HISTORICAL TOTAL AND RESPIRABLE SILICA DUST EXPOSURE LEVELS IN MINES AND POTTERY FACTORIES IN CHINA

Historical exposure estimates of total dust and respirable silica were made in a recent nested case-referent study of lung cancer among mine and pottery workers in China. Exposure to total dust and respirable s ilica was assessed in 20 mines and 9 pottery factories. The average to tal dust concentration was 7.26 mg . m(-3) with a range from 17.68 mg . m(-3) in the 1950s to 3.85 mg . m(-3) in the 1980s, while the averag e respirable silica dust was 1.22 mg . m(-3), with a range from 3.89 m g . m(-3) in the 1950s to 0.43 mg . m(-3) in the 1980s. The highest re spirable silica dust occurred in the underground mining operations (1. 43 mg . m(-3)), particularly for manual drillers (9.03 mg . m(-3)). Am ong all facility types, tungsten mines had the highest respirable sili ca dust exposure (1.75 mg . m(-3)), while the lowest exposure occurred in copper-iron mines (0.32 mg . m(-3)).