Higher Perfluorooctanoic Acid Concentrations Research Articles

Ecotoxicity of perfluorooctanoic acid and perfluorooctane sulfonate on aquatic plant Vallisneria natans.

Perfluorinated compounds (PFCs) are persistent organic contaminants that are highly toxic to the environment and bioaccumulate, but their ecotoxic effects on aquatic plants remain unclear. In this study, the submerged plant Vallisneria natans was treated with short-term (7 days) and long-term (21 days) exposures to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentrations of 0, 0.01, 0.1, 1.0, 5.0, and 10 mg/L, respectively. The results showed that both high concentrations of PFOA and PFOS inhibited the growth of V. natans and triggered the increase in photosynthetic pigment content in leaves. The oxidative damage occurred mainly in leaves, but both leaves and roots gradually built up tolerance during the stress process without serious membrane damage. Both leaves and roots replied to short-term stress by activating superoxide dismutase (SOD), catalase (CAT) and polyphenol oxidase (PPO), while peroxidase (POD) was involved under high concentration stress with increasing exposure time. Leaves showed a dose-effect relationship in integrated biomarker response (IBR) values under short-term exposure, and the sensitivity of roots and leaves to PFOS was higher than that of PFOA. Our findings help to increase knowledge of the toxic effects of PFCs and have important reference value for risk assessment and environmental remediation of PFCs in the aquatic ecosystem.

Per/polyfluoroalkyl substances modulate plasmid transfer of antibiotic resistance genes: A balance between oxidative stress and energy support

Emerging contaminants can accelerate the transmission of antibiotic resistance genes (ARGs) from environmental bacteria to human pathogens via plasmid conjugation, posing a great challenge to the public health. Although the toxic effects of per/polyfluoroalkyl substances (PFAS) as persistent organic pollutants have been understood, it is still unclear whether and how PFAS modulate the transmission of ARGs. In this study, we for the first time reported that perfluorooctanoic acid (PFOA), perfluorododecanoic acid (PFDoA) and ammonium perfluoro (2-methyl-3-oxahexanoate) (GenX) at relatively low concentrations (0.01, 0.1 mg/L) promoted the conjugative transfer of plasmid RP4 within Escherichia coli, while the plasmid conjugation was inhibited by PFOA, PFDoA and GenX at relatively high concentrations (1, 10 mg/L). The non-unidirectional conjugation result was ascribed to the co-regulation of ROS overproduction, enhanced cell membrane permeability, shortage of energy support as well as l-arginine pool depletion. Taking the well-known PFOA as an example, it significantly enhanced the conjugation frequency by 1.4 and 3.4 times at relatively low concentrations (0.01, 0.1 mg/L), respectively. Exposure to PFOA resulted in enhanced cell membrane permeability and ROS overproduction in donor cells. At high concentrations of PFOA (1, 10 mg/L), although enhanced oxidative stress and cell membrane permeability still occurred, the ATP contents in E. coli decreased, which contributed to the inhibited conjugation. Transcriptome analysis further showed that the expression levels of genes related to arginine biosynthesis (argA, argC, argF, argG, argI) and transport (artJ, artM, artQ) pathways were significantly increased. Intracellular l-arginine concentration deficiency were observed at high concentrations of PFOA. With the supplementary exogenous arginine, it was demonstrated that arginine upregulated conjugation transfer- related genes (trfAp, trbBp) and restores the cell number of transconjugants in PFOA-treated group. Therefore, the inhibited conjugation at high concentrations PFOA were attributed to the shortage of ATP and the depletion of L-arginine pool. These findings provide important insights into the effect environmental concentrations of PFAS on the conjugative transfer of ARGs, and update the regulation mechanism of plasmid conjugation, which is critical for the management of antibiotic resistance in aquatic environments.

Elevated Maternal Testosterone Levels Alter PFOA Elimination and Tissue Distribution in Pregnant Rats.

