Per- and polyfluoroalkyl substances in the atmospheric total suspended particles in Karachi, Pakistan: Profiles, potential sources, and daily intake estimates
By Huiju Lin, Sachi Taniyasu, Nobuyoshi Yamashita, Muhammad Kamran Khan, Saiyada Shadiah Masood, Sumayya Saied, and Haider Abbas Khwaja
October 12, 2021
Per- and polyfluoroalkyl substances (PFAS) have received continuous attention; however, there is limited understanding of their sources in the atmosphere and related human exposure risks. This study measured PFAS in the atmospheric collected from Karachi, Pakistan, during the winter. Among the quantified PFAS, perfluorobutanoic acid (PFBA) showed the highest average concentration (3.11 ± 2.64 pg/m), accounting for 32% of the total PFAS. Wind speed was positively correlated with perfluorohexanoic acid (PFHxA) and N-ethyl perfluorooctanesulfonamide (N-EtFOSA), while relative humidity was negatively correlated with perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Weighted potential source contribution function (WPSCF) and concentration weighted trajectory (WCWT) analyses suggested that northwestern Pakistan and western Afghanistan areas were highly associated with the long-range atmospheric transport of PFAS. We also calculated the estimated daily intake of PFAS, which were in the range of 0.072-3.98 and 0.006-0.325 pg/kg bw/d for children and adults, respectively. The calculated hazard quotient (HQ) of PFOS and PFOA was significantly lower than 1, indicating less or unlikely to cause non-carcinogenic effect via inhalation exposure. Overall, this study contributes to the understanding of geographic origins and human inhalation risks of airborne PFAS on a regional scale.