Poly- and Perfluoroalkyl Substances (PFAS): Do They Matter to Aquatic Ecosystems?

Perfluoroalkyl substances: a risk for the aquatifc environment? A 1-year case study in river waters of central Italy

Perfluoroalkyl substances (PFASs) are a large class of persistent emerging pollutants, ubiquitous in different environmental compartments. In this study, twenty-one PFASs were determined in seventy-eight water samples collected from six different rivers in the Umbria region (central Italy) during a 13-month monitoring campaign. The sum of the twenty-one target analytes (Σ21PFASs) ranged from 2.0 to 68.5 ng L-1, with a mean value of 22.0 ng L-1. The highest concentrations of Σ21PFASs were recorded in the warmest months (from June to September) due to reduced river streamflow caused by low rainfall and high temperatures. PFASs with a number of carbon atoms between four and nine prevail over C10-C18 congeners due to their higher water solubility and to their increased use in industry. PFBA, followed by PFPeA, PFHxA, and PFOA, was the most abundant congeners detected in the analyzed river water samples. Finally, the calculation of risk quotients (∑RQs) has allowed to assess the risk for three aquatic organisms (fish, algae, and daphnid) deriving from the exposure to PFASs. The survey showed that the risk for the three aquatic organisms during the four seasons and throughout the year was always negligible. The only exception was a low risk for fish and daphnid in GEN river considering the annual exposure.

Harnessing the power of microbial consortia for the biodegradation of per- and polyfluoroalkyl substances: Challenges and opportunities

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants that pose significant risks to human health and ecosystems owing to their widespread use and resistance to degradation. This study examines the potential of microbial consortia as a sustainable and effective strategy for biodegrading PFAS. It highlights how these complex communities interact with various PFAS, including perfluorocarboxylic acids, perfluorosulfonic acids, fluorotelomer alcohols, and fluorotelomer-based precursors. Despite the potential of microbial consortia, several challenges impede their application in PFAS remediation, including effective microbial species identification, inherent toxicity of PFAS compounds, co-contaminants, complications from biofilm formation, diversity of environmental matrices, and competition with native microbial populations. Future research should focus on refining characterization techniques to enhance our understanding of microbial interactions and functions within consortia. Integrating bioinformatics and system biology will enable a comprehensive understanding of microbial dynamics and facilitate the design of tailored consortia for specific PFAS compounds. Furthermore, field applications and pilot studies are essential for assessing the real-world effectiveness of microbial remediation strategies. Ultimately, advancing our understanding and methodologies will lead to efficient biodegradation processes and positioning microbial consortia as viable solutions for PFAS-contaminated environments.

Bioaccumulation and Transfer of Legacy and Emerging Per- and Polyfluoroalkyl Substances throughout the Lifecycle of a Tropical Amphibian Species Fejervarya limnocharis

Pollutant bioaccumulation in amphibians is complex owing to their unique physiological characteristics and biphasic lifecycle. This study investigated per- and polyfluoroalkyl substances (PFASs) in water, insects, and rice frogs (Fejervarya multistriata) throughout their entire lifecycle. The median total PFAS concentrations were 1.15-5.53, 65.6, 7.31, 7.33, and 2.24-31.6 ng/g dry weight in insect, egg, tadpole, juvenile frog, and adult frog samples, respectively. Concentrations of PFASs with protein-water distribution coefficients (log KPW) > 2 decreased from eggs to tadpoles and were constant from tadpoles to frogs. By contrast, concentrations of PFASs with log KPW < 2 reached apex concentrations in tadpoles and juvenile frogs. No growth dilution was observed for PFASs from juvenile to adult frogs. Stable isotope and fatty acid compositions in frog and insect samples indicated little change in diet sources during frog growth. The bioaccumulation factors of PFASs with log KPW < 3 were decreased in tadpoles and frogs, suggesting preferential accumulation of low-proteinphilic PFASs from water. The distinct bioaccumulation profiles of PFASs during rice frog development emphasize the need for ecological and toxicological studies conducted throughout the amphibian lifecycle.

