I know you are, but what am I?

Denialism. You keep using that word. I do not think it means what you think it means.

The story might be apocryphal, and it might not even be true, but it’s often used as a metaphor. I’m referring to the “boiling frog” story. Basically, the idea is supposedly based on an observation that a frog, when placed in a pot of hot water, will immediately jump out. However, or so the story goes, if the frog is placed in room temperature water and the water is heated gradually enough, the frog won’t notice and will eventually boil to death without trying to escape. The metaphor, of course, is designed to illustrate how people will almost always notice rapid change, but, if the change is sufficiently slow, might not notice it at all and will readily acclimate themselves to the new situation if given sufficient time. Of course, the phenomenon underlying this metaphor might very well not even be real, but it’s still probably a useful metaphor.

Being in the skeptic movement and having been very active over the last seven years blogging about skepticism, promoting science-based medicine, and combatting the antivaccine movement, this metaphor might be the reason why I didn’t notice a particular tactic being increasingly used by denialists of all stripes until relatively recently, which is also relatively late. It took Mark Hoofnagle, who had disappeared from the skeptical blogging front for a couple of years pursuing his general surgery residency, to be slapped in the face with it and comment to me that he had been noticing this phenomenon upon returning to blogging about science denialism on his very own denialism blog. He was right, but in fact denialists had been doing this for a long time, and it was only a shock to Mark because he had stopped paying attention for a while and then was, like the proverbial frog, thrown back into the water.

Part of what led me to think about this phenomenon was a doozy of a post published on–where else?–that wretched hive of scum and quackery (no, not The Huffington Post–I mean that other wretched hive of scum and quackery), the antivaccine crank blog extraordinaire, Age of Autism. The post is by someone whose name is not familiar to me as one of the regulars, Cathy Nevison, and entitled Autism and the Antarctic Ozone Hole. Yes, in this post, Nevison does exactly what the title implies and tries to liken “autism epidemic denialists” to anthropogenic global warming denialists. Before I delve into the numerous deficiencies in Nevision’s crank arguments, I do have to pause to express amusement about a passage right in the first paragraph:

A recent Associated Press report that 1 in 88 American children has an autism spectrum disorder (ASD) asserts that, “Better diagnosis is largely responsible for the new estimate…” Another AP report, on a study finding that 1 in 38 South Korean children has an ASD, quotes the lead author as saying, “It doesn’t mean all of a sudden there are more new children with ASDs. They’ve been there all along, but were not counted in previous prevalence studies.” These are extraordinary claims and examples of autism epidemic denial. Equally remarkable is that the AP presents them as unquestioned truth, making no effort to counter them with dissenting viewpoints. In contrast, the media has been diligent about “balancing” articles on the threat of climate change with opposing views from “climate skeptics,” which has contributed to climate change denial.

I rather suspect that the irony escapes Dr. Nevison here. For one thing, it’s unclear what side she is on in the climate change manufactroversy. She seems to lament that the media seems to accept statements from scientists that there is no autism epidemic, that the increased prevalence is due to factors like diagnostic substitution, broadening of the diagnostic criteria, and more intensive screening without presenting opposing viewpoints. Personally, I wonder what planet she’s living on, because most of the stories I’ve seen about, for example, the CDC report that pegs the prevalence of ASDs at 1 in 88 took the number at face value and made little effort to explain that this new estimate of prevalence doesn’t necessarily mean that the true prevalence has increased. What I’ve tended to see is reporters taking the 1 in 88 figure and using it to allow speculation over what’s causing it, in particular environmental factors.

Be that as it may, if we follow Nevison’s simile, she appears to be likening “dissenting viewpoints” on the autism “epidemic” (i.e., the antivaccinationists who believe this is a real increase in prevalence and blame it on “environment”–cough, cough vaccines) with “climate skeptics” who contribute to climate change denial. I rather suspect that that is not exactly the comparison that Nevison wanted to make, but it’s a very apt one. Antivaccinationists are very much like AGW denialists in that they deny the overwhelming weight of evidence to insist upon a belief that evidence does not support. The message seems to be that, because Nevison approves of “telling both sides” of the story with respect to the increase in autism prevalence where once side is based on pseudoscience (i.e., antivaccinationism), then she would also approve of telling the AGW side.

Nevison, who is apparently some sort of atmospheric research scientist at the University of Colorado then dives into a seriously tortured comparison between the ozone hole over the Antarctic and autism. You can read it in all its twisting glory for yourself, or allow me to try to summarize. Basically, Nevison points out that a hole in the Antarctic ozone layer first occurred in the 1980s due to human release of chlorofluorocarbons (CFCs) and other halocarbons. It turns out that the reason that the ozone hole over the Antarctic appeared there because of the extreme cold, which allowed the formation of polar stratospheric clouds (PSCs), and it’s on the surface of these clouds that the chlorine and bromine are released from CFCs as reactive ozone-destroying compounds. I didn’t delve too deeply into this. I assume that an atmospheric scientist probably knows what she’s talking about when it comes to ozone depletion. On the other hand, given the whoppers about autism and vaccines that follow, maybe I shouldn’t assume too much about Nevison’s scientific acumen.

To boil her message down to its essence, Nevison identifies CFCs as the cause of ozone depletion (correct) and the cold in the Antarctic as a “predisposing factor” that allowed the hole to form in response to CFC emission. Given that explanation, I bet you can see where her analogy is going, and it doesn’t take her long to go there:

The relevant point is this: while one can say with some accuracy that the ozone hole occurs because Antarctica is cold, the pre-1980s ozone layer over the continent was perfectly adequate at blocking harmful UV radiation. It was only with the accumulation of CFCs in the atmosphere, reaching dangerous levels by the 1980s, that the extreme cold over Antarctica became a threat to ozone. By distinguishing between the actual trigger for the ozone hole (CFC production and release to the atmosphere), which are within human control, and the predisposing factors (naturally cold temperatures), which are not, the international community was able to identify the cause of the problem and take decisive steps to end it.

