Autism has become more prevalent in the past 20 years, as have early childhood vaccinations. Seeking an answer for the increase in autistic children, many people have began to blame vaccinations as the primary cause. Is this justified? Well, thimerosal, which is a mercury-based preservative, was used in childhood vaccinations up until about a decade ago (however, it is still used in the Flu shot). And there have been associations of high mercury levels in autistic children, a possible link to the vaccination theory. However, as of yet, no research has proven vaccinations as a cause of Autism. The higher mercury levels may be due to the inability to process metal as efficiently as non-autistic children because of biochemical defects. Additionally, testosterone has been shown to affect mercury levels, and most autistic children are males. So why are people still so convinced that vaccinations cause Autism? Children get vaccinated around the same time that a child with Autism would begin to show symptoms. Parents need an explanation for what is happening to their children, yet there have been no definitive causes of Autism, so they just associate the onset of Autism with the most recent change in their child's life, vaccinations. Until further, definitive research is discovered, the debate about Autism and vaccines will continue.
For more information, check out this article in The New York Times.