Screening of estrogen receptor activity of per- and polyfluoroalkyl substances based on deep learning and in vivo assessment

Over the past decades, exposure to per- and polyfluoroalkyl substances (PFAS), a group of synthetic chemicals notorious for their environmental persistence, has been shown to pose increased health risks. Despite that some PFAS were reported to have endocrine-disrupting toxicity in previous studies, accurate prediction models based on deep learning and the underlying structural characteristics related to the effect of molecular fluorination remain limited. To address these issues, we proposed a stacking deep learning architecture, GXDNet, that integrates molecular descriptors and molecular graphs to predict the estrogen receptor α (ERα) activities of compounds, enhancing the generalization ability compared to previous models. Subsequently, we screened the ERα activity of 10,067 PFAS molecules using the GXDNet model and identified potential ERα binders. The representative PFAS molecules with the top docking scores showed that the introduction of fluorinated alkane chains significantly increased the binding affinities of parent molecules with ERα, suggesting that the combination of phenol structural fragments and fluorinated alkane chains has a synergistic effect in improving the binding capacity of the ligands to ERα. The binding modes, SHapley Additive Explanations analysis, and attention map emphasized the importance of π-π stacking and hydrogen bonding interactions with the phenol group, while the fluorinated alkane chain enhanced the interaction with the hydrophobic amino acids of the active pocket. Experimental validation using zebrafish models further confirmed the ERα activity of the representative PFAS molecules. Overall, the current computational workflow is beneficial for the toxicological screening of emerging PFAS and accelerating the development of eco-friendly PFAS molecules, thereby mitigating the environmental and health risks associated with PFAS exposure.

Observational studies on per- and polyfluoroalkyl substance toxicity in marine species: hints for the extrapolation of a screening value

A statistical procedure has been developed to derive a screening value from an observational study related to the developmental toxicity observed in loggerhead turtle (Caretta caretta) eggs exposed to long chain per- and polyfluoroalkyl substances (PFAS). A dataset of 41 nests in which the hatching rate was inversely correlated with the increase in the PFAS concentration in unhatched eggs was processed via a categorical regression approach. After outliers identification and removal, categorical regression analysis tested the relationships of the outcomes with the following parameters: perfluoro-nonanoic (PFNA), decanoic (PFDA), undecanoic (PFUdA), and dodecanoic (PFDoA) acids; perfluoroctansulfonate (PFOS); polychlorobiphenyls (PCBs) 28, 52, 101, 138, 153, 180; lead (Pb), total mercury (Hgtot), and cadmium (Cd); and other factors, such as "nest site," "clutch size," "incubation duration," and "nest minimum depth," as confounders/modifiers of the hatching rate. Among considered contaminants, PFOS, PFDA, and PFNA only were significant (p ˂ 0.05), as were "nest site," "clutch size," and "incubation duration," confirming their possible role in decreasing the hatching rate of sea turtle eggs. According to a chemical-specific visual strategy, PFOS only showed a typical monotonic dose/response curve, which allowed the identification of provisional hypothetical thresholds of PFOS, 1,386 (CI95 = 1,080-1,692) ng/kg, corresponding to average hatching rates of 93.3% (CI95 = 91.4%-95.2%). Our preliminary results indicate the feasibility of the extrapolation of a screening value from observational studies under the following requirements: (a) individuation of most influencing factors for the outcome; (b) datasets referred to baseline contamination; (c) selection of undisturbed nests; (d) appropriate statistical multivariate methodology. This work aims to contribute to the New Approach Methods (NAMs) to assess PFAS early-stage embriotoxicity in marine biota.

