Evidence review of claims linking thimerosal in vaccines to autism and neurodevelopmental disorders.
"Thimerosal, a mercury-based preservative used in some vaccines, causes autism and other neurodevelopmental disorders. The mercury in thimerosal is toxic to the developing brain."
1. Mercury toxicity: Elemental and methylmercury are known neurotoxins. Some argue that ethylmercury (in thimerosal) should be treated similarly.
2. Ecological correlations: Some point to the increasing vaccine schedule correlating with increasing autism rates.
1. Different mercury compounds: Ethylmercury (in thimerosal) is metabolized and excreted differently than methylmercury. It does not accumulate in the brain like methylmercury.
2. Thimerosal removed in 2001: Thimerosal was removed from all routine childhood vaccines in the U.S. by 2001. Autism rates have continued to rise since then, providing strong evidence against the causal link.
3. Multiple epidemiological studies: IOM (2004), CDC, and independent researchers have found no credible evidence linking thimerosal to autism.
Confidence Level: HIGH