Title: Continuing Increases in Autism Reported
to California’s Developmental Services System
Authors: Robert Schechter, MD, MSc; Judith K. Grether, PhD
Source: Arch Gen Psychiatry. 2008;65(1):19-24
While we wait for the release of the new Academy of Pediatrics study on Thimerosal (see last blog entry), I thought this recent article from the Archives of General Psychiatry was worth reviewing, especially given the current controversy regarding ABC “Eli Stone” episode. This study was simple and elegant. It follows a straightforward logic. If the use of Thimerosal in vaccines has a causal role in the development of autism, the elimination of Thimerosal in vaccines should result in a drop in the rates of autism, or at the very least, a pause in the accelerated increase of these rates. To test this hypothesis the authors reviewed the rates of autism in the State of California from 1995 to 2007. The found a consistent increase in rates during these 11 years without any indication of a slowdown or a drop in autism rates. One particular finding is worth mentioning. The rates of autism in 3 to 5 year old kids increased from 3 to 4.1 per 1000 live births from 2004 to 2007, which represented a higher increase than those observed for all other developmental disabilities. This is of major importance because during this same period all but trace amounts of Thimerosal had been eliminated from vaccines in the State of California. If the link between Thimerosal and autism were “causal” and strong, the rates of autism during the 2004-2007 year should have dropped. Instead these rates increased. Now, although strong, this is far from conclusive evidence, since people could argue that rates continued to increase because of vaccinated babies moving to California or that such trace amounts of Thimerosal were enough to continue the increase in autism. But this last hypothesis will likely be answered by the Pediatrics article due to come out next week.
UPDATE: I found an interesting post at Autism in New Brunswick about a University of Kentucky professor’s (Dr. Boyd Haley) skepticism of this research based on the idea that mercury exposure continued after thimerosal was supposedly removed from vaccines in California (see the press story here). The difficulty with Dr. Haley’s argument is that I can’t find any reliable data showing that the levels of mercury in vaccines continued to be higher than trace amounts after Thimerosal was taken out of vaccines. At least I can’t find any published studies in scientific journals of such effect. It is difficult to believe that after Thimerosal was removed there was not a reduction in mercury exposure. Arguing that mercury exposure remained stable implies that either Thimerosal was not actually removed, that the new non-Thimerosal vaccines were so delayed to reach Drs offices as to not affect the overall mercury exposure, or that somehow these children continued to be exposed to mercury through a difference source. Otherwise, the most rational conclusion is to assume that mercury exposure was significantly reduced after Thimerosal was pulled from the market and therefore a parallel reduction in new cases with autism is expected. Sadly this didn’t happen.
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