Yesterday The New York Times marked World No Tobacco Day with a front-page story that illustrates the pervasive evasiveness of the anti-smoking movement regarding the relative hazards posed by different forms of tobacco consumption. The article, about burgeoning bans on hookah bars, admits that the main goal of this policy is not to protect bystanders from secondhand smoke but to protect patrons of these establishments from their own unhealthy habits. Given this context, readers naturally will want to know how the hazards of hookahs compare to the hazards of cigarettes. Yet the Times deliberately dodges this question. Here is how the story opens:

Kevin Shapiro, a 20-year-old math and physics major at the University of Pennsylvania, first tried a hookah at a campus party. He liked the exotic water pipe so much that he chipped in to buy one for his fraternity house, where he says it makes a useful social lubricant at parties. Like many other students who are embracing hookahs on campuses nationwide, Mr. Shapiro believes that hookah smoke is less dangerous than cigarette smoke because it "is filtered through water, so you get fewer solid particles." "Considering I don't do it that often, once a month if that, I'm not really concerned with the health effects," he added. But in fact, hookahs are far from safe.

Despite the implication, there is no contradiction between the belief that "hookah smoke is less dangerous than cigarette smoke," or the belief that occasional hookah smoking does not pose a health risk that is worth worrying about, and the statement that "hookahs are far from safe." Later the Times further muddies the hookah water:

Researchers say the notion that water filters all the harmful chemicals in tobacco smoke is a myth. So, too, they say, is the idea that because hookah smoking is an occasional activity, users are inhaling much less smoke than cigarette users. Many young adults are misled by the sweet, aromatic and fruity quality of hookah smoke, which causes them to believe it is less harmful than hot, acrid cigarette smoke. In fact, because a typical hookah session can last up to an hour, with smokers typically taking long, deep breaths, the smoke inhaled can equal 100 cigarettes or more, according to a 2005 study by the World Health Organization. That study also found that the water in hookahs filters out less than 5 percent of the nicotine. Moreover, hookah smoke contains tar, heavy metals and other cancer-causing chemicals. An additional hazard: the tobacco in hookahs is heated with charcoal, leading to dangerously high levels of carbon monoxide, even for people who spend time in hookah bars without actually smoking, according to a recent University of Florida study. No surprise, then, that several studies have linked hookah use to many of the same diseases associated with cigarette smoking, like lung, oral and bladder cancer, as well as clogged arteries, heart disease and adverse effects during pregnancy.

When "researchers" deny "the notion that water filters all the harmful chemicals in tobacco smoke," they implicitly concede that it filters some of those chemicals. The Paris-based tobacco researcher Kamal Chaouachi, an expert on hookahs and a frequent critic of lazy propaganda equating them with cigarettes, cites research finding that hookah water can absorb 80 percent to 90 percent of the "tar" in unfiltered smoke.

In an interview with Chris Snowdon, Chaouachi cautions against facile comparisons between hookah and cigarette smoke, noting that the tobacco mixture in hookahs (which typically includes molasses and fruit) is heated to a much lower temperature:

The smoking mixture in a modern hookah (as it is used in Europe or the USA) is not burnt but heated to a great extent. This "detail" has tremendous chemical consequences because, in the end, the smoke is much less complex than that generated by a cigarette….Only a few hundred compounds vs. a few thousand were found in [the two] cases.

Chaouachi also warns that chemical analyses based on experiments with smoking machines (such as the one described here) can be misleading because machines do not smoke the same way humans do—a point that anti-smoking activists have been making for years regarding the "FTC method" for measuring cigarette yields. The chemical content of the smoke is obviously important to know in evaluating the health implications of the claim that the volume of smoke inhaled in one hookah session "can equal" the smoke inhaled from 100 cigarettes. If it were true that someone who smokes a hookah once a day (a very common pattern in some parts of the world) faces the same risks as a five-pack-a-day cigarette smoker (which seems to be the intended implication), wouldn't that association have shown up clearly in epidemiological research by now?

The same 2005 WHO report (PDF) that the Times cites to support the 100-cigarette claim puts a very different spin on the nicotine content of hookah smoke. While the Times says "the water in hookahs filters out less than 5 percent of the nicotine," implying that less nicotine is desirable, the WHO report suggests that reducing the nicotine content might increase health hazards, leading people to inhale more smoke for the same dose of the drug. The study Chaouachi mentions, however, indicates that water filtration absorbs a much larger percentage of "tar" than nicotine, which suggests a net reduction in risk.

While Chaouachi criticizes the WHO report for exaggerating what is known about the health hazards of hookah smoking, the wording of its conclusions suggests how skimpy the evidence is (emphasis added):

A waterpipe smoking session may expose the smoker to more smoke over a longer period of time than occurs when smoking a cigarette [or it may not]… Waterpipe smoking has not been studied as extensively as cigarette smoking; however, preliminary research on patterns of smoking, the chemistry of the smoke that is inhaled, and health effects supports the idea that waterpipe smoking is associated with many [but not all?] of the same risks [same magnitude or same type?] as cigarette smoking and may, in fact, involve some unique health risks [or may not]…. Using a waterpipe to smoke tobacco poses a serious potential health hazard to smokers… Using a waterpipe to smoke tobacco is not a safe alternative to cigarette smoking [but is it safer?]…. A typical [for whom?] 1-hour waterpipe smoking session involves inhaling 100-200 times the volume of smoke inhaled with a single cigarette [but how do the doses of toxins and carcinogens compare?]…. Even after it has passed through water, the smoke produced by a waterpipe contains high levels of toxic compounds [compared to what?]…. There is surprisingly little research addressing tobacco smoking using a waterpipe.

And so on. My point is not that hookah smoking is substantially safer than cigarette smoking (although it might be) or that Kevin Shapiro, the college student presented by the Times as a poster boy for ignorance of the subject, is right in thinking that the risk posed by an occasional hookah session is negligible (although he probably is). My point is that we don't know enough to make confident statements about the hazards of hookah smoking, beyond observing that inhaling smoke containing significant levels of toxins and carcinogens probably isn't good for your health. It should be OK for a newspaper reporter, a scientist, or a public health official to acknowledge this uncertainty, instead of reinforcing the mindless orthodoxy that insists all tobacco products are equally dangerous, no matter what the evidence shows.

In the case of smokeless tobacco and electronic cigarettes, this all-or-nothing approach does people a real disservice, dissuading smokers from adopting alternatives that would dramatically decrease their health risks and maybe save their lives. As a method of harm reduction, hookahs do not look nearly as promising. But in all of these cases, using misdirection and hyperbole to scare people away from politically incorrect choices is dishonest, insulting, and unethical.

More on hookah bans here.