Thursday, June 14, 2012

Quicksilver queries

kw: medicine, alternative medicine, toxins

I saw another news article about mercury in vaccines, and was stunned to read that people are still trying to link autism in. Of course, mercury isn't the first target of anti-vaccine crusaders, it is at least the third. First it was thought that there were measles viruses in the vaccine, and they were causing blood clots that got in the brain and damaged it. When that was shown to be entirely false, the next target was "bad proteins" caused by bodily reactions to the vaccine. When no reactions other than rare allergies actually turned up, mercury, in the form of thimerosal (about 50% mercury as ethylmercury), was claimed to cause autism.

As it happens, there are only two or three vaccines that still contain thimerosal. It has been eliminated from the others (see this table from Johns Hopkins) over the past 20-30 years. Yet all that time, autism rates have continued to go up. Also, among those who decline to vaccinate their children, the autism rate is identical to the rest of the population.

In the aforementioned table from Johns Hopkins, we find that the mercury content in a dose of vaccine (only the ones for tetanus, influenza, and meningitis, and that only from certain suppliers) is 25 micrograms. So if you get a flu shot every year, and the vaccine does contain thimerosal, your mercury exposure is 25 micrograms yearly.

Digging around, I found that my own primary mercury exposure is fish. While we cook fish once in a while, we eat tuna sandwiches a bit more, perhaps every couple of weeks. In a report by Consumer Reports, there were two kinds of tuna tested, several brands each. For white tuna, the mercury content ranged from 0.2 ppm to 0.8 ppm (ppm = parts per million). For light tuna, it was 0.02 ppm to 0.2 ppm. Those sound like small numbers. But how much is a part per million?

One "serving" of canned tuna is shown on the package as 2.5 oz, which is about 70 grams. Thus one part per million would be 70 micrograms. For white tuna, the kind we get, our mercury exposure per serving is thus somewhere between 14 and 56 micrograms. At the high end, it is like getting two vaccinations in one tuna sandwich! Not only that, but 2.5 ounces is a pretty thin sandwich. I typically use about twice that much (go ahead, work out the numbers).

Things are actually better when we cook fish, because we usually have either salmon, whitefish, or tilapia. All these have mercury levels below 0.02 ppm, or 2.8 micrograms per 5-ounce serving. But if we eat cooked fish nine times yearly, our annual mercury exposure would be 25 micrograms, the same as a flu shot. We actually eat fish more often than that, perhaps twice a month.

Let's regroup. I really started talking about autism, which shows up in infants or toddlers. "Ordinary" autism is evident in a newborn. "Late" autism shows up by the third year, sometimes later, but is much less frequent. Few one- or two-year-olds have eaten a lot of tuna sandwiches, and with today's vaccines, they have had zero exposure to thimerosal. If mercury, whether injected or ingested, is causing neurological damage, it's something other than autism, but nobody has put their finger on anything it might be! At the levels mercury is getting into us, it is a cause looking for an effect that has yet to be found.

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