Prenatal exposure to poly/perfluoroalkyl substances and risk for congenital heart disease in offspring

Congenital heart disease (CHD) is the most prevalent congenital malformation worldwide, and the association between per- and polyfluoroalkyl substances (PFASs) exposure and CHD in population has only received limited study. Therefore, we conducted a multicenter case-control study to explore the associations between prenatal exposure to individual PFASs, and also a PFAS mixture, and CHD risk, including 185 CHDs and 247 controls in China from 2016 to 2021. Thirteen PFASs in maternal plasma were quantified using liquid chromatography-tandem mass spectrometry. Logistic regression and two multipollutant models (Bayesian kernel machine regression [BKMR] and quantile g-computation [qgcomp]) were used to assess the potential associations between any individual PFAS, and also a PFAS mixture, and CHD risk. After adjusting for potential confounders, logistic regression indicated significant associations between elevated levels of perfluorononanoic acid (odds ratio [OR]= 1.30, 95% confidence intervals [CI]: 1.07-1.58), perfluorodecanoic acid (OR=2.07, 95%CI: 1.32-3.26), and perfluoroundecanoic acid (OR=2.86, 95%CI:1.45-5.65) and CHD risk. The BKMR model and qgcomp approach identified that a significant positive association between the PFAS mixture and risk for CHD. These findings provide essential evidence that there is indeed a health crisis associated with PFASs and that it is linked to CHD.

Distribution of per- and polyfluoroalkyl substances in blood, serum, and urine of patients with liver cancer and associations with liver function biomarkers

Studies have shown that per- and polyfluoroalkyl substances (PFASs) may be hepatotoxic in animals or humans. However, data on clinical epidemiology are very limited. In this study, 21 PFASs were determined in patients with liver diseases, with the highest median concentrations detected in the serum sample (26.7 ng/mL), followed by blood (10.7 ng/mL) and urine (5.02 ng/mL). Higher total PFAS concentrations were found in hepatocellular carcinoma (HCC) patients compared to non-HCC patients, with significant discrepancies in serum and blood samples. Besides, significant correlations were also found among PFAS concentrations and age, gender, body mass index (BMI), and liver function biomarkers levels. For example, PFAS concentrations are significantly higher in males than in females; Several serum PFASs concentrations increase with age and BMI, while the serum perfluorohexane sulfonic acid (PFHxS) concentrations are negatively correlated with age. In addition, multiple regression models adjusted for age, gender and BMI found that increased serum perfluorobutane sulfonic acid (PFBS), perfluoroheptane sulfonic acid (PFHpS) and perfluorohexylphosphonic acid (PFHxPA) conentrations are correlated with elevated alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alpha-fetoprotein (AFP) (p < 0.05). Our results provide epidemiological support for the future study on the potential clinical hepatotoxicity of PFAS.

Distribution, sources and ecological risks of per- and polyfluoroalkyl substances in overlying water and sediment from the mangrove ecosystem in Hainan Island, China

Since data on Per- and polyfluoroalkyl substances (PFASs) in mangrove ecosystems are very limited. This study investigated the occurrence, distribution, sources, and ecological risk of 24 PFASs in the overlying waters and sediments of mangrove systems in Hainan Island, China. The concentration levels of PFASs in water and sediment ranged from 6.3 to 35.3 ng/L and from 0.33 to 10.2 ng/g dw, respectively. In terms of spatial distribution, firstly, the mangrove forests in Haikou and Sanya contained higher levels of PFASs; secondly, the eastern region contained higher levels of PFASs than the western region. The reasons for this may be related to the population size and development level of the region. For the organic carbon normalized sediment-water partition coefficient (log Koc), the results showed that log Koc decreased with increasing carbon chains for short-chain PFASs (with ≤6 CF2 units) and increased with increasing carbon chains for long-chain PFASs (with ˃6 CF2 units). Principal Component Analysis (PCA) and correlation analysis were employed to pinpoint specific origins of PFASs, namely firefighting, metal plating, food packaging, textiles, and fluoropolymer manufacturing. The risk quotient (RQ) values of PFASs in mangrove ecosystems on Hainan Island were all <1, but the existence of potential risks cannot be excluded. Hence, further investigations related to the bioaccumulation effects of PFASs in organisms in mangrove forests should be conducted to gain a more comprehensive understanding of their environmental behavior.

The occurrence, spatial distribution, and well-depth dependence of PFASs in groundwater from a reclaimed water irrigation area

With the growing development of modern agriculture and industry, groundwater is facing more and more complex contaminants. One such contaminant is per- and polyfluoroalkyl substances (PFASs), which pose a potential risk to human health, particularly for those who rely on groundwater as their primary source of drinking water. In this study, we conducted a comprehensive investigation on the occurrence, spatial distribution, and source apportionment of PFASs in shallow (<60 m) and deep (>80 m) groundwater samples from a reclaimed water irrigation area in Beijing's suburbs. Our results showed that the average total PFAS concentration (∑10PFAS) for all samples was 10.55 ± 7.77 ng/L, ranging from 1.05 to 34.28 ng/L. The dominant congeners were PFBA, PFOA, and PFBS. No significant linear relationship was observed between PFAS concentrations and the well depth. However, the averaged ΣPFASs in groundwater were highest in the uppermost layer and declined sharply to a few ng/L in the deep aquifer below 80 m. PFASs showed elevated concentration in shallow aquifers in 9 out of 11 paired wells, indicating an overall descending trend of PFASs with increasing aquifer depth. The spatial distribution of PFASs was highly heterogeneous and showed different patterns in shallow and deep groundwater, which may be related to the complicated attenuation behavior of PFAS compounds when they transport and diffuse through overlapping aquifer layers. The influence of the landfill on groundwater PFASs was most pronounced within a 5 km radius. Source apportionment results indicated that reclaimed water irrigation is the main non-point source of PFASs in shallow groundwater. In contrast, deep groundwater is primarily subject to point sources and lateral recharge flow. This investigation of PFASs in shallow and deep wells provides a foundation for further exploration of PFASs transportation and risk prevention in regions where groundwater is a major water resource for domestic and industrial development.

First determination on two kinds of microplastic-air partition coefficients of seven per- and polyfluoroalkyl substances under environmentally relative conditions: Experiment measurement and model prediction

Microplastics (MPs) in the environment are the sink and vector of organic contaminants, including per- and polyfluoroalkyl substances (PFASs). Although PFASs are low- and non-volatile compounds, they have the potential to partition and diffuse from MP into the gas phase in the environmental functions. Herein, the MP-air partition coefficient (KPA) of seven PFASs was measured using a solid-fugacity meter. The PFAS KPA values in two MPs (high-density polyethylene (HDPE) and thermoplastic polyurethane (TPU)) were determined under different times, temperatures, and relative humidities (RH), and a model was developed to predict the PFAS KPA values based on the measured data. The results showed that the KPA of PFASs increased with the prolonged partition time until 90 mins, and higher temperature and RH facilitated the distribution of PFASs in MPs into the air phase, leading to smaller KPA values. Moreover, the derived equation for predicting PFAS log KPA values was robust with 0.79 of an adjusted square of correlation coefficient (R2adjusted = 0.79) and 0.35 of root mean squared error (RMSE = 0.35). These findings provided the first knowledge for understanding the partition behavior and fate of PFASs in the MP-air microenvironment.

Quantification and characterization of PFASs in suspended particulate matter (SPM) of German rivers using EOF, dTOPA, (non-)target HRMS

In this study, we compare analytical methods for PFAS determination-target analysis, non-target screening (NTS), direct total oxidizable precursor assay (dTOPA) and extractable organically bound fluorine (EOF). Therefore, suspended particulate matter (SPM) samples from German rivers at different locations in time series from 2005 to 2020 were analyzed to investigate temporal and spatially resolved trends. In this study 3 PFAS mass balances approaches were utilized: (i) PFAA target vs. PFAS dTOPA, (ii) PFAS target vs. EOF and (iii) PFAS target vs. PFAS dTOPA vs. organofluorines NTS vs. EOF. Mass balance approach (i) revealed high proportions of precursor substances in SPM samples. For the time resolved analysis an increase from 94% (2005) to 97% in 2019 was observable. Also for the spatial resolved analysis precursor proportions were high with >84% at all sampling sites. Mass balance approach (ii) showed that the unidentified EOF (uEOF) fraction increased over time from 82% (2005) to 99% (2019). Furthermore, along the river courses the uEOF increased. In the combined mass balance approach (iii) using 4 different analytical approaches EOF fractions were further unraveled. The EOF pattern was fully explainable at the sampling sites at Saar and Elbe rivers. For the time resolved analysis, an increased proportion of the EOF was now explainable. However, still 27% of the EOF for the time resolved analysis and 25% of the EOF for the spatial resolved analysis remained unknown. Therefore, in a complementary approach, both the EOF and dTOPA reveal unknown gaps in the PFAS mass balance and are valuable contributions to PFAS risk assessment. Further research is needed to identify organofluorines summarized in the EOF parameter.

