
==== Front
Eco Environ Health
Eco Environ Health
Eco-Environment & Health
2772-9850
Elsevier

S2772-9850(24)00049-8
10.1016/j.eehl.2024.05.008
Review
Emergency of per- and polyfluoroalkyl substances in drinking water: Status, regulation, and mitigation strategies in developing countries
Adewuyi Adewale walexy62@yahoo.com
ab⁎
Li Qilin qilin.li@rice.edu
bcde⁎
a Department of Chemical Sciences, Faculty of Natural Sciences, Redeemer's University, Ede, Osun State, Nigeria
b Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA
c NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Rice University, Houston, TX 77005, USA
d Department of Materials Science and Nano Engineering, Rice University, Houston, TX 77005, USA
e Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA
⁎ Corresponding authors. walexy62@yahoo.comqilin.li@rice.edu
26 6 2024
9 2024
26 6 2024
3 3 355368
4 3 2024
24 4 2024
21 5 2024
© 2024 The Author(s)
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
The detection of per- and polyfluoroalkyl substances (PFAS) in water presents a significant challenge for developing countries, requiring urgent attention. This review focuses on understanding the emergence of PFAS in drinking water, health concerns, and removal strategies for PFAS in water systems in developing countries. This review indicates the need for more studies to be conducted in many developing nations due to limited information on the environmental status and fate of PFAS. The health consequences of PFAS in water are enormous and cannot be overemphasized. Efforts are ongoing to legislate a national standard for PFAS in drinking water. Currently, there are few known mitigation efforts from African countries, in contrast to several developing nations in Asia. Therefore, there is an urgent need to develop economically viable techniques that could be integrated into large-scale operations to remove PFAS from water systems in the region. However, despite the success achieved with removing long-chain PFAS from water, more studies are required on strategies for eliminating short-chain moieties in water.

Graphical abstract

Image 1

Highlights

•Contamination of drinking water by PFAS is a serious problem in developing countries that requires attention.

• No single analysis method can comprehensively detect all the known PFAS in a single process.

• The legislation of national standards for PFAS is still ongoing.

• There is scant information on mitigation strategies for PFAS in water in developing countries.

• The cost implication of any technique for removing PFAS from water is not a one-way system.

Keywords

Emerging water contaminant
Per- and polyfluoroalkyl substances
Perfluoroalkyl acids
Photocatalysis
Water pollution
==== Body
pmc1 Introduction

Per- and polyfluoroalkyl substances (PFAS) are halogenated organic molecules of industrial applications that cut across food, textile, cosmetics, and household products. Despite the successes recorded with the use of PFAS, direct ingestion into the human system has health challenges, making it unfit for healthy living. Therefore, using some selected PFAS as bulk resources or additives in industrial production is prohibited [1]. Unfortunately, PFAS are currently detected in drinking and drinking water sources, a situation that calls for serious public health concerns and urgent attention.

PFAS are environmentally persistent substances [2] with health hazard concerns, making them environmentally unfriendly. The toxicological profile of most PFAS needs to be better understood, and with the growing concerns, there are reasons to discontinue their production. However, this move is unlikely and impractical because of the essential role PFAS plays in products associated with safety (e.g. fire retardant, building material, etc.) and health (surgical implants, surgical gloves, blood bags, orthopedic components, etc.). Generally, PFAS are a group of compounds containing the moiety –CnF2n+1 and –CnF2n–(n ≥ 1) in their structure [3,4]. Interestingly, other authors have included cyclic, aromatic, and substituted fluorinated compounds [5]. Some identified groups include perfluoroalkyl acids (PFAA), fluorotelomer-based substances, and perfluoroalkane sulfonyl fluoride (PASF)-based substances. These groups may be polymeric or non-polymeric substances. Examples of nonpolymeric substances include nonpolymeric PASF-based substances and non-polymeric fluorotelomer-based substances. This category encompasses various compounds such as perfluoroalkyl carbonyl fluoride (PACF)-based substances, perfluoroalkyl phosphinic acids (PFPIA)-based substances, cyclic PFAS, aromatic substances with fluorinated sidechains, per- and polyfluoroalkyl ethers, and hydrofluoroether. The polymeric substances include perfluoropolyether, fluoropolymers, sidechain fluorinated polymers, etc (Fig. 1).Fig. 1 Family tree of PFAS.

Fig. 1

PFAS are present in the environment and have generated global discussion due to their resistance to hydrolysis, biodegradation, and photooxidation [6,7]. The typical PFAS are perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorobutane sulfonic acid (PFBS), perfluorosulfonic acids (PFSA), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluorononanoic acid (PFNA), perfluorinated carboxylic acids (PFCA), perfluorohexane sulfonic acid (PFHxS), and perfluorohexanoic acid (PFHxA). PFAS in drinking water sources are a serious problem. Recently, a study reported PFAA and fluoroethers as major PFAS in the Cape Fear River, a drinking water source in California, USA [8]. The study was conducted from 2018 to 2021, which revealed an average of 3.4 kg/day of PFAS passing the river to enter the coastal marine water, putting about 1.5 million of the North Carolina population at risk. Rivers and groundwater along the Ganges River in India were examined to underscore PFAS content [9]. This study detected 15 PFAS, with the dominant being PFHxA (0.4–4.7 ng/L) and PFBS (<MQL to 10.2 ng/L), respectively, with short-chain PFAS being the most prevalent. Recently, PFAS were reported in untreated and processed drinking water samples collected from 18 water treatment plants in the Netherlands [10]. The water samples were classified into surface water and groundwater samples to better understand the distribution of PFAS in the collected samples from the treatment plant. The short-chain PFAS (300–1,100 ng/L) were the dominant group reported in the studied samples.

Studies have shown PFAS to be detrimental to human health and environmentally unfriendly [1], which indicates the importance of getting rid of them in water. However, they must be adequately detected and quantified before developing techniques for their removal in aqueous systems. Methods are being improved for rapid and adequate quantification of PFAS in water, especially the quantification of the -fluoro- species formed during water purification. Unfortunately, it has been discovered that PFAS are not completely removed from water by many of the wastewater treatment techniques [11]. Presently, there is still much to learn about the potential long-term effects of PFAS on both humans and the environment; the health risk linked to human exposure to PFAS is a serious concern. In many developed countries, a lot of studies have been conducted on the environmental impact assessment of PFAS to understand its fate and distribution with significant political and scientific attention. Though the situation is different in developing countries, such as those that are lagging behind in science and technology, there have been increasing efforts from a few countries in Asia and South America [12]. The information from many of the developing nations is still scant, and there is a need to assess the current PFAS status for better understanding. Therefore, this review aims to discuss the emergence of PFAS in water, health concerns, and their removal from water systems in developing nations.

2 Emergence and quantification of PFAS in the environmental water sample

2.1 Emergence of PFAS in water system

The emergence of PFAS in drinking water may be traced to point and nonpoint sources. Due to the fact that environmental chemical pollutants can decompose to generate stable PFAS under specific environmental circumstances they may act as chemical precursors for PFAS [13,14]. Several research investigations have shown that one of the sources of PFAS in surface water is drinking water treatment plants (DWTPs) or wastewater treatment plants (WWTPs) [15]. Moreover, the introduction of PFAS in environmental drinking water sources has been attributed to the discharge activities of sludge emanating from WWTPs or DWTPs into surface water without adequate treatment because a few of the decontamination steps may lead to the generation of PFAS [16]. Many WWTPs cannot completely remove PFAS or reduce it to the barest minimum, which may be considered insignificant. Many studies have confirmed this by detecting PFAS in tap and bottled drinking water. For example, a study investigated PFAS in 101 bottled water for sale in the US, revealing the presence of 15 PFAS (0.17–18.87 ng/L) consisting of C3–C10 PFCA, and C3–C6 and C8 PFSA [17]. Recently, 35 PFAS with concentrations ranging from 3.30 to 32.00 ng/L were detected in tap water samples collected from 42 locations in Barcelona [18]. The drinking water samples collected across 16 states in the US were analyzed to detect and quantify the presence of PFAS [19]. The results confirmed 26 unique PFAS in the analyzed water samples, with concentrations ranging from 1.90 to 234.50 ng/L. A study focusing on a small community in Alaska (Gustavus), US, studied drinking water from Gustavus residents for PFAS [7]. The study detected 14 PFAS from the collected water samples, including PFCA, PFSA, and fluorotelomer sulfonate (FTS), with concentrations ranging from undetected (ND) to 120 ng/L. Table 1 shows the detection of PFAS in tap and bottled water from some developing countries. The contamination is as high as 200 ng/L in tap water and 15 ng/L in bottled water. However, there is more information on PFAS contamination of surface water systems than on tap and bottled water in developing countries. The contamination of drinking water by PFAS is a global problem requiring urgent attention because of some of the associated health concerns. Many studies have been conducted in developed countries investigating end-used tap and bottled water to understand the quantity reaching final consumers; for example, bottled spring and natural mineral waters collected from France were analyzed, which revealed 10 PFAS (PFOS, PFHxS, and PFBS) in 40 brands of bottled water[31]. Studies in this direction are minimal in developing countries, which suggests the need for further investigations to understand the amount of PFAS that gets to the final consumers of bottled water and tap water in such countries. This understanding will also help project the health hazards that may have on the populace over a period of ingestion and bioaccumulation.Table 1 Detection of PFAS in tap and bottled water from some selected developing countries.

Table 1Country	Source	Sampling year	Concentration(ng/L)	Reference	
Brazil	Bottle water	2014	ND–15.00	[20]	
Turkey	Bottle water	2017–2018	0.08–0.90	[21]	
Ivory Coast	Bottle water	2015–2016	3.00	[22]	
Ghana	Tap water	2015	197–200	[23]	
India	Tap water	2006–2008	<0.083	[24]	
India	Treated water	2022–2023	20.40–48.71	[25]	
Turkey	Tap water	2017–2018	0.08–11.27	[21]	
Vietnam	Tap water	2014–2015	0.00–1.19	[26]	
China	Tap water	2015	1.40–175	[27]	
Brazil	Tap water	2014	ND–28.00	[20]	
China	Tap water	2021	1,490–2,150	[28]	
China	Tap water	2018–2019	4.59–365.04	[29]	
China	Tap water	2002–2006	<0.10–45.90	[30]	
ND, non-detectable; PFAS, per- and polyfluoroalkyl substances.

Studies have shown a widespread detection of PFAS in drinking water and drinking water sources from Europe, the Americas, Asia, and Australia [32]. Presently, information on PFAS from Africa is limited due to the inaccessibility of research facilities for routing environmental studies to monitor PFAS. However, PFOS, PFPeA, PFOA, PFHxA, and perfluorodecanoic acid (PFDA) were reported in drinking water and rivers in Ghana [24]. Table 2 presents some dominant PFAS detected in drinking water sources in several developing countries. The reported concentrations vary across sources, suggesting pollution of both surface and ground water systems. Data emanating from bottled and tap waters studied in Burkina Faso and Ivory Coast showed the presence of PFAS in samples collected from different locations [23]. Sediments and the river from the Vaal River revealed the presence of 15 PFAS, with PFOS being the most frequently detected from the studied sites [33]. Niger River in Mali (4.7 ng/L) and the Sabaki River estuary in Kenya (4.6 ng/L) were reported to be contaminated with PFOS [34]. A similar observation was reported from surface water samples collected from Nigeria, Egypt, Morocco, the Congo, Kenya, and Mauritius [35]. Many European countries have documented the occurrence of PFAS in surface water and commercially available drinking water [32]. The Mediterranean Rivers [36] and the Llobregat and Jucar Rivers in Spain [37,38] have been reported to be contaminated with PFAS. Similarly, PFAS has been reported in rural areas far from urban and industrial areas, suggesting the extensive impact of PFAS on environmental water systems, which shows the need for a detailed understanding of the fate of PFAS in the environment.Table 2 Dominant PFAS detected in drinking water sources in selected developing countries.

Table 2Country	Source	Dominant PFAS	Concentration (ng/L)	Year	Reference	
India	Surface water and groundwater	PFHxA	0.40–4.70	2014	[9]	
PFBS	<MQL–10.20	
PFBA	<MQL–9.20	
PFBS	<MQL–4.90	
India	Surface water	PFOA	<1.50–24.80	2018–2019	[39]	
PFOS	<1.20–13.90	
Kenya	Lake Victoria Gulf	PFOS	<0.40–2.53	2006–2007	[40]	
PFOA	<0.40–11.70	
Brazil	Surface water and groundwater	PFOA	11–718		[41]	
PFOS		
PFHpA		
Bangladesh		FTOHs	<LOQ–19	2020	[42]	
PFBA		
South Africa	Vaal River	PFBS	<LOQ–24.70	2014	[33]	
PFHxS	<LOQ–7.60	
PFOS	0.40–35.70	
PFHxA	<LOQ–20.30	
PFOA	0.60–4.60	
PFNA	<LOQ–1.80	
Mexico	Groundwater and surface water	PFBS	0.91–155.40	2020–2021	[43]	
PFPeA		
PFHxA		
Nigeria	River	PFOS	3.90–10.10	2016	[44]	
		PFOA	0.80–2.80	
Ethiopia	Lake Tana	PFOS	<0.05–0.22	2014	[45]	
PFOA	<0.28–0.69	
South Africa	Plankenburg River	PFBS	<LOQ	2014	[46]	
PFOS	<0.06–12.40	
PFBA	10.20–28.40	
PFOA	12.80–62.60	
PFNA	<LOQ	
Ghana	Pra and Kakum River	PFOS	77.20–277.00	2015	[24]	
PFOA	1.78–321.00	
Uganda	Lake	PFOS	1.60	2015	[47]	
PFOA	2.40	
Mexico	Wastewater treatment plant	PFBA	176.9 ± 3.3	2019	[48]	
PFHxA	133.4 ± 2.5	
PFHpA	116.6 ± 3.9	
PFOA	133.1 ± 3.5	
PFUnA	23.5 ± 6.5	
FTOHs, fluorotelomer alcohols; LOQ, limits of quantification; PFHxS, perfluorohexane sulfonic acid; PFHxA, perfluorohexanoic acid; PFBS, perfluorobutane sulfonic acid; PFNA, perfluorononanoic acid; PFDoDA, perfluorododecanoic acid; PFDA, perfluorodecanoic acid; PFBA, perfluorobutanoic acid; PFPeA, perfluoropentanoic acid.

