Daily Beast national security correspondent Eli Lake gave up cigarettes in 2008, after years of suffering from smoking-related respiratory ailments, when his doctor warned him that he was heading for "a debilitating stroke." For two years Lake struggled against the urge to start smoking again, until he discovered that electronic cigarettes, which deliver nicotine in a propylene glycol vapor, were a much closer substitute for the habit than nicotine gum yet posed none of the health risks associated with inhaling combustion products. A harm reduction success story, right? Lake doesn't seem to think so. Even though the health risks posed by e-cigarettes are dramatically lower than the health risks posed by the conventional variety, he worries in a recent column, they still may be greater than zero:

After years of telling myself I'd found the perfect loophole, I thought it might be wise to check my facts. The consensus medical research today is that while electronic cigarettes are healthier than tobacco cigarettes, and a good way to end dependency on tobacco, they are not without health risks. Besides the nicotine, the other active ingredient in my cigarettes is propylene glycol, a substance the FDA classifies as GRAS, or "generally recognized as safe." But there's a catch. Most research about propylene glycol is about its effect when it's ingested as an additive in food. Less is known about the effects of inhaling it as a vapor—dozens and dozens of times a day. "The safety and efficacy of e-cigarettes have not been fully studied," says the FDA on its website, and consumers "have no way of knowing…how much nicotine or other potentially harmful chemicals are being inhaled during use."… Dr. Lowell Dale, the medical director of the Mayo Clinic's Tobacco Quitline, [told me] propylene glycol as a liquid…is "similar to antifreeze." "I think the potential is that they are harmful," Dale says. "I think there is less nicotine in those products, and they are not combustible, so you are not getting all the particulate matter you get from cigarettes." But, he adds, "we are just being very cautious about the long-term consequences of its use. It comes out of China. It's unregulated. There is a lot of evidence the products vary from cartridge to cartridge." Wonderful. Here I was thinking I was cheating death when I was more likely inhaling Chinese-made antifreeze.

Propylene glycol, which is not an "active ingredient" in e-cigarettes but a carrier in which the nicotine and flavoring are dissolved, is known as "nontoxic antifreeze." Guess why. As Lake notes, it is approved by the FDA as a safe food ingredient. It is also used in various FDA-approved medications, including cough syrup and nasal sprays. Calling it "antifreeze" is a scare tactic aimed at clouding the issue. While it's true that there is not much research on the effects of inhaling propylene glycol, a 2012 study found that, unlike tobacco smoke, e-cigarette vapor does not impair lung function in the short term.

E-cigarettes indisputably deliver nicotine without the myriad toxins and carcinogens generated by burning tobacco. Whatever long-term risk propylene glycol vapor may pose is bound to pale in comparison with the well-established hazards of inhaling all of the chemicals you get from cigarettes (which, by the way, include propylene glycol). The bottom line is that Lake is much better off, in terms of the health risks he faces, for having switched from Marlboro Lights to e-cigarettes. Public health officials and anti-smoking activists who obscure that point are endangering smokers' lives by discouraging them from switching to a much safer alternative.

Previous coverage of e-cigarettes here. For more on the "safety and efficacy" of e-cigarettes, see The Rest of the Story, the tobacco policy blog written by Boston University public health professor Michael Siegel.