PFASs: What can we learn from the European Human Biomonitoring Initiative HBM4EU

Per- and polyfluoroalkyl substances (PFASs) were one of the priority substance groups selected which have been investigated under the ambitious European Joint programme HBM4EU (2017-2022). In order to answer policy relevant questions concerning exposure and health effects of PFASs in Europe several activities were developed under HBM4EU namely i) synthesis of HBM data generated in Europe prior to HBM4EU by developing new platforms, ii) development of a Quality Assurance/Quality Control Program covering 12 biomarkers of PFASs, iii) aligned and harmonized human biomonitoring studies of PFASs. In addition, some cohort studies (on mother-child exposure, occupational exposure to hexavalent chromium) were initiated, and literature researches on risk assessment of mixtures of PFAS, health effects and effect biomarkers were performed. The HBM4EU Aligned Studies have generated internal exposure reference levels for 12 PFASs in 1957 European teenagers aged 12-18 years. The results showed that serum levels of 14.3% of the teenagers exceeded 6.9 μg/L PFASs, which corresponds to the EFSA guideline value for a tolerable weekly intake (TWI) of 4.4 ng/kg for some of the investigated PFASs (PFOA, PFOS, PFNA and PFHxS). In Northern and Western Europe, 24% of teenagers exceeded this level. The most relevant sources of exposure identified were drinking water and some foods (fish, eggs, offal and locally produced foods). HBM4EU occupational studies also revealed very high levels of PFASs exposure in workers (P95: 192 μg/L in chrome plating facilities), highlighting the importance of monitoring PFASs exposure in specific workplaces. In addition, environmental contaminated hotspots causing high exposure to the population were identified. In conclusion, the frequent and high PFASs exposure evidenced by HBM4EU strongly suggests the need to take all possible measures to prevent further contamination of the European population, in addition to adopting remediation measures in hotspot areas, to protect human health and the environment. HBM4EU findings also support the restriction of the whole group of PFASs. Further, research and definition for additional toxicological dose-effect relationship values for more PFASs compounds is needed.

High density polyethylene (HDPE) and thermoplastic polyurethane (TPU) wristbands as personal passive samplers monitoring per- and polyfluoroalkyl substances (PFASs) exposure to postgraduate students

Per- and polyfluoroalkyl substances (PFASs) present adverse effects for human health, which result in strong needs for reliable tools monitoring personal exposure to PFASs. This study manufactured two wristbands of high density polyethylene (HDPE) and thermoplastic polyurethane (TPU), and used the wristbands to monitor PFASs personal exposure. The analytical method was developed to measure 32 PFASs in the paired HDPE and TPU wristbands worn by 60 postgraduates. Twenty-nine of 32 PFASs were detected and hexafluoropropylene oxide dimer acid (HFPO-DA) was predominant individual PFASs with median concentrations of 337 and 554 pg/g for HDPE and TPU wristbands respectively. The gender and grade of students had moderate effects on PFASs distribution in the wristbands. Higher PFASs levels were determined in the two wristbands worn by the male students compared to the females, and the greatest PFASs concentration was observed in the wristbands worn by the first-year postgraduates, follow by second- and third-year postgraduates. Additionally, significant correlations between paired HDPE and TPU wristbands were observed for perfluorobutanoic acid (PFBA), perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonic acid (PFOS), and HFPO-DA. These results suggest that HDPE and TPU wristbands can be used as effective tools for monitoring personal PFAS exposure.

Automated and fast online method for simultaneously determining a broad spectrum of per- and polyfluoroalkyl substances in a small volume of cerebrospinal fluid

Per- and polyfluoroalkyl substances (PFASs) are potentially neurotoxic compounds. Levels of PFASs in cerebrospinal fluid (CSF) could directly reflect their potential harm to the central nervous system. Because of the variety of PFASs and the rarity of CSF, there is an urgent need to establish a rapid online method to detect a broad spectrum of PFASs accurately and simultaneously by consuming a small amount of CSF. In this study, we developed a fast and automated method to analyze 52 PFASs in human CSF samples using online TurboFlow ultra-high-performance liquid chromatography-tandem mass spectrometry. Our method offered excellent matrix-matched standard curve linearity (correlation coefficient > 0.99), good limits of quantitation (MLOQs) (0.01 to 0.08 ng mL^-1), satisfactory accuracy (recoveries of 74.6%-119.1%) and precision (relative standard deviations of 1.4%-13.2%), small sample amount consumption (50 μL), and fast analysis time (18 min per sample) without complex sample pretreatment procedures. These are advantageous for the high throughput screening of PFASs in environmental epidemiology studies. Repeated freeze-thaw experiments showed that it was better to perform the analytical process soon as possible after sample collection. The established method was used to analyze PFASs in 60 people. Short-chain PFASs, perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), and novel PFASs [sodium 2-(N-ethylperfluorooctane-1-sulfonamido)ethyl phosphate (SAmPAP), perfluoroethylcyclohexanesulfonate (PFECHS), and perfluoro-3, 7-dimethyloctanoic acid (P37DMOA)] were reported in CSF for the first time. PFBA and PFPeA were detected in all samples with mean concentrations of 0.24 and 0.22 ng mL^-1, respectively. We also calculated the blood-brain barrier transmission efficiency of PFASs (R_PFAS), and the mean R_PFBA value was above 1, which indicated that PFBA might transfer from serum to CSF.

Associations of per- and polyfluoroalkyl substances and their alternatives with bone mineral density levels and osteoporosis prevalence: A community-based population study in Guangzhou, Southern China

BACKGROUND

Evidence concerning associations of per- and polyfluoroalkyl substances (PFASs) exposure with bone mineral density (BMD) and osteoporosis is scarce. Additionally, no study has examined the effects of PFAS isomers and alternatives on bone health.

OBJECTIVES

To evaluate the associations of PFASs and PFAS alternatives with BMD levels and osteoporosis prevalence.

METHODS

A total of 1260 healthy adults from southern China were enrolled. Serum concentrations of 32 legacy PFASs, PFAS isomers, and alternatives were measured using modified liquid chromatography-tandem mass spectrometry. Logistic and linear regression models were applied to evaluate the associations of PFASs with osteoporosis prevalence and BMD levels, respectively, adjusting for confounding factors. We performed stratified analyses to assess potential effect modifications of age and sex. We further used sensitivity analyses to testify the robustness of the main findings.

RESULTS

There were 204 (16.2 %) participants diagnosed with osteoporosis. Eleven of the studied PFASs (i.e., PFHpA, PFOA, PFBS, PFHpS, total-PFHxS, n-PFHxS, br-PFHxS, br-PFOS, 1m-PFOS, Σ3 + 4 + 5m-PFOS, and 6:2 Cl-PFESA) showed significant and inverse associations with BMD levels (mean differences ranged from -6.47 to -26.07 per one ln-unit increase in the PFASs). Additionally, we observed that each one ln-unit increase in PFHpA was significantly associated a 23 % (OR = 1.23, 95 % CI = 1.04, 1.45) greater odds of osteoporosis. The above associations were consistent in several sensitivity analyses we performed. Stratified analyses showed stronger associations among women and younger compared to their counterparts.

CONCLUSIONS

Our findings suggested that greater PFAS exposure is associated with poorer bone health, especially in women and younger people.

A critical review of the occurrence, fate and treatment of per- and polyfluoroalkyl substances (PFASs) in landfills

The aim of this critical review is i) to summarize the occurrence of Per- and polyfluoroalkyl substances (PFASs) in landfills; ii) to outline the environmental fate and transport of PFASs in landfills; iii) to compare the treatment technologies of PFASs in landfill leachate and remediation methods of PFASs in surrounding groundwater; iv) to identify the research gaps and suggest future research directions. In recent years, PFASs have been detected in landfills around the world, among which Perfluoroalkyl acids (PFAAs) especially Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonic acid (PFOS) are mostly studied due to their long-term stability. Short-chain PFASs (<8 carbons) are more common than long-chain PFASs (≧8 carbons) in landfill leachate. PFASs in landfill leachate are eventually transported to the surrounding groundwater, surface water and soil. Some PFASs evaporate from landfills to the ambient air. To avoid the environmental and health risks of PFASs in landfills, new technologies and combined use of existing technologies have been implemented to treat PFASs in landfill leachate. Integrated remediation methods are applied to control the diffusion of PFASs in groundwater surrounding landfills. In future, the mechanisms of PFAAs precursors degradation, the correlation among PFASs in different environmental media around landfills, as well as the environmental behavior and toxic effect of combined pollutants together with PFASs in landfill leachate and surrounding groundwater should be studied.

Screening of structural and functional alterations in duckweed (Lemna minor) induced by per- and polyfluoroalkyl substances (PFASs) with FTIR spectroscopy

As a class of common emerging pollutants, per- and polyfluoroalkyl substances (PFASs) and their alternatives have been widely detected in various environmental matrices, exhibiting a great threat to the ecological environment and human health. Nevertheless, changes in biomolecular structure and function of duckweed caused by PFASs and their alternatives remain unknown thus far. Herein, the effects of four PFASs, including two common legacy PFASs (perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)) and two PFASs alternatives (perfluorobutane sulfonic acid (PFBS) and 1H,1H,2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)) on duckweed (Lemna minor) at biochemical level were investigated with Fourier transform infrared spectroscopy (FTIR). Although no obvious inhibitions were observed in the growth of L. minor with PFASs exposure at three levels of 1 μg L^-1, 100 μg L^-1, and 10 mg L^-1, significant structural and functional alterations were induced at the biochemical level. In response to PFASs exposure, lipid peroxidation, proteins aggregation and α-helix to β-sheet transformation of the protein conformation, as well as changes of DNA conformations were detected. Moreover, alterations in lipid, protein, and DNA were proved to be concentration-related and compound-specific. Compared to the two legacy PFASs (PFOS and PFOA), alternative ones exhibited greater effects on the biological macromolecules of L. minor. The findings of this study firstly reveal structural and functional alterations in L. minor induced by PFASs exposure, providing further understanding of their toxicity effects.

Glioma is associated with exposure to legacy and alternative per- and polyfluoroalkyl substances

Data on the occurrences of legacy and alternative per- and polyfluoroalkyl substances (PFASs) in glioma are scarce. It remains unclear if PFASs exposure is related to the prevalence of glioma. A total of 137 glioma and 40 non-glioma brain tissue samples from patients recruited from the Nanfang Hospital, South China were analyzed for 17 PFAS compounds. Perfluorohexanoic acid, perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorooctane sulfonamide (FOSA), and 6:2 chlorinated polyfluorinated ether sulfonate were frequently detected (> 60 %) in glioma. The total concentrations (range; median) of 17 PFASs in glioma (0.20-140; 3.1 ng g^-1) were slightly higher than those in non-glioma (0.35-32; 2.2 ng g^-1), but without statistical significance. The PFAS concentrations in males were statistically higher (p < 0.05) than those in females. Elevated glioma grades were associated with higher concentrations of PFOA, PFOS, and FOSA. Positive correlations were observed between PFAS concentrations (especially for PFOA) and Ki-67 or P53 expression, pathological molecular markers of glioma. Our findings suggested that exposure to PFASs might increase the probability to develop glioma. This is the first case study demonstrating associations between PFASs exposure and brain cancer. More evidences and potential pathogenic mechanisms warranted further investigations.

