Perfluoroalkyl Acids in Great Lakes Precipitation and Surface Water (2006-2018) Indicate Response to Phase-outs, Regulatory Action, and Variability in Fate and Transport Processes

Considerations and challenges in support of science and communication of fish consumption advisories for per- and polyfluoroalkyl substances

Federal, state, tribal, or local entities in the United States issue fish consumption advisories (FCAs) as guidance for safer consumption of locally caught fish containing contaminants. Fish consumption advisories have been developed for commonly detected compounds such as mercury and polychlorinated biphenyls. The existing national guidance does not specifically address the unique challenges associated with bioaccumulation and consumption risk related to per- and polyfluoroalkyl substances (PFAS). As a result, several states have derived their own PFAS-related consumption guidelines, many of which focus on one frequently detected PFAS, known as perfluorooctane sulfonic acid (PFOS). However, there can be significant variation between tissue concentrations or trigger concentrations (TCs) of PFOS that support the individual state-issued FCAs. This variation in TCs can create challenges for risk assessors and risk communicators in their efforts to protect public health. The objective of this article is to review existing challenges, knowledge gaps, and needs related to issuing PFAS-related FCAs and to provide key considerations for the development of protective fish consumption guidance. The current state of the science and variability in FCA derivation, considerations for sampling and analytical methodologies, risk management, risk communication, and policy challenges are discussed. How to best address PFAS mixtures in the development of FCAs, in risk assessment, and establishment of effect thresholds remains a major challenge, as well as a source of uncertainty and scrutiny. This includes developments better elucidating toxicity factors, exposures to PFAS mixtures, community fish consumption behaviors, and evolving technology and analytical instrumentation, methods, and the associated detection limits. Given the evolving science and public interests informing PFAS-related FCAs, continued review and revision of FCA approaches and best practices are vital. Nonetheless, consistent, widely applicable, PFAS-specific approaches informing methods, critical concentration thresholds, and priority compounds may assist practitioners in PFAS-related FCA development and possibly reduce variability between states and jurisdictions. Integr Environ Assess Manag 2024;20:1839-1858. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Storms mobilize organophosphate esters, bisphenols, PFASs, and vehicle-derived contaminants to San Francisco Bay watersheds

In urban to peri-urban watersheds such as those surrounding San Francisco Bay, stormwater runoff is a major pathway by which contaminants enter aquatic ecosystems. We evaluated the occurrence of 154 organic contaminants via liquid chromatography coupled to tandem mass spectrometry, including organophosphate esters (OPEs), bisphenols, per- and polyfluoroalkyl substances (PFASs), and a suite of novel urban stormwater tracers (SWCECs; i.e., vehicle-derived chemicals, pesticides, pharmaceuticals/personal care products, benzothiazoles/benzotriazoles). Time-averaged composite sampling focused on storms in highly developed watersheds over four wet seasons, with complementary sampling in less-urban reference watersheds, near-shore estuarine sites, and the open Bay. Of the targeted contaminants, 68 (21 SWCECs, 29 OPEs, 3 bisphenols, 15 PFASs) were detected in ≥10 of 26 urban stormwater samples. Median concentrations exceeded 500 ng L-1 for 1,3-diphenylguanidine, hexa(methoxymethyl)melamine, and caffeine, and exceeded 300 ng L-1 for 2-hydroxy-benzothiazole, 5-methyl-1H-benzotriazole, pentachlorophenol, and tris(2-butoxyethyl) phosphate. Median individual PFAS concentrations were <10 ng L-1, with highest concentrations for PFHxA (180 ng L-1), PFOA (110 ng L-1), and PFOS (81 ng L-1). In six of eight urban stormwater samples analyzed for 6PPD-quinone (a tire rubber-derived transformation product), concentrations exceeded coho salmon acute toxicity thresholds, suggesting (sub)lethal impacts for sensitive species. Observed concentrations were generally significantly higher in highly developed watersheds relative to reference watersheds, but not statistically different in near-shore estuarine sites, suggesting substantial transient exposure potential at stormwater outfalls or creek outflows. Results emphasized the role of stormwater in contaminant transport, the importance of vehicles/roadways as contaminant sources, and the value of monitoring broad multi-analyte contaminant suites to enable comprehensive source and toxicity evaluations.

Tissue-specific distribution and fatty acid content of PFAS in the northern Bohai Sea fish: Risk-benefit assessment of legacy PFAS and emerging alternatives

This study aimed to examine the distribution of poly- and perfluoroalkyl substances (PFAS) in 15 marine fish species from the northern Bohai Sea, investigate their sources of contamination, and evaluate the benefits-risks associated with the concurrent consumption of fish fatty acids and PFAS. The ∑PFAS concentrations in fish ranged from 9.38 to 262.92 ng·g-1 (dry weight). The highest PFAS levels were found in the viscera and gills, while the lowest levels were found in the muscles. Industrial effluents and sewage treatment plant discharges were the primary sources of PFAS contamination. The individual PFAS concentrations in fish were insignificantly correlated with their trophic levels (p > 0.05). However, the concentrations of hexafluoropropylene oxide dimer acid (HFPO-DA) or long-chain PFAS (C > 8) significantly increased with fish size (e.g., total length, weight) and lipid content (p < 0.001). The benefit-risk analysis suggests that HPFO-DA poses a higher health risk than perfluorooctanoic acid (PFOA) in fish (p < 0.05). Long-term consumption of contaminated fish may significantly increase human serum PFOA concentration and kidney cancer risk (p < 0.05). Daily consumption of 5 g (wet weight) muscle from Ditrema temmincki and Konosirus punctatus is recommended to meet the requirements for fatty acid supplementation without posing health risks.

Understanding the role of atmospheric deposition on the environmental load of per- and polyfluoroalkyl substances: A case study in Three Gorges Reservoir, China

Sixty-nine total suspended particle (TSP) samples, paired with forty-eight surface soil samples, covering four seasons from January 2021 to November 2021, were collected from the Three Gorges Reservoir Region (TGRR). Twenty per- and poly-fluoroalkyl substances (PFASs) were analyzed to evaluate their contamination characteristics and understand the role of atmospheric deposition on the environmental loads in TGRR. The annual average concentrations of PFASs in TSP and soil were 37.2 ± 1.22 pg·m-3 and 0.798 ± 0.134 ng·g-1, respectively. For TSP, concentrations were highest in spring and lowest in summer. For soil, it was in autumn and winter, respectively. The seasonality was more influenced by anthropogenic activities than by meteorological conditions or physicochemical parameters of the soil. Positive matrix fractionation (PMF) indicated that, based on annual averages, PFOA-based products (40.2 %) were the major sources of PFASs in TSP, followed by PFOS-based products (25.2 %) and precursor degradation (34.6 %). The highest source contributor for PFASs in spring was precursor degradation (40.9 %), while in other three seasons, it was PFOA-based products (39.9 %, 40.9 % and 52.0 %, respectively). The mean atmospheric dry and wet deposition fluxes of PFASs were estimated at 4.38 ng·m-2·day-1 and 23.5 ng·m-2·day-1, respectively. The contribution of atmospheric deposition to the inventory mass of PFASs in the surface soil was 22.3 %. These findings fill a gap in knowledge regarding the processes and mechanisms of the occurrence, sources and atmospheric deposition of PFASs in the TGRR.

