evidence: Some vaccines may also contain adjuvants, preservatives, stabilizers and residual byproducts from the manufacturing process. All of these components are safe in the concentrations used in vaccines. Many of them are common and can be found in our bodies, drinking water, food or other products we ingest or use regularly. [...] Preservatives are typically added to multidose vaccine vials to prevent contamination once a vial is opened. Although anti-vaccine groups falsely claim the tiny amounts of thimerosal, a preservative that contains ethylmercury, in vaccines is dangerous, it has been shown not to be harmful. Ethylmercury is not the same as methylmercury, a kind of mercury found in some fish and animals that can be toxic at high levels. Ethylmercury is safer because it’s broken down and excreted faster from the body. There is no link between thimerosal in vaccines and autism. Since 2001, thimerosal has not been used in any childhood vaccines in the U.S. other than multidose flu shots.