Characterization of occurrence, sources and sinks of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in a tropical urban catchment

Southeast Asia's environmental challenges: emergence of new contaminants and advancements in testing methods

Emerging contaminants, including pharmaceuticals, personal care products, microplastics, and per- and poly-fluoroalkyl substances, pose a major threat to both ecosystems and human health in Southeast Asia. As this region undergoes rapid industrialization and urbanization, the increasing presence of unconventional pollutants in water bodies, soil, and various organisms has become an alarming concern. This review comprehensively examines the environmental challenges posed by emerging contaminants in Southeast Asia and recent progress in toxicity testing methods. We discuss the diverse range of emerging contaminants found in Southeast Asia, shedding light on their causes and effects on ecosystems, and emphasize the need for robust toxicological testing methods. This review is a valuable resource for researchers, policymakers, and environmental practitioners working to mitigate the impacts of emerging contaminants and secure a sustainable future for Southeast Asia.

Silver dendrite metasurface SERS substrates prepared by photoreduction method for perfluorooctanoic acid detection

Perfluorooctanoic acid (PFOA), a novel organic pollutant, has been shown to be toxic, persistent, bioaccumulative, long-range transportable, and globally prevalent. This article is based on surface enhanced Raman scattering (SERS) spectroscopy analysis technology. The monolayer of SiO2 was prepared by chemical reduction etching self-assembly method and silver dendrites were grown on it, thus forming the SERS substrate with silver dendrite Metasurface structure with Raman detection enhancement factor up to 2.32 × 105. The prepared silver dendrite Metasurface SERS substrate was applied to the qualitative and quantitative detection of PFOA, with a quantitative detection limit of 15.89 ppb. The results of this paper provide a new, simple, and quick method for the detection of PFOA in the environment.

Exposure to perfluoroalkyl substances and women's fertility outcomes in a Singaporean population-based preconception cohort

OBJECTIVES

Experimental models have demonstrated a link between exposure to perfluoroalkyl substances (PFAS) and decreased fertility and fecundability; however, human studies are scarce. We assessed the associations between preconception plasma PFAS concentrations and fertility outcomes in women.

METHODS

In a case-control study nested within the population-based Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO), we measured PFAS in plasma collected in 2015-2017 from 382 women of reproductive age trying to conceive. Using Cox proportional hazards regression (fecundability ratios [FRs]) and logistic regression (odds ratios [ORs]) models, we assessed the associations of individual PFAS with time-to-pregnancy (TTP), and the likelihoods of clinical pregnancy and live birth, respectively, over one year of follow-up, adjusting for analytical batch, age, education, ethnicity, and parity. We used Bayesian weighted quantile sum (BWQS) regression to assess the associations of the PFAS mixture with fertility outcomes.

RESULTS

We found a 5-10 % reduction in fecundability per quartile increase of exposure to individual PFAS (FRs [95 % CIs] for clinical pregnancy = 0.90 [0.82, 0.98] for PFDA; 0.88 [0.79, 0.99] for PFOS; 0.95 [0.86, 1.06] for PFOA; 0.92 [0.84, 1.00] for PFHpA). We observed similar decreased odds of clinical pregnancy (ORs [95 % CIs] = 0.74 [0.56, 0.98] for PFDA; 0.76 [0.53, 1.09] for PFOS; 0.83 [0.59, 1.17] for PFOA; 0.92 [0.70, 1.22] for PFHpA) and live birth per quartile increases of individual PFAS and the PFAS mixture (ORs [95 % CIs] = 0.61 [0.37, 1.02] for clinical pregnancy, and 0.66 [0.40, 1.07] for live birth). Within the PFAS mixture, PFDA followed by PFOS, PFOA, and PFHpA were the biggest contributors to these associations. We found no evidence of association for PFHxS, PFNA, and PFHpS and the fertility outcomes examined.

CONCLUSIONS

Higher PFAS exposures may be associated with decreased fertility in women. The potential impact of ubiquitous PFAS exposures on infertility mechanisms requires further investigation.

Combining target analysis with sum parameters-a comprehensive approach to determine sediment contamination with PFAS and further fluorinated substances

Recent studies aiming at a fluorine mass balance analysis in sediments combined the determination of extractable organic fluorine (EOF) with target analysis. They reported high fractions of unidentified organic fluorine (UOF) compounds, as the target analysis covers only a limited number of per- and polyfluoroalkyl substances (PFAS). For this reason, in this study, a comprehensive approach was used combining target analysis with an extended PFAS spectrum, the EOF and a modified total oxidisable precursor (TOP) assay, which includes trifluoroacetic acid, to determine the PFAS contamination in sediments (n=41) and suspended solids (n=1) from water bodies in Northern Germany (Lower Saxony). PFAS are ubiquitous in the sediments (detected in 83% of the samples). Perfluorinated carboxylic acids (PFCAs) were found in 64% of the samples; perfluorinated sulfonic acids (PFSAs) were detected less frequently (21%), with the highest concentration observed for perfluorooctanesulfonic acid (PFOS). Levels of precursors and substitutes were lower. Applying the TOP assay resulted in an increase in PFCAs in 43% of the samples analysed. In most cases, target analysis and the TOP assay could not account for the EOF concentrations measured. However, as the fraction of UOF decreased significantly, the application of the TOP assay in fluorine mass balance analysis proved to be an important tool in characterising the PFAS contamination of riverine sediments.

