Perfluoroheptanoic Acid Research Articles

Association of maternal exposure to perfluoroalkyl and polyfluroalkyl substances with infant growth from birth to 12 months: A prospective cohort study

BackgroundAlthough maternal perfluoroalkyl and polyfluroalkyl substances (PFASs) were associated with adverse birth outcomes, much less is known about their impact on infant growth during early infancy. ObjectivesWe investigated the association between maternal PFASs exposure and infant growth during the first 12 months of life. MethodsParticipating 2395 pregnancies were recruited from Shanghai Birth Cohort between 2013 and 2016. Ten PFASs were quantified from maternal plasma collected during early pregnancy (median, 15 gestational weeks). We measured infant length, weight, and head circumference at birth, 42 days, 6 months, and 12 months. Linear mixed regression model was used to estimate the associations between PFAS concentrations and repeated measurements of infant growth. Effect modification by infant sex was estimated. ResultsElevated perfluoroheptanoic acid (PFHpA) concentration was negatively associated with infant length-for-age Z score (LAZ) (β = −0.06, 95% confidence interval (CI): −0.11, −0.01) during the first year. Adverse associations were also observed for perfluorobutane sulfonate (PFBS) and weight-for-length Z score (WFL) (β = −0.02, 95% CI: −0.04, −0.00) and BMI-for-age Z score (BAZ) (β = −0.02, 95% CI: −0.04, −0.00). However, perfluorododecanoic acid (PFDoA) was positively associated with WFL (β = 0.03, 95% CI: 0.00, 0.06) and BAZ (β = 0.03, 95% CI: 0.00, 0.06). The adverse association of PFHpA and LAZ was more pronounced among males (β = −0.06; 95% CI: −0.11, −0.00) than females (β = 0.06; 95% CI: 0.01, 0.12). ConclusionsIn our study, negative associations were found for maternal PFHpA exposure and infant LAZ, PFBS and WFL and BAZ. Meanwhile, maternal PFDoA exposure was positively related with WFL and BAZ. The adverse association of maternal PFHpA exposure and infant LAZ was more pronounced among males. The results should be interpreted with caution, further prospective cohort studies with longitudinal and detailed measures are warranted to confirm these findings.

Perfluoroalkyl Substances in the Western Tropical Atlantic Ocean.

The dispersion of perfluoroalkyl substances (PFAS) in surface and deep-water profiles (down to 5845 m deep) was evaluated through the Western Tropical Atlantic Ocean (TAO) between 15°N and 23°S. The sum concentrations for eight quantifiable PFAS (∑8PFAS) in surface waters ranged from 11 to 69 pg/L, which is lower than previously reported in the same area as well as in higher latitudes. Perfluoroalkyl carboxylic acids (PFCAs) were the predominant PFASs present in the Western TAO. The 16 surface samples showed variable PFAS distributions, with the predominance of perfluorooctanoic acid (PFOA) along the transect (67%; 11 ± 8 pg/L) and detection of perfluoroalkyl sulfonic acids (PFSAs) only in the Southern TAO. Perfluoroheptanoic acid (PFHpA) was often detected in the vertical profiles. PFAS distribution patterns (i.e., profiles and concentrations) varied with depth throughout the TAO latitudinal sectors (North, Equator, South Atlantic, and in the Brazilian coastal zone). Vertical profiles in coastal samples displayed decreasing PFAS concentrations with increasing depth, whereas offshore samples displayed higher PFAS detection frequencies in the intermediate water masses. Together with the surface currents and coastal upwelling, the origin of the water masses was an important factor in explaining PFAS concentrations and profiles in the TAO.

Exposure to perfluoroalkyl substances in early pregnancy and the risk of hypertensive disorders of pregnancy: A nested case-control study in Guangxi, China

