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Coal mine dust exposure and spirometry in experienced miners.
Am J Respir Crit Care Med 1996 May; 153(5):1560-1566
A study of spirometric changes in experienced and new coal miners was conducted. Data were taken from the various rounds of the National Study of Coal Workers' Pneumoconiosis (NSWCP) to identify male coal miners who had participated in round-1 (R1; 1969 to 1971) or round-2 (R2; 1972 to 1975) and round-4 (R4; 1985 to 1988). Cross/sectional and longitudinal changes in forced vital capacity (FVC) and one second expiratory volume (FEV1) were determined and compared with cumulative coal mine dust exposure and smoking data. A total of 1,915 males met the study criteria. Their mean age during R4 was 49.9 years (yr). A total of 1,372 were first evaluated during R1 of the NSCWP. The remainder first participated during R2. At R4, 37% were current smokers and 43% were former smokers. All were actively mining during R1 or R2; however, only 51% were still mining at R4. The mean cumulative coal dust exposure during R1 or R2 was 38.5mg/m3-years. The mean cumulative coal dust exposure decreased to 0.9mg/m3-year between R1 or R2 and R4. The average annual changes in FVC and FEV1 from R1 or R2 to R4 were -46 and -39 milliliters per yr (ml/yr), respectively. The average change in the FEV1/FVC ratio over this period was 0.10% per yr. Cross/sectional analysis indicated that during R1 or R2, changes of 0.6ml in FVC and -0.5ml in FEV1 were associated with each mg/m3-year of cumulative coal dust exposure, respectively. These changes were not statistically significant. From R1 or R2 to R4 FVC and FEV1 decreased by -0.10 and -0.07ml/yr per mg/m3-year, respectively. Both were statistically significant changes. The changes were more pronounced in current smokers. The decreases in FVC and FEV1 in the cross/sectional analysis were also significantly more pronounced for new miners than experienced miners. In the longitudinal analysis, the coefficients in the regression equation describing the changes in FEV1 and FVC over time as a function of cumulative dust exposure were positive for new miners and negative for experienced miners. The authors conclude that the pattern and magnitude of the dose response relationship of the FVC and FEV1 changes are different for new and experienced coal miners. These differences could reflect differences in cumulative dust exposure between the two groups and the healthy worker effect in the experienced miners.
NIOSH-Author; Coal-dust; Occupational-exposure; Dust-exposure; Pulmonary-function-tests; Epidemiology; Information-systems; Coal-miners; Spirometry; Coal-workers-pneumoconiosis; Statistical-analysis; Dose-response
Issue of Publication
American Journal of Respiratory and Critical Care Medicine
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division