What Is Thimerosal?
May 19, 2004
Thimerosal is a mercury-based compound that has been used since the 1930s as a preservative to prevent the contamination of multi-dose vials of vaccines.
Thimerosal is controversial because high levels of mercury are known to be toxic to the nervous system and other tissue. In 1999, following a recommendation from the U.S. Public Health Service and the American Academy of Pediatrics, vaccine manufacturers began to remove thimerosal from vaccines.
Today, all routinely recommended pediatric vaccines manufactured for the U.S. market are free of thimerosal or contain only trace amounts. Federal health officials say these vaccines are safe.
In 2001, the Institute of Medicine said it could not find enough evidence to accept or reject "causal relationships" between exposure to thimerosal in vaccines and neurological disorders such as autism. In a report Tuesday, the institute said new evidence shows there is no link.
More than 3,700 thimerosal-related claims are pending at the National Vaccine Injury Compensation Program, which is administered by the federal government. Since 1989, the program has not paid a single thimerosal-related claim.
- John A. MacDonald