BackgroundPrevious epidemiological studies have examined the associations between exposure to perfluoroalkyl substances (PFASs) and the risk of hypertensive disorders of pregnancy (HDP). However, these studies have drawn discrepant conclusions and have some limitations. MethodsA nested case-control study was conducted with the Guangxi Zhuang Birth Cohort (GZBC), a prospective, ongoing birth cohort that was implemented in Guangxi, China, in June 2015. Maternal serum concentrations of nine PFASs were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS). The associations between PFAS exposure and the risk of HDP were assessed using logistic regression (single-exposure), weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models. ResultsA total of 136 HDP cases and 408 controls were enrolled in this study. In logistic regression models, perfluoroundecanoic acid (PFUnA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluorobutanesulfonic acid (PFBS) were positively associated with HDP, while perfluorohexane sulfonate (PFHxS) was inversely associated with HDP. In the BKMR analysis, the joint effect of PFASs was positively associated with HDP. PFOS and PFBS showed positive trends, while PFHxS and PFHpA showed inverse trends. In WQS regression analysis, we calculated two WQS indices that were estimated using constraints in both the positive and negative directions of effects. Both WQS indices were significantly associated with HDP (OR: 2.663, 95% CI: 1.795–3.951; OR: 0.338, 95% CI: 0.229–0.499, respectively). PFBS, PFOS and PFUnA had significant weights in the positive effect direction; PFHxS, perfluoroheptanoic acid (PFHpA) and perfluorododecanoic acid (PFDoA) had significant weights in the negative effect direction. ConclusionConsidering all model results, we found that combined exposure to nine PFASs had a positive effect on the development of HDP. Moreover, PFOS and PFBS were positively associated with the HDP risk, while PFHxS and PFHpA were negatively associated with the HDP risk in women in Guangxi, China.

Perfluoroalkyl substances are linked to incident chronic spontaneous urticaria: A nested case-control study

Previous studies suggested immunotoxicity of perfluoroalkyl substances (PFASs), but contradictory findings were reported for the associations of PFASs with allergies. The current study aimed to investigate the association of serum PFASs with incident chronic spontaneous urticaria (CSU) in adults. A nested case-control study within a longitudinal cohort of 7051 government employees in China was conducted. Participants with urticaria at the baseline were excluded. During the first follow-up, 70 incident CSU cases were included, and 70 matched healthy controls were randomly selected. In serum samples collected at the baseline, eight PFASs were determined using the UHPLC-MS/MS approach. The median serum concentrations of perfluorobutanoic acid (PFBA) and perfluoroheptanoic acid (PFHpA) were significantly higher in participants with incident CSU. The area under the receiver operating characteristic curve was 0.714 (95% CI: 0.60–0.83) based on the joint prediction by PFBA and PFHpA. The Bayesian kernel machine regression showed a nonlinear positive overall effect of the mixture of PFASs, and identified significant single effects of PFBA and PFHpA. Serum interleukin-4 was significantly higher in the case group at baseline, and was positively associated with PFHpA (r = 0.24). Causal mediation analysis indicated interleukin-4 as a partial mediator (14.8%) in the association of PFHpA with CSU. In conclusion, serum PFASs are associated with an increased risk of incident CSU, and PFBA and PFHpA might be the effective compounds.

Esterification of perfluorinated carboxylic acids with bromomethyl aromatic compounds for gas chromatography combined with laser ionization mass spectrometry

Perfluorinated carboxylic acids (PFCAs) were derivatized with two types of aromatic compounds that contained a bromomethyl group, i.e., 2-(bromomethyl)naphthalene (BMN) and benzyl bromide (BB). The conditions for derivatization were optimized in terms of reaction temperature and time and the concentration of derivatizing reagent. Using these optimal conditions, the PFCAs-MN and PFCAs-B derivatives were measured by gas chromatography (GC) combined with mass spectrometry using an ultraviolet femtosecond laser (267 nm) as the ionization source. The efficiency of derivatization for PFCAs-B was higher than that for PFCAs-MN because of the smaller size of the chromophore (benzene). The ionization efficiency of PFCAs-MN, however, was better than PFCAs-B, since a larger sized chromophore (naphthalene) and then a larger molar absorptivity was preferable for resonance-enhanced two-photon ionization. Due to superior GC separation, BB was successfully used as the derivatizing agent for the trace analysis of PFCAs, with detection limits of 6.0, 8.4, and 9.5 ng/mL for perfluoroheptanoic, perfluorooctanoic, and perfluorononanoic acids, respectively. The other bromomethyl aromatic compounds were evaluated for use as a derivatization reagent in future studies.

