Accelerated silicosis in workers exposed to agate dust: 15 cases analysis

Abstract

Objective To assess the prevalence of silicosis in workers exposed to agate dust in a small private agate mill in Guangzhou. Methods The work processes and records of dust measurements were examined. Free SiO2 content from agate samples was measured. Occupational history was obtained and chest X-ray and lung function tests were carried out. The present investigation was prompted. Results The mean total dust concentrations in sawing, carving and polishing work sites were 9. 9, 3. 5 and 3. 0 mg/m3 respectively, exceeding the national maximum allowance concentration (MAC of 1 mg/m3 ) by 8. 9, 2. 5 and 2. 0 folds. The content of free SiO2 was 90 .5 % and 86% of the particles diameter was smaller than 5 .0 μm. The mean age was (29 .8 ± 4 .9) years and the mean duration of exposure was (3 .5 ± 1 .7)years. Fifteen cases (47%) were diagnosed as accelerated silicosis, including 11 cases of stage Ⅰ and 4 cases of stage Ⅱ. All were from the sawing work site and their pulmonary function were reduced. Up to February 2000, three cases of Stage Ⅰ and three cases of stage Ⅱ had developed to be stage Ⅲ, three died from respiratory failure and six were in critical conditions. The factory was closed soon after the investigation started. Conclusion About half of the workers in the agate mill exposed to agate dust had accelerated silicosis. It suggested that strengthening of the occupational hygiene works in small scale enterprises such as agate mill would be in urgent need especially in developing countries.