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. [...] Vaccines may also contain surfactants or emulsifiers used to keep all the ingredients blended together and prevent clumping. Anti-vaccine groups sometimes focus on an emulsifier called polysorbate 80 to spread fear. But the compound, which is safely used in vaccines, is found in much higher concentrations in many foods, including ice cream. Trace amounts of other substances from the manufacturing process sometimes remain in vaccines. For example, many vaccines are made by growing viruses or producing proteins in chicken eggs or cell lines, so vaccines may contain DNA or proteins from those cells or other products from the growth media. Similarly, inactivated vaccines may contain formaldehyde, which is used to kill viruses. Again, the amounts of these substances in vaccines are minuscule and harmless, since the antigens are purified before being put into vials. No vaccine contains fetal cells or tissue.