Fortunately, recent research into thimerosal has not found any links between neurological disorders and the doses of ethylmercury found in vaccines. One specific concern was that thimerosal exposure might increase the risk of developing autism. However, population studies did not show any change in the rate of autistic spectrum disorders after thimerosal was removed from vaccines in Denmark and Sweden in 1992.
Another study evaluated over a thousand children with a battery of forty-two neuropsychological tests. These tests were administered to the children seven to ten years after their thimerosal exposure. The results were surprising. Only a few tests showed some relation to ethylmercury, but the results were almost equally divided between positive and negative results. This means that while a very few (less than 3 percent) of the tests showed that thimerosal hindered a neuropsychological skill, the same number of tests showed that thimerosal improved a similar skill. In the end, the random nature of these results, plus the majority of normal results, suggested that the noted associations were most likely due to chance.
Another study investigated the elimination of ethylmercury and methylmercury from the bodies of infant monkeys. It found that ethylmercury is eliminated from the body three to ten times faster than methylmercury, suggesting that ethylmercury is much less toxic than methylmercury.
In conclusion, multiple studies have not shown any relation between thimerosal and autism or other neuropsychological disorders.