(September 26, 2007 - Insidermedicine) Early exposure to vaccines containing mercury does not cause mental deficits in children, according to research published in the New England Journal of Medicine.

Thimerosal is a type of mercury that has been used as a preservative in vaccines since the 1930s. While no harmful effects have been reported from mercury at doses used in vaccines, vaccine manufacturers have begun eliminating mercury from vaccines as a precautionary measure. Today, with the exception of some flu vaccines, immunizations used in  preschool  children contain either trace amounts or no thimerosal .

Here is some additional information about vaccines:
•    Currently, vaccines are recommended against 12 vaccine-preventable disease
. All children with no established contraindications should receive vaccines against preventable diseases as outlined in the Unified Schedule of Childhood Immunizations.
•    Thimerosal is under ongoing investigation for its potential role in causing autism in children. To date there is no scientific evidence to support any association

In the present study, researchers studied more than 1,000 children aged seven to 10 who were exposed to mercury in vaccines. They administered standardized tests to assess 42 measures of mental functioning.

The researchers found only small associations between the vaccines and effects on the brain, and the effects were almost equally divided between positive and negative effects. For example, higher mercury exposure was associated with better performance on one measure of language and poorer performance on one measure of attention, organization and remembering details. One of the main shortcomings of the study is that it did not examine the possible association between autism and mercury exposure.

The controversy over the safety of mercury in vaccines will likely continue. In the meantime, parents need to know that vaccines protect against a host of dangerous and even deadly diseases, and the risks associated with not being vaccinated are considerable. Talk to your child’s doctor, and get the information you need to make an educated decision.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.