Health effects of tobacco smoking

Tobacco use, fueled by widespread addiction to nicotine, is the root cause of the 20th century epidemic of lung cancer, emphysema and numerous other fatal illnesses and chronic health problems. The average decrease of lifespan for a person smoking 20 cigarettes a day is about five years. The ill effects of smoking become manifest only after a period of years and may thus not appear to be obviously linked with the habit. Smoking is a major etiological factor in a number of disabling and fatal diseases, notably ischaemic heart disease, lung cancer, chronic bronchitis and emphysema. The mortality of cigarette smokers from many other diseases is greater than that of non-smokers, particularly in the case of peptic ulcer, and of cancers of the larynx, oral cavity, oesophagus and bladder. Smoking decreases the availability of vitamin C, essential for calcium uptake, which accounts for higher incidence of osteoporosis in smokers.

There is evidence of adverse effects of smoking by pregnant women on the foetus and the new born baby, and of increased risk of ill-health for very young children in smoking families. The synergistic effect of cigarette smoking and exposure to toxic industrial agents is well documented. Literature has also appeared on the effects of involuntary or 'passive' smoking (inhalation by non-smokers of sidestream smoke from the lighted tip of a cigarette between puffs as well as of exhaled mainstream smoke).

In 1990, it was estimated that tobacco-caused diseases would kill nearly 10% of the current world population, namely 500 million, unless present smoking patterns change. By 2030, 10 million people may die each year from smoking. About 250 million of the predicted victims would die in middle age (from 35 to 69), losing approximately 20 years of life. Of the current population under 20 years of age, about 800 million are expected to become smokers.

According to a 1999 report, 30% of deaths from cancer in the European Union can be traced to smoking. In Britain alone it is said to be responsible for 100,000 deaths per year. Among British physicians 35 years of age and older, studied over a long period of time, more than twice as many smokers as non-smokers died before reaching age 65. In France it has been calculated that as many as 60,000 deaths a year - including 18,500 cancer deaths, or 15% of all cancer deaths - are related to smoking. Since France has approximately 500,000 deaths per year, this means that 11 to 12% of all deaths are linked to smoking. A 1992, EC-wide study from the Cancer Research Campaign identified smoking as the biggest single cause of cancer, accounting for 30% of all cancer and almost all lung cancer. Although smoking among men, especially over the age of 55, is declining in the EEC/EU, it is increasing among women, especially between the ages of 15 and 24.

A 1993 report estimated 26% of Americans smoke, a great decline from 42% in 1965, the year following the surgeon general's first warning of the dangers of smoking. American cigarette consumption has been declining by an estimated 2 to 3% each year. For 1984, the USA Surgeon General officially attributed 350,000 deaths to smoking. A study of adults in a specific community in the USA, published in 1990, indicated that men who smoke cigarettes throughout their lives die nearly 18 years earlier than men who never start. Thus a 30-year old man who smokes will reduce his life expectancy, on average, by about one fourth -- dying at the age of 64 rather than 82. On the basis of an exhaustive review of worldwide scientific evidence, a USA report reached the conclusion that overall mortality for all cigarette smokers is about 70% higher than for non-smokers. Life expectancy for a 30-year old, two pack-a-day smoker is eight years less than for a non-smoker of the same age. Mortality rates are higher among those who have smoked for longer periods, those who started smoking at a younger age, and those who smoke cigarettes with a higher tar and nicotine content. Ex-smokers, however, experience a decline in mortality rates.

In a study of 902 heart attack patients, the researchers found that those who smoked a cigarette within six hours of developing symptoms had bigger blood clots in their arteries than those who had not smoked for a longer period of time. In general, the blood clot, or thrombus, that leads to a heart attack was larger in smokers than in non-smokers. Larger clots increase both the risk and severity of heart attacks as it is more likely to block blood flow to the heart completely. The less blood that gets to the heart, the more severe the damage.