A study in the Middle East revealed the presence of PFAS in Saudi Arabian coastal waters, detecting the presence of 12 PFAS in surface water up to 956 ng/L [49]. Saudi Arabia is the largest producer of desalinated water, and the presence of PFAS in drinking water is a challenge to the supply of safe drinking water in Saudi Arabia and many other Middle East countries. Fish samples collected from the Saudi Arabian Red Sea have shown the presence of PFAS; however, effluents from the WWTPs are reported to be the main contributor of PFAS to the Saudi Arabian biota [50]. There is scant information on the assessment of PFAS in water systems in the United Arab Emirates (UAE). Although there are published articles on other groups of water pollutants in UAE waters, but information on PFAS environmental contamination is scarce. This is also the case for many Middle Eastern countries. Recently, PFOS and PFOA were detected in water samples collected from the Karun River in Iran [51]. Similarly, PFAS have been detected in wastewater-irrigated farmland in Jordan [52]. A similar situation also existed in Turkey, with the detection of PFAS in tap and bottled water samples [22]. PFAS was reported in human serum and milk collected from patients in Lebanon involving 419 pregnant women, which may be linked to exposure to PFAS-contaminated drinking water [53]. Unfortunately, no serious monitoring has been documented for water systems from Kuwait [54]. Many countries in South America and the Caribbean have reported the detection of PFAS in surface water within the region [32]. The large-scale production and frequent use of PFAS-based pesticides in many South American countries have contributed to its environmental presence. These pesticides include sulfluramid, which contains ethyl perfluorooctane sulfonamide, a PFOS precursor [55,56]. Brazil is a major importer of sulfluramid to neighboring South American countries; a study reported that this activity within the years 2004–2015 could presumably contribute to the release of about 167–487 tons of PFOS/FOSA (perfluorooctane sulfonamide) into these South American environments [57]. When ethyl perfluorooctane sulfonamide gets into the environmental water system, it adsorbs into the sediment and converts to PFOS and FOSA. PFOS, and FOSA in ecological water systems (surface water and groundwater) studied in Brazil and Columbia have been linked to using sulfluramid pesticides [55,57].

Although there is a need for extensive study, a lot of efforts have been made to understand the fate of PFAS in the Asia–Pacific region. A study conducted in the Philippines, China, Thailand, and Japan revealed that the concentration of PFOS ranges from ND to 54 ng/L [32,58]. The concentration varied due to the choice of sampling location, data variability, and analysis method. Recent studies have shown the concentration of PFOS and PFOA from some sites studied in China to be in trace levels, such as 0.013 ng/L [59,60], while some other studies reported concentrations up to 1,590 ng/L [[60], [61], [62], [63]]. A study evaluated PFAS in rivers, drinking water sources, and various drinking water types in Qingdao, eastern China [64]. The study revealed that the concentration of PFAS in the river ranged from 28.3 to 292.2 ng/L, while that of tap water ranged from 20.5 to 29.9 ng/L. The study suggested a high level of PFAS loading in the suburban and rural rivers, which reflects the anthropogenic activities, and further estimated an annual PFAS loading of 5.9 t to Jiaozhou Bay. Although the concentration of the drinking water reservoir is lower than that of the river, achieving a complete removal of PFAS would not be a bad idea for water consumers in the city of Qingdao. An evaluation of the Indian River Lagoon and the Atlantic coast within Brevard County, Florida, revealed the presence of PFBA, PFBS, PFHxA, PFOA, PFDA, and PFOS [65]. Surface water samples collected were analyzed for 92 PFAS. Among the sites studied, the Banana River demonstrated the highest concentration of PFAS. PFBA, PFNA, and PFOA were found in 16 samples collected from the Periyar River with concentrations of PFBA between 58 and 2,174 ng/L, PFNA between 20 and 705 ng/L, and PFOA between 22 and 1,503 ng/L [66]. The Periyar River was chosen because it is the most contaminated flowing river in Kerala, India. As a flowing river, the concentration of PFAS was highest at the estuary, where PFOS concentration was reported to be 12,958 ng/L, attributed to contributions from industrial emissions emanating from nearby industries.

Apart from China, many of the developing countries in Asia, Africa, Europe, the Middle East, and North and South America need to conduct more studies to understand the distribution and fate of PFAS in environmental water systems as well as in drinking water supplies. The current information is scant, making it difficult to draw a logical conclusion in many countries. Compared to studies conducted on PFAS from the US, the United Kingdom, Germany, Japan, Canada, and other developed countries, information from most developing countries lacks depth and richness. The US has evaluated national data sets to gain insight into the concentration, sources, and composition of PFAS in drinking water [67], tremendous efforts have been put into developing national guidelines for handling PFAS [68]. In many European countries, efforts are ongoing to develop regulations for managing the emissions of PFAS, and there are established requirements for monitoring PFAS in drinking water [69,70], which are not available in most developing countries due to a lack of sufficient data set. This shortcoming calls for more research to help improve drinking water quality. While surface water remains the primary drinking water source in many nations, using recycled wastewater as a drinking water source is also promoted. Unfortunately, the PFAS in both recycled wastewater and WWTP sludge to surface water have negatively affected the use of these drinking water sources in many developing countries. Many personal care products, firefighting foams, textiles, aviation hydraulic fluid, electronics, protection nonstick coatings, and other consumer goods, have contributed to the release of PFAS into the environment [32]. Perfluorinated compounds are highly stable and difficult to degrade due to the magnitude of the C–F bonds that occur in their structures; however, partially fluorinated groups are less stable due to the low amount of the C–F bonds, permitting some level of degradation when mitigated. Such mitigation may lead to stable perfluorinated moieties, sometimes called precursor molecules for PFAS [71].

2.2 Quantification of PFAS in water sample

The detection and quantification of all known PFAS in matrix samples remains challenging, with only a limited number being adequately quantifiable using the analytical methods available [72]. The known analytical methods for monitoring PFAS and their precursors in drinking water systems rely on reference standards and isotope-labeled internal standards. The lack of sufficient PFAS standards has limited the detection and quantification of PFAS. Many known methods for sample preparation for analyzing, identifying, and quantifying PFAS require improvement. The sample pretreatment and extraction of PFAS from the sample matrix are achieved by solid-phase extraction (SPE) and may require an ion exchanger and elution with the most efficient solvent system. Several methods have been developed for PFAS analysis; for example, the standard DIN 38407-42 method of analysis with a lower limit of quantification (LOQ) is adequate for specific PFOA and PFOS with a LOQ of 10 ng/L [73,74]. However, with recent advancements, a LOQ of 1 ng/L is attainable with newly improved laboratory methods of analysis [72], most of which can quantify both short- and long-chain PFAS. The ISO 21675 demonstrates a LOQ of 0.2 ng/L, standing out for its low LOQ for analysis of 20 PFOA and PFOS with carbon chain lengths ranging from 4 to 13 atoms, which qualify the method as drinking water directives for the European Union (EU) [[75], [76], [77]].

The EN 17892 method, a European standard for PFAS in drinking water, was published by the Technical Committee on Water Analysis of the European Committee for Standardization (CEN), validating it for the analysis of 9 PFAS in drinking water [32]. However, there is a need to validate the application of the method for surface water and groundwater. Some selected analytical methods for analyzing PFAS in the complex matrix are presented in Table 3 [[98], [99], [100], [101], [102], [103]]. Method 537.1 is a modification of method 537 [78]. The method uses SPE and liquid chromatography-tandem mass spectrometry (LC–MS/MS) and is suitable for analyzing PFAS in drinking water at low ng/L. The method has been successfully used to monitor PFAS with high sensitivity in drinking water. Method 533 relies on isotope dilution ion exchange SPE and LC–MS/MS for the analysis of PFAS [79]. Many other methods are on the draft waiting list for validation. The U.S. Environmental Protection Agency (EPA), in collaboration with other agencies and departments, has published many draft methods that can help identify PFAS in water; Method 1633 can identify about 40 PFAS in landfill leachate, surface water, and groundwater, wastewater, and soil samples [80]. The EPA's analysis methods are meant to achieve analytical accuracy and precision. Many methods have also emerged [81]. There are hundreds of PFASs with different carbon chain lengths. Therefore, there is no single method of analysis that can cover all PFAS known. Two or more analytical methods might be combined to achieve wider identification and quantification of PFAS. There is a need to develop a comprehensive analysis method.Table 3 Selected analytical methods for PFAS quantification in water sample.

Table 3Method	Comment	Reference	
Method 537.1: determination of selected PFAS in drinking water by SPE and LC–MS/MS	Measures PFAS in drinking water using solid phase extraction and LC–MS/MS at low ng/L. It can detect and measure the short-chain PFAS in water, including the Gen-X groups.	[78]	
Method 537: determination of selected PFAS in drinking water by SPE and LC–MS/MS	The method can detect and measure selected PFAAs in water by SPE extraction and LC–MS/MS	[82]	
Method 533: determination of PFAS in drinking water by isotope dilution anion exchange SPE and LC–MS/MS	The method targets short-chain PFAS (C1–C12 only). This includes fluorotelomers, sulfonates, poly/perfluorinated ether carboxylic acids, PFAAs, and sulfonates.	[79]	
Method 8327: PFAS using external standard calibration and MRM LC–MS/MS	The method makes use of LC–MS/MS for detection and quantification of PFAS.	[83]	
Draft method 1633 and 1621	The method can test up to 40 PFAS compounds in wastewater, surface water, groundwater, soil, biosolids, sediment, landfill leachate, and fish tissue.	[80]	
SW-846 test method 0010: modified method of analysis	The method is good for semi-volatile PFAS. It uses an isotope dilution train approach for GC–MS targeted and nontargeted analysis.	[81]	
PFAAs, perfluoroalkyl acids; SPE, solid-phase extraction; LC–MS/MS, liquid chromatography/tandem mass spectrometry.

Some challenges arise during the quantification of PFAS in drinking water. For example, PFAS may adsorb on the walls of containers for bottled water, especially in the case of plastic or polymer containers. This observation may be associated with the functional groups present in PFAS, such as PFBS, PFOS, PFOA, PFBA, etc. Selecting a method for total organofluorine (TOF) in water depends on selectivity and inclusivity because it is necessary to remove fluoride interferences during analysis. When the technique is too inclusive, it does not help differentiate between organic and inorganic fluoride, which makes it difficult to estimate and quantify PFAS-related TOF in drinking water samples. There is no standard analytical method recommended for estimating TOF in a drinking water matrix. However, since other sources have no interferences, TOF can be easily quantified if the component PFAS is known in a simple single-PFAS water sample. Methods such as the extractable organofluorine (EOF) and adsorbable organofluorine (AOF) techniques are well-known [[84], [85], [86], [87]].

3 Regulation and guideline for PFAS in water

Due to the health challenges associated with PFAS, it is crucial to regulate and develop guidelines for handling them. Unfortunately, this is affected by analytical detection and social, economic, and political influences [88,89]. Several reports have indicated the need to set guidelines for PFAS. The persistence and bioaccumulation of PFAS have been reported in blood [90,91], drinking water, and some other foodstuffs [[92], [93], [94]]. PFAS can bioaccumulate in the human body more than most known water contaminants and have high health consequences even at low concentrations. PFAS has been a subject of discussion in the Stockholm Convention to monitor the impact of organic pollutants on human health and the environment. The EU regulation (2020/784) that amends the restriction on PFAS considered the use of PFOA and related compounds, which sets a maximum concentration of 0.025 mg/kg for PFOA while the maximum concentration for its related compounds was set at 1 mg/kg [94,95]. All plans to phase out the use of PFOS, PFOA, and their precursor molecules failed; therefore, the EPA made an effort to draft update values for PFOS (0.02 ng/L) and PFOA (0.004 ng/L) and set PFBS and Gen-X at 2,000 and 10 ng/L, respectively [88,96,97]. Interestingly, the National Health and Medical Research Council of Australia set a limit of 70 and 560 ng/L for PFOS + PFHxS and PFO, respectively [98,99]. Other countries, like Canada [32,100], Italy [32,101,102], Sweden [103,104] and Denmark [32,105] have made considerable progress. However, many developing countries do not have national guideline levels for PFAS in water.

The EPA has not established any national drinking water standards for PFAS. However, in 2016, the EPA finalized a nonregulatory advisory of 70 ng/L for PFOA and PFOS [106]. Some states in the US, such as Minnesota [32,107], New Jersey [32,108], Michigan [32,109,110], New York [32,111,112] and California [[113], [114], [115]] have set thresholds as guidelines for PFOA and PFOS. Due to the concern and urgency to regulate PFAS in water, some US states have proposed guidelines for drinking water sources (surface and underground water systems) based on health challenges [[116], [117], [118], [119]]. The use of long-chain PFAS is discouraged, and manufacturing industries are mandated to declare the type and concentration of PFAS used during the production process for regulatory purposes [88,117,120,121]. Effluents emanating from these industries must be treated to reduce PFAS load; unfortunately, there are no standards to ensure conformity among these industries. The EPA has tried to develop guidance levels but has not for drinking water permissibility levels [[120], [121], [122]]. The EPA reported a health advisory level for PFOA (0.004 ppt), PFOS (0.02 ppt), Gen-X (10 ppt), and PFBS (2,000 ppt) [32,123]. It is essential to set a global standard that can help the world. The long-chain PFAS are highly bioaccumulative in humans, many of which are lipophilic [106]. In principle, water guidelines are developed based on toxicity and exposure factors. However, this takes time and continuous research effort with financial commitment. Most states in the US depend on animal toxicological data to develop their current guidelines for PFOA and PFOS at state levels. In contrast, the risk assessment is generally based on nonthreshold assumptions [92,106,124,125]. Many developed countries manage PFAS by limiting their use in everyday products, monitoring occurrence, and developing guidelines for handling and processing. Most of the least developed countries rely on EPA guidelines for operations, and some even adopt EPA standards for regulating drinking water contaminants as their national standards. Consequently, it is essential for governments to invest more in scientific development and activities that promote the capacity to establish drinking water standards and effectively regulate water contaminants.

