Friday, February 6, 2015

Vaccine Talk: The Dose Makes the Poison, Part 1

A little over the top, perhaps?
I know it seems like a dramatic departure from the usual topics on this blog, but vaccines are something I'm very passionate about. Considering how relevant their discussion seems to be with this latest Measles outbreak, I figured it might be time to put to rest a number of myths about vaccines. No, I'm not going to talk about how they don't cause autism, because they don't. No, in fact, I'm going to beat a horse that's slightly less dead: anti-vaccine talking up a storm about how vaccines are loaded with "toxins" like formaldehyde and mercury. Unfortunately, what most of these people don't seem to understand is the simple pharmacological concept that the dose makes the poison. Surely you wouldn't slap a banana out of someone's hand because it has potassium in it and that's what lethal injections contain, would you?

In any case, let's begin. This is not an exhaustive list by any means, but I'm going to break down the most common so-called toxins for starters. 

Formaldehyde: Typical anti-vaxxers will point out that this is in embalming fluid and nail polish remover. Gross, right? Well, yeah, kind of, but it's also in things like apples, pears, and milk. And did you also know that when you drink fruit juices, your own body breaks them down into formaldehyde? Bet you didn't know that. I also bet you didn't know that formaldehyde is important in the formation of DNA and amino acids. The key here, again, is that the amount a kid would get from a trip to the doctor's office to get shots is incredibly small and is metabolized within hours:
"At their 6 month visit (when they are, on average, 16.5lbs or 7.5kg) with HepB, DTaP, IPV and flu, for a total of 307.5μg. That is about 160 times less than the total amount their body naturally produces every single day. Compare that to the 428.4-1,516.4μg of formaldehyde in a single apple."
Some people might say, well, if it's natural in an apple, that's different than being made in a lab. No, it's not. Two hydrogen atoms, a carbon, and an oxygen. On a more practical level, the formaldehyde actually has a purpose in vaccines: it is used to deactivate the bacterium in the vaccine so your body can form antibodies against it more easily.

Thimerosal: This is it, the big one. Mercury. Leaving aside that it is no longer in any vaccines except for certain seasonal flu shots, this used to be the major bogeyman of the anti-vax movement, with people insisting that it caused autism (which it doesn't). On some level, I suppose it would be understandable. After all, mercury is toxic to humans. However, not all mercury molecules are created equal. Methyl mercury, which is in things like tuna and those old-school glass thermometers, is the kind of mercury that usually comes to mind. It does accumulate in the body and is toxic to humans. 

By contrast, thimerosal, which contains ethyl mercury, does not accumulate in the body and is metabolized by the body much more quickly (in a matter of days). Not to mention, of course, that if you eat a can of tuna every once in awhile, you're getting about the same amount of methyl mercury as you would ethyl mercury in a vaccine, with the added detriment of bioaccumulation. Thimerosal was/is used as a preservative, so that multiple vaccine doses could be drawn from the same vial (for cost-effectiveness) and would not require refrigeration. This may not be an issue for us here in the U.S., but in poorer countries, where reliable refrigeration and costs matter more, this made vaccines more expensive and thus harder to get.

Aluminum: The new boogeyman, mercury's successor, etc. Aluminum is used as an adjuvant, which means that it basically provokes the body's immune response in order for it to properly form antibodies for the disease. Seems kind of important for vaccines to work, right? Not only is it important, but again, the dose makes the poison in this case. Anti-vaxxers point out that aluminum has been associated with breast cancer and Alzheimer's Disease. Not only are these claims dubious, at best, but the levels of aluminum in each shot are extremely low

For example: the aluminum content in vaccines ranges from 0.125 mg/dose to 0.85 mg/dose. By contrast, infant formula contains 0.225 mg/liter, and aspirin contains 10-20 mg/tablet. Put more clearly, the average adult takes in about 7-9 milligrams of aluminum per day. The average baby gets about 4.4 mg of aluminum from vaccines in the first 6 months of life. Over that same period, an infant receives 7 mg of aluminum over the same period from breast milk alone. Who knew that breast-feeding caused breast cancer, right? You're beginning to get the picture.

So there you have it, those are the three biggest "toxins" you hear about from the anti-vaccine crowd. There are plenty more for me to run through, but I'll spread them over a number of blog posts so we both don't get burnt out. Hopefully the next time you read about these toxins, just remember, the dose makes the poison.