Vaccines, mercury and you

It is often claimed by anti-​​vaccinationists that many, if not all, vaccines contain mercury, and this is a primary reason why vaccines are bad for you and your children. But is this actually true?

Do vaccines really contain mercury? How much mercury? Which vaccines? How does this potential source of mercury exposure compare to other sources of mercury in the environment? Let’s find out.

When people say that vaccines “contain mercury”, what they’re actually referring to is the compound thiomersal, an organic mercury compound used as a bacteriostatic preservative. But do vaccines in use today, particularly those vaccines for pediatric use, actually contain thiomersal?

To answer this question, we need credible primary source information, not just the vague and mendacious claims of anti-​​vaccination groups, which lack any credible evidence. So I examined the original product information sheets for all the vaccines produced by two major vaccine manufacturers; using the list of products from CSL here and the list of vaccines sold in the United States by GlaxoSmithKline, here.

Of those 27 different vaccines, only 3 contain any thiomersal; specifically, CSL’s Q-​​Fever vaccine and GSK’s Fluvarix and FluLaval influenza vaccines. Not a single one of the 24 other vaccines on the market from those two manufacturers contains any thiomersal.

It should be noted that all of those three vaccines are intended for adults; they are not intended, nor are they medically indicated, for any pediatric use. There is not one single vaccine marketed by either of these companies, in the United States at least, which contains any thiomersal in a vaccine intended for pediatric use. Furthermore, the Q-​​Fever vaccine is not administered to the general public at all; it is only administered to people working with livestock who are at a significant risk of contracting Q-​​fever, which is an exotic disease associated with livestock.

So, how much mercury do these vaccines contain?

The FluLaval vaccine contains 25 micrograms of mercury per dose. Since thiomersal is about 50% mercury by mass*, that corresponds to approximately 50 mcg of thiomersal per dose of vaccine. The Q-​​Vax vaccine contains 0.01% thiomersal, or approximately 50 mcg thiomersal in a 0.5 ml dose of vaccine, so that’s similar. The Fluarix vaccine, on the other hand, contains only the slightest trace of residual thiomersal, less than one microgram of mercury equivalent per dose, which is insignificant by comparison.

(* Each thiomersal molecule contains only one mercury atom. But since a mercury atom has quite a large mass compared to other elements present, such as carbon, hydrogen or sulfur, it works out to be approximately 50% of the molecular mass.)

But suppose you get exposed to 25 mcg of mercury per year, from an annual flu vaccine for example. How does that 25 micrograms of mercury compare to mercury you might be exposed to from other sources?

The typical concentration of mercury in most fish is typically around 0.20 parts per million. Generally, fish with a mercury content exceeding 0.50 ppm are regarded as high-​​mercury fish. For some predatory fish at the top of the food chain, such as shark and swordfish, mercury concentrations as high as 1 ppm are not atypical, due to biomagnification of the mercury up the food chain.

If you eat a fish containing 0.20 ppm mercury, you only need to eat 125 g in order to have 25 mcg of mercury intake; the equivalent of a dose of thiomersal-​​containing vaccine. Personally, I think that’s a pretty small dinner. For a fish with 1 ppm mercury concentration, only 25 grams of fish needs to be eaten.

Eye drops and contact lens solutions often contain thiomersal, where it is used as a preservative, just as in the vaccines, in order to inhibit the growth of microorganisms. The bottle of eye drops I have here contains 0.01 mg/​ml of thiomersal, meaning that 5 ml of solution corresponds to 25 mcg of mercury. If you use such eye drops reasonably frequently, you can probably accumulate a vaccination worth of mercury dose relatively quickly.

Now, many of you may have seen this stuff before:

This is mercurochrome, aka. merbromin, a topical antiseptic. Back when I was in early primary school, the school staff would always slather this distinctive bright red dye on our frequent schoolyard grazes and scrapes.

This antibacterial agent, too, like thiomersal, is an organomercury compound, containing approximately 25% Hg per mass. Therefore, a 2% solution, which is usually what the antiseptic solutions are, contains 0.5% mercury, or 25 mcg of mercury in approximately 0.005 ml of solution. You need only apply 5 microlitres, an astonishingly small quantity, of this solution to an open cut or graze to have an effect that is presumably comparable to a thiomersal-​​containing flu vaccine dose. And we had this stuff being slathered on all the time, with no ill effects.

Finally, coal in Australia typically contains around 0.04 mg/​kg of mercury, on average. When the coal is burned, the volatile mercury goes up the chimney in the form of mercury vapor and is released into the environment, where it can be converted into methylmercury by microorganisms and biomagnified in food chains. Coal-​​fired power stations are in fact the largest source of mercury pollution in the environment. The Eraring coal-​​fired power station in New South Wales, for example, burned 6,591,738 tonnes of coal in 2007. Assuming 0.04 mg/​kg of mercury in the coal; that’s 264 kilograms of mercury emitted to the environment from one power station in one year; assuming that the mercury vapor cannot be removed from the exhaust of the power station.

That’s enough mercury emitted in one year, if you imagine that it all found its way into people via the food chain, to deliver a 25 mcg mercury dose to every person on the planet approximately 1.5 times over. Astonishing, huh?

In conclusion, I think it’s pretty clear that in context, a dose of 25 micrograms of mercury from a vaccine, in those infrequent examples of vaccines that really do honestly contain thiomersal, is not a significant health concern, particularly when compared to other sources of mercury exposure.