Perfluorooctanoic acid (PFOA) is an enduring synthetic chemical that harms human health. Recent studies indicate heightened bioaccumulation of PFOA, particularly in pregnant women experiencing preeclampsia. Since plasma testosterone levels are elevated in pregnant women with preeclampsia, we hypothesized that hyperandrogenic conditions during pregnancy may hinder PFOA elimination and contribute to their higher body burden. Pregnant Sprague-Dawley rats were s/c injected with vehicle or testosterone propionate from gestational day (GD) 15 to 20 to increase plasma testosterone levels by 2-fold, similar to levels in preeclampsia. On GD 16, [14C]-PFOA (9.4 pmol/kg) was given intravenously, and subsequently, 14C radioactivity was measured in maternal blood, urine, feces, and tissues. PFOA was primarily eliminated through urine; however, less PFOA was excreted in urine of pregnant rats with elevated testosterone levels than controls. Fecal excretion of PFOA was minimal and did not significantly differ between groups. The total elimination of PFOA (urine plus feces) was significantly reduced by 12% in pregnant rats with elevated testosterone levels. In controls, PFOA distribution was highest in placenta, followed by the kidneys, liver, brain, heart, lungs, and spleen. Pregnant rats with elevated testosterone levels displayed 12% higher concentrations of PFOA in these tissues than controls. Furthermore, the renal expression of Oat2 and Oat3 was significantly decreased, while Oatp1 and Oat-k expression was significantly increased in pregnant rats with elevated testosterone levels than controls. In conclusion, elevated maternal testosterone levels decrease urinary elimination of PFOA, possibly through altered expression of renal transporters leading to increased tissue concentrations of PFOA in pregnant rats.

Plasma concentrations of perfluoroalkyl acids and their determinants in youth and adults from Nunavik, Canada

Perfluoroalkyl acids (PFAAs), a subset of per- and poly-fluoroalkyl substances (PFAS), are environmentally stable, mobile and bioaccumulative compounds. This leads to high concentrations in wildlife species essential to the cultural identity and subsistence of Arctic populations. Our objective was to characterize the distribution and exposure determinants of PFAAs among Nunavik Inuit adults. The study included up to 1322 Nunavik residents aged 16–80 years who participated in the Qanuilirpitaa? 2017 Nunavik Inuit Health Survey (Q2017). Plasma concentrations were compared to those the general Canadian population using data from the Canadian Health Measures Survey Cycle 5 (2016–2017). Associations between plasma concentrations of nine PFAAs, determined by liquid chromatography-tandem mass spectrometry, and sociodemographic factors and traditional activity participation were examined using multiple linear regression models. Overall exposure to PFAAs was twice as high compared to the general Canadian population and less regulated perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUnDA) concentrations were 7-fold higher, and perfluorodecanoic acid (PFDA) concentrations were 4-fold higher. Males had higher concentrations of perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS), whereas females had higher concentrations of PFDA and PFUnDA. PFAAs concentrations increased with age and were highest among those aged 60+ years. PFNA and PFOA concentrations followed a J-shaped pattern: those aged 16–29 years had higher concentrations than those aged 20–29 and 30–39 years. Ungava Bay generally had lower concentrations of all PFAAs congeners compared to Hudson Bay and Hudson Strait, with the exception of PFNA, which tended to have the lowest concentration in Hudson Strait. PFAAs concentrations were highly associated with hunting activity, omega-3 polyunsaturated fatty acids, and drinking water from environmental sources. The results highlight the importance of characterizing PFAAs exposure sources in Arctic communities and provide further evidence for the long-range transport of long-chain PFAAs and their precursors that necessitate international action.

