In this study, the authors investigated prevalence characteristics and influence factors of pneumoconiosis of workers exposed to dusts in an iron mine. In addition, they provided a number of preventive measures for pneumoconiosis. The subjects of cohort study where all workers exposed to dusts for at least one year registered in an iron mine during 1960 to 1974, and followed up to the end in 2003. The cases with pneumoconiosis were diagnosed by the local diagnosis group of pneumoconiosis, according to the national diagnostic criteria of pneumoconiosis. The risk factors were analysed with Cox risk model. A total of 3,647 miners were included in the cohort study and were followed up by 132,574.4 person years. There were 316 cases with pneumoconiosis, and the incidence of pneumoconiosis for a year was 0.24. There were 274 cases (86.7%) with pneumoconiosis in workers exposed to dusts before 1960, the incidence of pneumoconiosis for a year was 0.40%, which was significantly higher than that (0.07%) of workers exposed to dusts after 1960. The average latency of pneumoconiosis was 26.0(7.3 years. The average durations of upgrade from stage 0+ to I, I to II and II to III were 5.3(3.2, 6.6(5.2 and 11.3(5.0 years, respectively. However, 164 cases with pneumoconiosis were diagnosed after ceasing exposure to dusts for mean 8.3 years. The findings showed that the risk of pneumoconiosis in iron miners increased with exposure doses, and there was an obvious dose-effect relationship. The average cumulative exposure dose of cases with pneumoconiosis was 173.7(91.6 mg/m3áy, which was significantly higher than that (112.1(64.8 mg/m3áy) of workers without pneumoconiosis. Furthermore, tuberculosis (HR)5.9, P<0.001) and smoking (HR)1.7, P<0.01) were the main risk factors. The authors concluded that there was an obvious dose-effect relationship between the cumulative exposure dose and pneumoconiosis incidence. Tuberculosis and smoking were the main risk factors influencing the pneumoconiosis incidence.
Authors: Guan, Hongyu; Zhang, Hao; Su, Liangping; Liu, Yuewei; Weng, Shaofan; Chen, Weihong ;Full Source: Zhonghua Laodong Weisheng Zhiyebing Zazhi 2012, 30(1), 36-40 (Chinese) ;