New Study Says No Vaccines-Autism Link

Via Autism Diva I learn of this study just published in the journal Pediatrics. The objective of the study was to estimate the prevalence of pervasive developmental disorder (PDD), which includes autism, and compare this with cumulative exposure to both thimerosal and MMR vaccines. The authors surveyed 28,000 children born from 1987 to 1998. Children with PDD were identified by a special needs team.

What they actually found was that children who had had no exposure to thimerosal actually had a higher degree of PDD. No association to PDD was found with the MMR vaccine. From the abstract (all quotes are with my bold):

The prevalence of pervasive developmental disorder in thimerosal free birth cohorts was significantly higher than that in thimerosal-exposed cohorts (82.7 of 10 000 vs 59.5 of 10 000). Using logistic regression models of the prevalence data, we found no significant effect of thimerosal exposure used either as a continuous or a categorical variable. Thus, thimerosal exposure was unrelated to the increasing trend in pervasive developmental disorder prevalence.

The authors conclude that the increased prevalence of PDD is due to broadening diagnostic criteria and increased awareness. If you remember, this is the explanation that Bobby Kennedy called “a theory that seems questionable at best, given that most of the new cases of autism are clustered within a single generation of children”. Well, it’s hard to see what other conclusion could be drawn from this study. From the paper again:

During the 12 years encompassed by our study, thimerosal exposure before age 2 of each birth cohort changed several times and ranged from nil to a high value of 225 μg. This provided a unique opportunity to test the relationship of ethylmercury exposure with rates of PDDs, free of a known problem of vaccine safety studies when high rates of exposure in populations, and therefore low variability in exposure, constrain the data and limit the opportunity to detect effects.⁶³ No association between thimerosal levels treated either continuously or categorically with PDD rates could be found in our study. In fact, it was remarkable that the PDD rates were at their highest value in birth cohorts that were thimerosal free, providing a clear and convincing message on the lack of an association. The results were robust and held true when various analyses were conducted to evaluate the potential impact of misclassification on exposure and diagnosis. Within each period of medium, high, or nil exposure, the same trend toward a steady increase in PDD rate was observed, demonstrating total independence of the 2 variables.

The authors also address one of the mercury-causes-autism lobby’s criticisms of other studies that have also shown no link, namely that these other studies were in countries with lower exposure to thimerosal or lower rates of PDD:

Previous negative studies, especially those conducted in European countries, have sometimes been criticized on the account that either the rates of PDDs were not as high as those in North America, that the cumulative exposure to thimerosal was much lower than that attained in the United States in the 1990s, or both. This study avoids both pitfalls and is, therefore, very informative for the North American public. In addition, the rate of exposure varied from nil to very high levels of vaccine-derived ethylmercury, allowing us to test for effects along the full range of exposure and to detect possible threshold effects as well. All of the results were negative.

Of course, don’t expect this study to convince the religious mercury-causes-autism groups. From a (pretty good) BBC article on the study we find:

Jackie Fletcher, from campaign group Jabs, a support network for parents who believe their children have been damaged by vaccines, said the study still did not prove there was not a link.

Well, proving a universal negative is always difficult, but with one more seemingly well run study finding no link when you would expect to find one if it were there, haven’t we passed the point when it becomes perverse to insist there is a link?

Edited to add:

Two more excellent reads today on this subject. Respectful Insolence has a more detailed write-up about this study, along with an examination of some of the usual smear tactics used by the mercury-causes-autism group SafeMinds. Left Brain/Right Brain has a further perspective on SafeMinds hypocritical ad hominems, and insight on where they might be headed in their future mercury claims.

Comments

[Diana]

Hmm... OK, I can accept that mercury doesn't cause autism.

But, mercury is still poisonous. I really can't blame anyone for not wanting it injected into them or their children, even if autism isn't one of the potential negative effects.

If pro-mercury-injection people want to soothe parents, etc., they should probably find some way to explain to people why these mercury injections are not harmful.

I don't know enough about these injections to feel confident believing anything about them for certain.

But, I am inclined to be quite leery of them, since mercury is definitely poisonous, and it seems very commonsense to not want it injected into you or a loved one.

