Cigarette Smoke

Cigarette Smoke

Components of cigarette smoke

Environmental tobacco smoke

The health consequences of tobacco use

Cardiovascular disease

Cancer

Lung disease

Other health problems

Nicotine—addiction or habit?

Genes and nicotine addiction

The effects of quitting

Methods of treatment

Offense is the best defense

Resources

The World Health Organization (WHO) has named tobacco one of the greatest public health threats of the twenty-first century. As of 2006, about five million people were dying yearly from causes directly related to tobacco use. About half of the 650 million people smoking regularly worldwide were forecast to eventually die from smoking-related causes. This death rate was expected by WHO to rise to 10 million annually by the year 2020. Seventy percent of these deaths will occur in developing countries where the proportion of smokers is growing, particularly among women. Calling tobacco “a global threat,” WHO says these figures do not include the enormous physical, emotional, and economic costs associated with disease and disability caused by tobacco use.

In the United States alone, 25.2 million men, 23.2 million women, and 4.1 million teens between 12 and 17 years of age smoke. Every day, more than three million youths under the age of 18 begin smoking. The gruesome statistics show that more than five million children alive today will die prematurely because, as adolescents, they decided to use tobacco. Nationally, one in five of all deaths is related to tobacco use. It kills more than 430, 000 people every year—more than AIDS, alcohol, drug abuse, automobile accidents, murders, suicides, and fires combined. Five million years of potential life is lost every year due to premature death caused by tobacco use. Medical costs total more than $50 billion annually, and indirect cost another $50 billion.

Components of cigarette smoke

Of the 4, 000 or more different chemicals present in cigarette smoke, 60 are known to cause cancer and others to cause cellular genetic mutations that can lead to cancer. Cigarette smoke contains nicotine (a highly addictive chemical), tars, nitrosamines, and polycyclic hydrocarbons, all of which are carcinogenic. It also contains carbon monoxide which, when inhaled, interferes with transportation and utilization of oxygen throughout the body.

Environmental tobacco smoke

Cigarette smoke is called mainstream smoke when inhaled directly from a cigarette. Sidestream smoke is smoke emitted from the burning cigarette and exhaled by the smoker. Sidestream smoke is also called environmental tobacco smoke (ETS) or secondhand smoke. Inhalation of ETS is known as passive smoking. In 1993, the Environmental Protection Agency (EPA) classified ETS as a Group A (known human) carcinogen—the grouping reserved for the most dangerous carcinogens. By 1996, the Department of Health and Human Services’ Centers for Disease Control and Prevention (CDC) found that nine out of 10 non-smoking Americans are regularly exposed to ETS. A study by the American Heart Association reported in 1997 that women regularly exposed to ETS have a 91% greater risk of heart attack and those exposed occasionally a 58% greater risk—rates which are believed to apply equally to men. The EPA estimates that, annually, ETS is responsible for more than 3, 000 lung cancer deaths, 35, 000–62, 000 deaths from heart attacks, and lower respiratory tract infections (such as bronchitis [300, 000 cases annually] and asthma [400, 000 existing cases]), and middle ear infections in children.

ETS may be more carcinogenic than mainstream smoke as it contains higher amounts of carcinogenic materials with smaller particles. These smaller particles are more likely to lodge in the lungs than the larger particles in mainstream smoke. Researchers found that no safe threshold exists for exposure to ETS. With this information, many municipal governments and workplaces have banned cigarette smoking altogether.

The health consequences of tobacco use

Scientific evidence has proven that smoking can cause cancer of the lung, larynx, esophagus, mouth, and bladder; cardiovascular disease; chronic lung ailments; coronary heart disease; and stroke. Smokeless tobacco has equally deadly consequences. When cigarette smoke is inhaled, the large surface area of the lung tissues and alveoli quickly absorb the chemical components and nicotine. Within one minute of inhaling, the chemicals in the smoke are distributed by the bloodstream to the brain, heart, kidneys, liver, lungs, gastrointestinal tract, muscle, and fat tissue. In pregnant women, cigarette smoke crosses the placenta and may affect fetal growth.

