RENEE MONTAGNE, HOST:
And we know that smoking causes a host of deadly diseases. The U.S. surgeon general lists 21. Now a study in the New England Journal of Medicine points to more than a dozen diseases not on that list - diseases that apparently add to tobacco's death toll. Here's NPR's Richard Harris.
RICHARD HARRIS, BYLINE: There's no question smoking increases the risk of lung cancer, heart disease, chronic obstructive pulmonary disease, esophageal cancer, mouth cancer and a long list of other diseases.
ERIC JACOBS: But in fact, we suspect that smoking may cause more diseases than just those on the list.
HARRIS: So Eric Jacobs at the American Cancer Society led a 10-year study to track nearly a million smokers and non-smokers and to tally up their causes of death. The scientists found that 17 percent of the excess deaths among smokers were not caused by the diseases on the surgeon general's list.
JACOBS: Things like kidney failure, infections and certain types of heart and respiratory diseases that weren't previously counted.
HARRIS: For five of the diseases on this new list, smokers were about twice as likely to die from these ailments as non-smokers.
JACOBS: So it's not a trivial increase in risk.
HARRIS: Jacobs says there are plausible reasons since to link smoking to these diseases. Smoking can suppress the immune system, which could explain why there are higher rates of death by infection among smokers. And the link to kidney disease makes sense, too.
JACOBS: Smoking is now established as a cause of diabetes, which is one of the huge causes of kidney failure in this country.
HARRIS: And up these potential smoking-related diseases, and tobacco kills an additional 60,000 Americans a year, on top of the more than 430,000 deaths caused by diseases on the surgeon general's list. These additional cancers alone represent almost twice the number of people who die in traffic accidents.
JACOBS: We've known for a long time that smoking kills. We do think, though, it's important to get an accurate estimate of just how many people are killed.
HARRIS: Overall, tobacco causes 1 in 5 deaths in the United States or, as this study suggests, maybe even a little bit more. Richard Harris, NPR News.
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