Thiomersal In Vaccines 

I have heard about mercury in vaccines before, but mostly from the anti-vaxxer side. As such I didn’t give it all that much thought. That is, until it was brought to my attention by last weeks episode of Real Time With Bill Maher. Above is a short exert of the interview that tells us all we need to know to begin.

Robert Kennedy claims to be not an anti-vaxxer, and I believe it. But I am frankly unsure about the rest of the claims. In the comment section, people seem to range from disbelieving to flat out opposed (sometimes with explanations). So its time to do some digging.

Thiomersal is commonly known as thimerosal in the US. According the the WHO the compound also goes by the names mercurothiolate and sodium 2-ethylmercuriothio-benzoate, and is primarily to prevent fungal and bacterial growth in vaccines in while in storage (or opened, if in multi-dose vials). It is also used to maintain a sterile vaccine production line, and sometimes to inactivate certain organisms or toxins. Its been utilized in the manufacture of vaccines and some other medical products since the 1930s.

The next part I will just let the WHO do the explaining.

Do all vaccines contain thiomersal?

Many licensed vaccines do not contain thiomersal. Such vaccines include vaccines in single-dose presentation or vaccines for which thiomersal would interfere with vaccine efficacy such as live vaccines including MMR, oral and inactivated polio, yellow fever, and BCG vaccine. These vaccines, however, when in multi-dose presentations, have to be discarded at the end of the immunization session. Other vaccines may contain trace amounts of thiomersal (<0.5 µg per dose), if the preservative has been used in the production process, but has not been added to the final product. A third group of vaccines have thiomersal added in varying concentrations (10 to 50 µg per dose) as a preservative to prevent contamination with microorganisms when formulated in multi-dose vials. Such vaccines include vaccines against diphtheria, tetanus and pertussis (DTP), diphtheria and tetanus toxoids (DT), tetanus toxoid (TT), hepatitis B, Haemophilus influenzae type b (Hib), and influenza.

Can vaccines be made thiomersal free?

Any change in the formulation of a licensed vaccine, including changes to the thiomersal content, may have an impact on the quality, safety and efficacy of vaccines and further trials are likely to be required before the reformulated product can be licensed. Replacing thiomersal with a different inactivating agent and/or preservative during the production process and/or in the final product, will require a new licensing process with a series of preclinical and clinical trials to ensure the quality, safety and efficacy of the vaccine. For vaccines used in multi-dose formulations thiomersal offers better protection from contamination than other preservatives such as 2-phenoxy ethanol.

What is 2-phenoxy ethanol? According to the NIH it is another preservative, mostly utilized in cosmetics and pharmaceuticals (though it is utilized in some vaccines).

Apparently the necessity of having the preservative thiomersal in many vaccines (to prevent microbial and fungal growth in multi-dose vials) could be reduced or eliminated by a switch to only single dose vials. However, this would require a huge increase in the amount of cold storage space required to store the vaccines as well as increased logistical costs across the board (factors that the vast majority of nations can not easily accommodate).

And now, the important stuff.

Is thiomersal the same as methyl mercury?

No, there are several forms of mercury occurring in the environment, however by far the most common organic mercury compound is methyl mercury. The main hazard for methyl mercury is its ability to accumulate in the body and to remain there for a long time. The exposure to this naturally-occurring compound and its toxic effects on humans have been well studied. As most humans are exposed to mercury in some form, WHO and some national regulatory authorities defined safe levels for exposure to mercury and the values reflect exposure mainly to methyl mercury. Thiomersal contains a different form of mercury i.e. ethyl mercury which does not accumulate and is metabolized and removed from the body much faster than is methyl mercury.

Why are some countries withdrawing thiomersal if there is no risk?

Some national public health authorities are striving to replace thiomersal-containing vaccines as a precautionary measure. There is currently no evidence of toxicity from mercury contained in vaccines. There are only a few tested, efficacious and safe alternatives to thiomersal-containing vaccines. Current production capacity for such vaccines is limited and insufficient to cover global needs.

First of all, methyl mercury verses ethyl mercury.

I had not previously heard of the dual mercury terms,  just “mercury” (along with its status as a horrible biomagnifier, and advice to limit my fish intake on account to it). I also suspect that this is where a lot of the vaccine fears stem from.

But moving on, methyl mercury is bad. To borrow from the USGS (link above):

Methylmercury – “Methylmercury (MeHg), one organic form of Hg, can accumulate up the food chain in aquatic systems and lead to high concentrations of MeHg in predatory fish, which, when consumed by humans, can result in an increased risk of adverse effects in highly exposed or sensitive populations. Consumption of contaminated fish is the major source of human exposure to MeHg in the United States.” – National Research Council, 2000

As for eythyl mercury, most sources refer to it as thimerosal. And all for the most part say the same thing.

The CDC:

Is thimerosal safe for people?

  • Yes. Thimerosal has been used safely in vaccines for a long time (since the 1930s) and has a proven track record of being safe. A variety of scientists have been studying the use of vaccines that have thimerosal in them for many years. They haven’t found any actual evidence that thimerosal causes harm.

Why was thimerosal removed from vaccines given to children?

