“It’s indisputable that autism is on the rise among children,” Senator John McCain said while campaigning recently in Texas. “The question is, What’s causing it? And we go back and forth, and there’s strong evidence that indicates that it’s got to do with a preservative in vaccines.”

With that comment, McCain marked his entry into one of the most politicized scientific issues in a generation.

McCain is correct that autism diagnoses have increased in recent decades; no one disputes that. He is on much shakier ground when talking about the preservative as a cause…

Several large-scale studies have found no evidence of a link between thimerosal and autism, and medical groups including the Centers for Disease Control and Prevention, the Institute of Medicine and the American Academy of Pediatrics have publicly stated as much. In January, California reported an increase in autism cases, despite the removal of thimerosal from most vaccines…

Nothing like sucking up for votes.