The Ins and Outs of Per- and Polyfluoroalkyl Substances in the Great Lakes: The Role of Atmospheric Deposition

As part of the Integrated Atmospheric Deposition Network, precipitation (n = 207) and air (n = 60) from five sites and water samples (n = 87) from all five Great Lakes were collected in 2021-2023 and analyzed for 41 per- and polyfluoroalkyl substances (PFAS). These measurements were combined with other available data to estimate the mass budget for four representative compounds, PFBA, PFBS, PFOS, and PFOA for the basin. The median Σ41PFAS concentrations in precipitation across the five sites ranged between 2.4 and 4.5 ng/L. The median Σ41PFAS concentration in lake water was highest in Lake Ontario (11 ng/L) and lowest in Lake Superior (1.3 ng/L). The median Σ41PFAS concentration in air samples was highest in Cleveland at 410 pg/m3 and lowest at Sleeping Bear Dunes at 146 pg/m3. The net mass transfer flows were generally negative for Lakes Superior, Michigan, and Huron and positive for Lakes Erie and Ontario, indicating that the three most northern lakes are accumulating PFAS and the other two are eliminating PFAS. Atmospheric deposition is an important source of PFAS, particularly for Lake Superior.

Transport and health risk of legacy and emerging per-and polyfluoroalkyl substances in the water cycle in an urban area, China: Polyfluoroalkyl phosphate esters are of concern

Polyfluoroalkyl phosphate esters (PAPs) are a group of emerging alternatives to the legacy per- and polyfluoroalkyl substances (PFAS). To better understand the transport and risk of PAPs in the water cycle, 21 PFAS including 4 PAPs and 17 perfluoroalkyl acids were investigated in multiple waterbodies in an urban area, China. PFAS concentrations ranged from 85.8 to 206 ng/L, among which PAPs concentrations ranged from 35.0 to 71.8 ng/L, in river and lake water with major substances of perfluorooctanoic acid (PFOA), 6:2 fluorotelomer phosphate (6:2 monoPAP), and 8:2 fluorotelomer phosphate (8:2 monoPAP). As transport pathways, municipal wastewater and precipitation were investigated for PFAS mass loading estimation, and PAPs transported via precipitation more than municipal wastewater discharge. Concentrations of PFAS in tap water and raw source water were compared, and PAPs cannot be removed by drinking water treatment. In tap water, PFAS concentrations ranged from 132 to 271 ng/L and among them PAPs concentrations ranged from 41.6 to 61.9 ng/L. Human exposure and health risk to PFAS via drinking water were assessed, and relatively stronger health risks were induced from PFOS, PAPs, and PFOA. The environmental contamination and health risk of PAPs are of concern, and management implications regarding their sources, exposure, and hazards were raised.

Occurrence, bioaccumulation and trophic dynamics of per- and polyfluoroalkyl substances in two tropical freshwater lakes

We have investigated the occurrence, distribution, and biomagnification of per- and polyfluoroalkyl substances (PFAS) in two tropical lakes (Asejire and Eleyele) of Southwestern Nigeria, with contrasting urban intensities. Over an 8-month period, we sampled sediment and fish species (Clarias gariepinus: CIG; Oreochromis niloticus: ON; Coptodon guineensis: CG; Sarotherodon melanotheron: SM) across trophic levels, and analyzed various PFAS congeners, in addition to a select group of toxicological responses. While herbivores (SM) and benthic omnivores (CIG) at Asejire exhibited elevated levels of PFBS and PFOS, the pelagic omnivores (ON) showed a dominance of PFOS, PFDA, PFHxDA and EtFOSE in the muscle. At the Eleyele urban lake, PFAS patterns was dominated by PFBS, EtFOSE, PFPeS, PFOcDA and PFOS in the herbivores (SM, CG), EtFOSE, PFOS and PFBS in the pelagic omnivore (ON) and benthic omnivore (ClG). The estimated biomagnification factor (BMF) analysis for both lakes indicated trophic level increase of PFOS, PFUnA and PFDA at the suburban lake, while PFOS and EtFOSE biomagnified at the urban lake. We detected the occurrence of diSAMPAP and 9CL-PF3ONS, novel compounds not commonly reported, in PFAS studies at both lakes. The studied toxicological responses varied across trophic groups in both lakes with probable modulations by environmental conditions, trophic structure, and relative PFAS exposures in the lakes. The present study documents, for the first time in Nigeria, or any other African country, the role of urbanization on contaminant load into the environment and their implications for contaminant dynamics within the ecosystem and for aquatic food safety.

Uptake and distribution of perfluoroalkyl substances by grafted tomato plants cultivated in a contaminated site in northern Italy

Poly- and perfluoroalkyl substances (PFAS) are highly persistent and mobile pollutants raising alarming concerns due to their capability to accumulate in living organisms and exert toxic effects on human health. We studied the accumulation of different PFAS in the leaves and fruits of tomato plants grown on a PFAS-polluted soil in North-East Italy. Tomato plants were grafted with different rootstocks characterized by different vigor, and irrigated with PFAS-polluted groundwater. Leaves and fruits of the first and sixth truss were analyzed at full plant maturity. All tomato varieties accumulated PFAS in leaves and fruits, with the highest concentrations detected in the most vigorous rootstock and reflecting the PFAS concentration profile of the irrigation water. PFAS with a chain length from 4 to 8 C atoms and with carboxylic and sulfonic functional groups were detected in plant leaves, whereas only carboxylic C4, C5, and C6 PFAS were detected in tomato fruits. A general trend of decreasing PFAS concentrations in fruits upon increasing height of the plant trusses was observed. Calculation of the target hazard quotient (THQ) showed increasing values depending on the plant vigor. The hazard index (HI) values showed values slightly higher than 1 for the most vigorous plants, indicating potential risks to human health associated with the consumption of contaminated tomato fruits.

Characterizing the Movement of Per- and Polyfluoroalkyl Substances in an Avian Aquatic-Terrestrial Food Web

The movement of per- and polyfluoroalkyl substances (PFAS) through linked aquatic-terrestrial food webs is not well understood. Tree swallows (Tachycineta bicolor) in such systems may be exposed to PFAS from multiple abiotic and/or biotic compartments. We show from fatty acid signatures and carbon stable isotopes that tree swallow nestlings in southwestern Ontario fed on both terrestrial and aquatic macroinvertebrates. The PFAS profiles of air, terrestrial invertebrates, and swallows were dominated by perfluorooctanesulfonic acid (PFOS). Short-chain perfluoroalkyl acids (PFAAs) were largely restricted to air, surface water, and sediment, and long-chain PFAAs were mainly found in aquatic invertebrates and tree swallows. PFOS, multiple long-chain perfluorocarboxylic acids [perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorotridecanoic acid (PFTrDA)] and perfluorooctane sulfonamide precursors were estimated to bioaccumulate from air to tree swallows. PFOS bioaccumulated from air to terrestrial invertebrates, and PFOS, PFDA, and perfluorooctane sulfonamidoacetic acids (FOSAAs) bioaccumulated from water to aquatic invertebrates. PFOS showed biomagnification from both terrestrial and aquatic invertebrates to tree swallows, and PFDA and FOSAAs were also biomagnified from aquatic invertebrates to tree swallows. The movement of PFAS through aquatic-terrestrial food webs appears congener- and compartment-specific, challenging the understanding of PFAS exposure routes for multiple species involved in these food webs.

