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N-ethyl perfluorooctane sulfonamide (EtFOSA) is the active ingredient of Sulfluramid, a pesticide which is used extensively in South America for control of leaf-cutting ants. Despite being a known precursor to perfluorooctanesulfonate (PFOS), the importance of EtFOSA as a source of environmental PFOS remains unclear. In the present work, uptake, leaching, and biodegradation of EtFOSA and its transformation products were assessed over 81 days in soil-carrot (Daucus carota ssp sativus) mesocosms for the first time. Experiments performed in the presence of carrot produced PFOS yields of up to 34% using a technical EtFOSA standard and up to 277% using Grão Forte, a commercial Sulfluramid bait formulation containing 0.0024% EtFOSA. Perfluorooctane sulfonamido acetate (FOSAA), perfluorooctane sulfonamide (FOSA), and perfluorooctanoic acid (PFOA) also formed over the course of the experiments, with the latter substance attributed to the presence of perfluorooctanamide impurities. The leachate contained low levels of transformation products and a high FOSA:PFOS ratio, consistent with recent observations in Brazilian surface water. In carrots, the more hydrophilic transformation products (e.g., PFOS) occurred primarily in the leaves, while the more hydrophobic products (e.g., FOSA, FOSAA, and EtFOSA) occurred in the peel and core. Remarkably, isomer-specific analysis revealed that the linear EtFOSA isomer biodegraded significantly faster than branched isomers. These data collectively show that the application of Sulfluramid baits can lead to the occurrence of PFOS in crops and in the surrounding environment, in considerably higher yields than previously thought. [ABSTRACT FROM AUTHOR]

Physiologically based pharmacokinetic (PBPK) modeling is a powerful in silico tool that can be used to simulate the toxicokinetics and tissue distribution of xenobiotic substances, such as perfluorooctanoic acid (PFOA), in organisms. However, most existing PBPK models have been based on the flow-limited assumption and largely rely on in vivo data for parametrization. In this study, we propose a permeability-limited PBPK model to estimate the toxicokinetics and tissue distribution of PFOA in male rats. Our model considers the cellular uptake and efflux of PFOA via both passive diffusion and transport facilitated by various membrane transporters, association with serum albumin in circulatory and extracellular spaces, and association with intracellular proteins in liver and kidney. Model performance is assessed using seven experimental data sets extracted from three different studies. Comparing model predictions with these experimental data, our model successfully predicts the toxicokinetics and tissue distribution of PFOA in rats following exposure via both IV and oral routes. More importantly, rather than requiring in vivo data fitting, all PFOA-related parameters were obtained from in vitro assays. Our model thus provides an effective framework to test in vitro-in vivo extrapolation and holds great promise for predicting toxicokinetics of per- and polyfluorinated alkyl substances in humans. [ABSTRACT FROM AUTHOR]

Despite growing concerns about human exposure to perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), other poly- and perfluoroalkyl substances (PFASs) derived from aqueous film-forming foams (AFFFs) have garnered little attention. While these other PFASs may also be present in AFFF-impacted drinking water, their removal by conventional drinking-water treatment is poorly understood. This study compared the removal of 30 PFASs, including 13 recently discovered PFASs, from an AFFF-impacted drinking water using carbonaceous sorbents (i.e., granular activated carbon, GAC). The approach combined laboratory batch experiments and modeling: batch sorption data were used to determine partition coefficients (K d) and calibrate a transport model based on intraparticle diffusion-limited sorption kinetics, which was used to make forward predictions of PFAS breakthrough during GAC adsorption. While strong retention was predicted for PFOS and PFOA, nearly all of the recently discovered polyfluorinated chemicals and PFOS-like PFASs detected in the AFFF-impacted drinking water were predicted to break through GAC systems before both PFOS and PFOA. These model breakthrough results were used to evaluate a simplified approach to predicting PFAS removal by GAC using compound-specific retention times on a C18 column (RTC18). Overall, this study reveals that GAC systems for the treatment of AFFF-impacted sources of water for PFOA and PFOS likely achieve poor removal, when operated only for the treatment of PFOS and PFOA, of many unmonitored PFASs of unknown toxicity. [ABSTRACT FROM AUTHOR]

Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was to investigate geochemical and hydrological processes governing the subsurface transport of PFASs at a former fire training area (FTA) on Cape Cod, Massachusetts, where PFAS-containing aqueous film-forming foams were used historically. A total of 148 groundwater samples and 4 sediment cores were collected along a 1200-m-long downgradient transect originating near the FTA and analyzed for PFAS content. The results indicate that unsaturated zones at the FTA and at hydraulically downgradient former domestic wastewater effluent infiltration beds both act as continuous PFAS sources to the groundwater despite 18 and 20 years of inactivity, respectively. Historically different PFAS sources are evident from contrasting PFAS composition near the water table below the FTA and wastewater-infiltration beds. Results from total oxidizable precursor assays conducted using groundwater samples collected throughout the plume suggest that some perfluoroalkyl acid precursors at this site are transporting with perfluoroalkyl acids. [ABSTRACT FROM AUTHOR]

More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain PFASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast number of PFASs on the market and in the environment. [ABSTRACT FROM AUTHOR]

Temporal and spatial trends of perfluoroalkyl acids (PFAAs) were investigated in Baltic Sea herring liver (Clupea harengus) from three sites, and white-tailed sea eagle (WTSE) eggs (Haliaeetus albicilla) from two freshwater and two marine areas in Sweden. Trends of most quantifiable PFAAs increased over the monitored period (1980-2014 in herring, 1960s/ 1980s -- 2010 in WTSE). No significant decreasing trends were observed for the most recent ten years for any substances, except perfluorooctane sulfonamide (FOSA). Concentrations of perfluorooctanesulfonic acids (PFOS) in herring showed a distinct decreasing spatial trend moving from the more southern site toward the more northern site, indicating main input of PFOS into the southern Baltic Sea. For WTSE, PFOS concentration was higher in the marine compared to the freshwater environment, explained by the cumulative historic contamination of the Baltic Sea. Similarly, concentrations in WTSE were lower in the northern part of the Baltic Sea compared to further south. Concentrations of PFUnDA, representing long-chain perfluoroalkyl carboxylic acids (PFCAs), showed a more homogeneous spatial distribution compared to PFOS for both herring and WTSE, indicating that atmospheric inputs (via precursors) of the long-chain PFCAs are important contributors in the study areas. [ABSTRACT FROM AUTHOR]

An extensive sampling campaign was undertaken to study the levels, isomer profiles and riverine mass discharges of perfluoroalkyl acids (PFAAs) and fluorinated alternatives in 19 Chinese rivers. The levels and homologue profiles of Σ10PFAAs varied considerably among the 19 rivers (mean 106; median 16.3, range 8.9-1240 ng/L), indicating the influence of specific point sources. Highly branched isomer profiles of perfluorooctanoic acid (18-25% br-PFOA) in rivers with elevated concentrations (96-352 ng/L) indicate that releases during production of PFOA by electrochemical fluorination and/or its use in fluoropolymer manufacture were the dominant sources to these rivers. The fluorinated alternatives 6:2 fluorotelomer sulfonate (detection frequency 21%, < 0.1-3.1 ng/L) and chlorinated polyfluoroalkyl ether sulfonate F-53B (51%, < 0.56-78.5 ng/L) were also found in some rivers. The total Chinese riverine mass discharges of PFOA (mean 80.9; range 16.8-168 t/y) (including monitoring data from this and other studies) were in good agreement with theoretical PFOA emission estimates (17.3-203 t/y) whereas riverine mass discharges of PFOS (mean 3.6; range 1.9-5.6 t/y) could only account for a minor fraction of theoretically estimated PFOS releases (70 t/y). This study provides empirical evidence that emissions from Chinese point sources likely dominate the global emissions of several legacy PFASs (notably PFOA) and fluorinated alternatives (e.g., F-53B). [ABSTRACT FROM AUTHOR]

