Occupational health risk assessment of n-hexane based on four risk assessment models

Background N-hexane has been a widely used solvent in industrial production, but it is volatile at room temperature and can be accumulated in the body, and its prolonged occupational exposure may lead to serious chronic diseases in workers.

Objective To use four risk assessment models to evaluate the health risk levels of n-hexane-exposed workers, discuss the applicability of the four models in the health risk assessment of n-hexane exposure, and make an important supplement to the health risk assessment of n-hexane in China.

Methods In 2022, a total of 167 jobs (1724 workers) exposed to n-hexane in 85 manufacturing enterprises in Jiangsu Province were selected, and a cross-sectional study was conducted and included questionnaire surveys and evaluation of on-site air n-hexane of each job. Subsequently, the China’s classification standards of occupational hazards at workplaces (China model), U.S. Environmental Protection Agency (EPA) model, Singapore semi-quantitative risk assessment model (Singapore model), and the International Council on Mining and Metals (ICMM) model were applied to the quantitative, semi-quantitative, and qualitative assessments of the occupational health risk level of n-hexane-exposed workers.

Results All job’s 8-h time-weighted average concentrations (C_TWA) of n-hexane were within the national occupational exposure limits (OELs). The results of the China model graded all jobs as relatively harmless. The Singapore model graded all jobs as low risk, except that two monitoring sites of adhesive jobs were assessed as medium risk. The ICMM quantitative model evaluated all jobs as intolerable for n-hexane airborne exposure, while the matrix method evaluated all jobs as low risk. The U.S. EPA model identified five sites involving painting, printing, and adhesive jobs as high risk and the other jobs as low risk.

Conclusion Inconsistent grading results are observed by using the four models for the occupational health risk assessment of n-hexane exposure, that is, harmless for all jobs by China model, while medium and high risks by Singapore model and U.S. EPA model. Therefore, we recommend to combine the Singapore model and the U.S. EPA model with the China model to assess the occupational risk of n-hexane-exposed workers by considering actual concentrations of exposure.