Modeling the global fate and transport of perfluorooctane sulfonate (PFOS) and precursor compounds in relation to temporal trends in wildlife exposure

Development and Evaluation of Aquatic and Terrestrial Food Web Bioaccumulation Models for Per- and Polyfluoroalkyl Substances

There is a need for reliable models to predict the food web bioaccumulation and assess ecological and human health risks of per- and polyfluoroalkyl substances (PFAS). This present study presents (i) the development of novel mechanistic aquatic and terrestrial food web bioaccumulation models for PFAS and (ii) an evaluation of model performance using available laboratory and field data. Model predictions of laboratory-measured bioconcentration factors and field-based bioaccumulation factors of PFAS in fish were in good agreement with observed data as measured by the mean model bias (MB), representing systematic over- or under-estimation and the standard deviation of the MB, representing general uncertainty. The models provide a mechanistic framework for evaluating the combined effect of simultaneously occurring uptake and elimination processes and indicate food web-specific magnification of PFAS, with the highest degree of biomagnification occurring in food webs composed of air-breathing wildlife. Albumin-water, structural protein-water, membrane-water distribution coefficients, and renal clearance rate are among the most important model parameters. With further development and testing, these models may be useful for future PFAS screening and risk assessment initiatives and advance bioaccumulation studies of PFAS by providing a mechanistic framework for PFAS bioaccumulation.

Transport and dispersion of PFOA and PFOS in the Black Sea

A 3-D transport and dispersion model was applied to study the recent past and future dynamics of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) concentrations in the Black Sea for the 2016-2030 period. The modelled surface concentrations show a distinct seasonal behaviour, shaped by winter to spring convective mixing. A significant increasing long-term trend in PFOS concentrations is established, with concentrations in water layers 200 m below the surface increasing at 4-8% per year. Driving mechanisms for PFOA and PFOS transport and accumulation in the subsurface and deeper layers are the cooling of the surface water in winter and the transport of water masses from the North Western Shelf (NWS) of the Black Sea. A simulated 50% phase-out of PFOA and PFOS from 2020 to 2030 shows a 21% reduction in PFOA, while PFOS continues to increase.

Sn/Sb-assisted alum sludge electrodes for eliminating hydrophilic organic pollutants in self-produced H2O2 electro-Fenton system: Insights into the co-oxidation mediated by 1O2 and •OH(ads)

Few reports have focused on using particle electrodes with polar adsorbent properties in heterogeneous electro-Fenton (EF) system to improve the degradation of hydrophilic organic pollutants (HLOPs). In this study, a hydrophilic electrode Sn-Sb/AS was prepared by supporting metals Sn and Sb on alum sludge (AS), which can effectively degrade 91.68%, 92.54%, 89.62%, and 96.24% of the four types of HLOPs, chlorpyrifos (CPF), atrazine (ATZ), diuron (DIU), and glyphosate (PMG), respectively, within 40 min. The mineralization rates were 82.37%, 78.93%, 73.98%, and 85.65% for CPF, ATZ, DIU, and PMG, respectively. Based on the analysis of Electron Paramagnetic Resonance test, quenching test, and identified anthracene endoperoxide, the degradation at the cathode was attributed to non-radical oxidation via interaction with 1O2. In contrast, the anodic oxidation occurred via direct electron transfer at the anode and/or oxidation via interaction with adsorbed •OH (•OHads) around the particle electrodes. Furthermore, the reaction sites were calculated by Density functional theory (DFT) and Fukui function, corresponding to the electrophilic attack (fA-) of 1O2 and anodic direct oxidation, besides, the radical attack (fA0) of •OH(ads). Herein, this study proposes a targeted elimination strategy for HLOPs in wastewater treatment using particle electrodes with polar adsorbent properties in EF system.

Accumulation features and temporal trends (2002-2015) for legacy and emerging per- and polyfluoroalkyl substances (PFASs) in finless porpoises bycaught off Korean coasts

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) were measured in livers of finless porpoises (Neophocaena asiaeorientalis; n = 167) collected in Korean waters from 2002 to 2015 to investigate their occurrence, bioaccumulation feature, temporal trends, and ecotoxicological implications. Perfulorooctane sulfonate (PFOS), perfluoroundecanoate (PFUnDA), and perfluorotridecanoate (PFTrDA) were the predominant PFASs found in the porpoises. The concentration of 6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B), an alternative to PFOS, was comparable to that of PFTrDA. Perfluorooctane sulfonamide (FOSA), a precursor of PFOS, was also detected in all the porpoises examined. All PFASs, including F-53B, accumulated to higher concentrations in immature porpoises compared with mature specimens, implying substantial maternal transfer and limited metabolizing capacity for PFASs. A significant correlation was observed between PFOS and F-53B concentrations, indicating similar bioaccumulation processes. Based on prenatal exposure and toxicity, F-53B is an emerging contaminant in marine ecosystems. Significantly increasing trends were observed in the concentrations of sulfonates, carboxylates, and F-53B between 2002/2003 and 2010, whereas the FOSA concentration significantly decreased. During 2010-2015, decreasing trends were observed in the concentrations of FOSA and sulfonates, whereas concentrations of carboxylate and F-53B increased without statistical significance, likely due to a gap for the implementation of regulatory actions between sulfonates and carboxylates. Although PFOS and PFOA were found to pose little health risk to porpoises, the combined toxicological effects of other contaminants should be considered to protect populations and to mitigate PFAS contamination in marine ecosystems.

The perils of poly- and perfluorinated chemicals on the reproductive health of humans, livestock, and wildlife

Poly- and perfluoroalkyl substances (PFAS) are a prominent class of persistent synthetic compound. The widespread use of these substances in various industrial applications has resulted in their pervasive contamination on a global scale. It is therefore concerning that PFAS have a propensity to accumulate in bodily tissues whereupon they have been linked with a range of adverse health outcomes. Despite this, the true extent of the risk posed by PFAS to humans, domestic animals, and wildlife remains unclear. Addressing these questions requires a multidisciplinary approach, combining the fields of chemistry, biology, and policy to enable meaningful investigation and develop innovative remediation strategies. This article combines the perspectives of chemists, soil scientists, reproductive biologists, and health policy researchers, to contextualise the issue of PFAS contamination and its specific impact on reproductive health. The purpose of this article is to describe the challenges associated with remediating PFAS-contaminated soils and waters and explore the consequences of PFAS contamination on health and reproduction. Furthermore, current actions to promote planetary health and protect ecosystems are presented to instigate positive social change among the scientific community.

Hepatotoxicity induced in rats by chronic exposure to F-53B, an emerging replacement of perfluorooctane sulfonate (PFOS)

A plethora of studies have shown the prominent hepatotoxicity caused by perfluorooctane sulfonate (PFOS), yet the research on the causality of F-53 B (an alternative for PFOS) exposure and liver toxicity, especially in mammals, is largely limited. To investigate the effects that chronic exposure to F-53 B exert on livers, in the present study, male SD rats were administrated with F-53 B in a certain dose range (0, 1, 10, 100, 1000 μg/L, eight rats per group) for 6 months via drinking water and the hepatotoxicity resulted in was explored. We reported that chronic exposure to 100 and 1000 μg/L F-53 B induced remarkable histopathological changes in liver tissues such as distinct swollen cells and portal vein congestion. In addition, the increase of cytokines IL-6, IL-2, and IL-8 upon long-term administration of F-53 B demonstrated the high level of inflammation. Moreover, F-53 B exposure was revealed to disrupt the lipid metabolism in the rat livers, mainly manifesting as the upregulation of some proteins involved in lipid synthesis and degradation, including ACC, FASN, SREBP-1c as well as ACOX1. These findings provided new evidence for the adverse effects caused by chronic exposure to F-53 B in rodents. It is crucial for industries, regulatory agencies as well as the public to remain vigilant about the adverse health effects associated with the emerging PFOS substitutes such as F-53 B. Implementation of regular monitoring and risk assessments is of great importance to alleviate environmental concerns towards PFOS alternatives exposure, and furthermore, to minimize the latent health risks to the public health.

