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The Long Awaited CDC Trial on Thimerosal and Autism

by Steven Novella, Sep 13 2010

We can add one more study to the pile of evidence showing no association between exposure to thimerosal (a mercury-based vaccine preservative) and autism. The article: Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism, is published in the latest issue of Pediatrics, and shows no association between prenatal and infant exposure to thimerosal and three forms of autism – autism, autism spectrum disorder, and regressive autism.

No one study can ever be definitive, but now we have a large body of evidence from multiple studies showing a lack of association between thimerosal and autism. This won't stop the dedicated anti-vaccinationists and mercury militia from continuing their anti-vaccine propaganda, but hopefully it will further reassure those who actually care about the science.


This has been a long and complex story, so let me review some of the background. Diagnosis rates of ASD have been climbing for the last 20 years, prompting some to search for an environmental cause. The existing anti-vaccine community, not surprisingly, blamed vaccines. This was given a tremendous boost by the now-discredited study by Andrew Wakefield concerning MMR (which never contained thimerosal) and autism. When the evidence was going against MMR as a cause, attention turned to thimerosal in some vaccines. This notion was popularized by journalist David Kirby in his book, Evidence of Harm.

However, this important premise of a correlation – rising ASD rates – is not as simple as the anti-vaccine crowd assumes. In fact there have been many studies of autism prevalence and the consensus at this time is that most of the increase in ASD is due to a broadened diagnosis, diagnostic substitution, and increased surveillance. There may be a real small increase, but most if not all of the increase is an artifact of diagnosis, not a real increase. (Side note – I have written about this topic many times before, and the links I will provide for background are to my previous reviews and summaries, not the original research. But of course, the links to the original research can be found in my prior articles.)

As further support of this a recent NHS study found a consistent prevalence of autism of about 1% in all age groups. If autism rates were truly increasing we would expect a lower prevalence in older age groups, but that is not what they found.

Another line of evidence is the younger and younger identification of signs of autism. Formal diagnosis is often made around 2-3 years old, after many vaccines are given. But numerous recent studies have documented signs of autism as young as 6 months of age. This makes it difficult to blame vaccines given after 6 months.

Holdouts for vaccines as an important contributor to autism rates have pointed to prenatal vaccines given to the mother, but a study finds no correlation there either.

Where the “mercury militia” gains their only support is from the fact that mercury is indeed a known toxin, and a neurotoxin. However, there are still problems with the notion that mercury toxicity from thimerosal causes any neurological damage or specifically contributes to autism rates. The first is that thimerosal contains ethylmercury, which is not nearly as toxic as methylmercury, the form that is found in fish and other environmental sources. Second, the doses given is vaccines is well  below safety limits. Anti-vaccinationists argue that the cumulative dose is high enough to cause damage, but there is no evidence for this. What there is evidence for is the fact that infants excrete mercury very efficiently, and therefore likely clear their mercury load after one vaccine and before the next, so it does not accumulate. And finally – mercury toxicity does not resemble autism (despite the false claims of the anti-vaccine crowd).

Another line of evidence that presents problems for the vaccine hypothesis of autism is the massive and growing evidence that autism is dominantly a genetic (not environmental) disorder. Of course, genes interact with the environment, and there may be environmental factors, but the dominant factor is genetic.

In addition to the multiple independent lines of evidence all arguing against a link between vaccines in general and thimerosal in particular to ASD, there is the ecological and epidemiological evidence which looks specifically at if there is any correlation between thimerosal exposure and risk of autism. Here the answer is a clear – no. There have been multiple such studies in multiple countries (summarized here) showing no correlation.

In addition, A recent Italian study showed no link between the amount of thimerosal exposure and autism risk. Another study showed no correlation between blood levels of mercury and risk of autism.

But the most compelling evidence against a link came from the removal of thimerosal from the routine childhood vaccine schedule in the US. By the end of 2002 all thimerosal, except for insignificant trace amounts, was removed from all vaccines given routinely to children. Only some flu vaccines still contained a small amount of thimerosal, but this is an optional vaccine with thimerosal-free options. The result was a dramatic plummet of thimerosal exposure in the US childhood population. If thimerosal were a significant contributor to autism incidence then we should have also seen a plummet in autism rates. David Kirby predicted this, and the anti-vaccine movement agreed. They gloated about the day they would be proven undeniably correct.

But now it has been 8 years – and autism rates continue to rise at the same rate, without so much as a blip. They tried to move the goalposts for a while, and make some desperate arguments to rescue their failed predictions, but there is no hope. There is no rational conclusion remaining except that thimerosal in vaccines is not a measurable contributor to autism rates.

The CDC Studies

Three years ago I wrote about a CDC study that looked at thimerosal exposure and 42 different neurological outcomes (but not autism). What they found was that there were a few scores that were worse among those exposed to more thimerosal, but there were also a few scores that were better. There was a random distribution of slight positive and negative effects that essentially average out to no net effect. It’s all just noise.

The bottom line is that this study showed no correlation between thimerosal exposure and adverse neurological outcomes.

