Accelerated silicosis in workers exposed to agate dust in Guangzhou, China.

BACKGROUND: An investigation of a small private agate mill was prompted by an agate worker who presented with silicosis in Guangzhou, China, in December 1998. METHODS: The work processes and records of dust measurements of the mill were examined. The mean total dust concentrations ranged from 3.0 to 9.9 mg/m3; 86-88% of the particles' diameter was smaller than 5.0 microm. Free SiO2 content from agate samples was measured. Occupational history was obtained and X-ray chest and lung function was carried out. RESULTS: Free SiO2 content of the agate was 90.5%. Thirty-two men involved in processing agate stone were examined. The mean ( +/- SD) age was 29.8 ( +/- 4.9) years and the mean (+/- SD) duration of exposure was 3.5 (+/- 1.7) years. Fifteen cases (47%) were diagnosed as accelerated silicosis. Up to September 1999, three had died from respiratory failure and five were in critical condition. CONCLUSIONS: Silicosis is an important problem in primitive work environments.