Source, fate, transport and modelling of selected emerging contaminants in the aquatic environment: Current status and future perspectives

The occurrence of emerging contaminants (ECs), such as pharmaceuticals and personal care products (PPCPs), perfluoroalkyl and polyfluoroalkyl substances (PFASs) and endocrine-disrupting chemicals (EDCs) in aquatic environments represent a major threat to water resources due to their potential risks to the ecosystem and humans even at trace levels. Mathematical modelling can be a useful tool as a comprehensive approach to study their fate and transport in natural waters. However, modelling studies of the occurrence, fate and transport of ECs in aquatic environments have generally received far less attention than the more widespread field and laboratory studies. In this study, we reviewed the current status of modelling ECs based on selected representative ECs, including their sources, fate and various mechanisms as well as their interactions with the surrounding environments in aquatic ecosystems, and explore future development and perspectives in this area. Most importantly, the principles, mathematical derivations, ongoing development and applications of various ECs models in different geographical regions are critically reviewed and discussed. The recommendations for improving data quality, monitoring planning, model development and applications were also suggested. The outcomes of this review can lay down a future framework in developing a comprehensive ECs modelling approach to help researchers and policymakers effectively manage water resources impacted by rising levels of ECs.

Next generation per- and poly-fluoroalkyl substances: Status and trends, aquatic toxicity, and risk assessment

Widespread application of poly- and per-fluoroalkyl substances (PFAS) has resulted in some substances being ubiquitous in environmental matrices. That and their resistance to degradation have allowed them to accumulate in wildlife and humans with potential for toxic effects. While specific substances of concern have been phased-out or banned, other PFAS that are emerging as alternative substances are still produced and are being released into the environment. This review focuses on describing three emerging, replacement PFAS: perfluoroethylcyclohexane sulphonate (PFECHS), 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFAES), and hexafluoropropylene oxide dimer acid (HFPO-DA). By summarizing their physicochemical properties, environmental fate and transport, and toxic potencies in comparison to other PFAS compounds, this review offers insight into the viabilities of these chemicals as replacement substances. Using the chemical scoring and ranking assessment model, the relative hazards, uncertainties, and data gaps for each chemical were quantified and related to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) based on their chemical and uncertainty scores. The substances were ranked PFOS > 6:2 Cl-PFAES > PFOA > HFPO-DA > PFECHS according to their potential toxicity and PFECHS > HFPO-DA > 6:2 Cl-PFAES > PFOS > PFOA according to their need for future research. Since future uses of PFAS remain uncertain in the face of governmental regulations and production bans, replacement PFAS will continue to emerge on the world market and in the environment, raising concerns about their general lack of information on mechanisms and toxic potencies.

Occurrence, distribution, and risk assessment of perfluoroalkyl acids in drinking water sources from the lower Yangtze River

The occurrence, spatial distribution, potential sources, and risk assessment of 14 perfluoroalkyl acids (PFAAs), including 11 perfluoroalkyl carboxylic acids and 3 perfluoroalkyl sulfonates acids, were investigated in 21 drinking water sources from the lower Yangtze River in November 2019. The total PFAAs (∑PFAAs) concentrations ranged from 39.3 to 220.3 ng/L, and perfluorooctanoic acid and perfluorooctanesulfonate were predominant with average concentrations of 19.4 and 15.4 ng/L, respectively. The higher ∑PFAAs concentrations in the southern shore and downstream could be attributed to industrial development and surface runoff/tide currents, respectively. Principal component analysis-multiple linear regression revealed that the primary sources of PFAAs were fluororesin coatings/metal plating, surface runoff/textile, effluent discharge/food packaging, and leather/fabrics. Human intake risks of PFAAs were assessed by target hazard quotient (THQ), which showed that human health risks of PFAAs decreased with increasing age, excluding 13-17 years age group. Moreover, the total exposure risks of PFOA/PFOS in all sampling sites to people aged over 18 years calculated based on contribution from drinking water were noted to be at safe level. The results obtained were helpful for improving our understanding of human health risks of PFAAs, and expanding our knowledge on PFAAs in drinking water.

Probiotic supplementation mitigates the developmental toxicity of perfluorobutanesulfonate in zebrafish larvae

Perfluorobutanesulfonate (PFBS) is an emerging pollutant of international concern, which is found to impair the early embryonic development of fishes. In the context of ubiquitous and persistent pollution, it is necessary to explore mitigatory strategies against the developmental toxicity of PFBS. In this study, zebrafish larvae were acutely exposed to 0, 1, 3.3 and 10 mg/L of PFBS till 168 h post-fertilization (hpf), during which probiotic Lactobacillus rhamnosus bacteria were administered via the exposure media. After the singular or combined exposure, interaction between PFBS and probiotics on the growth of zebrafish larvae was measured. PFBS exposure significantly decreased the larval body weight, weight gain and specific growth rate, while probiotic supplementation efficiently inhibited the growth retardation caused by PFBS. Furthermore, PFBS and probiotic combinations remarkably activated the antioxidant capacity to timely scavenge the reactive oxidative species and protect the larvae from lipid peroxidation. Biochemical assay and fluorescent staining verified that PFBS exposure significantly promoted the production of bile acids, which were further enhanced by the probiotics. In coexposed zebrafish larvae, up-regulation of peroxisome proliferator-activated receptor (PPARb) would enhance the β-oxidation of fatty acids to meet the energy demand from larval growth, subsequently decreasing fatty acid concentrations. In addition, probiotic supplements masked the dysbiosis of PFBS and potently shaped the gut microbiota, which closely modulated the production of bile acids. Overall, the present findings underline the beneficial effects of probiotics to protect the developing larvae from the aquatic toxicities of PFBS, thus highlighting the potential application values of probiotic recipe in aquaculture and ecological reservation.