At the time we were promised a follow up study of similar design that looked specifically at autism – and now, after a three year wait, we finally have those results. This is a case-control observational study that looked at managed care organization (MCO) members for their history of vaccination, including pre-natal vaccination, as well as exposure to thimerosal through immunoglobulins. They correlated thimerosal exposure from these sources to later diagnosis with autism, autism spectrum disorder, and regressive autism. They found:

RESULTS: There were no findings of increased risk for any of the 3 ASD outcomes. The adjusted odds ratios (95% confidence intervals) for ASD associated with a 2-SD increase in ethylmercury exposure were 1.12 (0.83–1.51) for prenatal exposure, 0.88 (0.62–1.26) for exposure from birth to 1 month, 0.60 (0.36–0.99) for exposure from birth to 7 months, and 0.60 (0.32– 0.97) for exposure from birth to 20 months.
CONCLUSIONS: In our study of MCO members, prenatal and early-life exposure to ethylmercury from thimerosal-containing vaccines and immunoglobulin preparations was not related to increased risk of ASDs.

The strengths of this study are the large numbers, the thorough assessment of ethylmercury exposure, and the confirmation of diagnosis. However, this is not a perfect study – it suffers from the limitations of observations studies, as the authors point out in their discussion. The primary weakness was the fact that of 771 potential case-children and 2760 controls they ended up with 246 cases-children and 752 controls. Around 12% were not eligible for various reasons, and the rest were not able to participate for various reasons (because they could not be located, for example), but most of the drop out was simply because potential subjects did not wish to participate.

This high percentage not participating in the study opens the door wide for bias in the final results. The authors were fairly thorough in exploring possible sources of bias from this fact. They found that study participants did not differ significantly from those not participating in various key aspects – such as having an older sibling with autism. Also most case-children were diagnosed with autism after their infant vaccines, so this unlikely to have affected vaccination rate.

But of course it is always possible for there to be unknown confounding factors biasing the results.  A protective effect from thimerosal is biologically implausible, so these results are due to either random chance or some bias in reporting or participation that is not apparent.

Even still, if there were a significant causal effect from thimerosal it should be apparent in this type of study, and it wasn't.


No one study, especially an observational study, is ever very compelling. I don't think this one new study changes the scientific picture of vaccines or thimerosal and autism. But it is one more study that fails to show any correlation between thimerosal exposure and risk of developing autism or ASD. This comes on top of multiple independent lines of evidence all pointing away from the notion that vaccines or thimerosal are a significant cause of autism.

The scientific community is likely to see this as further confirmation of a lack of association between vaccines and autism – just one more piece of the big picture. The anti-vaccine community is likely to dismiss it as either hopelessly flawed or as part of the conspiracy. In other words – this study is unlikely to change anyone's mind on this issue.

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43 Responses to “The Long Awaited CDC Trial on Thimerosal and Autism”

  1. steelsheen11b says:

    Another study to add to the pile of studies that say the same thing isn’t going to deter the anti-vaccine nutters. Those dogmatic and down right stupid freaks will hold onto to their discredited Lancet study until it is pried from the cold dead hands of their children. Was that too dickish?

    • RoberttheFoul says:

      Not at all dickish, steelsheen11b. Sadly, though, it is all too true. It is my fervent wish that we could round up these types of knuckleheaded fools and forcibly sterilize them. They shouldn’t be allowed to breed.

  2. Alex says:

    These types of studies do push the anti-vacc’ers further into the fringe in the eyes of the mainstream. There will always be a tinfoil hat brigade.

  3. Chris Howard says:

    Considering that lives are on the line, it may not be dickish, enough. At least you’re an “Ethical Dick” ;-)

  4. MadScientist says:

    “No one study can ever be definitive” – I find that misleading. If a study has a large enough population and is designed well, then the certainty in the results makes any claim that mercury causes autism outright ridiculous. This is because the negative results will imply that even if mercury *did* cause autism, the rate must be smaller than some number which can be estimated from the study. Has anyone done their calculations and determined what rate mercury would contribute to autism if we assumed apriori that it does? The results of investigations which are conducted well can even be agglomerated in many circumstances and that would tend, overall, to to reduce the maximum estimated affliction rate for autism. Perhaps the message should be something like “we don’t believe that mercury causes autism, but if we were to assume it does then it does so in less than 0.0001% of autism cases.”

    • Jason says:

      That would be difficult to calculate as “increased cumulative exposure in the age ranges from birth to 7 months and birth to 20 months were both associated with decreased risk of all 3 ASD outcomes.” In other words, the effect, if it exists, is so small that it is overwhelmed by other variables associated with children who get vaccines (i.e., parental age, education, etc). Either that or the vaccine actually prevents Autism! (sarcasm).

      • MadScientist says:

        But even if other things dominate, that still puts an upper limit on any possible effects of mercury; if anything it would result in a very generous upper limit. Don’t give antivaxxers the idea that mercury prevents autism; next thing you know there will be nuts out there giving kids large doses of mercury compounds (and the poor kids will probably be taken to “chelation therapy” afterwards.)

