The fibrogenicity of some respirable dusts measured in mice.

A method of bio-assay of the fibrogenicity of respirable dust is described. Quartz, coal, and quartz-coal dust mixtures were administered to mice via the tail vein, and liver collagen was estimated chemically. Groups of mice that had received doses of 10, 15, and 20 mg. of these dusts were killed at intervals of 10, 20, and 30 weeks after injection. There was, in general, a linear relation between liver dust and collagen content, and a higher liver collagen the greater the quartz content of injected dust. At 30 weeks after injection there was good differentiation of the collagen response of liver to dust mixtures of different quartz content. These provide standard curves with which liver collagen response to any unknown dust can be compared. The fibrogenicity of two samples of respirable gold-mine dust was less than would be expected from the quartz content. Dust extracted from a region of massive fibrosis in a coal-miner's lung was more fibrogenic than dust from a lung with simple pneumoconiosis.