Per- and polyfluoralkylated substances (PFAS) and other emerging contaminants in groundwater from central urban areas of São Paulo city, Brazil.

The increasing demand for consumer products has led to the continuous introduction of novel substances into the environment. This contributes to contamination of environmental compartments and poses potential risks to human health. Many of these substances are classified as emerging contaminants and are detected at trace levels in various matrices, including groundwater. This study investigates the presence of emerging contaminants in shallow groundwater from a nonindustrial urban area potentially impacted by domestic wastewater, with an emphasis on per- and polyfluoroalkyl substances (PFAS). Twenty groundwater samples were collected in São Paulo city, Brazil, from older neighborhoods suspected of sewage collection system leakage, covering an entire hydrological cycle, that is, both dry and wet seasons. Samples were analyzed using liquid chromatography coupled with mass spectrometry (LC-MS/MS). PFAS were detected in concentrations ranging from 4.8 to 45.7 ng/L, with PFOS and PFOA being the most prevalent. Additionally, pesticides (1.1-736 ng/L), hormones (< LOQ-8.0 ng/L), pharmaceuticals (2.9-255 ng/L), and industrial compounds (14.1-314 ng/L) were also quantified in the samples. Although these concentrations are considered background levels associated with diffuse sources, the findings highlight the need for more comprehensive studies to assess the occurrence, sources, and potential health impacts of emerging contaminants in groundwater systems.