Interactions of a PFOS/sodium nitrite mixture in Chinese mitten crab (Eriocheir sinensis): Impacts on survival, growth, behavior, energy metabolism and hepatopancreas transcriptome

Perfluorooctanesulfonic acid (PFOS) and sodium nitrite may have complex adverse effects on aquatic animals. This study assessed the interactive effects of PFOS and sodium nitrite on Chinese mitten crab (Eriocheir sinensis). A 2 × 3 factorial experiment with 0, 0.1, and 5 mg/L PFOS and 0, 3.50 mg/L sodium nitrite evaluated impacts on growth, behavior, oxygen consumption, health, energy metabolism, and hepatopancreas transcriptome. PFOS <0.1 mg/L with 3.50 mg/L nitrite significantly decreased PFOS accumulation in the hepatopancreas and improved feeding rates and hepatopancreas structure (P < 0.05). Under 5 mg/L PFOS and nitrite, survival, weight gain, hepatosomatic index, and feeding rate significantly decreased (P < 0.05). PFOS (0.1 mg/L) with nitrite significantly prolonged righting response time and increased locomotion speed (P < 0.05). PFOS (5 mg/L) significantly decreased serum triglyceride and lactate levels, while PFOS and nitrite decreased glucose, triglyceride, and glycogen levels and increased lactate in hepatopancreas (P < 0.05). Transcriptomic analysis indicated that PFOS affects p53 signaling, cell cycle and neurotransmission pathways, with notable changes in cell proliferation genes (pcna, ccna, cdk1, cdk2, rbx1) primarily downregulated by PFOS. Overall, PFOS disrupts neurotransmitter regulation and causes hepatopancreatic damage, while nitrite can reduce the toxicity of PFOS by decreasing its hepatopancreas accumulation. However, high levels of PFOS combined with sodium nitrite exacerbate toxicity, emphasizing the need for comprehensive assessment of environmental pollutant interactions.

Non-Invasive Matrices for the Human Biomonitoring of PFAS: An Updated Review of the Scientific Literature

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in consumer and industrial products due to their unique physicochemical properties. However, their persistence and bioaccumulative potential pose significant environmental and human health risks. This review focuses on the use of non-invasive matrices-urine, hair, and nails-for the human biomonitoring of PFAS, highlighting key findings from scientific studies. While urine offers a non-invasive and practical option, its limited sensitivity for long-chain PFAS requires further analytical advances. Hair and nails have demonstrated potential for use in biomonitoring, with higher detection frequencies and concentrations for certain PFAS compared to urine. The variability in PFAS levels across studies reflects differences in population characteristics, exposure sources, and geographic regions. This review emphasizes the need for standardized analytical methods, expanded population studies, and the use of complementary matrices to enhance the accuracy and reliability of PFAS exposure assessment.

Forever chemicals don't make hero mutant ninja turtles: Elevated PFAS levels linked to unusual scute development in newly emerged freshwater turtle hatchlings (Emydura macquarii macquarii) and a reduction in turtle populations

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants known to pose significant risks to human and wildlife health. Freshwater turtles (Emydura macquarii macquarii), as long-lived species inhabiting aquatic ecosystems, are particularly vulnerable to PFAS bioaccumulation. This study investigated the multifaceted impact of PFAS contamination on these turtles, focusing on metabolic disruptions, reproductive success, hatchling health, and population impacts. Comprehensive analyses, including proteomics, lipidomics, metabolomics, and histopathology, were conducted on turtles from PFAS-impacted, control, and reference sites. The findings reveal significant metabolic disruptions in PFAS-exposed turtles, with alterations in amino acid and lipid metabolism, energy production, and oxidative stress responses. Proteomic analysis identified several health biomarkers indicative of early disease progression. Despite high levels of PFAS in tissues and organs, no gross or histopathological phenotypical abnormalities were directly linked to PFAS exposure. Gravid females from contaminated sites exhibited altered egg composition, particularly in magnesium to calcium ratios, potentially affecting eggshell strength. Biochemical profiles of egg albumin and yolk indicated significant differences in metabolites and lipids between contaminated and reference sites, suggesting potential impacts on embryo development. Hatchling deformities were notably higher and with increased frequency in terms of the types of deformities at the PFAS-impacted sites, with common defects including abnormal intergular scale shapes and marginal scale counts. Furthermore, the demographic profile of the turtle population showed a lack of juvenile turtles at contaminated sites, indicating reduced recruitment and potential long-term population declines. This indicates a field-based demonstration of an Adverse Outcome Pathway, from elevated levels of PFAS in the turtles, to biochemical perturbations within the animals, and finally population effects. These findings underscore the urgent need for regulatory measures to address PFAS contamination and its detrimental effects on wildlife.

