In reviewing a new study published in the Archives of General Psychiatry, “Continuing Increases in Autism Reported to California's Developmental Services System” (January 7, 2007),1 The Deirdre Imus Environmental Center for Pediatric Oncology finds the study’s conclusions premature and inconsistent with published clinical research.
Using epidemiological data from the California Department of Developmental Disabilities (DDS), researchers Schechter and Grether reviewed the trends in autism in conjunction with decreasing amounts of thimerosal ethyl mercury exposure. The authors concluded, "The DDS data do not support the hypothesis that exposure to thimerosal during childhood is a primary cause of autism."
We do not believe this conclusion is supported by the methodology and results presented in the article. The study’s authors incorrectly cite how long mercury-containing vaccines remained in circulation in California and failed to account for the impact of the reintroduction of the mercury-containing influenza vaccine. The study also failed to provide evidence that thimerosal did not cause autism in a significant subset of children.
The American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) began recommending the influenza vaccine for infants and pregnant women in May 2002. This recommendation reintroduced significant amounts of mercury exposure in utero and again at 6 and 7 months of age.
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5102a1.htm
It should be noted that existing stocks of mercury-containing vaccines were not recalled; they remained on clinic shelves.
We also have no way of knowing precisely how much mercury remains in children’s vaccines today. Neither the FDA nor the CDC performs any oversight testing to validate the level of mercury currently remaining in children’s vaccines. Vaccine manufacturers report the amount of mercury in vaccines but we have no independent confirmation of those amounts. We are essentially expected to trust the manufacturers regarding mercury content in these vaccines. While “trace” amounts of thimerosal are still incorporated in several routine childhood vaccines, numerous studies have found very small amounts of mercury to be a potent developmental neurotoxin capable of causing the characteristics we see in children with autism. (Parran et al. Toxicol Sci 2005; 86: 132-140). Decades of published research have shown mercury to be particularly toxic to the developing fetus, infants and young children. Thimerosal is mercury and, as the AAP has noted, “Mercury in all its forms is toxic.”
The 2004 California law that would ban the use of mercury-containing vaccines for pregnant women and children under the age of three did not go into effect until December of 2006. The California’s DDS does not include children under the age of three years of age in their data. Because of the recommendation to give the mercury-containing influenza vaccine to pregnant women and young children, in combination with other “trace” amounts in other vaccines, it is clear that pregnant women and infants continued to receive mercury-containing vaccines. Therefore it is far too soon to leap to the conclusions made by the study’s authors.
The study fails to rule out that a subset of the population could have regressed into autism after inoculations with mercury-containing vaccines. If we are unable to exclude this possibility, and the subset is only 5% of the children diagnosed with autism, this could still represent thousands of children.
The authors’ reliance on strictly epidemiological data, while acknowledging the “absence of exposure data”, along with the failure to consider the toxicological significance of thimerosal documented in other studies, calls into question the study’s findings and the misleading conclusions reported in the media. The tripling of immunizations during the 1990’s, many of which contained mercury amounts that exceeded EPA safety guidelines cannot yet be dismissed as contributing to the increased prevalence of autism spectrum disorders in the United States.
Thimerosal may not be the only or the primary cause of autism. We cannot conclude that it has been eliminated as a possible contributor in a significant number of children. We wonder why are researchers still defending its use -- why aren't we simply removing all of it, even trace amounts, when this is clearly technically feasible? Would it make sense to inject trace amounts of lead into our babies?
The only valid conclusion based on the data presented is that autism is sadly still on the rise in California, as we’ve seen across the world. Given the continued use of thimerosal in routine childhood vaccines along with other ongoing environmental exposures to heavy metals, it is not possible to eliminate mercury as a contributing factor to this epidemic rise in autism. As we still do not know what causes the vast majority of autism cases, we should be studying all possible environmental triggers while cautiously avoiding any potential neurotoxin exposures.
We are in the midst of a public health crisis in need of urgent and immediate attention.
In the absence of a plausible explanation for a disorder that has gone from 1 in 10,000 to 1 in 150 in less than 20 years, we call on the CDC to declare autism a national emergency and for Congress to initiate oversight hearings to investigate what has happened to a generation of America’s children. This is an epidemic and we believe environmental factors are clearly implicated. There is no such thing as a genetic epidemic.
The Deirdre Imus Environmental Center for Pediatric Oncology® continues to support the need for an independent study that will investigate autism rates in vaccinated versus non-vaccinated populations and a significant investment of financial resources directed specifically towards environmental exposures and their affects on children’s health.
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1Schechter R., Grether JK. Continuing Increases in Autism Reported to California's Developmental Services System. Arch Gen Psychiatry. 2008. Vol 65(1); 19-24.
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Posted 1-10-08