The EPA has raised concerns regarding mercury exposure. These concerns have been in the context of chronic exposure to methyl mercury in milligram amounts. In contrast, blood plasma-derived products (except anti-venoms) containing ethyl mercury are usually given as one or two injections. Furthermore, the ethyl mercury content of these products is in the form of a preservative, thimerosal (thiomersal), which breaks down to form ethyl mercury in microgram amounts.
In the past, plasma-derived products made in multiple-use vials, e.g. Immune Globulin (Human), used for Hepatitis A prophylaxis, contained a preservative, such as ethyl mercury-containing thimerosal, to avoid contamination. This type of multi-dose presentation has been discontinued for all licensed plasma derivative products.