Perspectives in Disease Prevention and Health Promotion Leading Work-Related Diseases and Injuries--United States

The National Institute for Occupational Safety and Health (NIOSH) has developed a suggested list of the leading work-related diseases and injuries (Table 1). The first four categories have been described previously (1-4); a discussion of the fifth category, "Cardiovascular Diseases," appears below. CARDIOVASCULAR DISEASES

Cardiovascular diseases, including hypertensive disease (International Classification of Diseases 9th Revision (ICD) codes 401-405), ischemic heart disease (ICD codes 410-414), other forms of heart disease (ICD codes 420-429), and cerebrovascular disease (ICD codes 430-438), are responsible for more deaths in the United States each year than any other category of disease (5). In 1980, cardiovascular diseases claimed over 960,000 lives, with ischemic heart disease responsible for over 565,000 of these deaths (6). Although the rates of death from cardiovascular diseases have declined gradually over the last decade, coronary atherosclerosis and acute myocardial infarction remain the leading causes of death in the United States.

The role of occupation as a factor in cardiovascular disease is far from clear (7). Most investigators believe that personal risk factors, such as cigarette smoking, blood pressure, diet, personality, and heredity, are more important than environmental factors (8). Specific data are sparse on the role of occupational factors. Nevertheless, some occupational factors are clearly associated with heart diseases, and evidence on other factors is accumulating (9). Because heart diseases are still so prevalent in the United States, identifying and preventing occupational factors that result in even a small increase in the relative risk of cardiovascular disease would involve large numbers of persons. Thus, preventing any occupational contribution to this problem would be an important public health measure.

In 1978, an ad hoc task force was formed by the American Heart Association to review the data regarding the environmental impact on cardiovascular disease (8). Its report, "The Impact of the Environment on Cardiovascular Disease," was published in 1981. The task force identified and reviewed six environmental factors that have potential impact on cardiovascular health: water hardness; trace elements; inhalant occupational exposures; carbon monoxide; noise and radiofrequency; and physical and psychosocial stress. The workplace is a specific source of potential exposure for all but the first.

Metals, Dusts, Trace Elements. The development of congestive heart failure that results from restrictive lung disease (cor pulmonale) has been observed in studies of occupational respiratory diseases, such as chronic beryllium disease and silicosis. Other metals, such as antimony, cobalt, and lead, have been implicated as possible causes of cardiovascular diseases.

Occupational Inhalants and Other Chemical Exposures. These include:

1. Carbon monoxide: Carbon monoxide decreases the oxygen-carrying capacity of hemoglobin and thus reduces the oxygen supply available to heart muscle and other tissues. In persons with preexisting coronary artery disease, occupational exposures to carbon monoxide may precipitate acute cardiovascular events, such as untoward changes in cardiac rhythm. In animal studies, life-threatening arrhythmias, such as ventricular tachycardia and ventricular fibrillation, have been observed in response to exposures to carbon monoxide that produced a carboxyhemoglobin concentration of 9% and above.

   In one study of workers, short-term exposure to carbon monoxide at levels within the current Occupational Safety and Health Administration permissible exposure limit (50 ppm) was associated with decreased exercise tolerance and electrocardiographic evidence of myocardial ischemia. In another study among Finnish foundry workers exposed to carbon monoxide, the overall prevalence of angina pectoris was increased; this was most pronounced among workers who also smoked. Among British steelworkers, investigators found end-of-shift carboxyhemoglobin saturations substantially higher among blast furnace workers than among steelworkers in other jobs. This was observed for both smoking and nonsmoking employees.

2. Carbon disulfide. Carbon disulfide, a widely used solvent, has been shown to increase the risk of cardiovascular disorders, including coronary artery disease and hypertension, in both epidemiologic and experimental studies. It has also been shown to pose a significant risk for coronary death (10). The atherogenic potential of carbon disulfide involves both cerebrovascular and cardiovascular systems.

3. Halogenated hydrocarbons. Acute exposures to many common industrial solvents (e.g., chloroform, trichloroethylene) and fluorocarbon aerosol propellants have precipitated sudden death probably due to cardiac arrhythmias in workers exposed at high levels. Other common aerosols or solvents may be arrhythmogenic at concentrations permitted by current occupational exposure standards. A recent study of pathologists exposed to monochlorodifluoromethane (a fluorocarbon aerosol propellant) in hospitals showed an increased incidence of "palpitations" at levels of exposure far below the recommended standard.

4. Nitroglycerin and nitrates. Workers exposed to nitroglycerin and nitrates during the manufacture of explosives experienced increased risk of cardiac chest pain, myocardial infarction, and sudden death, particularly after a period of time away from exposure. The mechanism is thought to be "rebound vasospasm" as a consequence of withdrawal from exposure. Noise. Tens of millions of workers are exposed to high levels of

sustained and/or intermittent noise in the workplace. A number of studies have demonstrated that single exposures to noise cause transient increases in blood pressure. Chronic exposure to occupational noise has also been associated with sustained increases in blood pressure, particularly in workers with noise-induced hearing loss (11,12). Increases in serum cholesterol and changes in circulating hormones have been observed in humans in association with noise. In studies of animals, abnormalities in platelet aggregation have been documented following exposure to noise.

