Compared in vitro and in vivo toxicity of coalmine dusts. Relationship with mineralogical composition

In order to explain why differences in frequency of pneumoconiosis are observed between European coalmines, 23 samples of respirable dust were collected from selected collieries in Belgium, West Germany, France and the United Kingdom. Their physical and mineralogical characteristics were determined and their cell and tissue toxicity measured (the work being funded in part by the European Coal and Steel Community). The relationship between these two sets of data was researched and the results compared with the available epidemiological data. Samples of a high mineral content show the highest concentration of fine particles. The main mineral components are, in order of decreasing concentration, mica, kaolinite and quartz, the relative proportion of the three being variable. The dusts were not particularly toxic, regardless of whether testing was in vitro or in vivo. The most representative tests were selected and the 23 samples distributed among three classes: marked, moderate and low toxicity. Toxicity is well correlated with mineralogical composition. In vivo tests show that toxicity increases not only with mineralogical content but also with quartz content. The protective effect of mica is confirmed. The epidemiological data correlate poorly with in vitro tests, but better with in vivo tests.