[The study of the characteristics and influencing factors of pneumoconiosis among workers exposed to dusts in an iron mine].
OBJECTIVE
To analyze the prevalence characteristics and influence factors of pneumoconiosis of workers exposed to dusts in an iron mine, to provide the base of preventive measures for pneumoconiosis of iron mine.


METHODS
The subjects of cohort study were 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 analyzed with Cox risk model.


RESULTS
A total of 3647 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 per thousand. 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 per thousand, which was significantly higher than that (0.07 per thousand) 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 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/m3 x y, which was significantly higher than that (112.1 +/- 64.8 mg/m3 x y) of workers without pneumoconiosis. Also the tuberculosis (HR = 5.9, P < 0.001) and smoking (HR = 1.7, P < 0.01) were the main risk factors.


CONCLUSIONS
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.
MOE Key Lab of Environmental and Health, School of Public Health, Tongli Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
Hong-Yu
HY
Guan
Hao
H
Zhang
Liang-Ping
LP
Su
Yue-Wei
YW
Liu
Shao-Fan
SF
Weng
Wei-Hong
WH
Chen
D000328:Adult; D000368:Aged; D000395:Air Pollutants, Occupational / Q000032:analysis; D015331:Cohort Studies; D004391:Dust / Q000032:analysis; D005260:Female; D006801:Humans; D015994:Incidence; D007501:Iron; D008297:Male; D008875:Middle Aged; D008906:Mining; D016273:Occupational Exposure; D011009:Pneumoconiosis / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors
D000395:Air Pollutants, Occupational; D004391:Dust; D007501:Iron