Monitoring and ecological risk assessment of contaminants in freshwater bodies by bioindicators in China: a proposed framework

Bioindicators can provide pollution information with longer temporal duration and larger spatial scale. It is an ideal strategy for long-term monitoring of bioaccumulative contaminants. Bioindicator monitoring has been widely used; however, there were seldom detailed studies about bioindicator methodology in literature. The present study proposed a bioindicator framework suitable for the local conditions of China, including selection of bioindicator species, evaluation of impact factors, and derivation of threshold values using per- and polyfluoroalkyl substances (PFASs) as an example. The criteria that proper bioindicator species should meet and the procedure how the bioindicator species is selected were proposed, under which crucian carp (Carassius auratus) was selected as the local bioindicator for studied PFASs. Several factors which may affect accumulation of contaminants in bioindicators were suggested to produce reliable and comparable results. Derivation method of bioindicator thresholds for ecological risk assessment of aquatic ecosystems was firstly developed. The long-term and short-term ecological thresholds of perfluorooctanesulfonate using crucian carp as bioindicator are 3.329 and 1.402 μg/g wet weight respectively. Using the long-term thresholds derived from chronic toxicity data and the accumulative concentrations of contaminants obtained by bioindicator results, the bioindicator monitoring can be used for long-term ecological risk surveillance. The threshold derivation method can extend the application of bioindicator monitoring from the occurrence study to ecological risk surveillance, which is especially important for China who has made progresses on regular contaminant control and starts to be concerned about the ecological risks of the emerging contaminants. The framework can be used to create national and regional long-term freshwater bioindicator monitoring programs, with the purposes of ecological risk assessment, occurrence and temporal trend study, pollution source identification, international convention fulfillment, retrospective study, etc. The bioindicator framework will benefit the aquatic environmental safety and the hazardous chemical management in China.

Target analysis and suspect screening of per- and polyfluoroalkyl substances in paired samples of maternal serum, umbilical cord serum, and placenta near fluorochemical plants in Fuxin, China

The levels of legacy per- and polyfluoroalkyl substances (PFASs) have been growing in the environmental matrices and blood of residents living around the fluorochemical industrial park (FIP) in Fuxin of China over the past decade. Although some recent studies have reported occurrence of novel PFAS alternatives in biotic and abiotic matrices near fluorochemical facilities worldwide, little is known about novel PFAS congeners in maternal sera, umbilical cord sera, and placentas from the female residents close to the FIP and their related health risks. In this study, 50 paired samples of maternal and cord serum as well as placenta were derived from Fuxin pregnant women at delivery, and 21 target analytes of legacy PFASs in all the samples were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), revealing that PFBS, PFBA, and PFOA were the dominant PFAS contaminants observed in the whole samples. Based upon the suspect screening through high-resolution mass spectrometry (HRMS), 49 novel PFASs assigned to 11 classes were further identified in the Fuxin samples, of which, 20 novel congeners in 4 classes were reported in human blood and placentas for the first time. Moreover, the coefficients for mother-placenta transfer (R_m/p), placenta-newborn transfer (R_p/n), and mother-newborn transfer (R_m/n) of legacy PFASs could be calculated with median values of 1.7, 1.1, and 2.0, respectively, and R_m/p, R_p/n, and R_m/n for each novel PFAS identified were also estimated with the median values of 0.9, 1.2, and 0.8 individually. Accordingly, novel PFASs contributed 90% of all the legacy and novel PFASs in maternal sera and even occupied 96% of the whole PFASs in both placentas and cord sera. In addition, significant associations were determined among the neonate birth outcomes and serum concentrations of thyroid hormone, sex hormone, and glucocorticoid, together with the levels of certain legacy and novel PFASs in cord sera.

Chemical-specific determinants for pre-conceptional exposure to emerging and legacy per- and polyfluoroalkyl substances

The exposure of preconception women to per- and polyfluoroalkyl substances (PFASs) could negatively affect her reproductive health. However, chemical-specific determinants for pre-conceptional exposure to PFASs, particularly the emerging ones, remain poorly understood. In the present study, it was found that the total PFAS concentration ranged from 8.9 to 440.3 ng/mL (median: 49.6 ng/mL) in 1060 preconception women. The PFAS exposure profile was dominated by PFOA (16.8 ng/mL), followed by PFOS (13.3 ng/mL), 6:2 Cl-PFESA (8.9 ng/mL), PFDA (2.4 ng/mL), PFNA (2.1 ng/mL), and others. The pre-conceptional exposure to the selected PFASs was significantly associated, in a chemical-specific pattern, with multiple demographic characteristics and the consumption frequency of different types of food. In particular, the exposure to 6:2 Cl-PFESA was associated with age, parity, alcohol drinking, educational level, household income, and the consumption frequency of red meat, marine and freshwater fish, shellfish, and shrimp. However, our analysis revealed that the investigated sociodemographic and diet variables only explained a relatively small proportion (1.3%-18.7%) of PFAS concentration variations, raising the need of exploring additional factors critical to pre-conceptional PFAS exposure. Overall, the identification of chemical-specific determinants would greatly facilitate the understanding of the link between pre-conceptional exposure and health outcomes, and the mitigation of human exposure to PFAS, particularly the emerging ones.

Global occurrence and probabilistic environmental health hazard assessment of per- and polyfluoroalkyl substances (PFASs) in groundwater and surface waters

Per- and polyfluoroalkyl substances (PFASs) have been used in consumer and military products since the 1950s but are increasingly scrutinized worldwide because of inherent chemical properties, environmental contamination, and risks to public health and the environment. The United States Environmental Protection Agency (USEPA) identified 24 PFASs of interest for further study and possible regulation. We examined 371 peer-reviewed studies published since 2001 to understand the occurrence and distribution of 24 priority PFASs in global surface waters and groundwater. We identified 77,541 and 16,246 data points for surface waters and groundwater, respectively, with total PFAS concentrations ranging from low pg/L to low mg/L levels. Most data were from Asia, Europe, and North America with some reports from Oceania. PFAS information from other geographic regions is lacking. PFASs levels are consistently higher in rivers and streams followed by lakes and reservoirs and then coastal and marine systems. When sufficient data were available, probabilistic environmental hazard assessments (PEHAs) were performed from environmental exposure distributions (EEDs) to identify potential exceedances of available guideline values for each compound by matrix, region, and aquatic system. Specifically, exceedances of USEPA drinking water lifetime health advisory levels were up to 74% for PFOS in groundwater from Oceania and 69% for PFOA in North American groundwater. Our findings support selection of environmentally relevant experimental treatment levels for future toxicology, ecotoxicology and bioaccumulation studies, and potable source water exposure investigations, while highlighting PFASs and major geographic locations requiring additional study and inclusion in global monitoring and surveillance campaigns.

A baseline study of per- and polyfluoroalkyl substances (PFASs) in waterfowl from a remote Australian environment

Elevated concentrations of PFASs in the liver may pose a toxicological risk to bird species and humans that consume them. This study aimed to determine concentrations of 43 per- and polyfluoroalkyl substances (PFASs) in livers (n = 80) of Australian Shelducks (Tadorna tadornoides), Pacific Black Ducks (Anas superciliosa), and Teals (Anas sp.), as well as water and sediment from a remote Australian environment. Maximum concentrations of PFBA (1.9 ng L^-1), PFOA (1.7 ng L^-1) and PFOS (0.99 ng L^-1) in water were consistent with long-range atmospheric and oceanic transport. PFOS (30%) and PFNA (22%) were the most frequently detected PFASs in Australian Shelduck livers (0.31 ± 0.68 ng g^-1 ww and 0.16 ± 0.15 ng g^-1 ww respectively). Maximum concentrations of PFOS in Pacific Black Ducks (50%) and Teals (44%) was 2.4 ng g^-1 ww and 5.3 ng g^-1 ww respectively. While PFAS levels in birds from this remote environment were below current animal consumption guidelines, continued monitoring of this ecosystem is recommended to assess the human health risk of consumption of wild game.

Cross-sectional associations between serum PFASs and inflammatory biomarkers in a population exposed to AFFF-contaminated drinking water

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) are widespread and persistent environmental contaminants. Exposure to several PFASs has been associated with altered immune function in humans, including autoimmune disease and impaired response to vaccination. However, changes to the profile of inflammatory biomarkers in adults exposed to PFASs has not been extensively described.

OBJECTIVE

To estimate cross-sectional associations between serum PFASs and markers of inflammation among adults in a population exposed to aqueous film forming foam (AFFF)-contaminated drinking water.

METHODS

We quantified concentrations of 48 PFASs in non-fasting serum samples from 212 non-smoking adults. In the same serum samples, we measured concentrations of ten pro- and anti-inflammatory cytokines. We restricted analysis to seven PFASs detected in >85% of participants and the following four cytokines detected in ≥30% of participants: interleukin [IL]-1β, IL-6, IL-10, and tumor necrosis factor [TNF]-α. We fit multiple linear regression or logistic regression models, adjusted for potential confounders, to estimate associations between concentrations of each PFAS and either continuous or categorical (above vs below limit of detection) concentrations of each cytokine. We additionally applied Bayesian kernel machine regression to describe the combined effect of the PFAS mixture on each cytokine outcome.