Simulating behavior of perfluorooctane sulfonate (PFOS) in the mainstream of a river system with sluice regulations

Perfluorooctane sulfonate (PFOS) is a persistent, anionic and ubiquitous contaminant that undergoes long-range transport within the environment. Its behavior has attracted wide-range academic and regulatory attention. In this article, a mass balance model was employed to simulate PFOS concentrations in the mainstream of Haihe River water system, encompassing sluices and artificial rivers. The dynamic simulation of PFOS concentrations in both sediment and freshwater took into account fluctuations in PFOS emissions, water levels and water discharge. Furthermore, the study delved into exploring the impacts of sluices and artificial rivers on the behavior of PFOS. The simulated concentrations of PFOS in steady state agreed with the measured concentrations in surveys carried out in Nov. 2019, July 2020, Oct. 2020, and June 2021. Every year, approximately 24 kg PFOS was discharged into the Bohai Sea with Chaobai New River being the largest contributor for 44 %. Moreover, the transport of PFOS in the original rivers is likely to be restricted by sluices and replaced by artificial rivers. Monte Carlo analysis showed that model predictions of PFOS concentrations in sediment were subject to greater uncertainty than those in freshwater as the former is impacted by more parameters, such as density of sediment. This study provides a scientific basis for the local government to manage and control PFOS.

Comparison of the PFAS and physical-chemical parameter fluctuations between an ash landfill and a MSW landfill

Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (rs > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑26PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills.

Early life exposure to perfluorooctanesulfonate (PFOS) impacts vital biological processes in Xenopus laevis: Integrated morphometric and transcriptomic analyses

Perfluorooctanesulfonate (PFOS) is a ubiquitous environmental pollutant associated with increasing health concerns and environmental hazards. Toxicological analyses of PFOS exposure are hampered by large interspecies variations and limited studies on the mechanistic details of PFOS-induced toxicity. We investigated the effects of PFOS exposure on Xenopus laevis embryos based on the reported developmental effects in zebrafish. X. laevis was selected to further our understanding of interspecies variation in response to PFOS, and we built upon previous studies by including transcriptomics and an assessment of ciliogenic effects. Midblastula-stage X. laevis embryos were exposed to PFOS using the frog embryo teratogenesis assay Xenopus (FETAX). Results showed teratogenic effects of PFOS in a time- and dose-dependent manner. The morphological abnormalities of skeleton deformities, a small head, and a miscoiled gut were associated with changes in gene expression evidenced by whole-mount in situ hybridization and transcriptomics. The transcriptomic profile of PFOS-exposed embryos indicated the perturbation in the expression of genes associated with cell death, and downregulation in adenosine triphosphate (ATP) biosynthesis. Moreover, we observed the effects of PFOS exposure on cilia development as a reduction in the number of multiciliated cells and changes in the directionality and velocity of the cilia-driven flow. Collectively, these data broaden the molecular understanding of PFOS-induced developmental effects, whereby ciliary dysfunction and disrupted ATP synthesis are implicated as the probable modes of action of embryotoxicity. Furthermore, our findings present a new challenge to understand the links between PFOS-induced developmental toxicity and vital biological processes.

Inputs, amplification and sinks of perfluoroalkyl substances at coastal Antarctica

The sources, biogeochemical controls and sinks of perfluoroalkyl substances, such as perfluoroalkyl acids (PFAAs), in polar coastal regions are largely unknown. These were evaluated by measuring a large multi-compartment dataset of PFAAs concentrations at coastal Livingston and Deception Islands (maritime Antarctica) during three austral summers. PFAAs were abundant in atmospheric-derived samples (aerosols, rain, snow), consistent with the importance of atmospheric deposition as an input of PFAAs to Antarctica. Such PFAAs deposition was unequivocally demonstrated by the occurrence of PFAAs in small Antarctic lakes. Several lines of evidence supported the relevant amplification of PFAAs concentrations in surface waters driven by snow scavenging of sea-spray aerosol-bound PFAAs followed by snow-melting. For example, vertical profiles showed higher PFAAs concentrations at lower-salinity surface seawaters, and PFAAs concentrations in snow were significantly higher than in seawater. The higher levels of PFAAs at Deception Island than at Livingston Island are consistent with the semi-enclosed nature of the bay. Concentrations of PFOS decreased from 2014 to 2018, consistent with observations in other oceans. The sink of PFAAs due to the biological pump, transfer to the food web, and losses due to sea-spray aerosols alone are unlikely to have driven the decrease in PFOS concentrations. An exploratory assessment of the potential sinks of PFAAs suggests that microbial degradation of perfluoroalkyl sulfonates should be a research priority for the evaluation of PFAAs persistence in the coming decade.

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

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

Improved total organic fluorine methods for more comprehensive measurement of PFAS in industrial wastewater, river water, and air

Per- and polyfluoroalkyl substances (PFAS) are high-profile environmental contaminants, many having long persistence in the environment and widespread presence in humans and wildlife. Following phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in North America and restrictions in Europe, PFAS replacements are now widely found in the environment. While liquid chromatography (LC)-mass spectrometry (MS) is typically used for measurement, much of the PFAS is missed. To more comprehensively capture organic fluorine, we developed sensitive and robust methods using activated carbon adsorption, solid phase extraction, and combustion ion chromatography (CIC) to measure total organic fluorine (TOF) in industrial wastewaters, river water, and air. Two extraction techniques, adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF), were optimized and compared using 39 different PFAS, including replacements, such as GenX and perfluorobutanesulfonate. Our AOF method achieves 46-112% and 87% recovery for individual PFAS and PFAS mixtures, respectively, with 0.5 µg/L limit of detection (LOD) for a 50 mL sample volume and a 0.3 μg/L LOD for a 500 mL sample volume . Our EOF method achieves 72-99% and 91% recovery for individual PFAS and PFAS mixtures, respectively, with 0.2 µg/L LOD for a 500 mL sample volume and 0.1 μg/L LOD for 1200 mL. In addition to 39 anionic PFAS, two zwitterionic PFAS and two neutral PFAS were evaluated using the optimized TOF methods. Substantially higher TOF values were measured in industrial wastewater, river water, and air samples compared to LC-MS/MS, demonstrating how TOF methods provided a more comprehensive measurement of the total PFAS present, capturing known and unknown organic fluorine.

Horizontal and Vertical Distribution of Perfluoroalkyl Acids (PFAAs) in the Water Column of the Atlantic Ocean

Perfluoroalkyl acids (PFAAs) are widely distributed in the oceans which are their largest global reservoir, but knowledge is limited about their vertical distribution and fate. This study measured the concentrations of PFAAs (perfluoroalkyl carboxylic acids (PFCAs) with 6 to 11 carbons and perfluoroalkanesulfonic acids (PFSAs) with 6 and 8 carbons) in the surface and deep ocean. Seawater depth profiles from the surface to a 5000 m depth at 28 sampling stations were collected in the Atlantic Ocean from ∼50° N to ∼50° S. The results demonstrated PFAA input from the Mediterranean Sea and the English Channel. Elevated PFAA concentrations were observed at the eastern edge of the Northern Atlantic Subtropical Gyre, suggesting that persistent contaminants may accumulate in ocean gyres. The median ΣPFAA surface concentration in the Northern Hemisphere (n = 17) was 105 pg L^-1, while for the Southern Hemisphere (n = 11) it was 28 pg L^-1. Generally, PFAA concentrations decreased with increasing distance to the coast and increasing depth. The C6-C9 PFCAs and C6 and C8 PFSAs dominated in surface waters, while longer-chain PFAAs (C10-C11 PFCAs) peaked at intermediate depths (500-1500 m). This profile may be explained by stronger sedimentation of longer-chain PFAAs, as they sorb more strongly to particulate organic matter.