Previously, the EU published a document on the commercialization and production of PFOS and its derivatives [126,127], superseding the Regulation (EU) 2019/1021 [127,128]. The EU made several interventions, with the conclusion that the impact of derivatives of PFOS and PFOA is not well understood, which suggests the need for more studies to enhance the development of an all-encompassing or well-informed regulation [129]. In 2019, the Norwegian Environment Agency put forth a proposal to the Stockholm Convention, recommending the inclusion of PFHxS and its derivates on the list of persistent organic pollutants [127]. Interestingly, with the development of technology to determine PFAS at low concentrations, the European Commission proposed the ban of all PFAS in firefighting foams across the EU, which led to the assessment by the European Chemicals Agency (ECHA) on the risk and possible strategies [130,131]. The proposal further prohibits using, marketing, formulating, or compounding any form of PFAS in industrial or commercially available products [132]. Many other European countries have also submitted proposals to ECHA, but efforts are ongoing to bring these into comprehensive and enforceable legislation.

The US and Canada have made remarkable efforts to protect the environment from the negative impact of PFAS. The US federal government and state legislatures have covered many grounds in developing guidelines for some states through the support of the EPA. For example, in 2021, the EPA announced the PFAS strategy roadmap, which was a success in helping and safeguarding communities in the US from PFAS contamination [133,134]. In 2023, the EPA developed national drinking water regulations establishing maximum levels for PFNA, PFBS, PFOA, Gen-X, PFOS, and PFHxS [127]. Furthermore, with the support of the EPA, lawmakers have enacted more than 250 PFAS-related bills to monitor and regulate their maximum levels. In South America, Brazil has made tremendous efforts to control the contamination by PFAS in the environment, and many of these initiatives are still ongoing [135,136]. In Asia, China is leading in the fight to eradicate PFAS, and has put 18 PFAS on the list of priority control chemicals [127]. Japan, Thailand, India, Vietnam, Indonesia, and Singapore are also making efforts. In 2022, Vietnam listed PFAS on the drafted Decree No. 82/2022/ND-CP as chemicals to be regulated [127]. Africa is behind in setting guideline levels for PFAS in water. However, many African countries endorsed the Stockholm Convention to develop national implementation plans but failed to include PFAS in their national implementation plans [137,138]. Africa needs to catch up with efforts from other regions of the world, and African countries need to do more by investing resources in eliminating PFAS in environmental water systems.

Many developing countries are not encouraging, and the efforts directed toward developing regulations for the provision of clean drinking water are poor. It is important that governments in developing countries promote and fund initiatives that ensure the enactment of policies supporting the provision of clean drinking water free of PFAS. Among the developing countries, the BRICS (Brazil, Russia, India, China, and South Africa) are the financially and scientifically strong countries that may help support other developing countries by driving initiatives and policies aimed at achieving SDG 6 for the provision of clean drinking water. The BRICS may need to enhance scientific development by promoting activities that will fund scientific exchange programs or initiatives where the stronger developing countries can help the least developed through knowledge transfer, skill acquisition, and funding of scientific activities. In fact, there is a need to support collaborative research and guidelines for policy formation to assist the least developed countries. Governments in developing countries need to strengthen their political will to abide by the Stockholm Convention and invest more in monitoring regulated and unregulated water pollutants. There is an urgent need to support and strengthen government agencies saddled with the responsibility of environmental monitoring and impact assessments. The governments in many developing countries need to work-the-talk by investing in education, research, and development. It is also important to develop locally sourced or invented strategies for managing PFAS contamination in water. Such strategies should be indigenous for sustainability and easy management instead of embracing techniques that are expensive for developing countries to sustain. A strong and unwavering regulatory framework will help developing countries because, if the framework is enforced, the pollution can be easily managed, reducing spending on treatment.

4 Health effects of PFAS contaminated water

Most studies on the toxicological effects of PFAS focused on PFOA and PFOS. PFAS is widely used, and it was not until a few years ago that its health challenges were considered a problem. Production and distribution of PFOA and PFOS have been discontinued in many nations, but they continue to be detected in the blood of human beings [139]. The presence of PFAS in drinking water may lead to high cholesterol levels, hormonal disruption, testicular and kidney cancer, high blood pressure, and a decrease in vaccine potency in children [[140], [141], [142]]. PFAS at trace doses are unhealthy, which may affect immune and metabolic systems [[143], [144], [145]]. Unfortunately, only a few PFAS are studied to understand their toxicity profile. Their interactive mode, half-life, absorption, and long-term toxicity effects are little known. More attention must be given to understanding the toxicity profile of the unavoidable or essential PFAS class to understand better how to handle them for safety when used in industrial products. Some studies have revealed that PFOA may cause testicular and kidney cancer [[146], [147], [148]]. Studies have shown that the currently promoted short-chain PFAS (Gen-X) used as a replacement for the discontinued PFAS is also becoming environmentally unfriendly, and studies have revealed bioaccumulation in humans with possible health adverse effects [[149], [150], [151], [152]]. This situation has become worrisome, suggesting the need to regulate PFAS, especially in drinking water.

PFAS health-related challenges are a serious concern, and care must be taken in handling the devastating effect this may have on the public health. A study on the level of PFAS in blood demonstrated that PFAS can contaminate the human system [153]. The study was conducted in Europe, using 1,957 children and teenagers as participants, and all the samples tested positive for PFNA, PFOS, PFHxS, and PFOA. Unfortunately, there are challenges in assessing the information needed to understand the toxicological impact of PFAS because several hundred PFAS and their derivatives are known, making it difficult to screen them all. Furthermore, the chemical nature and structures of their derivatives are limitations to studying these PFAS, as they can be metamorphosed into derivatives under different environmental conditions. PFAS are absorbed in the gastrointestinal tract and can bind to blood serum protein to be transported to organs in the human body [154,155]. A study has revealed that PFOS and PFOA may have a half-life of up to 5 years in the human body [156]. The carbon chain length of PFAS was reported to be inversely proportional to its elimination from the human body [157]. Even though the short-chain PFAS are known to bioaccumulate less than the long-chain moieties, the bioaccumulation of Gen-X and ADONA (dodecafluoro-3H-4,8-dioxanonanoate) are not well understood, and there is a need for more research to be conducted in this regard [158,159]. Recent studies have revealed placental abnormalities in mice treated with Gen-X with reduced thyroid hormone and elevated peroxisome proliferator-activated receptors (PPAR)-regulated gene expression levels in the livers [[160], [161], [162]]. While a birth defect was reported with F-53B in zebrafish [163], a study by Gaballah et al. [164] revealed no toxicity. Other studies have shown converse results to reports of established toxicity with short-chain PFAS; such conflicting conclusions call for more studies to understand the actual hazards associated with the short-chain moieties.

Data on the composition and processing conditions of products containing PFAS are kept confidential by business owners, making it difficult to follow through on the chemical characteristics of PFAS and possible changes in structure that may have occurred through product formation. Many animal studies are taking a turn from rodents to zebrafish as models for the toxicological study of PFAS. A few of the studies leveraged immune suppression, hepatic/lipid metabolic toxicity, tumor induction, obesity, developmental toxicity, and endocrine disruption [165]. Apart from the danger associated with long-chain PFAS, the Gen-X group has shown an alteration in liver function, leading to apoptosis in mice and fish [162,166]. The review revealed the need for more studies on the short-chain PFAS groups to understand their safety profile. Studies have shown that long-chain PFAS are contaminants of high concern because of the health hazards associated with their presence in the human body [167]. Therefore, it has become necessary to replace them, although the replacement process is not straightforward [150,168]. Although short-chain PFAS has received attention as a promising replacement, recent studies are indicating possible hazards for humans from the use of short-chain PFAS [165,169,170]. This revelation suggests the need for more studies to be conducted in this area. The fate of long-chain and short-chain PFAS under environmental conditions in many developing countries is not well understood due to a lack of monitoring evaluation. This makes it difficult to know the possible transformation that may occur to PFAS under the environmental conditions in the countries. Previous studies showed dysfunctional mitochondria in mice [171], with steatosis being a common feature [165,172]. Despite the understanding of the health hazards of PFAS, details on the mode of action of PFAS in the human body are not known to date. However, a few studies have linked this to the activation of some nuclear receptors such as PPARβ/δ, liver X receptor α, Erα, PPARα, CAR, PPARγ, and pregnane X (PXR) [[173], [174], [175], [176]]. There is a need to conduct more studies that will involve changing the process parameters in exposure to PFAS; this may include the time of exposure, dose-dependent study, the effect of animal sex, etc., to have a better understanding of the mode of action and adaptation strategy of the animals being studied in the in vivo experiment.

5 Removal of PFAS from water

Many techniques have been reported for removing PFAS from water systems [177,178]. The strong C–F bond makes many of these techniques, such as flocculation, biodegradation, sedimentation, oxidation, and disinfection, inefficient for the removal of PFAS from water [11,179,180]. Many known conventional water treatment methods cannot completely remove PFAS from water because of their high structural stability. Membrane technology, photocatalysis, and adsorption are promising technologies for achieving the removal of PFAS in water. A few studies have combined separation and destruction techniques to remove PFAS from the water system. The separation techniques include the use of adsorption, ion exchange, and membrane techniques, while the destruction techniques make use of thermal destruction, advanced oxidation processes, electrochemical oxidation, and advanced reduction [[181], [182], [183], [184], [185], [186], [187], [188]]. The merits and demerits of some of the selected techniques for removing PFAS from water systems are compared in Table 4 [183,[217], [218], [219], [220], [221], [20], [24], [25], [26], [27], [28], [29], [30], [39], [40], [41], [42], [43]].Table 4 Merit and demerit of some selected techniques for treating PFAS-contaminated water system.

Table 4Merit	Demerit	Reference	
Adsorption: powder (PAC) and granular (GAC) activated carbon	
I: Can efficiently remove PFAS from water even in the presence of other contaminants.
II: Nondestructive, good for low concentrations (ng/L) of PFAS in water.
III: Can efficiently remove long-chain PFAS from water.
IV: Relatively affordable.	I: May exhibit poor regeneration capacity, which makes it expensive to reuse.
II: Cannot efficiently remove short-chain PFAS from water due to weak hydrophobic interaction.
III: Performance may be hampered by the presence of organic molecules.	[183,[189], [190], [191], [192],[193], [194], [195], [196]]	
Membrane filtration	
I: Very efficient for mixed matrix contaminated water treatment.
II: Can efficiently remove both short and long-chain PFAS from the water matrix.
III: Nondestructive, efficient for the removal of both organic and inorganic water contaminants.
IV: Water purification can be achieved within a short time with high performance.	I: Fouling is a major problem that can reduce performance.
II: High energy may be required, which increases process cost.
III: In some cases, membrane regeneration may be expensive, which increases process cost.	[190,[197], [198], [199], [200],201]	
Ion-exchange separation	
I: Can efficiently remove ionic and long-chain PFAS at low concentrations.
II: Exhibits higher performance than the use of activated carbon.
III: Cheaper operating cost than the use of activated carbon.	I: Less efficient for mixed matrix contaminated water treatment.
II: Not efficient for short-chain PFAS.
III: Resin regeneration for reuse is expensive.	[190,192,194,[202], [203], [204]]	
Photocatalysis	
I: Efficient for low concentration, photostability, fast electron transfer.
II: High surface area to volume ratio and rapid diffusion rate.
III: Improved degradation efficiency.
IV: Absorbs visible light and controllable bandgaps.	I: Fast recombination of photogenerated charge carriers is a destructive process.
II: Cytotoxicity might be a problem.
III: Agglomeration might be a challenge.
IV: Toxicity and poor recovery from water sample.	[205,206]	

The adsorption techniques using activated carbon and other materials as adsorbents have shown encouraging success. The technique is suitable for low concentrations of PFAS and can efficiently remove the long-chain PFAS from water systems; however, the poor regeneration capacity of most of the reported adsorbents is a challenge [[189], [190], [191], [192]]. Many low-cost adsorbents have made the technique cheap and affordable. Still, competing interferences in a complex matrix water sample hamper the technique's performance due to challenges from selectivity and low uptake of PFAS from complex matrix systems. The cheap and abundant availability of biobased materials in developing countries makes adsorption a suitable option for the removal of PFAS from water systems. A few research works from developing countries have focused on the use of bio-sorbents for this purpose. A good example is the study on biochar filters as complements for sand filters for removing PFAS from water [207]. Many such studies have been conducted by scientists from developing countries in developed countries with the hope of acquiring skills to help developing countries. The membrane technology is outstanding for treating complex matrices of water systems, making it suitable for municipal use. The membrane technique can sufficiently handle short- and long-chain PFAS in the water system. In the case of a complex polluted water matrix, it can efficiently remove inorganic and organic pollutants in water. However, the performance of membrane technology is hampered by fouling, which is a significant challenge to this technique [190,[197], [198], [199], [200]]. Furthermore, the process may become expensive due to high-pressure requirements and energy costs. The ion exchange technique suits ionic and long-chain PFAS at low concentrations. Unfortunately, it is also inefficient for complex mixed matrices of water samples. When completely spent, replacing or regenerating the resin may increase process costs.

The photocatalytic process is destructive, and PFAS cannot be reconcentrated at the end of the removal process because they are converted to smaller molecules like CO2 and H2O. The photocatalytic process is suitable for low concentrations of PFAS. One advantage of the process is that the energy bandgap required for the photodegradation can be modified to suit the light range needed for the process; unfortunately, one of the major challenges of the photocatalytic process is the recombination of the electron (e−)/hole (h+) pair [205,206]. It is essential to note that when a complex matrix of highly polluted water such as municipal wastewater, landfill leachate, or industrial wastewater is to be treated, it is paramount to conduct a pretreatment on the wastewater to be purified to ease PFAS removal [208].