Elevated exposure to long-chain perfluoroalkyl and polyfluoroalkyl substances (PFAS) in Inuit from Nunavik, Arctic Canada: a call for global action

BACKGROUND AND AIM: The Inuit of Nunavik are exposed to perfluoroalkyl acids (PFAAs) via long-rang transport from southern to northern latitudes and biomagnification of PFAAs in Arctic food webs. Our objective was to document plasma PFAAs levels and compare them to previously documented levels and the general Canadian population. METHODS: The study included 1326 Nunavimmiut aged 16-82 years from the population representative survey, Qanuilirpitaa? 2017 Nunavik Inuit Health Survey. Concentrations of nine PFAAs were assessed, including perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUdA). Concentrations were compared to Nunavik levels in 2004, other Arctic regions, and the Canadian Health Measures Survey (CHMS) Cycle 5 2016-2017. Multiple linear regression analyses compared concentrations by demographics and lifestyle. RESULTS: There were elevated concentrations of various PFAAs congeners compared to CHMS, including PFOS, and long-chain PFAS congeners, PFNA, PFDA, and PFUnDA. PFNA and PFUdA concentrations were 7-fold higher than the CHMS concentrations, and PFDA concentrations were almost 4-fold higher than the CHMS concentrations. Short-chain congeners were largely undetected. Concentrations differed by sex, age, region, and indicators of seafood and marine mammal consumption. Males had higher concentrations of PFOA and PFHxS, whereas females had higher concentrations of PFDA and PFUdA. PFAAs concentrations increased with age and were highest among those aged 50+ years, such that serum PFOS concentrations were 2.5 times higher in those aged 50+ years compared to those aged 16-29 years. PFNA concentrations followed a U-shaped curve with increasing age. CONCLUSIONS: Our findings indicate a decrease in older PFAAs, but concentrations of many PFAAs in Nunavik remain several-fold higher compared to the general Canadian population. Evidence also points to an increase in exposure to long-chain PFAAs, which are an emerging public health concern in the Arctic. KEYWORDS: PFAS, Indigenous, Environmental justice, Exposure

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

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

Perfluoroalkane acids in human milk under the global monitoring plan of the Stockholm Convention on Persistent Organic Pollutants (2008–2019)

Within the global monitoring plan (GMP) established by article 16 of the Stockholm Convention on Persistent Organic Pollutants, perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) are recommended for analysis in core matrices to assess occurrence and changes geographically and with time. In 101 samples consisting of 86 national pools and 15 pools from States in Brazil obtained between 2008 and 2019, PFHxS was detected in 17% of the national pools and none in Brazil. PFOA and PFOS had a detection frequency of 100% and 92%, respectively. Other perfluoroalkane substances (PFAS) had either low detection frequencies and median values of zero (carboxylic acids C4–C11; except PFOA) or could not be quantified in any sample (sulfonic acids, C4–C10, and long-chain carboxylic acids, C12–C14). Correlation between PFOA and PFOS was moderately (r = 0.58). Whereas median values were almost identical (18.9 pg/g f.w. for PFOS; 18.6 pg/g f.w. for PFOA), PFOS showed larger ranges (< 6.2 pg/g f.w.−212 pg/g f.w.) than PFOA (< 6.2 pg/g f.w.−63.4 pg/g f.w.). It was shown that wealthier countries had higher PFOA concentrations than poorer countries. No difference in concentrations was found for samples collected in countries having or not having ratified the Stockholm Convention amendments to list PFOS or PFOA. The goal to achieve 50% decrease in concentrations within ten years was met by Antigua and Barbuda, Kenya, and Nigeria for PFOS and by Antigua and Barbuda for PFOA. In a few cases, increases were observed; one country for PFOS, four countries for PFOA.

Anaerobic degradation of perfluorooctanoic acid (PFOA) in biosolids by Acidimicrobium sp. strain A6

Anaerobic incubations were performed with biosolids obtained from an industrial wastewater treatment plant (WWTP) that contained perfluorooctanoic acid (PFOA), and with per- and polyfluoroalkyl substances- (PFAS) free, laboratory-generated, biosolids that were spiked with PFOA. Biosolid slurries were incubated for 150 days as is, after augmenting with either Acidimicrobium sp. Strain A6 or ferrihydrite, or with both, Acidimicrobium sp. Strain A6 and ferrihydrite. Autoclaved controls were run in parallel. Only the biosolids augmented with both, Acidimicrobium sp. Strain A6 and ferrihydrite showed a decrease in the PFOA concentration, in excess of 50% (total, dissolved, and solid associated). Higher concentrations of PFOA in the biosolids spiked with PFOA and no previous PFAS exposure allowed to track the production of fluoride to verify PFOA defluorination. The buildup of fluoride over the incubation time was observed in these biosolid incubations spiked with PFOA. A significant increase in the concentration of perfluoroheptanoic acid (PFHpA) over the incubations of the filter cake samples from the industrial WWTP was observed, indicating the presence of a non-identified precursor in these biosolids. Results show that anaerobic incubation of PFAS contaminated biosolids, after augmentation with Fe(III) and Acidimicrobium sp. Strain A6 can result in PFAS defluorination.

