THIMEROSAL….Does thimerosal in infant vaccines cause autism? As near as I can tell it’s impossible to say. The basic evidence in favor is that a few years after thimerosal-based vaccine use increased in the late 80s, diagnoses of autism also began to skyrocket. This is certainly suggestive that thimerosal might be one of the triggering causes of autism (and possibly other neurological disorders as well).
Unfortunately, because the data is sparse and there are lots of other possible explanations, there’s no way to say for sure that thimerosal is really at fault. Robert F. Kennedy Jr. has taken up the cause recently and believes not only that thimerosal is dangerous but that the federal government, in cahoots with the vaccine industry, has been covering up the danger. (A more detailed version of his case is here.) Lindsay Beyerstein is skeptical of RFK’s charges (here and here), and the New York Times reviews the bidding in a front page article today.
It’s easy to understand the emotion behind this subject, but it’s less clear why Kennedy decided to make it front page news right now. After all, as the Times points out, we’re going to know for sure pretty shortly:
In “Evidence of Harm,” a book published earlier this year that is sympathetic to the notion that thimerosal causes autism, the author, David Kirby, wrote that the thimerosal theory would stand or fall within the next year or two.
Because autism is usually diagnosed sometime between a child’s third and fourth birthdays and thimerosal was largely removed from childhood vaccines in 2001, the incidence of autism should fall this year, he said.
Since thimerosal has already been removed from most infant vaccines, the only issue remaining is whether or not past thimerosal use caused autism. Since that’s (a) a very tricky epidemiological question and (b) one that will be answered rather clearly in the next year or two, what’s the point of continuing to argue over previous research? Is it just habit?