Thimerosal Is a Salt, and It’s Pretty Safe

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.

Effects of ethanol… Drunkedness.
Effects of methanol… Blindness.

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.

I'm a doctoral candidate in the Doctor of Public Health program at the Johns Hopkins University Bloomberg School of Public Health. All opinions posted here are my own, of course, and they do not necessarily reflect the opinions of my school, employers, friends, family, etc. Feel free to follow me on Twitter: @EpiRen

3 thoughts on “Thimerosal Is a Salt, and It’s Pretty Safe

  1. Well, chlorine is a deadly gas that killed many people in WWI, obviously NaCl, good old salt is also bad.
    Or something.

    Although, for thoroughness sake, I did look up the LD50 for thimerosal, which is 75mg/kg. That’s not especially potent, especially when in use in a vaccine vial, it’s present in *microgram* levels and one’s only going to be getting milligrams of injection, to a gram or so, depending upon how many CC’s one is receiving (let’s face it, every drug and vaccine that’s injected is mostly water and 1CC is 1 gram at STP (OK, it’s slightly more complicated than that, with today’s precision, but that was the basis for the metric system and it’s close enough for real macro sized life).
    But, that matters not to the folks who are crazy fearful of chemicals, only to shoot MMS up their kid’s butt.
    Yeah, that makes no damned sense to me either.
    Which is saying something, as I’m quite the fan of MMS in civil water supply purification. Hell, if I could get technical in a decent quantity, I’d use it in the swimming pool, I don’t because I don’t want the hazmat problems involved if there’s a spill and I’m *very* close to a waterway. So, while I could acquire it, I can’t store it as safely as I’d prefer would be the more accurate way of saying that.

    Still, we did recently have a mass death event in this state recently, due to an overdose of hydroxic acid. It was quite literally raining the crap.
    Yeah, it rained a *lot*, a bunch of people drowned.

    Oh, a bit of trivia. What is one of the earliest successful treatments for methanol poisoning?
    Ethanol. It competes in the liver, allowing the methanol to be more slowly and hence, safely eliminated.
    Rather ironic, as the reason most people drank methanol was because they couldn’t afford the more expensive (and taxed) ethanol.

    Oh, major win with my wife’s osteoporosis, the insurance company finally blessed her receiving her infusions so that she’ll not dissolve so much bone.
    A setback, recent glucose crashes. I think it’s time to dial back the Lantus a bit.
    To complicate a differential, her liver isn’t functioning all that well, secondary to bilary cirrhosis. To add to complexities, she’s also taking morphine sulfate ER, with hydromorphone immediate release for breakthrough pain, which is a given.
    But, despite doctor also being mystified, a breakthrough there was detecting the glucose crash. Which could easily explain some recent falls, sudden slumping into unconsciousness while sitting, etc.
    Now, add to that, a hint that she passed a renal calculus and she’s been anorexic, which would make sense if one’s in that situation and it’s partially masked by the pain medications.

    Just modeling it in my head, it’s reasonable, not highly uncommon (she’s infamous for passing small calculi and later, throwing a UTI), plausible, I’ll jot off a note to doctor and see what he thinks.


    • I thought they still used ethanol to treat methanol poisoning? I seem to recall my wife telling me a story of when they used it on a patient when she was a student. Then again, I think it was in the backwater country in Montana.


      • I was hoping that you’d tickle onto that.
        Some old treatments don’t go away, as we’ve not found a superior treatment. 🙂
        Even if it’s a lot ironic.

        How to treat a methanol intoxicated alcoholic? Ethanol.
        Well, that, supportive therapy, hydration…


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