RESULTS

Certain PFAS concentrations in this sample were elevated compared to a US nationally representative sample; median levels of PFHxS, ΣPFOS and ΣPFOA in this sample were 13.8, 2.1 and 1.7 times higher, respectively, than medians observed in the U.S.

SAMPLE

Higher concentrations of multiple PFASs were significantly associated with lower odds of detectable IL-1β. Weaker associations were observed with other cytokines. In general, perfluoroalkyl carboxylic acids had inverse associations with TNF-α, whereas the perfluoroalkyl sulfonic acids showed positive associations.

CONCLUSIONS

We observed preliminary evidence of altered inflammatory profiles among adults with elevated serum concentrations of PFASs due to contaminated drinking water. Modifications to inflammatory pathways may be one mechanism by which PFAS exposures produce adverse health effects in humans, but this finding requires verification in longitudinal studies as well as phenotypic anchoring to immune function outcomes.

Exposure routes, bioaccumulation and toxic effects of per- and polyfluoroalkyl substances (PFASs) on plants: A critical review

Per- and polyfluoroalkyl substances (PFASs) are artificial persistent organic pollutants ubiquitous in ecosystem, and their bioaccumulation and adverse outcomes in plants have attracted extensive concerns. Here, we review the toxic effects of PFASs encountered by various plants from physiological, biochemical and molecular perspectives. The exposure routes and bioaccumulation of PFASs in plants from contaminated sites are also summarized. The bioaccumulation of PFASs in plants from contaminated sites varied between ng/g and μg/g levels. The 50% inhibition concentration of PFASs for plant growth is often several orders of magnitude higher than the environmentally relevant concentrations (ERCs). ERCs of PFASs rarely lead to obvious phenotypic/physiological damages in plants, but markedly perturb some biological activities at biochemical and molecular scales. PFAS exposure induces the over-generated reactive oxygen species and further damages plant cell structure and organelle functions. A number of biochemical activities in plant cells are perturbed, such as photosynthesis, gene expression, protein synthesis, carbon and nitrogen metabolisms. To restore the desire states of cells exposed to PFASs, plants initiate several detoxifying mechanisms, including enzymatic antioxidants, non-enzymatic antioxidants, metallothionein genes and metabolic reprogramming. Future challenges and opportunities in PFAS phytotoxicity studies are also proposed in the review.

Developing potency factors for thyroid hormone disruption by PFASs using TTR-TRβ CALUX® bioassay and assessment of PFASs mixtures in technical products

BACKGROUND

Over the last decade, per- and polyfluoroalkyl substances (PFASs) have become one of the most heavily investigated persistent organohalogen compound class of environmental concern. However, knowledge about their toxicology is still scarce, although PFASs as individual compounds and their industrial mixtures were shown to exert effects on the thyroid hormone system.

METHODS

In vitro toxicity potency factors were established for thyroid hormone transport disruption potential using the novel TTR-TRβ CALUX® bioassay for major PFASs. We assessed technical PFASs mixtures, including aqueous film-forming foam (AFFF) surfactants and chromium mist suppressants (CMS) applications with and without total oxidizable precursor (TOP) by TTR-TRβ CALUX® assay for their thyroid hormone transport disrupting potential.

RESULTS

All PFASs listed in the German guideline for drinking water (German Environment Agency, 2017) affected the T4 binding to TTR, an important plasma thyroid hormone transport protein. For all tested PFASs, potency factors based on PC₈₀ values relative to PFOA could be obtained and ranged between PFBA (0.0018) and PFOS (2.0). Applying in vitro potency factors obtained from the present in vitro TTR-TRβ CALUX® assay study and recently reported in vivo potency factors (Zeilmaker et al., 2018; Bil et al., 2021) on the above-mentioned German guideline for PFAS in drinking water, showed that the cumulative effect-based trigger values (in vivo and in vitro) are comparable (3.0 vs. 2.9 to 4.6 μg PFOA-EQ/l). Additionally, AFFF surfactants and CMS with and without TOP assay were tested. Highest activities were found in the older AFFF surfactants (2013/2014) due to higher PFOS/PFOA levels, which were already substituted with 6:2 FTS in 2019, resulting in much lower PFOA-EQ levels. As expected also the PFOA-EQ levels increased in the samples with TOP treatment compared to the original AFFF surfactants and CMS as confirmed here by biological and chemical PFOA-equivalents (PFOA-EQ) analysis. Additionally, CMS (which have been used in the electroplating chromium industry since the 1950s) as well as PFOS-free, but not PFAS-free fume suppressants (such as Fumetrol® 21) have been tested in the TTR-TRβ CALUX® assay and showed much lower activity levels then the AFFFs, confirmed by the similar potency determination based on chemical PFASs analysis followed by transformation to PFOA-EQ for comparison. The potency factor of 6:2 FTS, which is the main substitute for PFOS in CMS, indicates that it is approximately 100-times less potent as a thyroid hormone disruptor as compared to PFOS.

CONCLUSION

Potency factors based on PC₈₀ values from TTR-TRβ CALUX® relative to PFOA have been developed for major PFASs. In AFFF surfactants and CMS a trend of higher activities with higher amounts of PFOS and PFOA have been found. PFOA and PFOS showed high responses in the TTR-TRβ CALUX® assay and had the largest contributions to the PFOA-EQs in the AFFF surfactants and CMS applications. Using potency factors as determined in the TTR-TRβ CALUX® to convert PFASs assessed by chemical analysis to PFOA-EQ led to comparable results as compared to the results from PFASs measured directly by the TTR-TRβ CALUX® assay. This study supports the claim that semiquantitative effect- and group-based in vitro CALUX bioanalysis tools can be applied effectively to assess industrial products containing complex mixtures with PFAS compounds for which no instrumental analysis are established, and for many compounds where in vitro toxicity data are not yet available.

Legacy and alternative per- and polyfluoroalkyl substances (PFASs) in the West River and North River, south China: Occurrence, fate, spatio-temporal variations and potential sources

Poly- and perfluoroalkyl substances (PFASs) are contaminants of global concern. Studies in Pearl River, south China have focused on the delta area, while the upstream contributions are unclear. Here, we systematically investigated the fate, trends and potential sources of 57 PFASs in river water, sediment and fish of the North and West Rivers of the Pearl River system. Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS) and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2Cl-PFESA) were frequently found compounds in waters, sediments and fish, suggesting their wide usage in this area and potential for bioaccumulation. Waters showed a higher ∑PFASs in the wet season compared to the dry season, but sediments did not. The North River contributed higher PFAS loads to the Pearl River Delta. Our results also reflect the current shift in PFAS usage from legacy substances to alternatives. This study, for the first time, reports data on PFASs in two upstream rivers of the Pearl River and on alternative PFASs such as PFESA in this area, which can better the understanding of their use, fate, risk assessment and further controls and management.

The occurrence of per- and polyfluoroalkyl substances (PFASs) in fluoropolymer raw materials and products made in China

Perfluorooctanoic acid (PFOA), its salts, and related compounds were listed as new persistent organic pollutants by the Stockholm Convention in 2019. In this study, the occurrence of residues of PFOA and other per- and polyfluoroalkyl substances (PFASs) in raw materials and fluoropolymer products from the Chinese fluoropolymer industries are reported for the first time. The PFOA concentrations in raw materials and fluoropolymer products were in the range of 6.7 to 1.1 × 10⁶ ng/g, and <MDL (method detection limit) to 5.3 × 10³ ng/g, respectively. Generally, the levels of PFOA in raw materials were higher than in products, implying that PFOA in the emulsion/dispersion resin could be partly removed during the polymerization or post-processing steps. By tracking a company's polytetrafluoroethylene (PTFE) production line, it was found that over a 5 year period, the residual levels of PFOA in emulsion samples declined from 1.1 × 10⁶ to 28.4 ng/g, indicating that the contamination of PFOA in fluoropolymer products from production source gradually decreased after its use had been discontinued. High concentrations of HFPO-TrA (2.7 × 10⁵ to 8.2 × 10⁵ ng/g) were detected in some emulsion samples indicating this alternative has been widely applied in fluoropolymer manufacturing in China.

Optimized suspect screening approach for a comprehensive assessment of the impact of best management practices in reducing micropollutants transport in the Potomac River watershed

The vast number of chemicals potentially reaching aquatic environment pose a challenge in maintaining the quality of water resources. However, best management practices to improve water quality are typically focused on reducing nutrient transport without assessing how these practices may impact the occurrence of micropollutants. The potential for co-management of nutrients and organic micropollutants exists, but few studies have comprehensively evaluated the suite of contaminants associated with different water quality management practices (riparian zone restoration, stormwater management, etc.). Furthermore, most studies dealing with the determination of micropollutants in environmental samples include only a limited number of target analytes, leaving many contaminants undetected. To address this limitation, there has been a gradual shift in environmental monitoring from using target analysis to either suspect screening analysis (SSA) or non-targeted analysis (NTA), which relies on accurate mass measurements, mass spectral fragmentation patterns, and retention time information obtained using liquid chromatography coupled to high-resolution mass spectrometry. The work presented in this paper focuses on a wide-scope detection of micropollutants in surface water samples from the Potomac River watershed (United States). An in-house database composed of 1039 compounds based on experimental analysis of primary standards was established, and SSA workflow was optimized and applied to determine the presence of micropollutants in surface water. A total of 103 micropollutants were detected in the samples, some of which are contaminants that were not previously monitored and belong to various classes such as pharmaceuticals, personal care products, per-and polyfluoroalkyl substances and other persistent industrial chemicals. The impact of best management practices being implemented for nitrogen and phosphorus reductions were also assessed for their potential to reduce micropollutant transport. This work illustrates the advantages of suspect screening methods to determine a large number of micropollutants in environmental samples and reveals the potential to co-manage a diverse array of micropollutants based on shared transport and transformation mechanisms in watersheds.