1 H-Nuclear Magnetic Resonance Metabolomics Analysis of Arabidopsis thaliana Exposed to Perfluorooctanoic Acid and Perfluoroctanesulfonic Acid

Perfluorinated alkyl substances (PFAS) are ubiquitous environmental contaminants that are widely used in consumer products and fire suppression foams. The presence of PFAS in ground and surface water can create a route for PFAS to enter the soil, exposing ecosystems (including agroecosystems), where they will move through the food web via biomagnification. The toxicity of PFAS to plants, particularly in agricultural ecosystems, is of emerging concern due to the application of biosolids that are often contaminated with PFAS. Nevertheless, due to the low concentrations of PFAS in most agricultural soils, the direct impact of PFAS on plant health is not well understood. We used ¹ H-nuclear magnetic resonance (NMR) metabolomics to explore the effects of exposure of two key PFAS, perfluorooctanoic acid and perfluorooctanesulfonic acid, on Arabidopsis thaliana, a model organism. We found that Arabidopsis exhibited an accumulation of multiple metabolites, including soluble sugars (glucose and sucrose), multiple amino acids, and tri-carboxylic acid (TCA) cycle intermediates, suggesting that PFAS exposure impacts the metabolism of plants by causing an accumulation of stress-related amino acids and soluble sugars that drives increased activity of the TCA cycle. The present study shows that ¹ H-NMR metabolomics is a viable tool for investigating changes in the metabolic profile of plants exposed to PFAS and can be used to illuminate the stress response of plants in a high-throughput, nonbiased manner. Environ Toxicol Chem 2023;42:663-672. © 2022 SETAC.

A new on-line SPE LC-HRMS method for simultaneous analysis of selected emerging contaminants in surface waters

In recent years emerging contaminants (ECs) have received significant attention due to their widespread detection in surface waters and concerns that these compounds can cause adverse ecological and/or human health effects. Therefore, accurate methods for determining and quantifying ECs in surface water are essential for estimating their environmental impact. This work describes the development, validation and application of a sensitive multiclass method for simultaneous determination of 22 per and polyfluorinated alkyl substances (PFASs), 3 pharmaceuticals, 15 pesticides, and 2 bisphenols in surface water using on-line solid phase extraction (SPE) coupled with ultra-performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS). The method allows simultaneous sample clean-up from interfering matrices and lower limits of detection (LODs) by injecting a large sample volume into the LC system without compromising chromatographic efficiency and resolution. Linearity of response over several orders of magnitude was demonstrated for all tested compounds (R2 > 0.99), with the LODs ranging from 0.8 and 33.7 pg mL-1, allowing detection of ECs at trace levels in surface water. The method showed acceptable accuracy and precision (CV, % and RE below 20%) for all tested ECs. It also provided recoveries between 60% and 130% for all tested ECs. The validated method was successfully applied for analysis of surface water samples from three rivers (Cam, Ouse and Thames) in England. Several ECs, including perfluorooctanesulfonic acid (PFOS), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonic acid (PFHxS), dimethyl-metatoluamide (DEET) and ibuprofen were observed in analysed surface water above the method's limit of quantitation (LOQ), with concentrations ranging between 3.5 and 460 pg mL-1.

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.

Levels, distributions, and sources of legacy and novel per- and perfluoroalkyl substances (PFAS) in the topsoil of Tianjin, China

Soil is a major sink for per- and perfluoroalkyl substances (PFAS), wherein PFAS may be transferred through the food chain to predators at upper trophic levels, which poses a threat to human health. Herein, the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated. Seventeen PFAS congeners were identified, with concentrations ranging from 0.21 ng/g to 5.35 ng/g, with a mean concentration of 1.25 ng/g. The main PFAS in the topsoil was perfluorooctanoic acid (PFOA). 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA; <MDL-1.95 ng/g, mean 0.11 ng/g), as an emerging substitute for perfluorooctane sulfonate (PFOS), was also detected in the topsoil. It showed slightly higher concentrations than PFOS (<MDL-1.62 ng/g, mean 0.10 ng/g), indicating it has gradually replaced legacy PFOS in this area. Based on the positive-definite matrix factor (PMF) receptor model, the major PFAS sources was dominated by textile treatment, metal electroplating plants, and some potential precursors of PFAS with longer chains (>C8) were the major sources (43.4%), followed by food packaging as well as coating materials (25.5%). In addition, Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.

Prenatal exposure to persistent organic pollutants and metals and problematic child behavior at 3-5 years of age: a Greenlandic cohort study

High levels of persistent organic pollutants (POPs) and heavy metals are found in Arctic populations. POP and heavy metals are linked to impaired cognitive development. This study examined associations between prenatal POP and metals exposure and problematic child behavior using the Strength and Difficulties Questionnaire (SDQ). POPs and metals were measured in 102 pregnant Greenlandic women. During follow-up at 3–5 years, parents answered an assisted questionnaire including children’s SDQ scores. Associations were analyzed using linear and logistic regression analyses and adjusted for maternal plasma cotinine, educational level and age at delivery. In the adjusted analyses, the medium tertile of hexachlorobenzene (β = 3.06, p = 0.010), β-hexachlorocyclohexane (β = 3.58, p = 0.004) and trans-nonachlor (β = 2.06, p = 0.082) were positively associated with SDQ scores. The continuous cis-nonachlor (OR = 1.09, p = 0.079), dichloro-diphenyl-dichloroethylene (OR = 1.01, p = 0.077), trans-nonachlor (OR = 1.01, p = 0.091), and sum Organochlorine-Pesticides (OR = 1.00, p = 0.094) were positively associated with abnormal SDQ score and the continuous mirex (OR = 1.28, p = 0.096), oxychlordane (OR = 1.04, p = 0.066), and trans-nonachlor (OR = 1.02, p = 0.071) with abnormal hyperactivity score. We found no consistent evidence of associations between polychlorinated biphenyls, perfluoroalkylated substances and heavy metals and problematic behavior. Prenatal organochlorine pesticide exposure associated significantly with problematic behavior in 3–5 year old children.

Time trends of perfluoroalkyl substances in blood in 30-year old Norwegian men and women in the period 1986-2007

Biomonitoring studies are helpful tools and can increase our knowledge on time trends in human blood concentrations of PFASs: how they relate to emission trends and the potential prenatal exposure for future generations. In this study, serum was sampled in cross-sections of men and women who were 30 years old in each of the years 1986, 1994, 2001, and 2007 in Northern Norway and analyzed for 23 PFASs. Differences in serum concentrations across sampling years were investigated graphically and with significance testing and compared with those observed in our previous longitudinal study using repeated individual measurements in older men in the same years. The results demonstrate overall increasing blood burdens of PFASs in men and women in reproductively active ages during 1986-2001 and decreases until 2007. However, longer chained PFASs were still increasing in 2007 indicating divergent time trends between the different PFASs, underlining the importance of continued biomonitoring. Comparisons between 30-year-old men and older men within the same population demonstrated variation in time trends in the exact same years, underlining that biomonitoring studies must regard historic exposures and birth cohort effects.

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

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

Persistent Organic Pollutants (POPs) and Related Chemicals in the Global Environment: Some Personal Reflections

Persistent organic pollutants (POPs) and related chemicals are fascinating because of their combination of physical-chemical properties and complex effects. Most are man-made, but some also have natural origins. They are persistent in the environment, but they can be broken down variously by biodegradation, atmospheric reactions, and abiotic transformations. They can exist in the gas or particle phases, or both, in the atmosphere and in the dissolved or particulate phases, or both, in water. These combinations mean that they may undergo long-range transport in the atmosphere or oceans, or they may stay close to sources. Hence, emissions from one country are frequently a source of contamination to another country. They are also usually lipophilic, so-combined with persistence-this means they can accumulate in organisms and biomagnify through food chains. We all have a baseline of POPs residues in our tissues, even the unborn fetus via placental transfer and the newly born baby via mother's milk. POPs in biological systems occur in mixtures, so confirming effects caused by POPs on humans and other top predators is never straightforward. Depending on which papers you read, POPs may be relatively benign, or they could be responsible for key subchronic and chronic effects on reproductive potential, on immune response, as carcinogens, and on a range of behavioral and cognitive end points. They could be a factor behind diseases and conditions which have been increasingly reported and studied in modern societies. In short, they are endlessly fascinating to scientists and a nightmare to regulators and policy makers.

