Wollastonite exposure and lung fibrosis.

Wollastonite is a naturally occurring acicular or fibrous metasilicate used in ceramics and as a substitute for asbestos in some applications. Wollastonite fibers are rather similar in form, length, and diameter to amphibole asbestos fibers but mineralogically they are different. Dust measurements in both the Finnish limestone--wollastonite quarry and in the flotation plant yielded high concentrations of both total dust and respirable fibers in some operational stages. The clinical study comprised a total of 46 men who had been exposed to wollastonite at the quarry for at least 10 years. Three of the fifteen nonsmokers showed chronic bronchitis. Radiographs revealed slight lung fibrosis among fourteen men, and slight bilateral pleural thickening among thirteen men. Their sputum specimens were normal. Spirometry and nitrogen single breath tests indicated the possibility of small airways disease.