Perfluorooctanoic acid induces transcriptomic alterations in second trimester human cytotrophoblasts

Poly- and perfluroroalkylated substances (PFAS) are a major class of surfactants used in industry applications and consumer products. Despite efforts to reduce the usage of PFAS due to their environmental persistence, compounds such as perfluorooctanoic acid (PFOA) are widely detected in human blood and tissue. Although growing evidence supports that prenatal exposures to PFOA and other PFAS are linked to adverse pregnancy outcomes, the target organs and pathways remain unclear. Recent investigations in mouse and human cell lines suggest that PFAS may impact the placenta and impair trophoblast function. In this study, we investigated the effects of PFOA on cytotoxicity and the transcriptome in cultured second trimester human cytotrophoblasts (CTBs). We show that PFOA significantly reduces viability and induces cell death at 24 h, in a concentration-dependent manner. At subcytotoxic concentrations, PFOA impacted expression of hundreds of genes, including several molecules (CRH, IFIT1, and TNFSF10) linked with lipid metabolism and innate immune response pathways. Furthermore, in silico analyses suggested that regulatory factors such as peroxisome proliferator-activated receptor-mediated pathways may be especially important in response to PFOA. In summary, this study provides evidence that PFOA alters primary human CTB viability and gene pathways that could contribute to placental dysfunction and disease.

Non-targeted identification and semi-quantitation of emerging per- and polyfluoroalkyl substances (PFAS) in US rainwater

High-resolution mass spectrometry was used to screen for emerging per- and polyfluorinated alkyl substances (PFAS) in precipitation samples collected in summer 2019 at seven sites in the United States. We previously quantified the concentration of ten PFAS in the rainwater samples using the method of isotopic dilution (Pike et al., 2021). Nine of these targeted analytes belonged to the U.S. Environmental Protection Agency Regional Screening Level list, herein referred to as EPA-monitored analytes. In this new work, we identify emerging PFAS compounds by liquid chromatography quadrupole time-of-flight mass spectrometry. Several emerging PFAS were detected across all samples, with the most prevalent compounds being C3-C8 hydrogen-substituted perfluorocarboxylic acids (H-PFCAs) and fluorotelomer carboxylic acids (FTCAs). Concentrations of emerging PFAS were in the 10-1000 ng L-1 range (approximately 1-2 orders of magnitude greater than EPA-monitored PFAS) at all sites except Wooster, OH, where concentrations were even higher, with a maximum estimated ΣPFAS of 16 400 ng L-1. The elevated levels of emerging PFAS in the Wooster samples were predominantly even and odd chain-length H-PFCAs and FTCAs comprised of complex mixtures of branched isomers. This unique composition did not match any known manufactured PFAS formulation reported to date, but it could represent thermally transformed by-products emitted by a local point source. Overall, the results indicate that PFAS outside of the standard analyte lists make up a significant and previously unappreciated fraction of contaminants in rainwater collected within the central U.S.-and potentially world-wide-especially in proximity to localized point sources.

Temporal Trends of Legacy and Current-Use Halogenated Flame Retardants in Lake Ontario in Relation to Atmospheric Loadings, Sources, and Environmental Fate

Since the phase-out of polybrominated diphenyl ethers (PBDEs), large amounts of alternative halogenated flame retardants (AHFRs) have been introduced to the market. Due to their persistence and toxicity, halogenated flame retardants (HFRs) have become a concern for the ecosystem and human health. However, there remains limited assessment of the atmospheric loadings, sources, and environmental fate of HFRs in Lake Ontario, which receives urban-related inputs and cumulative chemical inputs from the upstream Great Lakes from Canada and the United States. We combined long-term measurements with a modified multimedia model based on site-specific environmental parameters from Lake Ontario to understand the trends and fate of HFRs. All HFRs were detected in the air, precipitation, lake trout, and herring gull egg samples throughout the sampling periods. General decreasing trends were found for PBDEs, while the temporal trends for AHFRs were not clear. Physical-chemical properties and emissions significantly influence the levels, profiles, and trends. Using the probabilistic modeling, HFR concentrations in lake water and sediment were predicted to be close to the measurement, suggesting a good performance for the modified model. The loadings from tributaries and wastewater effluent were the primary input pathways. Transformations in the water and sedimentation were estimated to be the dominant output pathway for the three HFRs.

Environmental Fate of Cl-PFPECAs: Accumulation of Novel and Legacy Perfluoroalkyl Compounds in Real-World Vegetation and Subsoils

Per- and polyfluoroalkyl substances (PFAS) are globally distributed and potentially toxic compounds. We report accumulation of chloroperfluoropolyethercarboxylates (Cl-PFPECAs) and perfluorocarboxylates (PFCAs) in vegetation and subsoils in New Jersey. Lower molecular weight Cl-PFPECAs, containing 7-10 fluorinated carbons, and PFCAs containing 3-6 fluorinated carbons were enriched in vegetation relative to surface soils. Subsoils were dominated by lower molecular weight Cl-PFPECAs, a divergence from surface soils. Contrastingly, PFCA homologue profiles in subsoils were similar to surface soils, likely reflecting temporal-use patterns. Accumulation factors (AFs) for vegetation and subsoils decreased with increasing CF2, 6-13 for vegetation and 8-13 in subsoils. In vegetation, for PFCAs having CF2 = 3-6, AFs diminished with increasing CF2 as a more sensitive function than for longer chains. Considering that PFAS manufacturing has transitioned from long-chain chemistry to short-chain, this elevated vegetative accumulation of short-chain PFAS suggests the potential for unanticipated PFAS exposure levels globally in human and/or wildlife populations. This inverse relationship between AFs and CF2-count in terrestrial vegetation is opposite the positive relationship reported in aquatic vegetation suggesting aquatic food webs may be preferentially enriched in long-chain PFAS. AFs normalized to soil-water concentrations increased with chain length for CF2 = 6-13 in vegetation but remained inversely related to chain length for CF2 = 3-6, reflecting a fundamental change in vegetation affinity for short chains compared to long.

Residue Distribution and Daily Exposure of Per- and Polyfluoroalkyl Substances in Indica and Japonica Rice

Per- and polyfluoroalkyl substances (PFAS) have excellent chemical stability but have adverse environmental impacts of concern. Furthermore, bioaccumulation of PFAS in rice varieties─which is the essential staple food crop in Asia─has not been verified. Therefore, we cultivated Indica (Kasalath) and Japonica rice (Koshihikari) in the same Andosol (volcanic ash soil) paddy field and analyzed the air, rainwater, irrigated water, soil, and rice plants for 32 PFAS residues, throughout the cultivation to human consumption. During the rice cultivation period, the cultivation environment in atmospheric particulate matter (PM) constituted perfluoroalkyl carboxylic acids (PFCAs), with minimal perfluorinated sulfonic acids (PFSAs). Furthermore, perfluorooctanesulfonic acid (PFOS) migrates at a PM > 10 to drop in a cultivation field and was conducive to leakage and accumulation of PFCAs in air particles in the field environment. Moreover, precipitation was a sources of irrigation water contamination, and cultivated soil with a high carbon content could capture PFSAs and PFCAs (over C₁₀). There were no major differences in residual PFAS trends in the rice varieties, but the distribution of PFAS in the growing soil, air, and rainwater differed. The edible white rice part was mainly affected by irrigation water in both varieties. Monte Carlo simulations of daily exposure assessments of PFOS, PFOA, and perfluorononanic acid showed similar results for Indians consuming Indica rice and Japanese consuming Japonica rice. The results indicate that the ultratrace PFAS residue concentrations and their daily exposure were not cultivar-specific.

