Tobacco Documents Online

.. r. .. .. .. s .. r .. .. m.= r .. r m.. mw) I Suggested Citation U.S. Department of Health and Human Serviceti. Thr Hi,alllt Bc•iu!/il.c ()(Smnk- inigCessatian. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health. DHHS Publication No. (CDC) 90-8416, 19y0. a report of the Surgeon General 1990 The Health Benefits of SMOKING CESSATION ~ U.S. DEPAR fMGN fOF ItI:AI:I II ANI) IItIMAN SIiRVI('IiS Public I leallh Service CEHIER! FOH DIBFA$E CONLHOI ~ / Cenler% for Disease Control ~ ( Center for Chronic Disease Prevention and 1lcaltlt Promotiom Office on Smoking and Health Roukville. Maryland 20857 TGZOOM99

... r. .. .. .. a. .. .. r. .. = +.. a.. r .. M .r .. W FOREWORD M*Jiyi' MV More than 38 million Americans have quit smokinp cigarettes, and nearly half of all living adults who ever smoked have quit. Unfortunately, some 50 million Americans continue to smoke cigarettes, despite the many health education programs and anti- smoking campaigns that have been conducted during the past quarter century, despite the declining social acceptability of smoking, and despite the consequences of smoking to their health. Twenty previous reports of the Surgeon General have reviewed the health effects of smoking. Scientific data are now available on the consequences of smoking cessation for most smoking-related diseases. Previous reports have considered some of these data, but this Report is the first to provide a comprehensive and unified review of this topic. The major conclusions of this volume are: 1. Smokingce.ssation has major and immediate health benefits for men and women of all ages. Benefits apply to persons with and without smoking-related disease. 2. Former smokers live longer than continuing smokers. For example, persons who quit smoking before age 50 have one-half the risk of dying in the next 15 years compared with continuing smokers. 3. Smoking cessation decreases the risk of lung cancer, other cancers, heart attack, stroke, and chronic lung disease. 4. Women who stop smoking before pregnancy or during the first 3 to 4 months of pregnancy reduce their risk of hacing a lo%s birth.ceight baby to that of women who never smoked. 5. The health benefits of smoking cessation far exceed any risks from the average 5-pound (2.3-kg) weight gain or any adverse psychological effects that may follow quitting. With the long-standing evidence that smoking is extremely harmful to health and the mounting evidence that smoking cessation confers major health benefits, we remain faced with the task of developing effective strategies to curtail the use of tobacco. Two broad categories of intervention are available: prevention of smoking initiation among youth and smoking cessation. Resources for tobacco control are limited, and poiicymakers must decide how best to allocate those resources to smoking prevention and cessation. The goal of public health is to intervene as early as possible to prevent disease, disability, and premature death. From that standpoint, prevention of smoking initiation

~ ~ ~ ~ ~ ~ ~ '~lfould'~?i majorrrity. More than M:i,q)0 teenagers become regular smokers eurlr thi ~in the United States. Because of the strength of nicotine addiction, sonie have argued that public health efforts should focus on smoking prevention rather than smoking cessation. However, this need not be an "either-or" situation. Public health practitioners have categorized interventions into primary, secondary, and tertiary prevention. Primary prevention generally refers to the elimination of risk factors for disease in asymptomatic persons. Secondary prevention is defined as the early detection and treatment of disease, and is practiced using tools such as Pap smears and blood pressure screening. Tertiary prevention consists of measures to reduce impairment, disability, and suffering in people with existing disease. Smoking cessation falls under the category of primary prevention as does the prevention of smoking initiation. Smoking cessation meets the definition of primary prevention by reducing the risk of morbidity and premature mortality in asymptomatic people. In addition, parents who quit smoking reduce or eliminate the risk of passive- smoking-related disease among their children and reduce the probability that their children will become smokers. Thus, there should be no debate about the need for smoking prevention versus cessation-both are important. Public awareness of the health eff ects of smoking has increased substantially through the years. Nevertheless, important gaps in public knowledge still exist. Sonie smokers may have failed to quit because of a lack of appreciation of the health hazards of smoking and the benefits of quitting. In the 1987 National Health Interview Survey of Cancer Epidemiology and Control, respondents were asked whether smoking increases the risk of various diseases (lung cancer, cancer of the mouth and throat, heart disease, emphysema, and chronic bronchitis) and whether smoking cessation reduces the risk. Thirty to forty percent of smokers either did not believe that smoking increases these risks or did not believe that cessation reduces these risks. These proportions correspond to 15 to 20 million smokers in the United States. Clearly, our efforts to educate the public on the health hazards of smoking and the benefits ofquitting are not yet complete. As we continue and intensfy our efforts to inform the public of these findings, we must make available smoking cessation programs and services to those who need them. Although 90 percent of former smokers quit without using smoking cessation programs, counseling, or