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April 26, 2000

Preventing Harm From Thimerosal in Vaccines—Reply

Author Affiliations

Phil B.FontanarosaMD, Deputy EditorIndividualAuthorStephen J.LurieMD, PhD, Contributing EditorIndividualAuthor

JAMA. 2000;283(16):2104-2105. doi:10.1001/jama.283.16.2101

In Reply: Dr Offit and Dr Plotkin criticize policy changes in the absence of data indicating harm from thimerosal in vaccines. There is no surveillance system in place to detect the effects of low to moderate doses of organomercurials on the developing nervous system, and special studies of children who received the highest doses will take several years to complete.1,2 Given the availability of alternative products, it was inappropriate to continue exposing infants to amounts of mercury that exceed Environmental Protection Agency guidelines, which are based on careful scientific studies and established principles for toxic exposures.1,3 Infants in less than the fifth percentile in weight for age who received all thimerosal-containing vaccines would be exposed to cumulative amounts of mercury exceeding those in the Agency for Toxic Substances and Disease Registry guidelines, and larger infants who received mercury from their mothers or other sources also would exceed these limits. Safety margins should be respected because of individual variability in susceptibility and limitations in our ability to measure subtle toxic effects.2 The ethylmercury in thimerosal is neurotoxic and in the absence of data to the contrary, experts agree that the potential toxicity from ethlymercury should be considered equivalent to that from methylmercury.4