Fractionation of perfluoroalkyl acids (PFAAs) along the aquatic food chain promoted by competitive effects between longer and shorter chain PFAAs

Perfluoroalkyl acids (PFAAs) are proteinophilic pollutants. We hypothesized that fractionation of PFAAs may occur along a food chain. To testify this hypothesis, we investigated the bioconcentration, bioaccumulation, and fractionation of 11 kinds of PFAAs (C-F = 3-11) along an aquatic food chain consisting of D. magna, zebrafish, and cichlid. The results showed that the proportions of PFNA, PFOA, and all shorter chain PFAAs in the D. magna and fish tissues were lower than the ones in exposure water, opposing to the other longer chain PFAAs. Predation promoted such fractionation differences, and the proportions of PFNA, PFOA, and all shorter chain PFAAs in organisms decreased while those of the other longer chain PFAAs increased along the food chain. The results of isothermal titration calorimetry and molecular docking experiments showed that binding affinities of PFAAs and fish proteins increased with the number of perfluorinated carbons, resulting in a substitution of shorter chain PFAAs by their longer chain analogues. It also triggered the differences in the uptake and elimination of PFFAs and competitive bioaccumulation between longer and shorter chain PFAAs. This study suggests that fractionation should be considered in studying environmental behaviors and evaluating ecological risks of multiple PFAAs.

Impacts of Environmental and Engineered Processes on the PFAS Fingerprint of Fluorotelomer-Based AFFF

Forensic analysis can potentially be used to determine per- and polyfluoroalkyl substance (PFAS) sources at contaminated sites. However, fluorotelomer aqueous film-forming foam (AFFF) sources are difficult to identify because the polyfluorinated active ingredients do not have authentic standards and because the parent compounds can undergo transformation and differential transport, resulting in alteration of the PFAS distribution or fingerprint. In this study, we investigate changes in the PFAS fingerprint of fluorotelomer-derived AFFF due to environmental and engineered processes, including groundwater transport, surface water flow, and land application of contaminated biosolids. Fingerprint analysis supplemented by quantification of precursors and identification of suspected active ingredients shows a clear correlation between a fluorotelomer AFFF manufacturer and surface water of nearby Lake Michigan, demonstrating contamination (>100 ng/L PFOA) of the lake due to migration of an AFFF-impacted groundwater plume. In contrast, extensive processing during wastewater treatment and environmental transport results in large changes to the AFFF fingerprint near agricultural fields where contaminated biosolids were spread. At biosolids-impacted sites, the presence of active ingredients confirms contamination by fluorotelomer AFFF. While sediments can retain longer-chain PFAS, this study demonstrates that aqueous samples are most relevant for PFAS fingerprinting in complex sites, particularly where shorter-chain compounds have been used.

Bioaccumulation and trophic magnification of emerging and legacy per- and polyfluoroalkyl substances (PFAS) in a St. Lawrence River food web

Research on per- and polyfluoroalkyl substances (PFAS) in freshwater ecosystems has focused primarily on legacy compounds and little is still known on the presence of emerging PFAS. Here, we investigated the occurrence of 60 anionic, zwitterionic, and cationic PFAS in a food web of the St. Lawrence River (Quebec, Canada) near a major metropolitan area. Water, sediments, aquatic vegetation, invertebrates, and 14 fish species were targeted for analysis. Levels of perfluorobutanoic acid (PFBA) in river water exceeded those of perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS), and a zwitterionic betaine was observed for the first time in the St. Lawrence River. The highest mean PFAS concentrations were observed for the benthopelagic top predator Smallmouth bass (Micropterus dolomieu, Σ₆₀PFAS ∼ 92 ± 34 ng/g wet weight whole-body) and the lowest for aquatic plants (0.52-2.3 ng/g). Up to 33 PFAS were detected in biotic samples, with frequent occurrences of emerging PFAS such as perfluorobutane sulfonamide (FBSA) and perfluoroethyl cyclohexane sulfonate (PFECHS), while targeted ether-PFAS all remained undetected. PFOS and long-chain perfluorocarboxylates (C10-C13 PFCAs) dominated the contamination profiles in biota except for insects where PFBA was predominant. Gammarids, molluscs, and insects also had frequent detections of PFOA and fluorotelomer sulfonates, an important distinction with fish and presumably due to different metabolism. Based on bioaccumulation factors >5000 and trophic magnification factors >1, long-chain (C10-C13) PFCAs, PFOS, perfluorodecane sulfonate, and perfluorooctane sulfonamide qualified as very bioaccumulative and biomagnifying. Newly monitored PFAS such as FBSA and PFECHS were biomagnified but moderately bioaccumulative, while PFOA was biodiluted.

Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substances (PFAS)

It is hypothesized that environmental contamination by per- and polyfluoroalkyl substances (PFAS) defines a separate planetary boundary and that this boundary has been exceeded. This hypothesis is tested by comparing the levels of four selected perfluoroalkyl acids (PFAAs) (i.e., perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA)) in various global environmental media (i.e., rainwater, soils, and surface waters) with recently proposed guideline levels. On the basis of the four PFAAs considered, it is concluded that (1) levels of PFOA and PFOS in rainwater often greatly exceed US Environmental Protection Agency (EPA) Lifetime Drinking Water Health Advisory levels and the sum of the aforementioned four PFAAs (Σ4 PFAS) in rainwater is often above Danish drinking water limit values also based on Σ4 PFAS; (2) levels of PFOS in rainwater are often above Environmental Quality Standard for Inland European Union Surface Water; and (3) atmospheric deposition also leads to global soils being ubiquitously contaminated and to be often above proposed Dutch guideline values. It is, therefore, concluded that the global spread of these four PFAAs in the atmosphere has led to the planetary boundary for chemical pollution being exceeded. Levels of PFAAs in atmospheric deposition are especially poorly reversible because of the high persistence of PFAAs and their ability to continuously cycle in the hydrosphere, including on sea spray aerosols emitted from the oceans. Because of the poor reversibility of environmental exposure to PFAS and their associated effects, it is vitally important that PFAS uses and emissions are rapidly restricted.

Formation and fate of perfluoroalkyl acids (PFAAs) in a laboratory-scale urban wastewater system

The fate and formation of perfluoroalkyl acids (PFAAs) have been investigated during wastewater treatment processes but studies for the entire urban wastewater system comprising the sewage transport and wastewater and sludge treatment processes are scarce. This work performs an integrated assessment of the formation and fate of PFAAs in the urban wastewater system together with their behavior in separate components of the system. To achieve this, PFAAs were monitored over five weeks in a laboratory-scale urban wastewater system comprising sewer reactors, a wastewater treatment reactor, and an anaerobic sludge digester. The system was fed with real domestic wastewater. The total mass of 11 PFAAs flowing out of the laboratory wastewater system significantly (p < 0.05) increased by 112 ± 14 (mean ± standard error)% compared to that entering the system. Formation of PFAAs was observed in all three biological processes of the system. In anaerobic sewer process, perfluoropentanoic acid (PFPeA), perfluoroheptanoic acid (PFHpA), and perfluorooctane sulfonate (PFOS) exhibited significant formation (p < 0.05) with the mass flow increased by 79 ± 24%, 109 ± 31%, and 57 ± 17%, respectively. During the wastewater treatment process, perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorododecanoic acid (PFDoDA) demonstrated significant increase (p < 0.05) in their mass flows by 176 ± 56%, 92 ± 21%, and 516 ± 184%, respectively. In contrast, only PFHxA was found to significantly (p < 0.05) increase by 130 ± 40% during anaerobic digestion process. The total mass of 11 PFAAs discharged through the effluent (201 ± 24 ng day^-1) was 5 times higher than that through the digested sludge (29 ± 6 ng day^-1).

