Disorders induced by tobacco smoking
Smoking is the main cause of many respiratory diseases and is one of the most important risk factors for cardiovascular diseases, cancers of several organs and many other pathological conditions. Estimates suggest that overall, approximately one-third of all cancers are caused by tobacco use. Of these, lung cancer is the prime example: in most societies, 80–90% of all lung cancers are attributable to tobacco. Lung cancer kills more people in the EU than any other cancer, accounting for about 20% of all cancer deaths. Tobacco smoking also plays a causal role in cancers of the mouth, larynx, pharynx, nose and sinuses, oesophagus, stomach, liver, pancreas, kidney, bladder, cervix and bowel, as well as one type of ovarian cancer and some types of leukaemia. Smoking is the main cause of COPD, particularly in Europe. (In some other parts of the world exposure to biomass fuels is relatively more important.) Smoking reduces the rate of growth of respiratory function during adolescence, resulting in a lower maximum forced expiratory volume in 1 s (FEV1) (a key measure of lung function) at maturity. Smoking then accelerates the decline of FEV1 in later adulthood and in old age. Figure 2 shows schematically the effect of smoking on FEV1 in healthy nonsmokers and susceptible smokers, as well as the effect of quitting smoking.
|Non-cancer effects||Smoke constituent||NCRI|
|Cardiovascular effects||Hydrogen cyanide||1.97|
Table 1 – Non-cancer risk indices (NCRI) for individual chemical constituents of mainstream cigarette smoke based on a single cigarette per day. Reference exposure levels (REL) are a guide to protect sensitive individuals against chronic effects over a long period of continuous exposure. The NCRI is equal to reported concentration as a fraction of the REL, assuming a total volume of 20 m3 of air breathed daily. Bold numbers indicate an NCRI greater than 1.0, which signals that the threshold for adverse effects could be reached for some people by smoking a single cigarette per day. Reproduced from Fowles et al., 2003, with permission from the publisher.
Smoking is also a cause of childhood asthma and a risk factor for the development of asthma in adults and is associated with increased risk of mortality, asthma attacks and exacerbations, greater severity and more difficulty in controlling asthma. Smoking predisposes to infection and is a serious complicating factor for tuberculosis.
Beyond the respiratory system, cigarette smoking is a risk factor for osteoporosis, reproductive disorders, adverse post- operative events and delayed wound healing, duodenal and gastric ulcers, periodontal disease and diabetes. It is a major modifiable risk factor for cardiovascular disease, including coronary artery disease, stroke, peripheral vascular disease and congestive heart failure. Studies of the relationship between cigarette smoking and cardiovascular disease show that cigarette smoking is associated with higher serum levels of cholesterol, coronary vasomotor reactivity, platelet aggregation and a pro-thrombotic state.