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"Continuing Increases in Autism Reported to California's Developmental Services System"
Archives of General Psychiatry, Robert Schechter, MD (January 2008)


The entire study is based on the false premise that children's vaccines no longer contain mercury. But, may be helpful in raising the larger point that mercury is not the sole problem with vaccines, and it looked at a lot of kids in a reliable state for data, California. Conflict is high: lead author is in charge of California's immunization program.

Actual Question This Study Asked & Answered:

Q: Has the rate of autism in California decreased since thimerosal was "removed" from vaccines?

A: No.

Did the study look at unvaccinated children?


Conflict of Interest (from the study itself):

"This study was supported through the California Department of Public Health."

The lead author works in the immunization branch of the California Department of Health, his job is to give vaccines to children.

Ability to Generalize:

The study is so fatally flawed, there is nothing to generalize about. The study assumes that thimerosal was no longer in California’s vaccines for kids after 2002 which is simply a false assumption (see criticisms below for more detail). However, the study does make the point that autism continues to grow, which calls into question the entire vaccine schedule, rather than just one ingredient.

Post-Publication Criticism:

High, because the assumption of the study was flawed. Moreover, the study never looked at exposure data by child, it simply generalized and estimated.

Scoring (Out of 40 possible points):

Asked the Right Question: 1

Ability to Generalize: 0

Conflict of Interest: 0

Post-Publication Criticism: 0

Total Score: 1

Choice Excerpt from the Study:

"In the absence of exposure data for individuals or the population, we adjusted published estimates of maximum thimerosal exposure for infants and toddlers6 to reflect subsequent recommendations for influenza vaccine and the fact that the third doses of DTP, DTaP, Hib, and hepatitis B virus vaccines usually have not been recommended before 6 months of age. Based on these estimates, children aged 3 to 5 years (Figure 3) reported to the DDS since the first quarter of 2004 are assumed to have reduced exposure compared with children aged 3 to 5 years reported from 1995 through 2003."

Meaning: We don’t have actual thimerosal exposure data by child, and we also did not consider if any of the mom’s received mercury-based vaccines while pregnant, a practice that was recommended starting in 2002 (for the flu shot).

Guest Critic #1: Boyd Haley, Ph.D. Professor of Chemistry, University of Kentucky


8 January 2008

by Boyd Haley, Professor of Chemistry, University of Kentucky, Lexington, KY

We should all consider that there are two top priorities in the vaccine/autism issue every American should be concerned with. We need to develop a safe vaccination program, and we need to find the cause of autism and eliminate it if possible. I have been a strong proponent of investigating thimerosal as the casual agent for autism spectrum disorders based on the biological science that shows thimerosal to be incredibly toxic, especially to infants. I know of nothing remotely as toxic as thimerosal that numerous infants would be exposed to before 3 to 4 years of age. Below I present several comments regarding this issue and the 2008 Schechter-Grether study that I think are relevant. Mainly, while the Schechter-Grether study appears to be a well done study it suffers from the fatal flaw of assuming that thimerosal was removed to safe levels in vaccines by 2002. They also cut a fine edge as to time when a significant drop in autism rates would be expected. Further, no study exists that proves our vaccine schedule alone is safe, let alone the current one that still exposes infants to thimerosal, a concern they do not address. The alarming concern is that these authors seem more involved at providing material saying thimerosal is safe than they are concerned with the obvious fact, openly presented in their own data on autism rates, which strongly indicated that increased rates of autism started with the CDC mandated vaccine program. References to support the comments are readily available in many recent publications.

  1. Autism was not a known, described illness until about 1941-3, 8 to 10 years after the introduction of thimerosal and similar organic thiol-mercury compounds in biological mixtures used in medicine and other areas. This argues against autism being a genetic illness.
  2. In 1977, 10 of 13 infants treated in a single hospital by topical application of thimerosal for umbilical cord infections died of mercury toxicity. This same topical was used on adolescents without obvious ill effects which strongly supports the concept that infants are very susceptible to thimerosal toxicity.
  3. The recent increase (starting about 1990) of autism spectrum disorders correlated well with the advent of the CDC mandated vaccine program which increased thimerosal exposures with increased vaccinations. Due to its toxicity, thimerosal would have to be suspect for causing autism.
  4. As expected by science, extensive searching for a genetic cause of autism has not turned up a significant find that would explain the recent increased rate in autism. The latest genetic find, at best, might explain 0.5% of autism causation. Most agree that a genetic predisposition is likely (like those that lead to low glutathione levels), but that a toxic exposure is absolutely needed. Consider also, that this increased toxic exposure would have had to occur in all 50 states at about the same time as all states have reported similar increases in autism rates. Only something like the government recommended vaccine program fits this need for a time dependent, uniform exposure of a toxin throughout all the states.
  5. In the Schechter-Grether study it is implied or assumed that all thimerosal containing vaccines were gone by the end of 2002 due to their expiration dates. I don't think this is a valid assumption. I have talked to mothers who asked to see the vaccine inserts as late as 2004 and found thimerosal present as a preservative in infant vaccines being used in certain clinics. Also, in 2004 the influenza vaccine was recommended by the CDC for infants 6 months of age and older. It would appear as if a thimerosal free vaccine time-frame would be very hard to identify, if one ever existed. I have read that the average age of autism diagnosis is near 44 months of age. Therefore, while it does seem reasonable to expect a decrease in autism after 4 to 5 years of complete thimerosal removal, assuming a consistent diagnostic protocol was used, it appears this has not been accomplished. This means the Schechter-Grether study is likely somewhat premature in reaching the conclusions reported in that enough time has not passed for the expected decrease to occur and that they were quite optimistic in identifying the dates of thimerosal reduction and underestimate exposures occurring between 2002-4.
  6. If, indeed, the complete removal of thimerosal from vaccines was not followed in an appropriate time by a decrease in autism then this would be solid proof that thimerosal was not causal for autism. However, thimerosal has not been completely removed from vaccines and thimerosal used at the original levels in the manufacturing of these vaccines with a trace amounts left in the vaccines when bottled. I don't know what level a 'trace' is since it is not a term used in science to describe an actual amount. Some called the 12.5 micrograms mercury in the older vaccines a a 'trace' amount. Bottom line, the infants are still getting some level of thimerosal, a 'trace'amount that is free and an amount of ethylmercury that is bound to the proteins that induce the immune response.