Tissue distribution and temporal and spatial assessment of per- and polyfluoroalkyl substances (PFAS) in smallmouth bass (Micropterus dolomieu) in the mid-Atlantic United States

Per- and polyfluoroalkyl substances (PFAS) have become an environmental issue worldwide. A first step to assessing potential adverse effects on fish populations is to determine if concentrations of concern are present in a region and if so, in which watersheds. Hence, plasma from adult smallmouth bass Micropterus dolomieu collected at 10 sites within 4 river systems in the mid-Atlantic region of the United States, from 2014 to 2019, was analyzed for 13 PFAS. These analyses were directed at better understanding the presence and associations with land use attributes in an important sportfish. Four substances, PFOS, PFDA, PFUnA, and PFDoA, were detected in every plasma sample, with PFOS having the highest concentrations. Sites with mean plasma concentrations of PFOS below 100 ng/ml had the lowest percentage of developed landcover in the upstream catchments. Sites with moderate plasma concentrations (mean PFOS concentrations between 220 and 240 ng/ml) had low (< 7.0) percentages of developed land use but high (> 30) percentages of agricultural land use. Sites with mean plasma concentrations of PFOS > 350 ng/ml had the highest percentage of developed land use and the highest number PFAS facilities that included military installations and airports. Four of the sites were part of a long-term monitoring project, and PFAS concentrations of samples collected in spring 2017, 2018, and 2019 were compared. Significant annual differences in plasma concentrations were noted that may relate to sources and climatic factors. Samples were also collected at two sites for tissue (plasma, whole blood, liver, gonad, muscle) distribution analyses with an expanded analyte list of 28 PFAS. Relative tissue distributions were not consistent even within one species of similar ages. Although the long-chained legacy PFAS were generally detected more frequently and at higher concentrations, emerging compounds such as 6:2 FTS and GEN X were detected in a variety of tissues.

Occurrence and profiles of perfluoroalkyl substances in wastewaters of chemical industrial parks and receiving river waters: Implications for the environmental impact of wastewater discharge

A total of 17 groups of wastewaters from the chemical industrial parks and matched receiving river waters were collected in the east of China. The measured total concentrations of 21 analyzed PFAS analogues (∑21PFAS) in the influents and effluents of the wastewater treatment plants (WWTPs) were in the range of 0.172-20.6 μg/L (mean: 18.2 μg/L, median: 3.9 μg/L) and 0.167-93.6 μg/L (mean: 10.8 μg/L, median: 1.12 μg/L), respectively, which were significantly higher than those observed in the upstream (range: 0.0158-7.05 μg/L, mean: 1.09 μg/L, median: 0.482 μg/L) and downstream (range: 0.0237-1.82 μg/L, mean: 0.697 μg/L, median: 0.774 μg/L) receiving waters. Despite the concentrations and composition profiles of PFAS varied in the water samples from different sampling sites, PFOA was generally the major PFAS analogue in the research areas, mainly due to the history of PFOA production and usage as well as the specific exemptions. The calculated concentration ratios of the short-chain PFCAs and PFSAs to their respective predecessors (PFOA and PFOS) in most of the samples far exceeded 1, indicating a shift from legacy PFOA and PFOS to short-chain PFAS in the research areas. Correlation network analysis and the calculated concentration ratios of PFAS in the effluents versus influents indicated transformation may have occurred during the water treatment processes and PFAS could not be efficiently removed in the WWTPs. Wastewater discharge of chemical industrial parks is a vital source of PFAS dispersed into the aquatic environment.

