A comparative study on application of three methods of occupational health risk assessment for alumina dust exposure workstations

Background Pneumoconiosis is the most serious and common occupational disease in China. Among the industries with serious exposure to dust, abrasives manufacturing industry is featured with a high incidence of pneumoconiosis.

Objective This study is conducted to compare the applicability of three occupational health risk assessment methods, including the UK Control of Substances Hazardous to Health Essentials model (UK COSHH model), the Australian Occupational Health and Safety Risk Assessment model (Australia model), and the Singapore semi-quantitative risk assessment model of occupational exposure to chemical substances (Singapore model, including exposure index method and exposure ratio method), for alumina dust exposure workstations in abrasive manufacturing industry.

Methods Workers exposed to alumina dust in an abrasive manufacturing company were selected as study subjects. The molding, batching, and blending workstations that reported pneumoconiosis cases were designated as key workstations, and the other alumina dust workstations as non-key workstations. Occupational health investigations and occupational hazard detections were carried out in June 2018. UK COSHH model, Australian model, and Singapore model were used to assess the occupational health risks associated with the selected workstations. The differences in dust concentrations and related risk ratios converted from assessment results were compared between key and non-key workstations. Spearman correlation analysis was performed of the risk ratios.

Results There were 23 alumina dust exposure workstations in the selected enterprise. The concentration of alumina dust in the molding workstation of the first workshop production line A exceeded the standard (4.31 mg·m^-3), and the unqualified rate was 4.35%. The average dust concentration of the 12 key workstations was significantly higher than that of the 11 non-key workstations(1.52±1.19) mg·m^-3 vs (0.66±0.51) mg·m^-3, t=2.216, P=0.038. The occupational health risks of the alumina dust workstations were at medium level. The risk ratios of the key workstations derived from the UK COSHH model, Australian model, and Singapore model exposure index method (0.44±0.11, 0.55±0.09, and 0.54±0.03, respectively) were significantly higher than those of the non-key workstations (0.25±0.00, 0.42±0.06, and 0.43±0.04, respectively) (P < 0.05). The Singapore model exposure ratio method did not identify a risk difference between the key and the non-key workstations. There were correlations between the risk ratios of either two models, and the top three correlation coefficients (r_s) were 0.811 (RR_{Singapore model exposure index method} and RR_{Australia model}), 0.790(RR_{Singapore model exposure index method} and RR_{UK COSHH model}), and 0.735 (RR_{Australia model} and RR_{UK COSHH model}).

Conclusion The three occupational health risk assessment models differ in evaluating methods, scopes, judgement basis of hazard rating, judgement basis of exposure rating, users, and intervention measures to reduce risk levels. The UK COSHH model, Australia model, and Singapore model exposure index method are more suitable for the occupational health risk assessment of alumina dust exposure workstations in abrasives manufacturing industry.