Ultratrace analysis of per- and polyfluoroalkyl substances in drinking water using ice concentration linked with extractive stirrer and high performance liquid chromatography – tandem mass spectrometry

Detection of drinking water contaminants is vital to the protection of human health. One group of contaminants that have recently generated serious concerns over health risks are per- and polyfluoroalkyl substances (PFAS). These compounds are very bio-persistent, leading to their detection in all types of water sources, including drinking water. While analysis of drinking water for PFAS is important, it is currently arduous to detect ultratrace levels of these contaminants. Specifically, current ultratrace PFAS analysis methods are difficult, costly, require large sample volumes, and consume relatively large volumes of organic solvent. In the present work, an analytical method using Ice Concentration Linked with Extractive Stirrer (ICECLES) and high performance liquid chromatography—tandem quadrupole mass spectrometry (HPLC-MS/MS), was developed and validated to provide simple and ultratrace analysis of drinking water for 14 PFAS. The method featured a relatively low sample volume requirement (10 mL), automated extraction, minimal matrix effects, and minimal organic solvent use (i.e., the method requires only 50 µL of methanol per sample). The method produced a wide linear range of 0.5 to 500 ng/L, ultratrace limits of detection (0.05 to 0.3 ng/L), and good accuracy and precision (i.e., 87 to 108% accuracy and ≤19% relative standard deviation as a measure of precision). This method was tested on drinking water samples from across the United States and detected at least one PFAS compound in 52 of the 53 drinking water samples tested. Perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) were detected in 89, 96, and 77% of the samples tested with maximum concentrations of 268 ng/L for PFHxA, 213 ng/L for PFOA, and 75.7 ng/L for PFHpA. Additionally, perfluorononanoic acid, perfluorodecanoic acid, and perfluoroheptanoic acid were each detected in at least one drinking water sample at concentrations > 20 ng/L. The availability of the method presented here allows ultratrace detection of PFAS while circumventing many of the disadvantages of current methods.

Prenatal exposure to per- and polyfluoroalkyl substances and infancy/child growth trajectories through 2 years

BACKGROUND AND AIM: Prenatal exposure to poly- and per-fluoroalkyl substances (PFAS) has been associated with reduced birth weight, but also with excess adiposity and overweight in childhood. These mixed findings warrant investigation of relationships between prenatal PFAS exposure and dynamic offspring growth. This study aims to investigate the association between prenatal PFAS exposure and early life growth trajectories through 2 years. METHODS: In a prospective cohort of women and their children from Shanghai, China, we quantified seven PFAS congeners in pregnant women’s serum during the first trimester. Four anthropometric measures, including weight (n=1346), length/height (n=1140), weight-for-length (n=1134), and head circumference (HC, n=1082), were evaluated among children at birth (3 days), 42 days, 6 months, 12 months, and 24 months, and then standardized into z scores. Trajectory groups were identified using group-based trajectory modeling for each measure. Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for trajectory groups according to log2-transformed PFAS concentrations. RESULTS:Five trajectory groups were identified for each anthropometric measure, respectively. In each measure, the trajectory with a stable trend near the null z score was selected as the reference group. Prenatal exposure to PFAS was consistently associated with elevated odds for weight low-rising trajectory characterized by rapid increase from a low birth weight (e.g., perfluorohexane sulfonate (PFHxS): OR=1.54, 95% CI: 1.10-2.14) and length/height high-rising trajectory characterized by increase from a large value (e.g., perfluorononanoic acid (PFNA): OR=1.69, 95% CI: 1.05-2.73). Inverse associations were observed with HC high-stable trajectory characterized by large HC (e.g., perfluoroheptanoic acid (PFHpA): OR=0.75, 95% CI: 0.58-0.96) and HC low-stable trajectory characterized by small HC (e.g., PFHxS: OR=0.70, 95% CI: 0.50-1.00). No association was observed for weight-for-length trajectories. CONCLUSIONS:We observed associations between prenatal PFAS exposure and unusual growth trajectories in early life, suggesting enduring impact of prenatal PFAS exposure. KEYWORDS: PFAS, Birth outcomes, Endocrine disrupting chemicals, Multi-pollutant, Environmental epidemiology

Exposure to per- and polyfluoroalkyl substances (PFAS) through drinking water in Barcelona metropolitan area

