Smoking: Unsafe at any dose, from the Harvard Men's Health Watch

Is smoking just a little bit, or only now and then, really a health problem? Yes, says the May issue of Harvard Men's Health Watch. Light and intermittent smoking are nearly as bad as heavy smoking.

The way doctors explain risk and smoking exposure may underplay the sizable risks of light smoking, giving some smokers false reassurance. Physicians traditionally quantify smoking in terms of "pack-years." In this system, smoking one pack of cigarettes a day for one year equals one pack-year. When doctors point out that the risks of smoking rise with increasing pack-years of exposure, patients may mistakenly assume that light smoking is minimally hazardous or even safe. A recent study shatters that illusion.

To evaluate the effects of light smoking, researchers from the University of California, San Francisco, reviewed over 800 published studies of smoking in adults ages 18 and older. They homed in on 45 studies that met their standards for scientific excellence and competence. Although the individual investigations used different criteria for light and intermittent ("social") smoking, each provided a careful evaluation of the health risks of low-dose cigarette exposure. All in all, light and intermittent smoking is nearly as dangerous as heavy smoking. The results are eye-opening, and, according to Harvard Men's Health Watch, should cause health care professionals to reconsider the pack-years model of explaining smoking risk.

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