Composition, Sources, and Health Risks of Polycyclic Aromatic Hydrocarbons in Commonly Consumed Fish and Crayfish from Caohai Lake, Southwest China

This study investigated the occurrence, sources, and health risks of 16 polycyclic aromatic hydrocarbons (PAHs) in commonly consumed fish and crayfish from the Caohai Lake, a typical plateau lake in southwest China. Four dominant species (crucian carp, common carp, yellow catfish, and crayfish) were collected and analyzed. The results showed a generally low level of PAH contamination (mean: 26.7 μg/kg wet weight), with bioaccumulation tendency decreasing as the number of PAH rings increased. Crayfish exhibited the highest total concentration of PAHs, whereas yellow catfish accumulated the most carcinogenic PAHs. Positive matrix factorization (PMF) model identified four primary sources-petroleum leakage, coal combustion, traffic emissions, and biomass burning-with petroleum-derived PAHs being the most significant contributor. The assessment of health risk indicated that while the average hazard index (HI) was below 1, approximately 10% of the samples posed a potential non-carcinogenic risk, particularly from crayfish and yellow catfish. The incremental lifetime cancer risk (ILCR) for DahA, BaP, BaA, and BbF all exceeded the negligible risk level of 10^-6 but remained below 10^-4. Notably, the mean total ILCR (TILCR) approached 10^-4, with yellow catfish presenting the highest carcinogenic risk, highlighting concerns of the carcinogenic risk of PAHs. Source-oriented risk assessment revealed that petroleum leakage was the dominant contributor to non-carcinogenic risk (>55%), while traffic emissions contributed most to carcinogenic risk (>57%). To mitigate carcinogenic risk, implementing stormwater diversion systems along the circular lakeside roads is recommended to reduce the input of traffic-derived PAHs.