OBJECTIVETo explore the minimum observed adverse effect level(LOAEL) and intensity of pathogenesis of tin mine dust.

METHODSA cohort study design with retrospective assessment of exposure was used. Selected 4,471 male tin miners who were exposed to tin at least one year during 1960 to 1974 and were compared with 4,797 pottery dust exposed workers in the same way designed. Statistical analysis system SAS, PROC LIFETEST were used to perform the non-parameter calculation by Life Table method.

RESULTSTin mine cohort subjects were followed up to December 31, 1994. The percentage of miners who developed silicosis was 21.7% (971/4,471). 81% of the patients had been exposed to dust before 1958. The cumulative total dust exposure(CTD) was significantly correlated with silicosis risk. The risk of silicosis was 0.012 when CTD was less than 50 mg/m-3.year-1. The risk of silicosis was increased to 0.971 when CTD was beyond 400 mg.m-3.year-1. However, the risk of silicosis was only 0.369 for dust exposed workers in pottery factories when CTD was beyond 400 mg.m-3.year-1.

CONCLUSIONThere was significant relationship between cumulative dust exposure and the incidence of silicosis in tin exposed workers. And silicosis induced by tin mine dust is more serious than the pottery dust.

Cohort Studies ; Dust ; Humans ; Mining ; Occupational Exposure ; adverse effects ; Silicosis ; etiology ; Tin