An investigation of dust composition and other factors at collieries where the pneumoconiosis progression index appears to be anomalous in relation to dust concentration. Final report on CEC Contract 6253-32/8/066

Routine dust and radiological statistics were examined for 274 British collieries for the period 1970-75 and were used to identify collieries where regression of simple pneumoconiosis appeared unusually high or low in relation to their dust levels. Eight of these collieries were selected for further study.For each selected colliery, an assessment was made of pre-1970 dust conditions, the pattern of dust distribution in the coalface area and the time spent by faceworkers at other collieries. Composition, size and toxicity characteristics of the dusts were also measured, as were oxides of nitrogen levels.The apparently anomalous dust/disease patterns at six collieries are at least partly explicable in terms of manpower movements into the “”anomalous”” collieries from elsewhere and invalid assessments of dust concentrations in earlier years. Similar considerations failed to explain the marked increase in progression of simple pneumoconiosis observed in 1972 at the two other collieries selected for investigation. However, as the apparent anomalies had been resolved by the time of later radiological surveys at these two collieries it is possible that the apparent discrepancies may be associated with temporal variations in radiological techniques.It appears that despite as yet unexplained colliery-associated variations in response to given dust exposures the average results from the Pneumoconiosis Field Research provide a reliable guide to dust-dose-specific risks of simple pneumoconiosis. “”