Distribution, partitioning behavior and potential source of legacy and alternative per- and polyfluoroalkyl substances (PFASs) in water and sediments from a subtropical Gulf, South China Sea

Legacy per- and polyfluoroalkyl acids (PFASs) have received global concern over the scientific and public community since this century. However, the information on alternative PFASs pollution in the marine environment, especially in the subtropical marine environment is extremely limited. This study investigated the occurrence, partitioning, potential sources, and ecological risks of PFASs, including perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), and alternative PFASs, in surface water and sediments from the subtropical Beibu Gulf, South China. Concentrations of total PFASs (∑PFASs) were in the range of 0.98-2.64 ng/L in water and 0.19-0.66 ng/g (dry weight, dw) in sediment, respectively. Perfluorooctanoic acid (PFOA) was the most abundant PFAS in water, while PFASs in sediment were dominated by perfluorooctanesulfonic acid (PFOS) and PFOA. Among investigated environmental parameters (total organic carbon (TOC), grain size, water pH, sediment pH, and salinity), TOC and salinity were the dominant factors influencing the sediment-water distribution coefficient (K_d) of PFOA, perfluorodecanoic acid (PFDA), and perfluorononanoic acid (PFNA). Log K_d and log soil organic carbon-water distribution coefficient (K_oc) both increase with increasing carbon chain length of PFASs. Significantly positive correlations between PFOS and perfluorohexanoic acid (PFHxA) (p < 0.05), PFOA and perfluoro-1-butane-sulfonamide (FBSA) were observed, suggesting that these PFASs might have similar sources and transport routes. Preliminary environmental risk assessment showed that PFOA and PFOS would not pose risks to the marine aquatic environment. This is the first comprehensive survey of legacy and alternative PFASs in a subtropical area of the Beibu Gulf, which provides significant data and scientific basis to better understand the fate of PFASs and pollution control management.

Occurrence and Ecological Risk Assessment of Perfluoroalkyl Substances (PFASs) in Water and Sediment from an Urban River in South China

The chemical substances in urban rivers influence municipal water systems and reflect the recent use of these chemicals by humans or industries around the urban center. In this study, seven perfluoroalkyl substances (PFASs)-perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), 2-perfluorohexyl ethanol (6:2 FTOH), 2-perfluorooctyl ethanol (8:2 FTOH), and 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (F-53B)-could be detected and quantified in river water and sediment samples collected from one tributary of the Liuxi River, which is part of Pearl River near Guangzhou in Guangdong province, South China. The fluxes of target PFASs into Liuxi River and their related ecological risks were further estimated. The total concentrations of PFASs (ΣPFASs) ranged from 506 to 3.16 × 10³ ng/L in water samples and 9.13 to 850 ng/L in sediment samples. The two dominant PFAS compounds were 6:2 FTOH and PFHpA, which accounted for more than 90.0% of ΣPFASs in river water and sediment. Correlation analysis showed that there was significant positive correlation (p < 0.01) between two selected PFASs (e.g., between 6:2 FTOH and PFHpA). Correlation analysis of PFASs in river water and sediment indicated most PFASs in sediment were partitioned from river water. The ecological risk assessment indicated that the detected PFASs have a low risk (HQ < 0.1) in river water and sediment to Daphnia magna in the Liuxi River.

Occurrence of perfluorinated carboxylic acids in Mexico City's wastewater: A monitoring study in the sewerage and a mega wastewater treatment plant

An analytical method based on liquid chromatography coupled to mass spectrometry was validated to quantify five perfluorinated carboxylic acids (PFCA) namely, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), and perfluoroundecanoic acid (PFUnA), in wastewater produced in a megacity. Sampling was performed on a monthly basis, obtaining samples from the undergrounded sewerage system and the main open-air canal transporting wastewater out the city. Steady levels of the sum of the target PFCA (ƩPFCA) were determined on both sites through the study: 419.4 ± 24.3 ng L^-1 in undergrounded sewage and 591.1 ± 39 ng L^-1 in the open-air canal. Short-chain PFCA (PFBA, PFHxA, and PFHpA) were abundant, while concentrations of PFOA and PFUnA remained lower in both sampling sites. The open-air canal was transected in four sampling points, which were sampled throughout the monitoring campaign, finding that furtive discharges of municipal and industrial wastewater increased the levels of short-chain PFCA, while those of PFOA and PFUnA were depleted. Relevant concentrations of PFBA (176.9 ± 3.3 ng L^-1), PFHxA (133.4 ± 2.5 ng L^-1), PFHpA (116.6 ± 3.9 ng L^-1), PFOA (133.1 ± 3.5 ng L^-1), and PFUnA (23.5 ± 6.5 ng L^-1) were found 60 km downstream, where the wastewater transported by the open-air canal is used in irrigation. A fraction of sewage is treated in a conventional wastewater treatment plant. The concentration of short-chain PFCA increased in effluent, adding extra loads of PFBA, PFHxA, and PFHpA to the environment.

Isomers of emerging per- and polyfluoroalkyl substances in water and sediment from the Cape Fear River, North Carolina, USA

Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous environmental contaminants found in many parts of the globe and in all environmental compartments. The phase out of legacy C8 PFAS has led to an increase in functionality of the carbon backbone chain to include ether linkages and branching points. With the increased production of functionalized PFAS, there remains a paucity of information regarding the occurrence of constitutional isomers in the environment. In this study, a series of novel PFAS constitutional isomers were detected by high resolution mass spectrometry and characterized by MS/MS in river water collected weekly over 40 weeks. Constitutional isomers of C₄H₂F₈O₄S₁ (-1.8 ± 2.5 ppm) were detected for the first time in 83% of the samples analyzed and the MS/MS fragmentation patterns clearly indicated there were two coeluting isomers present. Two chromatographically resolved peaks with deprotonated molecular formula C₇H₁F₁₄O₅S₁ (1.9 ± 2.7 and 2.2 ± 3.1 ppm) were detected in 85% of the samples measured. MS/MS fragmentation patterns and a standard provided by a fluorochemical manufacturer confirmed the two isomers. A series of novel chlorinated PFAS were detected (M-1: C₁₁H₁Cl₁F₂₀O₅ 0.9 ± 2.7 ppm and C₁₄H₁Cl₁F₂₆O₆ 2.1 ± 2.6 ppm) in 34% of the water samples analyzed. The exact structure is not confirmed. River sediment collected below the water sample location contained several of the compounds detected in the water column illustrating the connectivity between the environmental compartments. Results highlight the need for further studies on the occurrence of isomers and authentic standards to confirm structures.

