May 01 2007

Another Salvo in the Mercury/Autism Controversy

There are many true controversies within science – where the evidence is not definitive competing theories may remain plausible and their proponents will fight hard for them. Ideally, this scientific fighting will lead to new ideas and new evidence that will eventually resolve the controversy. But most of the scientific controversies that garner public attention are fake controversies – they are not disagreements among serious scientists but between the mainstream scientific consensus and a dedicated group of unscientific ideologues working hard to subvert science to their cause. Evolution vs creationism is a good example of such a fake controversy, as is the denial that HIV causes AIDS. Another is the controversy over whether or not mercury, and specifically the mercury-containing vaccine preservative thimerosal, causes autism. The scientific consensus forming around a large body of evidence is pretty solid – no! Vaccines do not cause autism.

Yet there exists a largely grassroots movement that insists mercury/thimerosal does cause autism. Their beliefs are born largely by desperation, as the ranks of such groups are filled by parents of ASD children. They are ideologically fueled by anti-establishment, anti-government, and anti-corporate conspiracy thinking. They have their champions in the guise of activists like Robert Kennedy, journalists like David Kirby, and rogue scientists like the father and son Geier team.

I have thoroughly examined the evidence and claims in this article I wrote a couple of years ago. I won’t repeat them here – for background please read my prior article. There is a minor update on the evidence. In 2001 thimerosal was removed from single-dose childhood vaccines in the US. You would therefore predict (and in fact David Kirby in an interview with me agreed to this prediction) that autism rates would begin to drop. It hasn’t. This is the final proof that thimerosal does not cause autism. This is also a standard form of evidence in medicine – remove a putative cause and if the disease does not go away, the putative cause is not the cause of the disease.

The mercury believers have not relented, however. They say that although thimerosal was removed from new vaccines, old vaccines were not recalled. We have no way of knowing, they argue, for how much longer doctors used the thimerosal-containing vaccines in their supplies. True, but this argument is rapidly fading. First, the percentage of vaccines with thimerosal began declining the moment the preservative was removed from new vaccines, and should continue to decline, eventually reaching zero. It also takes about three years for autism to manifest, so this is also a delay. Well now it is 6 years later. We should have seen some decline by now. But so far the evidence shows a continued rise in autism rates. The mercury proponents rationalizations are rapidly going from weak to absurd. In another year or two they will need to start inventing some new excuses. I can’t wait to hear what they come up with. Maybe they will surprise me and admit thimerosal does not cause autism – one can always be hopeful.

Now I am happy to report on an editorial published in Nature Neuroscience. The journal, part of the prestigious Nature publishing group, boldly asserts what scientists already know – that mercury and vaccines do not cause autism. But further, it exhorts scientists to remain in the public controversy. This may seem strange – aren’t scientists in the business of advocating for scientific evidence? The editorial reflects a very disturbing fact – the mercury causes autism crusaders have been successful in intimidating the scientific community into relative silence.

Orac over at Respectful Insolence has nicely summarized the situation. I will only add my personal anecdote. In researching my prior paper I encountered a couple of autism scientists who did not want their names referenced in my article. The reason was that they did not want to invite harassment by the mercury crusaders. It was just too much trouble, and not worth it, they reasoned. From their perspective they were busy doing science and communicating to other scientists. The mercury-autism crowd were a bunch of crazies not worth dealing with – they were best avoided.

Unfortunately the result is that the crazies are raising a frenzied din that is getting the attention of the media and may even be affecting public policy, while the scientists who know better are cowed into avoidance.

The editorial, echoed by Orac, and now by me, calls for the scientific community to stand tall. We need to unite under the banner of science and reason, to affirm that modern medicine is an applied science, that good medicine follows the best evidence available and relies upon valid logic.

I will also extend the call to all of so-called complementary and alternative medicine (CAM). CAM is nothing less than an assault on the scientific underpinnings of modern medicine. It is an eclectic collection of anti-scientific ideology, new age nonsense, bad science, and discarded notions. It survives by political intimidation, the ad-populi logical fallacy, a misapplication of multi-culturalism and “open mindedness”, anti-establishment sentiment, misplaced appeals to freedom, fraud, cons, slick marketing, wishful thinking, scientific illiteracy, and blatant anti-science. The goal of CAM advocates is to create a double standard within medicine – a standard for them in which all of the quality control of evidence, academic and intellectual honesty, and even basic common sense do not apply.

The medical community has been shamefully silent, sitting on the sidelines while their own profession is ransacked by barbarians. The beginning of a backlash is stirring, but it’s too little and too late. The damage to the credibility and scientific integrity of mainstream medicine will be significant and long term.

As an aside, when I write about such issues I often feel that I come off sounding shrill, and that bothers me. My dilemma is that I feel about CAM what evolutionary scientists feel about creationism/ID. The challenge when criticizing creationism is to find language that is strong enough to capture the abomination of science that it is. But in so doing one sacrifices the detached and neutral tones more typical of science. So I try to compromise, being direct, firm, uncompromising, but also calm and impersonal. I am still working on finding the rhetorical sweet-spot – being stirring and inspiring while coming off as cool and professional. I guess I’ll keep working on it.

Meanwhile, I will take the Nature Neuroscience article as a minor victory in a subset of the broader struggle.

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