  5. Max says:

    “The anti-vaccine community is likely to dismiss it as either hopelessly flawed or as part of the conspiracy.”

    Exactly, they automatically dismiss CDC studies. If you want to convince them, explain why they should trust the CDC and FDA over Wakefield et al. Explain that the government studies are peer-reviewed, provide examples of FDA recalls of FDA approved drugs, attack Wakefield’s credibility.
    And explain the anecdotal evidence of healthy babies getting vaccinated and never being the same again. If it’s coincidence, what are the odds?

  6. gwen says:

    The AOA has announced that they are publishing a book this month that will definitively PROVE that mercury has caused an epidemic of autism.
    I wonder what their ‘proofs’ are? Probably not much different than their previous claims.

    • Chris says:

      If it is this book, you can be guaranteed it will be complete crap (the tag I added).

      The authors include a co-writer of the paper Autism, a Novel Form of Mercury Poisoning and a former journalist who wrote that the Amish don’t vaccinate (they do), and don’t have autism (but completely missed the Clinic for Special Children that studies the Amish, their genetics and their disorders). Their writings at AoA are often shredded to bits at Orac’s Respectful Insolence blog (both are characters in a little play written by Orac today).

  7. Dear Dr. Novella,

    RE: Your article “The Long Awaited CDC Trial on Thimerosal and Autism”

    The most recent paper: “Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism” published online by Pediatrics is a prime example of pseudoscience at its worst.

    If the goal were to see an effect for Thimerosal, then the valid comparison would have been between a group whose mothers received Thimerosal-preserved RhoGAM and the children were given all Thimerosal-preserved vaccines and a MATCHED “control” group whose mothers received WinRho (a no mercury equivalent to RhoGAM) and children who received equal amounts “no Thimerosal” vaccines.

    All that the current study does do is again establish the reality that NOT all children who receive Thimerosal-preserved vaccines get autism — that there is some “susceptibility” factor or, more probably, factors at work.

    For a recent scientific paper that forthrightly compared autistic children and much better matched controls (who all received near equal amounts of the same vaccines — many doses of which are Thimerosal-preserved), this researcher would recommend that all download and carefully study the “Polish” paper:
    Majewska MD, Urbanowicz E, Rok-Bujko P, Namysłowska I, Mierzejewski P. Age-dependent lower or higher levels of hair mercury in autistic children than in healthy controls. Acta Neurobiol Exp 2010, 70(2): 196–208. []

    For additional papers and articles that support a strong link between Thimerosal-preserved vaccines and autism (as well as other epidemic chronic diseases in children), please read this researcher’s
    review: “Review of recent publications that show Thimerosal-preserved vaccines are major cause of current chronic-condition ‘autism’ epidemic” by Paul G. King, PhD, CoMeD Science Advisor, Science Advisor to the National Coalition of Organized Women (NCOW), and a Science Advisor to StS and other groups, which can be found in the 2010 Documents on or at:

    Looking forward to receiving a cogent response to the issues raised.


    Dr. King

    • Chris says:

      Dr. King, exactly how many women out of the entire population get RhoGAM during their pregnancy? Really?

      How does it compare to women who eat fish and get more of the more dangerous methylmercury?

      Isn’t this just moving the goalposts because the whole “thimerosal in vaccines” is just so 1990s? They were removed, and no effect on autism rates (though total numbers of children served in special education has not changed).

      The Polish study you referenced is discussed here and here.

    • MadScientist says:

      Obviously you never worked as a medical researcher and don’t now the first thing about experimentation and what constitutes a reasonable control. Instead you push bullshit articles which really do not have proper controls or valid conclusions from their worthless data. By the way, there really *are* UFOs – just read any of the self-published and peer-published UFO literature. So-called doctors like you make me (and your patients) sick.

      • Dear Chris,

        1. For the time period in question, 10 to 15+ % of all pregnancies in the USA (depending upon the race of the mother) received one or more doses of Thimerosal-preserved a Rho(D) product with more than 90% getting the RhoGAM product.
        2. In general: a) pregnant women in the USA are NOT heavy fish eaters, b) US women have been warned to limit fish comsumption during pregnancy since the mid-1990s, c) in general, more than 75% of the ingested mercury in fish is not aabsorbed but simple excreted in the feces, and d) in comparative human brain- and fetal- cell studies and in animal studies at low-exposure levels during development methylmercury hydroxide has been repeatedly been shown to be much less mercury toxic (as measured by long-term mercury levels in the brain) to the brain than Thimerosal.