BACKGROUND AND AIM: Per- and polyfluoroalkyl substances (PFAS) are a group of water-soluble chemicals of concern due to their persistence, widespread human exposure and associated adverse health outcomes across all life stages. Drinking water is one of the main routes of human exposure to PFAS. METHODS: We assessed 38 PFAS in 64 drinking water samples sourced from tap water (N=42, one per postal code), bottled (N=11), activated carbon (N=6) and reverse osmosis (N=5) filtered tap water in Barcelona, Spain. Liquid chromatography coupled tandem mass spectrometry was used to determine PFAS. Physico-chemical properties including residual chlorine, total organic carbon and conductivity were also measured. Water consumption habits of study participants (N=39) were collected through online questionnaires. RESULTS:The most abundant PFAS in unfiltered tap water were perfluoropentanoic acid (PFPeA) [3 ng/L (2.0-5.0)] -among 64% samples above the limit of quantification (LOQ)-, perfluorohexanoic acid (PFHxA) [14 ng/L (10-18)] -31%-, perfluoroheptanoic acid (PFHpA) [3 ng/L (2.25-4)] -52%-, perfluorooctanoic acid (PFOA) [11 ng/L (10-12)] -12%-, perfluorobutane sulfonic acid (PFBS) [9 ng/L (6.5-14.5)] -64%-, and perfluorooctane sulfonate (PFOS) [12.5 ng/L (10-14)] -52%-, with corresponding median (interquartile range, IQR). The median concentration of total PFAS was 29 ng/L (IQR=24-51), among 79% of tap water samples with PFAS LOQ. Individual PFAS displayed a range of positive correlations (Spearman, two-tailed) between r=0.36 (p=0.02) and r=0.67, (p0.001). Conductivity showed a geographical pattern linked to the tap water source, and a positive correlation (r=0.75, p0.001) with total PFAS. Reverse osmosis removed PFAS from tap water, while activated carbon filters did not. PFAS were not detected in bottled water. The mean consumption of water at home was 1.4L/day, and 0.8L/day outside of home. The main source of water was tap (43%) at home, and bottled or filtered (37.5% each) outside. CONCLUSIONS:Concentrations were below the EU Drinking Water Directive 2020/2184 PFAS Total parametric value (100 ng/L). KEYWORDS: PFAS, Exposure assessment, Chemical exposures, Water quality

Influence of Electrolyte Concentration on Single-Molecule Sensing of Perfluorocarboxylic Acids.

Perfluorocarboxylic acids (PFCAs) are an emerging class of persistent organic pollutants. During the fabrication process, it is unavoidable to form PFCA homologs or isomers which exhibit distinct occurrence, bioaccumulation, and toxicity. The precision measurement of PFCAs is therefore of significant importance. However, the existing characterization techniques, such as LC-MS/MS, cannot fully meet the requirement of isomer-specific analysis, largely due to the lack of authentic standards. Single-molecule sensors (SMSs) based on nanopore electrochemistry may be a feasible solution for PFCAs determination, thanks to their ultra-high spatiotemporal resolutions. Hence, as a first step, this work was to elucidate the influence of electrolyte concentration on the four most critical indicators of nanopore measurements, and furthermore, performance of nanopore SMSs. More specifically, three of the most representative short-chain PFCAs, perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA), were adopted as the target analytes, aerolysin nanopore was employed as the sensing interface, and 2, 3 and 4 M KCl solutions were used as electrolytes. It was found that, when the concentration of KCl solution increased from 2 to 4 M, the conductance of aerolysin nanopore increased almost linearly at a rate of 0.5 nS per molar KCl within the whole voltage range, the current blockade of PFPeA at −50 mV increased from 61.74 to 66.57% owing to the enhanced steric exclusion effect, the maximum dwell time was more than doubled from 14.5 to 31.5 ms, and the barrier limited capture rate increased by 8.3 times from 0.46 to 3.85 Hz. As a result, when using 4 M KCl as the electrolyte, over 90% of the PFPeA, PFHxA and PFHpA were accurately identified from a mixed sample, and the calculated limit of detection of PFPeA reached 320 nM, more than 24 times lower than in 2 M KCl. It was thus clear that tuning the electrolyte concentration was a simple but very effective approach to improve the performance of nanopore SMSs for PFCAs determination.

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.