Perfluoroalkyl Substances (PFASs) in the Canadian Freshwater Environment

Per- and polyfluoroalkyl substances (PFASs) are anthropogenic substances that are very stable in the receiving environment. Legacy perfluoroalkane sulfonates (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs) are especially persistent and resistant to typical environmental degradation processes and therefore are distributed across all trophic levels and environmental compartments (soil, air, water). Since most uses of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and LC-long-chain PFCAs are banned in Canada, alternative PFASs have been in use for a number of years. Twenty-nine sites across Canada were sampled for PFASs to determine concentrations and trends. Overall, 13 PFASs were measured in 566 Canadian freshwater samples from 2013 to 2020 with a range from below the detection limit (LOD range: 0.4-1.6 ng/L) of the laboratory to a maximum of 138 ng/L (for PFBS). While PFOS and PFOA concentrations are declining significantly over time, other compounds such as PFPeA and PFBA have increased significantly over 2013-2020. Overall, the range of concentrations found in this study was similar to that of other Canadian and international studies. However, this study also found a higher frequency of detections of the replacement PFASs than that of the other, older, Canadian studies.

Legacy and Emerging Per- and Polyfluoroalkyl Substances Behave Distinctly in Spatial Distribution and Multimedia Partitioning: A Case Study in the Pearl River, China

Per- and polyfluoroalkyl substances (PFASs) have attracted worldwide attention due to their ubiquitous occurrence, bioaccumulation, and toxicological effects, yet the fate of PFASs in a lotic ecosystem is largely unknown. To elucidate spatial distribution and multimedia partitioning of legacy and emerging PFASs in a lotic river flowing into an estuary, PFASs were synchronously analyzed in water, suspended particulate matter (SPM), sediment, and biota samples collected along Guangzhou reach of the Pearl River, South China. Geographically, the concentrations of PFASs in the water phase showed a decreasing trend from the upper and middle sections (urban area) to the down section (suburban area close to estuary) of the river. While perfluorooctanoic acid predominated in water and SPM, more diverse compositions were observed in sediment and biota with the increase in contributions of long-chain PFASs. Field-derived sediment-water partitioning coefficients (K_d) and bioaccumulation factors (BAFs) of PFASs increased with the increase in perfluorinated carbons. Besides hydrophobicity, water pH and salinity significantly affected the multimedia partitioning of PFASs in a lotic ecosystem. In addition, 87 homologues (63 classes) were identified as emerging PFASs in four media using suspect analysis. Interestingly, K_d and BAF of the emerging PFASs were often higher than legacy PFASs containing the same perfluorinated carbons, raising a special concern on the environmental risk of emerging PFASs.

Mass Balance of Perfluoroalkyl Acids, Including Trifluoroacetic Acid, in a Freshwater Lake

Perfluoroalkyl acids (PFAAs) are highly persistent chemicals that are ubiquitously found in the environment. The atmospheric degradation of precursor compounds has been identified as a source of PFAAs and might be an important pathway for contamination. Lake Vättern is one of Sweden's largest lakes and is an important source for drinking water. In addition to contamination via atmospheric deposition, the lake is subject to several potential contamination sources via surface water inflow. The relevance of different sources is not well understood. A mass balance of selected PFAAs was assembled based on measured concentrations in atmospheric deposition, surface water from streams that constitute the main inflow and outflow, and surface water in the lake. The largest input was seen for trifluoroacetic acid (150 kg/year), perfluoropropanoic acid (1.6 kg/year), perfluorobutanoic acid (4.0 kg/year), and perfluoro-octanoic acid (1.5 kg/year). Both atmospheric deposition and surface water inflow was found to be important input pathways. There was a positive correlation between the input of most perfluoroalkyl carboxylic acids via atmospheric deposition and global radiation and between the input via surface water inflow and catchment area. These findings highlight the importance of atmospheric oxidation of volatile precursor compounds for contamination in surface waters.

Source apportionment of perfluoroalkyl substances in Great Lakes fish

Due to the complex sources and fate of perfluoroalkyl substance (PFAS), their source apportionment in the environment remains a challenge. A data set of 11 straight-chain PFAS in 139 samples of fish in the Great Lakes was analyzed using positive matrix factorization (PMF) to investigate their primary sources, whose spatial variations were examined against the surrounding environmental factors. PMF analysis produced five fingerprints. Factor 1 (72% of Σ₁₁PFAS, dominated by PFOS) probably represented emissions from primary sources (such as consumer products) and secondary sources (precursors), and increased in average abundance from west to east across the Great Lakes. Factor 2 (13% of Σ₁₁PFAS) and factor 3 (7% of Σ₁₁PFAS), highly loaded with long-chain PFAS and PFNA, respectively, were thought to represent PVDF manufacture or processing in metal plating. They showed higher contributions in sparsely populated Lakes Superior and Huron. Factor 4 (5% of Σ₁₁PFAS, highly loaded with PFOS and PFHxS) presented hot spots near current and former air force bases, suggesting it was related to aqueous film-forming foams (AFFFs). Factor 5 (4% of Σ₁₁PFAS) contained primarily PFOS and PFOSA, which may imply metabolism of precursors (PFOSA) to PFOS in vivo. Unexpectedly, the spatial trends of the five sources all showed abnormally low values near the more urbanized Chicago and Milwaukee in Lake Michigan, which may be due to their unique wastewater and stormwater infrastructure or may arise from atmospheric transport of precursors. Our study indicated that PMF was an effective tool to identify sources of PFAS in fish despite absorption, distribution, metabolism, and excretion (ADME) processes which might alter fingerprints in fish relative to their surrounding environment.

GenX is not always a better fluorinated organic compound than PFOA: A critical review on aqueous phase treatability by adsorption and its associated cost

Hexafluoropropylene oxide dimer acid (GenX) has been marketed as a substitute for perfluorooctanoic acid (PFOA) to reduce environmental and health risks. GenX and PFOA have been detected in various natural water sources, and adsorption is recognized as a typical treatment process for PFOA removal. In this paper, comparisons of GenX and PFOA adsorption are evaluated, including adsorption potential, adsorption mechanisms, and associated costs. A detailed literature review suggests that anion-exchange resins are more effective in removing GenX than activated carbon. GenX removal efficiency through activated carbon (30%) is lower than that of PFOA (80-95%), while GenX and PFOA removal efficiencies by anion exchange resins are similar (99%). Unconventional adsorbents, such as ionic fluorogels and covalent organic frameworks can effectively remove GenX from water. The review reveals that GenX adsorption is more challenging, requiring almost 4 times the treatment cost of its predecessor, PFOA. Annual operation and maintenance costs for GenX adsorption (initial concentration of GenX and PFOA = 0.2 µg.L^-1) by GAC for treating 10,000 m³ per day is almost US$1,000,000 per year, but only around US$240,000 per year for PFOA. Desorption of GenX in the presence of PFOA highlights GenX's inferior treatability by adsorption. It is believed that GenX is a more environmentally friendly compound than PFOA, but this environmental friendliness comes with the price.

