argh! the dreaded mercury!

One of my commenters asked the following question, & while I answered it quickly in that thread, I thought it might be useful for her (& maybe others) if I found a few references to support what I said.

One of my friends has this as their current status on Facebook, and I wondered if you had some facts at your fingertips which I could steal to reply (as I’m sure it’s not scientifically sound):

"the swine flu itself has killed about 2-3,000 people total. The regular flue kills 40,000+ per year. The vaccine contains 2 dangerous compounds, one is thimerosol. It is made 50% of mercury. It binds to receptors in your brain, and can cause brain damage. The other is squalene. It accidentally tricks your immune system into killing your own cells. So people, what do we think?"

Just as an aside, I’d say your friend is using information from an anti-vaccination site, since I’ve seen the same wording elsewhere (in the comments thread at this link). You could maybe ask her to provide hard evidence in support of those statements… But anyway –  it’s true to say that (so far) H1N1 influenza hasn’t killed as many people as the ‘normal’ seasonal flu. Worryingly, however, those it kills tend to be young, while it’s more likely to be the elderly who are affected by the seasonal variety. In addition, the northern hemisphere is going into its second winter with H1N1 circulating in the population, & there are signifcant concerns that the virus will be more virulent second time around. Hence the mass vaccination campaing currently underway in the US.

Thimerosal. Aaahh, thimerosal. Thimerosal is a mercury compound, which used to be widely used as a preservative in vaccines. However, it was phased out of childhood vaccines early this century, although it’s still found in some adult vaccines – including H1N1, although this vaccine is also available without thimerosal. One of the reasons for that phasing-out was the widespread (but erroneous) belief in some quarters that thimerosal was the cause of an ‘autism epidemic’ – yet there has been no decline in the rate of autism diagnoses since then, which would tend to indicate that there’s no causal link. Thimerosal – also known as ethyl mercury – is present in very low doses in vaccines – in the case of the H1N1 vaccine, at a concentration of 0.01%. This is the same as 1 in 10,000, & since thimerosal is roughly 50% mercury by weight, a 1-in-10,000 concentration contains around 25 micrograms of mercury per 0.5mL. Unlike methyl mercury, ethyl mercury doesn’t bioaccumulate & is excreted from the body. There is no evidence of any link between thimerosal/ethyl mercury and any form of brain damage/disorder (including autism): Orac has written very extensively on this.

You can buy squalene commercially – in this form it’s derived from sharks & people apparently take it as a dietary supplement. (I wonder if they realise the damage they could be doing to themselves? Oh dear!). It’s also produced in your body as a part of normal metabolic processes (including synthesis of cholesterol), it’s found in olive oil, & it’s present in some vaccines as an adjuvant – something which enhances the vaccine’s ability to stimulate an immune response (some antigens used in vaccines don’t elicit a sufficiently strong immune response without an adjuvant also being present).  Those opposing the use of squalene claim that it stimulates the production of anti-squalene antibodies, which will then go on to attack & destroy squalene wherever it’s found in the body, causing all sorts of nasty illnesses including ‘Gulf War syndrome’ – a claim which (again) is not borne out by well-designed & performed scientific studies.

The trouble with claims like those I’ve looked at there is that there’s a risk that people will be put off vaccinating their children (or themselves) as a result of this scare-mongering. And this is bad for the population at large. Not everyone reacts strongly to a given vaccine – I’ve never produced any lasting high levels of antibodies to rubella, for example, despite getting vaccinated before attempting to get pregnant. Children who are too young to be vaccinated rely on the herd immunity generated by having a high rate of vaccination in the population at large, as do those who are immuno-compromised for some reason (those undergoing chemotherapy, for example, or recipients of organ transplants).

So, Renee, I hope you can persuade your friend to reconsider her stance on this one!