Efforts are ongoing to develop sustainable and efficient methods for the removal of PFAS from water. WWTPs are one of the contributors of PFAS to environmental drinking water sources in developing countries. Most WWTPs in developing countries cannot efficiently remove PFAS from wastewater because many of them were not designed to cater to PFAS in water. Many water corporations and water agencies in developing countries are trying to improve the capacity of their WWTPs to remove PFAS. The situation is very challenging in the least developed countries that do not have the financial capacity to purchase or develop new WWTPs in rural and urban communities to provide clean tap water. It is difficult to pinpoint the method for the removal of PFAS from water in developing countries because this information is not concisely available. Apart from the many innovative ways for removing PFAS from water published by authors from Asia [[209], [210], [211], [212]], many other developing countries are still behind.

6 Current perspectives, cost evaluation, and future recommendations

Currently, the focus is on using short-chain and novel PFAS instead of long-chain moieties. More novel and short-chain PFAS are expected to be utilized under strict monitoring. Therefore, efforts should be made to better understand the fate and morphological changes that may occur by exposing these groups of PFAS to environmental factors. It is also vital to develop better and more rapid methods for detection, quantification, and treatment of these groups of PFAS in the water system. Most studies on PFAS in drinking water have focused on the target group of PFAS, with limited information on the other groups classified as nontarget PFAS. The most studied PFAS are PFOA and PFOS; however, more studies are still required on the nontarget group of PFAS, even though information on the short-chain and Gen-X is limited.

Ionic PFAS are rarely studied, despite the danger associated with them. It is necessary to study the nature of ionic PFAS in the environmental water system to understand the lower molecules they disintegrate into when exposed to environmental factors like temperature, pressure, etc. These lower molecules may have toxic effects. The ionic PFAS includes zwitterionic and cationic PFAS. Presently, there is no generally accepted standard analytical method of analysis for most ionic PFAS, including zwitterionic and cationic PFAS. This may be attributed to insufficient isotope-labeled analogs for electrospray ionization, ESI (+) PFAS, which is primarily problematic [89]. Proper identification of some PFAS is challenging because they may exist in different isomer forms. There is a need to have a priority list of PFAS identified in drinking water and its sources to ensure effective quantification and monitoring, which will aid in the development of allowable standards for global practice.

Adequate quantification of TOF in sources of drinking water, such as surface water and groundwater samples, is challenging and requires further investigation. TOF must be correctly evaluated for a comprehensive evaluation of PFAS in water to avoid doubt in interpreting the data. Combustion ion chromatography (CIC) has demonstrated low sensitivity toward organofluorines [89] and does not suggest the structure of the organofluorines, limiting the use of CIC for quantifying organofluorines in drinking water samples with low organofluorine content.

The lack of state-of-the-art equipment for the analytical evaluation of samples collected from different water sites in some developing countries is a setback for understanding the status of PFAS in such countries. There is a large data gap concerning the occurrence or status of PFAS in drinking water and environmental drinking water sources (including WWTPs, surface water and groundwater systems) in developing countries. Therefore, it is expedient for researchers in developed and developing nations to collaborate to effectively understand the nature of PFAS in drinking water in science- and technology-lagging countries around the world. There is a need for water agencies and governments in different countries to increase funding for water studies to understand the occurrence and fate of PFAS in water. There is no sufficient data to establish the molecular interaction of PFAS in the human body. There are lots of questions to be answered. Unfortunately, data on the effect of short-chain PFAS on the human system are inconsistent [213], indicating that the threat of both long and short-chain PFAS is not entirely understood [145], suggesting the need for more studies to be conducted. It is difficult to completely rely on extrapolated data from the laboratory animal studies as a model for final human results; therefore, more data are required.

The cost evaluation of running the present techniques for removing PFAS from water is essential to understanding the feasibility and economic viability of the techniques. Treating PFAS-contaminated water systems is expensive. For example, Brunswick County, North Carolina, utilized reverse osmosis to treat the PFAS-contaminated Cape Fear River watershed, which cost $99 million and will require an annual expense of $2.9 million [214]. Different tools have been designed to estimate the cost of removing PFAS from water; many of these tools consider many inputs and outputs, which included the cost of infrastructure, consumables, labor, service fees, transportation, etc. Many have also applied to the EPA-derived work breakdown structure [215,216] to estimate the treatment cost, which covers derived system-level, add-on, indirect capital, administrative, and annual operation and maintenance costs. A study estimated the cost of purifying PFAS-contaminated water using GAC and ion exchange resin to establish economic sustainability [217]. The authors considered the initial flow rate for the treatment plant to be 0.740 million gallons/day and an initial concentration of PFAS to be 3 × 10−3 mg/L while resin contact was 2 min/vessel. The direct cost of running GAC ($105,001) is double that of the resin ($52,248), suggesting the resin system is more economical. The study further considered the social cost of carbon concerning utilizing GAC and resin and found the total social cost of carbon for GAC ($6,966) is higher than that of the resin system ($4,332), which further buttresses the fact that the ion exchange technique is a cost-efficient technique when compared with GAC. A recently reported life cycle treatment cost for PFAS combined the EPA-derived work breakdown structure and the manufacturer price for adsorbent to arrive at an annual operation cost for GAC and ion exchange resin ($19,879). The study also confirmed the yearly cost of running GAC ($78,445) is higher than that of the resin system ($11,246) for removing PFAS in water [218]. Similarly, during an annual EPA meeting in 2020, the cost of running water treatment for PFAS removal using reverse osmosis, GAC, and ion exchange techniques were compared to provide PFAS-free water for over 2,000 households. The team gave an annual cost of $49,000,000, $48,000,000, and $50,000,000 for reverse osmosis, GAC, and ion exchange techniques, respectively [219].

The cost comparison for removing PFAS by GAC and ion exchange resin at a pilot scale was conducted in a continuous flow at a Bäcklösa DWTP in Uppsala, Sweden [190]. The cost comparison was based on 80% recovery, factoring in predetermined operation parameters such as particle filter replacement, energy, and cost of the antiscalant membrane. The annual operation cost revealed that the ion exchange resin sorption process is more economical than the GAC process. A landfill leachate in Thailand was investigated for its net present cost using a reverse osmosis membrane system to remove PFAS [220]. The estimated cost involving an evaporated pond system was $577.9 million, with a unit cost of ranging from $1.72 to $2.71 m−3. In comparison, a nonevaporated pond system would cost $391.9 million at a unit cost of $1.06 and $2.09 m−3. For a photocatalytic degradation process of PFAS in water, the cost was evaluated using indium oxides at a 254 nm light source requiring 2106 kWh/m3 and was found to cost $295 m−3 for a treatment time above 11 h [221].

The cost evaluation for the photocatalytic degradation of PFAS is scant. More studies are needed to understand the cost of water purification via photocatalytic degradation, adsorption, and membrane technique. Although the EPA-derived work breakdown structure has been developed to determine the process cost, there may be a need to modify the structure as different factors may contribute to the direct and indirect costs due to location-specific factors or variations in process specificity. However, the EPA-derived work breakdown structure may serve as a template to work with or modify in other regions of the world for cost analysis. The disposal of the spent membrane, adsorbent, and catalyst requires further study. Therefore, there is a need to develop an efficient and cost-effective system for disposing of or handling them when they are completely spent. This is an interesting area of research, finding applications for them instead of environmental disposal or incineration.

7 Conclusion

Contamination of drinking water by PFAS is a serious problem in developing countries that requires attention. PFAS has been reported in surface water and groundwater systems with the help of different analysis methods. With the several known PFAS, no single analysis method can comprehensively detect all the known PFAS in a single process. The legislation of national standards for PFAS is still ongoing. However, few developed and developing countries have established guidelines for handling PFAS in water. Many of the known treatment processes for PFAS in water combine separation and destruction techniques for complete removal. Unfortunately, complete defluorination is still a challenge. Despite the EPA-derived work breakdown structure, the cost implication of any technique for removing PFAS from water is not a one-sided system but requires the consideration of different factors that may be region-specific, process-specific, or situation-based. With the discontinuation of long-chain PFAS, there is a need to focus on understanding the fate and detailed health implications of the short-chain moieties in developing countries.

CRediT authorship contribution statement

A.A.: investigation, writing, conceptualization; Q.L.: supervision, writing, conceptualization, proof reading.

Declaration of competing interests

The authors have declared no conflicts of interest.

Acknowledgment

The authors appreciate the support received from the Fulbright African Research Scholar Program grant (PS00349260 ).
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References

