In the early 20th century, there were a lot of cases of children developing deadly bacterial infections once they received all of their vaccinations. Due to this outbreak, preservatives were added to vaccinations contained in multi-dose vials since the 1930’s, in order to prevent this bacteria from forming. (http://www.chop.edu/service/vaccine-education-center/vaccine-safety/vaccine-ingredients/thimerosal.html)
Thimerosal is one of those preservatives that were added to vaccines, and it contains mercury. Mercury is a “heavy silvery-white element occurring principally in cinnabar.” (http://dictionary.reference.com/browse/mercury) Mercury poisoning can result from exposure to water soluble forms of mercury. (http://en.wikipedia.org/wiki/Mercury_(element)). Recent research has led to mercury being removed from vaccinations, all except the influenza, or flu vaccination. The whole debacle with parents claiming thimerosal was to blame for their children developing autism spread widely throughout the news, and so thimerosal was eventually removed from these childhood vaccinations. (http://www.chop.edu/service/vaccine-education-center/vaccine-safety/vaccine-ingredients/thimerosal.html) Doctor’s offices do offer non-thimerosal containing flu shots, for those of you who are still leery about receiving a flu shot with mercury in it, and you can visit http://www.cdc.gov/flu/protect/vaccine/vaccines.htm to find which flu shots contain thimerosal or not. These flu-shots are single dose shots, so they do not need the thimerosal for preservation. The reason for the multi-dose shots is that a lot of people receive the flu-shot in a short period of time, usually in the fall/winter, and they need to produce the vaccines in high volume. The removal of thimerosal was enacted starting around 1997, when the FDA started to determine what food and drugs contained the ingredient. Three vaccinations at the time, DTaP, hepatitis B, and Haemophilus influenzae (Hib) all contained thimerosal. The combined exposure of mercury if a child were to receive all three of these vaccinations was higher than the recommended amount of exposure, around 187.5 ug. (see table below)
|EPA||65 ug||89 ug||106 ug|
|ATSDR||194 ug||266 ug||319 ug|
|FDA||259 ug||354 ug||425 ug|
|Exposure limits for mercury in infants less than or equal to 6 months of age by percentile body weight established by the Environmental Protection Agency (EPA), the Agency for Toxic Substance Disease Registry (ATSDR), and the Food and Drug Administration (FDA)|
Due to these findings, thimerosal was removed from all childhood vaccinations as mentioned previously. That is why we encourage parents to get their children vaccinated, because the vaccinations do not include thimerosal anymore, and the one that does (influenza), has alternative non-thimerosal shots available.