Data on isomer-specific transplacental transfer of perfluoroalkyl substances (PFASs) are very scarce. This study investigates transplacental transfer of 23 PFASs, including isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), by analyzing 63 paired maternal and cord whole blood samples collected in Hubei, China. Significant correlations (r = 0.311–0.888; p ≤ 0.013) were observed between the concentrations in maternal and cord blood for most PFASs, indicating that PFASs could be efficiently transported from mother to fetus. For perfluorocarboxylates, a U-shaped trend of transplacental transfer efficiencies (TTEs) with increasing carbon chain lengths was confirmed. For PFOA and PFOS branched isomers, TTEs generally increased as the branching point moved closer to the carboxyl or sulfonate moiety, and branched isomers transferred more efficiently than their linear isomers did. This is the first report of the TTEs of PFAS isomers based on human whole blood samples and the first calculation of the TTEs of perfluorooctane sulfonamide. For almost all PFASs, the TTEs we reported are lower than those from previous studies based on serum or plasma. Whole blood is recommended for risk assessment of PFAS placental transfer considering that PFASs exhibit different partitioning behaviors between blood matrices. More accurate parameters for the health risks of PFASs during prenatal exposure are provided here.

The occurrence, toxicities, and ecological risks of five heavy metals (Pb, Cu, Cd, Zn and Ni) in the sediment of Taihu Lake were investigated in this study. To evaluate the toxicities caused by the heavy metals, the toxicities induced by organic contaminants and ammonia in the sediments were screened out with activated carbon and zeolite. The toxicities of heavy metals in sediments were tested with benthic invertebrates (tubificid and chironomid). The correlations between toxicity of sediment and the sediment quality guidelines (SQGs) derived previously were evaluated. There were significant correlations (p < 0.0001) between the observed toxicities and the total risk quotients of the heavy metals based on SQGs, indicating that threshold effect level (TEL) and probable effect level (PEL) were reliable to predict the toxicities of heavy metals in the sediments of Taihu Lake. By contrast, the method based on acid volatile sulfides (AVS) and simultaneously extracted metals (SEM), such as ∑SEM/AVS and ∑SEM-AVS, did not show correlations with the toxicities. Moreover, the predictive ability of SQGs was confirmed by a total predicting accuracy of 77%. Ecological risk assessment based on TELs and PELs showed that the contaminations of Pb, Cu, Cd and Zn in the sediments of Taihu Lake were at relatively low or medium levels. The risks caused by heavy metals in the sediments of northern bay of the lake, which received more wastewater discharge from upper stream, were higher than other area of the lake.Download high-res image (225KB)Download full-size image

•Humic acid was fractioned to three fractions according to polarities.•All the fractions promoted nano-TiO2 photocatalytic performance in different degrees.•Charge-transfer complex was formed between humic acid fractions and nano-TiO2.•The fractions promoted .OHs production and thus nano-TiO2 photocatalytic capacity.•The carboxylic group displayed more significant effect than phenolic hydroxyl group.Large volume production and application of nano-TiO2 make it inevitably release to natural waters and its environmental behaviors would be affected by natural organic matters. In this study, the mechanisms of humic acid (HA) affecting the photocatalytic performance of nano-TiO2 were elucidated by using three HA fractions from the same source but with different polarities. Bulk HA was fractionated on a silica gel column to get three fractions with polarity increasing in the order of FA, FB and FC. FA was fulvic acid-like while FB and FC were humic acid-like. All the three fractions (at 0.1 mg/L) promoted the generation of hydroxyl radicals (OHs) by nano-TiO2, and thus in turn facilitated the photocatalytic degradation of bispheol A (BPA). FA and FC displayed a stronger promotion effect than FB and the bulk HA. Online in situ flow cell ATR-FTIR and XPS analyses indicated that HA fractions could form charge-transfer complex with nano-TiO2 surface through the phenolic hydroxyl and carboxylic groups, which favored the separation of photogenerated electron-hole pairs. Through step methylation experiments, it was verified that the phenolic hydroxyl and carboxylic groups of HA fractions played important roles in promoting the photocatalytic performance of nano-TiO2, and the effect of carboxylic group was more significant than the phenolic hydroxyl group.Download high-res image (223KB)Download full-size image