Best wishes. :)

[BronzeDog]

Mercury is poisonous. Ethyl mercury, one of the chemicals thimerosal breaks down into is not (at least, not in the amounts given) for the same reason that water isn't flammible (hydrogen), and table salt isn't a poisonous green gas (chlorine): The woos, especially Fore Sam, love to obscure that little grade school chunk of chemistry by referring to compounds as their least favorite element.

Additionally, the dose makes the poison: Even oxygen can be poisonous.

Of course, woos have been taking the trend towards removing thimerosal as proof of teh ev1l gl0balist conspiracy cover-up. If it remained, they'd be claiming it's for vaccine manufacturers to maximize profits. Can't please anyone.

Additionally, even if all the thimerosal was removed yesterday, they'd continue to blame it, or they'd shift to blaming something else in vaccines. Just watch what happens if you tell one of them that MMR never had thimerosal in it.

[HCN]

On the same premise... yes, if you spill mercury and breath the fumes, it is dangerous.

Also you will burn your lungs with chlorine gas, and sodium is a very volutile metal (it you throw it into water it explodes and burns). But you cannot live without common table salt: NaCl (sodium chloride).

Also, the elements hydrogen, carbon and nitrogen are generally considered harmless... except as hydrogen cyanide, HCN. (though several scammers try to sell laetrile, which they also call vitamin B17, to cure cancer, but forget to tell folks that the active ingredient is HCN).

For more information on the history of the use of thimerosal and the actual amounts in vaccines see:
http://www.fda.gov/CBER/vaccine/thimerosal.htm
(also think about what you would rather have during a natural disaster: a DT shot with thimerosal to keep bacterial infections out of the multi-dose vial, a DT shot without thimerosal which may not have been stored properly because of power interruptions... or the actual tetanus disease).

[michelle]

Mercury is poisonous in certain doses, but measles, mumps, rubella, polio, etc tend to by far deadlier. Lets not forget about the obscene amount of mercury in tuna and other large fish...

I would be far more concerned for the child that eats a tuna sandwhich 3 times a week.

[Nathan D]

The study was done in one specific geographic region -- the folks I have heard complaining about mercury and such in vaccines tend to focus on California -- there was some level of geographic specificity, at least. Of course, none of it caused us to not have our kid vaccinated, but just worth pointing out that you can't use this one study to dismiss the argument if the argument is about different vaccines than those used in Quebec during the period studied.

[Skeptico]

Nathan

Re: you can't use this one study to dismiss the argument if the argument is about different vaccines than those used in Quebec during the period studied.

Your point is incoherent:

1 Thimerosal is Thimerosal – it’s the same whether it is in a vaccine given in Canada or California.

2 PDD rates were highest when the children were Thimerosal free. That is true no matter what vaccines are being used elsewhere. That indicates Thimerosal is unlikely to be to blame.

3 What are you suggesting is in the vaccine in California that is to blame? And how could this, if it is not in a vaccine in Canada, be causing this high rate of PDD in Canada?

[HCN]

Also, Nathan... There are also population studies that have taken place in the UK, Finland, Denmark and the State of Washington that all came to the same conclusion.

These are referenced in the full paper:
http://pediatrics.aappublications.org/cgi/content/full/118/1/e139

Also, information on California is also listed in the bibliography.

[Mia Gahdus]

Mercury/thimerosal was NEVER used in the MMR vaccines, as it would kill the live virus used.

It is the aluminum and formaldehyde that causes the most damage, as both are proven neurotoxins. Both are found in many of the vaccines.

[BronzeDog]

Last time I checked, aluminum was fairly inert inside a human body.

Formaldehyde is a new one on me. Do you have evidence that it's toxic in the amounts given?

After all, everything's a neurotoxin in high enough amounts.

[Big Al]

Aluminium has neurotoxic effects in large enough doses (can bring on Alzheimer's), but I think you need a fairly large single dose.

Formaldehyde is slightly carcinogenic, but I think you need to be in skin contact with it for many prolonged periods.

I know these facts, and I'm not a physician or clinician. I imagine the people who produce the vaccines know the danger criteria in infinitely better detail than I.

I suspect the real problem is not thimoseral, aluminium or formaldehyde. Doubtless these vaccines are suspended in water at some stage; pure, sterile water. Autism must be caused by homeopathic overdose!

Ban all sterile water immediately!