Occurrence and transport of perfluoroalkyl acids (PFAAs) in a Yangtze River water diversion project during water diversion and flooding

Water diversion is increasingly utilized for water supply, flood control, irrigation, and water quality improvement in many water bodies globally. Our findings indicate that micropollutants such as perfluoroalkyl acids (PFAAs) can be transported via dual-source water diversion projects during water diversion and flood discharge, which may negatively impact both receiving water bodies. However, the sources, spatiotemporal variations, and fluxes of PFAAs under water diversion projects remain unclear. Here we report patterns of 18 PFAA compounds in the surface water at 14 sites of a dual-source water diversion project (Wangyu River) connecting the Yangtze River and Taihu Lake in China. We found multiple contamination hotspots with PFHxA and PFOA dominantly originating from industrial and domestic sources during water diversion from the Yangtze River to Taihu Lake. During the severe flooding in summer 2020, PFAA concentrations ranged from 82.0 to 114.0 ng L^-1, while the concentrations and relative contributions of individual perfluoroalkane sulfonic acids (PFSAs) increased along the mainstream due to the tributaries' contribution and high contamination level in the lake. Based on the spatiotemporal patterns of PFAA pollution, the flux of total PFAAs including both dissolved-phase and SS-phase into Taihu Lake was estimated as 26.6 kg in January 2020 as a reference value for water diversion. To our knowledge, this is the first report to describe the sources, occurrences, and transport of PFAAs in a dual-source water diversion project during water diversion and flooding. The results provide a novel perspective regarding the ecological safety of dual-source water diversion projects.

Heterogeneous photooxidation of 6:2 polyfluoroalkyl phosphoric acid diester on dust mineral components under simulated sunlight and the influence of relative humidity and oxygen

Polyfluoroalkyl phosphoric acid diesters (diPAPs) have been widely and increasingly detected in various environmental mediums. The degradation of diPAPs brings perfluoroalkyl carboxylic acids (PFCAs) concerned of adverse health effects. DiPAPs mainly occur in particulate matter in ambient air and their photo-degradation behaviors have not been investigated. In this study, heterogeneous photo-degradation of 6:2 diPAP was studied on four model mineral components in ambient dust. 6:2 diPAP was found to undergo a fast degradation on titanium dioxide (TiO₂) particles as well as on artificial mineral dust containing TiO₂ (2.67% in mass) to produce C5-C7 PFCAs and other intermediates. Based on monitored intermediates and further degradation tests on important intermediates, thermodynamic calculation of energy barrier and Gibbs Free Energy was used to explain the observed degradation patterns and accordingly the degradation pathways of diPAPs were proposed. The increase in relative humidity promotes the production of hydroxyl radicals, which enhances the hydrolysis of 6:2 mono- and di-PAPs and the yield of C5 and C7 PFCAs. Oxygen is critical for radical formation, which bypasses the production of fluorotelomer carboxylic acid. Results of this study for the first time demonstrate that diPAP may account for additional PFCA sources in both indoor and outdoor environments and the heterogeneous degradation pathways were different from those of volatile fluorotelomer alcohols.

Perfluoroalkyl substances (PFASs) in the Ugandan waters of Lake Victoria: Spatial distribution, catchment release and public exposure risk via municipal water consumption

Perfluoroalkyl substances (PFASs) have scarcely been studied in the Lake Victoria Basin and Africa in general. We investigated spatial profiles of PFASs in the Ugandan part of Lake Victoria, their influxes and human exposure via drinking water. We analyzed open lake water, riverine water (Rivers Kagera and Sio), urban drainage water (Nakivubo Channel), over-lake bulk atmospheric deposition and municipal tap water (Kampala, Jinja and Entebbe). The average concentrations (ng/L) for individual target PFASs were in the ranges of 0.08-23.8 (Nakivubo Channel), 0.01-10.8 (Murchison Bay), <MDL-5.38 (Kampala tap water), 0.01-3.64 (R. Kagera), <MDL-3.56 (Jinja tap water), <MDL-3.35 (R. Sio), <MDL-1.96 (Entebbe tap water), <MDL-1.46 (open lake) and <MDL-1.00 (atmospheric deposition). Estimated contribution of input pathways to ∑PFAS fluxes into Lake Victoria was in the order atmospheric deposition > R. Kagera, >R. Sio > Nakivubo Channel. Perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonic acid (PFOS) had the highest influx and retention estimates, respectively. Perfluoroalkane sulfonates (PFSAs) were mostly associated with urban drainage samples. PFASs were likely recycled from the Nakivubo Channel, through the Murchison Bay, into municipal drinking water. The estimated human exposure to ∑₁₁PFASs via drinking water indicated low risk of adverse health effects.

Spatial and Temporal Trends of Perfluoroalkyl Substances in Global Ocean and Coastal Waters

Per- and polyfluoroalkyl substances (PFAS) have been widely detected in global surface waters since the early 2000s. Here, we have compiled and analyzed the published data for perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) in surface waters of coastal seas, the Great Lakes, and open oceans to examine temporal and geospatial trends. Mass discharges from major rivers were also estimated. A large number of measurements of individual PFAS have been made in these surface waters (29 500 values), with seven C4-C10 PFSAs and nine C4-C12 PFCAs accounting for 83% of all data. However, most results (85% for PFSAs; 80% for PFCAs) were for the coastal seas of Western Europe, China, Korea, and Japan, while results were limited for coastal North America and lacking for South America and Africa. Highest median concentrations of PFCAs and PFSAs were reported in the Bohai and Yellow Seas region of China as well as in the North and Baltic seas in Europe. Significant declines in median PFSAs and C7-C12 PFCAs were also observed for the period 2012-2018 in these same regions, and for 2004-2017 in the Great Lakes. Mass discharge estimates indicated continued substantial riverine emissions of long chain (C7-C12) PFCAs in the period 2015-2019 for the coastal seas of China and reductions in emissions for Western European rivers compared to earlier time periods.

Trends (2005-2016) of perfluoroalkyl acids in top predator fish of the Laurentian Great Lakes

This work presents the first assessment of temporal trends (2005-2016) for perfluoroalkyl acids (PFAAs) in top predator fish of the Laurentian Great Lakes except Lake Ontario, for which we provide a post-2008 update. Lake trout (Salvelinus namaycush) or walleye (Sander vitreus; Lake Erie only) collected annually from 2005 to 2016 were analyzed for 12 perfluoroalkyl carboxylic acids (PFCAs) and 4 perfluoroalkyl sulfonic acids (PFSAs) with carbon chain lengths between 4 and 16 (C4-C16). Individual analyte concentrations generally decreased in fish basin-wide between 2005 and 2016, including Lake Ontario lake trout previously found to lack declining PFAA concentrations up until 2008. Declining fish PFAA burden reflects a positive response to the industrial phase-outs of these chemicals. Notable exceptions to this general decline included most analytes in lake trout collected from Lake Superior near Keweenaw Point and C6 and C8 PFSAs and C9 PFCAs in Lake Erie lake trout and walleye, which exhibited constant or increasing concentrations in recent years. Recent increases in Lake Superior shoreline development and mobilization from increased sediment resuspension and contamination from biosolids-amended agricultural soils in the Lake Erie watershed are plausible explanations for these cases. However, data scarcity prohibits confirmation of these suspected causes. The lingering lack of declining concentrations noted in this study together with the ongoing evolution of the fluorinated chemical industry emphasize the vigilance needed to better understand how past and future emissions will affect the Great Lakes and global ecosystems.

