Multiple exposure pathways and health risk assessment of PAHs in Lanzhou city, a semi-arid region in northwest China

In the sparse studies for multiple pathway exposure, attention has predominantly been directed towards developed regions, thereby overlooking the exposure level and health outcome for the inhabitants of the semi-arid regions in northwest China. However, cities within these regions grapple with myriad challenges, encompassing insufficient sanitation infrastructure and outdated heating. In this study, we analyzed the characteristics and sources of polycyclic aromatic hydrocarbons (PAHs) pollution in PM2.5, water, diet, and dust during different periods in Lanzhou, and estimated corresponding carcinogenic health risk through inhalation, ingestion, and dermal absorption. Our observations revealed the concentrations of PAHs in PM2.5, food, soil, and water are 200.11 ng m−3, 8.67 mg kg−1, 3.91 mg kg−1, and 14.5 ng L−1, respectively, indicating that the Lanzhou area was seriously polluted. Lifetime incremental cancer risk (ILCR) showed a heightened cancer risk to men compared to women, to the younger than the elderly, and during heating period as opposed to non-heating period. Notably, the inhalation was the primary route of PAHs exposure and the risk of exposure by inhalation cannot be ignored. The total environmental exposure assessment of PAHs can achieve accurate prevention and control of PAHs environmental exposure according to local conditions and targets.