1 Panieri E. Baralic K. Djukic-Cosic D. Buha Djordjevic A. Saso L. PFAS molecules: a major concern for the human health and the environment Toxics 10 2022 44 10.3390/toxics10020044 35202231
2 Cousins I.T. Ng C.A. Wang Z. Scheringer M. Why is high persistence alone a major cause of concern? Environ. Sci. Process. Impacts 21 2019 781 792 10.1039/C8EM00515J 30973570
3 Buck R.C. Franklin J. Berger U. Conder J.M. Cousins I.T. de Voogt P. Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins Integr. Environ. Assess. Manag. 7 2011 513 541 10.1002/ieam.258 21793199
4 Organisation for Economic Co-operation and Development (OECD) Toward a new comprehensive global database of per-and polyfluoroalkyl substances (PFASs): summary report on updating the OECD 2007 list of per- and polyfluoroalkyl substances (PFASs) http://www.oecd.org/chemicalsafety/portal-perfluorinated-chemicals/ 2018
5 Glüge J. Scheringer M. Cousins I.T. DeWitt J.C. Goldenman G. Herzke D. An overview of the uses of per- and polyfluoroalkyl substances (PFAS) Environ. Sci.: Process. Impacts 22 2020 2345 2373 10.1039/D0EM00291G 33125022
6 Wang Z. DeWitt J.C. Higgins C.P. Cousins I.T. A never-ending story of per- and polyfluoroalkyl substances (PFASs)? Environ. Sci. Technol. 51 2017 2508 2518 10.1021/acs.est.6b04806 28224793
7 Babayev M. Capozzi S.L. Miller P. McLaughlin K.R. Medina S.S. Byrne S. PFAS in drinking water and serum of the people of a southeast Alaska community: a pilot study Environ. Pollut. 305 2022 119246 10.1016/j.envpol.2022.119246
8 Pétré M.A. Salk K.R. Stapleton H.M. Ferguson P.L. Tait G. Obenour D.R. Per- and polyfluoroalkyl substances (PFAS) in river discharge: modeling loads upstream and downstream of a PFAS manufacturing plant in the Cape Fear watershed, North Carolina Sci. Total Environ. 831 2022 154763 10.1016/j.scitotenv.2022.154763
9 Sharma B.M. Bharat G.K. Tayal S. Larssen T. Bečanová J. Karásková P. Perfluoroalkyl substances (PFAS) in river and ground/drinking water of the Ganges River Basin: emissions and implications for human exposure Environ. Pollut. 208 2016 704 713 10.1016/j.envpol.2015.10.050 26561452
10 Sadia M. Nollen I. Helmus R. Ter Laak T.L. Béen F. Praetorius A. Occurrence, fate, and related health risks of PFAS in raw and produced drinking water Environ. Sci. Technol. 57 2023 3062 3074 10.1021/acs.est.2c06015 36779784
11 Crone B.C. Speth T.F. Wahman D.G. Smith S.J. Abulikemu G. Kleiner E.J. Occurrence of per- and polyfluoroalkyl substances (PFAS) in source water and their treatment in drinking water Crit. Rev. Environ. Sci. Technol. 49 2019 2359 2396 10.1080/10643389.2019.1614848 32831535
12 Singh K. Kumar N. Kumar Yadav A. Singh R. Kumar K. Per-and polyfluoroalkyl substances (PFAS) as a health hazard: current state of knowledge and strategies in environmental settings across Asia and future perspectives Chem. Eng. J. 475 2023 145064 10.1016/j.cej.2023.145064
13 Wang T. Wang P. Meng J. Liu S. Lu Y. Khim J.S. A review of sources, multimedia distribution and health risks of perfluoroalkyl acids (PFAAs) in China Chemosphere 129 2015 87 99 10.1016/j.chemosphere.2014.09.021 25262946
14 Ruyle B.J. Pickard H.M. LeBlanc D.R. Tokranov A.K. Thackray C.P. Hu X.C. Isolating the AFFF signature in coastal watersheds using oxidizable PFAS precursors and unexplained organofluorine Environ. Sci. Technol. 55 2021 3686 3695 10.1021/acs.est.0c07296 33667081
15 Wang Y.-Q. Hu L.-X. Liu T. Zhao J.-H. Yang Y.-Y. Liu Y.-S. Per- and polyfluoralkyl substances (PFAS) in drinking water system: target and non-target screening and removal assessment Environ. Int. 163 2022 107219 10.1016/j.envint.2022.107219
16 Szabo D. Coggan T.L. Robson T.C. Currell M. Clarke B.O. Investigating recycled water use as a diffuse source of per- and polyfluoroalkyl substances (PFASs) to groundwater in Melbourne, Australia Sci. Total Environ. 644 2018 1409 1417 10.1016/j.scitotenv.2018.07.048 30743853
17 Chow S.J. Ojeda N. Jacangelo J.G. Schwab K.J. Detection of ultrashort-chain and other per- and polyfluoroalkyl substances (PFAS) in U.S. bottled water Water Res. 201 2021 117292 10.1016/j.watres.2021.117292
18 Cserbik D. Redondo-Hasselerharm P.E. Farré M.J. Sanchís J. Bartolomé A. Paraian A. Human exposure to per- and polyfluoroalkyl substances and other emerging contaminants in drinking water NPJ Clean Water 6 2023 16 10.1038/s41545-023-00236-y
19 Pelch K.E. McKnight T. Reade A. 70 analyte PFAS test method highlights need for expanded testing of PFAS in drinking water Sci. Total Environ. 876 2023 162978 10.1016/j.scitotenv.2023.162978
20 Schwanz T.G. Llorca M. Farré M. Barceló D. Perfluoroalkyl substances assessment in drinking waters from Brazil, France and Spain Sci. Total Environ. 539 2016 143 152 10.1016/j.scitotenv.2015.08.034 26360456
21 Endirlik B.Ü. Bakır E. Boşgelmez İ.İ. Eken A. Narin İ. Gürbay A. Assessment of perfluoroalkyl substances levels in tap and bottled water samples from Turkey Chemosphere 235 2019 1162 1171 10.1016/j.chemosphere.2019.06.228 31561307
22 Kaboré H.A. Duy S.V. Munoz G. Méité L. Desrosiers M. Liu J. Worldwide drinking water occurrence and levels of newly-identified perfluoroalkyl and polyfluoroalkyl substances Sci. Total Environ. 616–617 2018 1089 1100 10.1016/j.scitotenv.2017.10.210
23 Essumang D.K. Eshun A. Hogarh J.N. Bentum J.K. Adjei J.K. Negishi J. Perfluoroalkyl acids (PFAAs) in the Pra and Kakum River Basins and associated tap water in Ghana Sci. Total Environ. 579 2017 729 735 10.1016/j.scitotenv.2016.11.035 27887832
24 Mak Y.L. Taniyasu S. Yeung L.W. Lu G. Jin L. Yang Y. Perfluorinated compounds in tap water from China and several other countries Environ. Sci. Technol. 43 2009 4824 4829 10.1021/es900637a 19673271
25 Koulini G.V. Nambi I.M. Occurrence of forever chemicals in Chennai waters, India Environ. Sci. Eur. 36 2024 60 10.1186/s12302-024-00881-1
26 Lam N.H. Cho C.R. Kannan K. Cho H.S. A nationwide survey of perfluorinated alkyl substances in waters, sediment and biota collected from aquatic environment in Vietnam: distributions and bioconcentration profiles J. Hazard. Mater. 323 2017 116 127 10.1016/j.jhazmat.2016.04.010 27106518
27 Tan K.-Y. Lu G.-H. Piao H.-T. Chen S. Jiao X.-C. Gai N. Current contamination status of perfluoroalkyl substances in tapwater from 17 cities in the Eastern China and their correlations with surface waters Bull. Environ. Contam. Toxicol. 99 2017 224 231 10.1007/s00128-017-2109-3 28528484
28 Jiao E. Larsson P. Wang Q. Zhu Z. Yin D. Kärrman A. Further insight into extractable (organo)fluorine mass balance analysis of tap water from Shanghai, China Environ. Sci. Technol. 57 2023 14330 14339 10.1021/acs.est.3c02718 37710968
29 Chen R. Li G. He Y. Pan L. Yu Y. Shi B. Field study on the transportation characteristics of PFASs from water source to tap water Water Res. 198 2021 117162 10.1016/j.watres.2021.117162
30 Jin Y.H. Liu W. Sato I. Nakayama S.F. Sasaki K. Saito N. PFOS and PFOA in environmental and tap water in China Chemosphere 77 2009 605 611 10.1016/j.chemosphere.2009.08.058 19775722
31 Le Coadou L. Le Ménach K. Labadie P. Dévier M.H. Pardon P. Augagneur S. Quality survey of natural mineral water and spring water sold in France: monitoring of hormones, pharmaceuticals, pesticides, perfluoroalkyl substances, phthalates, and alkylphenols at the ultra-trace level Sci. Total Environ. 603–604 2017 651 662 10.1016/j.scitotenv.2016.11.174
32 Kurwadkar S. Dane J. Kanel S.R. Nadagouda M.N. Cawdrey R.W. Ambade B. Per- and polyfluoroalkyl substances in water and wastewater: a critical review of their global occurrence and distribution Sci. Total Environ. 809 2022 151003 10.1016/j.scitotenv.2021.151003
33 Groffen T. Wepener V. Malherbe W. Bervoets L. Distribution of perfluorinated compounds (PFASs) in the aquatic environment of the industrially polluted Vaal River, South Africa Sci. Total Environ. 627 2018 1334 1344 10.1016/j.scitotenv.2018.02.023 30857097
34 Šebková K. The Stockholm convention, global monitoring plan and its implementation in regional and global monitoring reports Persistent Organic Pollutants in Human Milk 2023 Springer International Publishing 3 73 10.1007/978-3-031-34087-1_3
35 Magulova K. Priceputu A. Global monitoring plan for persistent organic pollutants (POPs) under the Stockholm Convention: triggering, streamlining and catalyzing global POPs monitoring Environ. Pollut. 217 2016 82 84 10.1016/j.envpol.2016.01.022 26794340
36 Lorenzo M. Campo J. Farré M. Pérez F. Picó Y. Barceló D. Perfluoroalkyl substances in the Ebro and Guadalquivir River Basins (Spain) Sci. Total Environ. 540 2016 191 199 10.1016/j.scitotenv.2015.07.045 26250865
37 Campo J. Pérez F. Masiá A. Picó Y. la Farré M. Barceló D. Perfluoroalkyl substance contamination of the Llobregat River ecosystem (Mediterranean area, NE Spain) Sci. Total Environ. 503–504 2015 48 57 10.1016/j.scitotenv.2014.05.094
38 Campo J. Lorenzo M. Pérez F. Picó Y. la Farré M. Barceló D. Analysis of the presence of perfluoroalkyl substances in water, sediment and biota of the Jucar River (E Spain). Sources, partitioning and relationships with water physical characteristics Environ. Res. 147 2016 503 512 10.1016/j.envres.2016.03.010 26974364
39 Hariharan G. Sunantha G. R.S R. Darwin R. Purvaja R. Ramesh R. Early detection of emerging persistent perfluorinated alkyl substances (PFAS) along the east coast of India Sci. Total Environ. 902 2023 166155 10.1016/j.scitotenv.2023.166155
40 Orata F. Quinete N. Werres F. Wilken R.-D. Determination of perfluorooctanoic acid and perfluorooctane sulfonate in Lake Victoria Gulf water Bull. Environ. Contam. Toxicol. 82 2009 218 222 10.1007/s00128-008-9543-1 18791652
41 Stefano P.H.P. Roisenberg A. D'Anna Acayaba R. Roque A.P. Bandoria D.R. Soares A. Occurrence and distribution of per-and polyfluoroalkyl substances (PFAS) in surface and groundwaters in an urbanized and agricultural area, Southern Brazil Environ. Sci. Pollut. Res. Int. 30 2023 6159 6169 10.1007/s11356-022-22603-x 35987853
42 Morales-McDevitt M.E. Dunn M. Habib A. Vojta S. Becanova J. Lohmann R. Poly- and perfluorinated alkyl substances in air and water from Dhaka, Bangladesh Environ. Toxicol. Chem. 41 2022 334 342 10.1002/etc.5255 34793599
43 Travis R.E. Beisner K.R. Wilkins K. Jasmann J.R. Keefe S.H. Barber L.B. Assessment of Per-and Polyfluoroalkyl Substances in Water Resources of New Mexico, 2020–21 2024 10.3133/sir20235129 (ver. 1.2, April 2024): U.S. Geological Survey Scientific Investigations Report 2023–5129
44 Ololade I.A. Oladoja N.A. Ololade O.O. Oloye F.F. Adeola A.O. Alabi A.B. Geographical distribution of perfluorooctanesulfonate and perfluorooctanoate in selected rivers from Nigeria J. Environ. Chem. Eng. 6 2018 4061 4069 10.1016/j.jece.2018.06.020
45 Ahrens L. Gashaw H. Sjöholm M. Gebrehiwot S.G. Getahun A. Derbe E. Poly- and perfluoroalkylated substances (PFASs) in water, sediment and fish muscle tissue from Lake Tana, Ethiopia and implications for human exposure Chemosphere 165 2016 352 357 10.1016/j.chemosphere.2016.09.007 27665295
46 Fagbayigbo B.O. Opeolu B.O. Fatoki O.S. Olatunji O.S. Validation and determination of nine PFCS in surface water and sediment samples using UPLC-QTOF-MS Environ. Monit. Assess. 190 2018 346 10.1007/s10661-018-6715-2 29766315
47 Dalahmeh S. Tirgani S. Komakech A.J. Niwagaba C.B. Ahrens L. Per- and polyfluoroalkyl substances (PFASs) in water, soil and plants in wetlands and agricultural areas in Kampala, Uganda Sci. Total Environ. 631 2018 660 667 10.1016/j.scitotenv.2018.03.024 29539594
48 Rodríguez-Varela M. Durán-Álvarez J.C. Jiménez-Cisneros B. Zamora O. Prado B. Occurrence of perfluorinated carboxylic acids in Mexico City's wastewater: a monitoring study in the sewerage and a mega wastewater treatment plant Sci. Total Environ. 774 2021 145060 10.1016/j.scitotenv.2021.145060
49 Ali A.M. Higgins C.P. Alarif W.M. Al-Lihaibi S.S. Ghandourah M. Kallenborn R. Per- and polyfluoroalkyl substances (PFASs) in contaminated coastal marine waters of the Saudi Arabian Red Sea: a baseline study Environ. Sci. Pollut. Res. Int. 28 2021 2791 2803 10.1007/s11356-020-09897-5 32894446
50 Ali A.M. Sanden M. Higgins C.P. Hale S.E. Alarif W.M. Al-Lihaibi S.S. Legacy and emerging per- and polyfluorinated alkyl substances (PFASs) in sediment and edible fish from the Eastern Red Sea Environ. Pollut. 280 2021 116935 10.1016/j.envpol.2021.116935
51 Takdastan A. Babaei A.A. Jorfi S. Ahmadi M. Tahmasebi Birgani Y. Jamshidi B. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water and edible fish species of Karun River, Ahvaz, Iran: spatial distribution, human health, and ecological risk assessment Int. J. Environ. Health Res. 34 2024 803 814 10.1080/09603123.2023.2168630 36709497
52 Shigei M. Ahrens L. Hazaymeh A. Dalahmeh S.S. Per- and polyfluoroalkyl substances in water and soil in wastewater-irrigated farmland in Jordan Sci. Total Environ. 716 2020 137057 10.1016/j.scitotenv.2020.137057
53 Mahfouz M. Harmouche-Karaki M. Matta J. Mahfouz Y. Salameh P. Younes H. Maternal serum, cord and human milk levels of per- and polyfluoroalkyl substances (PFAS), association with predictors and effect on newborn anthropometry Toxics 11 2023 455 10.3390/toxics11050455 37235269