•Novel I-deficient BiOI thin films were solvothermally synthesized assisted with calcination.•BiOI nanospheres grew on glass plate via BiOSi bonds and thin film was formed.•Iodine vacancies formed during calcination, leading to enhanced photoelectric property.•The film exhibited distinct photocatalytic activity under simulated sunlight.•The film was very durable and kept high activity after 6 runs of reaction.I-deficient BiOI thin film was prepared via a facile solvothermal approach assisted with a ([C6Mim]I) ionic liquid and calcination. The glass plates were pretreated with high pressurized water to make the substrate surface rough. A thin layer of BiOI grew stably on the rough surface of glass substrate with uniformly assembled nanosheets. As the preparation process repeated, BiOI crystals continued to grow and the film became denser and thicker with larger surface area and pore volume. During calcination, a small portion of iodine was lost and iodine vacancies formed, leading to I-deficient BiOI. The produced iodine vacancies acted as traps for photogenerated holes. Consequently, the recombination of photogenerated electrons and holes were significantly inhibited. The film displayed an excellent photoelectric property and distinct photocatalytic degradation efficiency for bisphenol A (BPA), a typical endocrine disrupting compound (EDC), under simulated sunlight. The film also displayed very good durability and reusability. Without necessity to separate the photocatalysts from reaction solution, the as-prepared I-deficient BiOI thin film displayed a great potential for practical wastewater treatment.Download high-res image (156KB)Download full-size image

As one of the most popular carbon-based nanomaterials, graphene oxide (GO) has the potential to be released in aquatic environment and interact with some coexistent organic pollutants, such as perfluorooctanesulfonate (PFOS), which is an emerging persistent organic pollutant. In this study, the adsorption of PFOS on GO in the presence of fulvic acid (FA), the impacts of GO and FA on PFOS toxicokinetics in carp (Cyprinus carpio), and in vitro digestion behaviors were examined. The results indicated that PFOS could be strongly adsorbed on GO with a Freundlich affinity coefficient KF of 580 ± 205 (mg/g)/(mg/L)n, while the adsorption was suppressed by FA due to competitive adsorption. GO significantly enhanced the bioaccumulation of PFOS in blood, kidney, liver, gill, intestine, and muscle of carp, and the corresponding bioaccumulation factor (BAF) was in the range of 2026–53513 L/kg. The enhancement was greatest for liver and intestine, which was 10.3 and 9.33 times of that without GO, respectively. In vivo toxicokinetic and in vitro digestion–absorption experiments indicated that GO could carry PFOS to penetrate the intestine cells. There herein, PFOS absorption, especially via intestine, and the uptake rate coefficient (ku) were greatly enhanced, leading to distinctly promoted bioaccumulation of PFOS in fish. However, FA could facilitate the flocculation of GO in the intestine and also accelerate excretion of GO–PFOS complex. Thus, in the presence of FA, PFOS absorption was reduced and the promotion effect of GO on PFOS accumulation was remitted.

Perfluoroalkyl substances (PFASs) such as perfluorohexanesulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and PFOS–precursors are routinely measured in human plasma and serum, but their relative abundance in the blood cell fraction has not been carefully examined, particularly at the isomer–specific level. Human plasma and whole blood were collected and partitioning behaviors of PFASs and their isomers between plasma and blood cells were investigated. In human samples, mass fraction in plasma (Fp) for PFASs increased among perfluoroalkyl carboxylates as the carbon chain length increased from C6 (mean 0.24) to C11 (0.87), indicating preference for the plasma fraction with increasing chain length. However, among perfluoroalkyl sulfonates, PFHxS (mean 0.87) had a slightly higher Fp than PFOS (0.85). In vitro assays with spiked Sprague–Dawley rat blood were also conducted, and the results showed that PFOS–precursors had lower Fp values than perfluoroalkyl acids, with perfluoroctanesulfonamide having the lowest Fp (mean 0.24). Consistently, linear isomers of PFOS and PFOS–precursors had lower mean Fp than their corresponding total branched isomers. Multiplying by a factor of 2 is not a reasonable method to convert from whole blood to plasma PFAS concentrations, and current ratios could be used as more accurate conversion factors.