  • Although no evidence suggests that there are safety concerns with thimerosal, vaccine manufacturers have stopped using it as a precautionary measure.The only vaccine that still includes thimerosal as a preservative is the multi-dose inactivated influenza vaccine. There are other formulations of flu vaccine that do not include thimerosal.
  • In 1999, the Food and Drug Administration (FDA) was required by law to assess the amount of mercury in all the products the agency oversees, not just vaccines. The U.S. Public Health Service decided that as much mercury as possible should be removed from vaccines, and thimerosal was the only source of mercury in vaccines.
  • The decision to remove it was a made as a precautionary measure to decrease overall exposure to mercury among young infants.
  • Thimerosal was removed from all childhood vaccines in 2001 with the exception of inactivated flu vaccine in multi-dose vials. However, thimerosal has been removed from all single-dose preparations of flu vaccine for children and adults. There has never been thimerosal in live attenuated flu vaccine or recombinant flu vaccine. No acceptable alternative preservative has yet been identified for multi-dose flu vaccine vials.

From the NIH, there are 2 pages of interest. First is an overview of a study preformed with monkeys:

Since the 1930s, vaccines have contained thimerosal, a mercury-based preservative that breaks down to ethylmercury and thiosalicylate in the body. By some calculations, children given the usual schedule of vaccines containing thimerosal receive ethylmercury in doses exceeding the U.S. Environmental Protection Agency’s guidelines for methylmercury, a known neurotoxicant. Because of the lack of pharmacokinetic and toxicity data for ethylmercury, methylmercury has been used as a reference for ethylmercury toxicity based on the assumption that the two compounds share similar toxicokinetic profiles. However, a new animal study shows that methylmercury is an inadequate reference for ethylmercury due to significant differences in tissue distribution, clearance rates, and ratios of organic to inorganic mercury in the brain [EHP 113:1015–1021].

Though I recommend the readers of this post to follow all links I make (always in these types of posts! One should never take a non-expert of ANY subject at face value!), I highly recommend following up this one. It goes in depth, and shows the risks in equating the 2 types of mercury as one and the same.

And because it may come up, you will also find what follows in the above link:

The researchers emphasize, however, that the risks associated with low-level exposures to inorganic mercury in the developing brain are unknown, and they describe other research linking persistent inorganic mercury exposure with increased activation of microglia in the brain, an effect recently reported in children with autism. They recommend further research focused specifically on the biotransformation of thimerosal and its neurotoxic potential.

Note that this is not confirmation. It is just an admission that there is a lack of data, and a recommendation of further study to fill in the blank. No data is not negative data.

The NIH also has this out on the toxicity of ethyl mercury:

Ethylmercury (etHg) is derived from the metabolism of thimerosal (o-carboxyphenyl-thio-ethyl-sodium salt), which is the most widely used form of organic mercury. Because of its application as a vaccine preservative, almost every human and animal (domestic and farmed) that has been immunized with thimerosal-containing vaccines has been exposed to etHg. Although methylmercury (meHg) is considered a hazardous substance that is to be avoided even at small levels when consumed in foods such as seafood and rice (in Asia), the World Health Organization considers small doses of thimerosal safe regardless of multiple/repetitive exposures to vaccines that are predominantly taken during pregnancy or infancy.

EtHg’s toxicity profile is different from that of meHg, leading to different exposure and toxicity risks. Therefore, in real-life scenarios, a simultaneous exposure to both etHg and meHg might result in enhanced neurotoxic effects in developing mammals. However, our knowledge on this subject is still incomplete, and studies are required to address the predictability of the additive or synergic toxicological effects of etHg and meHg (or other neurotoxicants).

Again, note “knowledge is incomplete”, NOT “ethyl mercury is a proven intoxicant”.

And now, the EPA (a PDF):

It has been suggested that there may be neurological effects of ethylmercury exposure from use of thimerosal in vaccines, though studies have reported conflicting results (21-26). Ethylmercury exposure from thimerosal in some vaccines has been associated, in some studies (27-33) and not others (34-40), with autism and other neurological disorders in children. Several scientific and public policy review committees carefully evaluated the data and concluded that there was not sufficient evidence of a link between autism and thimerosal in vaccines (10, 23, 24, 41). In fact, the Institute of Medicine’s 2004 evaluation included an even stronger statement that rejected the idea that thimerosal-containing vaccines cause autism, concluding that “…epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism” (16, 24). Weighing available information with public health concerns, the American Academy of Pediatrics and the U.S. Public Health Service recommended that thimerosal be phased out of vaccines beginning in 1999 (23) (see Considerations for Decision-Makers in this Chemical Summary). Currently all routinely recommended vaccines for infants in the U.S. (except for inactivated influenza flu vaccines) are available as thimerosal-free preparations, or contain trace (very small) amounts of thimerosal (less than 1 μg mercury/dose)

Note that the cited link above was in the EPA’s PDF.

So, from this little exercise, I have learned a few things.

That there are 2 different types of mercury, not just one “Evil” substance as I was previously led to believe (note that Robert Kennedy failed to make note of that). There is a difference in how the human body deals with both types of mercury, so viewing them as having the same effects is flat out wrong.

One thing I can not say I did was entirely refute Robert Kennedy’s whole argument (in terms of all concerns noted in the interview). I did the best I could, utilizing only the various alphabetical agencies of the US Government and the World Health Organization as sources.

But Kennedy has in the interview made the claim that the vaccine industry has bought off the CDC. While that is a claim that should be taken into consideration, it is a quite extraordinary claim, requiring extraordinary evidence to back it up (to borrow the language of an Atheist). Without the evidence, it is nothing more then conspiratorial assertion.

As interesting as the conversation with Bill was to listen to, he did not provide the evidence. And I suspect Bill knew it to.

Dammit Bill. Your already falsely perceived as an anti-vaxxer due to your unorthodox views on the subject. This interview certainly is not going to help with that image.

Yes, your progressive liberal detractors often make false assumptions based on misunderstandings of your positions. But interviews like this, only makes it worse! Even I was scratching my head!

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