Perfluorinated alkylated substances (PFASs) are today considered persistent, toxic, and bioaccumulative contaminants. Perfluorooctansulfonate (PFOS) and perfluorooctanoic acid (PFOA) are currently listed as priority substances under the UNEP global convention for the regulation of POPs. A previous study reported higher levels of PFASs in pine needles near ski areas. Their application as stain repellents in modern outdoor clothes and in ski waxes is assumed to be a potential source. Pine trees (Pinus mugo in Slovakia and Pinus sylvestris in Norway) were chosen for sampling in ski resorts. Relative distributions, overall concentrations, trend estimates, elevation patterns, and distance from primary sources were assessed. PFOA was the predominant PFAS constituent in pine needles from Slovakia (8-93%). In Norway, the most-abundant PFAS was perfluorobutanoic acid (PFBA: 3-66%). A difference in product composition (particularly in ski waxes) and differences in Norwegian and Slovakian regulations are considered to be the primary reason for these differences. Open application of PFOA in industry and products has been banned in Norway since 2011. The replacement of PFOA with short-chain substitutes is thus considered the reason for the observed pattern differences in the analyzed pine needles. Regular monitoring and screening programs are recommended. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA) is a perfluorocarboxylic acid that is difficult to treat by most conventional methods. As a result, it is often removed from solution by adsorption on powdered activated carbon (PAC), followed by incineration of the spent carbon. To provide a new approach for treatment, PFOA was exposed to sulfate radicals (SO4-) produced by thermolysis of persulfate (S2O82-) in the presence of PAC. Under acidic conditions, thermal activation of persulfate resulted in transformation of PFOA to shorter-chain-length perfluorinated compounds, as previously reported. However, when thermolysis of persulfate occurred under circumneutral pH conditions in the presence of PAC, a new removal pathway for PFOA was observed. Under these conditions, the removal of PFOA was attributable to chemisorption, a process in which PAC catalyzed persulfate decomposition and reacted with the transformation products to produce covalently bound PFOA. At PAC concentrations between 200 and 1000 mg/L and an initial PFOA concentration of 0.5 µM, covalent bonding resulted in removal of 10-40% of the PFOA. Under these conditions, the process resulted in removal of more than half of a more hydrophilic perfluoroalkyl acid (i.e., perfluorobutanoic acid, PFBA), which was greater than the amount of PFBA removed by physical adsorption on PAC. Although the high reaction temperatures (i.e., 80 °C) and relatively high doses of PAC used in this study may be impractical for drinking water treatment, this process may be applied to the treatment of these recalcitrant compounds in industrial wastewater, reverse osmosis concentrate, and other waters that contain high concentrations of PFOA and other perfluorocarboxylic acids. [ABSTRACT FROM AUTHOR]

To determine demographic, reproductive, and maternal dietary factors that predict perfluoroalkyl substance (PFAS) concentrations in breast milk, we measured perfluorooctane sulfonic (PFOS) and perfluorooctanoic acid (PFOA) concentrations, using liquid chromatography-mass spectrometry, in 184 colostrum samples collected from women participating in a cohort study in Eastern Slovakia between 2002 and 2004. During their hospital delivery stay, mothers completed a food frequency questionnaire, and demographic and reproductive data were also collected. PFOS and PFOA predictors were identified by optimizing multiple linear regression models using Akaike's information criterion (AIC). The geometric mean concentration in colostrum was 35.3 pg/mL for PFOS and 32.8 pg/mL for PFOA. In multivariable models, parous women had 40% lower PFOS (95% CI: -56 to -17%) and 40% lower PFOA (95% CI: -54 to -23%) concentrations compared with nulliparous women. Moreover, fresh/frozen fish consumption, longer birth intervals, and Slovak ethnicity were associated with higher PFOS and PFOA concentrations in colostrum. These results will help guide the design of future epidemiologic studies examining milk PFAS concentrations in relation to health end points in children. [ABSTRACT FROM AUTHOR]

The contribution of direct (i.e., uptake of perfluorooctanoic acid (PFOA) itself) and indirect (i.e., uptake of 8:2 fluorotelomer alcohol (FTOH) and metabolism to PFOA) exposure to PFOA serum concentrations was investigated using a dynamic one-compartment pharmacokinetic (PK) model. The PK model was applied to six occupationally exposed ski waxers for whom direct and indirect exposures via inhalation were characterized using multiple measurements with personal air sampling devices. The model was able to predict the diverging individual temporal trends of PFOA in serum with correlation coefficients of 0.82-0.94. For the four technicians with high initial concentrations of PFOA in serum (250-1050 ng/mL), the ongoing occupational exposure (both direct and indirect) was of minor importance and net depuration of PFOA was observed throughout the ski season. An estimated average intrinsic elimination half-life of 2.4 years (1.8-3.1 years accounting for variation between technicians and model uncertainty) was derived for these technicians. The remaining two technicians, who had much lower initial serum concentrations (10-17 ng/mL), were strongly influenced by exposure during the ski season with indirect exposure contributing to 45% of PFOA serum concentrations. On the basis of these model simulations, an average metabolism yield of 0.003 (molar concentration basis; uncertainty range of 0.0006-0.01) was derived for transformation of 8:2 FTOH to PFOA. An uncertainty analysis was performed, and it was determined that the input parameters quantifying the intake of PFOA were mainly responsible for the uncertainty of the metabolism yield and the initial concentration of PFOA in serum was mainly contributing to the uncertainty of estimated serum half-lives. [ABSTRACT FROM AUTHOR]

Cleavage of the strong carbon-fluorine bonds is critical for elimination of perfluorooctanoic acid (PFOA) from the environment. In this work, we investigated the decomposition of PFOA with the SiC/graphene catalyst under UV light irradiation. The decomposition rate constant (k) with SiC/graphene was 0.096 h-1, 2.2 times higher than that with commercial nano-TiO2. Surface fluorination on SiC/graphene was analyzed by X-ray photoelectron spectroscopy (XPS), revealing the conversions of Si-H bonds into Si-F bonds. A different route was found to generate the reactive Si-H bonds on SiC/graphene, substituting for silylium (R3Si+) to activate C-F bonds. During the activation process, photogenerated electrons on SiC transfer rapidly to perfluoroalkyl groups by the medium of graphene, further reducing the electron cloud density of C-F bonds to promote the activation. The hydrogen-containing hydrodefluorination intermediates including (CF3(CF2)2CFH, CF3(CF2)3CH2, CF3(CF2)4CH2, and CF3(CF2)4CFHCOOH) were detected to verify the hydrodefluorination process. The photoinduced hydrodefluorination mechanisms of PFOA can be consequently inferred as follows: (1) fluorine atoms in perfluoroalkyl groups were replaced by hydrogen atoms due to the nucleophilic substitution reaction via the Si-H/C-F redistribution, and (2) generation of CH2 carbene from the hydrogen-containing perfluoroalkyl groups and the C-C bonds scission by the Photo-Kolbe decarboxylation reaction under UV light excitation. This photoinduced hydrodefluorination provides insight into the photocatalytic decomposition of perfluorocarboxylic acids (PFCAs) in an aqueous environment. [ABSTRACT FROM AUTHOR]

The significance of perfluorooctanoic acid (PFOA) on the transport and deposition behaviors of bacteria (Gram-negative Escherichia coli and Gram-positive Bacillus subtilis) in quartz sand is examined in both NaCl and CaCl2 solutions at pH 5.6 by comparing both breakthrough curves and retained profiles with PFOA in solutions versus those without PFOA. All test conditions are found to be highly unfavorable for cell deposition regardless of the presence of PFOA; however, 7%-46% cell deposition is observed depending on the conditions. The cell deposition may be attributed to micro- or nanoscale roughness and/or to chemical heterogeneity of the sand surface. The results show that, under all examined conditions, PFOA in suspensions increases cell transport and decreases cell deposition in porous media regardless of cell type, presence or absence of extracellular polymeric substances, ionic strength, and ion valence. We find that the additional repulsion between bacteria and quartz sand caused by both acid-base interaction and steric repulsion as well as the competition for deposition sites on quartz sand surfaces by PFOA are responsible for the enhanced transport and decreased deposition of bacteria with PFOA in solutions. [ABSTRACT FROM AUTHOR]

