Thimersal..a mercury presevervative is not only in vaccines...but other injectables as well. If you are RH negative...you had at least one shot of RHOGAM per pregnancy. And if your rubella titer was low..you were probably vaccinated as well..... I got this article from the FDA site The EPA has recently raised concerns regarding mercury exposure. These concerns have been in the context of chronic exposure to methyl mercury in milligram amounts. In contrast, 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, which breaks down to form ethyl mercury in microgram amounts. In the past, 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. These were older products and most of them have been discontinued. Rho (D) Immune Globulin (Human) products are as follows: RhoGAM, Ortho Clinical Diagnostics BayRho, Bayer WinRho, Cangene RhoGAM [licensed 1968] On April 16, 2001, Ortho Diagnostics was approved by FDA to produce RhoGAM without thimerosal, and at that time, Ortho agreed to distribute only thimerosal-free product to the US market. The product has a 2-year dating period, so that material released before April 16, 2001 may still be on the market. The package insert for RhoGAM containing thimerosal (i.e., for those lots manufactured prior to April 2001) does state that this product contains thimerosal. However, there is no warning in the package insert related to thimerosal or mercury content. Regarding the total thimerosal content of the previously released RhoGAM, the product was manufactured in two doses only: the standard dose of "300 micrograms" of anti-D, and the micro-dose of "50 micrograms" of anti-D. The fill volume for both the standard dose and micro-dose products is typically between 0.6 and 0.8 mL. Preservative-containing RhoGAM contains thimerosal at 0.003%, or 30 micrograms per milliliter. Thimerosal is about 50% ethyl mercury by weight. Hence, a patient receiving a dose of RhoGAM (0.7 ml on average) will have received 10.5 microgram of ethyl mercury. There are three indications for which an Rh-negative pregnant woman would receive a significantly larger dose of RhoGAM: a fetal-maternal hemorrhage early in the pregnancy, a fetal-maternal hemorrhage greater than 15 ml of Rh+ red cells, and an Rh+ transfusion. In the first case, a single 300 microgram dose of RhoGAM, is recommended at 12-week intervals. For the second two indications, a procedure exists by which to determine the dose of RhoGAM required, based on the amount of Rho+ red cells in the maternal circulation: the Kleihauer-Betke elution test (see the AABB Technical Manual, 13th ed., pp. 507-8.) The total dose of mercury received can be calculated by multiplying the number of RhoGAM syringes administered by 10.5 micrograms. BayRho [licensed 1971] The Bayer Corporation makes a Rho (D) Immune Globulin product (BayRho) which in the past contained thimerosal; this product has been manufactured without preservative since 1996, so that no in-date BayRho contains thimerosal. Regarding the previously distributed product, the volume of a single dose of the Bayer product was approximately 0.7 ml. The thimerosal concentration was 0.01%, so the total mercury in a single dose would have been approximately 35 micrograms of ethyl mercury.