Perfluoroalkyl Substances Compounds Research Articles

An environmentally relevant mixture of Perfluoroalkyl Substances (PFAS) impacts proliferation, steroid hormone synthesis, and gene transcription in primary human granulosa cells.

Perfluoroalkyl substances (PFAS) are a group of synthetic chemicals that are resistant to biodegradation and are environmentally persistent. PFAS are found in many consumer products and are a major source of water and soil contamination. This study investigated the effects of an environmentally relevant PFAS mixture [perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS)] on the transcriptome and function of human granulosa cells (hGCs). Primary hGCs were harvested from follicular aspirates of healthy, reproductive-age women who were undergoing oocyte retrieval for in vitro fertilization. LC/MS-MS was performed to identify PFAS compounds in pure follicular fluid. Cells were cultured with vehicle control or a PFAS mixture (2 nM PFHxS, 7 nM PFOA, 10 nM PFOS) for 96h. Analyses of cell proliferation/apoptosis, steroidogenesis, and gene expression were measured via MTT assays/immunofluorescence, ELISA/western blotting, and RNA sequencing/bioinformatics, respectively. PFOA, PFOS, and PFHxS were detected in 100% of follicle fluid samples. Increased cell proliferation was observed in hGCs treated with the PFAS mixture with no impacts on cellular apoptosis. The PFAS mixture also altered steroid hormone synthesis, increasing both FSH-stimulated and basal progesterone secretion and concomitant upregulation of STAR protein. RNA sequencing revealed inherent differences in transcriptomic profiles in hGCs after PFAS exposure. This study demonstrates functional and transcriptomic changes in hGCs after exposure to a PFAS mixture, improving our knowledge about the impacts of PFAS exposures and female reproductive health. These findings suggest that PFAS compounds can disrupt normal granulosa cell function with possible long-term consequences on overall reproductive health.

Investigating the applicability domain of the hiPSC-based PluriLum assay: an embryotoxicity assessment of chemicals and drugs

To meet the growing demand for developmental toxicity assessment of chemicals, New Approach Methodologies (NAMs) are needed. Previously, we developed two 3D in vitro assays based on human-induced pluripotent stem cells (hiPSC) and cardiomyocyte differentiation: the PluriBeat assay, based on assessment of beating differentiated embryoid bodies, and the PluriLum assay, a reporter gene assay based on the expression of the early cardiac marker NKX2.5; both promising assays for predicting embryotoxic effects of chemicals and drugs. In this work, we aimed to further describe the predictive power of the PluriLum assay and compare its sensitivity with PluriBeat and similar human stem cell-based assays developed by others. For this purpose, we assessed the toxicity of a panel of ten chemicals from different chemical classes, consisting of the known developmental toxicants 5-fluorouracil, all-trans retinoic acid and valproic acid, as well as the negative control compounds ascorbic acid and folic acid. In addition, the fungicides epoxiconazole and prochloraz, and three perfluoroalkyl substances (PFAS), PFOS, PFOA and GenX were tested. Generally, the PluriLum assay displayed higher sensitivity when compared to the PluriBeat assay. For several compounds the luminescence readout of the PluriLum assay showed effects not detected by the PluriBeat assay, including two PFAS compounds and the two fungicides. Overall, we find that the PluriLum assay has the potential to provide a fast and objective detection of developmental toxicants and has a level of sensitivity that is comparable to or higher than other in vitro assays also based on human stem cells and cardiomyocyte differentiation for assessment of developmental toxicity.

Bioaccumulation Characteristics of Typical Perfluoroalkyl Compounds in Alfalfa Under Salt Stress.