Electrochemical destruction and mobilization of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in saturated soil

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have attracted attention due to their widespread distribution, recalcitrance, and substantial toxicity. In this work, high concentrations of PFOA and PFOS were degraded and mobilized through electrochemical treatments in a simulated source zone of saturated soil. Under a low constant voltage and direct current of 24 V and 467–690 mA, approximately 51.7% and 33% of PFOA and PFOS were degraded, respectively. Additionally, a total defluorination mass balance of 44.7% and 23% were detected for PFOA and PFOS, respectively, which indicates that the removal of PFOA and PFOS occurs through its destruction. Substantial electromigration causes the destruction and mobilization of solid PFOA and PFOS to shift into the water phase. Although electrochemical oxidation of PFAS (per- and polyfluoroalkyl substances) were previously reported and studied, this study is one of the few that focus on simultaneous desorption, mobilization, and destruction of PFAS in saturated soil containing a low-intensity electrical field.

Ineffectiveness of ultrasound at low frequency for treating per- and polyfluoroalkyl substances in sewage sludge

Concerns have been raised about per- and polyfluoroalkyl substances (PFAS) in sewage sludge given the urgent need of finding suitable disposal methods for sludge. In this study, we evaluated the effect of ultrasonication on PFAS changes in sewage sludge. It was revealed that although ultrasonication at 20 kHz increased the soluble chemical oxygen demand (SCOD) of treated sewage sludge, this technique was ineffective for degrading perfluoroalkyl acids (PFAAs) and their precursors. Ultrasonic treatment for longer time (>15 min) led to concentration increase of perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA), and perfluorohexanoic acid (PFHxA) in the liquid phase, possibly due to their release from disrupted sludge flocs during cavitation. Adding permanganate (10 mM) to the ultrasonic system could also enhance the disruption of sludge particles, resulting in higher concentrations of PFOA and PFHxA in the solid phase and PFOA, PFHpA, PFHxA, and perfluorobutanesulfonic acid (PFBS) in the liquid phase. Overall, ultrasonic pretreatment at 20 kHz and 0.7 W/mL is unlikely to remove PFAS from sewage sludge. Instead, it could increase the risk of PFAS pollution upon final sludge disposal. Effective treatment technologies are thus demanded if PFAS in sludge are regulated.

Gestational perfluoroalkyl substance exposure and body mass index trajectories over the first 12 years of life.

Background/Objectives:Gestational exposure to perfluoroalkyl substances (PFAS), a ubiquitous class of persistent endocrine disrupting chemicals, is associated with increased risk of obesity and cardiometabolic disease. However, it is unclear if gestational PFAS exposure is associated with adiposity trajectories related to adult obesity and cardiometabolic health.Subjects/Methods:We measured perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononaoic acid, and perfluorohexanesulfonic acid (PFHxS) concentrations in maternal serum collected between 16-weeks gestation and delivery in a cohort of 345 mother-child pairs in Cincinnati, OH (enrolled 2003–06). From age 4-weeks to 12 years, we measured weight and length or height up to eight times and calculated child BMI (1,865 repeated measures). Using covariate-adjusted linear mixed models and splines to account for repeated BMI measures and non-linear BMI patterns, respectively, we estimated the age/magnitude of infancy BMI zenith (~1 year) and childhood BMI nadir (~5 years), BMI accrual from 8–12 years, and BMI at age 12 years by PFAS terciles.Results:BMI trajectories varied by PFOA concentrations (age × PFOA interaction p-value=0.03). Children born to women with higher PFOA concentrations had lower infancy and early childhood BMI, earlier BMI nadir, accelerating BMI gains in mid-childhood and adolescence, and higher BMI at age 12 years. Some of these associations were non-monotonic. PFOS and PFHxS were not associated with alterations in BMI trajectories, but were monotonically associated with lower BMI across infancy, childhood, and adolescence. Compared to children in the 1st PFOS tercile, those in the 2nd (β:-0.83; 95%CI:-2.11, 0.51 kg/m2) and 3rd (β:-1.41; 95%CI:-2.65, -0.14 kg/m2) had lower BMI at age 12 years.Conclusions:These results suggest that gestational PFOA exposure may be associated with BMI trajectories related to adult obesity and cardiometabolic disease, while PFOS and PFHxS exposure is associated with lower BMI in the first 12 years of life.

