Health-risk assessment for workers exposed to polycyclic aromatic hydrocarbons (PAHs) in a carbon black manufacturing industry

This study was established to assess workers’ health-risks posed by PAHs exposures via both routes of inhalation and dermal contact. Personal inhalation exposure sampling was conducted on eight wet pelletizing workers and 22 packaging workers, by using a sampling train comprising an IOM personal inhalable aerosol sampler followed by an XAD-2 sorbent tube. Two workers were randomly selected from both exposure groups, and dermal exposures assessed by using soft polypropylene pads attached to the skin for nine different body surface areas for each selected worker. All personal inhalation and dermal samples were analyzed for 21 polycyclic aromatic hydrocarbon (PAH) species, and then converted to benzo[ a]pyrene equivalent (BaP eq) concentrations by using the list of toxic equivalent factors (TEFs) suggested by Nisbet and LaGoy [Regul Toxicol Pharmocol 16 (1992) 290]. The resultant inhalation and dermal BaP eq exposure levels were used to estimate lifetime risks for lung cancer and skin cancer by using the BaP unit risks of 7.0×10 −2 (μg/m 3) −1 and 37.47(mg/kg bodyweight/day) −1, respectively. Results show the personal inhalation BaP eq exposure levels for pelletizing and packaging workers were 622 and 774 ng/m 3, respectively. The corresponding lifetime lung cancer risks estimated for both exposure groups were 4.35×10 −2 and 5.42×10 −2, respectively. For dermal exposures, results show personal dermal BaP eq exposure levels for both exposure groups were 0.664 and 0.847 μg/kg per day, respectively. The corresponding estimated lifetime skin cancer risks were 1.13×10 −3 and 1.56×10 −3, respectively. Although the estimated skin cancer risks were lower than the corresponding lung cancer risks for both exposure groups, however, both were higher than the designated significant risk level (=10 −3) which was defined by the US Supreme Court in 1980. Considering the bioavailability of particle-bound PAHs still remains unknown, the health risks obtained from this study could be overestimated and thus require further investigation.