Medicago sativa, commonly known as alfalfa, is widely distributed worldwide, known for its strong stress resistance and well-developed root system, making it an important plant in ecological restoration research. To investigate the absorption and transport characteristics of alfalfa for typical perfluoroalkyl substances (PFAS) under salt stress, a 30-day indoor greenhouse experiment was conducted. The results showed that alfalfa exhibited varying degrees of absorption and transport for the selected PFAS. The highest BCF (Bioconcentration Factor) for shoot tissue reached 725.4 (for PFBA), and the highest TF (Translocation Factor) reached 53.8 (for PFPeA). Different PFAS compounds exhibited distinct bioaccumulation behaviors, with short-chain PFAS more readily entering the plant's root system and being transported upwards, while long-chain PFAS tended to adsorb to the surface of the root system. Furthermore, salt stress did not significantly affect the uptake of PFAS by alfalfa. This suggests that alfalfa is salt-tolerant and holds great potential for ecological restoration in short-chain PFAS-contaminated sites.

Decoding PFAS contamination via Raman spectroscopy: A combined DFT and machine learning investigation

In this study, density function theory (DFT) is employed to compute Raman spectra of 40 important Perfluoroalkyl substances (PFASs) as listed in Draft Method 1633 by U.S. Environmental Protection Agent. A systematic comparison of their spectral features is conducted, and Raman peaks and vibrational modes are identified. The Raman spectral regions for the main chemical bonds (such as C-C, CF2 & CF3, O-H) and main functional groups (such as -COOH, -SO3H, -C2H4SO3H, and -SO2NH2) are identified and compared. The impacts of branching location in isomer, molecular chain length, and functional groups on the Raman spectra are analyzed. Particularly, the isomers of PFOA alter the peak locations slightly in wavenumber regions of 200 – 800 and 1000 – 1400 cm−1, while for PFOS, spectral features in the 230 – 360, 470 – 680, and 1030 – 1290 cm−1 regions exhibit significant difference. The carbon chain length can significantly increase the number of Raman peaks, while different functional groups give significantly different peak locations. To facilitate differentiation, a spectral database is constructed by introducing controlled noise into the DFT-computed Raman spectra. Subsequently, two chemometric techniques, principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE), are applied to effectively distinguish among these spectra, both for 40 PFAS compounds and the isomers. The findings demonstrate the promising potential of combining Raman spectroscopy with advanced spectral analysis methods to discriminate between distinct PFAS compounds, holding significant implications for improved PFAS detection and characterization methodologies.

Perfluoroalkyl substances exposure alters stomatal opening and xylem hydraulics in willow plants

Climate change and pollution are increasingly important stress factors for life on Earth. Dispersal of poly- and perfluoroalkyl substances (PFAS) are causing worldwide contamination of soils and water tables. PFAS are partially hydrophobic and can easily bioaccumulate in living organisms, causing metabolic alterations. Different plant species can uptake large amounts of PFAS, but little is known about its consequences for the plant water relation and other physiological processes, especially in woody plants. In this study, we investigated the fractionation of PFAS bioaccumulation from roots to leaves and its effects on the conductive elements of willow plants. Additionally, we focused on the stomal opening and the phytohormonal content. For this purpose, willow cuttings were exposed to a mixture of 11 PFAS compounds and the uptake was evaluated by LC-MS/MS. Stomatal conductance was measured and the xylem vulnerability to air embolism was tested and further, the abscisic acid and salicylic acid contents were quantified using LC-MS/MS. PFAS accumulated from roots to leaves based on their chemical structure. PFAS-exposed plants showed reduced stomatal conductance, while no differences were observed in abscisic acid and salicylic acid contents. Interestingly, PFAS exposure caused a higher vulnerability to drought-induced xylem embolism in treated plants. Our study provides novel information about the PFAS effects on the xylem hydraulics, suggesting that the plant water balance may be affected by PFAS exposure. In this perspective, drought events may be more stressful for PFAS-exposed plants, thus reducing their potential for phytoremediation.

