McCAIN’S JUNK SCIENCE….Here’s the latest from John McCain:

At a town hall meeting Friday in Texas, Sen. John McCain, R-Ariz., declared that “there’s strong evidence” that thimerosal, a mercury-based preservative that was once in many childhood vaccines, is responsible for the increased diagnoses of autism in the U.S. — a position in stark contrast with the view of the medical establishment.

….McCain said, per ABC News’ Bret Hovell, that “It’s indisputable that (autism) is on the rise amongst children, 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.”

This is from Jake Tapper, who, to his credit, calls this for the nonsense on stilts that it is. There’s never been strong evidence in favor of the thimerosal/autism connection, and what little evidence there was has practically disappeared over the past couple of years as further studies have been done. The odds of thimerosal being responsible for autism are now slim and none, and perpetuating this myth does real damage — both to the cause of autism research and to the millions of parents who hear this and decide to keep their children from receiving the normal complement of childhood vaccines.

So what happened here? Why did McCain perpetuate this rubbish without even a smidgen of doubt in his voice? Was he pandering to some constituency or other? Was he just making shit up because he didn’t really know anything about the subject? Was he misinformed by own staff about this? Unfortunately, my guess is that the correct answer here is “making shit up,” a quality that McCain has shown an unfortunate weakness for in the past. It’s just another indication that when it comes to anything outside of the few pet issues he cares about, McCain really can’t be bothered to take an interest. Not a great quality for the leader of the free world.

Via Mark Kleiman.

UPDATE: James Joyner suggests a fourth possibility: McCain gets his opinions on thimerosal from Don Imus. Great.