Cancer risk assessment and source apportionment of the gas- and particulate-phase of the polycyclic aromatic hydrocarbons in a metropolitan region in Brazil

A risk assessment and a source apportionment of the particulate- and gas-phase PAHs were conducted in a high vehicular traffic and industrialized region in southeastern Brazil. Higher concentrations of PAHs were found during summer, being likely driven by the contributions of PAHs in the vapor phase caused by fire outbreaks during this period. Isomer ratio diagnostic and Principal Component Analysis (PCA) identified four potential sources in the region, in which the Positive Matrix Factorization (PMF) model confirmed and apportioned as gasoline-related (31.8%), diesel-related (25.1%), biomass burning (23.4%), and mixed sources (19.6%). The overall cancer risk had a tolerable value, with ∑CR = 4.6 × 10−5, being ingestion the major via of exposure (64% of the ∑CR), followed by dermal contact (33% of the ∑CR) and inhalation (3%). Mixed sources contributed up to 45% of the overall cancer risk (∑CR), followed by gasoline-related (up to 35%), diesel-related (up to 15%), and biomass burning (up to 10%). The risk assessment for individual PAH species allowed identifying higher CR associated with BaP, DBA, BbF, BaA, and BkF, species associated with gasoline-related and industrial sources. Higher risks were associated with PM2.5-bound PAHs exposure, mainly via ingestion and dermal contact, highlighting the need for measures of mitigation and control of PM2.5 in the region.