Perfluoroalkyl substances in Romanian wastewater treatment plants: Transfer to surface waters, environmental and human risk assessment

The current study aimed to determine the concentration levels of nine perfluoroalkyl substances (PFAS) in the five most significant Romanian wastewater treatment plants (WWTPs) and their transfer to natural receivers. The analytes were concentrated using a solid-phase extraction/ultrasonic-assisted extraction procedures and then selectively quantified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) using electrospray ionization. In most of the wastewater samples investigated, the dominant compounds were perfluoropentanoic acid (PFPeA), perfluorooctanoic acid (PFOA), and perfluorooctansulfonate acid (PFOS), with the maximum concentration range between 105 and 316 ng/L in influents, 14.8–31.3 ng/L in effluents and removal efficiencies higher than 80 % for all selected PFAS compounds. In sewage sludge samples, PFOA and PFOS were the majority substances, with values up to 35.8 ng/g dw for PFOA and 27.8 ng/g dw for PFOS. PFOA and PFOS achieved the maximum levels by estimating mass loading and emission levels. As a result, 237 mg/day/1000 people of PFOA and 95.5 mg/day/1000 people of PFOS are entering daily in the WWTPs, while up to 31 mg/day/1000 people of PFOA and up to 13.6 mg/day/1000 people of PFOS are discharged daily into the natural emissaries. Human risk assessment shows that PFOA and PFOS are low to high risk for all age and gender categories. Children are the most exposed to PFOA and PFOS contamination in drinking water. Environmental risk assessment reveals that PFOA exhibits a low risk for some insect species, PFOS - a low risk for freshwater shrimps and a medium risk for midges, while perfluoroundecanoic acid (PFNuDA) could have a low to medium risk for midges. No assessment studies regarding the environmental and human risk of PFAS have been performed in Romania.

Room Temperature Defluorination of Poly(tetrafluoroethylene) by a Magnesium Reagent

Perfluoroalkyl substances (PFAS) are pervasive in the environment. The largest single use material within the PFAS compound class is poly(tetrafluoroethylene) (PTFE), a robust and chemically resistant polymer. Despite their widespread use and serious concerns about their role as pollutants, methods for repurposing PFAS are rare. Here we show that a nucleophilic magnesium reagent reacts with PTFE at room temperature, generating a molecular magnesium fluoride which is easily separated from the surface-modified polymer. The fluoride in turn can be used to transfer the fluorine atoms to a small array of compounds. This proof-of-concept study demonstrates that the atomic fluorine content of PTFE can be harvested and reused in chemical synthesis.

Study on Pollution Characteristics of Perfluoroalkyl Substances (PFASs) in Shallow Groundwater

Perfluoroalkyl substances (PFASs) in shallow groundwater are increasingly being studied due to the global occurrence, environment persistence, bioaccumulation, and potential human health risk. In this research, 16 PFAS (11 perfluorinated carboxylic acids and 5 perfluorinated sulfonic acids) concentrations in groundwater were quantified to obtain information on geographical distribution and PFAS detection pattern for 4 years in South Korea. In the results, groundwater PFAS concentration ranged from non-detectable to average 45.2 ng/L (sum of PFASs). The major PFAS compounds were perfluorooctanoic acid (PFOA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS). The short chain (C < 8) PFASs were more prevalent than long chain (C > 8) PFASs in shallow groundwater. However, the detection patterns of 15 PFASs were different for each aquifer. Subsequently, through a health risk assessment, a non-carcinogenic risk level through ingestion, inhalation, and dermal contact for PFOA and PFOS was determined at 10−1, and it presents the need for PFAS management of groundwater.

Multiclass method to determine emerging pollutants in bats using a non-invasive approach based on guano matrix

Emerging pollutants have been ubiquitously found in environmental compartments, while there is scarce information about these substances and their effects on health status in wild terrestrial mammals. Bat species are very sensitive animals to any changes in the environment and are considered one of the best bioindicators of the quality of the environment to terrestrial wildlife. To acquire a better knowledge of the environmental exposure to these animals, a multiclass method is proposed to determine 20 emerging pollutants (six perfluoroalkyl substances (PFAS), four parabens (PB), four benzophenones (BP), a plasticizer (BPA), and five surfactants (four linear alkylbenzene sulfonates (LAS) and nonylphenol (NP)) in bats using a non-invasive approach based on guano matrix. Sample treatment involved ultrasonic solvent extraction and dispersive solid phase extraction prior to analysis in a single run with liquid chromatography-tandem mass spectrometry. The main variables affecting the extraction and clean-up steps were evaluated using single and multivariate strategies. Under the optimized conditions, satisfactory analytical characteristics in terms of linearity, recoveries (>80 %), precision (RSD < 24 %) and method quantification limits (from 0.01 to 64 ng/g dry weight) were obtained. Furthermore, and as a proof of concept, guano samples from a bat reference population were collected from a colony located in Brenna village, in south Poland. The results confirm the exposure of wild bats to emerging pollutants (LAS, PFAS, and PB compounds were frequently detected in the samples) and the suitability of the bat guano matrix for understanding the environmental exposure in terrestrial mammals.

