Tracking PFAS in Drinking Water: A Review of Analytical Methods and Worldwide Occurrence Trends in Tap Water and Bottled Water

Abstract

Per-and polyfluoroalkyl substances (PFAS) used in various industrial applications are pollutants of concern for the environment and human health. Drinking water consumption is one key exposure pathway to PFAS, as recently highlighted by multiple studies on their occurrence in tap and bottled water worldwide. However, PFAS quantification at low part-pertrillion (ng/L) or part-per-quadrillion (pg/L) concentrations remains challenging. PFAS presence in blanks and incomplete method recoveries can lead to false positives or negatives; PFAS concentration changes under different storage durations or conditions can also affect accuracy and precision. Here, we review the most recent data related to analytical methods that were used in research articles for the detection and quantification of PFAS from drinking water. Commonly encountered pitfalls are summarized, and analytical performance is appraised including detection limits, recovery, matrix effects, and other quality assurance/quality control endpoints. In addition, we collated available guidelines for health advisory levels of PFAS in tap water. Finally, we compiled concentration data on legacy and emerging PFAS in tap and bottled water.

How Should We Interpret the New Water Quality Regulations for Per- and Polyfluoroalkyl Substances?

“…Different jurisdictions target PFAS combinations differently, using separate thresholds or combining PFOS, PFOA, or other compounds. Apart from EPA's new proposition and regulations from specific U.S. state agencies, most drinking water thresholds for PFAS typically focus on PFOS, PFOA, and sometimes a few other PFAS (e.g., PFBS, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), PFHxS, PFNA) in the range 20−30 000 ng/L, although some values are significantly higher (see compilation in Teymoorian et al 10 ). Similar guidelines are in place in countries like Australia, Italy, Germany, and Canada, but current propositions in most jurisdictions (including the United States, Canada, Europe, and Australia) will soon be updated with new recommendations.…”

“…Regulations in the United States are mostly based on quantifiable risks, which makes it difficult to account for the tremendous range of PFAS compounds for which we have very little toxicological data. Therefore, the U.S. EPA is unlikely to increase the range of PFAS included in its hazard quotient with an individual default threshold of 10 unless there is toxicological evidence that a specific PFAS is less toxic�such as was made for PFBS. There is definitely a tension between the U.S. approach relying mostly on toxicological data for specific target compounds and a precautionary approach trying to encompass ill-defined risks from PFAS compounds, which may nevertheless behave similarly or act as precursors.…”

Ultrastructural Alterations of the Glomerular Filtration Barrier in Fish Experimentally Exposed to Perfluorooctanoic Acid

“…More recently, the U.S. Environmental Protection Agency has issued interim updated drinking water health advisories for PFOA and perfluorooctane sulfonic acid (PFOS) [ 35 ]. In particular, the interim updated health advisories for PFOA are 0.004 ppt, which is 10 −3 of the detection limit of the currently approved analytical method for PFOA, posing significant challenges in developing ultrasensitive analytical methods [ 36 , 37 ]. These stresses underscore the worldwide concern about the effects of PFAS in general and PFOA in particular.…”

Nanomaterial-Based Advanced Oxidation/Reduction Processes for the Degradation of PFAS

“…The two most representative PFAS are the PFCA perfluorooctanoic acid (PFOA) and the PFSA perfluorooctane sulfonate (PFOS), because they were extensively produced and studied [3]. Due to their persistence, bioaccumulation, and toxicity, some of these substances are now listed in the Stockholm Convention as new POPs [4]. Human exposition to these substances occurs mainly through food ingestion and drinking water [3].…”

“…Currently, due to a myriad of applications [1][2][3][4][5][6][7], PFAS are ubiquitous in environmental water, and sustainable remediation strategies must be designed to improve the quality of water and reduce human health risks burdens. However, due to the high chemical strength of the carbon to fluorine bond, PFAS are known to be highly recalcitrant to conventional water treatment processes [2,6,7].…”