Suspended sediment exacerbates perfluorooctane sulfonate mediated toxicity through reactive oxygen species generation in freshwater clam Corbicula fluminea

Perfluorooctane sulfonate (PFOS) potentially adsorbs on the surface of suspended sediment (SPS), which can develop a toxic "pool" bioavailable to benthic organisms. In this study, the freshwater clam Corbicula fluminea was employed as a zoobenthos model to study the effects of SPS (collected from the Yellow River) on the bioaccumulation and toxicity (from the molecular level to cellular and physiological levels) caused by PFOS exposure. Besides, the enhanced integrated biomarker response (EIBR) system was applied as an index to evaluate the in-depth toxic effects of PFOS and SPS single and co-exposure at various treatment levels. Our results demonstrated that PFOS-SPS co-exposure (at sub-lethal doses of PFOS) significantly increased the bioaccumulation of PFOS, and induced the elevated levels of reactive oxygen species (ROS), the significantly increased activities of superoxide dismutase (SOD) and catalase (CAT) enzymes, the significantly increased content of malondialdehyde (MDA), and the significantly upregulated expression levels of sod, selenium-dependent glutathione peroxidase (se-gpx), heat shock protein 22 (hsp22), heat shock protein 40 (hsp40) and cytochrome P450 30 (cyp30) genes. Further, the co-exposure induced the significantly higher histopathological alterations in the gonads and digestive glands, and even elevated the inhibition of siphoning behavior in clams. In addition, the EIBR index also revealed the highest values for PFOS and SPS co-exposure, compared to the individual SPS or PFOS exposure. The results indicated that at high levels of PFOS exposure (especially at 1000 μg/L), the presence of SPS might increase the generation of ROS by influencing the bioaccumulation of PFOS, which enhanced the toxicity of PFOS to C. fluminea. These results potentially provide basic information for the comprehensive evaluation of the toxic effects of PFOS on benthos in a multi-sediment river ecosystem.

Environmental levels and human body burdens of per- and poly-fluoroalkyl substances in Africa: A critical review

Per- and polyfluoroalkyl substances (PFASs) are known organic pollutants with adverse health effects on humans and the ecosystem. This paper synthesises literature about the status of the pollutants and their precursors, identifies knowledge gaps and discusses future perspectives on the study of PFASs in Africa. Limited data on PFASs prevalence in Africa is available because there is limited capacity to monitor PFASs in African laboratories. The levels of PFASs in Africa are higher in samples from urban and industrialized areas compared to rural areas. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the dominant PFASs in human samples from Africa. Levels of PFOS and PFOA in these samples are lower than or comparable to those from industrialized countries. PFOA and PFOS levels in drinking water in Africa are, in some cases, higher than the EPA drinking water guidelines suggesting potential risk to humans. The levels of PFASs in birds' eggs from South Africa are higher, while those in other environmental media from Africa are lower or comparable to those from industrialized countries. Diet influences the pollutant levels in fish, while size and sex affect their accumulation in crocodiles. No bioaccumulation of PFASs in aquatic systems in Africa could be confirmed due to small sample sizes. Reported sources of PFASs in Africa include municipal landfills, inefficient wastewater treatment plants, consumer products containing PFASs, industrial wastewater and urban runoff. Relevant stakeholders need to take serious action to identify and deal with the salient sources of PFASs on the African continent.

Oxidative stress and mitochondrial membrane potential are involved in the cytotoxicity of perfluorododecanoic acid to neurons

Perfluorododecanoic acid (PFDoA), used in numerous commercial products, was recently demonstrated to accumulate in the brain more easily than other perfluorinated compounds and to cause cognitive deficits. In this study, pheochromocytoma 12 (PC12) cells were exposed to doses of PFDoA to explore the cytotoxicity of this compound to neurons. The results showed that treatment with PFDoA decreased PC12 cell viability dose-dependently. Treatment with 50 and 100 µM PFDoA significantly increased reactive oxygen species (p < 0.01) and malondialdehyde (p < 0.01) and decreased total antioxidant capacity (p < 0.05 and p < 0.01, respectively) in PC12 cells. The administration of 50 and 100 µM PFDoA led to a loss of mitochondrial membrane potential (MMP) (p < 0.05 and p < 0.01, respectively) in PC12 cells. The activity of caspase 3 was obviously increased (p < 0.05) in 100 µM PFDoA-treated PC12 cells. In general, the results demonstrated that PFDoA exposure could result in the disruption of MMP, which may contribute to the increase of oxidative stress and activation of the apoptotic signaling cascade in PC12 cells.

Model-based analysis of the uptake of perfluoroalkyl acids (PFAAs) from soil into plants

Perfluoroalkyl acids (PFAAs) bioaccumulate in crops, with uptake being particularly high for short-chain PFAAs that are constantly transported with transpiration water to aerial plant parts. Due to their amphiphilic surfactant nature and ionized state at environmental pH, predicting the partitioning behavior of PFAAs is difficult and subject to considerable uncertainty, making experimental data highly desirable. Here, we applied a plant uptake model that combines advective flux with measured partition coefficients to reproduce the set of empirically derived plant uptake and soil-partitioning data for nine PFAAs in red chicory, in order to improve the mechanistic understanding and provide new insights into the complex uptake processes. We introduced a new parameter for retarded uptake (R) to explain the slow transfer of PFAA across biomembranes of the root epidermis, which has led to low transpiration stream concentration factors (TSCFs) presented in literature so far. We estimated R values for PFAAs using experimental data derived for red chicory and used the modified plant uptake model to simulate uptake of PFAA into other crops. Results show that this semi-empirical model predicted PFAAs transport to shoots and fruits with good accuracy based on experimental root to soil concentration factors (RCF_dw) and soil to water partition coefficients (K_d) as well as estimated R values and plant-specific data for growth and transpiration. It can be concluded that the combination of rather low K_d with high RCF_dw and the absence of any relevant loss are the reason for the observed excellent plant uptake of PFAAs.

