by Carl V Phillips
Because trying to have a discussion on Twitter is not a clever thing to do, and I like to stop doing unclever things when I catch myself at it, here is a Q-and-A format (most of the Qs are not really questions, but I will just call them that). If you have a Q or an A that is missing, leave it in the comments and I will update the post.
My tweet that started my ill-advised foray in trying to discuss via twitter:
Your periodic reminder: if vaping is really 95% less harmful than smoking, as many vehemently claim, then it is really quite bad for you.
Background: This specific point estimate (synonymous with “5% as bad for you as smoking”) has rapidly evolved into “fact” (in the political sense of that term). It is repeated in a large fraction of popular press reports and widely used in arguments, snipes, and broadsides from vaping advocates. It seems to have emerged from nowhere when the Public Health England report asserted the figure. That traced to what was actually a huge misinterpretation of what was only a made-up number, from one junk-science journal article. When called on this, the PHE authors denied that was the source of the number, though they did not offer an alternative basis for the number and they did cite that paper originally, so the protest was not exactly convincing. I have documented all of that on this page in detail.
If the figure were true, it would put vaping very high up the list of “something a lot of people choose to do that is bad for their health”. That is particularly true if you accept tobacco control’s inflated claims about the effects of smoking (which most of those making the present claim endorse), but still true if you base it on an honest estimate of the risks from smoking. Vaping would be worse than eating a pretty bad diet rather than an ideal diet. It would be worse than never getting any health screening test. It would be many multiples of the risk from smokeless tobacco. It would be worse (for the individual) than forgoing most vaccines. In other words, if someone has the “public health” mindset that it is ethical and socially acceptable to dictate people’s health affecting choices, this figure puts vaping near the top of the list of activities that warrant action (i.e., aggressive denigration, misinformation campaigns, bans — you know the drill).
Is this an accident? Perhaps, but that is far from obvious to me. Notice that the 95% claim was made up and touted by pro-ecig tobacco controllers. For them it is the perfect sweet spot, which makes it seems like less of an accident: It is low enough to clearly justify their efforts to promote vaping as a “cure” for smoking. But it is plenty high enough to justify trying to prevent vaping or to promote vaping cessation for anyone who does not “need” it to avoid smoking. It offers a very nice political compromise with their colleagues and funders who they are answerable to (the offer has been rebuffed so far, but sits there as a way to get to yes): Stop screwing up our attempts to, um, persuade smokers to switch to vaping, and we will back your position that vaping should be avoided by anyone who is not using it to quit smoking; in a few years, after vaping-assisted smoking cessation has pretty much played out, we will be on the same side again.
But whether or not that suspicion is valid, the point estimate of 5% the risk from smoking is way higher than what the science supports.
Question: That is why we say “at least 95% less harmful”.
Answer: First, that is mostly not true. Most statements I have seen do not include “at least”. Second, saying that does not matter. Basically everyone who gives me crap about arguing for scientific honesty justifies their behavior based on needing to say what is effective, regardless of what is true. Setting aside the ethics and long-term tactical implications of saying whatever seems to be most effective, if that is your position, you need to learn something about how people respond to particular statements. In particular, when people see “at least 95%”, most of them just think and remember “95%”.
Third, such a statement is clearly scientific nonsense. Whatever the best point estimate is, there is no “at least”. This is fundamentally true for all science. Such a statement is tantamount to saying there is no evidence that could appear tomorrow that would push the estimate beyond the stated bound, which is the mindset of religion, not science. But in this case, it is not even a matter of fundamentals. We do not have any epidemiologic evidence that would let us rule out risks greater than that. There is a reasonable chance that we will never have such evidence.
Question: But the more recent Royal College of Physicians report has all that covered. They make various versions of the statement:
Although it is not possible to estimate the long-term health risks associated with e-cigarettes precisely, the available data suggest that they are unlikely to exceed 5% of those associated with smoked tobacco products, and may well be substantially lower than this figure.
Answer: See above — this still anchors the claim at 5%. That “may well be” is a rather weaker statement than the “at least” (though it is, of course, a legitimate scientific statement, as opposed to “at least”). Indeed, it is an extremely weak and misleading way of saying “it would be extremely surprising if it were as high as 5%”, which is a valid claim. The implicit claim is still that 5% is the right point estimate. It goes without saying that in cases where we do not have a lot of really solid evidence, the true value may well be lower, even by a lot. But a point estimate also means that the true value may well be higher.
Now that the claims include more words than will fit on a bumper sticker, we can drill down a bit more to what is being claimed. The RCP authors, to their credit, note that there are minimal short-term health effects (which contrasts with smoking). So what risks are they actually claiming? There must be some scalar that the ratio claim applies to. In the above executive summary material they refer to “health risks”; in the body of the report they instead say “harm”. So are they saying that e-cigarettes cause 5% the risk of stroke, 5% the risk of lung cancer, 5% the risk of aortic rupture, etc.? Seems unlikely. When they add “harm” are they also claiming 5% of the accelerated tissue aging, etc.? Seems even less likely.
So it becomes apparent that even those touted as the “more scientific” contributors to the 5%-er madness are not actually making meaningful statements.
Question: But we need to be able to say something to counter the nonsense claims that all tobacco products are equally harmful and such.
Answer: Why not use the truth?
Question: The truth??
