Tobacco: an overview of its impact on health

  • Proof of causation
  • Quantitative assessment of the impact of Smoking
  • The relationship, reflects the combined impact of Smoking and other factors
  • The relationship, reflects the protective effect of tobacco
  • Involuntary or passive Smoking
  • Conclusion
  • The effect of dose and duration of Smoking on the incidence of lung cancer
  • When tobacco was first brought to Europe in the late sixteenth century, Smoking was recommended for therapeutic purposes; but the feasibility of using tobacco soon began to cause disputes, and condemned as pernicious evil as often as praised for his preventive value. However, until the second half of the 1940-ies was received little scientific data on the effects of Smoking. In this period of medical textbooks or completely ignored this issue or briefly mentioned about the harmful consequences of this habit; tobacco amblyopia is a form of blindness associated with excessive tobacco Smoking and poor nutrition; tobacco angina is a rare form of angina, which is chest pain arise suddenly while Smoking; cancer of the lip and tongue, which experienced surgeons for a long time considered related to Smoking pipe. Then, in 1950, in the UK and the USA published five works by comparing the prevalence of Smoking among a large number of lung cancer patients (or in some studies of cancer of the mouth, throat or larynx) and among those from the control group. In one of these works was made the conclusion that "Smoking is one of the reasons, and an important factor in the emergence and development of lung cancer," and with this began the modern era study of the impact of Smoking on health.
    The results of these studies are listed in table. 1 together with the findings of three smaller, less detailed studies published in Germany and the Netherlands for the past 11 years. In six of these works was able to make a comparison between smokers and non-Smoking people. The obtained data suggest that the risk of lung cancer in smokers may be at 3-30 times higher than non-smokers; these differences were partially conditioned by the peculiarities of Smoking habits in different countries, but more important was the inconsistency in approaches to the definition of the category "non-Smoking", in which at least one study included individuals who quit Smoking.
    Obviously, to verify made in these works conclusions would need to check the habit of Smoking among a great number of men and women with different modes area, to ensure follow-up of the health status of these individuals for a long time and try the result to determine whether it is possible; to use the features as a prognostic risk factor for lung cancer. Moreover, it turned out that this method to study the relationship not only between Smoking and lung cancer, but also between Smoking and all other diseases registered in a significant number of cases throughout the period of observation.
    Many such studies already carried out, and in eight of them covers a considerable number of people for quite a long time, which allows to obtain useful information on a wide range of diseases. They are all limited to the study of mortality rates, and all give qualitatively similar results, despite the fact that four of them were executed in the USA and one in Canada, the UK, Japan and Sweden. All of them are equally have shown that cigarette Smoking in General is associated with higher mortality rates than Smoking pipes and cigars, and in most of these studies have shown that the use of pipes and cigars only in small degree connected with the development of any other diseases other than cancer of the upper respiratory tract and the digestive tract (lip, tongue, mouth, throat, except for the nose and oesophagus) *. In this regard, the remainder of this Chapter will mainly limited to addressing the impact of cigarette Smoking, which is currently, of course, is the main method 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 a small cigars. When using these types of tobacco products are distinguished by very large amounts of nicotine and tar, and therefore in such cases, you should examine the impact on health of each of these components separately.
    All these studies indicate large differences in the risk of death (of the order of 10-fold up to 40 times) between men who smoke 20 or more cigarettes a day, and had never smoked, from lung cancer, other cancers of the upper respiratory tract and upper gastrointestinal tract, chronic bronchitis and emphysema (now preferred to be called chronic obstructive pulmonary disease), right ventricular failure and aortic aneurysm; less pronounced differences in the risk of death from certain other types of cancer and a wide range of other diseases from coronary heart disease, including tuberculosis and peptic ulcers of the stomach, and ending with liver cirrhosis and suicides. However, for many of these diseases are not easy to decide how these differences in mortality rates reflect the role of cigarette Smoking in the development of these diseases, and how they caused a mixed impact, i.e. the link between Smoking and other aspects of a person's lifestyle or the peculiarities of his character, which was the direct cause of this condition development.

    * The exception is the Swedish study, which revealed that the relative risk of lung cancer is equally high as persons, Smoking a pipe and cigarette Smoking.