54 Alshemmari H. Inventories and assessment of POPs in the State of Kuwait as a basis for Stockholm Convention implementation Emerg. Contam. 7 2021 88 98 10.1016/j.emcon.2021.02.003
55 Rauert C. Harner T. Schuster J.K. Eng A. Fillmann G. Castillo L.E. Atmospheric concentrations of new persistent organic pollutants and emerging chemicals of concern in the group of Latin America and Caribbean (GRULAC) region Environ. Sci. Technol. 52 2018 7240 7249 10.1021/acs.est.8b00995 29846065
56 De Clercq A. PFOS-vervuiling: Juridische Aspecten 2023 Master’s thesis, Ghent University https://libstore.ugent.be/fulltxt/RUG01/003/142/962/RUG01-003142962_2023_0001_AC.pdf
57 Gilljam J.L. Leonel J. Cousins I.T. Benskin J.P. Is ongoing sulfluramid use in South America a significant source of perfluorooctanesulfonate (PFOS)? Production inventories, environmental fate, and local occurrence Environ. Sci. Technol. 50 2016 653 659 10.1021/acs.est.5b04544 26653085
58 Fiedler H. van der Veen I. de Boer J. Global interlaboratory assessments of perfluoroalkyl substances under the Stockholm Convention on persistent organic pollutants Trends Anal. Chem. 124 2020 115459 10.1016/j.trac.2019.03.023
59 Baabish A. Sobhanei S. Fiedler H. Priority perfluoroalkyl substances in surface waters – a snapshot survey from 22 developing countries Chemosphere 273 2021 129612 10.1016/j.chemosphere.2021.129612
60 Pan Y. Zhang H. Cui Q. Sheng N. Yeung L.W.Y. Sun Y. Worldwide distribution of novel perfluoroether carboxylic and sulfonic acids in surface water Environ. Sci. Technol. 52 2018 7621 7629 10.1021/acs.est.8b00829 29749740
61 Chen C. Lu Y. Zhang X. Geng J. Wang T. Shi Y. A review of spatial and temporal assessment of PFOS and PFOA contamination in China Chem. Ecol. 25 2009 163 177 10.1080/02757540902918321
62 Lu Z. Song L. Zhao Z. Ma Y. Wang J. Yang H. Occurrence and trends in concentrations of perfluoroalkyl substances (PFASs) in surface waters of Eastern China Chemosphere 119 2015 820 827 10.1016/j.chemosphere.2014.08.045 25218980
63 Li Y. Li J. Zhang L. Huang Z. Liu Y. Wu N. Perfluoroalkyl acids in drinking water of China in 2017: distribution characteristics, influencing factors and potential risks Environ. Int. 123 2019 87 95 10.1016/j.envint.2018.11.036 30502598
64 Lu G. Shao P. Zheng Y. Yang Y. Gai N. Perfluoroalkyl substances (PFASs) in rivers and drinking waters from Qingdao, China Int. J. Environ. Res. Public Health 19 2022 5722 10.3390/ijerph19095722 35565116
65 Griffin E.K. Aristizabal-Henao J. Timshina A. Ditz H.L. Camacho C.G. da Silva B.F. Assessment of per- and polyfluoroalkyl substances (PFAS) in the Indian River Lagoon and Atlantic coast of Brevard County, FL, reveals distinct spatial clusters Chemosphere 301 2022 134478 10.1016/j.chemosphere.2022.134478
66 Binu K.R. Yamashita N. Prabhasankar V.P. Praveenkumarreddy Y. Shenoy J.K. Balakrishna K. A first report of perfluoroalkyl substances (PFAS) in a large west-flowing river in southern India Kumar M. Mohapatra S. Impact of COVID-19 on Emerging Contaminants 2022 Springer Nature Singapore 16 10.1007/978-981-19-1847-6_1
67 Guelfo J.L. Adamson D.T. Evaluation of a national data set for insights into sources, composition, and concentrations of per- and polyfluoroalkyl substances (PFASs) in U.S. drinking water Environ. Pollut. 236 2018 505 513 10.1016/j.envpol.2018.01.066 29427949
68 Langenbach B. Wilson M. Per- and polyfluoroalkyl substances (PFAS): significance and considerations within the regulatory framework of the USA Int. J. Environ. Res. Public Health 18 2021 11142 10.3390/ijerph182111142
69 Dettori M. Arghittu A. Deiana G. Castiglia P. Azara A. The revised European Directive 2020/2184 on the quality of water intended for human consumption. A step forward in risk assessment, consumer safety and informative communication Environ. Res. 209 2022 112773 10.1016/j.envres.2022.112773
70 Cordner A. Brown P. Cousins I.T. Scheringer M. Martinon L. Dagorn G. PFAS contamination in Europe: generating knowledge and mapping known and likely contamination with “expert-reviewed” journalism Environ. Sci. Technol. 58 2024 6616 6627 10.1021/acs.est.3c09746 38569050
71 Göckener B. Fliedner A. Rüdel H. Fettig I. Koschorreck J. Exploring unknown per- and polyfluoroalkyl substances in the German environment – the total oxidizable precursor assay as helpful tool in research and regulation Sci. Total Environ. 782 2021 146825 10.1016/j.scitotenv.2021.146825
72 Brunn H. Arnold G. Körner W. Rippen G. Steinhäuser K.G. Valentin I. PFAS: forever chemicals—persistent, bioaccumulative and mobile. Reviewing the status and the need for their phase out and remediation of contaminated sites Environ. Sci. Eur. 35 2023 20 10.1186/s12302-023-00721-8
73 Lechner M. Nachweis und Eintrag perfluorierter Tenside (PFT) in Lebensmittel 2014 Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
74 Trautmann A.M. Schell H. Schmidt K.R. Mangold K.-M. Tiehm A. Electrochemical degradation of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in groundwater Water Sci. Technol. 71 2015 1569 1575 10.2166/wst.2015.143 26442500
75 Miserli K. Athanasiou V. Boti V. Hela D. Konstantinou I. Determination of PFAS in wastewaters and natural waters by solid phase extraction and UHPLC LTQ/Orbitrap MS for assessing occurrence and removals Case Stud. Chem. Environ. Eng. 8 2023 100505 10.1016/j.cscee.2023.100505
76 Backhaus T. Commentary on the EUCommission's proposal for amending the water framework directive, the groundwater directive, and the directive on environmental quality standards Environ. Sci. Eur. 35 2023 22 10.1186/s12302-023-00726-3
77 Novak Babič M. Marolt G. Imperl J. Breskvar M. Džeroski S. Gunde-Cimerman N. Effect of location, disinfection, and building materials on the presence and richness of culturable mycobiota through oligotrophic drinking water systems J. Fungi 9 2023 1086 10.3390/jof9111086
78 Shoemaker J. Tettenhorst D.R. DT Method 537.1 Determination of Selected Per-and Polyflourinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) 2020 U.S. Environmental Protection Agency Washington, DC
79 Rosenblum L. Wendelken S. Method 533: Determination of Per-and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry, Tandem Mass Spectrometry 2019 U.S. Environmental Protection Agency Washington, DC 52
80 Jack R. Lodge S. Robinson A. Johnson T. Khan A. Lord H. Comparison of PFAS sample preparation between WAX+ dispersive GCB and WAX/GCB cartridges from water and soil extracts per draft EPA 1633 18 11 2022 28 33
81 Rehman A.U. Crimi M. Andreescu S. Current and emerging analytical techniques for the determination of PFAS in environmental samples Trends Environ. Anal. Chem. 37 2023 e00198 10.1016/j.teac.2023.e00198
82 Shoemaker J.A. Grimmett P.E. Boutin B.K. Method 537: Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/tandem Mass Spectrometry (LC/MS/MS), Tandem Mass Spectrometry (LC/MS/MS) 2009 U.S. Environmental Protection Agency https://cfpub.epa.gov/si/si_public_file_download.cfm?p_download_id=525468
83 Jacob C.C. Martins C.P. Atkins A.R. Jack R.F. Direct Analysis of Selected Per-and Polyfluorinated Alkyl Substances (PFAS) in Ground, Surface, and Waste Water by LC-MS/MS 2019 Thermo Fisher Scientific
84 Schöpel M. Jacobs G. Jordens J. van Ermen G. Voorspoels S. Krause M. Analytical Methods for PFAS in Products and the Environment 2022 Nordic Council of Ministers 10.6027/temanord2022-510
85 Nakayama S.F. Yoshikane M. Onoda Y. Nishihama Y. Iwai-Shimada M. Takagi M. Worldwide trends in tracing poly- and perfluoroalkyl substances (PFAS) in the environment Trends Anal. Chem. 121 2019 115410 10.1016/j.trac.2019.02.011
86 Joudan S. Liu R. D'Eon J.C. Mabury S.A. Unique analytical considerations for laboratory studies identifying metabolic products of per- and polyfluoroalkyl substances (PFASs) Trends Anal. Chem. 124 2020 115431 10.1016/j.trac.2019.02.032
87 Winchell L.J. Wells M.J.M. Ross J.J. Fonoll X. Norton J.W. Kuplicki S. Analyses of per- and polyfluoroalkyl substances (PFAS) through the urban water cycle: toward achieving an integrated analytical workflow across aqueous, solid, and gaseous matrices in water and wastewater treatment Sci. Total Environ. 774 2021 145257 10.1016/j.scitotenv.2021.145257
88 Cordner A. De La Rosa V.Y. Schaider L.A. Rudel R.A. Richter L. Brown P. Guideline levels for PFOA and PFOS in drinking water: the role of scientific uncertainty, risk assessment decisions, and social factors J. Expo. Sci. Environ. Epidemiol. 29 2019 157 171 10.1038/s41370-018-0099-9 30622333
89 Teymoorian T. Munoz G. Vo Duy S. Liu J. Sauvé S. Tracking PFAS in drinking water: a review of analytical methods and worldwide occurrence trends in tap water and bottled water ACS EST Water 3 2023 246 261 10.1021/acsestwater.2c00387
90 Schmidt C.W. TSCA 2.0: a new era in chemical risk management Environ. Health Perspect. 124 2016 A182 A186 10.1289/ehp.124-a182 27689758
91 Rayasam S.D.G. Koman P.D. Axelrad D.A. Woodruff T.J. Chartres N. Toxic substances control act (TSCA) implementation: how the amended law has failed to protect vulnerable populations from toxic chemicals in the United States Environ. Sci. Technol. 56 2022 11969 11982 10.1021/acs.est.2c02079 35980084
92 United States Environmental Protection Agency Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS), Office of Water (4304T) 2016 Health and Ecological Criteria Division EPA Washington, DC, USA https://www.epa.gov/sites/default/files/2016-05/documents/pfos_health_advisory_final-plain.pdf
93 Xie S. Wang T. Liu S. Jones K.C. Sweetman A.J. Lu Y. Industrial source identification and emission estimation of perfluorooctane sulfonate in China Environ. Int. 52 2013 1 8 10.1016/j.envint.2012.11.004 23266910
94 Ramírez Carnero A. Lestido-Cardama A. Vazquez Loureiro P. Barbosa-Pereira L. Rodríguez Bernaldo de Quirós A. Sendón R. Presence of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in food contact materials (FCM) and its migration to food Foods 10 2021 1443 10.3390/foods10071443 34206351
95 European Commission Commission Delegated regulation (EU) 2020/784 of 8 April 2020 amending Annex I to regulation (EU) 2019/1021 of the European Parliament and of the Council as regards the listing of perfluorooctanoic acid (PFOA), its salts and PFOA-related compounds Official Journal of the European Union 2020 32020R30784 http://data.europa.eu/eli/reg_del/2020/784/oj
96 United States Environmental Protection Agency Drinking Water Health Advisories for PFOA and PFOS 2016 https://www.epa.gov/sites/default/files/2016-06/documents/drinkingwaterhealthadvisories_pfoa_pfos_updated_5.31.16.pdf
97 Cotruvo J.A. Goldhaber S.B. Cohen A.J.B. EPA's unprecedented interim drinking water health advisories for PFOA and PFOS Ground Water 61 2023 301 303 10.1111/gwat.13303 36807312
98 Wyrwoll P.R. Manero A. Taylor K.S. Rose E. Quentin Grafton R. Measuring the gaps in drinking water quality and policy across regional and remote Australia NPJ Clean Water 5 2022 32 10.1038/s41545-022-00174-1
99 Balasooriya B.M.J.K. Rajapakse J. Gallage C. A review of drinking water quality issues in remote and indigenous communities in rich nations with special emphasis on Australia Sci. Total Environ. 903 2023 166559 10.1016/j.scitotenv.2023.166559
100 Longpré D. Lorusso L. Levicki C. Carrier R. Cureton P. PFOS, PFOA, LC-PFCAS, and certain other PFAS: a focus on Canadian guidelines and guidance for contaminated sites management Environ. Technol. Innov. 18 2020 100752 10.1016/j.eti.2020.100752
101 Patrocinio R.d.V. World Health Organization, Keeping Our Water Clean: The Case of Water Contamination in the Veneto Region, Italy 2017 https://www.who.int/europe/publications/i/item/9789289052467
102 Mastrantonio M. Bai E. Uccelli R. Cordiano V. Screpanti A. Crosignani P. Drinking water contamination from perfluoroalkyl substances (PFAS): an ecological mortality study in the Veneto Region, Italy Eur. J. Public Health 28 2018 180 185 10.1093/eurpub/ckx066 28541558
103 Lindfeldt E. Per- and polyfluorinated alkyl substances in municipal drinking water in Sweden, Master’s thesis 2021 Uppsala University https://www.uppsatser.se/uppsats/f6377aa28b/
104 Nyholm N. Fires that never really went out: A spatial investigation of whether fire extinguishing efforts (2001-2015) can be linked to elevated levels of PFAS in surface water, fish and sediment in Stockholm, Solna and Sundbyberg municipalities Master’s thesis, Stockholm University 2021 https://www.uppsatser.se/uppsats/7fb625d01c/
105 Shekhawat N. Use of per and polyfluoroalkyl substances (PFAS) in cosmetics and their effects on human health Int. J. Food Nutr. Sci. 11 2022 93 96 https://www.ijfans.org/uploads/paper/6edc7ca6004c394f379febbd5a8eb244.pdf
106 Post G.B. Recent US state and federal drinking water guidelines for per- and polyfluoroalkyl substances Environ. Toxicol. Chem. 40 2021 550 563 10.1002/etc.4863 32845526
107 Smalling K.L. Bradley P.M. Romanok K.M. Elliot S.M. de Lambert J. Focazio M.J. Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA Environ. Sci.: Water Res. Technol. 9 2023 1813 1828 10.1039/D3EW00066D
108 The New Jersey Department of Environmental Protection 2024 New Jersey Statewide Water Supply Plan 2024 https://dep.nj.gov/water-supply-plan/
109 Whitley J.M. Laws, Regulations and Action Plans for Per-And Polyfluoroalkyl Substances Found in Michigan Drinking Water Supplies 2019
