Introduction

Cigarette smoking is responsible for at least 85% of the cases of lung cancer in this country. It is also directly related with cancer of the larynx, oral cavity, pancreas and bladder. Smoking is the principal cause of 80%-90% of the cases of chronic obstructive respiratory conditions and a major risk factor in coronary heart disease.

Cigarettes and cigarette smoke contain thousands of chemical compounds including nicotine, tar, carbon monoxide, benzo(a)pyrene and nitrosamines and particulates. Some of these are proven or suspected carcinogens. These substances are inhaled from a cigarette (mainstream smoke) and are released into the air by the smoker's exhalation and directly from the burning end of the cigarette (side-stream smoke). This smoke contributes significantly to the level of indoor air pollution. Independently or together these substances may cause adverse biological changes in the body.

These substances are harmful to the smoker and may also harm nonsmokers in a smoker's environment. Smoking has been shown to be associated with low birthweight and increases the risk of spontaneous abortion, fetal death and neonatal death.

Children of parents who smoke have a higher incidence of respiratory problems. In young children, the harmful effects of cigarette smoke are increased because they breathe more rapidly than adults, taking in more air and pollution in comparison to their body weight.

The danger of passive smoking to the individual who lives or works with smokers is less clear, although three epidemiological studies have shown increased cancer risks for wives of spouses who smoke. In two of the three, the difference was considered statistically significant. Other problems arising from passive smoking range from minor eye and throat irritations to anginal attacks in some individuals suffering from coronary artery disease.

The amount of smoke in a room depends upon many factors, such as the size of the room, number of smokers, amount smoked, ventilation and air conditioning. The number and changing nature of the variables make measurement of harmful substances and identification of their contributors difficult. It is known, however, that carbon monoxide, one of the harmful elements released in smoking, does not settle out of the atmosphere in a room and is not removed by most air filtration systems. This is of concern since the need to conserve energy has resulted in better-sealed buildings that recycle air.

Quitting smoking has definite health benefits. If a smoker quits smoking at the point when there have been early precancerous cellular changes in the lungs, the damaged bronchial lining may return to normal. The accelerated rate of decline in lung function with age experienced by smokers can be slowed. Ceasing smoking is helpful for those suffering from coronary heart disease. Giving up smoking early in a pregnancy reduces the risk of delivering a low birthweight baby almost to that of a nonsmoker.

Smoking is a powerful addiction that many find difficult to give up even in the face of known health hazards. In addition to the reinforcing' value of nicotine and other chemicals in tobacco, psychosocial factors such as peer pressure and stress are important in initiating and maintaining the habit. Research indicates, however, that 90% of smokers either have tried to quit or would like to quit.

Smoking cessation may be accomplished through an individual's unaided decision to quit, the use of a self-guided cessation program or participation in an organized cessation group program. Cessation methods include education with social support, aversive smoking, biofeedback, hypnosis and acupuncture. Nicotine gum has been used to wean smokers from their cigarettes.

Prevalence

The percentage of current adult smokers in the U.S. has declined since 1965, with the number of males who smoke decreasing, from an estimated 52.9% in 1964 to less than 33% in 1985. The percentage of female adult smokers was 28% in 1985, having declined from 34.1% in 1965.

Estimates from the 1985 National Health Interview Survey indicate that of smokers in 1985 31% of males and 23% of females were heavy smokers (25 + cigarettes per day). These figures represent an increase in male heavy smokers from 24.1% in 1965 and in females from 13% in 1965.

The High School Seniors Survey conducted by the National Institute on Drug Abuse has found that since 1975 the prevalence of cigarette smoking among adolescent females has exceeded that of males, despite a decline in smoking for both sexes since 1977.

The prevalence rate for female high school seniors in 1984 was slightly over 20%, while that for males was about 16%.

The Burden of Illness—Health Consequences

Mortality

Compared to nonsmokers, an average young male smoker (30-40 years of age) who smokes more than 40 cigarettes per day loses an estimated 8 years of life.