Data-independent acquisition with ion mobility mass spectrometry for suspect screening of per- and polyfluoroalkyl substances in environmental water samples

Per- and polyfluoroalkyl substances (PFASs) have environmentally persistent, and the various types of PFASs have been detected in water environments. Many previous studies have performed data-dependent acquisition (DDA) of mass spectra from an environmental sample by high-resolution mass spectrometry to identify PFAS suspects individually. In comparison, the data-independent acquisition (DIA) of comprehensive mass spectra of the sample is a technology which enables to know the occurrences of suspects and non-targets simultaneously. However, it is difficult to associate the fragment ions of targeted precursor ions by retention time only, because of the existence of co-eluting ions derived from environmental samples. Since the separation of ions is not enough with only the conventional DIA method, here, we attempted to support it using ion mobility mass spectrometry (IMS) to distinguish the relevant ions from co-eluting ions by drift time. Firstly, suspect screening of PFASs with eternal database resulted in determining 32-96 PFAS suspects in firefighting foam impacted groundwater samples (n = 8) by suspect screening. Among all the pairs of respective precursor ions and fragment ions of the PFAS suspects, 5%-19% (4-9 PFASs) of them were associated without considering the drift time of IMS, while 37%-49% (15-43 PFASs) of them were associated with considering the drift time. The consideration of the drift time increased the association ratios in all samples. In a sample, most precursor ions could be associated with their fragment ions (41 of 43 PFASs) because at least one probable fragment ion was observed among three of maximum intensity fragment ions. Thus, the method improved the identification by excluding the unrelated co-eluting ions by IMS. Moreover, the method can acquire a certain reliable MS/MS spectra of suspects in environmental samples in one analysis. It is not essential to conduct instrumental analyses again for samples stored for a long time even when the data sets and/or methodologies of data analyses are modified (e.g., the original database, screening list, or statistical filtering/data cleaning approach). It will be particularly useful for studies that must analyze a large number of environmental samples.

Cooking methods affect the intake of per- and polyfluoroalkyl substances (PFASs) from grass carp

Consumption of fish is one of the predominant sources of human exposure to per- and polyfluoroalkyl substances (PFASs). In this study, the effect of various cooking methods (boiling, steaming, grilling and frying) on the levels of PFASs in fish muscle and the intake of PFASs was explored by using grass carp collected from Tangxun Lake, Wuhan, China. Perfluorooctane sulfonate (PFOS) was the predominant PFASs in raw fish fillets, with the concentrations ranging from 59.6 to 136 ng/g ww, followed by perfluorobutane sulfonate (PFBS) (7.73-51.9 ng/g ww). The concentrations of long-chain PFASs in fish increased after cooking, while those of short-chain PFASs decreased. The amounts of PFASs in the cooked fish fillets decreased except PFOS. Short-chain PFASs, including PFBS and perfluoroheptanoic acid (PFHpA), were dominant in cooking juice. The highest amounts of PFBS in the juices were observed after boiling and frying, even higher than those in cooked fish fillets, suggesting that the release of short-chain PFASs to the cooking juices could not be neglected. Based on these results, the intake of short-chain PFASs amount through cooked fish fillets slightly decreased, but the intake of PFOS amount increased. However, consumption of cooking juice (fish soup) could increase the exposure risk of PFBS. Comprehensively considering the increase of PFOS and decrease of total PFASs, boiling may be the relatively better method to cook fish. As PFASs are ubiquitous and inevitable in aquatic food, it is thus important to choose appropriate cooking processes and dietary habits for reducing the intake of different PFASs from fish.

A profile analysis with suspect screening of per- and polyfluoroalkyl substances (PFASs) in firefighting foam impacted waters in Okinawa, Japan

Per- and polyfluoroalkyl substances (PFASs) are a group of persistent contaminants detected in firefighting foam impacted waters. Previous studies have performed suspect and non-target screening by high-resolution mass spectrometry (HRMS) to determine the composition of PFAS contamination and to discover unknown PFASs. Here, we performed a profile analysis with suspect screening against two lists in the NORMAN Suspect List Exchange in firefighting foam impacted environmental and drinking water (n = 18) collected in Okinawa, Japan, in April 2019. Samples were analyzed by liquid chromatography (LC) quadrupole time-of-flight (QTOF) MS in electron spray ionization mode. Suspect screening returned 116 candidate PFASs with their molecular weights, functional groups, and perfluoroalkyl chain lengths. Long-chain perfluoroalkyl acids (PFAAs) and some of their precursors were specifically found around the firefighting training area. Short-chain PFAAs were assumed to be formed from precursors by environmental processes. Perfluoroalkyl sulfonamide precursors were found to be transformed to perfluoroalkyl sulfonic acids (PFSAs) in the drinking water treatment process. In contrast, biological activated carbon filtration formed perfluoroalkyl carboxylic acids (PFCAs). The PFAS profile showed that a large number of different substances needs to be considered.

8:8 Perfluoroalkyl phosphinic acid affects neurobehavioral development, thyroid disruption, and DNA methylation in developing zebrafish

Recent studies have reported potential neurotoxicity and epigenetic alteration associated with exposure to several per- and polyfluoroalkyl substances (PFASs). However, such information is limited to a few compounds (e.g., perfluorooctane sulfonate), primarily based on rodent experiments, and the underlying toxicological mechanism(s) for many PFAS in the environment remain poorly understood. In the present study, we investigated 8:8 perfluoroalkyl phosphinic acid (8:8 PFPiA), an under-studied PFAS with high persistency in the environment and biota, using the zebrafish model. We exposed zebrafish embryos (<4 hpf) to various concentrations of 8:8 PFPiA (0, 0.0116, 0.112, 0.343, 1.34, 5.79 μM) for 144 h. Although there was no significant change in survival, hatchability and malformations, zebrafish locomotor speed at 120 h significantly decreased in dark photoperiod. At 144 h, several genes related to thyroid hormones that are essential for neurodevelopment, including corticotropin releasing hormone b (crhb), iodothyronine deiodinase 3a (dio3a), thyroid-stimulating hormone receptor (tshr) and nkx2 homeobox1 (nkx 2.1), were up-regulated by 8:8 PFPiA at 5.79 μM. 8:8 PFPiA also significantly down-regulated a neurodevelopmental gene, elav like neuron-specific RNA binding protein (elavl3), at 1.34 and 5.79 μM; in addition, one oxidative stress gene was slightly but significantly up-regulated. Further, global DNA methylation was significantly decreased at higher treatment levels, identifying effects of 8:8 PFPiA on epigenetic regulation. However, promoter DNA methylation of selected genes (dio3, tshr, nkx2.1) were not statistically altered, though dio3 methylation showed a decreasing trend with 8:8 PFPiA exposure. Our results specifically advance an understanding of molecular toxicology of PFPiA and more broadly present an approach to define diverse responses during animal alternative assessments of PFASs.

A sensitive method for simultaneous determination of 12 classes of per- and polyfluoroalkyl substances (PFASs) in groundwater by ultrahigh performance liquid chromatography coupled with quadrupole orbitrap high resolution mass spectrometry

Per- and polyfluoroalkyl substances (PFASs) comprise a large group of chemicals with diverse physicochemical properties, which make their simultaneous determination a challenging task. A trace analytical method based on ultrahigh performance liquid chromatography-quadrupole Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was developed for simultaneous determination of 54 PFASs belonging to 12 classes in groundwater, including 24 perfluorocarbons and 30 precursors. This method provided good linearity of calibration standards (R² > 0.99), excellent method limits of quantification (MLOQs) (0.5-250 pg/L), satisfactory matrix spiking recoveries (63%-148%), high precision (intra-day relative standard deviations (RSDs) 1.4-11.4%, inter-day RSDs 1.6-12.9%, and inter-week RSDs 2.1-12.7%), and short runtime (13 min), suitable for high throughput studies. The newly established method was successfully applied to detect PFASs in the groundwater samples collected from Hebei Province, China. Twenty PFASs were detected with the total concentration of 0.3-32.9 ng/L, indicating the contamination level similar to that in drinking water. The dominant PFASs were perfluorobutanesulfonate (PFBS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA) and perfluorooctanoic acid (PFOA). In addition, 6:2 fluorotelomer phosphate diester (6:2 diPAP) and 6:2 fluorotelomer sulfonate (6:2 FTS) were found as the major precursors. The total PFAS concentrations were lower than the cumulative permissible limit of 70 ng/L for PFOS and PFOA recommended by the United States Environmental Protection Agency (USEPA) for drinking water in 2016. In a nutshell, this study provided a fast and sensitive method based on HRMS for the simultaneous analysis of a wide range of PFASs, present at trace levels in groundwater samples.

Per- and polyfluoroalkyl substances and the contribution of unknown precursors and short-chain (C2-C3) perfluoroalkyl carboxylic acids at solid waste disposal facilities

The emission of per- and polyfluoroalkyl substances (PFASs) from municipal solid wastes (MSW) disposal raises concerns for their potential of long-term release and risks. In this study, the occurrence of PFASs was investigated in ambient air and leachate from seven MSW disposal facilities including three landfills, two incineration plants, and two MSW transfer stations in Tianjin, China. Mass loads of PFASs (≥C4) released to the atmosphere were estimated at 0.007-0.97 kg/y/site, which were much lower than those to leachate (0.04-1.3 kg/y/site), while emission to the atmosphere at landfills was more considerable. With total oxidizable precursor (TOP) assay, unknown C4-C12 perfluoroalkyl acids (PFAAs)-precursors were found contributing 10-97 mol% in leachate and accounting for additional 15%-43% mass loads. Using IC-Ba/Ag/H cartridges, trifluoroacetic acid (C2) and perfluoropropionic acid (C3) were recovered in leachate for TOP assay (62%-78%) and determined at dominant levels of 19-81 μg/L, which accounted for mass loads of 0.08-2.6 kg/y/site. Unknown C2-C3 PFAA-precursors contributed 12-93 mol% with mass loads of 0.10-3.0 kg/y/site. Overall, unknown C2-C12 PFAA-precursors remained contributing 0.35-68 mol% in biochemically treated leachate. This study emphasizes that the profiles of unknown PFAA-precursors released during MSW disposal are to be identified, which is essential for their environmental risk assessment.