Most children are exposed to perfluoroalkyl substances (PFASs) through placental transfer, breastfeeding, and other environmental sources. To date, there are no validated tools to estimate exposure and body burden during infancy and childhood. In this study, we aimed to (i) develop a two-generation pharmacokinetic model of prenatal and postnatal exposure to perfluorooctanoic add (PFOA), per- fluorooctanesulfonate (PFOS), and perfluorohexanesulfonate (PFHxS); and to (ii) evaluate it against measured children's levels in two studies. We developed a pharmacokinetic model consisting of a maternal and a child compartment to simulate lifetime exposure in women and transfer to the child across the placenta and through breastfeeding. To evaluate the model, we performed simulations for each mother--child dyad from two studies in which maternal PFAS levels at delivery and children's PFAS levels were available. Model predictions based on maternal PFAS levels, sex of child, body weight, and duration of breastfeeding explained between 52% and 60% of the variability in measured children's levels at 6 months of age and between 52% and 62% at 36 months. Monte Carlo simulations showed that the daily intake through breastfeeding and resulting internal PFAS levels can be much higher in nursing infants than in mothers. This pharmacokinetic model shows potential for postnatal exposure assessment in the context of epidemiological studies and risk assessment. [ABSTRACT FROM AUTHOR]

In this study, we investigated the destruction and by-product formation of perfluorooctanoic acid (PFOA) using ultraviolet light and persulfate (UV--PS). Additionally, we developed a first-principles kinetic model to simulate both PFOA destruction and by-product and chlorate (ClO3-) formation in ultrapure water (UW), surface water (SW), and wastewater (WW). PFOA degradation was significantly suppressed in the presence of chloride and carbonate species and did not occur until all the chloride was converted to ClO3- in UW and for low DOC concentrations in SW. The model was able to simulate the PS decay, pH changes, radical concentrations, and ClO3- formation for UW and SW. However, our model was unable to simulate PFOA degradation well in WW, possibly from PS activation by NOM, which in turn produced sulfate radicals. [ABSTRACT FROM AUTHOR]

Human exposure to perfluorooctanoic acid (PFOA) and other per- and polyfluoroalkyl substances (PFASs) is ongoing and in some cases increasing, despite efforts made to reduce emissions. The role of precursor compounds such as polyfluorinated phosphate esters (PAPs) has received increasing attention, but there are knowledge gaps regarding their occurrence and impact on human exposure. In this study, mono-, di-, and triPAPs, perfluorinated alkyl acids (PFAAs), saturated, and unsaturated fluorotelomer carboxylic acids (FTCA/FTUCAs), perfluoroalkane sulfonamides, and sulfonamidethanols (FOSA/FOSEs), and one fluorotelomer sulfonic acid (FTSA)) were compared in household dust samples from Canada, the Faroe Islands, Sweden, Greece, Spain, Nepal, Japan, and Australia. Mono-, di-, and triPAPs, including several diPAP homologues, were frequently detected in dust from all countries, revealing an ubiquitous spread in private households from diverse geographic areas, with significant differences between countries. The median levels of monoPAPs and diPAPs ranged from 3.7 ng/g to 1 023 ng/g and 3.6 ng/g to 692 ng/g, respectively, with the lowest levels found in Nepal and the highest in Japan. The levels of PAPs exceeded those of the other PFAS classes. These findings reveal the importance of PAPs as a source of PFAS exposure worldwide. [ABSTRACT FROM AUTHOR]

Comprehensive multiphase NMR is a novel NMR technique that permits all components (solutions, gels, and solids) to be studied in unaltered natural samples. In this study a wide range of CMP-NMR interaction and editing-based experiments are combined to follow contaminants (pentafluorophenol (PFP) and perfluorooctanoic acid (PFOA)) from the solution state (after a spill) through the gel-state and finally into the true solid-state (sequestered) in an intact water-swollen soil. Kinetics experiments monitoring each phase illustrate PFOA rapidly transfers from solution to the solid phase while for PFP the process is slower with longer residence times in the solution and gel phase. Interaction-based experiments reveal that PFOA enters the soil via its hydrophobic tails and selectively binds to soil microbial protein. PFP sorption shows less specificity exhibiting interactions with a range of gel and solid soil components with a preference toward aromatics (mainly lignin). The results indicate that in addition to more traditional measurements such as Koc, other factors including the influence of the contaminant on the soil-water interface, specific biological interactions, soil composition (content of lignin, protein, etc.) and physical accessibility/swellability of soil organic components will likely be central to better explaining and predicting the true behavior of contaminants in soil. [ABSTRACT FROM AUTHOR]

Methods to predict the bioaccumulation potential of per- and polyfluorinated alkyl substances (PFAS) are sorely needed, given the proliferation of these substances and lack of data on their properties and behavior. Here, we test whether molecular docking, a technique where interactions between proteins and ligands are simulated to predict both bound conformation and interaction affinity, can be used to predict PFAS binding strength and biological half-life. We show that an easy-to-implement docking program, Autodock Vina, can successfully redock perfluorooctanesulfonate (PFOS) to human serum albumin with deviations smaller than 2 Å. Furthermore, predicted binding strengths largely fall within one standard deviation of measured values for perfluorinated alkyl acids (PFAAs). Correlations with half-lives suggest both membrane partitioning and protein interactions are important, and that serum albumin is only one of a number of proteins controlling the fate of these chemicals in organisms. However, few data are available for validation of our approach as a broad screening tool, and available data are highly variable. We therefore call for collection of new data, particularly including proteins other than serum albumin and substances beyond perfluorooctanoic acid (PFOA) and PFOS. The methods we discuss in this work can serve as a framework for guiding such data collection. [ABSTRACT FROM AUTHOR]

To examine the effects of different functionalization methods on adsorption behavior, anionic-exchange MIL-101(Cr) metal-organic frameworks (MOFs) were synthesized using preassembled modification (PAM) and postsynthetic modification (PSM) methods. Perfluorooctanoic acid (PFOA) adsorption results indicated that the maximum PFOA adsorption capacity was 1.19 and 1.89 mmol g-1 for anionic-exchange MIL-101(Cr) prepared by PAM and PSM, respectively. The sorption equilibrium was rapidly reached within 60 min. Our results indicated that PSM is a better modification technique for introducing functional groups onto MOFs for adsorptive removal because PAM places functional groups onto the aperture of the nanopore, which hinders the entrance of organic contaminants. Our experimental results and the results of complementary density functional theory calculations revealed that in addition to the anion-exchange mechanism, the major PFOA adsorption mechanism is a combination of Lewis acid/base complexation between PFOA and Cr(III) and electrostatic interaction between PFOA and the protonated carboxyl groups of the bdc (terephthalic acid) linker. [ABSTRACT FROM AUTHOR]

The production and use of long-chain perfluoroalkyl substances (PFASs) must comply with national and international regulations. Driven by increasingly stringent regulations, their production has been outsourced to less regulated countries in Asia. In addition, the fluoropolymer industry started to use fluorinated alternatives, such as 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoic acid (HFPO-DA). Between August 2013 and September 2014, we investigated the occurrence and distribution of HFPO-DA and legacy PFASs in surface waters of the following river/estuary systems: the Elbe and Rhine Rivers in Germany, the Rhine-Meuse delta in The Netherlands, and the Xiaoqing River in China. Distinct differences were revealed among the study areas; notably, the Chinese samples were highly polluted by an industrial point source discharging mainly perfluorooctanoic acid (PFOA). This particular point source resulted in concentrations more than 6000 times higher than an industrial point source observed in the Scheur River, where HFPO-DA was the dominant compound with a concentration of 73.1 ng/L. Moreover, HFPO-DA was detected in all samples along the coastline of the North Sea, indicating that the compound may be transported from the Rhine-Meuse delta into the German Bight via the water current. To the best of our knowledge, the fluorinated alternative, HFPO-DA, was detected for the first time in surface waters of Germany and China. [ABSTRACT FROM AUTHOR]