110 Craig D. Source Identification of Per-and Poly-Fluoroalkyl Substances (PFAS) in Cedar Lake, Alcona and Iosco County, Michigan Master’s thesis, North Carolina State University 2022
111 Gerrard M.B. McTiernan E. Regulation of polyfluoroalkyl chemicals in New York N.Y.L.J., March 9, 2022 2022 https://scholarship.law.columbia.edu/faculty_scholarship/3216
112 W. Regulation, Standards for PFOA and PFOS, NJ DEP'T ENVTL. PROT. (Apr. 1, 2019).
113 Pace C. Balazs C. Bangia K. Depsky N. Renteria A. Morello-Frosch R. Inequities in drinking water quality among domestic well communities and community water systems, California, 2011‒2019 Am. J. Public Health 112 2022 88 97 10.2105/AJPH.2021.306561 34936392
114 Olivieri A.W. Pecson B. Crook J. Hultquist R. California water reuse—past, present and future perspectives Wastewater Treatment and Reuse – Present and Future Perspectives in Technological Developments and Management Issues 2020 Elsevier 5 111 10.1016/bs.apmp.2020.07.002
115 Umunna I.L. Blacker L.S. Hecht C.E. Edwards M.A. Altman E.A. Patel A.I. Water safety in California public schools following implementation of school drinking water policies Prev. Chronic Dis. 17 2020 E166 10.5888/pcd17.200366 33416472
116 Abunada Z. Alazaiza M.Y.D. Bashir M.J.K. An overview of per- and polyfluoroalkyl substances (PFAS) in the environment: source, fate, risk and regulations Water 12 2020 3590 10.3390/w12123590
117 Brennan N.M. Evans A.T. Fritz M.K. Peak S.A. von Holst H.E. Trends in the regulation of per- and polyfluoroalkyl substances (PFAS): a scoping review Int. J. Environ. Res. Public Health 18 2021 10900 10.3390/ijerph182010900
118 Longsworth S.G. Processes & Considerations for Setting State PFAS Standards 2020 ECOS Washington, DC, USA
119 Hagarty A. United States Analysis of the Regulatory Inception of Per-and Polyfluoroalkyl Substances (PFAS) in Drinking Water Policy Among States and Review of Regulatory Efforts Made by the Federal Environmental Protection Agency 2023 Southern Illinois University at Edwardsville
120 Dean W.S. Adejumo H.A. Caiati A. Garay P.M. Harmata A.S. Li L. A framework for regulation of new and existing PFAS by EPA J. Sci. Policy Gov. 16 2020 1 14
121 Garnick L. Massarsky A. Mushnick A. Hamaji C. Scott P. Monnot A. An evaluation of health-based federal and state PFOA drinking water guidelines in the United States Sci. Total Environ. 761 2021 144107 10.1016/j.scitotenv.2020.144107
122 Humphreys E.H. Tiemann M. PFAS and Drinking Water: Selected EPA and Congressional Actions CRS Report, 2020
123 Wasel O. King H. Choi Y.J. Lee L.S. Freeman J.L. Differential developmental neurotoxicity and tissue uptake of the per- and polyfluoroalkyl substance alternatives, GenX and PFBS Environ. Sci. Technol. 57 2023 19274 19284 10.1021/acs.est.3c05023 37943624
124 U.S. Environmental Protection Agency Guidelines for Carcinogen Risk Assessment, Washington, DC 2005
125 Post G.B. Gleason J.A. Cooper K.R. Key scientific issues in developing drinking water guidelines for perfluoroalkyl acids: contaminants of emerging concern PLoS Biol. 15 2017 e2002855 10.1371/journal.pbio.2002855
126 Camino-Sánchez F.J. Zafra-Gómez A. Cantarero-Malagón S. Vílchez J.L. Validation of a method for the analysis of 77 priority persistent organic pollutants in river water by stir bar sorptive extraction in compliance with the European Water Framework Directive Talanta 89 2012 322 334 10.1016/j.talanta.2011.12.037 22284499
127 Schiavone C. Portesi C. PFAS: a review of the state of the art, from legislation to analytical approaches and toxicological aspects for assessing contamination in food and environment and related risks Appl. Sci. 13 2023 6696 10.3390/app13116696
128 Grobelak A. Kowalska A. Charpt 2—Emerging environmental contaminants—current status, challenges, and technological solutions in: H. Sarma, D.C. Dominguez, W.-Y. Lee (Eds.), Emerging Contaminants in the Environment 2022 Elsevier, Amsterdam, The Netherlands 39 53 10.1016/b978-0-323-85160-2.00010-x
129 Benford D. De Boer J. Carere A. Di Domenico A. Johansson N. Schrenk D. Opinion of the scientific panel on contaminants in the food chain on perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and their salts EFSA J. 653 2008 1 131
130 Mussabek D. Söderman A. Imura T. Persson K.M. Nakagawa K. Ahrens L. PFAS in the drinking water source: analysis of the contamination levels, origin and emission rates Water 15 2022 137 10.3390/w15010137
131 IARC Working Group on the Identification of Carcinogenic Hazards to Humans Occupational Exposure as a Firefighter Lyon (FR): International Agency for Research on Cancer IARC Monographs on the Identification of Carcinogenic Hazards to Humans, No. 132 2023 https://www.ncbi.nlm.nih.gov/books/NBK597253/
132 European Chemicals Agency (ECHA) Annex XV Restriction Report: Proposal for a Restriction Substance Name 2019 Intentionally Added Microplastics https://echa.europa.eu/documents/10162/05bd96e3-b969-0a7c-c6d0-441182893720
133 Thomas T. Malek A. Arokianathar J. Haddad E. Matthew J. Global regulations around PFAS: the past, the present and the future Int. Chem. Regul. Law Rev. 6 2023 3 17
134 U.S. Environmental Protection Agency PFAS strategic roadmap: EPA's commitments to action 2021–2024, EPA-100-K-21-002 https://www.epa.gov/pfas/pfas-strategic-roadmap-epas-commitments-action-2021-2024 2021
135 Barbosa Machado Torres F. Guida Y. Weber R. Machado Torres J.P. Brazilian overview of per- and polyfluoroalkyl substances listed as persistent organic pollutants in the Stockholm convention Chemosphere 291 2022 132674 10.1016/j.chemosphere.2021.132674
136 Guida Y. Torres F.B.M. Barizon R.R.M. Assalin M.R. Rosa M.A. Confirming sulfluramid (EtFOSA) application as a precursor of perfluorooctanesulfonic acid (PFOS) in Brazilian agricultural soils Chemosphere 325 2023 138370 10.1016/j.chemosphere.2023.138370
137 Groffen T. Nkuba B. Wepener V. Bervoets L. Risks posed by per- and polyfluoroalkyl substances (PFAS) on the African Continent, emphasizing aquatic ecosystems Integr. Environ. Assess. Manag. 17 2021 726 732 10.1002/ieam.4404 33650734
138 Ssebugere P. Sillanpää M. Matovu H. Wang Z. Schramm K.W. Omwoma S. Environmental levels and human body burdens of per- and poly-fluoroalkyl substances in Africa: a critical review Sci. Total Environ. 739 2020 139913 10.1016/j.scitotenv.2020.139913
139 Wee S.Y. Aris A.Z. Revisiting the “forever chemicals”, PFOA and PFOS exposure in drinking water NPJ Clean Water 6 2023 57 10.1038/s41545-023-00274-6
140 Negri E. Metruccio F. Guercio V. Tosti L. Benfenati E. Bonzi R. Exposure to PFOA and PFOS and fetal growth: a critical merging of toxicological and epidemiological data Crit. Rev. Toxicol. 47 2017 482 508 10.1080/10408444.2016.1271972 28617200
141 DeWitt J.C. Blossom S.J. Schaider L.A. Exposure to per-fluoroalkyl and polyfluoroalkyl substances leads to immunotoxicity: epidemiological and toxicological evidence J. Expo. Sci. Environ. Epidemiol. 29 2019 148 156 10.1038/s41370-018-0097-y 30482935
142 Pelch K.E. Reade A. Kwiatkowski C.F. Merced-Nieves F.M. Cavalier H. Schultz K. The PFAS-Tox database: a systematic evidence map of health studies on 29 per- and polyfluoroalkyl substances Environ. Int. 167 2022 107408 10.1016/j.envint.2022.107408
143 Lewis R.C. Johns L.E. Meeker J.D. Serum biomarkers of exposure to perfluoroalkyl substances in relation to serum testosterone and measures of thyroid function among adults and adolescents from NHANES 2011-2012 Int. J. Environ. Res. Public Health 12 2015 6098 6114 10.3390/ijerph120606098 26035660
144 U.S. Agency for Toxic Substances and Disease Registry Toxicological profile for perfluoroalkyls Released May 2021 https://www.atsdr.cdc.gov/ToxProfiles/tp200-p.pdf
145 Sunderland E.M. Hu X.C. Dassuncao C. Tokranov A.K. Wagner C.C. Allen J.G. A review of the pathways of human exposure to poly- and perfluoroalkyl substances (PFASs) and present understanding of health effects J. Expo. Sci. Environ. Epidemiol. 29 2019 131 147 10.1038/s41370-018-0094-1 30470793
146 Steenland K. Fletcher T. Stein C.R. Bartell S.M. Darrow L. Lopez-Espinosa M.J. Review: evolution of evidence on PFOA and health following the assessments of the C8 science panel Environ. Int. 145 2020 106125 10.1016/j.envint.2020.106125
147 Barry V. Winquist A. Steenland K. Perfluorooctanoic acid (PFOA) exposures and incident cancers among adults living near a chemical plant Environ. Health Perspect. 121 2013 1313 1318 10.1289/ehp.1306615 24007715
148 Nicole W. PFOA and cancer in a highly exposed community: new findings from the C8 science panel Environ. Health Perspect. 121 2013 A340 10.1289/ehp.121-A340 24284021
149 Gordon S.C. Toxicological evaluation of ammonium 4, 8-dioxa-3H-perfluorononanoate, a new emulsifier to replace ammonium perfluorooctanoate in fluoropolymer manufacturing Regul. Toxicol. Pharmacol. 59 2011 64 80 10.1016/j.yrtph.2010.09.008 20875479
150 Wang Z. Cousins I.T. Scheringer M. Hungerbühler K. Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors Environ. Int. 60 2013 242 248 10.1016/j.envint.2013.08.021 24660230
151 Buck R.C. Toxicology Data for Alternative “Short-chain” Fluorinated Substances. Toxicological Effects of Perfluoroalkyl and Polyfluoroalkyl Substances 2015 In: J. DeWitt (Ed.), Toxicological Effects of Perfluoroalkyl and Polyfluoroalkyl Substances. Molecular and Integrative Toxicology. Humana Press, Cham. 51 477 10.1007/978-3-319-15518-0_17
152 Kabadi S.V. Fisher J. Aungst J. Rice P. Internal exposure-based pharmacokinetic evaluation of potential for biopersistence of 6:2 fluorotelomer alcohol (FTOH) and its metabolites Food Chem. Toxicol. 112 2018 375 382 10.1016/j.fct.2018.01.012 29331735
153 Richterová D. Govarts E. Fábelová L. Rausová K. Martin L.R. Gilles L. PFAS levels and determinants of variability in exposure in European teenagers–Results from the HBM4EU aligned studies (2014–2021) Int. J. Hyg. Environ. Health 247 2023 114057
154 Jensen A.A. Leffers H. Emerging endocrine disrupters: perfluoroalkylated substances Int. J. Androl. 31 2008 161 169 10.1111/j.1365-2605.2008.00870.x 18315716
155 Wang Z. Zhang T. Wu J. Wei X. Xu A. Wang S. Male reproductive toxicity of perfluorooctanoate (PFOA): rodent studies Chemosphere 270 2021 128608 10.1016/j.chemosphere.2020.128608
156 Chambers W.S. Hopkins J.G. Richards S.M. A review of per- and polyfluorinated alkyl substance impairment of reproduction Front. Toxicol. 3 2021 732436 10.3389/ftox.2021.732436
157 Lau C. Perfluorinated compounds, molecular, clinical and environmental toxicology Andreas L. Environmental Toxicology vol. 3 2012 Springer Basel 47 86
158 Brendel S. Fetter É. Staude C. Vierke L. Biegel-Engler A. Short-chain perfluoroalkyl acids: environmental concerns and a regulatory strategy under REACH Environ. Sci. Eur. 30 2018 9 10.1186/s12302-018-0134-4 29527446
159 Munoz G. Liu J. Vo Duy S. Sauvé S. Analysis of F-53B, Gen-X, ADONA, and emerging fluoroalkylether substances in environmental and biomonitoring samples: a review Trends Environ. Anal. Chem. 23 2019 e00066 10.1016/j.teac.2019.e00066
160 Conley J.M. Lambright C.S. Evans N. Strynar M.J. McCord J. McIntyre B.S. Adverse maternal, fetal, and postnatal effects of hexafluoropropylene oxide dimer acid (GenX) from oral gestational exposure in sprague-dawley rats Environ. Health Perspect. 127 2019 37008 10.1289/EHP4372
161 Conley J.M. Lambright C.S. Evans N. McCord J. Strynar M.J. Hill D. Hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX) alters maternal and fetal glucose and lipid metabolism and produces neonatal mortality, low birthweight, and hepatomegaly in the Sprague-Dawley rat Environ. Int. 146 2021 106204 10.1016/j.envint.2020.106204
162 Blake B.E. Cope H.A. Hall S.M. Keys R.D. Mahler B.W. McCord J. Evaluation of maternal, embryo, and placental effects in CD-1 mice following gestational exposure to perfluorooctanoic acid (PFOA) or hexafluoropropylene oxide dimer acid (HFPO-DA or GenX) Environ. Health Perspect. 128 2020 27006 10.1289/EHP6233
163 Shi G. Cui Q. Pan Y. Sheng N. Sun S. Guo Y. 6: 2 Chlorinated polyfluorinated ether sulfonate, a PFOS alternative, induces embryotoxicity and disrupts cardiac development in zebrafish embryos Aquat. Toxicol. 185 2017 67 75 10.1016/j.aquatox.2017.02.002 28187362
164 Gaballah S. Swank A. Sobus J.R. Howey X.M. Schmid J. Catron T. Evaluation of developmental toxicity, developmental neurotoxicity, and tissue dose in zebrafish exposed to GenX and other PFAS Environ. Health Perspect. 128 2020 47005 10.1289/EHP5843
165 Fenton S.E. Ducatman A. Boobis A. DeWitt J.C. Lau C. Ng C. Per- and polyfluoroalkyl substance toxicity and human health review: current state of knowledge and strategies for informing future research Environ. Toxicol. Chem. 40 2021 606 630 10.1002/etc.4890 33017053
166 Guillette T.C. McCord J. Guillette M. Polera M.E. Rachels K.T. Morgeson C. Elevated levels of per- and polyfluoroalkyl substances in Cape Fear River Striped Bass (Morone saxatilis) are associated with biomarkers of altered immune and liver function Environ. Int. 136 2020 105358 10.1016/j.envint.2019.105358
167 Wang Z. Cousins I.T. Scheringer M. Hungerbuehler K. Hazard assessment of fluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors: status quo, ongoing challenges and possible solutions Environ. Int. 75 2015 172 179 10.1016/j.envint.2014.11.013 25461427
