Contrasting geographical distribution of mortality from pneumoconiosis and chronic bronchitis and emphysema in British coal miners.

To explore whether the characteristics of coal mine dust that predispose to chronic airways obstruction are the same as those associated with pneumoconiosis, mortality from the two disease was compared in coal miners in 22 counties of England and Wales during 1979-80 and 1982-90. The proportional mortality ratios (PMRs) for coal workers' pneumoconiosis varied from 135 (95% confidence interval (95% CI) 16-488) in Leicestershire to 3825 (95% CI 1538-7881) in South Glamorgan. The PMRs for chronic bronchitis and emphysema were consistently higher than those in other occupations, but showed much less geographical variation and did not correlate geographically with those for pneumoconiosis. These findings indicate that the pathogenetic mechanisms by which coal mine dust causes chronic bronchitis and emphysema depend on different features of the dust from those producing pneumoconiosis. Also, they suggest that current social security regulations in Britain, which require evidence of pneumoconiosis as a condition of compensation for chronic bronchitis and emphysema in coal miners, may discriminate unfairly against claimants from some regions.