tobacco and its effect on health

History[edit]
Concern about health effects of tobacco has a long history. Gideon Lincecum, an American naturalist and practitioner of botanical medicine, wrote in the early 19th century on tobacco: "This poisonous plant has been used a great deal as a medicine by the old school faculty, and thousands have been slain by it. ... It is a very dangerous article, and use it as you will, it always diminishes the vital energies in exact proportion to the quantity used - it may be slowly, but it is very sure."[15]
The late-19th century invention of automated cigarette-making machinery in the American South made possible mass production of cigarettes at low cost, and cigarettes became elegant and fashionable among society men as the Victorian era gave way to the Edwardian. In 1912, American Dr. Isaac Adler was the first to strongly suggest that lung cancer is related to smoking.[16] In 1924, economist Irving Fisher wrote an anti-smoking article for the Readers Digest, which said "... tobacco lowers the whole tone of the body and decreases its vital power and resistance ... tobacco acts like a narcotic poison, like opium and like alcohol, though usually in a less degree".[17] In 1929, Fritz Lickint of Dresden,Germany, published a formal statistical evidence of a lung cancer-tobacco link, based on a study showing that lung cancer sufferers were likely to be smokers.[18] Lickint also argued that tobacco use was the best way to explain the fact that lung cancer struck men four or five times more often than women (since women smoked much less).[18]
Prior to World War I, lung cancer was considered to be a rare disease, which most physicians would never see during their career.[19][20] With the postwar rise in popularity of cigarette smoking, however, came an epidemic of lung cancer.
In 1950, Richard Doll published research in the British Medical Journal showing a close link between smoking and lung cancer.[21] Four years later, in 1954, the British Doctors Study, a study of some 40,000 doctors over 20 years, confirmed the suggestion, based on which the government issued advice that smoking and lung cancer rates were related.[22] The British Doctors Study lasted until 2001, with results published every ten years and final results published in 2004 by Doll and Richard Peto.[23] Much early research was also done by Alton Ochsner. Reader's Digest magazine for many years published frequent anti-smoking articles. On January 11, 1964, the United States Surgeon General'sReport on Smoking and Health was published; this led millions of American smokers to quit, the banning of certain advertising, and the requirement of warning labels on tobacco products.
Studies[edit]
The term "smoker" is used to mean a person who habitually smokes tobacco on a daily basis. This category has been the focus of the vast majority of tobacco studies. However, the health effects of less-than-daily smoking are far less well understood. Studies have often taken the data of "occasional smokers" (those who have never smoked daily) and grouped them with those who have never smoked.[24]
In the 1930s German scientists showed that cigarette smoking caused lung cancer.[25]:15 In 1938 a study by a Johns Hopkins University scientist suggested a strongly negative correlation between smoking and lifespan. In 1950 five studies were published in which "smoking was powerfully implicated in the causation of lung cancer".[26] These included the now classic paper "Smoking and Carcinoma of the Lung" which appeared in the British Medical Journal. This paper reported that "heavy smokers were fifty times as likely as non-smokers to contract lung cancer".[21][26]
In 1953, scientists at the Sloan-Kettering Institute in New York City demonstrated that cigarette tar painted on the skin of mice caused fatal cancers.[25] This work attracted much media attention; the New York Times and Life both covered the issue. The Reader's Digest published an article entitled "Cancer by the Carton".[25]:14
A team of British scientists headed by Richard Doll carried out a longitudinal study of 34,439 medical specialists from 1951 to 2001, generally called the "British Doctors Study."[23]The study demonstrated that about half of the persistent cigarette smokers born in 1900–1909 were eventually killed by their addiction (calculated from the logarithms of the probabilities of surviving from 35–70, 70–80, and 80–90) and about two thirds of the persistent cigarette smokers born in the 1920s would eventually be killed by their addiction.
The health effects of tobacco have been significant for the development of the science of epidemiology. As the mechanism of carcinogenicity is radiomimetic or radiological, the effects are stochastic. Definite statements can be made only on the relative increased or decreased probabilities of contracting a given disease; For a particular individual, it is impossible to definitively prove a direct causal link between exposure to a radiomimetic poison such as tobacco smoke and the cancer that follows; such statements can only be made at the aggregate population level. Tobacco companies have capitalized on this philosophical objection and exploited the doubts of clinicians, who consider only individual cases, on the causal link in the stochastic expression of the toxicity as actual disease.[27]
There have been multiple court cases on the issue that tobacco companies have researched the health effects of tobacco, but suppressed the findings or formatted them to imply lessened or no hazard.[27]
A 2006 European study on occasional smoking published findings that the risk of the major smoking-related cancers for occasional smokers was 1.24 times that of those who have never smoked at all but the result was not statistically significant. (For a confidence interval of 95%, this data showed an incidence rate ratio of 0.80 to 1.94.)[24] (Data reduction used Cox proportional hazard model, stratified by gender and country.) This compares to studies showing that habitual heavy smokers have greater than 50 times the incidence of smoking-related cancers. After a ban on smoking in all enclosed public places was introduced in Scotland in March 2006, there was a 17 percent reduction in hospital admissions for acute coronary syndrome. 67% of the decrease occurred in non-smokers.[28]
A study published in the journal Pediatrics refers to the danger posed by what the authors call "third-hand smoke" — toxic substances that remain in areas where smoking has recently occurred.[29]
Overview and prevalence[edit]