        3. In Denmark where Thimerosal truly was removed from all childhood vaccines and no mass annual flu-shot vaccination of pregnant women and children with Thimerosal-preserved flu shots is recommended by the government, the CURRENT “pervassive developmental disorders”/”autism spectrum disorders” incidence level is below 1 in 1500. In the USA where giving Thimerosal-preserved flu shots to pregnant women and children has been in the official recommendations published in the MMWR since 2002 and with the extension of the recommendations to vaccinate children annually for flu until 18 years of age and with the “Pandemic” flu program’s extra doses (most all of which were Thimerosal-preserved and this year’s flu shots where most all DOSES that can be given to children and pregnant women are Thimerosal-preserved doses, the exposure level for children whose mother receive such and then also get such Thimerosal-preserved vaccines now exceeds the early childhood exposures from Thimerosal-preserved childhood vaccines AND the autism rate in the USA is > 1 in 110 (and, based on the DOD’s data for military children, probabley greater than 1 in 86). All that you are speaking of about the USA is a shell game — where the mercury was removed from some vaccines and a replacement vaccine (the Thimerosal-preserved flu shot) was substituted to continue providing the mercury. So the goalposts have not been moved — only the source of the injected vaccine mercury has been moved. Since the comparable rates for “autism” in Denmark ( 1 in 100) and probably are more than 15 times lower, nothing has changed, the US government has continued to recommend mercury poisoning our pregnant women and babies with Thimerosal-preserved vaccines and Denmark has stopped (in the early 1990s) mercury-poisoning their pregnant women and babies (and has stopped reporting any official incidence rates for their children).

        Dear MadScientist,

        Please read this response to Chris. I see no need to respond to your unsubstantiated personal attacks.

      • Max says:

        “in general, more than 75% of the ingested mercury in fish is not aabsorbed but simple excreted in the feces”

        Are you sure you’re not confusing methylmercury with elemental mercury?
        “Approximately 95% of ingested methylmercury is absorbed”

      • Chris says:

        Wait! You expect me to believe an argument by assertion? Where is the documentation that shows “10 to 15+ % of all pregnancies in the USA (depending upon the race of the mother) received one or more doses of Thimerosal-preserved a Rho(D)”, and that pregnant women are not heavy fish eaters?

        I know that I was encouraged to eat salmon and other fish during my pregnancy through the What To Eat While You are Expecting book.

        Really, why am I supposed to believe you without documented evidence?

      • Chris says:

        While you are finding the actual papers to document your assertions, perhaps you can point out where autism is actually caused by thimerosal, especially by RhoGAM.

        By the way, lawsuit motivated papers by the Geiers will not be acceptable. And neither will be papers published in “Medical Hypothesis” nor “Medical Veritas.”

      • MadScientist says:

        You’ve got a lot of bullshit words strung together but nothing of substance.

      • Chris says:

        Also, is there actual evidence that most of the children diagnosed with autism had mothers given RhoGAM?

      • chantilly says:

        Dear MadScientist,
        Either you work for a farmacologue group or the government, either you are a complete stupid shallowminded person. Im so sorry for you, but if you try to see things from a neutral point of view, you’ll see that the big pharmacological industries only want to make money and for that they need to be credible, so even if the vaccins are very bad and dangerous for us they are making so much money and they are powerfull so they have a “hand” in the government, is the same for the pesticides and chemical agricultural produits, we are killing ourselfs.. or you also thing “natural gas” is a good thing?? Poor you!

    • Prometheus says:

      Dr. King,

      Could you please explain the reason why a study that looked at thimerosal dose in autistic vs non-autistic age-, sex, and HMO-matched controls would generate a different result than a study that looked at autism prevalence in “full thimerosal” vs “no thimerosal”?

      If you can’t see that these are complementary studies (i.e. the same study with the axes rotated 90 degrees), then please take a few days to research this question further.

      The study done by Price et al gives more information than the one proposed by Dr. King because it treats autism as a binary variable (“yes” or “no”) – which is in keeping with how the diagnosis is made – and keeps the thimerosal dose as a continuous variable. Dr. King’s proposed study would not only be difficult to recruit for (as it would reject any subjects who had received a single thimerosal-containing drug and any subject that had received a single non-thimerosal-containing vaccine or RhoGam dose), it would also discard the data contained in the thimerosal dose-response.

      So, rather than being content with a better quality study than he proposes, Dr. King insists that we need to waste more time, research resources and money doing a lower quality study?

      The question Dr. King needs to ask himself is whether any study – done by any researcher – would satisfy him if the results did not conform to his expectation that mercury causes autism? Based on his replies, I think the answer is “No!”.


  8. laursaurus says:

    I have to admit that there are few areas of pseudoscience that evoke an emotional response(anger) from me. The anti-vax movement is probably number one on that list. Willfully preventing their own children from receiving basic medical care is reprehensible to begin with. But they also pose a deadly risk to the rest of society.

    Back in the early 90′s, there was a measles outbreak on a Medical/Surgical floor in the hospital where I was working. Evidently, a family member brought along an exposed, un-vaccinated child during a visit. Several elderly and immuno-compromised patients became infected. Needless to say, this was a huge deal to the entire facility. Every employee had to be screened for measle-antibody titre. I was among the group that required a booster, so in a sense I indirectly benefited from the tragedy. The OB ward was located on the same floor which permitted sibling visitation. Hospital administration had no choice but to change the policy, knowing it would have an impact on maternity admissions.
    The Health Department in our county provides childhood immunizations for $5 per session. A bilingual sign posted in the waiting room states that regardless of ability to pay even this negligible sum, no child will be refused (IOW, free). Poor Big Pharma is undoubtedly suffering tremendous profit loss, I guess.

