Residues of polycyclic aromatic hydrocarbons in the soils of Benevento Province, southern Italy: Implications for sources and environmental risks

Although marginalized Mediterranean regions are widely characterized by depopulation, economic decline, and reduced anthropogenic activity, the polycyclic aromatic hydrocarbon (PAH) pollution characteristics and health risks in such areas remain insufficiently studied. Taking Benevento Province in southern Italy as a case study, we collected 64 surface soil samples to integrate multifractal analysis with positive matrix factorization modeling for pollution hotspot identification and source apportionment, while introducing non-priority dibenzopyrenes (DBPs) to evaluate systematic bias in conventional carcinogenic risk assessment. Results showed that 16 USEPA priority PAHs were detectable in 96.7% of sampling sites (9.50–1188 ng/g, mean: 55.0 ng/g), with overall low but spatially heterogeneous pollution (coefficient of variation: 54.3% for dibenz( a,h )anthracene and up to 491% for phenanthrene). Pollution hotspots were concentrated near eastern landfills, highlighting dominant local point-source effects. PAH concentrations correlated with total organic carbon and population density, while the positive correlation between sand content and PAH concentrations was attributable to confounding effects of population density. Source apportionment identified biomass/coal combustion (42.2%), vehicle emissions (40.2%), and petroleum volatilization/leakage (17.6%) as primary sources. Air-soil exchange analysis revealed the net volatilization of benzo( a )pyrene and naphthalene, indicating that the soil acts as both a sink and a secondary emission source. Non-priority PAHs, particularly DBPs, accounted for 68.1%–99.1% of the total carcinogenic risk, highlighting systematic underestimation of health risks in marginalized areas. Monte Carlo simulations indicated acceptable incremental lifetime cancer risk ( ILCR ) levels (10−6–10−4) across age groups, with food ingestion as the dominant exposure pathway. Customized PAH risk assessment frameworks tailored to marginalized regions are recommended.