Another Study Finding No Link Between Mercury and Autism
Mercury, the bane of many a mad hatter of yore, has been the focus of many in the autism community as a potential cause of autism. The heavy liquid metal is well known for it's toxic effect, causing aggressiveness, mood swings, and anti-social behavior. It was used during the 19th century in the making of hats, and those Hatters that had too much exposure would become "mad", hence the term "mad as a hatter". The similarity of the symptoms to autism, and the revelation of the use of thimerosal, a compound that uses mercury, as a preservative for vaccinations that were injected at about 2 years old when autism behaviors were becoming evident created a correlation that many people associated with cause.
The correlation seemed to be pretty clear, and it sparked a wave of fear against vaccinations and to a lesser extent mercury. So, in order to test the theory that mercury is causing autism, the largest long-term study of it's kind was started in 1983 by the University of Rochester Medical Center: The Seychelles Child Development Study as reported by Forbes.
Why the Seychelles? Because in this nation of islands north of Madagascar, the people eat a lot of fish. And when I say a lot of fish, I mean 10 to 20 times more fish than the average American or European might consume.
And why is fish consumption relevant? Fish caught for consumption eat smaller fish, who in turn eat smaller fish, and so on until you get to the plankton who are consuming whatever they can, and that includes methylmercury. Methylmercury is a compound of mercury that is released by volcanoes, coal burning power plants, and mining. This source of mercury builds up in a fish's system as it consumes within the chain, slowly building up the levels of methylmercury within the predatory fish. So when we eat the predatory fish, we consume low levels of mercury. In the Seychelles, people consume 20 times the methylmercury than in the United States.
With this extreme, using the US and Europe as a control, the University of Rochester would try to identify whether or not increased mercury exposure during development would cause autism-like behaviors. They would use maternal hair samples to identify the level of mercury in the mother's system when they gave birth, and then evaluated the children over a period of 30 years. The evaluations were surveys filled out by parents to map child behavior, much as the same that's used today in evaluating for autism.
The results were definitive, in that there were beneficial associations of prenatal methylmercury exposure with developmental outcomes, as opposed to negative effects expected, though the study does suggest it could have been caused by the beneficial compounds found in fish (such as Omega 3 fatty acids and the like).
So what does this have to do with mercury in vaccines? The amount of mercury in thimerosal is much lower than the mercury found in one serving of canned tuna fish. If such (relatively) high levels of methylmercury consumed in the Seychelles doesn't cause autism, then the comparatively minute amounts of mercury in thimerosal wouldn't cause it.
So where does this leave us? Hopefully, it leaves us with the understanding that mercury is not the "cause", that we have exhausted this avenue of research and can focus on more promising avenues. It should also leave us with a clear understanding in science: correlation does NOT mean causation. And this study has been well done, conducted by an American university, not bankrolled by the fish industry, or a conspiracy perpetrated by big pharm. This is good research conducted over decades that has shown us that fish is safe to consume when expecting a child, and throughout the child's life.