Perfluoroalkyl Substances in the Circumpolar Arctic and Northern Populations

Persistent organic pollutants including perfluoroalkyl substances (PFAS) are globally ubiquitous contaminants transported with sea currents and atmospheric movements, accumulating in the environment, food-chain, animals and humans and possess a potential health risk including the immune-, neurobehavioral-, and reproductive systems. The profile and concentrations found in humans elicit regional differences that might be related to the countries PFAS use, production, lifestyle, and diet. In the Arctic, the PFAS compounds were never produced or used, however, the Arctic Indigenous and northern populations consuming traditional diet including marine mammals at the top of the food-chain (e.g., whales, seals, polar bears) are particularly exposed to PFAS. This mini review gives a short overview on health effects in the circumpolar Arctic populations and aims to compare the PFAS levels in the Arctic with primary focus on the period 2010-20 and relate the levels with the general national country populations. As expected, regional concentration and profile differences were found over the circumpolar Arctic with the highest level found in Greenland. Moreover, in general the regulated PFAS (perfluorooctane sulfonate, perfluoro-octanoate, perfluorohexane sulfonate) tend to decrease and the unregulated PFAS (e.g., perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid) increases in concentration during this period. Generally, the PFAS levels were higher in men than women increasing with age. For most Arctic regions, the PFAS levels were higher compared to the general national country populations.

A juxtaposed review on adsorptive removal of PFAS by metal-organic frameworks (MOFs) with carbon-based materials, ion exchange resins, and polymer adsorbents

The removal of poly- and perfluoroalkyl substances (PFAS) from the aquatic environment is a universal concern due to the adverse effects of these substances on both the environment and public health. Different adsorbents, including carbon-based materials, ion exchange resins, biomaterials, and polymers, have been used for the removal of short-chain (C < 6) and long-chain (C > 7) PFAS from water with varying performance. Metal-organic frameworks (MOFs), as a new generation of adsorbents, have also been recently used to remove PFAS from water. MOFs provide unique properties such as significantly enhanced surface area, structural tunability, and improved selectivity compared to conventional adsorbents. However, due to various types of MOFs, their complex chemistry and morphology, different PFAS compounds, lack of standard adsorption test, and different testing conditions, there are inconclusive and contradictory findings in the literature. Therefore, this review aims to provide critical analysis of the performance of different types of MOFs in the removal of long-chain (C > 7), short-chain (C < 6), and ultra-short-chain (C < 3) PFAS and comprehensively study the efficiency of MOFs for PFAS removal in comparison with other adsorbents. In addition, the adsorption mechanisms and kinetics of PFAS components on different MOFs, including Materials of Institute Lavoisier (MIL), Universiteit of Oslo (UiO), Zeolitic imidazolate frameworks (ZIFs), Hong Kong University of Science and Technology (HKUST), and other hybrid types of MOF were discussed. The study also discussed the effect of environmental factors such as pH and ionic strength on the adsorption of PFAS on MOFs. In addition to the adsorption process, the reusability and regeneration of MOFs in the PFAS removal process are discussed. Finally, challenges and future outlooks of the utility of MOFs for PFAS removal were discussed to inspire future critical research efforts in removing PFAS.