nicotine gum, smokers who do need this assistance should have it available. We endorse the view expressed in the Preface to the 1988 Surgeon General's Report that treatment of nicotine addiction should be considered at least as favorably by third-party payors as treatment of alcoholism and illicit drug addiction. Good smoking cessation treatments can achieve abstinence rates of 20 to 40 percent at I-year followup. Those success rates. combined with (he enormous health benefits of smoking cessation, would likely make payment for some smoking cessation treatments cost- beneficial. For example, research by the Centers for Disease Control suggests that a smoking cessation program offered to all pregnant smokers could save $5 for every dollar spent by preventing low birthweight-associated neonatal intensive care and long-term care. moQv9vog - ' - = M M M M r W This Report should galvanize the health community to stress repeatedly at everY opportunity the value of smoking cessation to the 50 million Americans who continue to smoke. James 0. Mason, M.D., Dr.P.H. Assistant Secretary for Health Public Health Service William L. Roper. M.D. Director Centers for Disease Control

.. m.. ... a. .. i.. = r ... m.m m ... .. m.. ... or. PREFACE This Report of the Surgeon General is the 21 st Report of the U.S. Public Healti; Service on the health consequences of smoking and the first issued during my tenure as Surgeon General. Whereas previous reports have focused on the health effects of smoking, this Report is devoted to the benefits of smoking cessation. The public health impact of smoking is enormous. As documented in the 1989 Surgeon General's Report, an estimated 390,000 Americans die each year from diseases caused by smoking. This to11 includes 115.000 deaths from heart disease; 106,(>(}0 from lung cancer: 31,600 from other cancers; 57,000 from chronic obstructive pulmonary disease: 27,500 from stroke; and 52,900 from other conditions related to smoking. More than one of every six deaths in the United States are caused by smoking. For more than a decade the Public Health Service has identified cigarette smoking as the most important preventable cause of death in our society. It is clear, then, that the elimination of smoking would yield substantial benefits for public health. What are the benefits, however, for the individual smoker who quits? A large body of evidence has accumulated to address that question and derives from cohort and case-control studies, cross-sectional surveys, and clinical trials. In studies of the health effects of smoking cessation, persons classified as former smokers may include some current smokers; this misclassification is likely to cause an underestimation of the health benefits of quitting. Taken together, the evidence clearly indicates that smoking cessation has major and immediate health benefits for men and women of all ages. Overall Benefits of Smoking Cessation Vs9ooVM9 People who quit smoking live longer than those who continue to smoke. To what extent is a smoker's risk of premature death reduced after quitting smoking? The answer depends on several factors, including the number of years of smoking, the number of cigarettes smoked per day, and the presence or absence of disease at the time of quitting. Data from the American Cancer Society's Cancer Prevention Study 11 (CPS-11) were analyzed in this Report to estimate the risk of premature death in ex-smokers versus current smokers. These data show, for example, that persons who quit smoking before age 50 have one-half the risk of dying in the next 15 years compared with continuing snrokers. Smoking cessation increases Iife expectancy because it reduces the risk of dying from specific smoking-related diseases. One such disease is lung cancer, the most common cause of cancer death in both men and women. The risk of dying from lung cancer is V

N1i= i~ i I~ i i ~ 22 times higher among male smokers and 12 times higher among female smokers compared with people who have never smoked.The risk of lung cancer declines steadily in people who quit smoking; after 10 years of abstinence. the risk of lung cancer is about 30 to 50 percent of the risk for continuing smokers. Smoking cessation also reduces the risk of cancers of the larynx, oral cavity, esophagus, pancreas, and urinary bladder. Coronary heart disease (CHD) is the leading cause of death in the United States. Smokers have about twice the risk of dying from CHD compared with lifetime nonsmokers. This excess risk is reduced by about half among ex-smokers after only I year of smoking abstinence and dcclines gradually thereafter. After 15 years of abstinence the risk of C:HD is similar to that of persons who have never smoked. Compared with lifetime nonsmokers, smokers have about twice the risk of dying from stroke, the third leading cause of death in the United States. Atter quitting smoking, the risk of stroke returns to the level of people who have never snroked; in some studies this reduction in risk has occurred within 5 years, but in others as long as 15 years of abstinence were required. Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD). the fifih leading cause of death in the United States. Smoking increases the risk ofCOPD by accelerating tlre age-related decline in lung function. With sustained abstinence from smoking, the rate of decline in lung function among former smokers returns to that of never smokers, thus reducing the risk of developing COPD. Influenza and pneumonia represent the sixth leading cause of death in Ihe United States. Cigarette smoking increases the risk of respiratory infections such as influenza, pneumonia, and bronchitis, and smoking cessation reduces the risk. Cigarette smoking is a major cause of peripheral ariery occlusive disease. This condition causes substantial mortality and morbidity; complications may include inter- mittent claudication, tissue ischernia and gangrene, and ultimately, loss of limb. Smoking cessation substantially reduces the risk of peripheral artery occlusive disease compared with continued sntoking. The mortality rate from abdominal aortic aneurysm is two to five times higher in current smokers than in never smokers. Former sniokers have half the excess risk of dying from this condition relative to current snrokers. About 2(1 million Americans currently have, or have had, an ulcer of the stomach or duodenum. Smokers have an increased risk of developing gastric or duodenal ulcers, and this increased risk is reduced by quitting smoking. Benefits at All Ages According to a 1989 Gallup survey, the proportion of smokers who say they would like to give up snroking is lower for smokers aged 50 and older (57 percent) than for smokers aged 18-29 (68 percent) and 30-49 (67 percent). Older smokers may be less nrotivated to quit smoking because the highly motivated may have quit already at younger ages. leaving a relatively "hard-core" group of ulder smokers. But many long-tenn smokers may lack motivation to quit for other reasons. Some nray believe they are no longer at risk of smoking-related diseases because they have already survived smoking for many years. Others may believe that any damage that may have i i ! i i i M i = M been caused by smoking is irreversible after decades of smoking. For similar reatioirs. many physicians may be less likely to counsel their older patients to quit. CPS-11 data were used to estimate the effects of quitting smoking at various ages on the cumulative risk of death during a fixed interval after cessation. The results show that the benefits of cessation extend to quitting at older ages. For example, a healthy man aged 60-64 who smokes I pack of cigarettes or more per day reduces his risk of dying during the next 15 years by 10 percent if he quits smoking. I These findings support the recommendations of the Surgeon General s IyxR Workshop on Health Promotion and Aging for the development and etissemination (.f smoking cessation messages and interventions to older persons. I am pleased that a coalition of organizations and agencies is now working toward implementation of those recommendations, including the Centers for Disease Control; the National Cancer Institute; the National Heart, Lung, and Blood Institute; the Administration on Aging,; the Department of Veterans Affairs; the Office of Disease Preveittion and Health Promotion; the American Association of Retired Persons; and the Fox Chase Cancer Center. The major message of this campaign will he that it is never too late to quit smoking. Two facts point to the urgent need for a strong smoking cessation canipaign targeting older Americans: (1) 7 mi Ilion smokers are aged 60 or older; and (2) smoking is a niajor risk factor for 6 of the 14 leading causes of death among those aged 60 and older, and is a complicating factor for 3 others. Benefi.ts for Smokers with Existing Disease Many smokers who have already developed smoking-related disease or symptoms may be less motivated to quit because of a belief that the damage is already done. For the same reason, physicians may be less motivated to advise these patients to quit. However, the evidence reviewed in this Report shows that smoking cessation yields important health benefits to those who already suffer from smoking-related illness. Among persons with diagnosed CHD. smoking cessation markedly reduces the risk of recurrent heart attack and cardiovascular death. In many studies, this reduction in risk has been 50 percent or more. Smoking cessation is the nrost important intervention in the management of peripheral artery occlusive disease; for patients with this condi- tion, quitting smoking improves exercise tolerance, reduces the risk of amputation peripheral artery surgery, and increases overall survival. Patients with gastric and duodenal ulcers who stop smoking improve their clinical course relative to smokers who continue to smoke. Although the benefits of smoking cessation among stroke patients have not been studied, it is reasonable to assume that quitting smoking reduces the risk of recurrenl stroke just as it reduces the risk of recurrence of othercardiovascul.r events. Even smokers who have already developed cancer may benefit from smoking cessation. A few studies have shcrwn that persons who stopped smoking after diagnosis of cancer had a reduced risk of acquiring a second primary cancer compared a-ith persons who continued to smoke. Although relevant data are sparse, longer survival might be expected among smokers with cancer or other serious illnesses if they stop vi

