Go Tobacco - the main threat | Smoking and health
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Tobacco: a review of its effects on health

  • Evidence of causation
  • Quantitative assessment of the effects of smoking
  • Relationships reflecting the combined effects of smoking and other factors.
  • Interrelations reflecting the protective effect of tobacco
  • Forced or passive smoking
  • Conclusion
  • The effect of the dose and duration of smoking on the incidence of lung cancer
  • When tobacco was first imported into Europe at the end of the sixteenth century, smoking was recommended for medicinal purposes; but the expediency of using tobacco soon became controversial, and it was condemned as a pernicious evil as often as it was praised for its preventive value. However, until the second half of the 1940s, little scientific evidence was obtained regarding the effects of smoking. During this period, medical textbooks either completely ignored this question or briefly mentioned the harmful effects of this habit; tobacco amblyopia - a form of blindness associated with excessive smoking of tobacco and poor nutrition; tobacco angina - a rare form of angina in which chest pain occurs suddenly during smoking; cancer of the lips and tongue, which experienced surgeons have long considered associated with smoking a pipe. Then in 1950, five papers were published in Great Britain and the United States that compared the prevalence of smoking among a large number of patients with lung cancer (or in some studies with cancer of the oral cavity, pharynx, or larynx) and among those in the control group. In one of these works, it was concluded that “smoking is one of the reasons and an important factor in the onset and development of lung cancer,” and this was the beginning of the modern era in studying the effects of smoking on people's health.

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    The results of these studies are shown in Table 1, along with the findings of three smaller and less detailed studies published in Germany and the Netherlands over the previous 11 years. In six of these works there was an opportunity to make a comparison between heavy smokers and non-smokers. The findings suggest that smokers may be 3–30 times more likely to develop lung cancer than non-smokers; such differences were partly due to the peculiarities of smoking habits in different countries, but more important was the inconsistency in the approaches to defining the category of “non-smokers”, in which at least one study also included smokers.

    Obviously, to verify the findings of these works, it would be necessary to record the smoking habits of a large number of men and women with different smoking regimens, to provide follow-up monitoring of the state of health of these individuals for a long time and try as a result to determine whether it is possible; use the identified features as a predictor of lung cancer risk. Moreover, it turned out that with this method it is possible to study the relationship not only between smoking and lung cancer, but also between smoking and all other diseases reported in a significant number of cases during the observation period.

    Many studies of this kind have already been carried out, and in eight of them a sufficiently large number of individuals have been covered for quite a long time, which provides useful information on a wide range of diseases. All of them were limited to the study of mortality rates, and all give qualitatively similar results, despite the fact that four of them were performed in the United States, and one each in Canada, the United Kingdom, Japan and Sweden. All of them equally showed that smoking cigarettes is generally associated with higher mortality rates than smoking pipes and cigars, and most of these studies showed that the use of pipes and cigars is only weakly associated with the development of any other diseases besides cancer. upper respiratory tract and digestive tract (lips, tongue, oral cavity, pharynx, with the exception of the nasal part, and esophagus) *. In this regard, the rest of this chapter will be mainly limited to considering the effects of cigarette smoking, which is now undoubtedly the main mode of tobacco use worldwide, with the exception of some regions of Asia and Africa, where they continue to use tobacco products made in the form of special local forms, more like small cigars. When using these types of tobacco products, very large amounts of nicotine and tar are released, and therefore in such cases the effects on the health of people of each of these components should be studied separately.

    All these studies show large differences in the risk of death (on the order of 10-fold to 40-fold) between men who smoked 20 or more cigarettes a day and never smoked in their lives, from lung cancer, some other types of cancer of the upper divisions. respiratory tract and upper digestive tract, chronic bronchitis and emphysema (now it is preferable to call chronic obstructive pulmonary disease), right ventricular failure and aortic aneurysm; less pronounced differences are observed with respect to the risk of death from some other cancers and a wide range of other diseases, ranging from coronary heart disease, including pulmonary tuberculosis and peptic ulcers of the stomach , to liver cirrhosis and suicides. However, for many of these diseases, it is not easy to decide how much these differences in mortality rates reflect the role of cigarette smoking in the development of these diseases, and how much they are due to mixed influence, that is, the relationship between smoking and other aspects of a person’s lifestyle or his personality, which were the direct cause of the development of this state.

    * An exception is the Swedish study, which reveals that the relative risk of developing lung cancer is equally high in both pipe smokers and cigarette smokers.