The Breast Milk Perfluorome is Associated with Infant Growth in the First Year of Life

BACKGROUND AND AIM: Early life exposure to poly- and perfluoroalkyl substances (PFAS) has significant obesogenic effects that are manifested in early life. However, PFAS examined do not include the wide range of PFAS used in commercial applications. METHODS: This pilot included 56 Hispanic mother-child pairs from Southern California. Maternal and infant characteristics were assessed, including infant weight, length, and fat mass. All mothers were breastfeeding, and breast milk was collected at 1-month postpartum. The perfluorome was characterized using untargeted high-resolution mass spectrometry. Organofluorine compounds were identified using the EPA CompTox Dashboard. Multivariable linear and logistic regression analyses were used to examine associations between PFAS with growth measures (12-months, change in first year, rapid growth) after adjusting for infant age, sex, pre-pregnancy BMI, gestational age, and formula feedings. Results are reported for associations with p&amp;#x3c;0.05 and were considered statistically significant using a false discovery rate (FDR) of 20%. RESULTS: 484 suspect PFAS compounds were detected in &amp;#x2265;75% of samples. PFAS were associated with 12-month weight [n(%): 10(2.1%) positive, 12(2.5%) negative], change in weight [10(2.1%) positive, 22(4.5%) negative], 12-month length [21(4.3%) positive, 17(3.5%) negative] change in length [22(4.5%) positive, 25(5.2%) negative], 12-month fat mass [9(1.9%) positive, 12(2.5%) negative], and change in fat mass [18(3.7%) positive, 21(4.3%) negative]. Additionally, 12(2.5%) and 13(2.7%) of PFAS compounds were associated with an increased (OR=2.0-3.8) and decreased odds (OR=0.28-0.47) of rapid growth in the first, respectively. After FDR, three compounds, each detected in &amp;#x3e;98% of samples, were associated with change in length (q=0.01; n=2 positive, n=1 negative). Tentative annotations of these compounds identified novel PFAS, including methyl 4,4,5,5,5-pentafluoropent-2-ynoate3,4,4,5,5-Pentafluoro-2-methoxycyclopent-2-en-1-one, ethyl [5-(heptafluoropropyl)-1-methyl-1H-pyrazol-3-yl]acetate, and ethyl 2-acetyl-4,4,5,5,5-pentafluoro-3-oxopentanoate. CONCLUSIONS: Results from this pilot suggest that a wide range of PFAS are present in human breast milk, which may impact infant growth in the first year of life. KEYWORDS: breast milk, PFAS, infants

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.

A Bad Start in Life? Maternal Transfer of Legacy and Emerging Poly- and Perfluoroalkyl Substances to Eggs in an Arctic Seabird.

In birds, maternal transfer is a major exposure route for several contaminants, including poly- and perfluoroalkyl substances (PFAS). Little is known, however, about the extent of the transfer of the different PFAS compounds to the eggs, especially for alternative fluorinated compounds. In the present study, we measured legacy and emerging PFAS, including Gen-X, ADONA, and F-53B, in the plasma of prelaying black-legged kittiwake females breeding in Svalbard and the yolk of their eggs. We aimed to (1) describe the contaminant levels and patterns in both females and eggs, and (2) investigate the maternal transfer, that is, biological variables and the relationship between the females and their eggs for each compound. Contamination of both females and eggs were dominated by linPFOS then PFUnA or PFTriA. We notably found 7:3 fluorotelomer carboxylic acid─a precursor of long-chain carboxylates─in 84% of the egg yolks, and provide the first documented finding of ADONA in wildlife. Emerging compounds were all below the detection limit in female plasma. There was a linear association between females and eggs for most of the PFAS. Analyses of maternal transfer ratios in females and eggs suggest that the transfer is increasing with PFAS carbon chain length, therefore the longest chain perfluoroalkyl carboxylic acids (PFCAs) were preferentially transferred to the eggs. The mean ∑PFAS in the second-laid eggs was 73% of that in the first-laid eggs. Additional effort on assessing the outcome of maternal transfers on avian development physiology is essential, especially for PFCAs and emerging fluorinated compounds which are under-represented in experimental studies.

