In February of 2009, a U.S. federal court ruled that there was no scientific evidence linking vaccines to autism.
In the new study, researchers examined medical records and conducted interviews with the mothers of 256 children with an autism spectrum disorder and 752 children matched by birth year who did not have autism. The children were all members of three health care management organizations in California and Massachusetts.
Researchers also gathered information about the manufacture and lot number of the vaccines that the children received, to determine how much thimerosal they were likely exposed to.
Children in the highest 10 percent of thimerosal exposure, either prenatally or between infancy and 20 months, were no more likely to have autism, an autism spectrum disorder or autism spectrum disorder with regression than children in the lowest 10 percent of exposure.
"This study adds to a large body of evidence indicating that early thimerosal exposure through vaccination does not cause autism," said Geraldine Dawson, chief science officer for a leading advocacy group, Autism Speaks. Dawson was not involved with the research.
She urged parents to have their children vaccinated.
"We encourage parents to have their children vaccinated and to establish a trusting relationship with their child's pediatrician so they can discuss any concerns they have," Dawson said.
The U.S. Food and Drug Administration has more on thimerosal.
SOURCES: Frank DeStefano, M.D., M.P.H., director, immunization safety office, U.S. Centers for Disease
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