Food is a major source of human exposure to perfluorooctanoic acid (PFOA), however, PFOA bioavailability in food has not been studied. An in vivo mouse model and three in vitro methods (unified BARGE method, UBM; physiologically based extraction test, PBET; and in vitro digestion method, IVD) were used to determine the relative bioavailability and bioaccessibility of PFOA in the presence of 17 foods. PFOA was mixed with foods of different nutritional compositions and fed to mice over a 7-d period. PFOA relative bioavailability was determined by comparing PFOA accumulation in the liver following PFOA exposure via food to that in water. PFOA bioavailability relative to water ranged from 4.30 ± 0.80 to 69.0 ± 11.9% and was negatively correlated with lipid content (r = 0.76). This was possibly due to competitive sorption of free fatty acids with PFOA onto transporters on intestine epithelial cells. Besides, cations in the gastrointestinal tract, such as Ca2+ and Mg2+, are capable of complexing PFOA and partitioning to the lipid phase. On the other hand, when assessed using in vitro assays, PFOA bioaccessibility varied with methods, being 8.7-73% (UBM), 9.8-99% (PBET), and 21-114% (IVD). PFOA bioaccessibility was negatively correlated with lipid content when assessed using UBM (r = 0.82); however, a poor correlation with food composition was observed for PBET and IVD (r = 0.01-0.50). When in vivo and in vitro data were compared, a strong correlation was observed for UBM (r = 0.79), but poor relationships were observed for PBET and IVD (r = 0.11-0.22). This was probably because the higher lipolysis ability and presence of Ca2+ and Mg2+ in the gastrointestinal fluid of UBM resulted in a lower potential to form stable micelles compared to PBET and IVD. These results indicated that PFOA relative bioavailability was mainly affected by lipid content in foods, and UBM has the potential to determine PFOA bioaccessibility in food samples. [ABSTRACT FROM AUTHOR]

Perfluorinated chemicals (PFCs) are of concern due to their widespread use, persistence in the environment, tendency to accumulate in animal tissues, and growing evidence of toxicity. Between 2006 and 2011 we collected blood plasma from 261 bald eagle nestlings in six study areas from the upper Midwestern United States. Samples were assessed for levels of 16 different PFCs. We used regression analysis in a Bayesian framework to evaluate spatial and temporal trends for these analytes. We found levels as high as 7370 ng/mL for the sum of all 16 PFCs (ΣPFCs). Perfluorooctanesulfonate (PFOS) and perfluorodecanesulfonate (PFDS) were the most abundant analytes, making up 67% and 23% of the PFC burden, respectively. Levels of ΣPFC, PFOS, and PFDS were highest in more urban and industrial areas, moderate on Lake Superior, and low on the remote upper St. Croix River watershed. We found evidence of declines in ΣPFCs and seven analytes, including PFOS, PFDS, and perfluorooctanoic acid (PFOA); no trend in two analytes; and increases in two analytes. We argue that PFDS a long-chained PFC with potential for high bioaccumulation and toxicity, should be considered for future animal and human studies. [ABSTRACT FROM AUTHOR]

Estimated historical exposures and serum concentrations of perfluorooctanoic acid (PFOA) have been extensively used in epidemiologic studies that examined associations between PFOA exposures and adverse health outcomes among residents in highly exposed areas in the Mid-Ohio Valley. Using measured serum PFOA levels in 2005-2006, we applied two calibration methods to these retrospective exposure predictions: (l) multiplicative calibration and (2) Bayesian pharmacokinetic calibration with larger adjustments to more recent exposure estimates and smaller adjustments to exposure estimates for years farther in the past We conducted simulation studies of various hypothetical exposure scenarios and compared hypothetical true historical intake rates with estimates based on mis-specified baseline exposure and pharmacokinetic models to find the method with the least bias. The Bayesian method outperformed the multiplicative method if a change to bottled water consumption was not reported or if the half-life of PFOA was mis- specified. On the other hand, the multiplicative method outperformed the Bayesian method if actual tap water consumption rates were systematically overestimated. If tap water consumption rates gradually decreased over time because of substitution with bottled water or other liquids, neither method clearly outperformed another. Calibration of retrospective exposure estimates using recently collected biomarkers may help reduce uncertainties in environmental epidemiologic studies. [ABSTRACT FROM AUTHOR]

The electrochemical mineralization mechanism of environmentally persistent perfluorooctanoic acid (PFOA) at a Ce-doped modified porous nanocrystalline PbO2 film anode was investigated using density functional theory (DFT) simulation and further validated experimentally. The potential energy surface was mapped out for all possible reactions during electrochemical mineralization reaction of PFOA. The hydroxyl radical (-OH), O2 and H2O took part in the mineralization process and played different roles. The OH-initiated process was found to be the main degradation pathway, and the existence of O2 obviously accelerated the degradation process of PFOA in aqueous solution. On the basis of the DFT calculations, an optimal electrochemical mineralization mechanism of PFOA was proposed, which involved the electronic migration, decarboxylation, radical reaction, hydrogen abstraction reaction, and radical fragmentation reaction. The proposed mechanism was verified by the dynamics and intermediate determination experiments. Furthermore, the observed -OH concentration showed that the electrolysis system could produce enough OH for PFOA mineralization process, indicating that the proposed -OH-initiated process derived from DFT calculations was feasible. These insightful findings are instrumental for a comprehensive understanding of the mineralization of PFOA in the electrolysis system. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were previously detected (⩾4 ng/L) in 65% and 30%, respectively, of 23 New Jersey (NJ) public drinking water systems (PWS) sampled in 2006. We now report on a 2009 study of the occurrence of PFOA, PFOS, and eight other perfluorinated compounds (PFCs) in raw water samples from 30 intakes (18 groundwater and 12 surface water) from 29 additional NJ PWS. Between 1 and 8 PFCs were detected (⩾5 ng/L) in 21 (70%) of 30 PWS samples at total PFC concentrations of 5-174 ng/L. Although PFOA was the most commonly detected PFC (57% of samples) and was found at the highest maximum concentration (100 ng/L), some ot the higher levels of other PFCs were at sites with little or no PFOA. Perfluorononanoic acid was detected more frequently (30%) and at higher concentrations (up to 96 ng/L) than in raw or finished drinking water elsewhere, and it was found at several sites as the sole or predominant PFC, a pattern not reported in other drinking water studies. PFOS, perfluoropentanoic acid, and perfluo rohexanoic acid were each detected in more than 20% of samples, while peril uoroheptan oic acid, perfluo rob utane sulfonic acid, and perfluo rohexane sulfonic acid were detected less frequently. Perfluorobutanoic acid was found only once (6 ng/L), and pertluorodecanoic acid was not detected. Total PFCs were highest in two reservoirs near an airfield; these were also the only sites with total perfluorosulfonic acids higher than total perfluorocarboxylic acids (PFCAs). PFC levels in raw and finished water from the same source were similar at those sites where both were tested. Five wells of two additional NJ PWS known to be contaminated with PFOA were also each sampled 4-9 times in 2010-13 for nine of the same PFCs. Total PFCs (almost completely PFCAs) at one of these PWS located near an industrial source of PFCs were higher than in any other PWS tested (up to 330 ng/L). These results show that multiple PFCs are commonly found in raw water from NJ PWS. Future work is needed to develop approaches for assessing the potential human health risks of exposure to mixtures of PFCs found in drinking water and other environmental media. [ABSTRACT FROM AUTHOR]

