Some natural products from two soft coals. Their removal, metal-binding and enzyme inhibitory activity.

The chemical constituents of coal have not been fully characterized in relation to the incidence of coal workers' pneumoconiosis (CWP). In this study two soft coals obtained from mines in which workers had high and low incidences of CWP were leached with aqueous base and acid to remove their acidic and basic components. The results suggest that humic substances similar to those found in soil are present in the coal samples. Further, differences in the quantity of material removed ant its metal-binding and enzyme inhibitory activity are related to disease incidence.