Gestational perfluoroalkyl substance exposures and early adolescent bone mineral density in the HOME Study

Background/Aim: Perfluoroalkyl substances (PFAS) may impair bone health via endocrine disruption and nuclear hormone receptor activation. Bone mineral accrual during adolescence is important for long-term bone health, but human studies of PFAS and bone mineral density are primarily in adults or use a cross-sectional study design. We estimated associations of gestational PFAS exposures with early adolescent areal bone mineral density (aBMD) in a prospective cohort study. Methods: We examined 225 pregnant mothers enrolled from 2003-2006 in Cincinnati, OH and their children in the HOME Study. We measured concentrations of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononaoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS) in maternal serum collected at 16 weeks gestation. When children were 12 years old, we measured lean body mass and total body, spine, total hip, femoral neck, and distal forearm (1/3 radius) aBMD with dual x-ray absorptiometry and calculated height-, age-, sex-, and race-specific aBMD z-scores. Using linear regression, we estimated covariate-adjusted associations in aBMD z-scores per doubling of gestational PFAS concentrations overall and stratified by sex. We estimated the proportion of total effects that were mediated by lean mass using structural equation modeling. Results: In adjusted models, higher PFOA concentrations were associated with lower aBMD z-scores of the forearm (β: -0.28, 95% CI: -0.49, -0.08), total hip (β: -0.28, 95% CI: -0.54, -0.02), and spine (β: -0.34, 95% CI: -0.61, -0.06) in males but not females. Lean mass mediated 29-50% of these associations. Higher PFHxS and PFNA concentrations were associated with lower aBMD z-scores of the forearm (PFHxS β: -0.11, 95% CI: -0.23, 0.00; PFNA β: -0.14, 95% CI: -0.35, 0.06), with no modification by sex or mediation by lean mass. PFOS was not associated with aBMD measures in either sex. Conclusions: Gestational PFAS exposures may reduce bone accrual in early adolescence, possibly in a sex-dependent manner.

Concentration, spatial distribution, and health risk assessment of PFASs in serum of teenagers, tap water and soil near a Chinese fluorochemical industrial plant

Discharges released from fluorochemical industrial plants lead to severe contamination of the environment with per- and polyfluoroalkyl substances (PFASs), which may pose risks to human health. In this study, 187 serum samples from teenagers (age = 14 years), 22 tap water samples and 40 soil samples were collected in areas within 0–11 km of a fluorochemical industrial plant in Huantai County, Shandong Province, and concentrations of 18 PFASs were quantified by UPLC-MS/MS. Perfluorooctanoic acid (PFOA) was found to be predominant, concentrations of which ranged from 40.4 to 845 ng/mL in serum, from 2.88 to 19.3 ng/L in tap water, from 4.40 to 189 ng/g in soil, and accounting for 84.1–98.6%, 15.9–79.8%, and 73.8–96.7% of the total PFASs, respectively. Statistical analysis demonstrated that concentrations of perfluorinated carboxylic acids (PFCAs) in soil (C5-C9) and serum (C8-C10) were associated with the industrial plant. And PFOA concentrations in tap water were not relevant to the industrial plant, which were comparable with the non-contaminated area and lower than the threshold value recommended by U.S. EPA (70 ng/mL), indicating that the contribution to the high concentration of serum PFOA of local teenagers by drinking water was limited. Moreover, PFCAs in soil only made a limited contribution to the serum PFCAs of local residents by direct inhalation and dermal exposure, but the potential health risk by the soil via food chain should be paid attention to. Furthermore, health risk assessment demonstrated that high concentrations of PFOA in serum could pose potential health risk to local teenagers. Therefore, effective measures should be taken to attenuate the health risks caused by the industrial plant to local residents, and further epidemiological studies should be carried out in the future.