Perfluorinated compounds (PFCs) are known to accumulate in liver and induce hepatotoxicity on experimental animals. Liver fatty acid binding protein (LFABP) is expressed highly in hepatocytes and binds fatty acids. PFCs may bind with FABP and change their ADME and toxicity profile. In the present study, the binding interaction of 17 structurally diverse PFCs with human L-FABP was investigated to assess their potential disruption effect on fatty acid binding. The binding affinity of twelve perfluorinated carboxylic acids (PFCAs), as determined by fluorescence displacement assay, increased significantly with their carbon number from 4 to 11, and decreased slightly when the number was over 11. The three perfluorinated sulfonic acids (PFSAs) displayed comparable affinity, but no binding was detected for the two fluorotelomer alcohols. Circular dichroism results showed that PFC binding induced distinctive structural changes of the protein. Molecular docking revealed that the driving forces for the binding of PFCs with FABP were predominantly hydrophobic and hydrogen-bonding interactions, and the binding geometry was dependent on both the size and rigidity of the PFCs. Based on the binding constant obtained in this work, the possibility of in vivo competitive displacement of fatty acids from FABP by PFCs was estimated. [ABSTRACT FROM AUTHOR]

The acid dissociation constants (pKas) of perfluoroalkyl carboxylic acids (PFCAs) have been the subject of discussion in the literature; for example, values from -0.2 to 3.8 have been suggested for perfluorooctanoic acid (PFOA). The dissociated anionic conjugate bases of PFCAs have negligible air-water partition coefficients (KAWs) and do not volatilize from water. The neutral acids, however, have relatively high KAWs and volatilization from water has been demonstrated. The extent of volatilization of PFCAs in the environment will depend on the water pH and their pKa. Knowledge of the pKas of PFCAs is therefore vital for understanding their environmental transport and fate. We investigated the water-to-air transfer of PFCAs in a novel experimental setup. We used ∼1 μg L-1 of PFCAs in water (above environmental background concentrations but below the concentration at which self-association occurs) at different water pH (pH 0.3 to pH 6.9) and sampled the PFCAs volatilized from water during a 2-day experiment. Our results suggest that the pKas of C4-11 PFCAs are <1.6. For PFOA, we derived a pKa of 0.5 from fitting the experimental measurements with a volatilization model. Perfluoroalkane sulfonic acids were not volatilized, suggesting that their pKas are below the investigated pH range (pKa <0.3). [ABSTRACT FROM AUTHOR]

Although levels of poly- and perfluoroalkyl substances (PFASs) in human maternal and neonatal blood have been widely reported in the literature, relationship of maternal-fetal transmission of PFASs with carbon chain length is presently not well understood. In this study, 11 PFASs were analyzed in matched samples, including not only maternal blood (MB, n = 31) and cord blood (CB, n = 30), but also placenta (n = 29) and amniotic fluid (AF, n = 29). Except for perfluorohexanoic acid (PFHxA), the detection frequencies of PFASs were similar among placenta, MB, and CB (>80% for 8 PFASs, nondetectable for 2 PFASs). Though only perfluorooctanoic acid (PFOA) was frequently detected (>90%) in AF, with a median concentration of 0.043 ng/mL, other 5 PFASs were also detectable in AF samples with low concentrations (mean: 0.013-0.191 ng/mL). This suggests that in addition to blood-borne in utero exposure, the fetus is also exposed to low levels of PFASs through AF. Concentrations of PFOA in AF were positively correlated with those in MB (r = 0.738, p < 0.01) and CB (r = 0.683, p < 0.001), suggesting that AF concentration could reflect fetal PFOA exposure during pregnancy and can be used as a biomarker. To clarify the effects of carbon chain length on maternal transfer of PFASs, we calculated maternal transfer efficiencies of PFASs from MB to CB (TMB-CB). A U-shaped trend in TMB-CB of C7-C12 perfluoroalkyl carboxylic acids (PFCAs) with increasing carbon chain length was found in this study for the first time. The U-shaped TMB-CB of PFCAs with carbon chain length is an integrated result of opposite trend of the ratios between MB/placenta and placenta/CB based on carbon chain length. This is the first study to report the occurrence of PFASs in human placenta. The results reported here enable better understanding of the maternal-fetal transmission of PFASs. [ABSTRACT FROM AUTHOR]

Toxicity of perfluorooctanoic acid (PFOA) and triazoles, that is, paclobutrazol (PBZ) and triadimefon (TDF), singly and in binary mixtures was assessed on the benthic cladoceran Chydorus sphaericus. Following single exposure, toxicity of PBZ was not significantly different from that of TDF as shown by the overlapping 95% confidence intervals of their median effective concentrations: EC50PBZ = 0.07-0.09 mM; EC50TDF = 0.066-0.078 mM. PFOA was far less toxic than these triazoles: EC50PFOA = 0.20-0.24 mM. Assuming no interactions between PFOA and the triazoles, the toxicity of PFOA in mixtures with the triazoles estimated by the concentration addition (CA) and independent action (IA) models was significantly lower than its toxicity in single exposure. This contrasted with the results for PBZ and TDF. Based on the assumption that PFOA may interact with the triazoles, different predictions were obtained by the two models. Significant alleviation of PBZ and TDF on the toxicity of PFOA was found by the extended CA model only. According to the extended IA model, PFOA had nonsignificant effects on the toxicity of PBZ while significantly increasing the toxicity of TDF. This difference is possibly related to different modes of actions for various functional groups in PBZ and TDF. [ABSTRACT FROM AUTHOR]

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have received high concerns due to their extreme persistence, and very few technologies have been reported for their complete destruction. For sound PFCs wastes disposal, mechanochemical method was employed using a planetary ball mill. Potassium hydroxide (KOH) was identified as the best comilling reagent and nearly complete destruction of both PFOS and PFOA was realized. The measured water-soluble fluoride accounted for most of the organic fluorine. The final products of PFOS after treatment were shown to be KF and K2SO4 by XRD analysis. The mass ratio between PFOS and KOH significantly affected the fluoride recovery but not for PFOS destruction and the sulfate recovery. The gradual formation of sulfate and fluoride reveals that the degradation of PFOS is initiated with the dissociation of the sulfonate group. FTIR spectra further showed the disappearance of the -CF3 and -CF2- groups with the generation of sulfate. The cleavage of C-F bonds in PFOS and the formation of fluoride ion were also identified by XPS spectra. On the basis of these results, possible reaction pathways were proposed. The approach was also successfully applied for the destruction of PFOS and PFOA homologues with different chain lengths. [ABSTRACT FROM AUTHOR]

A mass balance was assembled for perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and perfluorooctanesulfonic acid (PFOS) in the Baltic Sea. Inputs (from riverine discharge, atmospheric deposition, coastal wastewater discharges, and the North Sea) and outputs (to sediment burial, transformation of the chemical, and the North Sea), as well as the inventory in the Baltic Sea, were estimated from recently published monitoring data. Formation of the chemicals in the water column from precursors was not considered. River inflow and atmospheric deposition were the dominant inputs, while wastewater treatment plant (WWTP) effluents made a minor contribution (<5%). A mass balance of the Oder River watershed was assembled to explore the sources of the perfluoroalkyl acids (PFAAs) in the river inflow. It indicated that WWTP effluents made only a moderate contribution to riverine discharge (21% for PFOA, 6% for PFOS), while atmospheric deposition to the watershed was 1-2 orders of magnitude greater than WWTP discharges. The input to the Baltic Sea exceeded the output for all four PFAAs, suggesting that inputs were higher during 2005-2010 than during the previous 20 years despite efforts to reduce emissions of PFAAs. One possible explanation is the retention and delayed release of PFAAs from atmospheric deposition in the soils and groundwater of the watershed. [ABSTRACT FROM AUTHOR]

