The controversy regarding the once widely used mercury-containing preservative thimerosal in childhood vaccines has raised many historical questions that have not been adequately explored.
As some people continue to deny that there is a link between autism spectrum disorder and mercury, new studies have now been added to the growing pile of evidence illustrating just how wrong they are.
Mercury is toxic to the human body. It's important, however, to understand how the mercury present in immunizations is different than the mercury in, say, the scary old thermometer in your medicine cabinet. Mercury is a potent neurotoxin. Even the smallest amounts can cause cumulative adverse effects. Two of the most widespread forms of mercury exposure come from the organic compounds methylmercury (found in fish) and ethylmercury, which makes up 50% of the vaccine preservative thimerosal. Mercury is capable of crossing the blood-brain barrier, and it is believed to raise the risk of neurodevelopmental disorders like tics, attention-deficit/hyperactivity disorder, and speech delays in addition to autism spectrum disorder.
According to review published in Journal of Trace Elements in Medicine and Biology majority (74%) suggest that mercury is a risk factor for ASD, revealing both direct and indirect effects. In another study published in Neuro Endocrinol Lett. States that it was found that autistic children had a higher mercury exposure during pregnancy due to maternal dental amalgam and thimerosal-containing immunoglobulin shots. It was hypothesized that children with autism have a decreased detoxification capacity due to genetic polymorphism.
The international journal Science of the Total Environment has just published a compelling study from the Republic of Korea, where autism prevalence is high. The study identifies a strong relationship between prenatal and early childhood exposure to mercury and autistic behaviors in five-year-olds.
Most of this mercury came from the mothers. The main sources of exposure mercury amalgam fillings, Rho D immunoglobulin injections containing thimerosal given to Rhesus negative mothers, and heavy consumption of fish (defined as more than five fish meals a month).