Impact of kidney hyperfiltration on concentrations of selected perfluoroalkyl acids among US adults for various disease groups

Data from the National Health and Nutrition Examination Survey (N = 6141) for the years 2003-2016 for US adults were analyzed to evaluate the impact of glomerular hyperfiltration on the observed concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid, perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) for several disease groups. Hyperfiltrators were defined as having an estimated glomerular filtration rate (eGFR) ≥ 110 mL/min/1.73 m², and normal filtrators were defined as those having an eGFR between 90 and 110 mL/min/1.73 m². The seven disease groups for which the data were analyzed were as follows: those (i) without any diseases; (ii) with hypertension only; (iii) with albuminuria only; (iv) with anemia only; (v) with diabetes only; (vi) with hypertension and one or more of diabetes, anemia, and albuminuria; and (vii) with two or more of diabetes, anemia, and albuminuria without hypertension. For almost every PFAA, for all seven disease groups except the albuminuria only group, hyperfiltrators had lower adjusted geometric means (AGM) than normal filtrators. For example, for the disease group with hypertension only, for PFOS, the AGMs for hyperfiltrators and normal filtrators were 8.3 and 10.6 ng/mL, respectively, for the total population. For the group with albuminuria only, normal filtrators were found to have higher AGMs than hyperfiltrators for the total population and males. For example, for PFHxS, the AGMs for normal and hyperfiltrators were 0.98 and 1.05 ng/mL, respectively, for the total population. For females, these AGMs for normal and hyperfiltrators were 0.96 and 0.86 ng/mL respectively. Males usually had higher AGMs than females, but the reverse was also true occasionally. Usually, male-female differences were substantially narrower for normal filtrators than hyperfiltrators. Irrespective of the filtration status, the disease group with hypertension only had the highest AGMs for every PFAA. AGMs for the anemia only group were the lowest for every PFAA as compared with other disease groups among hyperfiltrators.

PFOS dominates PFAS composition in ambient fine particulate matter (PM2.5) collected across North Carolina nearly 20 years after the end of its US production

Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) emitted from manufacturing plants, fire-fighting foams, and urban waste streams has received considerable attention due to concerns over toxicity and environmental persistence; however, PFASs in ambient air remain poorly understood, especially in the United States (US). We measured PFAS concentrations in ambient fine particulate matter (PM_2.5) at 5 locations across North Carolina over a 1 year period in 2019. Thirty-four PFASs, including perfluoroalkyl carboxylic, perfluoroalkane sulfonic, perfluoroalkyl ether carboxylic and sulfonic acids were analyzed by UHPLC/ESI-MS/MS. Quarterly averaged concentrations ranged from <0.004-14.1 pg m^-3. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) ranged from <0.18 to 14.1 pg m^-3, comparable to previous PM_2.5 measurements from Canada and Europe (<0.02-3.5 pg m^-3). Concentrations above 1 pg m^-3 were observed in July-September at Charlotte (14.1 pg m^-3, PFOA), Wilmington (4.75 pg m^-3, PFOS), and Research Triangle Park (1.37 pg m^-3, PFOS). Notably, PM_2.5 has a short atmospheric lifetime (<2 weeks), and thus, the presence of PFOS in these samples raises questions about their sources, since PFOS production was phased out in the US ∼20 years ago. This is the first US study to provide insights into ambient PFAS concentrations in PM_2.5.

Isolating the AFFF Signature in Coastal Watersheds Using Oxidizable PFAS Precursors and Unexplained Organofluorine

Water supplies for millions of U.S. individuals exceed maximum contaminant levels for per- and polyfluoroalkyl substances (PFAS). Contemporary and legacy use of aqueous film forming foams (AFFF) is a major contamination source. However, diverse PFAS sources are present within watersheds, making it difficult to isolate their predominant origins. Here we examine PFAS source signatures among six adjacent coastal watersheds on Cape Cod, MA, U.S.A. using multivariate clustering techniques. A distinct signature of AFFF contamination enriched in precursors with six perfluorinated carbons (C6) was identified in watersheds with an AFFF source, while others were enriched in C4 precursors. Principal component analysis of PFAS composition in impacted watersheds showed a decline in precursor composition relative to AFFF stocks and a corresponding increase in terminal perfluoroalkyl sulfonates with < C6 but not those with ≥ C6. Prior work shows that in AFFF stocks, all extractable organofluorine (EOF) can be explained by targeted PFAS and precursors inferred using Bayesian inference on the total oxidizable precursor assay. Using the same techniques for the first time in impacted watersheds, we find that only 24%-63% of the EOF can be explained by targeted PFAS and oxidizable precursors. Our work thus indicates the presence of large non-AFFF organofluorine sources in these coastal watersheds.

Time Trend of Persistent Organic Pollutants and Metals in Greenlandic Inuit during 1994-2015

Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), organchlorine pesticides and perfluoroalkylated substances (PFASs) and heavy metals bioaccumulate in the marine food chain in the Arctic regions, and thus, the Greenlandic population has a higher body burden due to relatively high intake of marine mammals. We assessed the temporal trend for POPs, including PCB 153; 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE); oxychlordane; six PFASs; mercury; lead and selenium in Inuit from Ilulissat, Nuuk, and across Greenland (including thirteen towns/districts), from 1994 to 2015. Data showed a significant annual decrease of 6.85-8.61% for PCB153, 6.67-8.61% for p,p'-DDE, 6.11-9.52% for oxychlordane, 5.92-6.76% for mercury and 6.48-9.43% for lead in Inuit women from Nuuk, Ilulissat, and across thirteen Greenlandic districts. The blood selenium level of all Greenlandic women increased 1.01% annually, while the trend direction was negative for Nuuk women. A similar pattern was seen for men across Greenland, with a yearly decrease of 11.3% for PCB 153, 8.61% for p,p'-DDE, 15.6% for oxychlordane, 13.1% for mercury and 12.2% for lead. Perfluorooctane sulfonate, perfluorohexane sulfonate and perfluorooctanoic acid significantly decreased 5.82-11.7% annually for both women and men across Greenland. For perfluorononanoic acid, perfluorodecanoic acid and perfluoroundecanoic acid, we observed an increasing trend for women across Greenland. In conclusion, there was a decreasing trend of the regulated POPs and metals but a potential increasing trend of the nonregulated PFASs in the Greenlandic population between 1994 and 2015. The continuing biomonitoring of contaminants of concern is important to protect the Arctic population heath.

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.

Endocrine Disruptor Potential of Short- and Long-Chain Perfluoroalkyl Substances (PFASs)-A Synthesis of Current Knowledge with Proposal of Molecular Mechanism

Endocrine disruptors are a group of chemical compounds that, even in low concentrations, cause a hormonal imbalance in the body, contributing to the development of various harmful health disorders. Many industry compounds, due to their important commercial value and numerous applications, are produced on a global scale, while the mechanism of their endocrine action has not been fully understood. In recent years, per- and polyfluoroalkyl substances (PFASs) have gained the interest of major international health organizations, and thus more and more studies have been aimed to explain the toxicity of these compounds. PFASs were firstly synthesized in the 1950s and broadly used in the industry in the production of firefighting agents, cosmetics and herbicides. The numerous industrial applications of PFASs, combined with the exceptionally long half-life of these substances in the human body and extreme environmental persistence, result in a common and chronic exposure of the general population to their action. Available data have suggested that human exposure to PFASs can occur during different stages of development and may cause short- or/and long-term health effects. This paper synthetizes the current literature reports on the presence, bioaccumulation and, particularly, endocrine toxicity of selected long- and short-chain PFASs, with a special emphasis on the mechanisms underlying their endocrine actions.

Understanding PFAAs exposure in a generalist seabird species breeding in the vicinity of a fluorochemical plant: Influence of maternal transfer and diet

Perfluoroalkyl acids (PFAAs) are a focus of scientific and regulatory attention nowadays. However, PFAAs dynamics in the environment and the factors that determine wildlife exposure are still not well understood. In this study we examined PFAAs exposure in chicks of a generalist seabird species, the lesser black-backed gull (Larus fuscus), breeding 49 km away of a PFAAs hotspot (a fluorochemical plant in Antwerp, Belgium). In order to study the pathways of PFAAs exposure, we measured how chicks' PFAAs burden varied with age, sex, and body condition. In addition, we related PFAA concentrations to chicks' diet using stable isotope signatures. For this purpose, we studied plasma PFAA concentrations in 1-week and 4-week-old gull chicks. Only 4 (PFOS, PFOA, PFDA and PFNA) out of the 13 target PFAA compounds were detected. Measured concentrations of PFOS and PFOA were generally high compared to other seabird species but were highly variable between individuals. Furthermore, our results suggest that maternal transfer plays a significant role in determining chicks' PFAAs burden, and that there are variable sources of exposure for PFOS and PFOA during post-hatching development. The association between PFOS and specific stable isotopes (i.e. δ¹⁵N and δ¹³C) suggests a higher exposure to PFOS in birds with a predominantly marine diet. We also found that males' condition was positively associated with PFOS plasmatic concentration, probably due to the indirect effect of being fed a high quality (marine) diet which appears PFOS rich. Yet, exact exposure source(s) for PFOA remain(s) unclear. Given that PFOS concentrations measured in some chicks surpassed the toxicity reference value calculated for top avian predators, continued monitoring of exposure and health of this gull population, and other wildlife populations inhabiting the area, is highly recommended.

