In what is considered a controversial article published in June 2005, Robert F. Kennedy, Jr. used research which suggested that it is not the vaccines themselves which contribute to autism, but a mercury-based preservative called thiomersal, which is used for some vaccine preparations (although not MMR), that may actually be a cause of autism. Kennedy went on to point out that autism was first noticed in children who were born around the time of the first use of thiomersal into commonly mass-produced vaccines, and further states that the incidence of autism in the US is well correlated with the amounts of thiomersal children receive in the first two years of life. Kennedy then went on to also note that the there is a very low reported cases of autism in the Amish, who do not immunize their children. The CDC has gone on the record stating that a link between thiomersal and autism was 'unlikely'.
In 1999 it was recommended by the Public Health Service (including the CDC, FDA, and NIH) that thiomersal should no longer be used when preparing vaccines for public use. While thiomersal was only used in a very few childhood vaccines by the year 2005, it still has not been shown that autism rates have dropped significantly as a result of the removal of thiomersal. The CDC as well as some medical organizations continue to claim that none of the available evidence is shown to support even a causal link between thiomersal and autism. Critics of the CDC have answered by claiming that the CDC analysis further demonstrates a deliberate bias in the CDC research.
For example, an analysis by Madsen et al. in Demark noted that the incidence of autism remained fairly constant while thiomersal was being phased out and started to rise beginning in 1991, even after thimerosal was discontinued in 1992. Critics of this analysis point out that the methodology was biased. Dissenters to the Denmark data point out a significant increase in autism rates among children whose childhood vaccines contained thiomersal. However, in Madsen et al.'s study, the amount in the vaccinations actually decreased while autism rates increased (specifically, during the period 1961–1970, infants had received a total of 400 µg of thiomersal by the age of 15 months, and during the period 1970–1992, infants had received a total of 250 µg at 10 months of age).
The California Department of Developmental Services (DDS), considered to have the best reporting system for autism in the US, has reported unprecedented decreases in the caseload increase. The caseload increase went from 734 during the second quarter of 2005 to 678 during the third quarter of 2005, a 7.5% decline in one quarter. Note that the total caseload handled by the state is still increasing, but the recent trend points to a deceleration in the trend. For example, from the 2nd to the 3rd quarter of 2004, the caseload went from 25,020 to 25,769 (a increase of 749 clients). Between the 1st and 2nd quarter of 2004, the caseload increased from 24,297 to 25,020 (a increase of 723 clients).
These variations have led to speculation that removal of thiomersal from vaccines in California is starting to pay off. Others point out they are unremarkable and may simply be an indication that the awareness curve is starting to level off, and that the rate of caseload increase should be expected to decrease to population growth levels (1.6% annual) eventually. Caseload increase between 2004 and 2005 was about 10%.
A study published in the March 2006 issue of the Journal of American Physicians and Surgeons (JPANDS) by Dr. Mark Geier claimed to show that "new cases" of autism in California dropped by as much as 35% following the removal of thimerosal from childhood vaccines. The study did not document incidence drops, however, and must also be noted that its definition of "new cases" is known to be flawed.
A study published in May 2006 by Dr. Mark Geier et al. indicates that the trends of newly diagnosed neurodevelopmental disorders (NDs) such as autism reported to VAERS "correspond directly to the expansion and subsequent contraction of the cumulative mercury dose to which children were exposed from TCVs through the U.S. immunization schedule."
A study which was due to be published in July of 2006 goes on to claim that the MMR vaccinations are definitely not the cause of autism or Asperger Syndrome.
For more information about autism and the autistic community be sure to check out the resources available at answers-about-autism.
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