Thermal decomposition of heptafluoropropylene-oxide-dimer acid (GenX)

Incineration appears as a viable strategy in the disposal of the notorious perfluoroalkyl substances (PFASs) in a process that typically leads to fluorine mineralization. Central in the design of such operation is to comprehend the underlying chemical mechanisms that dictate thermal fragmentation of PFASs into smaller perfluorinated cuts and HF. Among notable short-chain PFASs entities is the heptafluoropropylene-oxide-dimer acid (HFPO-DA, C5F11C(O)OH), commercially known as GenX synthesized as a possible replacement of other PFASs compounds. However, reaction pathways that underpin the degradation of GenX at temperatures relevant to its decomposition in incinerators (i.e., cement kilns), remain unknown. Herein, we map out all plausible initial reactions that govern the thermal decomposition of GenX. Simultaneous elimination of HF and CO2 appears as the kinetically most favored channel with an accessible activation enthalpy of ∼62.0 kcal/mol. Fission of the ether linkage in the 1,1,1,2,2,3,3-heptafluoro-3-[(1-fluoroethenyl)oxy] propane molecule (that forms after HF/CO2 elimination) affords a wide array of CnFm cuts, most notably CF2 at elevated temperatures. Constructed kinetic model plots temperature-dependent profiles of important species. It is predicted that GenX to commence decomposition around 700 K at a residence time of 2.0 s, a value that is generally applied in incinerators. Findings from the study call to further investigate interactions between the predicted major fluorine carriers (HF and CF2) and other constituents encountered in relevant incineration mediums, most notably, calcium hydroxides and polymeric materials.

Cheap and Simple Electrochemical Sensors with Closed-Cell MIP-Coated Bipolar Electrode Arrays for Sub-Ppb Detection of PFOS in Water

Growing public awareness of the health risks associated with long-term exposure to poly- and perfluoroalkyl substances (PFAS) has necessitated the development of low-cost, point of use, and accessible methods for detection in water. Efforts to develop such methods have been stymied by their very low concentrations (part per trillion level) and remarkable chemical stability. Recently, our group has developed a new technique termed optical anodic stripping voltammetry (o-ASV) which couples a closed-cell continuous bipolar electrochemical (BPE) sensor with cathodic electrochemiluminescence (ECL) reporting for the simple, rapid, and point-of-use detection of heavy metal ions in water. The work presented here, on the other hand, is aimed at adapting this same sensor transduction scheme to the quantitation of PFAS compounds. The primary challenge is accommodating the electrochemical inactivity exhibited by most PFAS compounds. This presentation will describe development of a molecular imprint polymer (MIP) layer on the surface of the sensor BPE to promote both selectivity and sensitivity in detection. The MIP layer works in combination with a proxy redox probe, ferrocene carboxylate (FcCOOH), to transduce the current signal to an optical readout that can be read with a digital camera like those on most modern cellular phones. This presentation will focus on describing the nature of the sensor transduction principle as applied to non-redox active PFAS compounds like perfluorooctanoic sulfonate (PFOS). A specific discussion of the operative mechanistic components of detection will be addressed, including the interplay between molecular adsorption, diffusion, and electrochemical transformation. Details of the stability and functional longevity of the electropolymerized MIP layer will be discussed along with its application to other isomorphic PFAS compounds. Finally, a new simple device fabrication procedure will be highlighted as it pertains to the open-source production of these novel sensors.

Rain Amplification of Persistent Organic Pollutants.

Scavenging of gas- and aerosol-phase organic pollutants by rain is an efficient wet deposition mechanism of organic pollutants. However, whereas snow has been identified as a key amplification mechanism of fugacities in cold environments, rain has received less attention in terms of amplification of organic pollutants. In this work, we provide new measurements of concentrations of perfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and polycyclic aromatic hydrocarbons (PAHs) in rain from Antarctica, showing high scavenging ratios. Furthermore, a meta-analysis of previously published concentrations in air and rain was performed, with 46 works covering different climatic regions and a wide range of chemical classes, including PFAS, OPEs, PAHs, polychlorinated biphenyls and organochlorine compounds, polybromodiphenyl ethers, and dioxins. The rain–aerosol (KRP) and rain–gas (KRG) partition constants averaged 105.5 and 104.1, respectively, but showed large variability. The high field-derived values of KRG are consistent with adsorption onto the raindrops as a scavenging mechanism, in addition to gas–water absorption. The amplification of fugacities by rain deposition was up to 3 orders of magnitude for all chemical classes and was comparable to that due to snow. The amplification of concentrations and fugacities by rain underscores its relevance, explaining the occurrence of organic pollutants in environments across different climatic regions.

