evidence: Vaccine ingredients do not cause autism One vaccine ingredient that has been studied specifically is thimerosal. Thimerosal is a mercury-based preservative used to prevent germs (like bacteria and fungi) from contaminating multidose vials of vaccines. Research shows that thimerosal does not cause ASD. In fact, a 2004 scientific review by the IOM concluded that "the evidence favors rejection of a causal relationship between thimerosal–containing vaccines and autism."1 [...] - Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism. JAMA. 2003 Oct 1;290(13):1763–6.