    Vaccination is a moral obligation to society unless medically contra-indicated.

  9. Mad – you are talking only about the power of the study, and within that context you are correct. But there is also confounding factors, and the need for replication. Any one study can have hidden flaws. That is why we rely upon the consensus of studies.

    • Dear laursaurus,

      You are entitled to your beliefs and mischaracterizations.

      After all, most of theparents who have vaccine-damaged children were pro-vaccine parents until they found that on average about 25+ % of their children have one or more lifetime chronic childhood diseases that were apparently caused by or triggered by one or more of the vaccinations their child received.

      An illogical “war story” about your experiences provides little in the way of scientific support for your statements. But, all religious persons are entitled to their personal beliefs no matter what god or gods they worship.

      As far as the vaccines that are “given away”, both pharma and part of the federal govenment get paid for every dose dispensed and the net margins on all but the oldest vaccines are certainly more than 100 % of all costs — with government protection from being held accountable if a particular vaccine lot harms hundreds of cildren or, with few exceptions, adults in most instances. So your “Poor Big Pharma” is proverbially laughing all the way to the bank while continuing to spout the propaganda that vaccines are not big money makers.

      Unless: a) vaccination is effective in providing near lifetime immunity to essentially all of those who are vaccinated and b) the society has agreed to AUTOMATICALLY pay, without any arguing, for any lost time, suffering or injury that the person vaccinated receives and to fully support his or her family during the period of any vaccine injury’s duration or, if the person dies, for his or her family’s lifetime, then NO individual should have any obligation, moral or otherwise, to be vaccinated with a vaccine that: a) is not guaranteed to protect him or her from contracting any strain of the disease, and/or b) is not guaranteed to protect him or her for a “lifetime” (at least 50 years) without any need for booster shots, and/or c) is not cost-effective on a societal basis.

      Dear Steven Novella,

      It is the scientific validity of a study and the ability of unbiased independent reserchers to evaluate the same data or exactly replicate the experiment and support the study’s findings that should be used to judge each study. These requirements are certainly the minimum for any study that is a statistical examination of records (an epidemiological study of any kind).

      After all, there was a time, not too long ago, when the consensus was that the world was flat.

      Or, more recently, that nothing could travel “faster than the speed of light”.

      Moreover, when it comes to scientifically valid studies that can be independently reviewed linking the level of Thimerosal exposure to the risk of an adverse neurodevelopmental outcome, the studies usually cited by those who support the status quo must be disqualified because, in most cases, the original datasets have been “lost” (e.g., the “Verstraeten” and “Fombonne” studies) or access to the original raw datasets has been denied to qualified independent researchers has been denied (e.g., the epidemiological studies using the English, Danish and Swedish populations).

  10. Paul Kings objections to the current study are not valid. This study clearly demonstrates a lack of association between thimerosal dose and the risk of autism. It is an observational study, so of course there are always better controlled experimental study designs – but to dismiss the results on that basis is not valid.

    But that is how King proceeds – he picks apart anything he doesn’t like by focusing on picky and non-relevant details or turning molehills into mountains.

    That you would cherry pick the Majewska study is odd. The results show: “Autistic children significantly differed from healthy peers in the concentrations of mercury in hair: younger autistics had lower levels, while older – higher levels than their respective controls. The results suggest that autistic children differ from healthy children in metabolism of mercury, which seems to change with age.”

    This, if anyone, goes against the mercury hypothesis, as it suggests younger autistic children clear mercury faster or have lower exposure. If mercury causes autism then the higher level should occur when younger – before the onset of autism.

    However – I think this is just a small study with random results, and probably not real. Other studies show no correlation.

    Interesting – you dismiss the current study as pseudoscience, then promote a small study with questionable results that do not even support your hypothesis.

    • MadScientist says:

      The Majewska study is also a prime example of how not to write a paper or conduct an experiment. On the one hand “no consistent difference across groups” is mentioned at least twice, and that’s a conclusion which is supported by the data they present, but they also go fishing and make outrageous claims, present information in bizarre ways which I can only guess is intended to help support whatever argument they want to support – for example, why do they combine results from the male and female groups at some points and present them separately in others? It’s trivial to make a table which presents all information for all the categories. I was laughing at the claim of “matching” the birth order – and we see “birth orders” of 1.4, 1.5, 1.6 – so unless you have a weird method of counting birth order, the birth order is actually random. Since it’s rare for modern families to be very large, the birth order means nothing in that paper. Even the analysis of the hair mercury results is meaningless; the authors obviously don’t know any statistics, they only know how to push buttons in “Statistica”. For any claims about hair mercury to be of any relevance whatsoever, more information is needed – specifically the typical distribution of values in a population, which in turn informs you of the likelihood of seeing “significant” differences between sample groups given the size of the group. The fact that mercury in hair is higher for one age group than another (keep in mind that the age difference is only a few years) is an indication that the results are not significant as claimed – but as I said, the study does not have enough relevant information to support a strong conclusion one way or another (although it does favor the “no consistent difference” claim of Majewska).