Percentage of females smoking any tobacco product

Percentage of males smoking any tobacco product. Note that there is a difference between the scales used for females and the scales used for males.[3]
Tobacco may be consumed by either smoking or other smokeless methods such as chewing, the World Health Organization (WHO) only collects data on smoked tobacco.[1] Smoking has therefore been studied more extensively than any other form of consumption.[2]
In 2000, smoking was practiced by 1.22 billion people, predicted to rise to 1.45 billion people in 2010 and 1.5 to 1.9 billion by 2025. If prevalence had decreased by 2% a year since 2000 this figure would have been 1.3 billion in 2010 and 2025.[30] Despite dropping by 0.4 percent from 2009 to 2010, the United States still reports an average of 17.9 percent usage.[31]
As of 2002, about twenty percent of young teens (13–15) smoke worldwide, with 80,000 to 100,000 children taking up the addiction every day—roughly half of whom live in Asia. Half of those who begin smoking in adolescent years are projected to go on to smoke for 15 to 20 years.[32]
The WHO states that "Much of the disease burden and premature mortality attributable to tobacco use disproportionately affect the poor". Of the 1.22 billion smokers, 1 billion of them live in developing or transitional nations. Rates of smoking have leveled off or declined in the developed world.[33] In the developing world, however, tobacco consumption is rising by 3.4% per year as of 2002.[32]
The WHO in 2004 projected 58.8 million deaths to occur globally,[34]:8 from which 5.4 million are tobacco-attributed,[34]:23 and 4.9 million as of 2007.[35] As of 2002, 70% of the deaths are in developing countries.[35]
The shift in prevalence of tobacco smoking to a younger demographic, mainly in the developing world, can be attributed to several factors. The tobacco industry spends up to $12.5 billion annually on advertising, which is increasingly geared towards adolescents in the developing world because they are a very vulnerable audience for the marketing campaigns. Adolescents have more difficulty understanding the long term health risks that are associated with smoking and are also more easily influenced by “images of romance, success, sophistication, popularity, and adventure which advertising suggests they could achieve through the consumption of cigarettes”. This shift in marketing towards adolescents and even children in the tobacco industry is debilitating to organizations’ and countries’ efforts to improve child health and mortality in the developing world. It reverses or halts the effects of the work that has been done to improve health care in these countries, and although smoking is deemed as a “voluntary” health risk, the marketing of tobacco towards very impressionable adolescents in the developing world makes it less of a voluntary action and more of an inevitable shift.[5]
Many government regulations have been passed to protect citizens from harm caused by public environmental tobacco smoke. The "Pro-Children Act of 2001" prohibits smoking within any facility that provides health care, day care, library services, or elementary and secondary education to children.[36] On May 23, 2011, New York City enforced a smoking ban for all parks, beaches, and pedestrian malls in an attempt to eliminate threats posed to civilians by environmental tobacco smoke.[37]