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Smoking, inhalation and exhalation of the fumes of burning tobacco. Leaves of the tobacco plant are smoked in various ways. After a drying and curing process, they may be rolled into cigars or shredded for insertion into smoking pipes. Cigarettes, the most popular method of smoking, consist of finely shredded tobacco rolled in lightweight paper. About 46 million people in the United States smoke an estimated 420 billion cigarettes each year. Until the 1940s smoking was considered harmless, but laboratory and clinical research has since confirmed that tobacco smoke presents a hazard to health. Smoke from the average cigarette contains around 4,000 chemicals, some of which are highly toxic and at least 43 of which cause cancer. Nicotine, a major constituent of tobacco smoke, is both poisonous and highly addictive. According to the American Cancer Society, smoking is the most preventable cause of death in America today.
European explorers who arrived in the Western Hemisphere in the 1500s observed Native Americans smoking tobacco plant leaves in pipes. The colonists who followed them grew tobacco plants as a cash crop for export, and smoking became part of European culture by the 1600s. Most tobacco was consumed in pipes and cigars or as snuff (finely pulverized tobacco inhaled into the nostrils). This pattern changed by the early 20th century, by which time smokers consumed more than 1,000 cigarettes per capita each year in the United States and some European countries. The general attitude of society was that smoking relieved tension and produced no ill effects. During World War II (1939-1945) American physicians endorsed sending soldiers tobacco, and cigarettes were included in the field ration kits of U.S. armed forces personnel until 1975. Some scientists noticed, however, that lung cancer, which was rare before the 20th century, had increased dramatically since about 1930. The American Cancer Society and other organizations initiated studies comparing deaths among smokers and nonsmokers over a period of several years. All such studies found increased mortality among smokers, both from cancer and other causes. In addition, experimental studies in animals showed that many of the chemicals contained in cigarette smoke are carcinogenic. More from Encarta In 1962 the U.S. government appointed a panel of ten scientists to study the available evidence concerning the health effects of smoking. Their conclusions were included in the 1964 surgeon general’s report, which stated that “cigarette smoking is a health hazard of sufficient importance in the United States to warrant appropriate remedial action.” Smoking in adults, measured as an average number of cigarettes smoked per year, began to decline steadily after the 1964 report and has fallen more than 40 percent since 1965.
About 442,000 people in the United States die each year from illnesses caused by cigarette smoking. Smoking accounts for nearly 90 percent of lung cancer deaths. Additionally, smokers are at increased risk for cancer of the larynx, oral cavity, esophagus, bladder, kidney, and pancreas. While some negative health effects of smoking manifest slowly over time, others can be measured almost immediately. Sticky brown tar leaves yellow stains on fingers and teeth. Some of the inhaled tar is absorbed by lung cells, causing them to die. Tar also damages the cilia in the upper airways that protect against infection. Nicotine causes arteries to constrict, lowering skin temperature and reducing blood flow to the hands and feet. Carbon monoxide deprives the body of oxygen, binding to red blood cells in place of the oxygen molecule and forcing the heart to pump more blood through the body. One-third of smoking-related deaths are caused by coronary heart disease or chronic airway obstruction. For example, the nicotine in tobacco combines with carbon monoxide in tobacco smoke to damage the lining of blood vessels and make blood platelets stickier. Platelets form part of the damaging plaque buildup in artery walls (see Arteriosclerosis). These effects in combination contribute to the development of heart disease. Smoking also increases the risk of stroke by 50 percent—40 percent among men and 60 percent among women. Other research has shown that mothers who smoke give birth more frequently to premature or underweight babies, probably because of a decrease in blood flow to the placenta. Babies born to mothers who smoke during pregnancy are also at increased risk for sudden infant death syndrome. Cigar and pipe smoke contains the same toxic and carcinogenic compounds found in cigarette smoke. A report by the National Cancer Institute concluded that the mortality rates from cancer of the mouth, throat, larynx, pharynx, and esophagus are approximately