This article deals with the issue of thimerosal, which is a antibacterial used in flu vaccines. Although thimerosal is being phased out of many vaccines in the U.S. and Europe, its continued controversial use in flu vaccines may have implications for the success of vaccination efforts.

[Opinion - ed.]

Personal Preface

When I was a preschooler, I got the usual round of childhood vaccinations. Back in those days, thimerosal was used as an antibacterial in most of them. I’m still here. A case can be made for the proposition that I’m even in my right mind.

I’ve never been a big fan of flu shots. In my case, the issue isn’t thimerosal so much as the egg serum, to which I have reason to believe I am most seriously allergic. The last flu shot I had was during the swine flu business, almost 30 years ago.

The odds I’ll get flu are slim to nil in a “normal” flu year. A weak immune system is not one of my problems. But the odds the flu shot will make me sick enough to miss work days while in bed feeling like death warmed over are close to unity. Hence, in a “normal” flu year, I just pass.

That being said, if the current NIAID H5N1 vaccine candidate, which entered human safety trials at the end of March, survives said trials and achieves general deployment, my sleeve will be rolled up so fast it will seem to simply disappear. Thimerosal or no thimerosal, egg serum or no egg serum. I’ll just let my boss know that allergies are going to be kicking me from pillar to post for a while.

Basic facts about Thimerosal

Courtesy of Wikipedia

Thimerosal (sometimes spelled as thimerosol and thiomersal [1] (trade name: Merthiolate) is an organometallic compound used commonly since the 1930s as a preservative in some vaccines, cosmetics, tattoo inks, eye drops, and contact lens solutions. Such use has become increasingly controversial in recent years, due to concerns about potential neurotoxic properties of the mercury containing compound.
Its chemical formula is C9H9HgNaO2S. In the body it is metabolized to ethylmercury (C2H5Hg+) and thiosalicylate. Thimerosal has proven to be highly effective against bacterial contamination in multidose containers of vaccinations [2]. Thimerosal causes susceptible bacteria to autolyze (breakdown its own cells with self-produced enzymes via an unknown mechanism.

The Wikipedia article goes on to detail the gargantuan furball that has detonated around the use of thimerosal in vaccines in recent years. I won’t go into that. Ye Gods, we’ve got parents with autistic kids, special interests, professional witnesses, industry reps, and government agencies hurling anecdotal reports, assertions, counter-assertions, charges, countercharges, accusations, and everything but brickbats back and forth. Wading through a mess like that to get to ground zero truth is next to impossible.

Robert Kennedy wrote this piece in, reprinted at commondreams, which added yet more gasoline to the fire.

However, the same assertion keeps coming in via differing lines of report, not all of them American by any means. No causal link between thimerosal and autism has ever yet been shown. The “differing lines of report” business is significant, in my opinion. It heightens the credibility of the assertion. A child by child study of all children born in Denmark between January 1, 1990, and December 31, 1996 showed “no significant difference between the incidence of autism and other such problems in children who received the vaccine with or without thimerosal, and no indications of a dose-response relationship between autism and the amount of ethylmercury received through thimerosal.”

“Previous studies have not looked at personally identifiable data,” Dr Melbye says. “We were able to look at the incidence curve for autism and find no sign that it correlates with thimerosal exposure.”

One immediate consequence of the furball, and not a bad one in the least, is that the use of thimerosal as an antibacterial in vaccines is being phased out across the board. The Johns Hopkins Bloomberg School of Health has prepared a thimerosal content table of 40 different vaccines and vaccine types licensed in the United States. Of these 40, only 9 contain thimerosal, at a concentration of 0.01%. These are as follows.

  • DTwP (Diphtheria & Tetanus Toxoids with Pertussis)
  • DT (Diphtheria & Tetanus Toxoids)
  • Tetanus Toxiod
  • All influenza vaccines except FluMist
  • The Meningitis vaccine MENOMUNE-A/C/Y/W-135

Note from the cited article that thimerosal is conspicuous by its absence in U.S. licensed measles/mumps/rubella (MMR) vaccine. Which makes the results of the study performed in Denmark between 1991 and 1998 no surprise at all, since it dealt only with MMR vaccinations of children. Bottom line: “no difference in incidence of autism between vaccinated and unvaccinated children”.

