I completely understand why chemicals are scary. From the time that we’re kids, we’re told that there are poisons out there, and that those poisons are chemicals. They usually have really complex-sounding names, names we don’t use everyday. So I also understand when people are skeptical of chemicals included or added in food. Remember the whole debacle over Subway having a “yoga mat chemical” in its bread? It turns out that the chemical in question was in more foods than just the bread at Subway, but, because of the actions of a few “food warriors,” we only freak out about a large company using it.
As it turns out, what makes chemicals safe or dangerous is in large part the concentration of the chemical you ingest. Water, a chemical we need to live, can be dangerous in excess. Drink too much water and you dilute the other stuff in your body that you need for energy, nerve transmission, and waste removal. Botulinum toxin, a chemical found in dangerous bacteria that cause botulism, can be given in very small amounts to treat migraines, muscle pain, and for cosmetic reasons. Eat too much sugar at one time and you drive your metabolism into acidosis (where your blood falls too far below the pH of 7.35). Eat too much over your lifetime, and you are likely to become obese and have all the health complications that come with it.
So you get the gist of how this whole thing with chemicals goes.
Now, let’s talk about salts. In chemistry, a salt is a compound that results from an acid-base reaction. Of course, most people think of table salt (sodium chloride) when they hear the world “salt.”
Just the other day, I tweeted out an article about the influenza vaccine. An antivaxxer from Australia who fancies herself a “whistleblower” about vaccine safety, almost immediately replied to me. She told me to be weary of a “hot shot” from a multi-dose vial of influenza vaccine. By that, she meant that thimerosal can concentrate within the vial and I would get a big dose of it. When I pointed out to her that thimerosal is not pure mercury, just like table salt (sodium chloride) is not pure chlorine, she asked a very reasonable question: “Is English your first language?”
Why is it that these antivaxxers always go there with me?
Even Green Party Presidential Candidate, and physician, Dr. Jill Stein uses the “scary mercury” gambit when talking about thimerosal and vaccines:
This was not a “public health win,” by the way.
The reason thimerosal is needed in vaccines is because vaccines are pretty good as a medium on which bacteria can grow. If a vial is not refrigerated well and opened, bacteria could colonize it and produce their own toxins. Then you give the contaminated vaccine to an individual and end up with some pretty bad results. (Last year, in Chiapas, Mexico, several children had to be hospitalized because of bacterial contamination of the vaccines they received. They got them in a rural part of Mexico where refrigeration is not the best.)
To prevent this contamination, thimerosal is added in very, very low concentrations to the vaccine solution. It’s a concentration high enough to kill any bacteria (or at least keep them from growing) that may have fallen into the solution. But the concentration is also low enough to not cause any health problems in a human being. (This ability to kill things in vials is also why thimerosal is not used in the MMR vaccine, a live virus vaccine, contrary to what “MMR CAUSES AUTISM!!!!” people want you to believe.)
But thimerosal has mercury, and mercury is pretty bad, right?
Well, it’s all in the chemistry. The mercury compound that is thimerosal is not the same as the mercury compound that is found in, say, tuna. Just like ethanol and methanol are both alcohols, their effects on the body can be quite different.
So why did we get rid of thimerosal in vaccines? Public relations. That’s all. False accusations of thimerosal causing autism began to manifest themselves in lower vaccination rates. Vaccine manufacturers and vaccine policymakers began to research the possibility of removing thimerosal from vaccines. In the United States, where refrigeration of vaccines is not a big problem, they decided it would be okay to remove thimerosal. It was a public relations win for the antivaxxers since they were now able to say that thimerosal must be dangerous if it was removed.
The problem with this is that other countries — with less-than-perfect cold chain systems for their vaccines — looked at this and asked why they were still using vaccines with thimerosal. They became more afraid of the false threat of autism than the true threat of infectious disease. And we ended up with events like the one in Chiapas happening in other countries where refrigeration is not widely avaibale.
Another problem is that, to the uninitiated, antivaxxers sound reasonable when they point at thimerosal as a boogeyman. After all, if the US Government took it out of vaccines, it must because it’s bad. Then the same uninitiated read what thimerosal is, and they see the word “mercury,” and they think that the mercury in thimerosal is like the mercury that the same US Government and private organizations warn pregnant women about (from eating tuna and other fish).
Then, when I try to begin an explanation of why thimerosal is not bad in vaccines, I get the “YOU’RE A FOREIGNER, YOU DON’T KNOW ANYTHING” card thrown at me. Because, again, this is how antivaxxers play the game. They will not talk to you about how the dose makes the poison, how saying thimerosal is mercury is like saying table salt is chlorine, and they will make baseless accusations based on preconceived notions.
If only there was a thimerosal-containing vaccine for anti-vaccine lies and misinformation.
René F. Najera, DrPH
I'm a Doctor of Public Health, having studied at the Johns Hopkins University Bloomberg School of Public Health.
All opinions are my own and in no way represent anyone else or any of the organizations for which I work.
About History of Vaccines: I am the editor of the History of Vaccines site, a project of the College of Physicians of Philadelphia. Please read the About page on the site for more information.
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