The mortality ratio for female smokers is 12 or 1.3 compared to nonsmokers. Mortality ratios increase with the amount of cigarettes smoked. The mortality ratio of the two-pack-a-day female smoker is 1.63.

Cancer

Smoking accounts for some 30% of all cancer deaths.

Cigarette smoking accounts for 25% of all cancer deaths in women.

The death rate from cancer for male cigarette smokers is more than double that of nonsmokers, and the rate for female smokers is 67% higher than for nonsmokers.

Smoking is responsible for 85% of lung cancer cases in men and 75% among women, according to estimates of the American Cancer Society.

Smoking is causally associated with cancer of the larynx, oral cavity, esophagus, kidney, and urinary bladder in women and men.

Chronic Obstructive Lung Disease (COLD)

Cigarette smoking is the major cause of COLD in the U.S. for both men and women.

60,000 Americans died in 1983 due to chronic obstructive respiratory conditions and estimates are that 80%-90% of the deaths are attributable to smoking.

Heavy smokers may face a risk of COLD 30 times that of nonsmokers.

Acute exposure to cigarette smoke results in an increase in airway resistance in both animals and humans.

Exposure to cigarette smoke results in an increase in pulmonary epithelial permeability in both humans and animals.

Cigarette smoke impairs elastin synthesis in vitro and elastin repair in vivo in experimental animals (elastin is a vital structural element of pulmonary tissue).

Death from COLD usually comes after an extended period of illness and disability with high costs in terms of medical care, lost wages and premature mortality.

Cardiovascular Disease

Cigarette smoking is a major cause of coronary heart disease in the U.S. for women and men.

Overall, cigarette smokers have a death rate from greater coronary heart disease 70% higher than nonsmokers, with heavy smokers (2 packs or more per day) experiencing CHD death rates between 2 and 3 times greater than nonsmokers.

The risk of sudden cardiac death is 2-4 times greater for smokers than for nonsmokers.

Cigarette smoking is associated with cerebrovascular disease primarily in the younger age groups.

Pregnancy and Infant Health

Babies born to women who smoke during pregnancy are, on the average 200 grams lighter than babies born to comparable, nonsmoking women. This is independent of other factors that influence birthweight. One study found that the risk of adjusted birthweights under 2,500 grams increased 53% for light smokers (less than 1 pack per day) and 130% for heavy smokers (1 pack per day or more) over that of nonsmokers.

Smoking has been found to result in fetal growth retardation demonstrated in a decrease in body length, chest circumference and head circumference.

The risk of spontaneous abortion, fetal death and neonatal death increases directly with increasing levels of maternal smoking during pregnancy.

Up to 14% of all preterm deliveries in the U.S. may be attributable to maternal smoking.

Studies in women suggest that cigarette smoking may impair fertility.

Children whose parents smoke experience more respiratory symptoms and have an increased frequency of bronchitis and pneumonia.

Interaction of Smoking with other Risk Factors

Cigarette smoking acts synergistically with other coronary heart disease risk factors resulting in a risk greater than the sum of the individual risks.

The risk of myocardial infarction in women smokers who use oral contraceptives is increased by a factor of approximately 10. They also face an increased risk of subarachnoid hemorrhage (stroke) when smoking is combined with use of oral contraceptives.

Excessive use of alcohol acts synergistically with smoking to increase the incidence of oral and laryngeal cancer.

Certain occupations combine the effects of cigarette smoking with exposure to toxic substances such as dust from cotton, silica and coal, fumes from rubber and chlorine and fibers from asbestos. Uranium miners who smoke also face increased cancer risk over nonsmoking miners.

Benefits of Cessation

Ex-smokers experience overall mortality ratios that decline as the number of years of cessation increases. The overall mortality ratios of ex-smokers after 15 years of cessation are similar to those of persons who have never smoked.