Occurrence, partition and environmental risk assessment of per- and polyfluoroalkyl substances in water and sediment from the Baiyangdian Lake, China

This work examined the contamination of poly- and perfluorinated compounds (PFASs) in the water and sediment of the Baiyangdian Lake. The total concentration of PFASs in the surface water varied from 140.5 to 1828.5 ng/L, and the highest concentration of PFASs were observed near the entrance of Fuhe river. The topmost contaminant was sodium perfluorohexanesulfonate (PFHxS) and perfluorooctanoic acid (PFOA) in the north and south of the Baiyangdian Lake respectively, which indicated different contamination sources. The total concentration of PFASs in the sediment varied from 0.48 to 30 ng/g, and the distribution of PFASs in the sediment was similar with that in the surface water. The concentrations of polyfluoroalkyl phosphoric diesters (diPAPs) were three to four orders of magnitude lower than those of perfluorocarboxylates (PFCAs) and PFSAs. Although the pore water and the surface water had similar ΣPFASs, the concentration of perfluorodecanoic acid (PFDA) in pore water was 1.4 to 4.4 times higher than that in surface water, and the concentration of perfluoropentanoic acid (PFPeA) in pore water was 20–70% that in surface water. The results of ecological risk assessment showed that the PFASs were currently of no immediate risk to the aquatic life.

Distribution of perfluoroalkyl substances (PFASs) in aquatic plant-based systems: From soil adsorption and plant uptake to effects on microbial community

This study systematically explored the distribution of perfluoroalkyl substances (PFASs) through soil adsorption and plant bioaccumulation in aquatic plant-based systems, derived from a surface flow constructed wetland (CW) planted with Typha angustifolia. The water-soil-plant systems were fortified with eight perfluoroalkyl subsntances (PFASs) at different concentrations. The potential for individual PFAS adsorption onto soil substrate and bioaccumulation in the plants increased with the increasing PFAS initial concentrations. Longer-chain PFASs exhibited higher affinity to soil substrate compared to shorter-chain PFASs. The highest concentration in the soil was observed for PFOS (51.3 ng g^-1), followed by PFHxS (9.39 ng g^-1), and PFOA (5.53 ng g^-1) at low PFAS level. The perfluoroalkyl chain length dependent trend was also seen in the roots with the highest individual PFAS concentration for PFOS (68.9 ng g^-1), followed by PFOA (18.5 ng g^-1) and PFHxS (13.4 ng g^-1). By contrast, shorter-chain PFASs were preferentially translocated from roots to shoots in Typha angustifolia. A significant (p < 0.05) positive correlation between bioaccumulation factor (BAF_plant/water) (whole plant) and perfluoroalkyl chain length was observed. PFASs content in the plant compartments increased with increasing PFAS concentrations in the soil. Mass balance analysis indicates that approximately 40.7-99.6% of PFAS mass added to the system was adsorbed onto the soil and bioaccumulated in the plant tissues of T. angustifolia. Soil adsorption played a vital role in PFAS mass distribution. The results of Illumina high-throughput sequencing show that the bacterial diversity decreased upon PFAS exposure. The most predominant phyla retrieved were Proteobacteria (24.7-39.3%), followed by Actinobacteria (4.2-41.1%), Verrucomicrobia (7.9-25.1%), Bacteroidetes (10.2-20.4%), Cyanobacteria (0.4-16.5%), and Firmicutes (1.1-6.4%). The PFAS enrichment caused the changes (p > 0.05) in the structure and composition of bacterial community. This study helps to gain insight into a better understanding of the potential for PFASs distribution in an aquatic plant-based system and the impact on dynamic of microbial community exposed to PFASs.

Perfluorobutanesulfonic Acid Disrupts Pancreatic Organogenesis and Regulation of Lipid Metabolism in the Zebrafish, Danio rerio

Following the phase-out of highly persistent perfluorosulfonates in the United States from non-stick and stain-resistant products in the early 2000s, perfluorobutanesulfonic acid (PFBS) has replaced these compounds as a primary surfactant. Measurements of PFBS in environmental and human samples have been rising in recent years, raising concerns about potential negative health effects. We previously found that embryonic exposures to a related compound, perfluorooctanesulfonic acid (PFOS), decreased pancreas length and insulin-producing islet area in zebrafish embryos (Danio rerio). The objective of this study was to compare the effects of PFBS exposures on pancreatic organogenesis with our previous PFOS findings. Dechorionated zebrafish embryos from two different transgenic fish lines (Tg[insulin:GFP], Tg[ptf1a:GFP]) were exposed to 0 (0.01% DMSO), 16, or 32 µM PFBS daily beginning at 1 day post fertilization (dpf) until 4 and 7 dpf when they were examined using fluorescent microscopy for islet area and morphology, and exocrine pancreas length. PFBS-exposed embryos had significantly increased caudal fin deformities, delayed swim bladder inflation, and impaired yolk utilization. Incidence of fish with significantly stunted growth and truncated exocrine pancreas length was significantly increased, although these two effects occurred independently. Islet morphology revealed an increased incidence of severely hypomorphic islets (areas lower than the 1st percentile of controls) and an elevated occurrence of fragmented islets. RNA-Seq data (4 dpf) also identify disruptions in regulation of lipid homeostasis. Overall, this work demonstrates that PFBS exposure can perturb embryonic development, energy homeostasis, and pancreatic organogenesis.

