The controversy surrounding the use of thimerosal, best known for its use as an ethylmercury-based preservative found in infant vaccines and pregnancy shots, to autism and other developmental disorders has led many families to question whether the potential risks associated with early childhood immunizations may outweigh the benefits.

Yet according to a news release issued by the National Autism Association, a study posted in Environmental Health Perspectives (EHP) appeared to diminish the damage thimerosal can have on children.

Primate Study

The study involved some 40 monkeys who were fed either methylmercury or given shots of thimerosal in doses comparable to those given in vaccines to human infants. It was found that the ethylmercury contained in thimerosal was cleared quickly by the body, while methylmercury -- widely hailed at the worse of the two -- persisted much longer.

What does this really mean? Ethylmercury was much more damaging because it crossed the blood-brain barrier more quickly than methylmercury.

Deceptively, EHP framed the results in a misleading, positive light. To say that ethylmercury clears the blood faster and is therefore less toxic than methylmercury is dishonest by means of omission -- attempting to deflect attention from the frightening fact that ethylmercury makes its way to the brain much faster than methylmercury and can be trapped there for years.

The Frightening Reality

• Much higher amounts of inorganic mercury was found in the brains of infants injected with thimerosal than those with methylmercury (up to 71 percent vs. 10 percent).

• Infants' brains exposed to thimerosal contained at least twice the amount of inorganic mercury as those tainted by methylmercury.

PharmaLive April 21, 2005

Environmental Health Perspectives April 21, 2005 (Free Full-Text Article)

Wired April 21, 2005

The Tri-Valley Herald April 21, 2005