Simple pneumoconiosis and exposure to respirable dust: relationships from twenty-five years’ research at ten British coalmines

This paper presents new information from the Pneumoconiosis Field Research (PFR) about relationships between exposure to airborne coalmine dust and risks of developing simple pneumoconiosis. It is based on data collected since 1953 at ten of the 25 collieries selected originally for the project. The main findings are as follows.1. The correlation between coal mine dust exposure and simple pneumoconiosis which was demonstrated 10 years ago isconfirmed unambiguously. The general pattern of the relationships described Is similar to that reported previously.2. Long-term risks were probably underestimated in the earlier work by one or two (percentage) probabilityunits. The error in the predictions is more than counter-balanced by the lower hazard resulting fromthe more stringent dust standard which was introduced in 1977, and from the reduced likely working-life for British miners in the coming years.3. There are very large variations between collieries in medical responses to similar dust exposures. Thereasons for these differences are not yet known.They dwarf the differences between alternative statistical approaches to the data, and they make it difficult to generalise safely from the average results.4. The variations in pneumoconiosis risks between collieries are not explicable in terms of different quartz levels at the collieries. Nor is there any general pattern in the PFR results which might indicate that quartz exposures amounting to less than about 10 per cent of mixed coalmine dust affect the probability of developing simple pneumoconiosis.5. However, there is evidence from the data that a few men may re-act unfavourably over relatively short (10-year) intervals to dust with a high quartz content.