During recent years the medical profession has displayed increasing interest in the problem of tobacco smoking and its influence on persons who are in good health as well as on patients afflicted with disease.1 Numerous laboratory studies have been conducted in which the effects of tobacco smoke on normal animals have been investigated.2 These investigations have been important but have cast little light on the problem as it affects human beings owing to the fact that great differences exist between conditions of normal animals ordinarily unexposed to tobacco smoke and the varying states of human beings, who as a species have been exposed to this agent for many generations.
Pearl's study of human longevity in relationship to the smoking of tobacco has been an important contribution to the subject.3 His study indicated that the expectation of life of nonsmokers exceeded that of smokers and that among smokers
ENGLISH JP, WILLIUS FA, BERKSON J. TOBACCO AND CORONARY DISEASE. JAMA. 1940;115(16):1327-1329. doi:10.1001/jama.1940.02810420013004