M M,m ..~ s r ~ No ~ -~ an W ~ tr.c- ~ ~ ~ ~. ~ smoking. Smoking cessation reduces the risk of respiratory infections such as pneumonia, which are often the immediate causes of death in patients with an under- lying chronic disease. The important role of health care providers in counseling patients to quit smoking is well recognized. Health care providers should give smoking cessation advice and assistance to all patients who smoke, including those with existing illness. Benefits for the Fetus Benefits for Infants and Children As a pediatrician. I am particularly concemed about the effects of parental smoking on infants and children. Evidence reviewed in the 1986 Surgeon General's Report. T>+te Heallh CGmseqrrenre.c t?f Im•nlunlary Smoking, indicates that the children of parents who smoke, compared with the children of nonsmoking parents, have an increased frequency of respiratory infections such as pneumonia and bronchitis. Many studies have found a dose-response relationship between respiratory illness in children and their level of tobacco smoke exposure. Several studies have shown that children exposed to tobacco smoke in the home are more likely to develop acute otitis media and persistent middle ear effusions. Middle ear disease impmes a substantial burden on the heaUh care system. Otitis media is the most frequent diagnosis made by physicians who care for children. The myringotomy- and-tube procedure, used to treat otitis media in more than I million American children each year, is the most common minor surgical operation performed under general anesthesia. The impact of smoking cessation during or after pregnancy on these associations has not been studied. flowever, the dose-response relationship between parental smoking and frequency of childhood respiratory infections suggests that smoking cessation during pregnancy and abstinence after delivery would eliminate most or all of the excess risk by eliminating most or all of the exposure. If parents are unwilling to quit smoking for their own sake, I would urge them to quit for the sake of their children. Passive-smoking-induced infections in infants and year.g children can cause serious and even fatal illness. Moreover, children whose parents smoke are much more likely to become smokers themselves. Maternal smoking is associated with several complications of pregnancy including abruptio placentae, placenta previa, bleeding during pregnancy, premature and prolonged rupture of the membranes, and preterm delivery. Maternal smoking retards fetal growth, causes an average reduction in birthweight of 200 g, and doubles the risk of having a low birthweight baby. Studies have shown a 25- to 50-percent higher rate of fetal and infant deaths among women who smoke during pregnancy compared with those who do not. Women who stop smoking before becoming pregnant have infants of the same birthweight as those born to women who have never smoked. The same benefit accrues to women who quit smoking in the first 3 to 4 months of pregnancy and who remain abstinent throughout the remainder of pregnancy. Women who quit smoking at later stages of pregnancy, up to the 30th week of gestation, have infants with higher birthweight than do women who smoke throughout pregnancy. Smoking is probably the most important modifiable cause of poorpregnancy outcome among women in the United States. Recent estimates suggest that the elimination of smoking during pregnancy could prevent about 5 percent of perinatal deaths, about 20 percent of low birthweight births, and about 8 percent of preterm deliveries in the United States. In groups with a high prevalence of smoking (e.g., women who have not completed high school), the elimination of smoking during pregnancy could prevent about 10 percent of perinatal deaths, about 35 percent of low hirthweight births, and about 15 percent of preterm deliveries. The prevalence of smoking during pregnancy has declined over time but remains unacceptably high. Approximately 30 percent of U.S. women who are cigarette smokers quit after recognition of pregnancy, and others quit later in pregnancy. However, about 25 percent of pregnant women in the United States smoke throughout pregnancy. A shocking statistic is that half of pregnant women who have not completed high school smoke throughout pregnancy. Many women who do not quit smoking during pregnancy reduce their daily cigarette consumption; however, reduced con- sumpt:,:n without quitting may have little or no benefit for birthweight. Of the women who quit smoking during pregnancy, 70 percent resume smoking within I year of delivery. Initiatives have been launched in the public and private sectors to reduce smoking during pregnancy. These programs should be expanded, and less educated pregnant women should be a special target of these efforts. Strategies need to be developed to address the problem of relapse after delivery. 9V (~~ 'J 0,Y + 1 IV J (.! I Smoking Cessation and Weight (:ain The fear of postcessation weight gain may discourage many smokers from trying to quit. The fear or occurrence of weight gain may precipitate relapse among many of those who already have quit. In the 1986 Adult Use ofTobacco Survey. current smokers who had tried to quit were asked to judge the importance of several possible reasons for their return to smoking. Twenty-seven percent reported that "actual weight gain" was a "very important" or "somewhat important" reason why they resumed smoking; 22 percent said that "the possibility of gaining weight" was an important reason for their relapse. Forty-seven percent of current smokers and 48 percent of former smokers agreed with the statement that "smoking helps control weight." Fifteen studies involving a total of 20,(HK) persons were reviewed in this Report t,, determine the likelihood of gaining weight and the average weight gain after quitting. Although four-fifths of smokers who quit gained weight after cessation, the average weight gain was only 5 pounds (2.3 kg). The average weight gain among subjects who continued to smoke was I pound. Thus, smoking cessation produces a 4-pound greater weight gain than that associated with continued smoking. This weight gain pose% a minimal health risk. Moreover, evidence suggests that this small weight gain is accompanied by favorable changes in lipid profiles and in body fat distribution.

