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PASSIVE SMOKING: THE DEBATE EXPLODES

(June 2003)

Inhaling the cigarette smoke of others can be very annoying. Second-hand smoke can also increase the frequency of bronchitis and other respiratory infections in children, and it activates asthma and bronchitis. There is no argument about those unpleasant and unhealthy consequences of passive smoking. It is the following other claims that create controversy:

- that passive smoking increases the risk of coronary heart disease and heart attacks by 25 percent.

- that passive smoking can increase the risk of lung cancer in non-smokers by several fold; but, lung cancer is infrequent in non-smokers so that translates to only a 17 to 22 percent increase in risk.

- that passive smoking causes 3,000 lung cancer cases a year (out of a total of about 170,000 cases each year in the United States). That figure was sort of picked out of the hat; it is not really based on any adequate data.

The supposed increased risk of heart attacks or lung cancer is actually quite small - in this type of study, an increase of 17 to 25 percent is not very much. At least partly on the basis of these alleged risks, public anti-smoking policy in restaurants and bars has been established with bombastic statements about how many lives would be saved by these new anti-smoking regulations relating to second-hand smoke.

There have always been well-respected doubters. In January 2002, we reviewed several interesting reports that questioned whether passive smoking really did cause any increase in heart attacks and lung cancer (see the Archives article on passive smoking under Smoking).

That is the setting for a report in May 2003 in the British Medical Journal by James Enstrom of the School of Public Health, University of California in Los Angeles and Geoffrey Kabat of the Department of Preventive Medicine, State University of New York at Stony Brook. Their study is titled “Environmental tobacco smoke and tobacco-related mortality in a prospective study of Californians 1960-98. They studied 35, 561 individuals who were never smokers, but had a smoking spouse. Their main (and controversial) finding was “exposure to environmental tobacco smoke was not significantly associated with the death rate for coronary heart disease (heart attacks), lung cancer, or chronic obstructive pulmonary disease in men or women”.

The response was ferocious.

The study was called “inadequate”, “flawed”, “inaccurate”, “unreliable”, “biased”. Commented one highly-respected epidemiologist, “we have one very flawed study that does not find an association. It flies in the face of so much evidence and so much scientific understanding that it just doesn’t contribute”.

The American Cancer Society had institutional apoplexy. One spokesperson even challenged the study because some of the funding came from tobacco companies.

What goes on here? James Enstrom is no crackpot; he is a highly-respected epidemiologist who has carried out many good studies, including studies on the long-term dangers of smoking.

In responding to the intemperate attacks, Enstrom said “maybe the feelings about this issue are so strong that no one cares what the evidence shows”.

Let’s be clear. There is nothing wrong with this study - it is thoughtfully and carefully conducted.

The bottom line is that, as of this writing (late May 2003), we still do not know whether passive (second-hand) smoke causes an increased frequency of coronary heart disease, heart attacks, or lung cancer.

Cigarette smoking causes plenty of problems for smokers. It causes some problems for non-smokers, especially children and those with asthma or bronchitis. And, it can be annoying to non-smokers or those sensitive to the smoke. BUT, it has not been shown persuasively to cause either lung cancer or heart attacks. Anti-smoking enthusiasts should stop using claims about heart attacks or lung cancer in their campaigns until such time, if ever, that we have persuasive supporting evidence.

Enstrom, J.E., Kabat, G.C. Environmental tobacco smoke and tobacco related mortality in a prospective study of Californians, 1960-98. British Medical Journal. Vol 326 (May 17) Pgs 1057-1066. 2003.