RESPIRATORY DISEASE IN SOUTHERN WEST VIRGINIA COAL MINERS

Epidemiological data on US coal miners' pneumoconiosis, 1960 to 1988

OBJECTIVES

Statistics on prevalence of pneumoconiosis among working underground coal miners based on epidemiologic data collected between 1960 and 1988 are presented. The main intent was to examine the time-related trend in prevalence, particularly after 1969, when substantially lower dust levels were mandated by federal act.

METHODS

Data from studies undertaken between 1960 and 1968 were collected and compared. Information for the period 1969 to 1988 was extracted from a large ongoing national epidemiologic study. Tenure-specific prevalence rates and summary statistics derived from the latter data for four consecutive time intervals within the 19-year period were calculated and compared.

RESULTS

The results indicate a reduction in pneumoconiosis over time. The trend is similar to that seen in a large radiologic surveillance program of underground miners operated concurrently.

CONCLUSIONS

Although such factors as x-ray reader variation, changes in x-ray standards, and worker self-selection for examination may have influenced the findings to some extent, adjusted summary rates reveal a reduction in prevalence concurrent with reductions in coal mine dust levels mandated by federal act in 1969.

The United Mine Workers of American and the recognition of occupational respiratory diseases, 1902-1968

This study examines the early efforts of the United Mine Workers of America to illuminate the problem of occupational respiratory diseases in the coal fields. The union used the hearings of the US Anthracite Coal Strike Commission of 1902-3 to draw public attention to "miners' asthma." In 1915, it began to agitate for the provision of workers' compensation benefits for victims of this disorder. Throughout the 1950s and 1960s, the union's Welfare and Retirement Fund disseminated information on advances in understanding chronic pulmonary diseases of mining. In particular, the miners' fund promoted the British conceptualization of a distinctive coal workers' pneumoconiosis. At the same time, the staff of the union health plan pressed the US Public Health Service and the Pennsylvania Department of Health to investigate the prevalence of occupational respiratory diseases among bituminous miners. Taken together, these endeavors contributed significantly to growing recognition of the severity and extent of this important public health problem and thus helped lay the foundation for the Federal Coal Mine Health and Safety Act of 1969.

Pulmonary function in coal workers with Caplan's syndrome and non-rheumatoid complicated pneumosoniosis

This retrospective study compares the pulmonary function of 24 coal workers with Caplan's syndrome with that of 36 subjects with non-rheumatoid progressive massive fibrosis (PMF). Allowing for differences in radiographical category, age, years worked underground, and smoking, obstruction to air flow as reflected in the one-second forced expiratory volume, the vital capacity, and the ratio of residual volume to total lung capacity, was significantly less in subjects with Caplan's syndrome. No significant differences in transfer factor were found. These findings may be explained by the different pathological features of the two entities. Selection bias does not appear to be responsible for the differences observed between the groups, but studies designed to eliminate this would be desirable.

Lung mechanics and frequency dependence of compliance in coal miners

The mechanical properties of the lungs were studied in two groups of coal miners. The first group consisted of miners with either simple or no pneumoconiosis and was divided into two subgroups (1A and 1B). The former (1A) consisted of 62 miners most of whom had simple pneumoconiosis but a few of whom had clear films. Although their spirometry was normal, all claimed to have respiratory symptoms. The other subgroup (1B) consisted of 25 working miners with definite radiographic evidence of simple pneumoconiosis but normal spirometric findings. The second major group consisted of 25 men with complicated pneumoconiosis. In subjects with simple pneumoconiosis, static compliance was mostly in the normal range, whereas it was often reduced in subjects with the complicated disease. The coefficient of retraction was normal or reduced in most subjects except those with advanced complicated disease, in several of whom it was elevated. So far as simple pneumoconiosis was concerned, abnormalities, when present, reflected "emphysema" rather than fibrosis. In severe complicated pneumoconiosis, changes suggesting fibrosis tended to predominate. In the 25 working miners (subgroup 1B) dynamic compliance was measured at different respiratory rates. 17 of the subjects in this subgroup demonstrated frequency dependence of their compliance, a finding unrelated to bronchitis and suggestive of increased resistance to flow in the smallest airways.