Health risk assessment on polycyclic aromatic hydrocarbons (PAHs) in high-rank, high-organic sulfur coals

In this study, the concentrations of 16 US Environmental Protection Agency (USEPA)-priority polycyclic aromatic hydrocarbons (PAHs) in 29 high-rank, high-organic sulfur coal samples were determined using gas chromatography-mass spectrometry. Additionally, the total sulfur, sulfur forms content, and the vitrinite reflectance were also measured. An Incremental Lifetime Cancer Risk (ILCR) standard model was employed to evaluate potential carcinogenic risk induced by PAHs. The results indicated that the samples can be classified as high-rank, high-organic sulfur coals. Nine individual PAHs out of the 16 USEPA-priority PAHs can be detected, and their total concentrations ranged from 3492.76 to 88,342.61 ng/g, with an average of 13,645.40 ng/g. The detected PAHs were dominated by low-molecular weight PAHs. The results of health risk assessment indicated that all the samples exhibited extremely high carcinogenic risks induced by the PAHs, with total ILCR ranges of 1.16 × 10 −3 –5.47 × 10 −2 and 6.03 × 10 −4 –2.84 × 10 −2 for adults and children respectively, which far exceeded the USEPA-recommended severe risk threshold (10 −4 ). For all demographic groups (gender/age), ingestion and dermal contact were identified as the main exposure pathways of PAHs inducing the carcinogenic risks, while the risk from inhalation pathway was negligible. The results also illustrated that high contents of organic sulfur in the coals can result in an elevation of indeno[1,2,3- c , d ]pyrene concentration with a high toxic equivalency factor, thereby exacerbating the ultimate carcinogenic risks.