Estimation of Amphibole Exposure from Asbestos Body and Macrophage Counts in Sputum: a Survey in Vermiculite Miners

Abstract Asbestos bodies and macrophages were counted in sputum from 170 current workers exposed to calcic amphibole fibres, mainly tremolite. The cumulative exposure of each worker was calculated on the basis of work history and all available air measurements taken since 1956. Macrophages were detected in 47% of workers and asbestos bodies in 75%. Concentrations of bodies, which ranged up to 10 000/ml, were related to cumulative exposure and highly dependent on sputum cellularity. Logistic regression analyses showed the concentration of bodies in sputum was as good or a better predictor of radiographic changes as cumulative exposure estimated from environmental measurements.