Concentration- and nutrient-dependent cellular responses of microalgae Chlorella pyrenoidosa to perfluorooctanoic acid

Perfluorooctanoic acid (PFOA), an emerging and persistent pollutant, could cause toxicity effects on aquatic organisms. However, this was generally assessed under high exposure concentrations of PFOA and nutrient-enriched conditions, which was not accordant with the actual environments. Therefore, to comprehensively understand the toxicity effects of PFOA on aquatic organisms, the cellular responses of microalgae, Chlorella pyrenoidosa, to PFOA under different concentrations (≤ 1.0 mg/L) and nutrient conditions were investigated in this study. Results show that PFOA at concentrations less than 1.0 mg/L had no significant effects on algal growth and chlorophyll contents, and no oxidative damages were generated to destroy membrane integrity and morphology. However, N,P-limited and -starved conditions significantly decreased algal growth and chlorophyll contents, and induced oxidative stresses to ruin the structure and function of cell membrane. Moreover, the deficiency of P had more severe negative effect on algae than that of N, and they both influenced the toxicity responses of microalgae to 1.0 mg/L PFOA. The adsorption and uptake percentages of PFOA by algal cells were both less than 10%, and increased adsorption but decreased uptake of PFOA amounts occurred under N,P-limited and -starved conditions. These findings will be useful to understand the toxicity effects of PFOA on microalgae in aquatic environments.

Fluorinated fire-figthing foams: manufacture, applications, ecological consequences

Information on the production and use of fluorine-containing foaming agents intended for foam extinguishing of fires with oils and other flammable liquids as well as ecological consequences are reviewed in the article. It is shown that poly- and/or perfluorinated compounds usage for fire-fighting foam production led to the emergence of a large group of hazardous chemicals in the environment, including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS). General information about fluorine-containing foaming agents, their manufacturers and labelling, properties, possible volumes of production and application on a global scale are given. It is shown that the use of fire-fighting foam to extinguish fires, as well as during training, leads to direct discharges of PFOS, PFOA and other fluorine-containing compounds into the environment. The results of studies carried out in various EU countries, Norway, the USA, Canada and Australia, which testify to high concentrations of PFOS, PFOA and other fluoride-containing compounds in groundwater and surface waters as well as in soils, are discussed. The highest levels of contamination are found in the sites where fluorine-containing foaming agents are used. The danger of fluoride-containing compounds entering the human body with contaminated drinking water and food products is shown.

Pollution pathways and release estimation of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in central and eastern China.

China has gradually become the most important manufacturing and consumption centre for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in the world, and inadvertently become the world's major contamination hotspots. However, a systematic analysis of pollution pathways for PFOS/PFOA into the different environmental compartments and their quantification in China has yet to be carried out. This study focused on PFOS and PFOA release into the environment in the central and eastern region of China, which accounts for the vast majority of national emission. About 80-90% of PFOS/PFOA contamination in the Chinese environment was estimated to come directly from manufacturing and industrial sites mostly via wastewater discharge from these facilities. The other major contamination sources for PFOS were identified as being linked to aqueous fire-fighting foams (AFFFs), and pesticides including sulfluramid. For PFOA, following some way behind industrial wastewater, were industrial exhaust gas, domestic wastewater and landfill leachate as contamination sources. For surface water contamination, the major pollution contributors after industrial wastewater were AFFF spill runoff for PFOS, and domestic wastewater and precipitation-runoff for PFOA. The majority of PFOS that contaminated soil was considered to be linked with infiltration of AFFF and pesticides, while most PFOA in soil was attributed to atmospheric deposition and landfill leachate. Where groundwater had become contaminated, surface water seepage was estimated to contribute about 50% of PFOS and 40% of PFOA while the remainder was mostly derived from soil leaching. A review of the available monitoring data for PFOS/PFOA in the literature supported the view that industrial wastewater, landfill leachate and AFFF application were the dominant sources. Higher concentrations of PFOA than PFOS found in precipitation also corroborated the prediction of more PFOA release into air. To reduce PFOS/PFOA contamination of the Chinese environment the focus for control should be on industrial wastewater emissions.