Occurrence of perfluoroalkyl substances in selected Victorian rivers and estuaries: An historical snapshot

This reconnaissance study was undertaken in 2012 to examine the occurrence of common perfluoroalkyl substances (PFAS), including perfluoroalkyl sulphonic acids and perfluoroalkyl carboxylic acids in rivers and estuaries in Port Philip Bay, Victoria, Australia. In total, 19 PFAS were screened in grab samples of water using a combination of solid phase extraction and liquid chromatography - mass spectrometry measurement techniques. Eighteen of the PFAS screened were observed in samples. The highest level of PFOS observed at a freshwater site was 0.045 μg/L; this concentration is approximately half the draft Australian 95% species protection level for total PFOS. The highest level of PFOA in the study (0.014 μg/L) was some four orders of magnitude lower than the draft Australian trigger value for PFOA (220 μg/L). However, none of the PFAS observed at the freshwater sites had research quotient (RQ) or toxicity unit (TU) values above 1 or -3, respectively. The highest concentration of PFOS observed at an estuarine site was 0.075 μg/L; the highest level of PFOA, 0.09 μg/L). There are no Australian marine water quality trigger values for PFAS, so potential risk was assessed using the European environment quality standards (EQS) adopted in EU Directive 2013/39/EU, RQ and TU methods. In that context, none of the PFAS observed at estuary sites had concentrations higher than the EU standards, or RQ above 1 or Log 10 TU above -3. Together these assessments suggest none of the PFAS screened would have posed an acute risk to organisms in the fresh or estuary waters studied at the time of sampling on an individual or collective basis. However, the detection of these PFAS in Victorian estuaries highlights that the issue is not just an issue for more densely populated countries in the northern hemisphere, but also potentially of concern in Australia. And, in that context, more sampling campaigns in Port Philip Bay are of paramount importance to assess the potential risk pose by these compounds to aquatic ecosystems.

Multi-compartment distribution of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in an urban catchment system

Ecotoxicological risks of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in surface waters are difficult to model because data on PFASs distribution in multiple compartments (sediments, suspended particles and aqueous phase) are difficult to predict. This study quantified the distribution of 21 PFASs including PFCAs: C6-C13 perfluoroalkyl carboxylates, C4, C6, C8 and C10 perfluoroalkane sulfonates, 5 perfluorooctane sulfonamide substances (FOSAMs, including EtFOSA, FOSA, MeFOSAA, EtFOSAA, FOSAA), 2 N-alkyl perfluoroalkane sulfonamidoethanols (MeFOSE and EtFOSE), bis (perfluorooctyl) phosphinic acid (C8/C8 PFPIA), and 5:3 fluorotelomer carboxylic acid (5:3 acid) between bulk water and suspended particles in water column, and pore water and benthic sediments from a tropical urban water body. The distribution of PFASs between sorbed and dissolved phase was largely dependent on the perfluoroalkyl chain length (N_CF2). PFCAs with N_CF2 > 11 and perfluorodecane sulfonate (PFDS, N_CF2 = 10) were found predominantly in the suspended particles and sediments. By contrast, short-chain PFASs (N_CF2 ≤ 7) were detected predominantly in the dissolved phase. Sediment acts as a sink for long-chain PFASs while short-chain PFASs are more easily transported via the aqueous phase. Compared with benthic sediments, suspended particles, especially those in the top water layer, carried much higher concentrations of PFASs (by a factor of >100), indicating the stronger sorption capability of suspended particles. The wide variation in PFAS concentrations in suspended particles (∑PFASs concentrations: < 26.8-1,284 ng/g d.w.) suggests that some suspended particles were preloaded with different concentrations of PFASs in the water column which could highly affect the distribution of PFASs in the aquatic environment. Pore water contained 1-2 times higher concentrations of PFASs (∑PFASs: <20.25-159.34 ng/L) than overlying bulk water (∑PFASs: <14.2-79.98 ng/L), indicating the accumulation of PFASs in pore water. Distribution coefficients (K_D) were calculated using paired solids concentration and dissolved concentration in both water and sediment column (K_D-SP and K_D-SED respectively) and were compared with values derived from a laboratory batch experiment. The averaged Log K_D-SP/Log K_D-SED showed significant positive correlation with N_CF2, except for short-chain PFASs (N_CF2 <5) which presented higher Log K_D values than estimated. The discrepancies found between K_D (Log K_D-SP > Log K_D -desorption > Log K_D -sorption > Log K_D-SED) suggest that the distribution of PFASs in the field, especially between suspended particles and bulk water could not be well represented by lab results and that using the water concentrations in the bottom layer for estimation of pore water concentrations could lead to bias results.

Where has the pollution gone? A survey of organic contaminants in Ho Chi Minh city / Saigon River (Vietnam) bed sediments

A wide range of persistent organic chemicals, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), some insecticides, as well as polybrominated diphenyl ethers (PBDEs) and some perfluoroalkyl substances (PFASs) were analyzed in 17 bed sediments collected along the Saigon River and at adjacent canal mouths from upstream to downstream in Ho Chi Minh City (Vietnam). Concentrations were rather low for PAHs, as well as for legacy PCBs and dichloro-diphenyl-trichlorethane and metabolites (DDTs), or below detection limits for several PFASs and all PBDEs measured. Several insecticides (chlorpyrifos-ethyl, and the pyrethroids cypermethrin and λ-cyhalothrin) displayed rather high concentrations at a few sites within the city. There was no distinct upstream - downstream trend for PAHs, (DDTs) or PCBs. Although adjacent canal sediments tended to be more contaminated than Saigon River sediments, the differences were not significant. Emissions are almost certainly substantial for PAHs, and probably also for other contaminants such as PBDEs and some PFASs. During the dry season, contaminants are presumably stored in the city, either in canals or on urban surfaces. Heavy rainfall during the monsoon period carries away contaminated particle flows into the canals and then the Saigon River. The strong tidal influence in the river channel hinders the accumulation of contaminated particles. Contaminated deposits should accordingly be investigated further downstream in depositional environments, such as the mangrove.