~ ~ ~ 'SfRirkin~ation M M ~ ~ ~1ratns-and messages should emphasize that weight gain after quitting is small on average. Not only is the average postcessation weight gain small, but the risk of large weight gain after quilting is extremely low. Less than 4 percent of those who quit smoking gain more than 20 pounds. Nevertheless, special advice and assistance should be available to the rare person who does gain considerable weight after quitting. For these individuals, the health benefits of cessation still occur, and weight control programs rather than smoking relapse should be implemented. Increases in food intake and decreases in resting energy expenditure are largely responsible for postcessation weight gain. Thus, dietary advice and exercise should be helpful in preventing or reducing postcessation weight gain. Unfortunately, minor weight control modifications to smoking cessation programs do not generally yield beneficial effects in terms of reducing weight gain or increasing cessation rates. A few studies have investigated pharmacofogic approaches to postcessation weight control; preliminary results are encouraging but more research is needed. High priority should be given to the development and evaluation of effective weight control programs that can be targeted in a cost-effective manner to those at greatest need of assistance. Psychological and Behavioral Consequences of Smoking Cessation Nicotine withdrawal symptoms include anxiety, irritability, frustration, anger, dif- ficulty concentrating, increased appetite, and urges to smoke. With the possible exception of urges to smoke and increased appetite, these effects soon disappear. Nicotine withdrawal peaks in the first I to 2 days following cessation and subsides rapidly during the following weeks. With long-term abstinence, fonner smokers are likely to enjoy favorable psychological changes such as enhanced self-esteem and increased sense of self control. Although most nicotine withdrawal symptoms are short-lived, they often exert a strong influence on smokers' ability to quit and maintain abstinence. Nicotine withdrawal may discourage many smokers from trying to quit and may precipitate relapse among those who have recently quit. In the 1986 Adult Use of Tobacco Survey. 39 percent of' current smokers reported that irritability was a "very important" or "somewhat important" reason why they resumed smoking after a previous quit attempt. Smokers and ex-smokers should be counseled that adverse psychological effects of smoking subside rapidly over time. Smoking cessation materials and programs, nicotine replacement, exercise, stress management, and dietary counseling can help smokers cope with these symptoms until they abate, after which favorable psychologi- cal changes are likely to occur. Support for a Causal Association Between Smoking and 1)isease Tens of thousands of studies have documented the associations between cigarette smoking and a large number of serious diseases. It is safe to say that sntoking represents the most extensively documented cause of disease ever investigated in the history of biomedical research. +~ #= 4M M IM ~ ~ ~ 4M P! Previous Surgeon General's reports, in particular the landmark tyo4 Report of the Surgeon General's Advisory Committee on Smoking and Health and the 1982 Surgeon General's Report on smoking and cancer, examined these associations with respect 10 the epidemiologic criteria forcausality. These criteria include the consistency, strength, specificity, coherence, and temporal relationship of the association. Based on these criteria, previous reports have recognized a causal association between smoking and cancers of the lung, larynx, esophagus, and oral cavity; heart disease; stroke; peripheral I artery occlusive disease: chronic obstructive pulmonary disease; and intrauternne growth retardation. This Surgeon General's Report is the first to conclude that the evidence is now sufficient to identify cigarette smoking as a cause of cancer of the urinary bladder; the 1982 Report concluded that cigarette smoking is a contributing factor in the development of bladder cancer. The causal nature of most of these associations was well established long before publication of this Report. Nevertheless, it is worth noting that the findings of this Report add even more weight to the evidence that these associations are causal. The