Tobacco Documents Online

Cigarette Smoking and Chronic Obstructive Lung Diseases: The Major Gaps in Knowledge The Tobacco Institute, 1875 I Street Northwest, Washington, DC 20006 1984

Chronic Obstructive Lung Diseases What we know Chronic bronchitis and emphysema are the major components of the chronic non-neoplastic bronchopulmonary disease spectrum. This group of noncancerous lung diseases, which also includes asthma and some types of pneumonia, also is called chronic obstructive lung disease (COLD), chronic obstructive pulmonary disease (COPD) and chronic airflow obstruction (CAO). By any name, these conditions represent a major health problem in both industrial and developing nations. There is much we don't know about them. 1

The first U.S. Surgeon General's report on smoking and health, in ~ 1964, declared that cigarette smoking is the most important cause of chronic bronchitis in the United States. The authors wrote that although a relationship existed between pulmonary emphysema and cigarette smoking, it had not been established that the relationship was causal. They stated the need for "filling the major gaps'in knowledge about the relationships of smoking and chronic bronchopulmonary diseases." A problem inherent in filling those gaps in knowledge or in establishing a correlation of smoking or any other factor with chronic bronchitis or emphysema was explicit in the 1979 Surgeon General's report on smoking, the last to deal at length with the diseases. That problem is one of definition. Physicians often use these disease names interchangeably to describe a patient with chronic airflow obstruction, the report said. It noted that "the confusion between chronic bronchitis and emphysema has been compounded further by the manner in which they have been defined by various scientific societies, in different studies, and in different nations." The tobacco industry has not agreed with the judgment of the Surgeon General's reports that cigarette smoking has been established as a cause of chronic bronchitis. A causal relationship between 2 N CA O ~ ~ ~ W N -0 0

smoking and either chronic bronchitis or emphysema has not been established scientifically. Statistical correlation does not establish cause. It never has. What we do not know While the Surgeon General's annual reports on smoking have asserted that cigarette smoking is the principal cause of COLD and its major components, a discerning examination of the scientific literature worldwide reveals these points. 1. That the causes of COLD and its pathogenesis are multiple and at the present poorly defined. 2. That the current trend for combining chronic bronchitis and emphysema in a general category of COLD makes it extremely difficult to determine true incidence and mortality rates and may do little to encourage the average physician to pursue a more definitive diagnosis. This practice, furthermore, makes any statistical/epidemiologic study, retrospective or otherwise, difficult to evaluate. 3. That in fact there is scientific evidence from studies, some including smoking data, that other factors may be related to 3

the onset of COLD. Among these are genetic factors, familial and socioeconomic factors, occupational, environmental, infectious and nutritional factors, any or all of which may be operative in the pathogenesis of COLD. There are basic questions that -- notwithstanding the Surgeon General's reports -- remain unanswered today. o In view of the many factors, such as infection, air pollution, genetics and occupation, that have been associated with COLD, is the assertion that smoking is the primary cause of COLD opinion or fact? o Experiments using air pollutants, such as sulfur oxides and oxides of nitrogen, have produced emphysema in laboratory animals. Yet many animal experiments have failed to induce emphysema with long-term exposure to cigarette smoke. Why? o Recorded death rates for COLD increased in the United States almost one-quarter between 1969 and 1980. Cardiovascular death rates have dropped by an even larger amount. Yet the Surgeon General's reports have labeled cigarette smoking a major cause of both COLD and cardiovascular disease and the 1983 report suggested the improvement in cardiovascular mortality was in part due to a lower incidence of smoking. If smoking causes both COLD and 4

cardiovascular disease, how can one be going up and the other .down? o If smoking is a major cause of COLD, then why is it, as the British scientist Sir Charles Fletcher, a longtime opponent of smoking, wrote, that "most smokers suffer no substantial• obstructive damage"? Conclusion These scientific enigmas are but some of the many gaps in knowledge about cigarette smoking and COLD. Acceptance of smoking as the major cause may only discourage the additional research that is necessary to find the causes of these chronic diseases. N U1 O 1-Y ~ ~ W N -0 W 5

1. Aviado D., Testimony, U.S. Congress, Senate Committee on Labor and Human Resources, Smoking Prevention Health and Education Act of 1983, Hearing, 98th Congress, First Session, May 12, 1983 (Washington: Government Printing Office, 1983), pp. 258-278. 2. Burrows B., et al., "The Relationship of Childhood Respiratory Illness to Adult Obstructive Airway Disease," Am Rev Resp Dis 115: 751-760, 1977. 3. Fletcher C., et al., The Natural History of Chronic Bronchitis and Emphysema, Oxford Univ Press, Oxford, 1976, 272 pp. 4. Lebowitz M.D., "The Relationship of Socio-Environmental Factors to the Prevalence of Obstructive Lung Diseases and Other Chronic Conditions," J Chron Dis 30: 599-611, 1977. 5. Moser K.M., Bordow R.A., "Chronic Obstructive Pulmonary Disease: Definition, Epidemiology, and Pathology," in Manual of Clinical Problems in Pulmonary Medicine, Bordow R.A., et al. (eds.), Little, Brown and Company, Boston, 1980. 6. Openbrier D.R., et al., "Nutritional Status and Lung Function in Patients with Emphysema and Chronic Bronchitis," Chest 6

7. f Quanjer Ph.H., et al., "Maximal Expiratory Flow-Volume Curves in a Follow-Up Study," Scan J Resp Dis 57: 309-310, 1976. 8. Salvaggio J.E., "Overview of Occupational Immunologic Lung Disease," J Allergy Clin Immunol 70: 5-10, 1982. 9. Tager I., et al., "Studies of the Familial Aggregation of Chronic Bronchitis and Obstructive Airways Disease," Int J >; idemiol 7: 55-62, 1978. 10. Tisi G.M., Pulmonary Physiology in Clinical Medicine, Second Edition, Williams & Wilkins, Baltimore/London, 1983. 11. U.S. Public Health Service, Smoking and Health: Report of the Advisory Committee to the Surgeon General of the Public Health Service, DHEW, Pub. No. 1103, 1964. 12. U.S. Public Health Service, Smoking and Health: A Report of the Surgeon General, DHEW, Pub. No. (PHS)79-50066, 1979. 13. U.S. Public Health Service, The Health Consequences of Smoking, Cardiovascular Disease: A Report of the Surgeon General, 1983, DHHS, Pub. No. DHH(PHS) 84-50204. N cn 0 ~ ~ ~ w N 7 - c~n

14. U.S. Public Health Service, Advance Report of Final Mortality r Statistics, 1980, Monthly Vital Statistics Report, National Center for Health Statistics, Vol. 32, No. 4 (Sup.), Aug. 11, 1983. 8

Environmental Tobacco Smoke Exposure Just as no abnormal respiratory function has been reported in most smokers, it has been reported in some nonsmokers. But abnormal respiratory function, whether reported in smoker or nonsmoker, has not been scientifically established to be caused by cigarette smoke. With instruments and technologies available in recent years, researchers have measured varying levels of lung function when comparing groups of individuals -- whether of the same or widely varied ages, whether smokers and nonsmokers, or by degree of reported exposure to occupational and atmospheric factors, including environmental tobacco smoke (ETS). 9 N ttt O ~ A ~ W N ~ V