 1995 through 2007. On the other hand, thimerosal was removed from childhood vaccines, starting in 1999, and removal was almost complete by 2001. These finding reinforce the view that mercury has no role in the causation of autism. As Dr Fombonne of Montreal Children's Hospital said in 2004: "Parents of autistic children should be reassured that autism in their child did not occur through immunizations. Their autistic children, and their siblings, should be normally vaccinated, and as there is no evidence of mercury poisoning in autism, they should avoid ineffective and dangerous 'treatments' such as chelation therapy for their children." If you're atill in doubt, go to Quackwatch.