Thiomersal and vaccines
In 1999, concerns were raised in the United States about exposure to mercury following immunization. This was based on the realization that the cumulative amount of mercury in the infant immunization schedule potentially exceeded the recommended threshold set by one of the United States government agencies for methyl mercury. However thiomersal, the preservative in some vaccines, contains ethyl mercury and not methyl mercury. The Global Advisory Committee on Vaccine Safety (GACVS) first assessed this issue in a special meeting in August 2000 and concluded that there is no evidence of toxicity in infants, children or adults exposed to thiomersal (containing ethyl mercury) in vaccines. The safety of thiomersal containing vaccines continues to remain under review by the Commitee.