evidence: Stehr-Green P, Tull P, Stellfeld M, et al. Autism and thimerosal-containing vaccines: lack of consistent evidence for an association. Am J Prev Med 2003;25:101-106. The authors compared the prevalence and incidence of autism in California, Sweden and Denmark with average exposures to thimerosal-containing vaccines between the mid-1980s and late-1990s. They found that exposure to thimerosal-containing vaccines was not associated with the increase in rates of autism in young children being observed worldwide. [...] The authors evaluated the incidence of autism in children born in Denmark between 1990-1996 who received either thimerosal-containing vaccines or thimerosal-free preparations of the same vaccine. They found that the incidence of autism or autistic spectrum disorders did not differ significantly between the two groups.