Senator John McCain, while campaigning in Texas, recently said that "It’s indisputable that autism is on the rise among children." Nothing wrong with that, but he continued, "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."

In fact, that is recently debunked myth. The rise in autism cases is not yet explained, but there is no link to the mercury-containing preservative thimerosal found in some vaccines.

Rates of children suffering from autism in California have risen despite the removal of the preservative thimerosal from childhood vaccines in 2001, researchers said in a study published in January in the Archives of General Psychiatry, a publication of the Journal of the American Medical Association. Researchers analyzed autism rates in young children over a 12-year period and discovered the first hard evidence that thimerosal plays no role in autism.  

It seems that removing thimerosal from all recommended infant vaccines as a precautionary measure in March 2001 had no effect on reducing the number of children suffering from autism. The only childhood vaccines that contain more than trace amounts of thimerosal are multiple-dose vials of some flu vaccines.

A previous look on data referring of thimerosal affecting children from 2001 suggested there was a decline in autism beginning with 1994. The new data from March 2007 did not reflect such decline. Researchers from the California Department of Public Health studied the prevalence of children with autism in California from 1995 through 2007. They discovered that the rate of all developmental disabilities increased from 504 to 905 per 1,000 live births.

Researchers believe that "there is an environmental source" linked to increased rates of autism.