Biopersistence of the mineral matter of coal mine dusts in silicotic human lungs: is there a preferential release of iron?

Toxic potency of quartz-containing dusts, including coal mine dusts, is usually inhibited by protective clay mineral layers on the surface of quartz particles. This investigation of 11 dusts recovered from lungs of coal miners with different silicosis grade shows that such layers persist during long-term contact with human lung tissues. On the other hand, the results suggest that an apparently preferential release of iron occurred in lungs with massive fibrosis. These preliminary results support the hypothesis of an iron-related harmfulness of coal mine dusts.