Identify biosorption effects of Thiobacillus towards perfluorooctanoic acid (PFOA): Pilot study from field to laboratory

The concentration of Perfluoroalkyl acids (PFAAs) and the bacterial community composition along the Xiaoqing River were explored with HPLC-MS/MS and Illumina high-throughput sequencing in present study. The results showed that perfluorooctanoic acid (PFOA) was the predominant PFAAs in all sediment samples, and high level of PFOA could lead to an evident increase in the abundance of Thiobacillus. Thiobacillus was identified with the survival ability in high concentrations of PFOA accordingly. Therefore, Thiobacillus thioparus and Thiobacillus denitrificans were selected as receptors to design indoor biosorption experiment. The growth curves under different PFOA concentrations and residual rates of PFOA in the processes of cultivation were analyzed. The results showed that upwards concentrations of PFOA below 5000 ng/L led to an obvious increase in the growth rate of T. thioparus. Whereas PFOA promoted the growth of T. denitrificans in a relatively limited range of concentration, and the effect was not obvious. The addition of different concentrations of PFOA had no apparent effects on pH values in the media of both T. thioparus and T. denitrificans. The concentrations of PFOA in liquid media reduced after the process of bacteria culturing. The removal rates of T. thioparus and T. denitrificans to PFOA were 21.1–26.8% and 13.5–18.4%, respectively. The current findings indicated that T. thioparus could play a significant role as potential biosorbent with the ability to eliminate PFOA effectively in aquatic environment, which would provide novel information for PFOA ecological decontamination and remediation.

The Investigation of Perfluorinated Compounds in Surface Waters of the Xixi Wetland, Hangzhou, China.

The distribution patterns of perfluorinated compounds (PFCs) in the surface waters of Xixi wetland, China, were investigated for the first time. Among the eight PFCs investigated, only perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA) and perfluorononanoic acid (PFNA) were detected. PFOA was the most prominent PFC, and detected in all of the samples with higher PFOA concentrations (maximum: 197.8ngL-1), followed by PFHpA (maximum: 3.97ngL-1). Geographical differences in PFC levels were not observed among various sampling locations except for the YanShan River location, but seasonal changes have been observed for PFOA. The study suggested that the water diversion project from the Qiantang River to the Xixi Wetland may have significantly contributed to the increase of PFOA level, and that domestic sewage and farmland irrigation runoff are constant pollution sources to the Xixi Wetland.

Removal of perfluorooctanoic acid (PFOA) in groundwater by nanofiltration membrane.

Perfluorooctanoic acid (PFOA) is very persistent in the environment and resistant to typical degradation processes. PFOA has been widely used in surface-active agents and as an emulsifier in several products and can contaminate groundwater. Groundwater is considered as an important source of water; hence removal of PFOA contamination in groundwater is needed. This study aimed to examine the removal of PFOA in spiked deionized water and spiked groundwater samples by nanofiltration (NF) membrane. PFOA removal efficiency was performed by using NF membrane and all samples were analysed by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). For groundwater concentration, solid phase extraction is needed before being analysed by HPLC-MS/MS. The results showed that at higher pressures and higher PFOA concentrations, the PFOA removal efficiencies were slightly higher. The PFOA removal efficiency of spiked deionized water and spiked groundwater sample were 99.78-99.87% and 99.49-99.54%, respectively, which were not significantly different.

Chemisorption of Perfluorooctanoic Acid on Powdered Activated Carbon Initiated by Persulfate in Aqueous Solution.

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 (S2O8(2-)) 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.