The aims of this study were to examine the levels of perfluorinated compounds (PFCs) in groundwater around improperly developed municipal and industrial waste disposal sites, including estimating non-cancer risk and cancer risk from ingestion of the groundwater. A total of 27 groundwater samples were collected from two cities in Thailand, Ayutthaya and Chonburi. Seven target compounds were extracted by solid phase extraction (SPE) and analyzed by high-performance liquid chromatography-tandem mass spectrometer (HPLC-MS/MS). The results showed that the total PFCs in groundwater around municipal waste disposal sites (MWDSs) varied from 1.68 to 7.75 ng/L. In groundwater around the industrial waste disposal site (IWDS), total PFCs varied from 2.64 to 42.01 ng/L, which were significantly different from those found in groundwater around the MWDSs at p < 0.01. PFOS and PFOA were ubiquitous in both areas, while perfluorohexane sulfonate (PFHxS) was frequently found in the samples around IWDS. The findings possibly suggest that PFHxS has been introduced for use as an alternative substance for most current C8 and higher due to it having shorter chain length and shorter half-lives. The results for both non-cancer risk and cancer risk in all samples were acceptable.

Per- and polyfluoroalkyl substances have the potential to leach into groundwater, particularly in areas with potential pollution sources, such as landfills. The composition and distribution of per- and polyfluoroalkyl substances, as well as soil characteristics, are particularly useful for identifying the sources of per- and polyfluoroalkyl substances. The objectives of the present study were to characterise per- and polyfluoroalkyl substance levels in groundwater in Thailand, identify their potential sources and highlight their spatial distribution. Groundwater samples were collected in areas hosting municipal and industrial waste disposal sites. Seven Per- and polyfluoroalkyl substances were extracted from the groundwater samples using the solid-phase extraction technique and analysed by high-performance liquid chromatography-tandem mass spectrometry. These samples contain mostly perfluorooctanoic acid and perfluorooctane sulfonate, with the highest concentrations of 34.96 and 25.88 ng L–1, respectively, obtained from industrial waste disposal site areas. The presence of perfluorohexane sulfonate in most samples from industrial waste disposal site areas suggests its usage as a substitute for perfluorooctane sulfonate-based products. In addition to waste disposal, hierarchical cluster analysis reveals that other sources likely influence the presence of per- and polyfluoroalkyl substances in groundwater in Thailand. Livestock farming and ponds near groundwater wells probably impact per- and polyfluoroalkyl substances levels in the associated groundwater. The spatial distribution of per- and polyfluoroalkyl substances shows that in addition to waste disposal sources, soil characteristics and interactions between their negatively charged components and cations in soils significantly influence the contamination of groundwater in the areas studied.

Per- and polyfluoroalkyl (PFAS) have the potential to leach down to the groundwater particularly in areas with potential source pollution such as landfills. The composition patterns of PFAS, distribution and soil characteristics significantly contribute to their source identification. The objectives of this study were: (1) to examine the levels of PFAS in Thailand groundwater, (2) to identify potential sources, and (3) to study the spatial distribution of PFAS. Groundwater samples were collected around municipal waste disposal sites (MWDS) and industrial waste disposal sites (IWDS). Seven PFAS were extracted by solid phase extraction technique and analyzed by high-performance liquid chromatography tandem mass spectrometer. Total PFAS in groundwater around the MWDSs varied from 1.68 to 7.75 ng L− 1. The total PFAS in groundwater around the IWDS varied from 2.64 to 42.01 ng L− 1. PFOA and PFOS were the most dominant compounds around the MWDS and IWDS areas. PFHxS was frequently observed in the groundwater around the IWDSs, suggesting that it has been used as a substitution of PFOS-based compounds due to it having a shorter chain length or resulting from degradation of fluorotelomers. In addition to source identification, the hierarchical cluster analysis showed that other than the waste disposal site, other factors or activities could have been involved. It was found that livestock farming and an abandoned pond very close to the groundwater well could have affected the levels of PFAS in the groundwater. Moreover, spatial distribution showed that besides the impact of waste sources, soil characteristics and interaction between negative charged PFAS and cation in the soil played an important role in the PFAS contamination in groundwater.