Paper product production identified as the main source of per- and polyfluoroalkyl substances (PFAS) in a Norwegian lake: Source and historic emission tracking

The entirety of the sediment bed in lake Tyrifjorden, Norway, is contaminated by per- and polyfluoroalkyl substances (PFAS). A factory producing paper products and a fire station were investigated as possible sources. Fire station emissions were dominated by the eight carbon perfluoroalkyl sulfonic acid (PFSA), perfluorooctanesulfonic acid (PFOS), from aqueous film forming foams. Factory emissions contained PFOS, PFOS precursors (preFOS and SAmPAP), long chained fluorotelomer sulfonates (FTS), and perfluoroalkyl carboxylic acids (PFCA). Concentrations and profiles in sediments and biota indicated that emissions originating from the factory were the main source of pollution in the lake, while no clear indication of fire station emissions was found. Ratios of linear-to branched-PFOS increased with distance from the factory, indicating that isomer profiles can be used to trace a point source. A dated sediment core contained higher concentrations in older sediments and indicated that two different PFAS products have been used at the factory, referred to here as Scotchban and FTS mixture. Modelling, based on the sediment concentrations, indicated that 42-189 tons Scotchban, and 2.4-15.6 tons FTS mixture, were emitted. Production of paper products may be a major PFAS point source, that has generally been overlooked. It is hypothesized that paper fibres released from such facilities are important vectors for PFAS transport in the aquatic environment.

Stranded cetaceans warn of high perfluoroalkyl substance pollution in the western Mediterranean Sea

Perfluoroalkyl substances (PFASs) are a class of organohalogenated compounds of environmental concern due to similar characteristics as the well-studied legacy persistent organic pollutants (POPs) that typically show environmental persistence, biomagnification and toxicity. Nevertheless, PFAS are still poorly regulated internationally and in many aspects poorly understood. Here, we studied liver and muscle concentrations in five cetacean species stranded at the southeastern coast of Spain during 2009-2018. Twelve of the fifteen targeted compounds were detected in >50% of the liver samples. Hepatic concentrations were significantly higher than those in muscle reflecting the particular toxicokinetics of these compounds. Bottlenose dolphins Tursiops truncatus showed the highest hepatic ΣPFAS (n = 5; 796.8 ± 709.0 ng g^-1 ww) concentrations, followed by striped dolphin Stenella coeruleoalba (n = 29; 259.5 ± 136.2 ng g^-1 ww), sperm whale Physeter macrocephalus (n = 1; 252.8 ng g^-1 ww), short-beaked common dolphin Delphinus delphis (n = 2; 240.3 ± 218.6 ng g^-1 ww) and Risso's dolphin Grampus griseus (n = 1; 78.7 ng g^-1 ww). These interspecies differences could be partially explained by habitat preferences, although they could generally not be related to trophic position or food chain proxied by stable N (δ¹⁵N) and C (δ¹³C) isotope values, respectively. PFAS profiles in all species showed a similar pattern of concentration prevalence in the order PFOS>PFOSA>PFNA≈PFFUnA>PFDA. The higher number of samples available for striped dolphin allowed for evaluating their PFAS burden and profile in relation to the stranding year, stable isotope values, and biological variables including sex and length. However, we could only find links between δ¹⁵N and PFAS burdens in muscle tissue, and between stranding year and PFAS profile composition. Despite reductions in the manufacturing industry, these compounds still appear in high concentrations compared to more than two decades ago in the Mediterranean Sea and PFOS remains the dominating compound.

Exposure characteristics for congeners, isomers, and enantiomers of perfluoroalkyl substances in mothers and infants

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in the environment, making it inevitable for humans to be exposed to these pollutants. The exposure begins while in utero and continues in infancy, during the potentially most sensitive early stages of life. This review summarizes the current knowledge on pre- and neo-natal exposures based on more than 200 articles published from 2000 to date. All relevant biological matrices used in the cited studies were included, such as maternal blood, umbilical cord blood, breast milk, placenta, amniotic fluid, fetal organs, newborns' dried blood spots, and infant serum. We show that such exposures are geographically global with significant discrepancies among countries and continents, and that while the levels of major legacy PFASs (PFOS and PFOA) have declined since 2000, those of others may have not. We also show that levels of PFOS and PFOA exceed those of some major environmental toxins, such as p,p'-DDE, BDE-47, PCB-153, PBB-153, and OH-PBDEs in maternal blood. Given that the behavior and potential effects have an origin in molecular structure, biomonitoring and research at the levels of isomers and enantiomers are critically important. Through critical analysis of these works, we summarize the major achievements, consensus, and the deficiencies of existing research. To our knowledge, this is the first review on the overall internal exposure status of mothers and infants to PFASs during pregnancy and lactation.

Legacy and Novel Per- and Polyfluoroalkyl Substances in Juvenile Seabirds from the U.S. Atlantic Coast

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic, globally distributed chemicals. Legacy PFAS, including perfluorooctane sulfonate (PFOS), have been regularly detected in marine fauna but little is known about their current levels or the presence of novel PFAS in seabirds. We measured 36 emerging and legacy PFAS in livers from 31 juvenile seabirds from Massachusetts Bay, Narragansett Bay, and the Cape Fear River Estuary (CFRE), United States. PFOS was the major legacy perfluoroalkyl acid present, making up 58% of concentrations observed across all habitats (range: 11-280 ng/g). Novel PFAS were confirmed in chicks hatched downstream of a fluoropolymer production site in the CFRE: a perfluorinated ether sulfonic acid (Nafion byproduct 2; range: 1-110 ng/g) and two perfluorinated ether carboxylic acids (PFO4DA and PFO5DoDA; PFO5DoDA range: 5-30 ng/g). PFOS was inversely associated with phospholipid content in livers from CFRE and Massachusetts Bay individuals, while δ 13C, an indicator of marine versus terrestrial foraging, was positively correlated with some long-chain PFAS in CFRE chick livers. There is also an indication that seabird phospholipid dynamics are negatively impacted by PFAS, which should be further explored given the importance of lipids for seabirds.

Fluorinated Precursor Compounds in Sediments as a Source of Perfluorinated Alkyl Acids (PFAA) to Biota

The environmental behavior of perfluorinated alkyl acids (PFAA) and their precursors was investigated in lake Tyrifjorden, downstream a factory producing paper products coated with per- and polyfluorinated alkyl substances (PFAS). Low water concentrations (max 0.18 ng L^-1 linear perfluorooctanesulfonic acid, L-PFOS) compared to biota (mean 149 μg kg^-1 L-PFOS in perch livers) resulted in high bioaccumulation factors (L-PFOS BAF_Perch liver: 8.05 × 10⁵-5.14 × 10⁶). Sediment concentrations were high, particularly for the PFOS precursor SAmPAP diester (max 1 872 μg kg^-1). Biota-sediment accumulation factors (L-PFOS BSAF_Perch liver: 22-559) were comparable to elsewhere, and concentrations of PFAA precursors and long chained PFAA in biota were positively correlated to the ratio of carbon isotopes (¹³C/¹²C), indicating positive correlations to dietary intake of benthic organisms. The sum fluorine from targeted analyses accounted for 54% of the extractable organic fluorine in sediment, and 9-108% in biota. This, and high trophic magnification factors (TMF, 3.7-9.3 for L-PFOS), suggests that hydrophobic precursors in sediments undergo transformation and are a main source of PFAA accumulation in top predator fish. Due to the combination of water exchange and dilution, transformation of larger hydrophobic precursors in sediments can be a source to PFAA, some of which are normally associated with uptake from water.