Frankly, it seems to me that in the Year of Our Lord 2005, we can find alternatives to thimerosal whose risks are better understood.

Note that Canada has abandoned the use of thimerosal in all childhood vaccines.

I will mention, in passing, that EPA standards for acceptable exposure are based on methymercury, not on ethylmercury, which is the mercury-containing breakdown product of thimerosal. The UIC web page, as well as Wikipedia and every other credible source I have been able to unearth, states that ethylmercury toxicity is neither well-studied nor well understood.

The Wikipedia piece does speak to comparison between methylmercury effects and ethylmercury effects.

The latest controversy surrounds a newly-released, NIH-funded primate study [30], [31], conducted by Dr. Thomas Burbacher [32], an associate professor of environmental health and the director of the primate research center at the University of Washington. In his study, the effects of injected ethylmercury were compared with those of orally administered methylmercury in order to ascertain whether methylmercury provided a suitable reference for assessing the effects of ethylmercury found in thimerosal. The study revealed significant differences between methyl- and ethylmercury metabolism.
The injected ethylmercury cleared from the bloodstream much more rapidly than ingested methylmercury. However, the study also found that a larger fraction of the ethylmercury that remained in the primates’ brains was converted to potentially more harmful inorganic compounds. Burbacher did not draw conclusions regarding the relative toxicity of ethylmercury versus methylmercury, but did warn that methylmercury is likely not a suitable reference for evaluating ethylmercury toxicity. In an interview, Burbacher commented
“The bottom line is that trying to assess the effects of a compound with very little or no data is not a good thing to do. … Unfortunately, we started doing studies on this compound way too late. Basic information like this should’ve been available decades ago.”[33]

In other words, comparing methylmercury toxicity with ethylmercury toxicity is like comparing apples and oranges. We know the apple well, but the orange is terra incognita. All we know for sure is that the orange is different.


So where does all this leave us?

First off, I put myself in the shoes of a conscientious physician, extremely mindful of his medical oath, who is crafting vaccine preparation techniques sometime in the first half of the 20′th century.

I have two choices.

  • Permit lots of vaccine to go out which might be contaminated by bacteria.
  • Introduce some antibacterial into the vaccine lots during their creation.

The first choice is completely unthinkable, given any alternative at all. A direct violation of the medical oath, pure and exceedingly simple.

Where to find the antibacterial? Which one to use?

Well, Merthiolate has been used as a topical antibacterial for donkey’s years, by half of the country. On open bleeding wounds, to boot. Impossible to imagine that many many people have not had it literally enter their bloodstreams and systems. It causes bacteria to autolyze. Effective enough.

In my humble opinion, in the absence of contradictory data, thimerosal would have been a rational choice. No need to invoke conspiracy or corporatism; it seems to me that an extremely ethical man could arrive at this choice.

BTW, I suspect that codgers as old as myself remember Merthiolate. Its recent incarnations, however, contain no mercury.

Secondly, vaccines containing thimerosal as an antibacterial are not the only “troubled” vaccines out there.

Routine use of the Dryvax smallpox vaccine ceased in the United States in 1971, for the excellent reason that the risks from routine use of the vaccine were orders of magnitude greater than the risk from smallpox, which had in fact been extinct in the U.S. for more than a decade.

Routine use of the Sabin vaccine, which stamped out polio in the U.S. like a cockroach, was discontinued in 2000. Why? It causes polio in one out of 2.4 million recipients.

Note that in both of these cases, discontinuation of an admittedly flawed vaccine was preceded by elimination of the disease threat that made its initial deployment necessary.

Unfortunately, we are not on the descending part of the curve with H5N1. The storm has yet to hit. To my way of thinking, that makes thimerosal, which with near certainly will be part of any H5N1 vaccine deployed in the near future, an inevitable evil. One whose risks are poorly understood, but which are almost certainly many orders of magnitude below those of the virus now brewing up in Southeast Asia.

Page last modified on August 07, 2005, at 01:04 PM by kaspit