Psychosocial Stress. Stress has long been thought to adversely affect the cardiovascular system (13). A relationship between psychologic factors and cardiovascular disease is supported by the correlation between "Type A personality" and such disorders. A 1976 assessment suggested that "work-overload," role conflicts, and thwarted career goals were related to evidence of cardiovascular disease. A prospective evaluation of health changes among air traffic controllers, published in 1978, showed an increased prevalence of hypertension among controllers, attributed by the authors to difficulties in coping with working conditions.

An updated analysis of the Framingham heart study in 1980 (14,15), indicated that rates of coronary heart disease were nearly twofold greater among women employed in clerical jobs than among housewives. Significant predictors of the risk of coronary heart disease included a "nonsupportive supervisor" and decreased job mobility. Occupation may also affect the risk of cardiovascular disease in a spouse. Men whose wives worked in white collar jobs were observed to experience heart disease at a rate three times greater than men whose wives worked in clerical or blue collar jobs or were housewives. Similarly, men appeared to have a higher risk of cardiovascular disease if they had well-educated, working wives who reported nonsupportive supervisors or few opportunities for job promotion. These and similar results suggest that adjustments to the conflicting demands of job and family may be important factors in the risk of cardiovascular disease.

Recent evaluations of data from a large random sample of the Swedish working male population (16), and from other surveys, also suggest that certain working conditions, such as limited autonomy and heavy workloads, are associated with clinical indicators of coronary heart disease.

Epidemiologic studies are clearly needed to define the significance of these and other occupational stress factors in the etiology of cardiovascular diseases. Such physical stresses as noise, vibration, and heat also merit investigation for possible interaction with the psychologic risk factors of cardiovascular disease. Reported by Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Because cardiovascular diseases are so prevalent, they clearly affect large numbers of workers in the United States. A proportion of these diseases are caused or aggravated by risk factors in the work environment. NIOSH is currently collecting epidemiologic data to properly evaluate the role of the workplace in these diseases.

Since some occupational exposures clearly contribute to the morbidity and mortality attributable to cardiovascular diseases, further epidemiologic research is essential to define the extent of their occupational role and to define etiologic mechanisms. In addition, since cardiovascular diseases cause so much mortality in the United States, preventing even a small increase in relative risk due to occupational exposures would have major consequences to the public health. That mortality from cardiovascular disease has declined markedly in recent years indicates that these diseases are preventable.

The workplace is an important focus for efforts to prevent cardiovascular disease because: (1) it is the source of some preventable environmental exposures and psychological stresses that adversely affect cardiovascular health; (2) it offers unique opportunities for health promotion activities that encourage workers to improve their personal health behaviors (e.g. smoking cessation, appropriate exercise, and sound nutrition) and; (3) it provides an advantageous setting for delivering preventive services such as screening for hypertension.

References*

1. CDC. Leading work-related diseases and injuries-United States. MMWR 1983;32:24-6,32.

2. CDC. Leading work-related diseases and injuries-United States. MMWR 1983;32:189-91.

3. CDC. Leading work-related diseases and injuries-United States. MMWR 1983;33:125-8.

4. CDC. Leading work-related diseases and injuries-United States. MMWR 1984;33:213-5.

5. Office on Smoking and Health. The health consequences of smoking. Cardiovascular disease: a report of the Surgeon General. Rockville, Maryland: Public Health Service, U.S. Department of Health and Human services, 1983.

6. Levy RI, Moscowitz J. Cardiovascular research: decades of progress, a decade of promise. Science 1982;217:121-9.

7. Roseman KD. Cardiovascular disease and environmental exposure. Br J Ind Med 1979;36:85-97.

8. Harlan WR, Sharret AR, Weill H, Turino GM, Berhani NO, Resnekov L. Impact of the environment on cardiovascular disease, report of the American Heart Association Task Force on environment and the cardiovascular system. Circulation 1981;63:243A-6A.

9. Jenkins CD. Psychologic and social precursors of coronary disease. N Engl J Med 1971;284:244-55,307-17.

10. Nurminen M, Mutanen P, Tolonen M, Hernberg S. Quantitated effects of carbon disulfide exposure, elevated blood pressure and aging on coronary mortality. Am J Epidemiol 1982;115:107-18.

11. Talbott E, Helmkamp J, Matthews K, Kuller L, Cottington E, Redmond G. Occupational noise exposure, noise-induced hearing loss, and the epidemiology of high blood pressure. Am J Epidemiol 1985;121:501-14.

12. Fouriaud C, Jacquinet-Salord MC, Degoulet P, et al. Influence of socioprofessional conditions on blood pressure levels and hypertension control. Epidemiologic study of 6,665 subjects in the Paris district. Am J Epidemiol 1984;120:72-86.

13. Jenkins CD. Psychosocial risk factors for coronary heart disease. Acta Med Scand (Suppl) 1982;660:123-36.

14. Haynes SG, Feinleid M, Kannel WB. The relationship of psychosocial factor to coronary heart disease in the Framingham Study. III. Eight-year incidence of coronary heart disease. Am J Epidemiol 1980;111:37-58.

15. Haynes SG, Feinlsib M. Women, work and coronary heart disease: prospective findings from the Framingham heart study. Am J Public Health 1980;70:133-41.

16. Karasek R, Baker D, Marxer F, Ahlbom A, Teorell T. Job decision latitude, job demands, and cardiovascular disease: a prospective study of Swedish men. Am J Public Health 1981;71:694-705.

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• Additional references are available on request from the National Institute for Occupational Safety and Health, CDC.

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