Subacute dermal toxicity of perfluoroalkyl carboxylic acids: comparison with different carbon-chain lengths in human skin equivalents and systemic effects of perfluoroheptanoic acid in Sprague Dawley rats

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are used in various fields but raise concerns regarding human health and environmental consequences. Among PFASs, perfluorooctanoic acid (PFOA) and short-chain perfluoroalkyl carboxylic acids (SC PFCAs) are detectable in skin-contact consumer products and have dermal absorption potential. Here, we investigated the effects of dermal exposure to PFOA and SC PFCAs using in vitro and in vivo models. Human skin equivalents were topically treated with 0.25 mM and 2.5 mM PFOA and SC PFCAs (perfluoropentanoic acid, PFPeA; perfluorohexanoic acid, PFHxA; and perfluoroheptanoic acid, PFHpA) for 6 days, and cell viability, interleukin (IL)-1α, oxidative stress markers (malondialdehyde, MDA; and 8-hydroxydeoxyguanosine, 8-OHdG), and histopathology were examined. MDA levels were significantly higher in the PFASs groups than in controls. Compared with SC PFCAs, 2.5 mM PFOA caused more IL-1α (p < 0.001) release, decreased skin thickness and microscopic abnormalities. To evaluate systemic effects, Sprague Dawley (SD) rats were dermally treated with 250 and 1000 mg/kg PFHpA for 2 weeks and clinical and anatomic pathology were assessed. At 1000 mg/kg, 83% of the rats died, with severe ulcerative dermatitis at the application site. Adverse PFHpA-treated systemic changes were observed in the kidney, liver and testes, and histopathologic lesions such as renal tubular necrosis, hepatocellular necrosis, and germ cell degeneration were seen at 250 and 1000 mg/kg. Our study suggests that SC PFCAs have fewer effects on the skin than PFOA, but SC PFCAs can have adverse effects on major organs with systemic exposure at high concentrations.

A new method to search for per- and polyfluoroalkyl substances (PFASs) by linking fragmentation flags with their molecular ions by drift time using ion mobility spectrometry

Per- and polyfluoroalkyl substances (PFASs) are a group of anthropogenic organic fluorinated compounds that have been detected widely. To discover unknown PFASs, previous researchers have applied high-resolution mass spectrometer using fragmentation flagging approach with common fragment ion at the same retention time as the flags. However, it was difficult to search for their molecular ion from co-eluting peaks in the full-scan spectrum at a specific retention time. Here, we attempted to utilize drift time acquired by ion mobility spectrometry for making linkages between fragment ions and their molecular ions. For validating the process, standard solution spiked with PFASs were analyzed by liquid chromatography/ion mobility - quadrupole time-of-flight mass spectrometry (LC/IM-QTOF-MS). Fluorinated fragment ions (fragmentation flags) were categorized into three classes: Class 1 (120 types of [C_xF_y]^-), Class 2 (123 types of [C_xF_yO]^-), Class 3 (131 types of [C_xF_yO₃S]^-) and all overlapping fragmentation flags detected at an identical retention time were bundled together as a "flag set". Injecting standard mixed solution of 20 types of PFASs resulted in picking up 20 flag sets by fragmentation flagging. All the fragmentation flags were detected within a designated range of drift time, and their molecular ion was confirmed as a PFAS spiked in the standard solution even when co-eluting compounds were found at almost same retention time. This method was applied to a household fire extinguisher liquid, resulting in finding out nine molecular ions. Therefore, the new linking method achieved rapid searching for the prospective molecular ions using LC/IM-QTOF-MS.

Per- and polyfluoroalkyl substances display structure-dependent inhibition towards UDP-glucuronosyltransferases

Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals and can be detected in environmental and human samples all over the world. Toxicity of existing and emerging PFASs will be a long-term source of concern. This study aimed to investigate structure-dependent inhibitory effects of 14 PFASs towards the activity of 11 UDP-glucuronosyltransferase (UGT) isoforms. In vitro UGTs-catalyzed glucuronidation of 4-methylumbelliferone (4-MU) was employed to determine the inhibition of PFASs towards different UGT isoforms. All the PFASs showed <75% of inhibition or stimulation effects on UGT1A3, UGT1A7, UGT1A9, UGT2B4, UGT2B7 and UGT2B17. However, PFASs showed broad inhibition on the activity of UGT1A1 and UGT1A8. The activity of UGT1A1 was inhibited by 98.8%, 98%, 79.9%, 77.1%, and 76.9% at 100 μmoL/L of perfluorodecanoic acid (PFDA), perfluorooctanesulfonic acid potassium salt (PFOS), perfluorotetradecanoic acid (PFTA), perfluorooctanoic acid (PFOA) and perfluorododecanoic acid (PFDoA), respectively. UGT1A8 was inhibited by 97.6%, 94.8%, 86.3%, 83.4% and 77.1% by PFDA, PFTA, perfluorooctadecanoic acid (PFOcDA), PFDoA and PFOS, respectively. Additionally, PFDA significantly inhibited UGT1A6 and UGT1A10 by 96.8% and 91.6%, respectively. PFDoA inhibited the activity of UGT2B15 by 88.2%. PFDA and PFOS exhibited competitive inhibition towards UGT1A1, and PFDA and PFTA showed competitive inhibition towards UGT1A8. The inhibition kinetic parameter (K_i) were 3.15, 1.73, 13.15 and 20.21 μmoL/L for PFDA-1A1, PFOS-1A1, PFDA-1A8 and PFTA-1A8, respectively. The values were calculated to be 0.3 μmoL/L and 1.3 μmoL/L for the in vivo inhibition of PFDA towards UGT1A1-and UGT1A8-catalyzed metabolism of substances, and 0.2 μmoL/L and 2.0 μmoL/L for the inhibition of PFOS towards UGT1A1 and the inhibition of PFTA towards UGT1A8, respectively. Molecular docking indicated that hydrogen bonds and hydrophobic interactions contributed to the interaction between PFASs and UGT isoforms. In conclusion, exposure to PFASs might inhibit the activity of UGTs to disturb metabolism of endogenous compounds and xenobiotics. The structure-related effects of PFASs on UGTs would be very important for risk assessment of PFASs.

Preliminary assessment of exposure to persistent organic pollutants among pregnant women in Puerto Rico

BACKGROUND

Puerto Rico has over 200 hazardous waste sites, as well as higher rates of several adverse health outcomes compared to the mainland US. In response to concerns of potential links between environmental contaminant exposure and preterm birth, the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) birth cohort was formed. Biomarkers of exposure for several contaminants have been found to be elevated in this cohort compared to women of child-bearing age in the National Health and Nutrition Examination Survey (NHANES). However, exposure to persistent organic pollutants (POPs) has not been evaluated.

METHODS

In this preliminary analysis, we measured four classes of POPs, including perfluoroalkyl substances (PFASs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and several persistent pesticides in serum samples collected at 16-20 weeks gestation from the first 48 women enrolled in PROTECT. We performed descriptive analyses for each analyte, assessed correlations between analytes using Spearman correlations, and compared serum levels in PROTECT women to levels in NHANES women aged 18-40.

RESULTS

Several PFASs were detected in 96-100% of samples, with moderate to strong correlations between most PFASs (range r = 0.44-0.88). BDE47, BDE153, PCB 138-158, PCB153 and p,p'-dichlorodiphenyldichloroethene (p,p'-DDE) were detected in the majority of samples, with strong correlations between PCBs and p,p'-DDE (range r = 0.59-0.74). The median concentration for each analyte was lower than, sometimes by a factor of 4 (e.g. BDE47, p,p'-DDE), the median concentration reported in NHANES women aged 18-40.

CONCLUSION

Although participants in the ongoing PROTECT birth cohort have higher exposure to many environmental contaminants, this preliminary study suggests that they have lower exposure to several POPS, specifically PCBs, OCPs, PFASs, and PBDEs.

Degradation and defluorination of 6:2 fluorotelomer sulfonamidoalkyl betaine and 6:2 fluorotelomer sulfonate by Gordonia sp. strain NB4-1Y under sulfur-limiting conditions

6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB) is a major component of aqueous film-forming foams (AFFFs) used for firefighting and is frequently detected, along with one of its suspected transformation products, 6:2 fluorotelomer sulfonate (6:2 FTSA), in terrestrial and aquatic ecosystems impacted by AFFF usage. Biochemical processes underlying bacterial biodegradation of these compounds remain poorly understood due to a lack of pure culture studies. Here, we characterized the water-soluble and volatile breakdown products of 6:2 FTSA and 6:2 FTAB produced using Gordonia sp. strain NB4-1Y cultures over seven days under sulfur-limited conditions. After 168 h, 99.9% of 60 μM 6:2 FTSA was degraded into ten major breakdown products, with a mol% recovery of 88.2, while 70.4% of 60 μM 6:2 FTAB was degraded into ten major breakdown products, with a mol% recovery of 84.7. NB4-1Y uses two pathways for 6:2 FTSA metabolism, with 55 mol% of breakdown products assigned to a major pathway and <1.0 mol% assigned to a minor pathway. This work indicates that rapid transformation of 6:2 FTSA and 6:2 FTAB can be achieved under controlled conditions and improves the bacterial metabolism of these compounds.