Cessation of smoking reduces the risk of lung cancer mortality compared to that of the person who continues to smoke.

The coronary heart disease death rate for ex-smokers compared to smokers declines rapidly after cessation. After some 3 years of not smoking, the coronary heart disease death rate for ex-smokers who consumed less than 1 pack a day is almost identical to that of life-long nonsmokers.

Giving up smoking can result in a reduction of the accelerated decline in respiratory function with age experienced by smokers, but evidence does not indicate that lost function can be regained.

A woman who gives up smoking by her fourth month of gestation reduces the risk of delivering a low birthweig, ht baby to a rate similar to that of a nonsmoker.

Smoking cessation improves the prognosis of arteriosclerotic peripheral vascular disease and has a favorable impact on vascular potency following reconstructive surgery.

The Burden of Illness—Economic Impact

The Office of Technology Assessment has estimated the direct health care and indirect productivity cost of smoking at between $38 and $95 billion. The median estimate is $65 billion, or $2.17 in lost productivity and health care costs per pack of cigarettes sold.

Absenteeism is 50% higher for smokers than for nonsmokers.

Job-related accidents are twice as high for smokers as for nonsmokers.

Smokers are 50% more likely to be hospitalized than those who do not smoke.

The insurance industry estimates that employers spend an average of $300 more in insurance claims for smokers than nonsmokers.

Special Issues

Adolescents

The strength of the smoking habit is so great that prevention of smoking in young people may be more effective in reducing smoking in the long-run than cessation efforts among the adult population.

Young women are particularly at risk from smoking because of its effects on the fetus in pregnancy and its adverse synergistic activity with oral contraceptives. Among 17-19 year olds, smoking prevalence is greater among women than men.

Young men may be more at risk from the synergistic action of cigarette smoking with another risk-behavior, excessive alcohol consumption. The CDC Behavioral Risk Factor Surveillance found 51.9% of males aged 18-24 years had engaged in binge drinking (5 or more drinks on a given occasion in the past month).

Another area of concern for youth is the use of smokeless tobacco, which is implicated in oral cancer. A 1986 report found an average first use of smokeless tobacco at 10 years of age and regular use at 12 years of age. 70% of the 290 respondents reported they tried to quit but were unsuccessful. More than 80% of those surveyed said they believed smokeless tobacco was safe to use.

Lower-Yield Tar and Nicotine Brands

In an effort to make the cigarette less dangerous, the lower-yield tar and nicotine brands were developed. Evaluating the relative health risks between regular brands and low-yield brands has proved to be difficult, because many smokers change their smoking behavior when they switch to the lower-yield brand. In an attempt to satisfy nicotine or taste demands, however, they may compensate by smoking more cigarettes than before, puffing more frequently, inhaling more deeply and for a longer period. This could lead to increased atherogenesis through the greater intake of carbon monoxide, hydrogen cyanide and nitrous oxide, all constituents of cigarette smoke. Thus, these compensatory behaviors associated with the switch to the lower-yield brands may result in a cigarette that, while less harmful for cancer etiology, may not reduce the risk for coronary disease.

While reducing the tar content in cigarettes appears to reduce the risk of cough and mucus hypersecretion in the lungs, the risk of shortness of breath and airflow obstruction that is more closely linked to the number of cigarettes smoked may not be reduced.

Another complicating factor in determining the health hazards of the lower-yield brands is that additives for flavoring or other uses in these brands have not been adequately identified and tested for adverse biological potential.

The use of filter cigarettes and cigarettes with lower-level tar and nicotine is correlated with a lower risk of cancer of the lung and larynx than use of high tar and unfiltered cigarettes, although it is still higher than that for nonsmokers. Overall mortality ratios for smokers of cigarettes with less than 1.2 mg. of nicotine and less than 17.6 mg. of tar still are 50% greater than for nonsmokers.

Steven Parker

Copyrighted material; do not reprint without permission.

 

View all articles by Steven Parker