Occurrence, Source Apportionment and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Rainwater from Niger Delta Oil-Producing Communities: Policy and Management Implications

Oil extraction activities, particularly gas flaring and artisanal refining, have contributed to the contamination of rainwater in the Niger Delta, potentially increasing human exposure to toxic chemicals. Given the limited information on the occurrence, distribution, and sources of PAHs in rainwater across multiple emission pathways, this study investigated sixteen USEPA priority PAHs in rainwater samples from seven oil-producing communities in Ogbia Local Government Area (LGA), Bayelsa State, Nigeria. Eleven PAH congeners were detected, with total PAH concentrations ranging from 0.22 to 1.27 µg/L and an overall mean of 0.519 ± 0.360 µg/L. Mean environmental concentrations (MEC) ranged from 0.0300 µg/L for acenaphthene to 0.3860 µg/L for phenanthrene, while RWIM1 was identified as a spatial hotspot. Phenanthrene exceeded the USEPA chronic water quality criterion (0.2 µg/L) and its ERL (0.240 µg/L), while acenaphthene exceeded its ERL (0.016 µg/L). Diagnostic molecular ratios indicated mixed petrogenic and pyrogenic inputs, while PCA identified petroleum- and combustion-related influences, with the first two components explaining 88.13% of the total variance. Carcinogenic risk assessment showed elevated cumulative Risk Index (RI) values, with the highest value of 7.47 × 10⁻¹ observed in children through dermal exposure, while Hazard Index values remained below the USEPA threshold. The findings highlight rainwater as an important pathway for PAH exposure and support stronger enforcement of emission standards for gas flaring and artisanal refining, alongside household-level measures to reduce exposure from untreated rainwater, particularly among children.