Evaluation of the exposure to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) through drinking water and human risk assessment

In the present study, two most commonly used Perfluoroalkyl substances (PFASs), namely perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), were determined in 45 tap water samples from the city of Isfahan (Iran) by dispersive liquid-liquid extraction (DLLME) and liquid chromatography-mass spectrophotometry (LC-MS) analysis. Risk assessment was also performed to determine the risk to human health. The mean concentration of PFOA was 38.1 ± 26.4ng/L (min = 5.1 and max = 1056ng/L). The mean concentration of PFOS was 33.7 ± 25.09ng/L (min = 4.3 and max = 99.2ng/L). The combined concentrations of PFOA and PFOS were above the US-EPA advisory levels (70ng/L) in 48.8% of the samples. The distance between the sampling locations and the water treatment plant showed no significant correlation (p > 0.05). The results of the risk assessment showed that all calculated hazard quotients (HQ) and hazard indices (HI) are below 1, indicating that the risk to human health from exposure to PFOA and PFOS via drinking water in the city of Isfahan was not high for adults and children. These results indicate a significant contamination of Isfahan tap water by PFOA and PFOS of unknown origin. Further studies are needed on the Zayande-Roud River water as a supplier of Isfahan tap water and the efficiency of the water treatment plant and the role of the water distribution network in PFASs contamination of tap water.