A flow-through cell for the electrochemical oxidation of perfluoroalkyl substances in landfill leachates

A novel boron-doped diamond (BDD) flow-through cell was used to evaluate the electrochemical oxidation of perfluoroalkyl acids (PFAAs) in landfill leachates. Six different leachates with a concentration of individual PFAAs in the range of 102 − 104 ng/L were treated. The performance of the flow-through cell was assessed and compared with synthetic solutions for the oxidation of two representative PFAAs: perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Subsequently, the effect of current density and the variability of leachates composition was investigated for the electrochemical oxidation of PFAAs in real landfill leachates. Non-detect levels and >90% degradation was reached for PFOS and PFOA after 2 h of treatment for all leachates tested. Decreasing trends for perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), and perfluorohexanesulphonic acid (PFHxS), and increasing trends for perfluoropentanoic (PFPeA), perfluorobutanoic (PFBA), and perfluorobutanesulphonic acid (PFBS) were observed. The total PFAAs removal ranged from −138.6 to 73.5%. Correlations between the composition of the leachates and PFAAs removal percentages were determined. Overall, the results show the potential of electrochemical oxidation to oxidize PFAAs present in high strength water such as landfill leachates.

Temporal trends, 2000–2017, of perfluoroalkyl acid (PFAA) concentrations in serum of Swedish adolescents

Per- and polyfluoroalkyl substances (PFAS) have been extensively used as surfactants because of their high stability and good water/oil-repellent properties. PFASs, especially perfluoroalkyl acids (PFAAs), have long biological half-lives, and exposure may cause adverse health effects in humans. We assessed temporal trends of concentrations of eight PFAAs in serum of Swedish adolescents (age 16–21 years) from the general population, and estimated the stability of PFAAs and serum samples after 6 years of storage. Repeated cross-sectional sampling was performed on five occasions (covering in total 1213 individuals, 83% males) in southern Sweden between 2000 and 2017. We analyzed serum for perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluorododecanoic acid (PFDoDA) using liquid chromatography-tandem mass spectrometry. We assessed time trends using linear regression, long-term stability was assessed by reanalyzing samples collected 2013, and the comparison was done using Pearson correlation and Bland-Altman plots.PFHxS, PFOS, and PFOA decreased by 6.7% (CI: –7.0, –6.3%), 12.6% (CI: –12.9, –12.3%), and 6.5% (CI: –6.8, –6.1%) per year, respectively, and year of sampling explained 48–81% of the variation in concentrations. PFNA and PFDA seemed to increase up to 2009 and decrease thereafter. The trends were consistent after sensitivity analyses excluding women. Strong correlations of 94–97% were observed for concentrations of all compounds, except PFHxS, after storage. The observed trends closely followed the timing of manufacturers’ voluntary phase-out initiatives, and of regulatory measures governing the compounds implemented in the EU and USA. This indicates that these actions mitigated the population’s exposure to PFHxS, PFOS, and PFOA and, in recent years, to PFNA and PFDA, in southern Sweden. Furthermore, the results suggest that PFAAs remain stable in serum samples after long-term storage.

Toxicological Response of Chironomus dilutus in Single-Chemical and Binary Mixture Exposure Experiments with 6 Perfluoralkyl Substances.

Few studies have determined the toxicity of perfluoralkyl substances (PFAS) to aquatic invertebrates. We exposed Chironomus dilutus to 6 different PFAS to assess single-chemical toxicity and relative or proportional toxicity among substances. A 10-d range-finding test was conducted to inform 20-d assays for the following PFAS: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), and perfluoroheptanoic acid (PFHpA). A 20-d binary mixture study of PFOS+PFHxS followed the single-chemical tests. Measurement endpoints for 20-d tests included larval survival and biomass. Log-logistic concentration response models were used to estimate 10, 20, and 50% effect concentrations (EC20, EC50) for PFOS, PFHxS, and PFOA. Survival EC50s for PFOS, PFHxS, and PFOA were 2.49, 3860, and 192 000 µg/L, respectively, whereas survival EC20s were 1.70, 913, and 119 000 µg/L for PFOS, PFHxS, and PFOA, respectively. Biomass as a combined survival and growth endpoint resulted in EC20s of 1.89, 896, and 137 000 µg/L for PFOS, PFHxS, and PFOA, respectively. Maximum concentrations tested (no-observed-effect concentrations) for PFNA, PFBS, and PFHpA were 2 to 3 orders of magnitude greater than the PFOS EC50s and showed no toxicity to C. dilutus, even at exposure concentrations well above what would be considered environmentally relevant. The binary mixture of 2.5 µg/L PFOS+1000 µg/L PFHxS showed reduced survival compared to controls and some indication of potential additive or synergistic interaction between PFOS and PFHxS. Overall, the present study supports previous studies showing PFOS to be the most toxic PFAS to aquatic life and suggests that PFOS could be more toxic to the freshwater midge than previously reported.Environ Toxicol Chem 2021;40:2319-2333. © 2021 SETAC.