Fabrication of a near-infrared excitation surface molecular imprinting ratiometric fluorescent probe for sensitive and rapid detecting perfluorooctane sulfonate in complex matrix

Construction of fluorescent probe for highly sensitive and selective detection of perfluorooctane sulfonate (PFOS) in water and biological samples is a very important strategy in related pollutant monitoring and environmental health risk appraisal. To overcome the drawback of low sensitivity caused by high-back ground signal of the conventional sensor, a molecularly imprinted near-infrared excitation ratiometric fluorescent probe was constructed and employed to determine PFOS. The sensing process was achieved through the selectively recognition of specific cavities in the probe surface with analyte, accompanied by fluorescence quenching due to the photoinduced electron transfer effect between upconversion materials and PFOS. Under optimized experimental conditions, the fluorescence quenching efficiency of the probe has good linearity against the concentrations of PFOS response divided into two segments within linear ranges of 0.001-0.1 nmol/L and 0.1-1 nmol/L, respectively, with low detection limit of 1 pmol/L. Selective experiment results indicate that the C-F chain length plays a dominant role in molecular recognition and high sensitively detection. The fabricated probe shows well detection performance in a wide pH range. Furthermore, real samples analyses indicate that such an efficient fluorescent probe has potentials in PFOS determination in surface water, human serum and egg extract sample analyses.

Serum per- and polyfluoroalkyl substance (PFAS) concentrations and predictors of exposure among pregnant African American women in the Atlanta area, Georgia

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with adverse health outcomes, especially when exposure occurs within sensitive time windows such as the pre- and post-natal periods and early childhood. However, few studies have focused on PFAS exposure distribution and predictors in pregnant women, especially among African American women. We quantified serum concentrations of the four most common PFAS collected in all 453 participants and an additional 10 PFAS in 356 participants who were pregnant African American women enrolled from 2014 to 2018 in Atlanta, Georgia, and investigated the sociodemographic predictors of exposure. Additional home environment and behavior predictors were also examined in 130 participants. Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected in >95% of the samples with PFOS having the highest concentrations (geometric mean (GM) 2.03 ng/mL). N-Methyl perfluorooctane sulfonamido acetic acid (NMeFOSAA), perfluoropentanoic acid (PFPeA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) were found in 40-50% of the samples, whereas the detection frequencies for the other six PFAS were below 15%. When compared to National Health and Nutrition Examination Survey (NHANES) participants matching sex, race, and age with this study, our results showed similar concentrations of most PFAS, but higher concentrations of PFHxS (GM 0.99 ng/mL in this study; 0.63 and 0.4 ng/mL in NHANES, 2014-2015 and 2016-2017 cycles). A decline in concentrations over the study period was found for most PFAS but not PFPeA. In adjusted models, education, sampling year, parity, BMI, tobacco and marijuana use, age of house, drinking water source, and cosmetic use were significantly associated with serum PFAS concentrations. Our study reports the first PFAS exposure data among pregnant African American women in the Atlanta area, Georgia. The identified predictors will facilitate the setting of research priorities and enable development of exposure mitigation strategies.

Per- and Polyfluoroalkyl Substances (PFAS) in Breast Milk: Concerning Trends for Current-Use PFAS

This is the first study in the last 15 years to analyze per- and polyfluoroalkyl substances (PFAS) in breast milk collected from mothers (n = 50) in the United States, and our findings indicate that both legacy and current-use PFAS now contaminate breast milk, exposing nursing infants. Breast milk was analyzed for 39 PFAS, including 9 short-chain and 30 long-chain compounds, and 16 of these PFAS were detected in 4-100% of the samples. The ∑PFAS concentration in breast milk ranged from 52.0 to 1850 pg/mL with a median concentration of 121 pg/mL. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were the most abundant PFAS in these samples (medians 30.4 and 13.9 pg/mL, respectively). Two short-chain PFAS, including perfluoro-n-hexanoic acid (PFHxA, C6) and perfluoro-n-heptanoic acid (PFHpA, C7), were detected in most of the samples with median concentrations of 9.69 and 6.10 pg/mL, respectively. Analysis of the available breast milk PFAS data from around the world over the period of 1996-2019 showed that while the levels of the phased-out PFOS and PFOA have been declining with halving times of 8.1 and 17 years, respectively, the detection frequencies of current-use short-chain PFAS have been increasing with a doubling time of 4.1 years.

Organic contaminants of emerging concern in leachate of historic municipal landfills

Many types of contaminants of emerging concern (CECs), including per- and poly-fluoroalkyl substances (PFAS), have been found in leachate of operating municipal landfills. However, there is only limited information on CECs presence in leachate of historic landfills (≥3 decades since closure, often lacking engineered liners or leachate collection systems) at concentrations that may pose a risk to nearby wells and surface water ecosystems. In this study, 48 samples of leachate-impacted groundwater were collected from 20 historic landfills in Ontario, Canada. The CECs measured included artificial sweeteners (ASs), PFAS, organophosphate esters (OPE), pharmaceuticals, bisphenols, sulfamic acid, perchlorate, and substituted phenols. The common presence of the AS saccharin, a known indicator of old landfill leachate, combined with mostly negligible levels of the AS acesulfame, an indicator of modern wastewater, revealed that most samples were strongly influenced by leachate and not cross-contaminated by wastewater (which can contain these same CECs). Several landfills, including ones closed in the 1960s, had total PFAS concentrations similar to those previously measured at modern landfills, with a maximum observed here of 12.7 μg/L. Notably elevated concentrations of several OPE, sulfamic acid, cotinine, and bisphenols A and S were found at many 30-60 year-old landfills. There was little indication of declining concentrations with landfill age, suggesting historic landfills can be long-term sources of CECs to groundwater and that certain CECs may be useful tracers for historic landfill leachate. These findings provide guidance on which CECs may require monitoring at historic landfill sites and wastewater treatment plants receiving their effluent.

A Critical Review of a Recommended Analytical and Classification Approach for Organic Fluorinated Compounds with an Emphasis on Per- and Polyfluoroalkyl Substances

Organic fluorinated compounds have been detected in various environmental media and biota. Some of these compounds are regulated locally (e.g., perfluorononanoic acid maximum contaminant level in drinking water by the New Jersey Dept. of Environmental Protection), nationally (e.g., perfluorooctanoic acid maximum acceptable concentration in drinking water by Health Canada), or internationally (e.g., Stockholm Convention on Persistent Organic Pollutants). Globally, regulators and researchers seek to identify the organic fluorinated compounds associated with potential adverse effects, bioaccumulation, mobility, and persistence to manage their risks, and, to understand the beneficial attributes they bring to products such as first responder gear, etc. Clarity is needed to determine the best analytical method for the goal of the analyses (e.g., pure research or analysis to determine the extent of an accidental release, monitoring groundwater for specific compounds to determine regulatory compliance, and establish baseline levels in a river of organic fluorinated substances associated with human health risk prior to a clean-up effort). Analytical techniques that identify organic fluorine coupled together with targeted chemical analysis will yield information sufficient to identify public health or environmental hazards. Integr Environ Assess Manag 2021;17:331-351. © 2020. W.L. Gore & Associates Inc. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Correlation Analysis of Perfluoroalkyl Substances in Regional U.S. Precipitation Events

Per- and polyfluoroalkyl substances (PFAS) are transported in the atmosphere, leading to both wet and dry deposition to the surface. The concentrations of 15 PFAS were measured at six locations in the Ohio-Indiana region of the U.S. during the summer of 2019 and compared to samples collected at a distant site in NW Wyoming. ΣPFAS concentrations ranged from 50-850 ng L^-1, with trifluoroacetic acid (TFA) being the dominant compound (~90%). Concentrations of perfluorooctanoic acid (PFOA) and perfluorosulfonic acid (PFOS) were similar to amounts observed over the past 20 years, indicating persistence in the atmosphere despite regulatory action, and the newer species HFPO-DA (GenX) was also widely detected in rainwater. ANOVA modeling and correlation matrices were used to determine association of PFAS concentrations, location, and functional group and chain length. Statistically significant differences (p < 0.05) in PFAS profiles across sites separated by 10-100 km indicate that local point sources strongly contribute to wet deposition. This work introduces correlation plots for PFAS that allow rapid visual comparison of multi-analyte and multi-site data sets.