168 Scheringer M. Trier X. Cousins I.T. de Voogt P. Fletcher T. Wang Z. Helsingør statement on poly- and perfluorinated alkyl substances (PFASs) Chemosphere 114 2014 337 339 10.1016/j.chemosphere.2014.05.044 24938172
169 Hagstrom A.L. Anastas P. Boissevain A. Borrel A. Deziel N.C. Fenton S.E. Yale School of Public Health Symposium: an overview of the challenges and opportunities associated with per- and polyfluoroalkyl substances (PFAS) Sci. Total Environ. 778 2021 146192 10.1016/j.scitotenv.2021.146192
170 Bell E.M. De Guise S. McCutcheon J.R. Lei Y. Levin M. Li B. Exposure, health effects, sensing, and remediation of the emerging PFAS contaminants – scientific challenges and potential research directions Sci. Total Environ. 780 2021 146399 10.1016/j.scitotenv.2021.146399
171 Quist E.M. Filgo A.J. Cummings C.A. Kissling G.E. Hoenerhoff M.J. Fenton S.E. Hepatic mitochondrial alteration in CD-1 mice associated with prenatal exposures to low doses of perfluorooctanoic acid (PFOA) Toxicol. Pathol. 43 2015 546 557 10.1177/0192623314551841 25326589
172 Shabalina I.G. Kalinovich A.V. Cannon B. Nedergaard J. Metabolically inert perfluorinated fatty acids directly activate uncoupling protein 1 in brown-fat mitochondria Arch. Toxicol. 90 2016 1117 1128 10.1007/s00204-015-1535-4 26041126
173 Bijland S. Rensen P.C. Pieterman E.J. Maas A.C. van der Hoorn J.W. van Erk M.J. Perfluoroalkyl sulfonates cause alkyl chain length-dependent hepatic steatosis and hypolipidemia mainly by impairing lipoprotein production in APOE∗3-Leiden CETP mice Toxicol. Sci. 123 2011 290 303 10.1093/toxsci/kfr142 21705711
174 Bjork J.A. Butenhoff J.L. Wallace K.B. Multiplicity of nuclear receptor activation by PFOA and PFOS in primary human and rodent hepatocytes Toxicology 288 2011 8 17 10.1016/j.tox.2011.06.012 21723365
175 Rosen M.B. Das K.P. Rooney J. Abbott B. Lau C. Corton J.C. PPARα-independent transcriptional targets of perfluoroalkyl acids revealed by transcript profiling Toxicology 387 2017 95 107 10.1016/j.tox.2017.05.013 28558994
176 Li C.-H. Ren X.-M. Cao L.-Y. Qin W.-P. Guo L.-H. Investigation of binding and activity of perfluoroalkyl substances to the human peroxisome proliferator-activated receptor β/Δ Environ. Sci. Process. Impacts 21 2019 1908 1914 10.1039/c9em00218a 31332417
177 Kucharzyk K.H. Darlington R. Benotti M. Deeb R. Hawley E. Novel treatment technologies for PFAS compounds: a critical review J. Environ. Manag. 204 2017 757 764 10.1016/j.jenvman.2017.08.016
178 Dickenson E. Higgins C. Treatment Mitigation Strategies for Poly-and Perfluoroalkyl Substances, Water Research Foundation, Web report #4322 2016
179 Appleman T.D. Higgins C.P. Quiñones O. Vanderford B.J. Kolstad C. Zeigler-Holady J.C. Treatment of poly- and perfluoroalkyl substances in U.S. full-scale water treatment systems Water Res. 51 2014 246 255 10.1016/j.watres.2013.10.067 24275109
180 Xiao F. Simcik M.F. Gulliver J.S. Mechanisms for removal of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from drinking water by conventional and enhanced coagulation Water Res. 47 2013 49 56 10.1016/j.watres.2012.09.024 23123052
181 Bentel M.J. Yu Y. Xu L. Li Z. Wong B.M. Men Y. Defluorination of per- and polyfluoroalkyl substances (PFASs) with hydrated electrons: structural dependence and implications to PFAS remediation and management Environ. Sci. Technol. 53 2019 3718 3728 10.1021/acs.est.8b06648 30874441
182 Wang Y. Shi H. Li C. Huang Q. Electrochemical degradation of perfluoroalkyl acids by titanium suboxide anodes Environ. Sci.: Water Res. Technol. 6 2020 144 152 10.1039/C9EW00759H
183 Murray C.C. Vatankhah H. McDonough C.A. Nickerson A. Hedtke T.T. Cath T.Y. Removal of per- and polyfluoroalkyl substances using super-fine powder activated carbon and ceramic membrane filtration J. Hazard. Mater. 366 2019 160 168 10.1016/j.jhazmat.2018.11.050 30522083
184 Park M. Wu S. Lopez I.J. Chang J.Y. Karanfil T. Snyder S.A. Adsorption of perfluoroalkyl substances (PFAS) in groundwater by granular activated carbons: roles of hydrophobicity of PFAS and carbon characteristics Water Res. 170 2020 115364 10.1016/j.watres.2019.115364
185 Schaefer C.E. Nguyen D. Ho P. Im J. LeBlanc A. Assessing rapid small-scale column tests for treatment of perfluoroalkyl acids by anion exchange resin Ind. Eng. Chem. Res. 58 2019 9701 9706 10.1021/acs.iecr.9b00858
186 Robey N.M. da Silva B.F. Annable M.D. Townsend T.G. Bowden J.A. Concentrating per- and polyfluoroalkyl substances (PFAS) in municipal solid waste landfill leachate using foam separation Environ. Sci. Technol. 54 2020 12550 12559 10.1021/acs.est.0c01266 32865409
187 Hao S. Choi Y.-J. Wu B. Higgins C.P. Deeb R. Strathmann T.J. Hydrothermal alkaline treatment for destruction of per- and polyfluoroalkyl substances in aqueous film-forming foam Environ. Sci. Technol. 55 2021 3283 3295 10.1021/acs.est.0c06906 33557522
188 Krause M.J. Thoma E. Sahle-Damesessie E. Crone B. Whitehill A. Shields E. Supercritical water oxidation as an innovative technology for PFAS destruction J. Environ. Eng. 148 2021 1 8 10.1061/(asce)ee.1943-7870.0001957
189 Pramanik B.K. Pramanik S.K. Suja F. A comparative study of coagulation, granular- and powdered-activated carbon for the removal of perfluorooctane sulfonate and perfluorooctanoate in drinking water treatment Environ. Technol. 36 2015 2610 2617 10.1080/09593330.2015.1040079 25860623
190 Franke V. Ullberg M. McCleaf P. Wålinder M. Köhler S.J. Ahrens L. The price of really clean water: combining nanofiltration with granular activated carbon and anion exchange resins for the removal of per- and polyfluoralkyl substances (PFASs) in drinking water production ACS EST Water 1 2021 782 795 10.1021/acsestwater.0c00141
191 McCleaf P. Englund S. Östlund A. Lindegren K. Wiberg K. Ahrens L. Removal efficiency of multiple poly- and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests Water Res. 120 2017 77 87 10.1016/j.watres.2017.04.057 28478297
192 Sukeesan S. Boontanon S.K. Boontanon N. Fujii S. Regeneration of ion-exchange resins and granular activated carbon with the sonochemical technique for enabling adsorption of aqueous per- and polyfluoroalkyl substances IOP Conf. Ser. Earth Environ. Sci. 973 2022 012004 10.1088/1755-1315/973/1/012004
193 Belkouteb N. Franke V. McCleaf P. Köhler S. Ahrens L. Removal of per- and polyfluoroalkyl substances (PFASs) in a full-scale drinking water treatment plant: long-term performance of granular activated carbon (GAC) and influence of flow-rate Water Res. 182 2020 115913 10.1016/j.watres.2020.115913
194 Murray C.C. Marshall R.E. Liu C.J. Vatankhah H. Bellona C.L. PFAS treatment with granular activated carbon and ion exchange resin: comparing chain length, empty bed contact time, and cost J. Water Process Eng. 44 2021 102342 10.1016/j.jwpe.2021.102342
195 Dai X. Xie Z. Dorian B. Gray S. Zhang J. Comparative study of PFAS treatment by UV, UV/ozone, and fractionations with air and ozonated air Environ. Sci. Water Res. Technol. 5 2019 1897 1907 10.1039/C9EW00701F
196 Stebel E.K. Pike K.A. Nguyen H. Hartmann H.A. Klonowski M.J. Lawrence M.G. Absorption of short-chain to long-chain perfluoroalkyl substances using swellable organically modified silica Environ. Sci. Water Res. Technol. 5 2019 1854 1866 10.1039/C9EW00364A
197 Ateia M. Arifuzzaman M. Pellizzeri S. Attia M.F. Tharayil N. Anker J.N. Cationic polymer for selective removal of GenX and short-chain PFAS from surface waters and wastewaters at ng/L levels Water Res. 163 2019 114874 10.1016/j.watres.2019.114874
198 Olimattel K. Zhai L. Sadmani A.H.M.A. Enhanced removal of perfluorooctane sulfonic acid and perfluorooctanoic acid via polyelectrolyte functionalized ultrafiltration membrane: effects of membrane modification and water matrix J. Hazard. Mater. Lett. 2 2021 100043 10.1016/j.hazl.2021.100043
199 Boonya-Atichart A. Boontanon S.K. Boontanon N. Study of hybrid membrane filtration and photocatalysis for removal of perfluorooctanoic acid (PFOA) in groundwater Water Sci. Technol. 2017 2018 561 569 10.2166/wst.2018.178 29851409
200 Pica N.E. Funkhouser J. Yin Y. Zhang Z. Ceres D.M. Tong T. Electrochemical oxidation of hexafluoropropylene oxide dimer acid (GenX): mechanistic insights and efficient treatment train with nanofiltration Environ. Sci. Technol. 53 2019 12602 12609 10.1021/acs.est.9b03171 31599577
201 Chen X. Vanangamudi A. Wang J. Jegatheesan J. Mishra V. Sharma R. Direct contact membrane distillation for effective concentration of perfluoroalkyl substances – impact of surface fouling and material stability Water Res. 182 2020 116010 10.1016/j.watres.2020.116010
202 Liu Y.-L. Sun M. Ion exchange removal and resin regeneration to treat per- and polyfluoroalkyl ether acids and other emerging PFAS in drinking water Water Res. 207 2021 117781 10.1016/j.watres.2021.117781
203 Yu Q. Zhang R. Deng S. Huang J. Yu G. Sorption of perfluorooctane sulfonate and perfluorooctanoate on activated carbons and resin: kinetic and isotherm study Water Res. 43 2009 1150 1158 10.1016/j.watres.2008.12.001 19095279
204 Wang R. Ching C. Dichtel W.R. Helbling D.E. Evaluating the removal of per- and polyfluoroalkyl substances from contaminated groundwater with different adsorbents using a suspect screening approach Environ. Sci. Technol. Lett. 7 2020 954 960 10.1021/acs.estlett.0c00736
205 Olatunde O.C. Kuvarega A.T. Onwudiwe D.C. Photo enhanced degradation of polyfluoroalkyl and perfluoroalkyl substances Heliyon 6 2020 e05614 10.1016/j.heliyon.2020.e05614
206 Xu T. Zhu Y. Duan J. Xia Y. Tong T. Zhang L. Enhanced photocatalytic degradation of perfluorooctanoic acid using carbon-modified bismuth phosphate composite: effectiveness, material synergy and roles of carbon Chem. Eng. J. 395 2020 124991 10.1016/j.cej.2020.124991
207 Dalahmeh S.S. Alziq N. Ahrens L. Potential of biochar filters for onsite wastewater treatment: effects of active and inactive biofilms on adsorption of per- and polyfluoroalkyl substances in laboratory column experiments Environ. Pollut. 247 2019 155 164 10.1016/j.envpol.2019.01.032 30669083
208 Cornelsen M. Weber R. Panglisch S. Minimizing the environmental impact of PFAS by using specialized coagulants for the treatment of PFAS polluted waters and for the decontamination of firefighting equipment Emerg. Contam. 7 2021 63 76 10.1016/j.emcon.2021.02.001
209 Liu Z. Chen Z. Gao J. Yu Y. Men Y. Gu C. Accelerated degradation of perfluorosulfonates and perfluorocarboxylates by UV/sulfite + iodide: reaction mechanisms and system efficiencies Environ. Sci. Technol. 56 2022 3699 3709 10.1021/acs.est.1c07608 35226468
210 Trang B. Li Y. Xue X.-S. Ateia M. Houk K.N. Dichtel W.R. Low-temperature mineralization of perfluorocarboxylic acids Science 377 2022 839 845 10.1126/science.abm8868 35981038
211 Liu F. Guan X. Xiao F. Photodegradation of per- and polyfluoroalkyl substances in water: a review of fundamentals and applications J. Hazard. Mater. 439 2022 129580 10.1016/j.jhazmat.2022.129580
212 Boo C. Wang Y. Zucker I. Choo Y. Osuji C.O. Elimelech M. High performance nanofiltration membrane for effective removal of perfluoroalkyl substances at high water recovery Environ. Sci. Technol. 52 2018 7279 7288 10.1021/acs.est.8b01040 29851340
213 Nian M. Luo K. Luo F. Aimuzi R. Huo X. Chen Q. Association between prenatal exposure to PFAS and fetal sex hormones: are the short-chain PFAS safer? Environ. Sci. Technol. 54 2020 8291 8299 10.1021/acs.est.0c02444 32525661
214 Cordner A. Goldenman G. Birnbaum L.S. Brown P. Miller M.F. Mueller R. The true cost of PFAS and the benefits of acting now Environ. Sci. Technol. 55 2021 9630 9633 10.1021/acs.est.1c03565 34231362
215 Khera R. Ransom P. Speth T.F. Using work breakdown structure models to develop unit treatment costs Am. Water Works Assoc. 105 2013 E628 E641 10.5942/jawwa.2013.105.0129
216 Khera R. Ransom P. Guttridge M. Speth T.F. Estimating costs for nitrate and perchlorate treatment for small drinking water systems AWWA Water Sci. 3 2021 e1224 10.1002/aws2.1224
217 Moeini M. Modaresahmadi K. Tran T. Reddy K.R. Sustainability assessment of PFAS adsorbents for groundwater remediation Mater. Today Proc. 60 2022 2209 2216 10.1016/j.matpr.2022.03.014
218 Ellis A.C. Boyer T.H. Fang Y. Liu C.J. Strathmann T.J. Life cycle assessment and life cycle cost analysis of anion exchange and granular activated carbon systems for remediation of groundwater contaminated by per- and polyfluoroalkyl substances (PFASs) Water Res. 243 2023 120324 10.1016/j.watres.2023.120324
219 Amen R. Ibrahim A. Shafqat W. Hassan E.B. A critical review on PFAS removal from water: removal mechanism and future challenges Sustainability 15 2023 16173 10.3390/su152316173
220 Kanchanapiya P. Tantisattayakul T. Analysis of the additional cost of addressing per- and polyfluoroalkyl substance contamination from landfill leachate by reverse osmosis membranes in Thailand J. Water Process Eng. 45 2022 102520 10.1016/j.jwpe.2021.102520
221 Leonello D. Fendrich M.A. Parrino F. Patel N. Orlandi M. Miotello A. Light-induced advanced oxidation processes as PFAS remediation methods: a review Appl. Sci. 11 2021 8458 10.3390/app11188458
