Four Seasons Pediatrics

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Thimerosol – what is it?

As you see the news, stories abound, regarding thimerosol. These stories scare parents about doctors poisoning their children with thimerosal and causing autism. This frightening statement gets your attention and gains media attention. Why scare people now?

Thimerosal is an organic mercury based preservative used in vaccines and other products since the 1930’s. Starting in 1999, the manufacturers of vaccines have been voluntarily producing vaccines which are either “thimerosal free” or contain only “trace thimerosal”. This was done in an effort to lessen the amount of mercury a child will be exposed to early in life. Most of our mercury comes from the food we eat, especially fish, seafood and grains.

Mercury in high doses has been linked with problems with kidney function, immune function and learning difficulties. The Center for Disease Control (CDC) investigated the incidence of autism in relation to the amount of thimerosal received and found that those children receiving thimerosal were NOT more likely to be autistic or have other problems with their kidneys, immune function or learning difficulties. In 2004, the Institute of Medicine concluded that there is NO LINK between thimerosal containing vaccines and autism.  Multiple studies on hundreds of thousands of children have since been published showing no link as well.  Studies will continue and the news will continue to report heartwrenching stories. Our recommendation will always be based on the most current scientific data available, not speculation.

The vaccines we use are thimerosal free with the exception of some of the influenza vaccine for children over 3.  When preservative free flu shots over 3 are not available, we will order those with thimerosal as a preservative.   The amount in 1 flu shot is less than Flumist (nasal flu vaccine) is thimerosal free.

How much is too much for thimerosol?

  • Thimerosal free: no detectable levels of thimerosal
  • Trace thimerosal: under 0.5 micrograms of thimerosal
  • Thimerosal vaccines: 12.5-25 micrograms of thimerosal (this is not the same as methylmercury and does not stay like methyl mercury)
  • One can of tuna fish: about 87 micrograms of methyl mercury (stays in the body)
  • World Health Organization allowable 1st year of life exposure: 200-230 micrograms of mercury
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