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July 18, 2003

U.S. IMMUNIZATION NEWS

“Autism and Thimerosal-Containing Vaccines”

American Journal of Preventive Medicine (www.elsevier.com/locate/amepre)

(06/30/03) Vol. 25, No. 2, P. 101; Stehr-Green, Paul; Tull, Peet; Stellfeld, Michael

The increased rate of autism in the United States during the 1990s was loosely connected in theory with the use of the preservative Thimerosal, which contains organic mercury in doses exceeding existing guidelines, in childhood vaccines.  The Institute of Medicine Immunization Safety Review Committee analyzed immunization data from Sweden and Denmark, which are known to keep high-quality records on everything from recommended vaccination schedules to occurrence of autism-like disorders, and determined that Swedish children between the ages of two years and 10 years were increasingly diagnosed with autism with a peak of 9.2 children in every 100,000 children in 1993.  However, during this same time period, the country significantly decreased and eliminated use of Thimerosal in childhood vaccines.  The data for Denmark, similar to Sweden, showed an increase in autism cases to a peak of 181 cases per 100,000 children in 1999, yet an elimination of Thimerosal from vaccines by 1992.  Because Sweden and Denmark only kept records for inpatient diagnosis of autism, the results are slight skewed; however, the data still contradicts an assumption made by researchers in California that Thimerosal was responsible for a rise in the rate of autism.  The Centers for Disease Control and Prevention plans a more robust study to fully understand the reasons behind the rise in autism in the 1990s.