Dose-response relationship analysis between cumulative coal dust exposure and pneumoconiosis risk

Abstract

Objective: To explore the dose-response relationship between the cumulative coal dust exposure and the cumulative prevalence rate of pneumoconiosis among the coal miners, and to provide a basis for the revision of exposure concentration limits standards of the respirable coal dust and the total dust. Methods: A retrospective cohort study was conducted to study the coal miners in 11 state-owned coal mines from January to August 2013. 21000 coal miners in the 9 coal mines were adopted in the furthre study after the bias treatment.The occupational health records of coal miners from the date of coal production to the end of 2012 in each coal mine were collected. Based on the cumulative dust exposure group of the respirable coal dust and that of the total dust, both the miner's cumulative prevalence rate of pneumoconiosis were calculated by the life table method respectively. The dose-response relationship between the cumulative coal dust exposure and pneumoconiosis risk was established (subject to logistic regression model) . Assuming the cumulative prevalence rate is not higher than 1% after 30 or 25 years of exposure to coal dust and the safety factor is 1.2, the exposure concentration limits of the respirable coal dust and the total dust were calculated by the logistic regression equations with one-sided interval statistical control. Results: There were 3224 pneumoconiosis patients (15.35%) altogether. The dose-response relationship between the cumulative respirable coal dust exposure and the cumulative prevalence rate of pneumoconiosis is a logistic regression equation logistic(r)=5.649lgDr-16.573 (R(2)=0.925) , and the legistic regression equation for the total dust, is logistic(t)=5.712lgDt-18.767 (R(2)=0.897) . When the prevalence rate of pneumoconiosis after 30 years of exposure to coal dust is not higher than 1%, the exposure concentration limits of the respirable coal dust and that of total dust contact are 2.2 mg/m(3) and 4.8 mg/m(3), which are similar to those of national occupational health standards of China (2.5 mg/m(3) and 4 mg/m(3)) . When the prevalence rate of pneumoconiosis after 25 years of exposure to coal dust is not higher than 1%, the exposure concentration limits of the respirable coal dust is 2.7 mg/m(3). Conclusion: It is recommended to strictly implement the current national occupational health standard and abolish the relevant safety production industry standard.