    • Dear Dr. Novella,

      1. With respect to your:
      “Paul King[']s objections to the current study
      are not valid”,
      please provide me with some objective evidence to
      support your statement.

      2. With respect to your:
      “This study clearly demonstrates a lack of association
      between thimerosal dose and the risk of autism”,
      if you believe that the study is a scientifically sound
      study, please explain why, according to the Results for
      children who were exposed from birth to 7 months and
      birth to 20 months:
      “RESULTS: There were no findings of increased risk for
      any of the 3 ASD outcomes. The adjusted odds ratios
      (95% confidence intervals) for ASD associated with a
      2-SD increase in ethylmercury exposure were 1.12 (0.83–
      1.51) for prenatal exposure, 0.88 (0.62–1.26) for
      exposure from birth to 1 month, 0.60 (0.36–0.99) for
      exposure from birth to 7 months, and 0.60 (0.32–0.97)
      for exposure from birth to 20 months”
      that the findings indicate that being vaccinated with
      Thimerosal-preserved vaccines REDUCES the risk for
      children having “autism”? Do you really expect me or any
      other competent scientist who knows the TOXICITY of
      Thimerosal to accept that a study with such IRRATIONAL and
      NONSENSICAL results is a scientifically sound study?

      3. Clearly, your statements indicate that you did not carefully
      read and/or, for other reasons, failed to understand the
      Majewska study — which was only cited because it was a
      TRUE case vs. matched control comparative study where all
      the children received near equal doses of vaccines and only
      vaccine injury in the females with “autism” significantly
      reduced the number of vaccine doses in that group that
      attempted to assess what were the differences between the
      affected children and the carefully matched controls. It
      found that, the younger children excreted less of the
      mercury dose they had received compared to the children in
      the younger-children MATCHED control group. In the older
      children, who were beyond the age in which additional
      doses of Thimerosal-preserved vaccines were given, the
      affected children’s excretion levels were higher BECAUSE
      they were still trying to detox from the Thimerosal-
      preserved vaccines they had received than the excretion
      levels of mercury in the hair in the older-children
      matched controls who had already excreted much more of the
      toxic doses of mercury with which they had been injected
      years earlier. Hopefully, this general explaination will
      help you to understand that part of their findings and also
      to accept their:
      Autistic and healthy children differ in prevalence of
      abnormal development, frequency of adverse reactions to
      vaccinations and concentrations of mercury in hair,
      which change with development. The data indirectly
      imply vaccinations and mercurials as potential factors
      in autism pathogenesis.”

      Returning to the pseudoscientific study, the flaws are
      obvious to those who understand statistical population
      studies. The most serious are: a) the cases and controls
      are NOT truly MATCHED; b) the dosing is NOT truly MATCHED;
      c) the cases chosen are severely biased by the selection
      process that, for whatever reasons, eliminated most of the
      potential cases; and d) the controls have a similar selection
      bias. In addition, the methodology used for the statistical
      analysis (“conditional logistic regression”) is a
      problematic choice as are the stratification into unbalanced
      groups (ASD, AD, and ASD with regression) and unbalanced
      percentages from the 3 HMOS used.

      4. With respect to your:
      “This, if anyone, goes against the mercury hypothesis, as
      it suggests younger autistic children clear mercury faster
      or have lower exposure. If mercury causes autism then the
      higher level should occur when younger – before the onset
      of autism”,
      the realities are:
      a. Because the doses were “matched” all got about the same
      dose of mercury.
      b. The level of mercury in the hair “is a measure of” the
      amount of mercury that is being excreted — it is NOT a
      measure of exposure.
      c. Based on other studies and this one those that get
      “autism” excrete less of the mercury with which they
      are dosed than those who do not get autism.
      d. Since the vaccine-mercury exposure stopped, the older
      “mathced control” children who had excreted much more
      of the mercury dose than the older “case” children had
      lower levels of hair mercury and the “older” case
      children who had higher level because they were still
      excreting the mercury from their early childhood mercury
      (Thimerosal)-preserved vaccines that they had been
      Hopefully, after reading the preceding and studying the
      paper, you will see these realities or continue to live
      in denial — the choice is yours, NOT mine.

      5. With respect to your:
      “However – I think this is just a small study with random
      results, and probably not real. Other studies show no
      please provide me with: a) the other studies where the
      dosing and the subjects (cases and matched controls) are
      truly this well matched or better matched, and b) the
      statistical probability values for the correlations are
      better than, for example, those found in Table III:

      Autistic (M+F) Controls (M+F)
      Groups I + II Groups I + II p
      complications (%) 20.4* 6.5 p=0.009
      development (%) 40.9* 3.9 p<0.001

      Given thes probability values and the meticulous matching
      of the case children and the "matched control" children in
      the Polish study, it is clear that the findings CANNOT
      rationally be contributed to chance as you have done. Nor,
      if you understand the power of studies where the cases are
      truly matched by suitable controls as meticulously as done
      here, are 91 cases and 75 matched controls a small study.