    If vaccines are causing autism and it appears this is a strong possibility based on the California data and, if removing thimerosal added as a preservative really does not reduce the autism rate then the causation is much more complex.

    Consider the possibilities that:

    A. Autism may be caused by a thimerosal modified protein that sets off an immune response or causes some other biological reaction that can cascade with injurious effects. Since the vaccines are manufactured with thimerosal present in abundance it is quite likely that any cysteine containing proteins would be modified with ethylmercury. Removal of most of the free thimerosal (or just not adding it) would not decrease the level of any toxic modified protein produced during the vaccines production that might be causal. Removing the thimerosal added as a preservative would not decrease the amount of this ethylmercury modified protein in those vaccines with a 'trace' thimerosal levels.

    B. That autism could be caused in susceptible individuals by very low thimerosal or ethylmercury modified protein exposures due to their genetic susceptibility or other factors (general health, gender). In this scenario the higher thimerosal exposures are not required and the induction of autism is not thimerosal concentration dependent at the old and new thimerosal vaccine levels, but just requires a significant exposure level that is met by the vaccines containing the lower a 'trace' amounts of thimerosal and past thimerosal levels in vaccine production processes.

    Bottom line, if genetic susceptibility is involved then causation of autism may not increase linearly with increased thimerosal exposure. Causation may only require low thimerosal exposure or exposure to modified proteins. It is possible that the reduction of thimerosal as in the a 'trace' was just not enough to produce a safe vaccine.

    Not all toxins work like alcohol and the old 'a dose makes the toxin' is not always correct. As long as they are used, the mere use of 'a trace' thimerosal in vaccines along with higher levels in the flu vaccine will always prevent a conclusive answer to thimerosal's involvement in autism causation. What should be studied is the "no exposure" versus the "exposed" populations with regard to autism rates.

  7. If indeed autism is rare among the non-vaccinated Amish populations, as reported by Dan Olmstead, I find it an amazingly oversight that the CDC and others responsible for infant health do not fund a study in this area.

    This study could go both ways, if the Amish have autism rates identical with the rest of the population the argument would be over -- neither vaccines nor thimerosal would be causal for autism, and I personally would argue in this direction. If, however, the autism rates in the Amish are exceptionally low then vaccines would have to be considered as a prime suspect in causation with the presence of the highly toxic thimerosal the main suspect.

    If the results in the 2008 Schechter-Grether study hold up with time, and complete removal of thimerosal does not cause a drop in autism rates and the autism rates in non-vaccinated populations are low then something else in the vaccines would have to be considered the major causation factor for autism. However, without doing the non-vaccinated population studies there cannot be a conclusive statement either way about either vaccines or thimerosal as being causal for autism. The steadfast refusal of the CDC and others to support such studies being done is part of the reason that many parents, scientists and physicians have severe doubts about the sincerity of their efforts to resolve this issue. This is how I think, when I review a paper submitted for publication I always ask why an obvious experiment wasn't done. The study of non-vaccinated populations is a very obvious experiment that the CDC and its supporters appear to refuse to consider. This makes me suspicious that this knowledge exists and is being suppressed because knowledge of the rate among the non-vaccinated population would answer many questions.

    Finally, the Schechter-Grether study may be good news to the vaccine manufacturers and those who recommended and use the mandated vaccine program as it serves as manufactured uncertainty about the thimerosal involvement in autism causation. However, it presents a major concern to the parents and families of infants since it implies that our vaccines, even with most of the free thimerosal removed, may not be safe and that our CDC does not have a clue about what to do make them safe. Common sense would lead most to attack finding the cause of autism instead of trying to prove something besides thimerosal is causal. The major question is "are our vaccines causing autism?" -- only comparing the non-vaccinated to the vaccinated will answer this question. Common sense would have lead to this comparison being done first and being done 10-15 years ago. In the recent past I have recommended that parents vaccinate their children with thimerosal free vaccines as I considered them safe. If Schechter-Grether are correct, and vaccines, but not thimerosal, correlate with increased autism rates, then I am in error assuming vaccines are now safer with regards to autism risk than they were 2000.

Guest Critic #2: Deirdre Imus Environmental Center for Pediatric Oncology

Statement on California Autism Study

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.

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 110 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.