In the most comprehensive report of its kind to date, researchers have detailed the exact mechanisms by which secondhand smoke can damage the heart and circulatory system.
The report in today’s Journal of the American Medical Association presents new research by the University of California, San Francisco, and an analysis of the most recent scientific studies on secondhand smoke. It describes numerous pathways by which the components of tobacco smoke can lead to heart disease. Moreover, the researchers argue convincingly that even a small quantity of secondhand smoke causes adverse cardiovascular effects in nonsmokers.
The cardiovascular analysis is significant because most government regulations on secondhand smoke have been based on evidence that it can cause cancer; the Environmental Protection Agency has deemed it a Class A carcinogen. But the evidence regarding the effects of a small amount of secondhand smoke on heart disease has been controversial.
“We not only know that secondhand smoke causes heart disease, but we are now getting a very good idea of how it causes heart disease,” said the paper’s co-author, Stanton A. Glantz, of UC San Francisco.
In a statement issued Tuesday, tobacco industry leaders said that Glantz and co-author William W. Parmley ignored some studies that show no association between secondhand smoke and heart disease and failed to acknowledge their own conclusion that the risk of dying of heart disease as a result of secondhand smoke is small.
Until recently, most of the evidence that passive smoke causes heart disease in non-smokers was based on epidemiological studies that merely showed an association between people routinely exposed to secondhand smoke and an increased risk of heart disease. The analysis published Wednesday comprises recent clinical, laboratory and epidemiological studies that demonstrate the underlying physiological and biochemical changes from ingestion of environmental tobacco smoke.