Cardiovascular disease

Cardiovascular disease, or diseases of the blood vessels and heart, includes stroke, heart attack, peripheral vascular disease, and aortic aneurysm. In 1990 in the United States, one fifth of all deaths due to cardiovascular disease were linked to smoking. Specifically, 179, 820 deaths from general cardiovascular disease,

134, 235 deaths from heart disease, and 23, 281 deaths from cerebrovascular disease (stroke) were directly linked to smoking. In addition, researchers have noted a strong dose-response relationship between the duration and extent of smoking and the death rate from heart disease in men under 65. The more one smokes, the more one is likely to develop heart disease. Researchers have also seen a similar trend in women.

Cigarette smoking leads to cardiovascular disease in a number of ways. Smoking damages the inside of the blood vessels, initiating changes that lead to atherosclerosis, a disease characterized by blood vessel blockage. It also causes the coronary arteries (that supply the heart muscle with oxygen) to constrict, increasing vulnerability of the heart to heart attack (when heart muscle dies as a result of lack of oxygen) and cardiac arrest (when the heart stops beating). Smoking also raises the levels of low-density lipoproteins (the so-called “bad” cholesterol) in the blood, and lowers the levels of high-density lipoproteins (the so-called “good” cholesterol), a situation that has been linked to atherosclerosis. Finally, smoking increases the risk of stroke by 1.5 to 3 times the risk for nonsmokers.

Cancer

Smoking causes 85% of all lung cancers and 14% of all cancers—among them cancers of the mouth, pharynx (throat), larynx (voice-box), esophagus, stomach, pancreas, cervix, kidney, ureter, and bladder. More than 171, 500 new diagnoses were expected in 1998. Other environmental factors add to the carcinogenic qualities of tobacco. For example, alcohol consumption combined with smoking accounts for three-quarters of all oral and pharyngeal cancers. Also, persons predisposed genetically to certain cancers may develop cancer more quickly if they smoke. Only 14% of lung cancer patients survive five years after diagnosis.

Lung disease

Smoking is the leading cause of lung disease in the United States. Among the direct causes of death are pneumonia, influenza, bronchitis, emphysema, and chronic airway obstruction. Smoking increases mucus production in the airways and deadens the respiratory cilia, the tiny hairs that sweep debris out from the lungs. Without the action of the cilia, bacteria and inhaled particles from cigarette smoke are free to damage the lungs.

In the smaller airways of the lungs—the tiny bronchioles that branch off from the larger bronchi—chronic inflammation is present in smokers which causes airway to constrict causing cough, mucus production, and shortness of breath. Eventually, this inflammation can lead to chronic obstructive pulmonary disease (COPD), a condition in which oxygen absorption by the lungs is greatly reduced, severely limiting the amount of oxygen transported to body tissues.

Other health problems

For the 40 years prior to 1987, breast cancer was the leading cause of cancer death among women in the United States. In 1987, lung cancer took the lead. As well as increased risk of cancer and cardiovascular disease, women smokers are at increased risk of osteoporosis (a disease in which bones become brittle and vulnerable to breakage), cervical cancer, and decreased fertility. Pregnant women have increased risk for spontaneous abortion, premature separation of the placenta from the uterine wall (a life-threatening complication for mother and fetus), placenta previa (in which the placenta implants much lower in the uterus than normal, which may lead to hemorrhage), bleeding during pregnancy, and premature rupture of the placental membranes (which can lead to infection). Infants born to women who smoke during pregnancy are at increased risk for low birth weight (18, 600 cases annually), and other developmental problems. In men, smoking lowers testosterone levels, and appears to increase male infertility.

Numerous other health problems are caused by smoking such as poor circulation in the extremities due to constricted blood vessels. This not only leads to constantly cold hands and feet, it often requires amputation of the lower extremities. Smoking also deadens the taste buds and the receptors in the nasal epithelium, interfering with the senses of taste and smell, and may also contribute to periodontal disease.

