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Secondhand Smoke: Nuisance or Menace?
June 03 2003
Maia Szalavitz
Exaggerating the risks of secondhand smoke

Secondhand smoke is smelly, the nasty odor lingers on your clothes and hair and it undoubtedly aggravates asthma, allergies and other respiratory conditions. But can it really increase your risk of death from heart disease and lung cancer - or have these fears been overblown?

A recent study published in the British Medical Journal followed over 35,000 non-smoking spouses of smokers from 1959 -1998. The authors found no significant increase in risk of death.

The study has been criticized by the American Cancer Society, which originally funded it, for not recognizing that in early parts of the research period, most people were widely exposed to secondhand smoke. This could obscure differences in risk between those heavily exposed and those presumed to be less exposed. The ACS and other health groups also criticized the authors for taking tobacco company money to complete the research.

Secondhand smoke research has always been difficult to interpret because it is so hard to measure actual exposure and find comparison groups that differ only in exposure levels. This is why the majority of secondhand smoke studies find little or no effect, and it is only when the data is pooled for meta-analysis are results seen.

Furthermore, if secondhand smoke was as dangerous as smoking itself or even close in risk level, the link between smoking and health problems could never have been uncovered when it was, because at that time so much of the population was so heavily exposed to secondhand smoke that comparisons wouldn't show much difference.

Anti-tobacco groups claim that passive smoke exposure increases cancer risk by 20 percent and heart disease risk by 30 percent. While that sounds like a large increase, most epidemiologists don't consider risk factors particularly worrisome until they get to about 200 percent.

Smoking a pack of cigarettes a day increases risk for all cancers by 200 percent, lung cancer by 1000 percent and heart disease 300-400 percent. Smoking two or more packs a day increases lung cancer risk by a factor of 15-25 (i.e., by 1500 percent to 2500 percent). In looking at research on any substance, it's important to keep in mind that dosage counts.

Oddly, though the smoking ban in bars in New York is based on the idea that passive smoke exposure is risky to employees, the new study wasn't covered by the anti-ban New York Post, nor by the Daily News or New York Times. Only Newsday ran an item covering the controversy. Reason critiqued the research and the UK's Daily Telegraph lambasted it in  two  opinion pieces and an editorial.

Smoking has become such an emotionally charged issue that the data itself gets lost in the clouds. For adults, secondhand smoke is probably more of a nuisance than a health menace. The media should not bow to health hysteria on one side or commercial pressures on the other and should put the data in context of other risks for their audience.
related links:

The American Council on Science and Health (an organization which often debunks health scares) has a pamphlet on secondhand smoke.



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