4: There's Mercury In Vaccines

Well, it's always good to start with a fact on your side. Actually it's a little more complex than that: there's some mercury in some vaccines. In case you didn't know the details, mercury accumulates in the body because we lack a mechanism for removing it, a phenomenon called "bioaccumulation." It causes neurological symptoms similar to lead poisoning. Yes, mercury is something you don't want. But the mercury in some vaccines is in the form of  thiomersal, which is a salt. Salts are chemically and electrically neutral, pH-neutral combinations of an acid and an alkali, usually involving a metal. It's the name for a class of substances, but it's common table salt in most people's minds. Table salt is made of sodium, a metal so volatile that it has to be stored in oil to prevent it exploding on contact with moist air, and chlorine, a lethal poison that's also horribly caustic, causing chemical burns to skin and eyes.

When you put them together you get table salt, which is neither explosive nor poisonous. So is it the same story with thiomersal?

The anti-vaxxxers want to have it both ways here. On the one hand, they want thiomersal to be bad because it contains mercury. On the other hand, they want the way to remove mercury from the body to be chelation therapy, which involves binding dangerous heavy metals to a reactive chemical partner to make them metabolically discoverable so the body can flush them out. Mercury salts are bad, except when you make them by chelation; then they're good. But mercury salts aren't metabolized inside the body, and as we've seen, salts don't have the chemical properties of their chemical constituents. (It's also worth pointing out that chelation therapy only works for certain types of mercury. If you've been exposed to metallic mercury fumes, chelation is for you. If you've eaten too much tuna or otherwise been exposed to "biomercury" then it's not.)

So is there any health risk associated with thiomersal?

The truth is, it's hard to say for certain. That doesn't mean, "Aha! So they admit it's a deadly poison and then try to use weasel words to get out of it!" It means, thiomersal toxicity is not understood very well. There are two types of mercury, ethyl and methyl, and they react differently to all sorts of things, including being inside you. So it's not easy to be clear about the dangers of the ethylymercury in thiomersal when most toxicity research has been on methylmercury. We do know it doesn't bioaccumulate in the same way. To be on the safe side, and despite a scientific review by the IOM and 9 studies by the CDC clearly showing that there's no link between thiomersal and autism, the CDC pulled it from the majority of vaccines as a precautionary measure.

READ Why Parents Should Still Say Yes To Childhood Vaccines

The general picture looks like this, though: If there was as much thiomersal in every single childhood vaccine as there is in the most thiomersal-rich of modern vaccines, the Fluzone vaccine, then by eleven, that child would have absorbed 0.55 milligrams of ethylmercury. How dangerous is that, exactly? In the medical literature there are records of experiments with thiomersal which show acute mercury toxicity symptoms, but those were in cases of acute (short term) exposure to quantities of thiomersal ranging from 3mg per kilo bodyweight (c. 1.4mg per pound) to "several hundred mg/kg," meaning the average adult man (who weighs 195 pounds) would have been exposed to around 300mg of thiomersal or more: at least 600 times the amount a child would be exposed to over more than ten years if every vaccine contained a high thiomersal dose like Fluzone.

There's some evidence that thimerasol can yield metallic mercury in aqueous solution (dissolved in water) and that this can damage mitochondrial DNA. The study also argues that mercury tends to build up inside cells as lipophillic (fat, attracted) cations (electrically charged particles). Thus, the authors state, mercury levels inside cells may be up to 1000 times higher than in the body as a whole. That's obviously bad, but there are several things we should note. First, the study authors pointed out that their findings "may be clinically relevant in the setting of a patient who harbors a known or unknown mitochondrial disorder" since "in the setting of a mitochondrial disorder, a specific mitochondrial toxin could be life altering or life threatening." Also, it's a lab experiment carried out on grown tissues, not on living animals or people, where effects can be different. 

Obviously the ideal amount of mercury to be exposed to would be zero. But thimerosal doesn't look that dangerous ranged against other toxic heavy metal exposures. It's been removed from the majority of vaccines worldwide and is now found mainly in flu vaccines. If you took the flu vaccine every year like clockwork your whole adult life, you'd wind up exposed to 1.6mg of mercury, in total. By comparison, the average US adult is walking around with a blood lead level two orders of magnitude higher than a natural, baseline level.