Assessing bioaccumulation behaviour of hydrophobic organic contaminants in a tropical urban catchment

The bioaccumulation behaviour of halogenated flame retardant (HFRs), synthetic musks (SMs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in plankton, invertebrates and fish was assessed in an urban catchment in Singapore which is a tropical island country highly populated. The studied contaminants ranged widely in physical-chemical properties, with K_OW values ranging between approximately 10³-10¹¹. BDE-47 and dechlorane plus (DPs) were the predominant HFRs, while galaxolide (HHCB) and tonalide (AHTN) were the predominant synthetic musk compounds in biota from the studied freshwater system. Concentrations of organochlorine contaminants such as chlordanes, DDE, DDD, PCB 138 and PCB 153 were generally higher than those of the HFRs and SMs. On a wet weight basis, bioaccumulation factors (BAFs) of the current use HFRs were in some cases higher than the bioaccumulation criteria value of 5000 L/kg wet weight. Conversely, BAFs of SMs were found to be less than the 5000 L/kg guideline. Lipid adjusted BAFs (L/kg lipid) of the studied contaminants varied among the different aquatic species, which is likely due to organism trophic level and metabolic transformation capacity differences. BAFs were highly correlated with the chemical K_OW values. For fish, log BAFs of the studied contaminants increased with increasing log K_OW, between a log K_OW range of approximately 3-7, after which BAFs subsequently decreased. A similar relationship was observed for BAFs in the studied invertebrates. For plankton, a simple linear regression was observed between log BAF and log K_OW over the target analyte K_OW range (log K_OW's between 3-11). Predicted BAF values derived from a mechanistic bioaccumulation model for hydrophobic organic contaminants were generally consistent with the observed BAFs. However, in some cases the model substantially overestimated bioaccumulation potential based on the chemical's hydrophobicity, which may be due to a high degree of biotransformation of those compounds. The study provides important information regarding bioaccumulation potential of several emerging organic contaminants of concern.

Tracing perfluoroalkyl substances (PFASs) in soils along the urbanizing coastal area of Bohai and Yellow Seas, China

With the shift of fluorine chemical industry from developed countries to China and increasing demand for fluorine chemical products, occurrence of perfluoroalkyl substances (PFASs) in production and application areas has attracted more attention. In this study, 153 soil samples were collected from 21 cities along the urbanizing coastal area of the Bohai and Yellow Seas. PFASs in this area were relatively higher, compared with other study areas. The concentrations ranged from 2.76 to 64.0 ng g^-1, and those in most sites were between 2.76 and 13.9 ng g^-1, with a predominance of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Among the 21 coastal cities, contaminations of PFASs in Zibo, Nantong and Binzhou were elevated, which was likely affected by local fluorine chemical plants, equipment manufacturing and chemical industry, respectively. The total emissions of PFOA and PFOS were similar, with amount of 4431 kg and 4335 kg, respectively. Atmospheric deposition was the largest source, accounting for 93.2% of total PFOA and 69.6% of PFOS, respectively. In addition, due to application of aqueous film-forming foams (AFFFs) and sulfluramid, disposal of sewage sludge and stacking of solid waste, emission of PFOA and PFOS to soil was 1617 kg, accounting for 9.29% of the whole China. In general, pollution in Jiangsu, Shandong and Tianjin was more serious than those in Liaoning and Hebei, which was consistent with industrialization level and size of industrial sectors emitting PFASs.

Occurrence and Fate of Benzophenone-Type UV Filters in a Tropical Urban Watershed

The study investigated the occurrence and fate of seven benzophenone-type UV filters (i.e., 2,4-dihydroxybenzophenone (2,4OH-BP), 2,2',4,4'-tetrahydroxybenzophenone (2,2',4,4'OH-BP), 2-hydroxy-4-methoxybenzophenone (2OH-4MeO-BP), 2,2'-Dihydroxy-4,4'-dimethoxybenzophenone (2,2'OH-4,4'MeO-BP), 2,2'-dihydroxy-4-methoxybenzophenone (2,2'OH-4MeO-BP), 4-hydroxybenzophenone (4OH-BP), and 4,4'-dihyroxybenzophenone (4DHB)) in a tropical urban watershed consisting of five major tributaries that discharge into a well-managed basin. Total benzophenone concentrations (∑C_BPs) varied from 19-230.8 ng L^-1 in overlying bulk water, 48-115 ng L^-1 in pore water, 295-5813 ng g^-1 dry weight (d.w.) in suspended solids, and 6-37 ng g^-1 d.w. in surficial sediments, respectively. The tributaries (∑C_BPs: 19-231 ng L^-1) were the main source of benzophenone compounds entering the basin (∑C_BPs: 20-81 ng L^-1). In the water column, the vertical concentration profile in the aqueous phase was uniform while concentrations in the suspended solids decreased with depth. Different distribution profiles were also identified for benzophenones in suspended solids and sediments. A preliminary risk assessment suggested that the seven BPs were unlikely to pose ecotoxicological risks to local aquatic organisms except for 2OH-4MeO-BP in the case of an intermittent release.

Immunotoxicity in green mussels under perfluoroalkyl substance (PFAS) exposure: Reversible response and response model development

The immunotoxicity of 4 commonly detected perfluoroalkyl substances (PFASs), namely, perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) was investigated by measuring biomarkers of the immune profile of green mussels, Perna viridis. The biomarkers included neutral red retention, phagocytosis, and spontaneous cytotoxicity, all of which were tested on mussel hemocytes. Hemocytes are an important component of the invertebrate immune system. We found that exposure to PFASs could lead to reduced hemocyte cell viability and suppress immune function by up to 50% of normal performance within the experimental exposure range. The results indicate that PFASs have an immunotoxic potential and thus could pose severe health risks to aquatic organisms. The reported immunotoxicity is likely to result from the compounds' direct and indirect interactions with the hemocyte membrane, and therefore likely to affect the functionality of these cells. The immunotoxic response was found to be related to the organism's burden of PFASs, and was reversible when the compounds were removed from the test organisms. Based on this relationship, models using an organism's PFAS concentration and bioaccumulation factor (BAF) as the independent variables were established to quantify PFAS-induced immunotoxicity. The models help us to gain a better understanding of the toxic mechanism of PFASs, and provide a tool to evaluate adverse effects for the whole group of compounds with one mathematical equation. Environ Toxicol Chem 2018;37:1138-1145. © 2018 SETAC.