Answer: Ok, fair enough. Why not use the best evidence-based estimate of the real point estimate, for an actual well-defined scalar, like the chance it will kill the consumer (i.e., substantially hasten his death) or, roughly equivalently, the chance it will cause life-threatening disease.
Question: But you just said there is no such evidence for e-cigarettes.
Answer: No, I said we do not have epidemiology about long-term effects. That does not mean we do not have any evidence.
Question: Go on.
Answer: Thank you. As I have explained at length, repeatedly, for a decade now, the solid evidence we have about the long-term effects of nicotine consumption is based on ample evidence about smokeless tobacco. The evidence-based point estimate of the risk of it causing a consumer’s death was about 1% of that from smoking. In retrospect, that decade-old calculation seems a bit pessimistic, but it remains basically solid. E-cigarettes might cause a bit more risk — lung involvement and various novel exposures create that possibility. (There is no conceivable way e-cigarettes could be lower risk, controlling for dosage, because basically all of that point estimate is about the nicotine.) But the existing short-term evidence about vaping gives us confidence that a lot of possible effects are below the limits of detection and our knowledge of the chemistry and occupational epidemiology give us decent confidence that the long-term risks are pretty minimal.
In short, there is a very solid basis for a point estimate of 99% less harmful.
It kind of seems like win-win-win (for everyone other than the tobacco controllers, that is). There is a vanishingly small chance this figure is further from the truth than the 95% claim. It is actually based on evidence, rather than being a number someone pulled out of the air and others just repeated because tobacco control politics frowns upon bringing up points of scientific disagreement. Oh, and in case it is not obvious, 1% is less than 5%.
Question: But 1% is not much different from 5%.
Answer: Oh, but it is. It is enough different that it brings it down into the range of countless everyday hazards, rather than keeping it up in the list of top hazardous consumer choices. It is not all that difficult to justify(*) prohibitionist “regulation” of something that is 5% as harmful as smoking. If you drop to 1%, that would mean justifying heavy-handed regulation of almost every consumer choice.
(*This assumes, of course, that someone thinks it is ever ethically acceptable to use police powers and disinformation to manipulate people’s choices “for their own good”. I expect most readers of this blog, along with a mostly silent majority of everyone else, disagree. That is a far better argument, by the way, one that actually defends the hill you really want to defend: “I don’t care if it is 1%, 5%, or 50% as harmful as smoking. You have no right to tell me I cannot make that choice.” But that is a different dialogue.)
Oh, but you are right about one thing. “99% less” and “95% less” are close enough at a gut level that you are not going to lose anyone by claiming the figure that is better rather than the one that is wrong at every level. There is virtually no one out there who would accept “95%” upon hearing it, but who would be thinking “you know, if they had claimed 99% I would have said ‘no way, can’t be true, so must really be just as bad as smoking’ but since they said 95%, I will just accept that as true.” So the common protest, “the important thing is to move people away from believing the risk is the same as smoking!”, is not an argument for making the bad claim. The better claim does that equally as well.
Question: I was just about to bring up that “the important thing is…” point.
Answer: A good socratic dialogician always knows out all the likely comments before starting.
Question: But we still have to concede that it is harmful, right?
Answer: The actual scientific answer is that this is far from obvious. Recall that the 1% figure was based on the chance of the exposure causing substantially hastened death. It does not account for the other side of the ledger, causing a substantially delayed death (aka “preventing” a death). The net effect could well be zero or less (i.e., a net protective effect). Smoking and smokeless tobacco use protect against several nasty diseases. There is a good case to be made that smokeless tobacco is good for your health, on net. It is too close to be sure, given the limits of the science, but a net of zero is a pretty good point estimate. The case is a bit harder to make for e-cigarettes (some of the benefits might be from other chemicals; e-cigarettes have the additional possible risks), but hardly heroic. So it is far from clear that the net health effect of vaping is negative.
Question: But that is going to be much harder to sell to people than the “9x% less” claims.
Answer: Granted. Depending on your audience, you probably do not want to try to make that case (though you might want to keep it in your back pocket if they prove open to reason). People categorize exposures naively — “good”, “bad” — and so convincing them that it may well be good is a huge step. But they also homogenize small probabilities, such that 1/20, 1/100, and 1/10^12 are all about the same to them so, again, there is no reason to concede the 1/20.
Question: So what you are really saying is that we are being suckered into repeating a claim that is based on nothing, and that primarily serves the agenda of one clique of tobacco controllers? And while their agenda is somewhat more aligned with both science and the freedom I deserve than other tobacco controllers, it is still an agenda, and one that is ultimately a threat to science and the freedom I deserve? And that the truth is far better, in every way, including supporting my goals, than this claim? And while politically we may choose to ally with people who are not really on our side, it does not mean that we have to bite at every piece of tempting bait they dangle in front of us? Are you saying we can do better than this?
Answer: Yes. Thank you. It is as if you read my mind. Or perhaps you just read what I have actually written. In any case, you avoided surrendering to the common base urge of, “I heard this claim and uncritically accepted it, and I even repeated it, and now because I am subconsciously unwilling to ever accept that I was wrong in a belief, no matter how it was created, I am going to fight tooth-and-nail against anyone who points out it is wrong, baseless, and ultimately harmful to my cause.”
Question: Do you think your analysis and calling attention to this is going to make any difference?
Answer: Nope. I have long-since gotten used to my role as Cassandra.