GLRPPR Sector Resource: Thimerosal in Vaccines
Thimerosal in Vaccines
Thimerosal is a mercury-containing organic compound (an organomercurial). Since the 1930s, it has been widely used as a preservative in a number of biological and drug products, including many vaccines, to help prevent potentially life threatening contamination with harmful microbes. Over the past several years, because of an increasing awareness of the theoretical potential for neurotoxicity of even low levels of organomercurials and because of the increased number of thimerosal containing vaccines that had been added to the infant immunization schedule, concerns about the use of thimerosal in vaccines and other products have been raised. Thimerosal has been removed from or reduced to trace amounts in all vaccines routinely recommended for children 6 years of age and younger, with the exception of inactivated influenza vaccine; a preservative-free version of the inactivated influenza vaccine (contains trace amounts of thimerosal) is available in limited supply at this time for use in infants, children and pregnant women. In this document, a discussion of preservatives, the use of thimerosal as a preservative, guidelines on exposure to organomercurials (primarily methylmercury), thimerosal toxicity, recent and future FDA actions, and the conclusions of the Institute of Medicine's most recent review of thimerosal in vaccines are presented. This narrative on thimerosal contains references to the literature and links to other sites for readers who wish additional information; for quick reference, a number of frequently asked questions (FAQs) and answers are provided.
U.S. Food & Drug Administration (FDA)
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