An investigation into the cytotoxicity of respirable dusts from British collieries

A series of respirable dusts from British collieries was collected and analysed for mineral content and physical characteristics. Where possible 2 samples of dust were collected from the same site at 8-month intervals. All dusts were tested for their cytotoxic potential using a permanent line of macrophage-like cells (P388D1). In addition, for some dusts, a haemolytic technique was used. With both techniques a positive overall correlation was found between cytotoxicity and the total ash content of the dusts. When the results from collieries producing high- and low-rank coals were considered separately, however, it was found that the ash content of high-rank dusts (r=0.75) showed a much closer correlation with cytotoxicity than low-rank dusts (r=0.40). With the cell test system the ash components, kaolin and mica (r=0.58) and to a lesser extent quartz (r=0.48) showed significant positive correlations with cytotoxicity for high-rank coal dusts but not for low. Using the haemolytic system, however, only the quartz content of the high-rank dusts showed a significant relationship (r=0.69) to levels of haemoglobin release. Both the results of mineralogical analysis of dust samples and cytotoxicity tests showed that the mineral content and cytotoxic potential of dusts collected from the same colliery, and even from the same underground site, at different times, varied considerably. A poor correlation was found between cytotoxicity and various measurements of pneumoconiosis risk but this may well be partly due to this great variation of dust composition with time. In general, the overall results of this study were in good agreement with those of previous work on coal dust toxicity in that both the rank and composition of colliery dusts were found to be of importance, whereas the role of quartz remained enigmatic.