Risk assessment of PAH exposure involving metal working fluids in fastener manufacturing industries

Thirty-four air samples from different working areas of three fastener factories were collected to assess the gaseous/particulate-phase polycyclic aromatic hydrocarbon (PAH) levels as well as to assess the total-PAH level associated to health risks in fastener manufacturing workers. The higher total-PAH level were found in heat treatment area (1221 ng m⁻³), threading area (920 ng m⁻³), forming area (897 ng m⁻³), packing area (878 ng m⁻³), and acid-cleaning area (850 ng m⁻³); in addition, higher BaPeq levels were found in packing area (216 ng m⁻³), threading area (103 ng m⁻³), heat treatment area (99.3 ng m⁻³), forming area (91.1 ng m⁻³), and surface treatment area (87.1 ng m⁻³). Because metal working fluids are widely used in fastener manufacturing factories, PAH emissions in the gas phase (over 80%) were predominant in these working areas except for in packing area. Although the average total BaPeq exposure levels were lower than the permissible exposure limit set by the Occupational Safety and Health Administration (OSHA, 8 h time-weighted average: 0.2 mg m⁻³), the lung cancer risks associated with the above mentioned PAH exposures were 4.36 × 10⁻⁴–1.14 × 10⁻³, and the gaseous-phase PAH exposure risk was much higher than that from particulate-phase exposure in workers exposed to oil mists in a fastener manufacturing factory. The results of this study suggest that the occupational hazards of PAHs cannot be neglected for workers in the fastener manufacturing industry; occupational hazard prevention must focus on gaseous- as well as particulate-phase PAH exposure.