Sulfluramid use in Brazilian agriculture: A source of per- and polyfluoroalkyl substances (PFASs) to the environment

N-Ethyl perfluorooctane sulfonamide (EtFOSA) is a perfluorooctane sulfonate (PFOS) precursor and the active ingredient in sulfluramid, a pesticide which is used extensively in Brazil for management of leaf cutting ants. Here we investigate the occurrence of EtFOSA, PFOS, and other per- and polyfluoroalkyl substances (PFASs) in soil, eucalyptus leaves, water (ground, riverine, and coastal (estuarine/marine)) and coastal sediment from an agricultural region of Bahia State, Brazil. This area contains a larger number of eucalyptus plantations where sulfluramid is suspected to be applied. Soil, leaves, and coastal water (marine/estuarine) contained ∑PFAS concentrations of up to 5400 pg g^-1, 979 pg g^-1, and 1020 pg L^-1, respectively, with PFAS profiles generally dominated by PFOS and perfluorooctane sulfonamide (FOSA). Coastal sediment contained ∑PFAS concentrations of up to 198 pg g^-1, with PFOS, FOSA, and perfluorooctanoic acid (PFOA) being the most frequently observed PFASs. These substances are all potential EtFOSA transformation products, pointing to sulfluramid as a possible source. In riverine water, ∑PFAS concentrations of up to 8930 pg L^-1 were observed. PFOS and PFOA were detected in all river water samples. Groundwater also exhibited PFAS contamination (5730 pg L^-1 ∑PFASs), likely from sulfluramid use. The observation of other PFASs (e.g. perfluorobutanoic acid) in freshwater suggests that other PFAS sources (in addition to sulfluramid) may be important in this region. Overall, these data support the hypothesis that sulfluramid use contributes to the occurrence of PFASs in the Brazilian environment.

Circulating levels of perfluoroalkyl substances and left ventricular geometry of the heart in the elderly

AIMS

Some persistent organic pollutants (POPs) such as hexachlorobenzene (HCB) and some polychlorinated biphenyls (PCBs) have been shown to interfere with myocardial function and geometry. We therefore investigated if also another group of POPs: per- and polyfluoroalkyl substances (PFASs) were associated with alterations in left ventricular geometry.

METHODS

801 subjects aged 70 years were investigated in a cross-sectional study within the scope of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Eight PFASs were detected in >75% of participants´ plasma by ultra-performance liquid chromatograph/tandem mass spectrometry. Left ventricular geometry was determined by echocardiography. Multivariable linear regression was used to investigate the associations between PFASs and left ventricular geometry of the heart after exclusion of subjects with previous myocardial infarction (n = 72).

RESULTS

When adjusting for multiple comparisons, none of the eight PFASs evaluated were significantly related to left ventricular mass. However, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) were related to relative wall thickness (RWT) in a negative fashion (p < 0.0021). Besides being inversely related to RWT, PFNA was also positively related to left ventricular end-diastolic volume (LVEDD) (p < 0.0021). These analyses were adjusted for traditional cardiovascular risk factors.

CONCLUSION

In this cross-sectional study, several of the PFASs evaluated, especially PFNA, were related to myocardial geometry: a reduction in relative wall thickness and an increase in left ventricular diameter following adjustment for traditional cardiovascular risk factors, suggesting a role for PFASs in cardiac remodeling.

Multianalyte profiling of per- and polyfluoroalkyl substances (PFASs) in liquid commercial products

The chemical properties of poly- and perfluoroalkyl substances (PFASs) make them widespread for use in a number of industrial and commercial products to confer water and oil-repellency characteristics and to reduce surface tension e.g. in aqueous film-forming foams (AFFFs). Some PFASs, especially perfluoroctane sulfonate, and several perfluoroalkyl carboxylic acids, are known to cause significant human and environmental negative impact. Our knowledge on the content of PFASs in products remains scarce due to limited information available, thus impeding any precise assessment of human exposure and environmental release upon use. This study aimed at analyzing a wide variety of liquid products (n = 194) likely to contain PFASs, including impregnating agents, lubricants, cleansers, polishes, AFFFs and other industrial products. By means of LC- and GC-MS/MS analytical techniques, 24 PFASs (from 41 targeted PFASs) were detected and quantified in 55% of samples. PFAS quantification and profiling was found to be consumer product specific. PFASs were mostly detected in AFFF (90%) and impregnating agents (60%) with mainly ionic and neutral species, respectively. In particular, the fluorotelomer alcohols 6:2, 8:2 and 10:2 FTOHs were detected in 40-50% of impregnating agents. Further investigation by Fast Atom Bombardment Mass Spectrometry (FAB-MS) on a set of AFFF samples allowed the characterization of 8 different PFAS classes as major components in these formulations. Results demonstrated that numerous and diversified PFAS are currently used in specific commercial products, implying significant human exposure and environmental release that necessitate further research concerning their toxicological impact.

The impact of two fluoropolymer manufacturing facilities on downstream contamination of a river and drinking water resources with per- and polyfluoroalkyl substances

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that have been detected in the environment, biota, and humans. Drinking water is a route of exposure for populations consuming water contaminated by PFAS discharges. This research study reports environmental measurement concentrations, mass flows, and the fate of dozens of PFASs in a river receiving effluents from two fluoropolymer manufacturing facilities. In addition to quantified levels of PFASs using LC- and GC-MS analytical methods, the total amount of unidentified PFASs and precursors was assessed using two complementary analytical methods, absorbable organic fluorine (AOF) determination and oxidative conversion of perfluoroalkyl carboxylic acid (PFCA) precursors. Several dozen samples were collected in the river (water and sediment) during four sampling campaigns. In addition, samples were collected in two well fields and from the outlet of the drinking water treatment plants after chlorination. We estimated that 4295 kg PFHxA, 1487 kg 6:2FTSA, 965 kg PFNA, 307 kg PFUnDA, and 14 kg PFOA were discharged in the river by the two facilities in 2013. High concentrations (up to 176 ng/g dw) of odd long-chain PFASs (PFUnDA and PFTrDA) were found in sediment samples. PFASs were detected in all 15 wells, with concentrations varying based on the location of the well in the field. Additionally, the presence of previously discharged PFASs was still measurable. Significant discrepancies between PFAS concentration profiles in the wells and in the river suggest an accumulation and transformation of PFCA precursors in the aquifer. Chlorination had no removal efficiency and no unidentified PFASs were detected in the treated water with either complementary analytical method. Although the total PFAS concentrations were high in the treated water, ranging from 86 to 169 ng/L, they did not exceed the currently available guideline values.

Evaluation of the immunomodulatory effects of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate in C57BL/6 mice

2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate was designed to replace perfluorooctanoic acid (PFOA), which has been mostly phased out of U.S. production due to environmental persistence, detectable human and wildlife serum concentrations, and reports of systemic toxicity. In rodent models, PFOA exposure suppresses T cell-dependent antibody responses (TDAR) and vaccine responses in exposed humans. To determine replacement compound effects on TDAR and related parameters, male and female C57BL/6 mice were gavaged with 0, 1, 10, or 100 mg/kg/day for 28 days. Mice immunized with antigen on day 24 were evaluated for TDAR and splenic lymphocyte subpopulations five days later. Serum and urine were collected for test compound concentrations and liver peroxisome proliferation was measured. Relative liver weight at 10 and 100 mg/kg and peroxisome proliferation at 100 mg/kg were increased in both sexes. TDAR was suppressed in females at 100 mg/kg. T lymphocyte numbers were increased in males at 100 mg/kg; B lymphocyte numbers were unchanged in both sexes. Females had less serum accumulation and higher clearance than males, and males had higher urine concentrations than females at all times and doses. While this PFOA-replacement compound appears less potent at suppressing TDAR relative to PFOA, it produces detectable changes in parameters affected by PFOA; further studies are necessary to determine its full immunomodulatory profile and potential synergism with other per- and polyfluoroalkyl substances of environmental concern.

Spatial distribution and source tracing of per- and polyfluoroalkyl substances (PFASs) in surface water in Northern Europe

The impact of point and diffuse sources for 26 per- and polyfluoroalkyl substances (PFASs) in northern Europe were investigated by studying Swedish rivers (n = 40) and recipient seawater (Baltic Sea and Kattegat; n = 18). Different composition profiles were observed in the rivers, with ten rivers having a remarkably high fraction of perfluoroalkane sulfonic acids (PFSAs; 65% of the ƩPFASs) as compared to other rivers (19%) suggesting major impact of one or several source types dominated by PFSAs. Population density and low latitude (south) were strongly correlated to the widely used perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) as well as to perfluorohexanesulfonic acid (PFHxS). Significant relationships between several PFCAs and PFSAs (i.e. perfluorobutanoic acid (PFBA), perfluoroheptanoic acid (PFHpA), PFOA, perfluorobutanesulfonic acid (PFBS), and PFHxS) and dissolved organic carbon (DOC) were detected (p < 0.05), indicating chemical binding and co-transport with DOC in fresh water and seawater. Partial least squares regression analysis showed that perfluoroalkyl carboxylic acids (PFCAs) were related to latitude according to their perfluorocarbon chain length (C₃, C₇, C₈, C₉, C₁₀ and C₁₁), with longer chains associated with higher latitudes. This suggests the presence of mechanisms promoting higher prevalence of longer chained PFCAs in the north, e.g. precursor degradation, and/or aerosol associated stabilization of PFCAs and their precursors.

Poly- and perfluoroalkylated substances (PFASs) in water, sediment and fish muscle tissue from Lake Tana, Ethiopia and implications for human exposure

Lake Tana is Ethiopia's largest lake and there are plans to increase the harvest of fish from the lake. The objective of this study was to assess the levels of poly- and perfluoroalkyl substances (PFASs) in different compartments of the lake (water, sediment, and fish muscle tissue), and its implications for human exposure. The results showed higher PFAS concentrations in piscivorous fish species (Labeobarbus megastoma and Labeobarbus gorguari) than non-piscivorous species (Labeobarbus intermedius, Oreochromis niloticus and Clarias gariepinus) and also spatial distribution similarities. The ∑PFAS concentrations ranged from 0.073 to 5.6 ng L^-1 (on average, 2.9 ng L^-1) in surface water, 0.22-0.55 ng g^-1 dry weight (dw) (on average, 0.30 ng g^-1 dw) in surface sediment, and non-detected to 5.8 ng g^-1 wet weight (ww) (on average, 1.2 ng g^-1 ww) in all fish species. The relative risk (RR) indicates that the consumption of fish contaminated with perfluorooctane sulfonate (PFOS) will likely not cause any harmful effects for the Ethiopian fish eating population. However, mixture toxicity of the sum of PFASs, individual fish consumption patterns and increasing fish consumption are important factors to consider in future risk assessments.