Which leads to the analogy you knew she was going to make:

If atmospheric scientists had adopted the approach of many in the autism research community, Antarctic ozone column measurements prior to the 1980s would have been forgotten, leading the scientists to declare that the ozone hole had “been there all along.” Obvious clues, such as the elevated levels of reactive chlorine measured in the hole, would have been dismissed as pure coincidence. Believing the springtime hole to be a natural and unpreventable phenomenon, the scientists would have focused their efforts on early detection, enabling them to warn visitors to Antarctica to use sun protection. Statistical correlations between temperature and ozone would have led the scientists to note that cold temperatures increased the odds ratio of having an ozone hole. In short, the scientists would have concluded that the ozone hole occurs because Antarctica is cold.

Nevison concedes (reluctantly, I would guess) that what she refers to as “overvaccination” (a typical antivaccinationist term that is undefined) is “unlikely to be the only factor involved in the autism epidemic” because if it were she would expect the epidemiology to give a clearer result. However, even with her concession, Nevison’s analogy is clearly that vaccines and some other factors are the real cause of the “autism epidemic” and that scientists and epidemiologists are somehow mistaking something else for the cause the way she claims it would be possible for someone to conclude that cold temperatures were responsible for ozone depletion over the Antarctic. She goes on about how the CDC supposedly cuts off autism prevalence rates at a birth year of 1992 in order to hide a lower prevalence rate before 1992. Amusingly, she even cites some truly horrendous research that claims to have found that there was an inflection point in 1988 in which the rate of increase of autism took a sudden uptick. It’s a horrible study that I blogged about when it came out. At least, I think that’s the study Nevison is citing. She doesn’t provide a citation or a link, but the description fits.

In any case, Nevison makes the truly brain dead argument that scientists are so stupid or ignorant that:

Again, the distinction is not made between predisposing risk factors and actual causes. Pertinent questions such as, was there a dramatic increase in maternal obesity in 1988?, are not asked, even as absurd pronouncements that 1 to 3 percent of children have always been autistic go unchallenged in the popular press.

Of course, trying to distinguish between predisposing risk factors and actual causes is what epidemiologists, public health officials, and doctors try to do. If I were an epidemiologist I would be profoundly insulted that someone like Nevison apparently thinks my profession is so incompetent that it could so easily (and apparently willfully) confuse such things. Her argument that going from a prevalence of 1 in 2,500 to a prevalence of 1 in 88 is impossible without some sort of cause (like vaccines, apparently) reveals a profound ignorance of medicine, too. I pointed out in depth why it is in fact very possible for screening alone to result in rapid increases in prevalence, using the examples of ductal carcinoma in situ (DCIS), hypercholesterolemia, hypertension, and other conditions.

Just to pick one of them (DCIS, because I’m a breast surgeon) and at the risk of repeating myself too closely, I’ll point out again that back in the early 1900s, DCIS was fairly uncommon because by the time a DCIS lesion grew large enough to be a palpable mass, it almost always had become invasive cancer. Then, back in the 1970s and 1980s, widespread mammographic screening was introduced. Now, 30 years later, DCIS is very common, making up approximately 40% of breast cancer diagnoses. I’ll even point out that a recent study suggested that DCIS incidence rose from 1.87 per 100,000 in the mid-1970s to 32.5 in 2004. That’s a more than 16-fold increase over 30 years, and it’s pretty much all due to the introduction of mammographic screening. So it’s not at all inconceivable that a combination of widened diagnostic criteria, more screening, and higher awareness could cause the apparent prevalence of ASDs to increase 25-fold in 20 years. It might be that there has been a true increase in autism prevalence, but the evidence is fairly clear that there is not an “autism epidemic.” Of course, the antivaccine movement needs the “autism epidemic.” It needs it because if it can’t convince people that there is such an “epidemic,” than the central argument for its promotion of a vaccine-autism link collapses. If autism prevalence hasn’t been skyrocketing in a way that correlates with the increase in the number of vaccines in the recommended schedule over the last 25 years, then that’s pretty powerful epidemiological evidence that vaccines do not cause autism. Of course, we don’t actually need such evidence, given that we have numerous studies that have failed to find, as I like to say, a whiff of a hint of a whisper of a link between vaccines and autism, but antivaccinationists will never admit that.

Nor will an atmospheric scientist, apparently, admit that.

Of course, Nevison is not the first to try to draw an analogy between denialism of other scientific findings and the vaccine-autism link. In fact, she was rather more subtle than most in that she only mentioned the analogy once in her post before launching into her embarrassing analogy. Others like to try to pound the fallacious analogy home, hitting readers over the head with the proverbial brick, so to speak. Dr. Jay Gordon, for instance, was probably the first person I noticed doing that when he tried to liken vaccine manufacturers to tobacco companies. Yes, he didn’t use the word “denialist,” but his intent was clear, to liken vaccine proponents to the denialist tactics that tobacco companies used to try to deny that cigarettes caused cancer. Meanwhile, other antivaccinationists have taken to calling scientists “vaccine injury denialists.” Even Dana Ullman, everybody’s favorite loopy homeopath, is getting in on the act, referring to those who point out the extreme scientific implausibility of homeopathy as “denialists.”

I have a word of advice for Dr. Nevison. Stick to atmospheric science. You clearly don’t understand medicine or epidemiology, and I hate to see you embarrass yourself any more than you already have by making an incoherent analogy to climate change denialism to support your antivaccine views and then coupling that analogy to an even more incoherent analogy between ozone holes and the “autism epidemic.”