Nicotine—addiction or habit?

In 1992, the Surgeon General of the United States declared nicotine to be as addictive as cocaine. An article published in the December 17, 1997 issue of the Journal of the National Cancer Institute stated nicotine addiction rates are higher than for alcohol or cocaine—that of all people trying only one cigarette, 33–50% will ultimately become addicted. The article concluded that simply knowing the harmful effects of tobacco is insufficient to help people kick the addiction and that behavioral intervention and support methods similar to those applied in alcohol and drug addictions appear to be most helpful.

The physical effects of cigarette smoke include several neurological responses which, in turn, stimulate emotional responses. When serotonin, a neuro-transmitter (substances in the brain used by cells to transmit nerve impulses) is released, a person feels more alert. Nicotine stimulates serotonin release. Soon, however, serotonin release becomes sluggish without the boost from nicotine and the smoker becomes dependent on nicotine to prompt the release of serotonin. Other neurotransmitters released in response to nicotine include dopamine, opioids (naturally occurring pain-killing substances), and various hormones, all of which have powerful effects on the brain where addiction occurs.

Genes and nicotine addiction

In 1998, scientists found a defective gene which makes the metabolism of nicotine difficult. The normal gene produces a liver enzyme needed to break down nicotine. The defective gene, found in about 20% of nonsmokers, may lessen the likelihood of nicotine addiction.

In 1999, researchers discovered a version of a gene which increases the levels of dopamine in the brain. Because nicotine stimulates the release of dopamine, researchers believe the new-found gene may reduce the individual’s desire to “pump up” dopamine production with nicotine.

The effects of quitting

Quitting smoking significantly lowers the risk of cancer and cardiovascular disease. In fact, the risk of lung cancer decreases from 18.83 times the rate of nonsmokers at one to four years after quitting, to 7.73 at five to nine years, to below 5 at 10–19 years, to 2.1 at 20-plus years. The risk of lung cancer for nonsmokers is 1.

Weight gain is a common side effect of quitting, since smoking interferes with pancreatic function and carbohydrate metabolism, leading to a lower body weight in some people. However, not all people experience this lowered body weight from smoking; thus, not all people who quit gain weight. Taste buds and smell are reactivated in nonsmokers, which may lead to increased food intake.

Methods of treatment

About 80% of people who quit relapse within the first two weeks. Less than 3% of smokers become non-smokers annually. Nicotine gum and patches, which maintain a steady level of nicotine in the blood, have met with some success but are more successful when combined with other support programs. Researchers now believe that smoking may be linked to depression, the withdrawal symptom causing most people who quit to begin again. In 1997, the FDA approved the antidepressant medication bupropion to help treat nicotine dependence.

Offense is the best defense

In 1998, a $206 billion settlement from tobacco companies to 46 states included a ban on all outdoor advertising of tobacco products. In 1999, the CDC appropriated more than $80 million to curtail tobacco use among young people. Coordinated education and prevention programs through schools have lowered the onset of smoking by 37% in seventh-grade students alone.

See also Respiratory system.

Resources

Periodicals

The Centers for Disease Control and Prevention (U.S.Government). “Cigarette Smoking Among Adults-United States, 2004.” Journal of the American Medical Association. 295 (2005): 749-751.

Godtfredson, Nina S., et al. “Effect of Smoking Reduction on Lung Cancer Risk.” Journal of the American Medical Association. 294 (2005): 1505-1510.

Other

U.S. Department of Health and Human Services. “The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General.” June 27, 2006.<http://www.surgeongeneral.gov/library/secondhandsmoke/report/fullreport.pdf> (accessed 2006).

U.S. Department of Health and Human Services. “The Health Consequences of Smoking: A Report of the Surgeon General.” 2004. <http://www.cdc.gov/tobacco/sgr/sgr_2004/chapters.htm> (accessed October 21, 2006).

World Health Organization. “The Tobacco Atlas.” 2004<http://www.who.int/tobacco/statistics/tobacco_atlas/en/> (accessed October 21, 2006).

Kathleen Scogna