Human exposure to per- and polyfluoroalkyl substances (PFASs) via house dust in Korea: Implication to exposure pathway

A wide range of per- and polyfluoroalkyl substances (PFASs), including fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamidoethanols (FOSEs), perfluoroalkyl carboxylic acids (PFCAs), and perfluoroalkane sulfonic acids (PFSAs), were measured in fifteen house dust and two nonresidential indoor dust of Korea. Total concentrations of PFASs in house dust ranged from 29.9 to 97.6 ng g(-1), with a dominance of perfluorooctane sulfonic acid (PFOS), followed by 8:2 FTOH, N-Ethyl perfluorooctane sulfonamidoethanol (EtFOSE), perfluoroctanoic acid (PFOA). In a typical exposure scenario, the estimated daily intakes (EDIs) of total PFASs via house dust ingestion were 2.83 ng d(-1) for toddlers and 1.13 ng d(-1) for adults, which were within the range of the mean EDIs reported from several countries. For PFOA and PFOS exposure via house dust ingestion, indirect exposure (via precursors) was a minor contributor, accounting for 5% and 12%, respectively. An aggregated exposure (hereafter, overall-EDIs) of PFOA and PFOS occurring via all pathways, estimated using data compiled from the literature, were 53.6 and 14.8 ng d(-1) for toddlers, and 20.5 and 40.6 ng d(-1) for adults, respectively, in a typical scenario. These overall-EDIs corresponded to 82% (PFOA) and 92% (PFOS) of a pharmacokinetic model-based EDIs estimated from adults' serum data. Direct dietary exposure was a major contributor (>89% of overall-EDI) to PFOS in both toddlers and adults, and PFOA in toddlers. As for PFOA exposure of adults, however direct exposure via tap water drinking (37%) and indirect exposure via inhalation (22%) were as important as direct dietary exposure (41%). House dust-ingested exposure (direct+indirect) was responsible for 5% (PFOS in toddlers) and <1% (PFOS in adults, and PFOA in both toddlers and adults) of the overall-EDIs. In conclusion, house-dust ingestion was a minor contributor in this study, but should not be ignored for toddlers' PFOS exposure due to its significance in the worst-case scenario.

How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances

This review examines the usefulness of the metrics BMF (biomagnification factor) and TMF (trophic magnification factor), derived from field measurements of the levels of contaminants in naturally occurring biota, for characterizing the bioaccumulation potential ("B") of chemicals. Trophic magnification factor and BMF values greater than 1.0 are often considered to be the most conclusive indicators of B status, and the TMF criterion has been referred to as the "gold standard" for B categorization. Although not wishing to dispute the theoretical primacy of field-derived BMFs and TMFs as B metrics, we make the case that, in practice, the study-to-study (and even within-study) variability of the results is so great that they are of very restricted usefulness for assessing B status, at least in the case of the per- and polyfluoroalkyl substances (PFASs), on which we focus here. This conclusion is based on an analysis of the results of 24 peer-reviewed studies reporting field-derived BMFs or TMFs for 14 PFASs, for which BMF values often range over several orders of magnitude from <<1.0 to >>1.0, sometimes even in the same study. For TMFs, the range is a factor of approximately 20 for the most intensely studied PFASs (perfluorooctanoic acid [PFOA] and perfluorooctanesulfonic acid [PFOS]). We analyze the possible causes for such variability: To some extent it results from the differing ways in which the metrics are expressed, but most of the scatter is likely attributable to such factors as nonachievement of the tacitly assumed steady-state conditions, uncertainties in the feeding ecology, the impact of metabolism of precursor compounds, and so forth. As more trustworthy alternatives to field-derived BMFs and TMFs, we suggest the implementation of dietary BMF studies performed under strictly controlled conditions on aquatic, terrestrial, and avian species, as well as the consideration of measured elimination half-lives, which have been demonstrated to be directly related to BMF values.

Characterizing direct emissions of perfluoroalkyl substances from ongoing fluoropolymer production sources: A spatial trend study of Xiaoqing River, China

The spatial trend of perfluoroalkyl substances (PFASs) along Xiaoqing River and its tributaries was studied to characterize isomer profiles and quantify emissions from fluoropolymer (FP) manufacturers in China. Substantially elevated ∑PFAS concentrations downstream of tributary 4 demonstrated that the emissions from this FP manufacturer dominated total riverine discharges. Isomer profiles of perfluorooctanoic acid (PFOA) in water displayed a stepwise increase in percentage branched PFOA downstream of tributary 3 (14.0%) and 4 (22.7%) reflecting the importance of FP sources. Strong positive correlations between PFOA isomers in water downstream of tributary 4 indicated that isomer profiles were conserved from emission sources to the final reservoir. Riverine discharges of PFOA (23-67 t/yr) were in agreement with theoretical emission calculations from FP production (68 t/yr) whereas large discrepancies between the two methodologies were observed for perfluorobutanoic acid and perfluoropentanoic acid. Collectively, this study fills critical knowledge gaps for understanding ongoing global sources of PFASs.

Stockholm Arlanda Airport as a source of per- and polyfluoroalkyl substances to water, sediment and fish

Fire training facilities are potential sources of per- and polyfluoroalkyl substances (PFASs) to the nearby environment due to the usage of PFAS-containing aqueous fire-fighting foams (AFFFs). The multimedia distribution of perfluoroalkyl carboxylates (PFCAs), perfluoroalkyl sulfonates (PFSAs), perfluorooctanesulfonamide (PFOSA) and 6:2 fluorotelomer sulfonate (FTSA) was investigated near a fire training facility at Stockholm Arlanda Airport in Sweden. The whole body burden of PFASs in European perch (Perca fluviatilis) was 334±80μg absolute and was distributed as follows: Gonad>liver≈muscle>blood>gill. The bioconcentration factor (BCF) and sediment/water partition coefficient (Kd) increased by 0.6-1.7 and 0.2-0.5 log units, respectively, for each additional CF2 moiety for PFCAs and PFSAs. PFAS concentrations in water showed no significant decreasing trend between 2009 and 2013 (p>0.05), which indicates that Stockholm Arlanda Airport may be an important source for long-term contamination of the nearby environment with PFASs.

Occurrence and distribution of conventional and new classes of per- and polyfluoroalkyl substances (PFASs) in the South China Sea

Concentrations of 23 per- and polyfluoroalkyl substances (PFASs), including new classes of PFASs, in seawater samples were investigated for their occurrence and the interaction of the ocean currents with the distribution of PFASs in the South China Sea. This study revealed that socio-economic development was associated with the PFAS contamination in coastal regions of South China. Significant correlations between concentration of total PFASs with gross domestic product (GDP) per capita and population density were found in the areas, suggesting that the influence of intense human activities in these areas may have resulted in higher PFAS contamination to the adjacent environment. Di-substituted polyfluoroalkyl phosphate (diPAP), one of the potential replacements for PFASs, was only detected in the heavily developed region, namely Pearl River Delta (PRD). Total PFAS concentrations, ranging from 195 to 4925 pg/L, were detected at 51 sampling stations of the South China Sea. The results also confirmed that PFAS contamination in the South China Sea is strongly affected by the ocean currents. In comparison to perfluoroactane sulfonate (PFOS) concentrations measured nine years ago at the same locations, the concentrations in this study were found to be two times higher. This indicated that the use and production of perfluoroalkyl sulfonates (PFSAs) has been continuing in the region.

Perfluoroalkyl acids and their precursors in Swedish food: The relative importance of direct and indirect dietary exposure

We analyzed food market basket samples obtained in Sweden from 1999, 2005, and 2010 for perfluoroalkyl acids (PFAAs) and a range of precursor compounds. Perfluorooctane sulfonic acid (PFOS) precursors were detected in all food year pools with the highest concentrations in 1999. Six polyfluoroalkyl phosphate diesters (diPAPs, 4:2/6:2, 6:2/6:2, 6:2/8:2, 8:2/8:2, 6:2/10:2, and 10:2/10:2) were detected in the year pools with the highest ∑diPAP concentrations in 1999 and 2005. All precursors were predominantly found in meat, fish, and/or eggs based on analysis of individual food groups from 1999. Based on year pools, PFOS precursors contributed between 4 and 1% as an indirect source to total dietary PFOS intakes between 1999 and 2010. Perfluorohexanoic acid (PFHxA) exposure originated entirely from diPAPs, whereas for perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA), diPAPs contributed between 1 and 19% to total exposure. The lowest precursor contributions were generally seen in food samples from 2010.

The fate of per- and polyfluoroalkyl substances within a melting snowpack of a boreal forest

Per- and polyfluoroalkyl substances (PFAS) were measured systematically in a snowpack in northern Sweden to determine chemical behaviour during seasonal melt. Average PFAS concentrations were generally low, but displayed a wide range with median (range) concentrations of PFOA and PFOS of 66.5 pg L(-1) (ND-122) and 20.5 pg L(-1) (2.60-253) respectively. Average concentrations of the shorter chain, C4 and C5 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), were ∼10-fold higher. Differences in the PFAS concentrations and profile were observed between surface snow and deeper layers, with evidence of PFAS migration to deeper snow layers as melt progressed. Chemical loads (ng m(-2)) for C4-9 PFCAs decreased gradually as melt progressed, but increased for C4, C6-8 PFSAs and the longer chain C10-12 PFCAs. This enrichment in the diminishing snowpack is an unusual phenomenon that will affect PFAS elution with meltwater and subsequent entry to catchment surface waters.