Perfluoroalkyl substances (PFASs) in white whales (Delphinapterus leucas) from Svalbard - A comparison of concentrations in plasma sampled 15 years apart

The objective of the present study was to investigate recent concentrations of perfluoroalkyl substances (PFASs) in white whales (Delphinapterus leucas) from Svalbard and compare them to concentrations found in white whales sampled from that same area 15 years ago. Plasma collected from live-captured white whales from two time periods (2013-2014, n = 9, and 1996-2001, n = 11) were analysed for 19 different PFASs. The 11 PFASs detected included seven C₈-C₁₄ perfluoroalkyl carboxylates (PFCAs) and three C₆-C₈ perfluoroalkyl sulfonates (PFSAs) as well as perfluorooctane sulfonamide (FOSA). Recent plasma concentrations (2013-2014) of the dominant PFAS in white whales, perfluorooctane sulfonate (PFOS; geometric mean = 22.8 ng/mL), was close to an order of magnitude lower than reported in polar bears (Ursus maritimus) from Svalbard. PFOS concentrations in white whales were about half the concentrations in harbour (Phoca vitulina) and ringed (Pusa hispida) seals, similar to hooded seals (Cystophora cristata) and higher than in walruses (Odobenus rosmarus) from that same area. From 1996 to 2001 to 2013-2014, plasma concentrations of PFOS decreased by 44%, whereas four C_9-12 PFCAs and total PFCAs increased by 35-141%. These results follow a similar trend to what has been reported in other studies of Arctic marine mammals from Svalbard. The most dramatic change has been the decline of PFOS concentrations since 2000, corresponding to the production phase-out of PFOS and related compounds in many countries around the year 2000 and a global restriction on these substances in 2009. Still, the continued dominance of PFOS in white whales, and increasing concentration trends for several PFCAs, even though exposure is relatively low, calls for continued monitoring of concentrations of both PFCAs and PFSAs and investigation of biological effects.

Will Climate Change Influence Production and Environmental Pathways of Halogenated Natural Products?

Thousands of halogenated natural products (HNPs) pervade the terrestrial and marine environment. HNPs are generated by biotic and abiotic processes and range in complexity from low molecular mass natural halocarbons (nHCs, mostly halomethanes and haloethanes) to compounds of higher molecular mass which often contain oxygen and/or nitrogen atoms in addition to halogens (hHNPs). nHCs have a key role in regulating tropospheric and stratospheric ozone, while some hHNPs bioaccumulate and have toxic properties similar those of anthropogenic-persistent organic pollutants (POPs). Both chemical classes have common sources: biosynthesis by marine bacteria, phytoplankton, macroalgae, and some invertebrate animals, and both may be similarly impacted by alteration of production and transport pathways in a changing climate. The nHCs scientific community is advanced in investigating sources, atmospheric and oceanic transport, and forecasting climate change impacts through modeling. By contrast, these activities are nascent or nonexistent for hHNPs. The goals of this paper are to (1) review production, sources, distribution, and transport pathways of nHCs and hHNPs through water and air, pointing out areas of commonality, (2) by analogy to nHCs, argue that climate change may alter these factors for hHNPs, and (3) suggest steps to improve linkage between nHCs and hHNPs science to better understand and predict climate change impacts.

Toxic effect of perfluorooctane sulfonate on plants in vertical-flow constructed wetlands

Per-and polyfluoroalkyl substances (PFASs) can be taken up and bioaccumulated in plants, but the toxic mechanisms of PFASs on wetland plants are still unclear. In present study, the toxic influences of perfluorooctane sulfonate (PFOS) on Eichhornia crassipes (E. crassipes) and Cyperus alternifolius (C. alternifolius) in a vertical-subsurface-flow constructed wetland were evaluated. The results showed that E. crassipes was more tolerant to PFOS stress than C. alternifolius, and the growth and chlorophyll synthesis of the two plants were promoted by low concentration (<0.1 mg/L) of PFOS, and the chlorophyll synthesis was inhibited by high concentration (10 mg/L) of PFOS but the growth did not change obviously. The catalase activity and malondialdehyde content in the leaves of the two plants increased, peroxidase activity decreased under exposure to high concentrations of PFOS, and superoxide dismutase activity did not change. Under PFOS stress, the membrane of plant leaves and the cell structure of the two wetland plants were destroyed, and the mitochondrial contour of root cells became incomplete. Tanscriptomic analysis showed that the expression levels of genes related to cell wall formation, the cell apoptosis pathway, material synthesis, and metabolism in the plants were changed by PFOS. Analysis in fluorogenic quantitative real time polymerase chain reaction (RT-qPCR) also confirmed that the photosynthesis system of E. crassipes was inhibited, while that of C. alternifolius was promoted.

Perfluoroalkyl substances in sediments from the Bering Sea to the western Arctic: Source and pathway analysis

Although perfluoroalkyl substances (PFASs) are ubiquitous in the Arctic, their dominant pathways to the Arctic remain unclear. Most modeling studies support major oceanic transport for PFASs in the Arctic seawater, but this conclusion contradicts the rapid response of PFASs to global emissions in some biota species. Sediments, which act as important PFAS sinks for seawater and potential PFAS source to the benthic food web, are important for interpreting the fate of PFASs in the Arctic. Here we investigate the occurrence of 9 PFASs in one core (1945-2014) and 29 surface sediments from the Bering Sea to the western Arctic. Total PFAS concentrations (0.06-1.73 ng/g dw) in surface sediments were dominated by perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluorobutyl sulfonate (PFBS), with higher levels in the Bering Sea slope and the northeast Chukchi Sea. Historical trends in PFASs varied among individuals, with PFOS declining in the early 2000s while PFNA showing an increasing up-core trend. Analysis of positive matrix factorization model identified that the major PFAS sources in the sediment core were dominated by the atmospheric oxidation of consumer use of PFOS precursor-based products (45.0%), while the oceanic transport of fluoropolymer manufacture of polyvinylidene fluoride (mainly PFNA) exhibited an increasing trend over time, becoming dominant in surface sediments (42.8%). Besides, local input of possible aqueous fire-fighting foams (mainly PFOS and PFBS) also acted as an important source currently (30.1%) and historically (34.9%). Our study revealed that the pathways of PFASs in Arctic sediments varied greatly for individuals and the conclusion of PFOS originating from mainly atmospheric oxidation was different from seawater modeling results. This, together with the high possibility of sediments as direct source to Arctic food web (supported by similar PFAS compositions and temporal variations), help provide additional evidence regarding PFAS pathways to the Arctic.

Property Estimation of Per- and Polyfluoroalkyl Substances: A Comparative Assessment of Estimation Methods

To accurately predict the environmental fate of per- and polyfluoroalkyl substances (PFAS), high-quality physicochemical property data are required. Because such data are often not available from experiments, assessment of the accuracy of existing property estimation models is essential. The quality of predicted physicochemical property data for a set of 25 PFAS was examined using COSMOtherm, EPI Suite, the estimation models accessible through the US Environmental Protection Agency's CompTox Chemicals Dashboard, and Linear Solvation Energy Relationships (LSERs) available through the UFZ-LSER Database. The results showed that COSMOtherm made the most accurate acid dissociation constant and air-water partition ratio estimates compared with literature data. The OPEn structure-activity/property Relationship App (OPERA; developed through the CompTox Chemicals Dashboard) estimates of vapor pressure and dry octanol-air partition ratios were the most accurate compared with other models of interest. Wet octanol-water partition ratios were comparably predicted by OPERA and EPI Suite, and the organic carbon soil coefficient and solubility were well predicted by OPERA and COSMOtherm. Acid dissociation of the perfluoroalkyl acids has a significant impact on their physicochemical properties, and corrections for ionization were included where applicable. Environ Toxicol Chem 2020;39:775-786. © 2020 SETAC.