Lethal and sublethal toxicity of perfluorooctanoic acid (PFOA) in chronic tests with Hyalella azteca (amphipod) and early-life stage tests with Pimephales promelas (fathead minnow)

Perfluoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA), are industrial chemicals that are of concern due to their environmental presence, persistence, bioaccumulative potential, toxicity, and capacity for long-range transport. Despite a large body of research on environmental exposure, insufficient chronic aquatic toxicity data exist to develop water quality targets for clean-up of federal contaminated sites in Canada. Thus, our objective was to assess the aqueous toxicity of PFOA in chronic tests with Hyalella azteca (amphipod) and early-life stage tests with Pimephales promelas (fathead minnow). Toxicity data were analyzed based on measured PFOA concentrations. Amphipod exposures were 42 d (0.84-97 mg/L) and examined survival, growth, and reproduction. Fathead minnow exposures were 21 d (0.010-76 mg/L), which encompassed hatching (5 d) and larval stages until 16 d post-hatch; endpoints included hatching success, deformities at hatch, and larval survival and growth. Amphipod survival was significantly reduced at 97 mg/L (42-d LC50 = 51 mg/L), but growth and reproduction were more sensitive endpoints (42-d EC50 for both endpoints = 2.3 mg/L). Fathead minnows were less sensitive than amphipods, exhibiting no significant effects in all endpoints with the exception of uninflated swim bladder, which was significantly higher at 76 mg/L (15%) than controls (0%). Maximum concentrations of PFOA are generally in the ng/L range in global surface waters, but can reach the μg/L range in close proximity to major source inputs; therefore, environmental concentrations are well below those that caused toxicity in the current study. Our data will provide valuable information with which to assess the risk of PFOA at contaminated sites, and to set a target for site remediation.

The impact of risk management measures on the concentrations of per- and polyfluoroalkyl substances in source and treated drinking waters in Ontario, Canada

Risk management measures (RMMs) are a broad set of tools used in global treaties and national regulations to manage, ban or restrict the use of toxic chemicals. Per- and polyfluoroalkyl substances (PFAS) are a group of chemicals that are persistent, bioaccumulate, biomagnify and are inherently toxic to the environment and human health. For these reasons global RMMs have been imposed on the manufacture and use of select PFAS. To evaluate the occurrence and potential current risk of PFAS in the Ontario environment, PFAS were quantitatively measured in source waters pre- (2005-2007) and post- (2012-2016, 2018-2019) implementation of RMMs. Source water samples were collected pre- (n = 105), and post-RMMs (n = 326) from lake, river and groundwater and analyzed for up to 14 PFAS. Pre-RMMs, the most frequently detected PFAS in source water were perfluorooctanoic acid (PFOA; 83%) and perfluorooctane sulfonate (PFOS; 76%) followed by perfluorohexane sulfonate (PFHxS; 47%) and the maximum ∑PFAS₁₀ was 42.1 ng/L. Post-RMMs, the maximum ∑PFAS₁₀ (which includes PFOS) was statistically significantly reduced to 15.5 ng/L, well below the Federal Environmental Quality Guidelines for PFOS. To evaluate post-RMMs risk to human health, 226 drinking water samples were collected from 25 drinking water systems with conventional and advanced treatment. All individual (or ∑PFAS) concentrations are well below current and proposed Health advisory levels or regulatory guidelines/standards for PFAS in drinking water with calculated Risk Quotients (RQ) <0.02. This survey indicates that the implementation of RMMs for select PFAS have made a significant difference to the concentrations detected in source waters in Ontario, Canada.

Photochemical transformation of perfluoroalkyl acid precursors in water using engineered nanomaterials

The production of perfluoroalkyl acids (PFAAs) has been phased out over recent decades; however, no significant decline in their environmental concentrations has been observed. This is partly due to the photochemical decomposition of PFAAs precursors (PrePFAAs) which remain in extensive use. The decomposition of PrePFAAs may be accelerated by the light-activated engineered nanomaterials (ENMs) in water. In light of this hypothesis, we investigated the photochemical transformation of three PrePFAAs, which are 8:2 fluorotelomer sulfonic acid (8:2 FTSA), 8:2 fluorotelomer alcohol (8:2 FTOH), and 2-(N-ethylperfluorooctane-1-sulfonamido ethyl] phosphate (SAmPAP), in the presence of six ENMs under simulated sunlight irradiation. The transformation rates of 8:2 FTSA and 8:2 FTOH were increased by 2-6 times when in the presence of six ENMs. However, most of ENMs appeared to inhibit the decomposition of SAmPAP. The transformation rates of PrePFAAs were found to depend on the yield of reactive oxygen species generated by ENMs, but the rates were also related to compound photo-stability, adsorption to surfaces, and photo-shielding effects. The PrePFAAs are transformed to perfluorooctanoic acid (PFOA) or/and perfluorooctane sulfonate (PFOS) with higher toxicity and longer half-life, PFOA or PFOS and a few PFAAs having shorter carbon chain lengths. Higher concentrations of the PFAAs photodegradation products were observed in the presence of most of the ENMs.

Spatial and temporal variability of perfluoroalkyl substances in the Laurentian Great Lakes

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of fluorinated organic chemicals that have been used in industrial and consumer applications since the 1950s. PFAS are resistant to chemical and biological degradation and are ubiquitous in the environment, including in water, sediment, and biota in the Laurentian Great Lakes. This critical review evaluates the spatial and temporal variability of commonly studied perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl carboxylates (PFCAs) in the Great Lakes by synthesizing data collected in water, surface sediment, sediment cores, lake trout (Salvelinus namaycush), and herring gull (Larus argentatus) eggs. The lowest PFAS concentrations in all matrices are detected in Lake Superior, which is located in the most pristine region of the Great Lakes Basin. In contrast, higher concentrations are observed in Lakes Erie and Ontario, which are more impacted by industrial activity and wastewater discharge. The distribution of individual PFAS compounds also varies across the lakes in response to changes in PFAS sources, with higher proportions of PFSAs in the eastern lakes. Sediment and biota are enriched in long chain PFSAs and PFCAs relative to concentrations in the water column, as expected based on predicted partitioning behavior. Sediment cores and bioarchives consistently demonstrate that PFAS concentrations increased in the Great Lakes from the initial time points until the early 2000s. The available data indicate that PFOS and PFOA concentrations decline after this period in the upper Great Lakes, but are stable in Lake Ontario. However, these trends depend on the lake, the individual compound, and the organism considered.