A total of 420 human plasma samples from two cities (Halle and Münster, Germany), collected between 1982 and 2009, were analyzed for a suite of PFCAs (C6-C12) and selected PFCA precursors (4:2-, 4:2/6:2-, 6:2-, 6:2/8:2-, 8:2-, 8:2/10:2-, and 10:2-diPAPs). PFCAs (C7-C11 and C13) were detected in over 80% of the samples (<0.005-39.4 ng/mL), while C12 PFCA was detected in fewer than 10% of the samples. In a range of 10-46% of the samples, 4:2-, 4:2/6:2-, 6:2, and 8:2-diPAPs were identified at concentrations of <0.0002-0.687 ng/mL; fewer than 10% of the samples had detectable 10:2-diPAP. Temporal trends (2000-2009) showed increasing concentrations of PFNA, PFDA, and PFUnDA, whereas PFOA concentrations were decreasing. Calculated population halving time for PFOA varied between 8.2-14.5 years, which contrasts to the generally accepted value of 3.8 years. This suggests an ongoing or additional exposure to PFOA or one of its precursor compounds. DiPAPs, known to metabolize rapidly to PFCAs, were detected in a significant number of samples and at concentrations that have not declined significantly over the past half-decade. The evidence suggests they have contributed to the continued presence of the longer chain PFCAs and perhaps contribute to the slow decline of PFOA. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl substances are manmade chemicals used in many consumer products and have become ubiquitous in the environment. Animal studies and a limited number of human studies have demonstrated developmental effects in offspring exposed to perfluoroalkyl substances in utero, but the implications of timing of in utero exposure have not been systematically investigated. The present study investigated variation in perfluorocarbon levels of 9952 women of childbearing age who had been exposed to perfluorooctanoic acid (PFOA) in drinking water contaminated by industrial waste. An analysis of variance with contrast was performed to compare the levels of PFOA and perfluorooctanesulfonic acid (PFOS) in pregnant and nonpregnant women overall and during each trimester of pregnancy. We found that pregnant women had lower circulating PFOA and PFOS concentrations in peripheral blood than nonpregnant women and that PFOA levels were consistently lower throughout all trimesters for pregnancy, suggesting transfer to the fetus at an early stage of gestation. These results are discussed in the context of the endocrine-disrupting properties of perfluoroalkyl substances that have been characterized in animal and human studies. Our conclusion is that further, systematic study of the potential implications of intrauterine perfluorocarbon exposure during critical periods of fetal development is urgently needed. [ABSTRACT FROM AUTHOR]

The spatial distribution of 10 perfluoroalkyl acids including linear and branched (six monotrifluoromethyl isomers) perfluorooctane sulfonate (PFOS) in surface water was investigated in Huai River Basin and Taihu Lake in Jiangsu Province, China. In the water samples from Huai River Basin, perfluorooctanoic acid (PFOA) and PFOS were the predominant compounds (mean 18 ng/L and 4.7 ng/L, respectively), while in samples from Taihu Lake, PFOA, perfluorohexanoic acid (PFHxA), and PFOS were the predominant compounds (mean 56 ng/L, 19 ng/L, and 15 ng/L, respectively). Branched PFOS (Br-PFOS) isomers accounting for 48.1% to 62.5% of total PFOS were enriched in all samples from Taihu Lake, compared to technical electrochemical fluorination (ECF) PFOS (Br-PFOS ∼30.0%), while the similar phenomena were not found in samples from Huai River Basin (Br-PFOS 29.0-35.0%). Principal component analysis (PCA) on the percentages of the individual isomer showed that the first two components accounted for 78.4% and 15.3% of the overall observed data variance. Samples from Huai River Basin were grouped together with the ECF PFOS standard suggesting the profiles were similar, while samples from Taihu Lake were grouped by themselves, suggesting that isomer profiles in these samples were different from that of Huai River Basin. The obvious difference in isomer profiles probably results from the different environmental behaviors of PFOS isomers and/or unknown sources (PFOS or PFOS precursors). [ABSTRACT FROM AUTHOR]

Perfluoroalkyl acids (PFAAs) have been reported to interfere with the endocrine system in vivo by mimicking endogenous hormone activities and causing adverse effects. Some exoestrogens bind to estrogen receptor (ER) and subsequently induce an ER-mediated response. The transcriptional activity of ER is regulated by its distinct conformational states that are the results of ligand binding. In this work, a biosensor based on surface plasmon resonance (SPR) technique was developed which can discriminate between agonist and antagonist of human ERα (hERα) by monitoring the conformation state of the protein induced by ligand binding. The biosensor utilized the specific interaction between hERα and conformation-selective peptides. Six PFAAs with different chain lengths and acid groups were tested by the biosensor, and perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were found to be ER agonists. Kinetic analyses of direct interaction between PFAAs and hERα by SPR revealed that PFOS and PFOA were both weak binders of ER with KD values of 2.19 and 107 μM respectively, whereas the other four PFAAs did not bind with ER. To understand the differences in ER binding affinity and estrogenic activity among the six PFAAs, molecular docking based on the crystal structure of hERα ligand binding domain was performed. PFOS and PFOA were efficiently docked with hERα and formed hydrogen bonds with Arg394 in a manner similar to estradiol. Overall, the two 8-carbon PFAAs were assessed as weak agonists of hERα and are of potential concern. [ABSTRACT FROM AUTHOR]

Polyfluorinated amides (PFAMs) are a class of compounds produced as byproducts of polyfluorinated sulfonamide synthesis by electrochemical fluorination (ECF). We measured four PFAM derivatives of perfluorooctanoic acid (PFOA) in a wide range of compounds, experimental materials, and commercial products synthesized by ECF. Initial screening was performed using headspace solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), and quantification using in-house synthesized standards was accomplished with GC-MS using positive chemical ionization. Two monosubstituted PFAMs, N-methylperfluorooctanamide (MeFOA) and N -ethylperfluorooctanamide (EtFOA), were detected in the majority of materials that were analyzed. Two disubstituted PFAMs, N-methyl-N-(2- hydroxyethyl)perfluorooctanamide (MeFOAE) and N-ethyl-N-(2- hydroxyethyl)perfluorooctanamide (EtFOAE), were not detected in any sample, likely because they were never synthesized. The concentrations of PFAMs in the sulfonamide compounds under study ranged from 12 to 6736 μg/g, suggesting their historical importance as PFCA precursors. In each case, branched isomers for PFAMs were detected, providing further support for their link to an ECF source. A hydrolysis study performed at pH 8.5 showed no degradation of EtFOA to PFOA after 8 days due to the stability of the amide bond. The environmental fate of PFAMs is suggested to be volatilization to the atmosphere followed by oxidation by hydroxyl radical with a predicted lifetime of 3–20 days. Subsequent PFAM exposure to biota will likely lead to enzymatic hydrolysis of the amide linkage to give a PFCA. Human exposure to PFAMs may have contributed to the presence of branched PFOA isomers in blood by serving as an indirect source. The decline in PFOA concentrations in human blood is consistent with a significant drop in PFAM production concurrent with the POSF phase-out in 2000–2001. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (C7F15COOH, PFOA) has increasingly attracted worldwide concerns due to its global occurrence and resistance to most conventional treatment processes. Though TiO2-based photocatalysis is strong enough to decompose most organics, it is not effective for PFOA decomposition. We first find that indium oxide (In2O3) possesses significant activity for PFOA decomposition under UV irradiation, with the rate constant about 8.4 times higher than that by TiO2. The major intermediates of PFOA were C2-C7 shorter-chain perfluorocarboxylic acids, implying that the reaction proceeded in a stepwise manner. By using diffuse reflectance infrared Fourier transform spectroscopy, 19F magic angle spinning nuclear magnetic resonance, and electron spin resonance, we demonstrate that the terminal carboxylate group of PFOA molecule tightly coordinates to the In2O3 surface in a bidentate or bridging configuration, which is beneficial for PFOA to be directly decomposed by photogenerated holes of In2O3 under UV irradiation, while PFOA coordinates to TiO2 in a monodentate mode, and photogenerated holes of TiO2 preferentially transform to hydroxyl radicals, which are inert to react with PFOA. PFOA decomposition in wastewater was inhibited by bicarbonate and other organic matters; however, their adverse impacts can be mostly avoided via pH adjustment and ozone addition. [ABSTRACT FROM AUTHOR]