Poly- and Perfluoroalkyl Substances in Seawater and Plankton from the Northwestern Atlantic Margin

The ocean is thought to be the terminal sink for poly- and perfluoroalkyl substances (PFAS) that have been produced and released in large quantities for more than 60 years. Regulatory actions have curbed production of legacy compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), but impacts of regulations on PFAS releases to the marine environment are poorly understood. Here, we report new data for 21 targeted PFAS in seawater and plankton from the coast, shelf, and slope of the Northwestern Atlantic Ocean. We find strong inverse correlations between salinity and concentrations of most PFAS, indicating that ongoing continental discharges are the major source to the marine environment. For legacy PFAS such as PFOS and PFOA, a comparison of inland and offshore measurements from the same year (2014) suggests that there are ongoing releases to the marine environment from sources such as submarine groundwater discharges. Vertical transport of most PFAS associated with settling particles from the surface (10 m) to deeper waters is small compared to advective transport except for perfluorodecanoic acid (PFDA; 35% of vertical flux) and precursor compounds to PFOS (up to 86%). We find higher than expected bioaccumulation factors (BAFs = Cplankton/Cwater) for perfluorinated carboxylic acids (PFCAs) with five and six carbons (log BAF = 2.9-3.4) and linear PFOS (log BAF = 2.6-4.3) in marine plankton compared to PFCAs with 7-11 carbons. We postulate that this reflects additional contributions from precursor compounds. Known precursor compounds detected here have among the highest BAFs (log BAF > 3.0) for all PFAS in this study, suggesting that additional research on the bioaccumulation potential of unknown organofluorine compounds is urgently needed.

Bioaccumulation and biomagnification of perfluoroalkyl acids and precursors in East Greenland polar bears and their ringed seal prey

The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean Σ₄PFSA (perfluoroalkyl sulfonic acid) concentration (C₄, C₆, C₈ and C₁₀) was 2611 ± 202 ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20 ± 3 ng/g ww (89% PFOS) concentration in fat. The mean Σ₄PFSAs in seal liver was 111 ± 5 ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05 ± 0.01 ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10 ± 1.4 ng/g ww) and seal (mean 0.6 ± 0.1 ng/g ww) liver but not in fat or blubber. The mean Σ₁₃PFCAs (C₄-C₁₈; perfluoroalkyl carboxylic acids) in bear liver (924 ± 71 ng/g ww) was much greater than in seal liver (74 ± 6 ng/g ww). In bear fat and seal blubber, the mean Σ₁₃PFCAs were 15 ± 1.9 and 0.9 ± 0.1 ng/g ww, respectively. Longer chain C₁₁ to C₁₄ PFCAs dominated in bear fat and seal blubber (60-80% of Σ₁₃PFCA), whereas shorter-chain C₉ to C₁₁ PFCAs dominated in the liver (85-90% of Σ₁₃PFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C₉ to C₁₃ PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C₉ to C₁₃) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals.

The PFOS disturbed immunomodulatory functions via nuclear Factor-κB signaling in liver of zebrafish (Danio rerio)

Excessive perfluorooctane sulfonate (PFOS) in natural water ecosystem has the potential to detrimentally affect immune system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of PFOS on growth performance, organizational microstructure, activities of immune-related enzymes and expressions of immune-related genes in male zebrafish (Danio rerio) exposed to different concentrations of 0, 0.02, 0.04 and 0.08 mg/L of PFOS for 7, 14, and 21 days or cotreatment with PFOS and PDTC to investigate the effects of PFOS on immune system and the potential toxic mechanisms caused by PFOS. The results indicated that PFOS accumulated in livers after exposure, and remarkably elevations were found in three exposure groups compared with the control group at three stages. The growth of the adult zebrafish in the experiments was significantly inhibited, the microstructures of liver were serious damaged. The ROS levels were remarkably increased. The activities of ACP, AKP, and lysozyme were obviously decreased, while the activities of MPO and NF-κB were significantly increased. The expressions of immune-related mRNA were significantly affected. After co-treatment with PFOS and PDTC, the growth inhibition, the morphological damage, the ROS induction, and the expressions of immune-related mRNA were reversed. Taken together, the results indicated that PFOS can significantly inhibit the growth, disturb the immune system by changing the normal structure of liver, the activities of immune-related enzymes, and a series of gene transcriptions involved in immune regulation in liver of male zebrafish. PFOS-induced pro-inflammatory effect of hepatocytes was observed, and the involvement of NF-κB signaling pathway was participated in its action mechanism. These findings provide further evidence that PFOS interferes with the immune regulation of liver of male zebrafish under in vivo conditions.

Temporal trends and sediment-water partitioning of per- and polyfluoroalkyl substances (PFAS) in lake sediment

The use of per- and polyfluoroalkyl substances (PFAS) containing aqueous film forming foams (AFFF) at fire training facilities can have an adverse impact on the surrounding environment. The aim of the present study was to study the distribution and temporal trend of 26 PFAS in water and sediment cores for a lake and a pond affected by AFFF release from a fire training facility in Luleå, northern Sweden. In the aqueous phase, maximum ΣPFAS concentration was 1.700 ± 90 ng L^-1. Dominant PFAS groups were perfluoroalkane sulfonates (PFSAs) with 70% of the ΣPFAS, followed by perfluoroalkyl carboxylates (PFCAs, 29%), whereas the contribution of 6:2 fluorotelomer carboxylate (FTSAs) was low (<1%). In the sediment core samples, ΣPFAS concentrations ranged between <1 μg kg^-1 dry weight (dw) and 76 μg kg^-1 dw, where perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) had an average contribution of ∼71% and ∼23% of the ΣPFAS. The sediment core analysis indicated that the PFAS contamination began about 1994 and the highest accumulation rate was observed for the period 2003-2009. The PFAS flux increased from 2.3 μg m^-2 yr^-1 dw in 1994 to 12 μg m^-2 yr^-1 dw by 2009. Over the accumulation period 1994-2009, the lake sediment surface received 213 μg m^-2 dw for ƩPFAS, where PFOS contributed with 125 μg m^-2 yr^-1 dw and PFHxS with 65 μg m^-2 dw. Results point to that sediment cores collected near PFAS hotspot areas can be used as a contamination record to reconstruct release history.

A Review of Perfluoroalkyl Acids (PFAAs) in terms of Sources, Applications, Human Exposure, Dietary Intake, Toxicity, Legal Regulation, and Methods of Determination

Per- and polyfluoroalkyl substances (PFASs) are widely distributed across the world and are expected to be of concern to human health and the environment. The review focuses on perfluoroalkyl acids (PFAAs) and, in particular, on the most frequently discussed perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs). In this study, some basic information concerning PFASs is reviewed, focusing mainly on PFAAs (perfluoroalkyl acids). We have made efforts to systemize their division into groups according to chemical structure, describe their basic physicochemical properties, characterize production technologies, and determine potential human exposure routes with particular reference to oral exposure. A variety of possible toxicological effects to human health are also discussed. In response to increasing public concern about the toxicity of PFAAs, an evaluation of dietary intake has been undertaken for two of the most commonly known PFAAs: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). As summarized in this study, PFAAs levels need further assessment due to the science-based TWI standards laid down by the EFSA’s CONTAM Panel regarding the risk to human health posed by the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food (tolerable weekly intakes of PFOA and PFOS set up to 6 ng·kg−1·bw·week−1 and 13 ng·kg−1·bw·week−1, respectively). Current legislation, relevant legislation on PFAAs levels in food, and the most popular methods of analysis in food matrices are described.

Nitrogen-doped carbon dots as an effective fluorescence enhancing system for the determination of perfluorooctyl sulfonate

Nitrogen-doped carbon dots (NCDs) were synthesized via hydrothermal treatment of vitamin B1 and triethylamine. The NCDs exhibit strong blue fluorescence (with a peak at 437 nm at an excitation wavelength of 370 nm), good water solubility and excellent fluorescence stability in the pH 3~12 range, at ionic strengths between 0.01 and 1 M, and under UV illumination for 6 h, as well as incubation temperature of 15~60 °C. The nanoparticles respond selectively and sensitively to trace concentrations of perfluorooctane sulfonate (PFOS) through electrostatic interactions between PFOS and NCDs. This is accompanied by the aggregation of NCDs to yield enhanced fluorescence. The nanoprobe has high selectivity for PFOS even in presence of other common ions such as metal ions, anions, and structural analogues such as surfactants. Under the optimal conditions, the response is linear in the 0.3 to 160 nM PFOS concentration range with a detection limit of 0.3 nM. Satisfactory results were achieved for determination of PFOS in spiked real water samples. Graphical abstract Schematic presentation of the synthetic route to nitrogen-doped carbon dots (NCDs) starting from vitamin B1 and triethylamine, and its application for selective and sensitive fluorometric determination of perfluorooctane sulfonate (PFOS).