Uptake, Tissue Distribution, and Elimination of 8:2 Polyfluoroalkyl Phosphate Diesters in Mytilus galloprovincialis.

Although the distribution of 8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) in aquatic environments has been reported, details on its uptake, tissue specificity, and elimination in bivalve mollusks remain to be clarified. The present study is the first report on the accumulation and elimination of 8:2 diPAP in mussels (Mytilus galloprovincialis). The tissue-specific accumulation and depuration of 8:2 diPAP and its metabolites were investigated via semistatic seawater exposure (8:2 diPAP at a nominal concentration of 10 μg/L), through water-borne exposure with static daily renewal over a 72-h exposure period and a 360-h depuration period. The digestive gland was found to be the target organ where accumulation and biotransformation primarily occur. The bioaccumulation factor values (mL/g dry wt) in different organs were in the following order: digestive gland (1249) > adductor muscle (315) > gills (289) > gonad (82.9) > mantle (33.0). Moreover, the distribution of 8:2 diPAP among tissues may be related to the total protein content. The 8:2 diPAP tended to be excreted in feces. The compounds 8:2 fluorotelomer carboxylic acid, 8:2 fluorotelomer unsaturated carboxylic acid, 7:3 fluorotelomer carboxylic acid, perfluorooctanoic acid, and perfluoroheptanoic acid were detected and quantified as phase I metabolites, and the concentration of all phase I metabolites relative to the 8:2 diPAP concentration (72 h) was 0.304 mol%. A phase II metabolite, 8:2 fluorotelomer alcohol conjugated with sulfate, was detected but not quantitated in the digestive gland. A biotransformation pathway of 8:2 diPAP in M. galloprovincialis was proposed on the basis of the results obtained in the present study and previous studies. These findings improve our understanding of the accumulation of perfluorocarboxylic acids in bivalve mollusks.Environ Toxicol Chem 2021;40:1992-2004. © 2021 SETAC.

Occurrence and Ecological Risk Assessment of Perfluoroalkyl Substances (PFASs) in Water and Sediment from an Urban River in South China.

The chemical substances in urban rivers influence municipal water systems and reflect the recent use of these chemicals by humans or industries around the urban center. In this study, seven perfluoroalkyl substances (PFASs)-perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), 2-perfluorohexyl ethanol (6:2 FTOH), 2-perfluorooctyl ethanol (8:2 FTOH), and 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (F-53B)-could be detected and quantified in river water and sediment samples collected from one tributary of the Liuxi River, which is part of Pearl River near Guangzhou in Guangdong province, South China. The fluxes of target PFASs into Liuxi River and their related ecological risks were further estimated. The total concentrations of PFASs (ΣPFASs) ranged from 506 to 3.16 × 103ng/L in water samples and 9.13 to 850ng/L in sediment samples. The two dominant PFAS compounds were 6:2 FTOH and PFHpA, which accounted for more than 90.0% of ΣPFASs in river water and sediment. Correlation analysis showed that there was significant positive correlation (p < 0.01) between two selected PFASs (e.g., between 6:2 FTOH and PFHpA). Correlation analysis of PFASs in river water and sediment indicated most PFASs in sediment were partitioned from river water. The ecological risk assessment indicated that the detected PFASs have a low risk (HQ < 0.1) in river water and sediment to Daphnia magna in the Liuxi River.

