Tobacco in Capsule
Tobacco smoking became a mass phenomenon only in modern times with addiction to cigarettes. A specific role of tobacco smoking was demonstrated clinically only for peripheral arterial disease until Cause of Death (COD) epidemiological studies arrived. The first major report on risk of COD and lung cancer by levels of cigarette smoking was the Richard Doll and Bradford Hill study of British physician panels in the early 1950s. It was followed by the massive study of smoking habits in the survey of Hammond and Horn in 1958.
Mechanisms of tobacco on physiology and metabolism include a wide variety of effects found in clinical and population studies: on sympathetic nervous activity, hemostasis, carboxyhemoglobin levels, and oxidative reactions, none sufficient, however, to explain the dose-related excess CVD morbidity and mortality experience of smokers.
Smoking cessation trials similarly have not provided clear data on tobacco risk; they are only suggestive of independent tobacco effects. At any rate, observational studies remain the major source of evidence for health policy on tobacco. The strong dose-relation association of cigarette smoking and CVD rates has been sufficient evidence, nevertheless, for all but a few investigators to recommend smoking cessation, prevention programs, and national smoke-free policy, absent experimental “proof.”
The national debate on smoking has resulted collaterally in the formulation of improved criteria for causal inference from statistical data. It has produced innovative regulatory strategies for the public health, such as “Clean Air Acts” and smoke-free institutions. The evidence allowed evolution of major legal settlements that established tobacco industry liability for excess mortality, based on deception in its goals to create youth addiction. Legislation has banned most tobacco advertising and encouraged no-smoking and cessation programs. It has failed to make illegal the tobacco industry or smoking in private, and seems not to have impaired the tobacco economy worldwide. (Henry Blackburn)
 Hammond, E.C., Horn, D. 1958. Smoking in Relation to Death Rates. Journal of the American Medical Association 166: 1159-1172.