Thimerosal Controversy

Thimero…what?

Have you heard of Thimerosal? I sure haven’t. So, before we can understand why there is hesitation when this compound is found in vaccines, we should explore what it is. Thimerosal is an organic mercury compound, an organomercurial, created in the 20th century to combat bacterial presence in vaccines. Before such compounds were brought into the world of vaccines, bacterial contamination of vaccines was a real problem resulting in sickness and even death is some cases when people, usually children, were vaccinated with toxic batches. These batches may have been stored at the wrong temperature or removed from the stock solution aseptically, but regardless it was really dangerous to be vaccinated with a contaminated batch. Thus, scientists started using germicides to combat these bacteria and originally, the germicides themselves were causing harmful side effects. For example, mercury chloride was used despite its harmful skin irritations. So when scientists developed this new class of mercuries that were not toxic, it was a big thing and lead to a lot safer vaccination.

So What’s the Problem?

The controversy surrounding this compound is kind of cloudy. So let us rewind some more. After Thimerosal was introduces around WWI, it went under extensive testing to determine if it was toxic, how much could be tolerated, how effective it was against certain bacteria, and if there were any side effects…..in rabbits. After startling results of a pretty high dose being tolerated by the animals with no impairments to their life, Thimerosal became very promising and made its way into the medical world. According to Jeffrey Baker with the U.S National Library of Medicine, after about 50 successful years in the field, questions were raised concerning Thimerosal after organic mercury poisoning, usually from fish, hit populations and caused illnesses. This fear was addressed when it was determined that the type of mercury in fish stays in the body system, while the mercury in Thimerosal does not and is flushed out, but people still were not fans of vaccines with this compound. Studies began claiming the toxic effects of Thimerosal when used as a topical agent for pain, even though the levels of the drug in topical use were far beyond those in a vaccine. Despite this inconsistency in claims, there was only one child vaccine with Thimerosal in it by the 1970’s.

The real panic came with Thimerosal, an ethylmercury, became associated with methylmercury, a compound known to affect the developing brains of infants and children. After a devastating event of the coast of Japan, more questions were raised. A large factory deposited its waste into the shore and it was converted to Methylmercury that killed fish, seagulls, cats, and affected humans who ate infected fish. Children born to asymptomatic parents were affected more severely than those exposed and the photos of symptoms circulated the world and made their way to the U.S. After this event and many others linked to “mercury”, extensive research was conducted to define a safe amount of “mercy” for the average adults and for pregnant women. Despite the word “mercury” being an umbrella term and not all mercuries acting the same in the human body, it was ruled that Thimerosal would be removed from vaccines because the levels in the vaccine were too high for fetus in vaccinated mothers.

Somewhere along the way, the debate concerning vaccinations and their linkage to autism came about and a group called the “mercury moms” blamed Thimerosal for the disabilities of their children. This group got political with it and was a large influence on the removal of Thimerosal from vaccines. This essentially nailed the lid on the coffin for Thimerosal use.

So Now What?

Thimerosal is still seen in vaccines, like the flu-shot, because of its long outstanding record of preventing bacterial growth and making vaccine batches toxic. I think the reason there are alternative vaccines for anti-Thimerosal populations is because the push to encourage vaccination and to eradicate vaccine hesitancy is so great that the scientific society is willing to find alternative ways to bring as many people of the vaccine train as possible. According to the FDA, the reason for the decline in use all together is due to scientific advancements in single-dose vaccines to eliminate the need for long periods of storage. I find it interesting that the FDA website does include the fact, “The CDC’s ACIP does not preferentially recommend vaccines that do not contain thimerosal for any populations.” which kind of rips the lid off the coffin for Thirmosal emphasizing that it is no more or less effective than other vaccines for any type of person, regardless of age.