US presidential hopeful John McCain has blamed vaccine preservative thimerosal for rising incidence of autism.
'It's indisputable that autism is on the rise among children,' Senator John McCain, tipped to become the Republican presidential candidate, 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.'
While some parents' groups and lawmakers assert that the preservative, which contains mercury and is called thimerosal, has caused an epidemic of new autism cases, most mainstream researchers strongly disagree.
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.
In February, an international team of researchers, analyzing blood samples from vaccinated children, found that blood levels of ethyl mercury 'fell rapidly and had largely returned to baseline levels by Day 11 after vaccination.' Those levels fell much more rapidly, for instance, than levels of the mercury people absorb by eating fish — suggesting that the injected thimerosal is less likely to build up in the blood, the researchers concluded.
Still, the parent groups raising concerns about the dangers of vaccines have not wavered in their conviction, and if anything have become more skeptical of government pronouncements on the issue.
Hence by stoking up the controversy, McCain might have succeeded in projecting himself as a very concerned politician.