Assessment of exposure to perfluoroalkyl substances (PFASs) in dogs by fur analysis

Poly- and perfluoroalkyl substances (PFASs) are a large group of chemicals commonly used in various branches of industry, which may adversely affect the living organisms.The aim of this study were to evaluate exposure of dogs to six selected PFASs: five perfluoroalkyl carboxylic acids (perfluorobutanoic acid - PFBuA, perfluoropentanoic acid - PFPeA, perfluorohexanoic acid - PFHxA, perfluoroheptanoic acid - PFHpA, perfluorooctanoic acid – PFOA) and perfluorooctane sulfonic acid (PFOS) through the analysis of fur samples. To our knowledge this is the first study concerning the use of fur samples to evaluation of exposure of domestic animals to PFASs. Relationship between PFASs concentration and age, gender and body weight of animals was also evaluated. Fur samples were collected from 30 dogs living in Olsztyn (Poland). All PFASs studied were detected in the canine fur samples.The highest concentrations were observed in the case of PFOA and PFBuA, detected at concentrations in the range between 1.51 and 66.7 ng/g and 0.98–26.6 ng/g, respectively. During the present study generally no statistically significant differences dependent on gender, age and body weight of animals were found.This study confirms the suitability of fur samples for biomonitoring of exposure to PFASs in domestic animals, what may be important in veterinary toxicology.

Planktonic microbial responses to perfluorinated compound (PFC) pollution: Integrating PFC distributions with community coalescence and metabolism

The presence of perfluorinated compound (PFC) contamination in riverine ecosystems represents a novel challenge for environmental remediation. However, little attention has been paid to how PFCs affect planktonic microbial community coalescence. Here, the spatial profiles of fourteen PFCs and their contributions to community assembly were determined using field sampling in a natural river confluence. Overall, PFPeA (perfluorovaleric acid), PFBS (perfluorobutylsulfonate), PFHpA (perfluoroheptanoic acid) and PFHxA (perfluorohexanoic acid) were identified as important indicators of PFC pollution, accounting for the majority of the spatial heterogeneity in PFC pollution. PFPeA (perfluorovaleric acid) (9.39%) and PFTrDA (perfluorotridecanoate acid) (8.61%) contributed more to microbial taxonomic spatial heterogeneity than did other factors, such as pH, dissolved oxygen and velocity. PFOA (pentadecafluorooctanoic acid) (R2 = 0.353) and PFBS (R2 = 0.297) drove turnover in archaeal communities within river sections (transversely), while PFHpA (R2 = 0.251) and PFOS (perfluorooctane sulphonate) (R2 = 0.105) drove turnover in bacterial communities transversely and longitudinally, respectively. Phylogenetic null modeling suggested that archaeal (68.89–83.33%) community assembly was dominated by stochastic processes, and was balanced by PFHxA (R2 = 0.349) and PFOA (R2 = 0.290). Furthermore, PFOS inhibited the biosynthesis of several key amino acids in archaea, and PFBA enhanced the potential for bacterial infections in humans (p < 0.05), threatening water quality. In sum, this study provides new insights into riverine ecological risk management.

Environmental exposure to perfluoroalkyl substances in early pregnancy, maternal glucose homeostasis and the risk of gestational diabetes: A prospective cohort study.

Humans are widely exposed to environmental perfluoroalkyl substances (PFAS), which may affect glucose homeostasis. However, research linking PFAS exposure to glucose homeostasis during pregnancy is limited and the results were inconsistent. We aimed to investigate the association between PFAS exposure and glucose homeostasis in pregnancy in a large prospective cohort. A total of 2747 pregnant women who participated in the Shanghai Birth Cohort, had blood samples in early pregnancy and completed a 75g oral glucose tolerance test (OGTT) at 24-28 gestational weeks were included. 10 PFAS were determined by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS-MS) in the plasma samples in early pregnancy. Logistic regression was used to explore the associations between PFAS concentrations and gestational diabetes mellitus (GDM), while multiple linear regression was used to model the associations between PFAS and OGTT fasting, 1-h and 2-h glucose levels. Potential confounders were adjusted. Bayesian kernel machine regression (BKMR) and a quantile-based g-computation approach (qgcomp) were employed to explore the joint and independent effects of PFAS on glucose homeostasis. The incidence of GDM was 11.8%. One log-unit increment in plasma concentrations in early pregnancy was associated with an increased risk of GDM for perfluorobutane sulfonate (PFBS) (adjusted odd ratio (aOR)=1.23, 95% confidence interval (95% CI): 1.05, 1.44) and perfluoroheptanoic acid (PFHpA) (aOR=1.25, 95% CI: 1.07, 1.46). Perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexanesulfonate (PFHxS) and PFHpA were positively correlated with 1-h and 2-h glucose levels. Results of the mixed exposure model showed that the joint effects of PFAS were significantly associated with abnormal glucose homeostasis; In the BKMR model, PFAS mixture exposure was positively associated with the GDM incidence, 1-h and 2-h glucose levels and negatively correlated with FBG level. A similar trend could be observed in qgcomp and the positive correlation between PFAS and 2-h glucose level was significant (β=0.12, 95% CI: 0.04, 0.20). PFOS, PFNA and PFHpA may be the main contributors after controlling for other PFAS congeners. PFOS was significantly correlated with GDM incidence and 2-h glucose level, and PFHpA was significantly associated with FBG and 2-h glucose levels. The above associations were more prominent among women with a normal prepregnant BMI. Environmental exposure to PFAS may affect glucose homeostasis in pregnancy and increase the risk of GDM, especially in normal weight women.

