Vaccine Ingredients – Thimerosal
July 24, 2024
Some people have worried that thimerosal, an ethylmercury-containing preservative in some multi-dose preparations of influenza vaccine, could cause mercury poisoning either in children or affect the unborn children of pregnant women who receive this vaccine. But, for many reasons, thimerosal contained in vaccines is not harmful.
All mercury isn't the same: Methylmercury vs. ethylmercury
Mercury is a naturally occurring element found in the earth's crust, air, soil and water. Since the earth's formation, volcanic eruptions, weathering of rocks and burning of coal have caused mercury to be released into the environment. Once released, certain types of bacteria in the environment can change mercury to methylmercury. Methylmercury makes its way through the food chain in fish, animals and humans. At high levels, it can be toxic to people.
Thimerosal contains a different form of mercury called ethylmercury. Studies comparing ethylmercury and methylmercury suggest that they are processed differently in the human body. Ethylmercury is broken down and excreted much more rapidly than methylmercury. Therefore, ethylmercury (the type of mercury in the influenza vaccine) is much less likely than methylmercury (the type of mercury in the environment) to accumulate in the body and cause harm.
Because the names of these two chemicals vary by only a single letter, it is difficult to believe they could be very different; however, if you think about ethanol and methanol (also known as ethyl alcohol and methyl alcohol), you will see that the difference can be dramatic – ethanol is what we drink at a party, whereas methanol, added to some types of gasoline and antifreeze, is poisonous if consumed.