      5. In light of the preceding realities, I leave it to you to
      reflect upon your last statement — which is clearly at
      odds with the facts on many levels.

  11. Mario says:

    soo sad that so many MD’s keep regurgitating soo much confusion about this topic, just look at Latinamerica and Africa we have been using thimerosal and the cheapest vaccines for many years, because we can’t afford other options, and the social conditions in our countries are worst than Europe or US yet the incidence of Autism has been in steady state for years, at the end of the day you will believe what you want to but the sad part is that people that have the power to influence others can’t put aside their beliefs and stick to the facts….we can’t pay for the vaccines but we want them, you can pay for them but you don’t want them.

  12. Tom says:

    Dear Paul King:

    If the poor excretor hypothesis were correct, these children would be autistic because of the far greater mercury exposure they receive from living on the planet than from the miniscule amount of thimerosal in vaccines (especially now that it’s been removed from vaccines). The poor excretor hypothesis means autism would be unavoidable and so vaccinating these autistic children from avoidable diseases that kill and maim would be the correct course.

    Besides, mercury poisoning is not autism.

  13. All who clamor at my door,

    Those of you who provide no substantiation to the validity of your remarks or a single source of substantiation without proof of its validity are only “speaking to hear yourselves heard” so, if any of you are really interested in the supporting studies for the statement I have made for which no study was cited, please find them yourselves.

    For those who, with no scientific evidence (not “evidence-based consensus speak”)to support your position, seek to preclude the use of any peer-reviewed article for which no credible independent study has been able to refute its findings, I am content to follow the Christian reminder about where not to speak the scientific truths as, based on a thorough and ongoing study of the evidence, I currently know them to be.

    Finally, as Dr. Novella is well aware, if you can find and provide credible peer-reviewed studies that are not diectly or indirectly controlled or influenced by the US governmental agencies or the drug companies, that invalidate the science as I now understand it, I will revise my science-based views accordingly.

    Hopefully, except for those whose egos demand the last word, this response will end the discussion of my comments EXCEPT as stipulated in the previous remark.

    • Chris says:

      You were asked to provide documentation for your assertions. Since this is your answer we can now assume you have none. At least very few not by the Geiers.

      Also, who do you think should pay for studies if not “US governmental agencies or the drug companies”? Do you think that the studies out of Japan, UK, Finland, Germany, Denmark, Sweden and Canada more valid?

      So are most autistic children born to women who have had RhoGAM? Please link to the PubMed article.

    • Chris says:

      Oh, my!

      Oh, no!

      None of the rest are physicians, although one is a Ph.D. analytical chemist, who also really should know better, at least about the Geiers’ claims about testosterone and mercury…. Of course, being a chemist, he may have no clue about the rest of the motherlode of autism woo on the Geiers’ website.

    • steelsheen11b says:

      Mr. PHD you’re backed into a corner and are playing the “big” pharma/Gov card? Sad but predictable behavior just like you’re mistaking wordiness for intelligence.

  14. Chris says:

    Paul King, PhD:

    if any of you are really interested in the supporting studies for the statement I have made for which no study was cited, please find them yourselves.

    So a search on PubMed for “rhogam autism” brings up a total of eight papers (list provided at end of this message). One by Mr. Blaxill (and friends), who has no science background, and a few by the Geiers. The remaining ones are comments on their papers by real scientists. They don’t seem to think that RhoGAM causes autism, and apparently neither does the federal court system.

    Now the big question for Dr. King is: Do you support the chemical castration of autistic children?

    List from PubMed search using the words “rhogam autism”:

    Prenatal exposure to anti-D immune globulin and autism risk: Croen et al.
    DeFranco E, Gross G, Shanks A, Johnson T, Shen T.
    Am J Obstet Gynecol. 2008 Sep;199(3):322-3. No abstract available. PMID: 18772000 [PubMed - indexed for MEDLINE]Related citations

    Discussion: Prenatal exposure to anti-D immune globulin and autism risk by Croen et al.
    DeFranco E, Gross G, Shanks A, Johnson T, Shen T.
    Am J Obstet Gynecol. 2008 Sep;199(3):e1-4. No abstract available. PMID: 18771966 [PubMed - indexed for MEDLINE]Related citations

    Maternal Rh D status, anti-D immune globulin exposure during pregnancy, and risk of autism spectrum disorders.
    Croen LA, Matevia M, Yoshida CK, Grether JK.
    Am J Obstet Gynecol. 2008 Sep;199(3):234.e1-6. Epub 2008 Jun 13.PMID: 18554566 [PubMed - indexed for MEDLINE]Related citations

    Neurodevelopmental disorders, maternal Rh-negativity, and Rho(D) immune globulins: a multi-center assessment.
    Geier DA, Mumper E, Gladfelter B, Coleman L, Geier MR.
    Neuro Endocrinol Lett. 2008 Apr;29(2):272-80.PMID: 18404135 [PubMed - indexed for MEDLINE]Related citations