equal in users of cigarettes, cigars, and pipes. Rates of coronary heart disease, lung cancer, emphysema, and chronic bronchitis are elevated for cigar and pipe smokers and are correlated to the amount of smoking and the degree of inhalation. Studies have found that cigarettes are addictive because an unknown component of tobacco smoke appears to destroy an important brain enzyme known as monoamine oxidase B (MAO B). The enzyme is vital for breaking down excess amounts of dopamine, a neurotransmitter that triggers pleasure-seeking behavior. Smokers have decreased levels of MAO B and abnormally high levels of dopamine, which may encourage the smoker to seek the pleasure of more tobacco smoke. Even nonsmokers are at risk from smoking. Recent research has focused on the effects of environmental tobacco smoke (ETS)—that is, the effect of tobacco smoke on nonsmokers who must share the same environment with a smoker. The United States Environmental Protection Agency (EPA) estimates that exposure to ETS, which contains all the toxic agents inhaled by a smoker, causes 3,000 lung cancer deaths and an estimated 35,000 deaths from heart disease per year among nonsmokers. Secondhand smoke can aggravate asthma, pneumonia, and bronchitis, and impair blood circulation. The smoking habit and addiction to nicotine usually begin at an early age. In the United States, more than 90 percent of adults who smoke started by age 21, and nearly half of them were regular smokers by the age of 18. Despite increasing warnings about the health hazards of smoking and widespread bans on smoking in public places, smoking remains common among teenagers and young adults. In 2001 surveys of students in grades 9 through 12 found that more than 38 percent of male students and nearly 30 percent of female students smoke. Although black teenagers have the lowest smoking rates of any racial group, cigarette smoking among black teens increased 80 percent in the late 1990s. Advertisements aimed at a young audience are largely blamed for this new generation of smokers.
Studies of former smokers show that their risk of dying from smoking-related disease decreases with each year of abstinence. According to the World Health Organization (WHO), smokers who quit smoking before the age of 50 reduce their risk of life-threatening disease by half after just one year, compared with those who continue smoking. Other benefits of quitting smoking include more disposable income, admission to social activities and institutions that ban smoking, and often, lower health insurance premiums. Nonetheless, to quit smoking is difficult, most likely because smokers crave the effect of the nicotine in the smoke. The U.S. surgeon general declared nicotine an addictive drug comparable to other addictive substances, including cocaine, heroin, and alcohol, in its ability to induce dependence. Overall, tobacco smoking causes about 20 times the number of deaths in the United States than all other addictive drugs combined. Smoking cessation methods are plentiful, and many books and products are available to help an individual stop smoking. Many smokers turn to group help because of the support and understanding provided by other former smokers or people trying to quit. Most successful group-help techniques involve a challenge and reward system that also bolsters the self-discipline of the former smoker. One study found that smokers are more likely to quit within social networks. These networks are not necessarily organized support groups; they may consist of friends or co-workers. A number of nicotine replacement products are available to help a person quit smoking. Nicotine patches are small, nicotine-containing adhesive disks that must be applied to the skin. The nicotine is slowly absorbed through the skin and enters the bloodstream. Over time, a smoker uses nicotine patches containing smaller and smaller doses of nicotine until eventually the craving for nicotine ends. Nicotine gum works in a similar manner, providing small doses of nicotine when chewed. A nicotine nasal spray is a physician-prescribed spray that relieves cravings for a cigarette by delivering nicotine to the nasal membranes. Also available by prescription, the nicotine inhaler looks like a cigarette; when puffed, the inhaler releases nicotine into the mouth. An approach combining three different smoking cessation therapies has found remarkable success. This approach combines an antidepressant drug called bupropin, marketed under the brand name Zyban, with a nicotine replacement product and counseling. While less than 25 percent of smokers who use nicotine replacement products alone remain smoke-free for more than a year, 40 to 60 percent of smokers using this combination approach achieved this milestone.
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