ABSTRACT
Background The mining of non-coal underground mines may come into contact with various types of dust, such as lead, zinc, copper, and non-metallic minerals. Dust of various kinds commonly exists in all aspects of mining and selection, and is one of the main occupational hazard groups in non-coal underground mines. Objective To compare the application of two risk assessment methods in the occupational health risk assessment of productive dust in non-coal underground mines, and to provide a reference for the selection of dust hazard health risk assessment methods and the management of dust hazards in non-coal mines. Methods A field investigation of the dust hazards of three typical non-coal underground mining enterprises (lead-zinc mines, copper mines, and fluorite mines) was carried out, and the comprehensive index method and the occupational health risk assessment method from the International Council on Mining and Metals (ICMM) were used to perform risk assessments. The comprehensiveindex method considers the following factors: dust monitoring data, the aerodynamic diameter of dust, hazard control measures, occupational health management, daily usage, and daily exposure time to determine exposure levels. The ICMM method determines the risk level based on the consequences caused by dust, exposure probability, exposure time, and uncertainty coefficient. Kendall consistency test was used to compare agreement between the results generated by the two methods. Results The results generated by the comprehensive index method were as follows: level 3 (medium risk) or level 4 (high risk) for silica dust or lead dust; level 1 (negligible risk) or level 2 (low risk) for other dust (dust with free SiO2 content<10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The risk levels graded by the ICMM method were as follows: level 4 (very high risk) and level 3 (high risk) for exposure to silica dust and lead dust, respectively, and level 1 (tolerable risk) or level 2 (potential risk) for exposure to other dust (dust with free SiO2 content <10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The consistency level between the results graded by the two methods was very high (Kendall W coefficient=0.974, P < 0.05). Conclusion For the occupational health risk assessment of productive dust in non-coal underground mines, the consistency level of risk assessment results between the ICMM method and the comprehensive index method is very high. The ICMM method is more convenient to operate and should be preferred in assessing health risks of dust hazard in non-coal underground mines.
ABSTRACT
Background The complex and diverse occupational disease hazards in automobile manufacturing industry pose high occupational health risks to workers. Objective To explore the methods that can accurately reflect the workplace health risk grade of automobile manufacturing enterprises, and to guide enterprises to practice risk classification management. Methods Comprehensive index method, International Commission on Mining and Metals occupational health risk assessment method (ICMM method), and risk index method were used toassess health risks of occupational disease hazards in major workstations such as welding, polishing, and painting in three automobile manufacturing enterprises in Hunan Province. Kappa consistency test was used to test the grading results of the three assessment methods. The re-examine results and detection rate of contraindications of occupational health examinations in the past three years were used to verify the assessment results. Results The results of comprehensive index method showed that the hazards of each selected workstation in enterprises A and B were evaluated as grade 2-3, among which NO2 in enterprise A was grade 3, and welding fume, NO2, and formaldehyde in enterprise B were all grade 3. The hazards of each selected workstation in enterprise C were grade 3-4, among which NO2 and benzene in were grade 4, and welding fume, manganese and its compounds, grinding wheel dust, and xylene were grade 3. The hazards evaluated by ICMM quantitative method were grade 2 and grade 5, among which manganese and its compounds in enterprise A and welding fume, grinding wheel dust, and benzene series in enterprise C were graded as grade 5. The hazards evaluated by risk index method were grade 1-4, among which manganese and its compounds in enterprises A and B were grade 3, and manganese and its compounds and benzene in enterprise C were grade 4. The Kappa value between comprehensive index method and ICMM method was 0.084 (P>0.05), that between comprehensive index method and risk index method was −0.046 (P>0.05), and that between ICMM method and risk index method was 0.014 (P>0.05), indicating poor consistency. By comparing the results of occupational health surveillance with the results of occupational health risk assessment, one worker was found to have occupational contraindication of manganese exposure and 1 worker was found to have excessive manganese in hair in enterprise A. However, the comprehensive index method graded low risk for manganese and its compounds in enterprise A and the result is conservative. The key workstations identified by ICMM method were consistent with the occupational health examination results, but the assessment grades were all extremely high risk, and the results were too strict. One worker was found to be contraindicated to welding fumes, and 2 polishers were found to have severe mixed pulmonary ventilation dysfunction in enterprise C. Mild and moderate pulmonary ventilation dysfunction was found to be common in welding and polishing workstations in each enterprise. The assessment results of welding fumes and grinding wheel dust by the risk index method were negligible risks, which were inconsistent with the occupational health examination results. Conclusion The comprehensive index method, ICMM method, and risk index method can basically identify workstations with serious occupational hazards, but they have certain limitations and applicability. In general, the evaluation results of the comprehensive index method were generates more consistent with the results with occupational health surveillance than the other two methods, is more comprehensive and objective in consideration, and is more suitable for health risk assessment of automobile manufacturing enterprises.