    Re: Miles & Takahashi paper on RhIg and autism.
    Bernard S, Blaxill M, Redwood L.
    Am J Med Genet A. 2008 Feb 1;146(3):405-6; author reply 407. No abstract available. PMID: 18074377 [PubMed - indexed for MEDLINE]Related citations

    A prospective study of thimerosal-containing Rho(D)-immune globulin administration as a risk factor for autistic disorders.
    Geier DA, Geier MR.
    J Matern Fetal Neonatal Med. 2007 May;20(5):385-90.PMID: 17674242 [PubMed - indexed for MEDLINE]Related citations

    Lack of association between Rh status, Rh immune globulin in pregnancy and autism.
    Miles JH, Takahashi TN.
    Am J Med Genet A. 2007 Jul 1;143A(13):1397-407.PMID: 17508426 [PubMed - indexed for MEDLINE]Related citations

    A case series of children with apparent mercury toxic encephalopathies manifesting with clinical symptoms of regressive autistic disorders.
    Geier DA, Geier MR.
    J Toxicol Environ Health A. 2007 May 15;70(10):837-51.PMID: 17454560 [PubMed - indexed for MEDLINE]Related citations

  15. Do'C says:

    It found that, the younger children excreted less of the mercury dose they had received compared to the children in the younger-children MATCHED control group.

    Incorrect. The study only measured hair mercury concentration. It did not quantify or qualify “excretion” in general, nor did quantify or qualify mercury dose, other than from vaccinations, (such as diet and environment).

    4. With respect to your:
    “This, if anyone, goes against the mercury hypothesis, as it suggests younger autistic children clear mercury faster or have lower exposure. If mercury causes autism then the higher level should occur when younger – before the onset of autism”, the realities are:

    a. Because the doses were “matched” all got about the same dose of mercury.

    Incorrect, and the authors acknowledge this in the limitations:

    “The weaknesses include inability to assess more accurately the sources of mercury exposure and non-uniform selection of study participants: controls were from one geographic region, while autistic patients were from more diverse regions of Poland.”

    b. The level of mercury in the hair “is a measure of” the amount of mercury that is being excreted — it is NOT a measure of exposure.

    Epic Fail. The level of mercury in the hair is a measure of the amount of mercury that was circulating in the blood at the time the hair was formed. As a proxy for excretion in general, actual general excretion data would be required.

    c. Based on other studies and this one those that get “autism” excrete less of the mercury with which they are dosed than those who do not get autism.

    Epic Fail. Data-free acceptance of the Holmes et al. *hypothesis* (that lower hair levels of mercury might signify lower excretion, IF hair elimination is related to excretion in general) is a common pifall for those who’ve latched on to the idea that lower hair levels of mercury mean lower mercury excretion in general. In fact, the opposite has real scientific support. Hair mercury levels are higher with acutal impaired excretion – Gundacker et al. 2007

    “RESULTS: The following was noted: a) hair mercury concentrations are significantly increased in persons with the double deleted genotype (GSTT1-/- and GSTM1-/-) as compared to persons with the intact genotype, and b) MT1X expression is higher in persons with the intact genotype (GSTT1+/+ and GSTM1+/+).”

    d. Since the vaccine-mercury exposure stopped, the older “mathced control” children who had excreted much more of the mercury dose than the older “case” children had lower levels of hair mercury and the “older” case children who had higher level because they were still excreting the mercury from their early childhood mercury (Thimerosal)-preserved vaccines that they had been given.

    This assumes that vaccine-mercury exposure is the primary influence without evidence that it is. It assumes that hair mercury levels correlate with excretion – they don’t, they vary inversely (impaired excretion results in higher levels of hair mercury).

    The authors of Majewska et al. also apparently fall into the trap of thinking the 2003 hypothesis of Holmes et al. is a notion with any validity.

    “Our data seem consistent with the notion that young autistic children might be poor eliminators of heavy metals – hence showing lower mercury levels in the hair – but may retain greater amounts of mercury in their body tissues, including the brain (Holmes et al. 2003, Adams et al. 2007, 2008).”

    Gundacker et al. 2007 shows us that the notion was ill-conceived, but Holmes et al. were careful to preface their hypothesis with a giant “IF”. It’s a shame some “reasearchers” don’t get that. Holmes et al. generated a failed hypothesis, it didn’t establish anything. It’s also a shame that some very basic biology seems to be ignored. Lower hair mercury levels do relflect lower exposure to the brain at the time the hair was formed.

  16. Bab says:

    It is very unfortunate that a few people, like Dr. Paul King (who is not an M.D), and the Dr. Greier brothers, all have CONSIDERABLE conflicts of interst as they are selling treatments for autism for thousands of dollars. It is amazing how just a few voices with a monetary motive can continue to keep the entire population skeptical about vaccinations.

  17. SKepticmyAss says:

    You have obviously been drinking lately or are on the Pharma payroll. This is not some mass dillusion instead a well financed coverup. Unfortunately you are part of the propaganda machine hiding the truth.