Mothers who smoke cigarettes may damage their children's lungs and cause lung disease later, Harvard doctors reported yesterday.
The report is the latest of several studies that mostly show growing concern with the potential health effects of "passive" or "involuntary smoking"--that is, inhaling the smoke of others' cigarettes.
Physicians and statisticians at Harvard Medical School and two Harvard-affiliated Boston hospitals--Brigham and Women's and Beth Israel--make the latest report in today's New England Journal of Medicine.
The Harvard group first examined 1,156 Boston children aged 5 to 9 in 1974.
They reexamined them, and often interviewed their parents and other family members, every year for six years.
They regularly measured the children's "forced expiratory volume" and "forced expiratory flow"--in simpler terms, the youngsters' lung power or capacity as they grew older.
The lungs of those children whose mothers smoked showed 7 percent less increase in capacity, on average, than those whose mothers did not smoke.
The fathers' smoking had no such effect, perhaps because mothers spend more time with their children, especially in their first two years, when the effect may be greatest.
It is also possible, said the Harvard authors, that the effect on the lungs is indirect, caused by an observed increase in acute respiratory disease--colds, flu and the like--in children of smoking mothers.
The doctors call the loss in lung power "consistent with that hypothesized . . . to be an underlying risk predictor for obstructive airway disease"--emphysema or other lung problems--in adult life.
"We don't know yet" whether there will be an ill effect in adulthood, said Dr. Ira Tager of Brigham and Women's Hospital, the report's senior author. "My guess is that we are measuring something that has potential health implications" in those who become exposed to some added environmental danger, either by taking up smoking or by being exposed to some harmful chemical on the job.
What would he advise parents now?
"Obviously you'd like them not to smoke," he said, but if they must, they "should minimize or eliminate smoking around their young children to the extent that it's possible."
The Harvard article summed up the results of other studies of the effects of parental smoking. The results disagree--some show no effect on children's lungs--but the trend, Tager said, is to show an adverse effect.
In a half-page advertisement in yesterday's Washington Post and in several magazines, the Tobacco Institute said "no claim of adverse effect of cigarette smoke on a healthy nonsmoker has yet been proved," and "even the U.S. surgeon general, an outspoken critic of smoking, said in 1982 that the available evidence is not sufficient to conclude that other people's smoke causes disease in nonsmokers."
Surgeon General C. Everett Koop was discussing three studies indicating that breathing others' smoke may increase the risk of lung cancer. And he added in the same sentence that "the evidence does raise concern about a possible serious public health problem."