criterion of coherence requires that descriptive epidemiologic findings on disease occurrence correlate with measures of exposure to the suspected agent. Coherence would predict that the increased risk of disease associated with an exposure would diminish or disappear after cessation of exposure. As this Report shows in great detail, the risks of most smoking-related diseases decrease after cessation and with increasing duration of abstinence. Evidence on the risk of disease after smoking cessation is especially important for the understanding of sntoking-and-disease associations of unclear causality. For ex- ample, cigarette smoking is associated with cancer of the uterine cervix, but this association is potentially confounded by unidentified factors (in particular by a sexually transmitted etiologic agent). The evidence reviewed in this Report indicates that former smokers experience a lower risk of cervical cancer than current smokers, even after adjusting for the social correlates of smoking and risk of sexually acquired infections. This diminution of risk after smoking cessation supports the hypothesis that smoking is a contributing cause of cervical cancer. Conclusion The Comprehensive Smoking Education Act of 1984 (Public Law 98-474) requires the rotation of four health warnings on cigarette packages and advertisements. One of those warnings reads. "SURGEON GENERAL'S WARNING: Quitting Smoking Now Greatly Reduces Serious Risks to Your Health." The evidence reviewed in this Report confirms and expands that advice. The health benefits of quitting smoking are immediate and substantial. They far exceed any risks from the average 5-pound weight gain or any adverse psychological effects that may follow quitting. The benefits extend to men and women, to the young and the old, to those who are sick and to those who are well. Smoking cessation represents the single most important step that smokers can take to enhance the length and quality of their lives.

-'-hcion- i' ~ M M ~ ~ ~ ~ ~ ~ ~ ~.~ 1~ M ~ '~ ~ Pub p po is tell us that most smokers want to quit. This Report provides smokers with new and more powerful motivation to give up this self-destructive behavior. ACKNOWLEDGMENTS Antonia C. Novello. M.D.. M.P.H. Surgeon General M'3 V Y:,7 Y.7 9 This Report was prepared by the Department of Health and Human Services under the general editorship of the Office on Smoking and Health, Ronald M. Davis, M.D•, , Director. The Managing Editor was Susan A. Hawk, Ed.M., M.S. Tlte sc•ic•iUific editrnv.c n(the Reprn•t were: Jonathan M. Samet, M.D. (Senior Scientific Editor), Professor of Medicine and Chief, Pulmonary Division. Department of Medicine and the New Mexico Tumor Registry. Cancer Center, University of New Mexico, Albuquerque, New Mer ico Ronald M. Davis, M.D., Director, Office on Smoking and Health, Center for Chronic Disease Prevention and Health Promotion (CCDPHP), Centers for Disease Control (CDC). Rockville, Maryland Neil E. Grunberg, Ph.D., Professor, Department of Medical Psychology, Uniformed Services University of the Health Sciences, Bethesda, Maryland Judith K. Ockene. Ph.D., Professor of Medicine, and Director, Division of Preventive and Behavioral Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester. Massachusetts Diana B. Petitti, M.D., M.P.H., Associate Professor, Department of Family and Com- munity Medicine, University of California at San Francisco. School of Medicine, San Francisco, California Walter C. Willett, M.D., Dr.P.H., Professor of Epidemiology and Nutrition, Harvard School of Public Health, and The Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Mas- sachusetts • The foNrnrin,q indiridiiaLc prepared draft chapters or portions of the Report: Robert Anda, M.D., Epidemiologist. Office of Surveillance and Analysis, CCDPHP; CDC. Atlanta, Georgia John Baron, M.D.. Associate Professor of Medicine, Department of Medicine. Dartmouth Medical School, Hanover, New Hampshire Tim Byers, M.D.. M.P.H., Chief, Epidemiology Branch, Division of Nutrition. CCDPHP, CDC. Atlanta. Georgia Arden G. Christen, D. D.S., M.S.D., M.A., Chairman, Professor, Department of Preven- tive and Community Dentistry, Indiana University School of Dentistry, Indianapolis, Indiana Graham Colditz, Dr.P.H., Assistant Professor of Medicine, Harvard School of Public Health, and the Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts xii