A laboratory investigation on the biotransformation of 8:2 fluorotelomer stearate monoester (8:2 FTS) in aerobic soils was conducted by monitoring the loss of 8:2 FTS, production of 8:2 fluorotelomer alcohol (8:2 FTOH) and stearic acid, which would be released by cleavage of the ester linkage, and subsequent degradation products from FTOH for 80 d. Soil microcosms were extracted with ethyl acetate followed by two heated 90/10 v/ v acetonitrile/200 mM NaOH extractions. 8:2 FTS was degraded with an observed half-life (t½) of 103 d. The rate of 8:2 FTS biotransformation substantially decreased after 20 d with 22% of 8:2 FTS still remaining on day 80. No biotransformation of 8,2 FTS occurred in autoclaved soil controls, which remained sterile with 102 ± 6% recovery, through day 20. 8:2 FTOH was generated with cleavage of the ester linkage of 8:2 FTS followed by a rapid decline (t½ ∼ 2 d) due to subsequent biodegradation. All the expected 8:2 FTOH degradation products were detected including 8:2 fluorotelomer unsaturated and saturated carboxylic acids, 7:2s FTOH, 7:3 acid, and three perfluoroalkyl carboxylic acids with the most prominent being perfluorooctanoic acid (PFOA). PFOA consistently increased over time reaching 1.7 ± 0.07 mol % by day 80. Although cleavage of the ester linkage was evidenced by 8:2 FTOH production, an associated trend in stearic acid concentrations was not clear because of complex fatty acid metabolism dynamics in soil. Further analysis of mass spectrometry fragmentation patterns and chromatography supported the conclusion that hydrolysis of the ester linkage is predominantly the first step in the degradation of 8:2 FTS with the ultimate formation of terminal products such as PFOA. [ABSTRACT FROM AUTHOR]

The behavior of polyfluoralkyl acids (PFAAs) from intake (raw source water) to finished drinking water was assessed by taking samples from influent and effluent of the several treatment steps used in a drinking water production chain. These consisted of intake, coagulation, rapid sand filtration, dune passage, aeration, rapid sand filtration, ozonation, pellet softening, granular activated carbon (GAC) filtration, slow sand filtration, and finished drinking water. In the intake water taken from the Lek canal (a tributary of the river Rhine), the most abundant PFAA were PFBA (perfluorobutanoic acid), PFBS (perfluorobutane sulfonate), PFOS (perfluorooctane sulfonate), and PFOA (perfluorooctanoic acid). During treatment, longer chain PFAA such as PFNA (perfluorononanoic acid) and PFOS were readily removed by the GAC treatment step and their GAC effluent concentrations were reduced to levels below the limits of quantitation (LOQ) (0.23 and 0.24 ng/L for PFOS and PFNA, respectively). However, more hydrophilic shorter chain PFAA (especially PFBA and PFBS) were not removed by GAC and their concentrations remained constant through treatment. A decreasing removal capacity of the GAC was observed with increasing carbon loading and with decreasing carbon chain length of the PFAAs. This study shows that none of the treatment steps, including softening processes, are effective for PFAA removal, except for GAC filtration. GAC can effectively remove certain PFAA from the drinking water cycle. The enrichment of branched PFOS and PFOA isomers relative to non branched isomers during GAC filtration was observed during treatment. The finished water contained 26 and 19 ng/L of PFBA and PFBS. Other PFAAs were present in concentrations below 4.2 ng/L The concentrations of PFAA observed in finished waters are no reason for concern for human health as margins to existing guidelines are sufficiently large. [ABSTRACT FROM AUTHOR]

We aimed to investigate the role of indoor office air on exposure to polyfluorinated compounds (PFCs) among office workers. Week-long, active air sampling was conducted during the winter of 2009 in 31 offices in Boston, MA. Air samples were analyzed for fluorotelomer alcohols (FTOHs), sulfonamides (FOSAs), and sulfonamidoethanols (FOSEs). Serum was collected from each participant (n = 31) and analyzed for 12 PFCs including PFOA and PFOS. In air, FTOHs were present in the highest concentrations, particularly 8:2-FTOH (GM = 9920 pg/m³). FTOHs varied significantly by building with the highest levels observed in a newly constructed building. PFOA in serum was significantly correlated with air levels of 6:2-FTOH (r = 0.43), 8:2-FTOH (r = 0.60), and 10:2-FTOH (r = 0.62). Collectively, FTOHs in air significantly predicted PFOA in serum (p < 0.001) and explained approximately 36% of the variation in serum PFOA concentrations. PFOS in serum was not associated with air levels of FOSAs/FOSEs. In conclusion, FTOH concentrations in office air significantly predict serum PFOA concentrations in office workers. Variation in PFC air concentrations by building is likely due to differences in the number, type, and age of potential sources such as carpeting, furniture, and/or paint. [ABSTRACT FROM AUTHOR]

The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors. [ABSTRACT FROM AUTHOR]

In animals, perfluorinated chemicals (PFCs), specifically perfluorooctanoic acid (PFOA) and perfluorooctane sulfate (PFOS), function as peroxisome proliferator-activated receptor (PPAR) alpha agonists. However, the relevance of animal (primarily rodent) data to humans is unresolved. While plasma adiponectin level is very responsive to PPAR gamma agonist drugs, it has not been determined whether adiponectin level is related to serum PFCs concentrations. In the present study, 287 subjects (12-30 years of age) were recruited to determine the relationship between serum level of PFCs and serum level of adiponectin. The results showed males had higher serum PFOS concentrations than females and that those with metabolic syndrome had lower serum PFOA than controls. Besides, it showed regional elevations of the perfluoroundecanoic acid (PFUA) (median concentration: 7.11 ng/mL) in the study subjects. No relationship of PFOA, PFOS, PFUA, and the sum of all four PFCs was found to glucose homeostasis, adiponectin level, lipid profile, and inflammatory markers. The median and the range of perfluorononanoic acid (PFNA) concentration (in ng/mL; for four categories corresponding to the <50, 50-74, 75-89, and =90th percentiles) were 0.38 (0.38-1.68), 3.22 (1.73-4.65), 5.85 (4.75-8.29), 10.56 (8.40-25.40), respectively. After controlling for confounding factors, multiple linear regression analysis revealed that the mean natural log-transformed level of adiponectin increased significantly across categories of PFNA (in ng/mL; 8.78, 8.73, 9.06, 9.36; P for trend = 0.010 in the full model). In conclusion, higher serum PFNA concentration is associated with elevated serum adiponectin concentration. [ABSTRACT FROM AUTHOR]

Recently, the role of diffuse inputs of perfluoroalkyl acids (PFAAs) into surface waters has been investigated. It has been observed that river loads increased during rain and that street runoff contained considerable loads of PFAAs. This study aims at quantifying these diffuse inputs and identifying the initial sources in a small nonindustrial river catchment. The river was sampled in three distinct subcatchments (rural, urban, and wastewater treatment plant) at high temporal resolution during two rain events and samples were analyzed for perfluorocarboxylates and perfluorosulfonates. Additionally, rain, stormwater runoff, wastewater effluent, and drinking water were sampled. PFAA concentrations in river water were all low (e.g., < 10 ng/L for perfluorooctanoate, PFOA), but increased during rainfall. PFAA concentrations and water discharge data were integrated into a mass balance assessment that shows that 30-60% of PFAA loads can be attributed to diffuse inputs. Rain contributed 10-50% of the overall loads, mobilization of dry deposition and outdoor release of PFAA from products with 20-60%. We estimated that within a year 2.5-5 g of PFOA originating from rain and surface runoff are emitted into this small catchment (6 km², 12?500 persons). [ABSTRACT FROM AUTHOR]

