Findings from a large study confirm that passive smoking increases the likelihood of developing lung diseases. Of particular concern, exposure to secondhand tobacco smoke during childhood raised the risk of lung cancer in adulthood by more than threefold.

As reported online by the British Medical Journal, Dr. P. Vineis, from Imperial College London, and colleagues analyzed data from 303,000 subjects who participated in the European Prospective Investigation into Cancer (EPIC) study.

The analysis focused on 123,479 subjects who provided information about exposure to secondhand smoke. During more than 7 years of follow-up, 97 people were diagnosed with lung cancer, 20 were diagnosed with upper respiratory malignancies, and 14 died from chronic obstructive pulmonary disease, which includes emphysema and chronic bronchitis.

In the overall analysis, exposure to environmental tobacco smoke raised the risk of all respiratory diseases by 30% and lung cancer by 34%, the researchers report.

Moreover, the risks of secondhand smoke were greater for ex-smokers than for people who never smoked.

People who were exposed as children to secondhand smoke for several hours on a daily basis were 3.6-times more likely to develop lung cancer during adulthood than their unexposed counterparts.

“This large prospective study…confirms that environmental tobacco smoke is a risk factor for lung cancer and other respiratory disease, particularly in ex-smokers,” the investigators conclude.

SOURCE: British Medical Journal, online January 28, 2005.