Prenatal Exposure to Perfluoroalkyl Substances and Mental Health in Childhood

BACKGROUND AND AIM: Epidemiological studies have evaluated the effect of prenatal exposure to perfluoroalkyl substances (PFAS) on neurobehavioral and cognitive endpoints in childhood, but a research focus on mental health is lacking. We evaluated the associations between prenatal PFAS exposure and mental health including depressive symptoms, physical or emotional stress, and psychosis-like experience in children at age 11. METHODS: Using pooled samples in the Danish National Birth Cohort established between 1996 and 2002 (N=2,250), we estimated the associations between concentrations of six types of PFAS in maternal plasma (median, 8 gestational weeks) and child self-report mental health outcomes using validated questionnaires. Binary classifications (with or without moderate/severe symptoms) for each of the outcomes and continuous outcome variables were analyzed. We used unconditional logistic regressions to estimate the adjusted odds ratio (OR) and 95% confidence interval (CI) for the binary outcomes according to log2-transformed PFAS concentrations and PFAS tertiles. PFAS mixture by using the weighted-quantile-sum index was conducted. Analyses were repeated using negative binomial regressions for continuous count outcome variables. Sex-specific analyses were conducted. RESULTS:The highest exposure tertile for perfluorooctanoic acid (OR=1.34, 95% CI: 1.06, 1.71), perfluorohexane sulfonate (OR=1.43, 95% CI: 1.06, 1.92) and perfluoroheptane sulfonate (OR=1.37, 95% CI: 1.02, 1.84) were associated with elevated physical or emotional stress in childhood. The WQS index for PFAS mixture was also positively associated with stress in childhood (OR=1.21, 95% CI: 1.05, 1.40). There were no consistent associations found for these PFAS compounds and depressive symptoms or psychosis-like experience. Findings from negative binomial regressions were similar. There were also no apparent differences in analyses stratified by sex. CONCLUSIONS:Higher prenatal levels of three PFAS compounds and PFAS mixtures might influence physical and emotional stress in childhood. More research of fetal exposures to environmental pollutants and mental health risk in the offspring would be needed. KEYWORDS: PFAS, Mental health outcomes, Children's environmental health, Environmental epidemiology

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 × 103ng/L in water samples and 9.13 to 850ng/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.

PFAS Exposure Pathways for Humans and Wildlife: A Synthesis of Current Knowledge and Key Gaps in Understanding.

We synthesize current understanding of the magnitudes and methods for assessing human and wildlife exposures to poly- and perfluoroalkyl substances (PFAS). Most human exposure assessments have focused on 2 to 5 legacy PFAS, and wildlife assessments are typically limited to targeted PFAS (up to ~30 substances). However, shifts in chemical production are occurring rapidly, and targeted methods for detecting PFAS have not kept pace with these changes. Total fluorine measurements complemented by suspect screening using high-resolution mass spectrometry are thus emerging as essential tools for PFAS exposure assessment. Such methods enable researchers to better understand contributions from precursor compounds that degrade into terminal perfluoroalkyl acids. Available data suggest that diet is the major human exposure pathway for some PFAS, but there is large variability across populations and PFAS compounds. Additional data on total fluorine in exposure media and the fraction of unidentified organofluorine are needed. Drinking water has been established as the major exposure source in contaminated communities. As water supplies are remediated, for the general population, exposures from dust, personal care products, indoor environments, and other sources may be more important. A major challenge for exposure assessments is the lack of statistically representative population surveys. For wildlife, bioaccumulation processes differ substantially between PFAS and neutral lipophilic organic compounds, prompting a reevaluation of traditional bioaccumulation metrics. There is evidence that both phospholipids and proteins are important for the tissue partitioning and accumulation of PFAS. New mechanistic models for PFAS bioaccumulation are being developed that will assist in wildlife risk evaluations. Environ Toxicol Chem 2021;40:631-657. © 2020 SETAC.