Global transport of perfluoroalkyl acids via sea spray aerosol

Perfluoroalkyl acids (PFAAs) are persistent organic pollutants found throughout the world's oceans. Previous research suggests that long-range atmospheric transport of these substances may be substantial. However, it remains unclear what the main sources of PFAAs to the atmosphere are. We have used a laboratory sea spray chamber to study water-to-air transfer of 11 PFAAs via sea spray aerosol (SSA). We observed significant enrichment of all PFAAs relative to sodium in the SSA generated. The highest enrichment was observed in aerosols with aerodynamic diameter < 1.6 μm, which had aerosol PFAA concentrations up to ∼62 000 times higher than the PFAA water concentrations in the chamber. In surface microlayer samples collected from the sea spray chamber, the enrichment of the substances investigated was orders of magnitude smaller than the enrichment observed in the aerosols. In experiments with mixtures of structural isomers, a lower contribution of branched PFAA isomers was observed in the surface microlayer compared to the bulk water. However, no clear trend was observed in the comparison of structural isomers in SSA and bulk water. Using the measured enrichment factors of perfluorooctanoic acid and perfluorooctane sulfonic acid versus sodium we have estimated global annual emissions of these substances to the atmosphere via SSA as well as their global annual deposition to land areas. Our experiments suggest that SSA may currently be an important source of these substances to the atmosphere and, over certain areas, to terrestrial environments.

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.

Seasonal and annual variations in removal efficiency of perfluoroalkyl substances by different wastewater treatment processes

Municipal wastewater treatment plants (WWTPs) are important in the migration and transformation of perfluoroalkyl substances (PFASs) in water bodies. Six municipal WWTPs located in the upper reaches of the Guanting reservoir, along the Yanghe River, were sampled from November 2016 to July 2017. Influents, effluents, and activated sludge solutions were sampled and the concentrations of 17 PFASs were analyzed. Perfluorobutanoic acid (PFBA), Perfluorooctanoic acid (PFOA), Perfluorohexanoic acid (PFHxA), Perfluoropentanoic acid (PFPeA), Perfluorobutane sulfonat (PFBS) and Perfluorooctane sulfonate (PFOS) accounted for more than 90% of these. Seasonal variations in PFASs in influent directly influenced concentrations in supernatant and effluent. The annual average PFAS concentrations were 46.4, 45.1, and 38.5 ng L^-1 in influent, supernatant, and effluent, respectively, indicating that WWTPs do not efficiently remove PFASs from wastewater. Annual average PFAS removal efficiencies differed among WWTPs, were influenced primarily by the treatment process used at each, and followed the order Cyclic Activated Sludge System (CASS, 32.2%) > Orbal Oxidation Ditch (OD, 17.5%) > Anaeroxic-Anoxic-Oxic (A²/O, -1.49%). Short-chain PFASs were removed significantly more efficiently in the CASS compared to the other systems. These results can show how traditional wastewater treatment plants can help remove PFASs from the environment.

Emissions, Transport, and Fate of Emerging Per- and Polyfluoroalkyl Substances from One of the Major Fluoropolymer Manufacturing Facilities in China

Fluoropolymer manufacturing is a major historical source of perfluorooctanoic acid (PFOA) on a global scale, but little is known about the emissions, transport, and fate of emerging per- and polyfluoroalkyl substances (PFASs). Here, we performed a comprehensive spatial trend and interyear comparison of surface water and sediment samples from the Xiaoqing River, which receives water discharge from one of the major fluoropolymer manufacturing facilities in China. A suspect screening identified 42 chemical formulas, including the tetramer acid of hexafluoropropylene oxide (HFPO-TeA) and numerous tentatively detected isomers of C9-C14 per- or polyfluoroalkyl ether carboxylic acids (PFECAs). As revealed by the spatial trends and peak area-based sediment-water distribution coefficients, emerging PFASs with 3-9 perfluorinated carbons were transported unimpededly with the bulk water flow having no measurable degradation. Emerging PFASs with >9 perfluorinated carbons displayed more rapidly decreasing spatial trends than shorter-chain homologues in surface water due to increasing sedimentation rates. The presence of HFPO oligomers, monoether PFECAs, monohydrogen-substituted perfluoroalkyl carboxylic acids (PFCAs) and monochlorine-substituted PFCAs could partly be explained by the active use of polymerization aids or the impurities therein. However, further research is encouraged to better characterize the emissions of low-molecular-weight PFASs from fluoropolymers throughout their life-cycle.

Differential contribution of animal and vegetable food items on persistent organic pollutant serum concentrations in Spanish adults. Data from BIOAMBIENT.ES project

Diet is considered the main source of Persistent Organic Pollutant (POP) exposure in the general population, although there are still several gaps of knowledge regarding the differential contribution of main food groups. The aim of this study was to identify dietary patterns that contribute to human exposure to organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and Perfluoroalkyl Substances (PFASs). Study population (n=1880, 18-65years old) was recruited during 2009-2010 in all the main geographical areas of Spain. For this work, exposure was estimated by chemical analyses of serum levels of 6 PCBs (n=1880), 13 OCPs (n=934), and 6 (PFASs) in a subsample of 755 (n=755). Dietary habits and covariates were gathered via self-administered questionnaires. Data analyses were performed by means of multivariable linear regression and weighted quantile sum regression. Both the consumption of animal-based and plant-based food were positively associated with the individual concentrations of p,p´-DDE, hexachlorobenzene, and PCB-congeners -138, -153, and-180. The contribution of animal-based products was 2.1-4.0× stronger except in p,p´-DDE, to which both patterns had similar contributions. In PFASs only animal food was positively associated with the exposure levels. The main animal-based contributors to PCB exposure were fish (49-64%) and eggs (19-36%), while OCP concentrations were mainly influenced by dairy products (32-48%) and fish (47-48%). PFOA and PFHxS were mainly explained by cold-meat (34-37%), fish (25-26%), and eggs (19-21%), while PFOS and PFDA were primarily influenced by fish consumption (44-77%). In the case of plant-based items, fruits (25-82%) and vegetables (18-63%) accounted for the majority of the variability of PCB and OCP concentrations. Our results highlight the relevance of dietary POP exposure as well as the need for the consideration of nutritional interventions in public health programs aiming to reduce POP exposure in the general population.

Spatial variation in the atmospheric deposition of perfluoroalkyl acids: source elucidation through analysis of isomer patterns

To evaluate the relevance of different proposed sources of perfluoroalkyl acids (PFAAs) to air, their isomer patterns were analyzed in deposition samples collected from five geographical locations: two urban sites in China (>360 km from known operational fluorochemical manufacturing facilities), one remote marine site in the Azores archipelago and two Swedish sites representing urban and background conditions. Despite variable contributions from linear perfluorooctanoic acid (PFOA) in the samples, the pattern of branched PFOA isomers was similar to those of technical standards manufactured using electrochemical fluorination (ECF). This indicates that atmospheric fate processes have little influence on the isomer profiles of PFOA and that the relative contribution of PFOA manufactured using ECF (typically 20-26% branched isomers) and telomerization (typically one single linear isomer) can be determined in atmospheric deposition samples by analyzing the proportions of branched and linear isomers. In Chinese samples, branched isomers contributed 15-25% to the total loading of PFOA, indicating that the samples were dominated by ECF PFOA. Samples in the Azores had 8-10% contribution from branched PFOA isomers, indicating an approximately equal influence of ECF and telomer sources. Only three of the samples collected in Sweden displayed a quantifiable contribution from branched PFOA isomers (8-13% of overall PFOA loading in the samples). One branched PFNA isomer was observed in samples from the marine sites. Direct manufacturing discharges, transport of sea spray aerosols and degradation of precursors are all suggested to be contributing sources, albeit to different extents, to PFAAs in air at the different geographical locations where precipitation was sampled.