What do the latest studies say about thimerosal and autism?
"If thimerosal in vaccines were causing autism, we'd expect that diagnoses of autism would decrease dramatically after the chemical was removed from vaccines," says Eric Fombonne, MD, director of the psychiatry division at Montreal Children's Hospital and a member of the National Institutes of Health advisory board for autism research programs.
But a large study recently published in Archives of General Psychiatry found that cases of autism continued to increase in California long after 2001, when thimerosal was removed from most childhood vaccines in the U.S. (it's still found in some flu shots). "Not only did cases not decrease -- but they continued to rise," says Fombonne. "That tells us that something else must be responsible for rising rates of autism in this country."
This study is the latest in a series of many others, in other countries and populations, which drew similar conclusions. "Thimerosal was removed from vaccines in Canada in 1996 and in Denmark in 1992," says Dr. Fombonne. "Autism is still on the rise in those countries as well."
And in 2004, both the World Health Organization and Institute of Medicine each concluded no link between autism rates and thimerosal exposure after examining the health records of hundreds of thousands of children.