Occurrence and distribution of halogenated flame retardants in an urban watershed: Comparison to polychlorinated biphenyls and organochlorine pesticides

Due to restrictions on polybrominated diphenyl ethers (PBDEs), market demand for alternative flame retardants is projected to increase, worldwide. Information regarding the environmental behavior of these compounds is limited. The present study involved field measurements of several alternative halogenated flame retardants (HFRs), along with PBDEs and legacy persistent organic pollutants (POPs) in surface water, bottom sediments and suspended particulate matter (SPM) within a highly urbanized watershed in Singapore. Several alternative HFRs were detected in water and sediments. Dechlornane Plus stereoisomers (syn- and anti-DP) were detected in all samples, exhibiting relatively high concentrations in water, sediments and SPM. The maximum syn-DP concentrations in water, sediments and SPM were 24.30 ng/L, 2.48 ng/g dry wt. and 7774 ng/g dry wt., respectively. 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromotoluene (PBT), hexabromobenzene (HxBBz) and tetrabromoethylcyclohexane (TBECH) were routinely detected. PBDE concentrations were relatively low and often non-detectable. Polychlorinated biphenyl (PCB) concentrations ranged from 0.017 to 8.37 ng/L in water, 9.86-27.92 ng/g dry wt. in SPM, and 6.48-212.3 ng/g dry wt. in sediments. Congener and isomer patterns suggested no recent inputs of PBDEs or dichlorodiphenyltrichloroethane (DDT). Rainfall was found to be an important factor influencing temporal and spatial patterns of DPs, BTBPE, PBDEs and some organochlorines in surface water. Land use index was found to be important for several organochlorines, but not HFRs. The observed sediment-water partitioning behavior of the studied HFRs and legacy POPs was highly dependent on chemical hydrophobicity. The data demonstrate that the studied HFRs have a relatively high affinity for SPM and bottom sediments. For example, the log K_OC,OBS for TBECH, syn-DP and anti-DP and BTBPE in bottom sediments ranged between 8.1 and 9.6. The findings will aid future studies regarding fate, transport and bioaccumulation of these current-use contaminants of concern.

Perfluoroalkyl and polyfluoroalkyl substances removal in a full-scale tropical constructed wetland system treating landfill leachate

Landfill leachate is often an important source of emerging organic contaminants including perfluoroalkyl and polyfluoroalkyl substances (PFASs) requiring proper treatment to protect surface water and groundwater resources. This study investigated the occurrence of PFASs in the leachate of a capped landfill site in Singapore and the efficacy of PFASs removal during flow through a constructed wetland (CW) treatment system. The CW treatment system consists of equalization tank, aeration lagoons, sedimentation tank, reed beds and polishing ponds. Target compounds included 11 perfluoroalkyl acids (PFAAs) (7 perfluoroalkyl carboxylic acids (PFCAs) and 4 perfluoroalkane sulfonates (PFSAs)) and 7 PFAA precursors. Although total PFASs concentrations in the leachate varied widely (1269 to 7661 ng/L) over the one-year sampling period, the PFASs composition remained relatively stable with PFCAs consistently being predominant (64.0 ± 3.8%). Perfluorobutane sulfonate (PFBS) concentrations were highly correlated with total PFASs concentrations and could be an indicator for the release of PFASs from this landfill. The release of short-chain PFAAs strongly depended on precipitation whereas concentrations of the other PFASs appeared to be controlled by partitioning. Overall, the CW treatment system removed 61% of total PFASs and 50-96% of individual PFASs. PFAAs were removed most efficiently in the reed bed (42-49%), likely due to the combination of sorption to soils and sediments and plant uptake, whereas most of the PFAA precursors (i.e. 5:3 fluorotelomer carboxylate (5:3 acid), N-substituted perfluorooctane sulfonamides (N-MeFOSAA and N-EtFOSAA)) were removed in the aeration lagoon (>55%) by biodegradation. The sedimentation tank and polishing ponds were relatively inefficient, with only 7% PFASs removal.

Influence of Environmental Factors on the Fate of Legacy and Emerging Per- and Polyfluoroalkyl Substances along the Salinity/Turbidity Gradient of a Macrotidal Estuary

This study aimed at bridging knowledge gaps regarding the land-sea transport of per- and polyfluoroalkyl substances (PFASs) through riverine discharge into coastal waters. The present survey was conducted in the Gironde estuary (southwestern France) where PFASs were ubiquitously detected albeit at low levels. Emerging PFASs such as fluorotelomer sulfonates or polyfluoroalkyl phosphate diesters accounted for a relatively minor proportion of ∑PFASs, while perfluorooctanesulfonate, perfluorohexanesulfonate, and perfluorohexanoate were the predominant congeners. Multiple linear regressions provided insights into the relative influence of factors controlling PFAS sediment levels. In that respect, the organic carbon fraction (strongly correlated to sediment grain size) appeared as a more important controlling factor than black carbon or distance from upstream sources for long-chain perfluoroalkyl acids. In the maximum turbidity zone (suspended solids up to 2600 mg L^-1), the particle-associated fraction was almost consistently >50% for long-chain perfluoroalkyl carboxylates and sulfonates (≥C8 and ≥ C6, respectively). Empirical models of K_D partitioning coefficients were derived by integrating, for the first time, both particle-concentration and salting-out effects. These results represent significant progress toward the development of numerical transport models integrating both PFAS partitioning and 3D-hydrosedimentary dynamics, with a view to estimate PFAS mass budgets at the land-sea interface.