Occurrence of per- and polyfluoroalkyl substances (PFASs) in wastewater of major cities across China in 2014 and 2016

China produced and consumed a large amount of per- and polyfluoroalkyl substances (PFASs). whose persistency and possible toxicity to organisms have raised public health concerns. Analyzing influent wastewater could help to assess the composition and mass load of PFASs discharged into a wastewater treatment plant (WWTP) from its catchment. In this study, we analyzed 27 PFASs in wastewater samples collected from 42 WWTPs across China in 2014 and 2016. Results indicated that perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were the most common PFASs in wastewater. Population normalized mass loads of PFOA and PFOS were higher in Eastern China than in the other three regions, possibly due to their higher usage. Although the concentrations of PFASs in Central and West areas were showed lower than in East area, Wuhan (in Central area) and Lanzhou (in West area) were hotspots of PFASs pollution because of their industry structure. Population density and per capita Gross Domestic Product (GDP) have positive correlations with the concentration of PFBA, PFOA, PFHxA, and ∑PFASs in wastewater. The estimated annual release of PFASs to WWTPs in our study is much lower than the total emission to the environment. Our results suggest that although there was some reduction in the production volume, certain legacy PFASs were still released into wastewater and their composition and concentration vary among WWTPs.

Mechanisms for tissue-specific accumulation and phase I/II transformation of 6:2 fluorotelomer phosphate diester in earthworm (M. guillelmi)

Polyfluoroalkyl phosphate esters (PAPs) are high production volume surfactants used in the food contact paper and packaging industries. They are prone to partition to soil due to their strong hydrophobicity and may biotransform into recalcitrant perfluoroalkyl carboxylic acids (PFCAs); little is known about their fate and behaviors in terrestrial organisms. Here, geophagous earthworms (M. guillelmi) were exposed to 6:2 fluorotelomer phosphate diester (6:2 diPAP)-contaminated soil to examine tissue-specific accumulation and biotransformation. 6:2 diPAP quickly accumulated in M. guillelmi with the highest biota-soil-accumulation factor (BSAF) in the gut, followed by the organs, skin, and body fluid. The total amount of 6:2 diPAP accumulated in the skin was the highest due to its high mass content. These results indicated that skin absorption and gut processes were two major pathways for earthworms to accumulate 6:2 diPAP from soil. In vitro desorption experiments indicated that the gut digestion fluid greatly promoted the desorption of 6:2 diPAP from the soil and enhanced its bioavailability. Degradation of 6:2 diPAP in the soil was stimulated when the earthworm appeared. In contrast to the soil, a more extensive transformation occurred in the earthworm. Perfluorohexanoic acid (PFHxA) was the primary phase Ⅰ product, followed by perfluoropentyl propanoic acid (FPePA), perfluoropentanoic acid (PFPeA), 2-perfluorohexyl ethanoic acid (FHEA), and perfluoroheptanoic acid (PFHpA), which confirmed the occurrence of α- and β-oxidation in earthworms. For the first time, a new phase II product, namely, a 6:2 fluorotelomer alcohol sulfate conjugate, was identified in earthworms at unexpectedly high levels, which might be the primary way earthworms eliminate 6:2 diPAP. Both in vivo and in vitro experiments suggested that 6:2 diPAP experienced faster and more extensive biotransformation in the gut than in the organs. This work sheds light on the bioaccumulation and biotransformation of 6:2 diPAP in terrestrial invertebrates, providing strong evidence of indirect sources of PFCAs in the environment.