Advancements in Surfactant Carriers for Enhanced Oil Recovery: Mechanisms, Challenges, and Opportunities

Enhanced oil recovery (EOR) techniques are crucial for maximizing the extraction of residual oil from mature reservoirs. This review explores the latest advancements in surfactant carriers for EOR, focusing on their mechanisms, challenges, and opportunities. We delve into the role of inorganic nanoparticles, carbon materials, polymers and polymeric surfactants, and supramolecular systems, highlighting their interactions with reservoir rocks and their potential to improve oil recovery rates. The discussion includes the formulation and behavior of nanofluids, the impact of surfactant adsorption on different rock types, and innovative approaches using environmentally friendly materials. Notably, the use of metal oxide nanoparticles, carbon nanotubes, graphene derivatives, and polymeric surfacants and the development of supramolecular complexes for managing surfacant delivery are examined. We address the need for further research to optimize these technologies and overcome current limitations, emphasizing the importance of sustainable and economically viable EOR methods. This review aims to provide a comprehensive understanding of the emerging trends and future directions in surfactant carriers for EOR.

Release of perfluoroalkyl acids from sediments under the effects of the discharge ratio and flow flux at a Y-shaped confluence

The sediments in riverine environments contain notably high concentrations of perfluoroalkyl acids (PFAAs), which may be released into the water body under different hydrodynamic forces, such as those occurring at Y-shaped confluences. The release of PFAAs may pose a significant risk to the surrounding aquatic ecosystems. However, our understanding of the release and transport of PFAAs from sediments at Y-shaped confluences remains unclear. Thus, in this study, we performed a series of flume experiments to explore the effects of discharge ratio and total flow flux on the release and redistribution of PFAAs. The results indicated that these two parameters significantly affected the hydrodynamic features of confluences and the water physicochemical parameters. PFAA concentrations in the dissolved phase and suspended particulate matter (SPM) rose significantly as the discharge ratio and total flow flux increased. The dissolved phase was the predominant loading form of PFAAs, with short-chain PFAAs being the main kind, while long-chain PFAAs were dominant in the SPM. The spatial distribution pattern of PFAAs in sediments at the confluence exhibited a high degree of correspondence with hydrodynamic zones. The separation zone and maximum velocity zone were consistent with sediment regions with low and high capacities to release PFAAs, respectively. The patterns of variation in PFAA distribution were comparable to those observed in hydrodynamic zones as the discharge ratio and total flow flux varied. Furthermore, these two parameters altered the partitioning behaviors of PFAAs; specifically, the PFAAs in sediments tended to be released into the pore-water, while the liberated PFAAs tended to attach to SPM. Linear regression and correlation analyses suggested that the stream-wise and vertical flow velocity components near the sediment-water interface were the primary contributors to sediment suspension and PFAA exchange between the water column and pore-water. These findings will help us to understand the patterns of PFAA release in sediments at Y-shaped confluences and assist in the management of PFAA-contaminated sediments at these locations.

The association between endocrine disrupting chemicals and nonalcoholic fatty liver disease: A systematic review and meta-analysis

Nonalcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver disease worldwide. Epidemiological studies have reported that exposure of the population to environmental endocrine-disrupting chemicals (EDCs) is associated with NAFLD. However, EDCs are of different types, and there are inconsistencies in the relevant evidence and descriptions, which have not been systematically summarized so far. Therefore, this study aimed to determine the association between population exposure to EDCs and NAFLD. Three databases, including PubMed, Web of science, and Embase were searched, and 27 articles were included in this study. Methodological quality, heterogeneity, and publication bias of the included studies were assessed using the Newcastle-Ottawa scale, I2 statistics, Begg's test, and Egger's test. The estimated effect sizes of the included studies were pooled and evaluated using the random-effects model (I2 > 50 %) and the fixed-effects model ( I2 < 50 %). The pooled-estimate effect sizes showed that population exposure to Phthalates (PAEs) (OR = 1.18, 95 % CI:1.03-1.34), cadmium (Cd) (OR = 1.37, 95 % CI:1.09-1.72), and bisphenol A (OR = 1.43, 95 % CI:1.24-1.65) were positively correlated with the risk of NAFLD. Exposure to mercury (OR =1.46, 95 % CI:1.17-1.84) and Cd increased the risk of "elevated alanine aminotransferase". On the contrary, no significant association was identified between perfluoroalkyl substances (OR =0.99, 95 % CI:0.93-1.06) and NAFLD. However, female exposure to perfluorooctanoic acid (OR =1.82, 95 % CI:1.01-3.26) led to a higher risk of NAFLD than male exposure. In conclusion, this study revealed that EDCs were risk factors for NAFLD. Nonetheless, the sensitivity analysis results of some of the meta-analyses were not stable and demonstrated high heterogeneity. The evidence for these associations is limited, and more large-scale population-based studies are required to confirm these findings.