The effects of exposure concentration on the bioaccumulation of four perfluorinated chemicals (PFCs): perfluorooctanesulfonate (PFOS), perfluoroocanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), was investigated using green mussels, Perna viridis. Mussels were exposed to concentrations of 1 μgL-1 and 10 μgL-1 of each PFC for 56 days, and the bioaccumulation factors (BAF) were found to range from 15 to 859 L/kg and from 12 to 473 L/kg at 1 μgL-1 and 10 μgL-1, respectively. For all compounds, the BAF was larger at the lower dosage. Results suggest that the bioaccumulation of PFCs is concentration dependent. This concentration dependency can be explained by a nonlinear adsorption mechanism, which was further supported by the experimental results. The sensitivity of BAF to exposure concentration was found to be positively related to perfluorinated chain length and the binding affinity of the compounds. Bioaccumulation of long chain carboxylates and sulfonates are more easily affected by concentration changes. The validity of the conventional kinetic method was examined by comparing the results with the fundamental steady-state method: in addition to the above-mentioned batch test, mussels were also subject to 24-day exposure (1 μgL-1 and 10 μgL-1) followed by 24-day depuration. Contradictions were found in the resulting kinetic BAF and model curving fittings. A new kinetic model based on adsorption mechanism was proposed, which potentially provide more accurate description of the bioaccumulation process of PFCs. [ABSTRACT FROM AUTHOR]

Removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from aqueous solution has attracted wide attention in light of their environmental persistence, bioaccumulation, and potential toxicity. Although various destructive technologies were developed, removal of PFOX (X = A and S) under mild conditions are still desirable. In this work, multiwalled carbon nanotubes (MWNTs) were applied to remove PFOX in electrochemically assistant adsorption. Electrosorption kinetics and isotherms were investigated relative to open circuit (OC) adsorption and adsorption on powder MWNTs. Compared with powder MWNTs adsorption, the initial adsorption rate (?0) of 100 μg/L PFOX at 0.6 V increased 60-fold (PFOA) and 41-fold (PFOS) according to pseudosecond-order kinetics model and the maximum electrosorption capacity (qm) of PFOX (50 μg/L to 10 mg/L) increased 150-fold (PFOA) and 94-fold (PFOS) simulated with Langmuir model. These significant improvements were assumed to benefit from enhanced electrostatic attraction under electrochemical assistance. Furthermore, the used MWNTs were found to be regenerative and reusable. This work provides not only a new approach to effective removal of perfluorochemicals from aqueous solution but also a low energy-consumption and environmentally-friendly strategy for application of carbon nanotubes in water treatment. [ABSTRACT FROM AUTHOR]

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are used in a variety of industrial and consumer products and have been detected worldwide in human blood. The sources for human exposure are not well described, but dietary intake is suggested as an important source. In this study of 652 Danish men from the Diet, Cancer and Health cohort, we examined intake of 10 major dietary groups, tap water drinks, alcohol consumption, cooking method, geographical area, age, smoking status, and BMI as potential determinants of PFOA and PFOS plasma levels. Living in the Aarhus area was associated with higher PFOA and PFOS plasma levels compared with living in the Copenhagen area, and never smokers had higher levels than current smokers. Frying as compared with other cooking methods was a determinant of PFOA and PFOS levels. BMI and alcohol consumption were inversely associated with both compounds. Among the dietary groups, only intake of eggs was significantly positively associated with PFOS plasma levels. In future studies, PFOA and PFOS levels in air, dust and water samples should be measured to elucidate further the sources of exposure; exposure through diet needs to be studied in greater detail. Our finding of a higher body burden of PFOA and PFOS among never smokers also warrants further evaluation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the concentration trends of a nine-target-analyte homologous series of perfluorocarboxylates from six American Red Cross adult blood donor centers. A total of 645 serum and 600 plasma samples were obtained in 2000-2001 and 2006, respectively, with samples stratified for each 10-year (20-69) age- and sex-group per each location. Samples were extracted by protein precipitation and quantified by using tandem mass spectrometry. The nine perfluorocarboxylates were perfluorobutanoate (PFBA, C3F7CO2-), perfluoropentanoate (PFPeA, C4F9CO2-), perfluorohexanoate (PFHxA, C5F11CO2-), perfluoroheptanoate (PFHpA, C6F13CO2-), perfluorooctanoate (PFOA, C7F15CO2-), perfluorononanoate (PFNA, C8F17CO2-), perfluorodecanoate (PFDA, C9F19CO2-), perfluoroundecanoate (PFUnA,C10F21CO2-), and perfluorododecanoate (PFDoA, C11F23CO2-). The majority of measurements were less than the lower limit of quantitation for PFPeA, PFHxA, and PFDoA. For the remaining targeted analytes, the geometric mean serum and plasma concentrations (ng/mL) for 2000-2001 and 2006 were, respectively, as follows: PFBA 2.61 vs 0.33, PFHpA 0.13 vs 0.09, PFOA 4.70 vs 3.44, PFNA 0.57 vs 0.97, PFDA 0.16 vs 0.34, and PFUnA 0.10 vs 0.18. Estimates of the 95th percent tolerance limits (ng/mL) were as follows: PFBA 5.3 vs 1.4, PFHpA 0.4 vs 0.4, PFOA 12.3 vs 7.7, PFNA 1.4 vs 2.2, PFDA 0.4 vs 0.8, and PFUnA 0.3 vs 0.5. Important observations were the decline in PFBA and increase in PFNA, PFDA, and PFUnA concentrations between 2000-2001 and 2006. The longer chain length perfluorocarboxylates were also highly correlated with each other. [ABSTRACT FROM AUTHOR]

Interest and concern about polyfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and an increasing number of other related compounds is growing as more is learned about these ubiquitous anthropogenic substances. Many of these compounds can be toxic, and they are regularly found in the blood of animals and humans worldwide. A great deal of research has been conducted in this area, but a surprising amount remains unknown about their distribution in the environment and how people ultimately become exposed. The utility of these compounds seems to ensure their continued use in one form or another for the foreseeable future, presenting a long-term challenge to scientists, industry leaders, and public health officials worldwide. [ABSTRACT FROM AUTHOR]

Animal studies suggest that perfluorocarbons (PFCs) may alter sexual maturation. Relationships of human PFC exposure with puberty are not clear. We conducted a cross-sectional study to investigate whether perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were associated with indicators of sexual maturation in a 2005-2006 survey of residents with PFOA water contamination from the Mid-Ohio Valley. Participants were 3076 boys and 2931 girls aged 8-18 years. They were classified as having reached puberty based on either hormone levels (total >50 ng/dL and free >5 pg/mL testosterone in boys and estradiol >20 pg/mL in girls) or onset of menarche. We estimated the odds of having reached puberty classified by these criteria and the fitted median age of reaching puberty in relation to serum PFOA and PFOS concentrations measured when puberty status was assigned. For boys, there was a relationship of reduced odds of reached puberty (raised testosterone) with increasing PFOS (delay of 190 days between the highest and lowest quartile). For girls, higher concentrations of PFOA or PFOS were associated with reduced odds of postmenarche (130 and 138 days of delay, respectively). In conclusion, our study showed a later age of puberty in this population correlated with PFC concentrations. [ABSTRACT FROM AUTHOR]

Background: Perfluorinated chemicals (PFCs) have been used widely in consumer products since the 1950s and are currently found at detectable levels in the blood of humans and animals across the globe. In stark contrast to this widespread exposure to PFCs, there is relatively little research on potential adverse health effects of exposure to these chemicals. Objectives: We performed this cross-sectional study to determine if specific blood PFC levels are associated with impaired response inhibition in children. Methods: Blood levels of 11 PFCs were measured in children (N = 83) and 6 PFCs: perfluorooctane sulfonate (PFOS), perfluorohexane sulfate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctanesulfonamide (PFOSA), and perfluorodecanoic acid (PFDA) - were found at detectable levels in most children (87.5% or greater had detectable levels). These levels were analyzed in relation to the differential reinforcement of low rates of responding (DRL) task. This task rewards delays between responses (i.e., longer inter-response times; IRTs) and therefore constitutes a measure of response inhibition. Results: Higher levels of blood PFOS, PFNA, PFDA, PFHxS, and PFOSA were associated with significantly shorter IRTs during the DRL task. The magnitude of these associations was such that IRTs during the task decreased by 29-34% for every 1 SD increase in the corresponding blood PFC. Conclusions: This study suggests an association between PFC exposure and children's impulsivity. Although intriguing, there is a need for further investigation and replication with a larger sample of children. [ABSTRACT FROM AUTHOR]