Mortality in an extended follow-up of British coal workers

The Pneumoconiosis Field Research (PFR) programme was established in the 1950s, to evaluate effects of coal mining exposures on the health and mortality of British coal workers. Surveys of working miners were carried out at 5-yearly intervals, initially in 24 collieries but later concentrating on 10, collecting detailed work histories and health information for each recruit. Here we report on cause-specific mortality in a cohort of almost 18,000 men from 10 British collieries, followed up for periods up to 47 years, yielding over 516,000 life-years of follow-up. External analyses compared cause-specific death rates in the cohort to those of the population of the regions in which the collieries were situated, using Standardised Mortality Ratios (SMRs). The causes investigated included lung cancer, stomach cancer, non-malignant respiratory disorders and cardiovascular disorders. SMRs showed evidence of an initial healthy worker effect diminishing over time. Several causes, including non-malignant respiratory disease and lung cancer, showed a significant deficit of mortality at the start of the study period with an excess in the latter part of the follow-up period. In these results, effects of working conditions are likely to be confounded with smoking habits. Overall, we believe our results may be generalised to the British coal industry since nationalisation.