FAQ's About Mercury (Thimerosal) in Vaccines
Q: Is it true that all the mercury has been removed from vaccines? How much mercury is in the flu shot and other recommended vaccines? Should I go out of my way to find a thimerosal-free flu shot and where can I find one?
A: Even though most of the vaccines routinely administered to infants in the United States no longer contain more than trace amounts of ethyl mercury in the form of Thimerosal, the entire vaccine supply is not Thimerosal-free. The most notable exception to this is the seasonal influenza (flu) vaccine. Most, but not all, influenza vaccine still contains Thimerosal. Notably, many vaccines used in third world countries are mercury containing and exceed safety guidelines established in the United States.
Information on vaccines that contain significant amounts of Thimerosal can also be found on the Food and Drug Administration's website and Johns Hopkins Bloomberg School of Public Health's Institute for Vaccine Safety website.
Manufacturers began voluntarily removing Thimerosal from pediatric vaccines around 2000. It is assumed that most pediatric vaccines containing Thimerosal were “off the shelves” by 2003. (No vaccines were recalled.) Even so, most infants are still routinely given Thimerosal-containing influenza vaccine even though there are Thimerosal-free and vaccines with trace amounts of Thimerosal. Infants receiving a Thimerosal-containing influenza vaccine are dosed at 6 months with 12.5 mcg of ethyl mercury and at 7 months with an additional 12.5 mcg. Adult Thimerosal-containing vaccines contain roughly 25mcg. These Thimerosal-containing version exceed federal safety guidelines mentioned earlier. For more information, you can review a special write-up on the NVIC website, titled "Aluminum and Vaccine Ingredients: What Do We Know? What Don't We Know?"
Depending on the vaccines administered, at six months of age, infants today born to mothers who received flu vaccine during pregnancy could receive up to 71 mcg of ethyl mercury compared to 187.5 mcg prior to efforts to decrease the amount of thimerosal in infant vaccines. Additionally, the CDC guidelines recommend that all children receive an annual influenza vaccine beginning at 6 months of age. As a result, the total amount of thimerosal given to children under 5 years of age is almost what it was prior to 2000.
There are other sources of mercury exposure in infants. Specifically, it should be recognized that influenza vaccine recommended for pregnant women and some rhogam preparations contain ethyl mercury in the form of thimerosal. Total mercury burden include other sources including dental amalgams (silver fillings), food especially some types of fish, and air pollution from coal-fired power plants and wildfires.
Concerns regarding mercury in vaccines were addressed in a letter published by the Journal Pediatrics on March 13, 2008 (update 3/17/2016: letter is no longer available online). As noted in the letter, parents and pregnant women may want to consider the following data and make an informed decision.
- 0.5 parts per billion (ppb) mercury = Kills human neuroblastoma cells (Parran et al., Toxicol Sci 2005; 86: 132-140).
- 2 ppb mercury = U.S. EPA limit for drinking water.
- 20 ppb mercury = Neurite membrane structure destroyed (Leong et al., Neuroreport 2001; 12: 733-37).
- 200 ppb mercury = level in liquid the EPA classifies as hazardous waste.
- 25,000 ppb mercury = Concentration of mercury in the Hepatitis B vaccine, administered at birth in the U.S., from 1990-2001.
- 50,000 ppb Mercury = Concentration of mercury in multi-dose DTaP and Haemophilus B vaccine vials, administered 4 times each in the 1990's to children at 2, 4, 6, 12 and 18 months of age.
- 50,000 ppb Mercury = Current "preservative" level mercury in multi-dose flu (94% of supply), meningococcal and tetanus (7 and older) vaccines. This can be confirmed by simply analyzing the multi- dose vials.
NVIC does not maintain a list of places that stock mercury-free flu shots, as availability and locations differ from state to state. We recommend that you call doctor's offices, public health clinics, pharmacies or your state's health department for this information.