Separation of Perfluorooctanoic Acid from Water Using Meso- and Macroporous Syndiotactic Polystyrene Gels

Per- and polyfluoroalkyl substances are an emerging class of contaminants that are environmentally persistent, bioaccumulative, and noxious to human health. Among these, perfluorooctanoic acid (PFOA) molecules are widely found in ground and surface water sources. A novel high surface area, meso- and macroporous syndiotactic polystyrene (sPS) wet gel is used in this work as the adsorbent of PFOA molecules from water at environmentally relevant PFOA concentrations (≤1 μg/L) and cleanse water to below the U.S. EPA's 2023 health advisory limit of 4 parts per trillion (ppt). The sigmoidal shape of the PFOA adsorption isotherm indicates a two-step adsorption mechanism attributed to the strong affinity of PFOA molecules for the sPS surface and molecular aggregation at solid-liquid interfaces or within the pores of the sPS wet gel. The adsorption kinetics and the effects of sPS wet gel porosity, pore size, and pore volume on the removal efficiency are reported. The adsorption kinetics is seen to be strongly dependent on pore size and pore volume.

Occurrence and pattern of legacy and emerging per- and Poly-FluoroAlkyl substances (PFAS) in eggs of loggerhead turtle Caretta caretta from western Mediterranean

Per-and Poly-FluoroAlkyl Substances (PFAS) are a class of persistent, toxic, and mobile and chemicals both from industrial sources and from the use and disposal of Consumers products containing PFAS, whose concentration in marine food webs could pose a toxicological risk for biota and humans. In 2021, unhatched eggs were sampled from 41 loggerhead turtle Caretta caretta nests from the Italian shores of the Campania Region (Southern Italy). Whole eggs were analysed for the presence of 66 legacy and emerging PFAS with Liquid Chromatography coupled to Hybrid High Resolution Mass Spectrometry. A median Σ66 Per- and Poly-FluoroAlkyl Substances value of 3.34 ng/g egg fresh weight was found; perfluoroctane sulfonate (PFOS) represented the most contributing congener (47%), followed by perfluoro-n-undecanoic acid, perfluoro-n-tridecanoic acid, perfluoro-n-decanoic acid, perfluoro-n-decanoic acid, and perfluoro-n-tetradecanoic acid, respectively. Such compounds showed a log-norm distribution, suggesting found concentrations could represent the baseline levels in the considered sampling area. Emerging ChloroPolyFluoroPolyEthers Carboxylic Acids (ClPFECAs) were found in 20 out of 41 samples in the range 0.01-1.59 ng/g. Four samples had 20-100 fold higher concentration compared to that of other samples, suggesting the presence of hot spot areas possibly related to presence of fluoropolymer-based marine litter turtles may ingest. The analysis of two paired eggs/liver samples recovered from stranded animals revealed PFAS concentration in the same order of magnitude, supporting the role of vitellogenin in their selective transfer to yolk. Significant (P = 0.0155) Kendall negative correlation coefficient of -0.2705 among PFOS content in eggs and the recorded hatching success prompts for further investigation on associated exposure assessment and related eco-toxicity risk. This work reports for the first time PFAS presence in georeferenced loggerhead turtle eggs of the Mediterranean Sea and results represent a starting point to study PFAS time-trends in this vulnerable species.