Bi2WO6 was synthesized with a hydrothermal method at different pHs and used for the degradation of tetracycline (TC) in water. The mesoporous Bi2WO6 prepared at pH 1 (BWO-1) displayed the highest adsorption and degradation capacity to TC due to its large surface area and more efficient capacity to separate photogenerated electrons and holes. 97% of TC at 20 mg·L−1 was removed by BWO-1 at 0.5 g·L−1 after 120 min irradiation under simulated solar light. Only 31% of the total organic carbon (TOC) was removed after 360 min irradiation although the TC removal reached 100%, suggesting that TC was mainly transformed to intermediate products rather than completely mineralized. The intermediates were identified by high-performance liquid chromatography-time of flight-mass spectrometry (HPLC-TOF-MS) and possible photodegradation pathways were proposed.

Silver nanowires (AgNWs) are being widely utilized in an increasing number of consumer products, which could release silver to aquatic environments during the use or washing process, and have received growing concerns on their potential risks to bio-organisms and humans. The present study demonstrated that AgNWs mainly experienced direct oxysulfidation by reacting with dissolved sulfide species (initial S2– concentration at 1.6 mg/L) to produce silver sulfide nanostructures under environmentally relevant conditions. Granular Ag2S nanoparticles were formed on the surface of the nanowires. The sulfidation rate constant (kAg) of AgNWs was compared with those of silver nanoparticles (AgNPs) at different particle sizes. It was found that the kAg positively correlated with the specific surface areas of the silver nanomaterials. Natural organic matter (NOM) suppressed the sulfidation of AgNWs to different extents depending on its concentration. Divalent cations (Mg2+ and Ca2+ ions) substantially accelerated the sulfidation rates of AgNWs compared to monovalent cations (Na+ and K+ ions). At the same ionic strengths, Ca2+ ions displayed the highest promoting effect among the four metallic ions.

Biotransformation of PFOS-precursors (PreFOS) may contribute significantly to the level of perfluorooctanesulfonate (PFOS) in the environment. Perfluorooctane sulfonamide (PFOSA) is one of the major intermediates of higher molecular weight PreFOS. Its further degradation to PFOS could be isomer specific and thereby explain unexpected high percentages of branched (Br-) PFOS isomers observed in wildlife. In this study, isomeric degradation of PFOSA was concomitantly investigated by in vivo and in vitro tests using common carp as an animal model. In the in vivo tests branched isomers of PFOSA and PFOS were eliminated faster than the corresponding linear (n-) isomers, leading to enrichment of n-PFOSA in the fish. In contrast, Br-PFOS was enriched in the fish, suggesting that Br-PFOSA isomers were preferentially metabolized to Br-PFOS over n-PFOSA. This was confirmed by the in vitro test. The exception was 1m-PFOSA, which could be the most difficult to be metabolized due to its α-branched structure, resulting in the deficiency of 1m-PFOS in the fish. The in vitro tests indicated that the metabolism mainly took place in the fish liver instead of its kidney, and it was mainly a Phase I reaction. The results may help to explain the special PFOS isomer profile observed in wildlife.

Despite that China is the largest global manufacturer of perfluoroalkyl substances (PFASs), the manufacturing methods and isomer purity of these chemicals are generally unknown. Here, sampling was conducted around a major fluorochemical manufacturing park in China in 2012, including soil and water collection inside the park, including from a wastewater treatment plant (WWTP), as well as in surrounding rivers and soil (∼15 km radius). Perfluoroalkyl sulfonates (PFSAs) were lower than perfluoroalkyl carboxylates (PFCAs) in all samples, and short-chain (C4–C6) PFCAs were predominant. Perfluoroalkyl phosphonates and phosphate diesters were occasionally detected, but at low detection frequency. Branched isomers of perfluorobutanesulfonate (PFBS) are reported for the first time, accounting for 15–27% of total PFBS in water. An enrichment of isopropyl-PFOA (28%) was found in WWTP influent, suggesting its manufacturing primarily by isopropyl telomerization. More numerous branched isomers were observed for the longer C9–C13 PFCAs (e.g., C12 PFCA had 16 branched isomers), including high proportions of one major branched isomer (likely isopropyl), possibly as impurities from isopropyl-PFOA manufacturing. Overall, short-chain perfluorinated acids were the predominant PFASs being released, but PFOA was still a major chemical in use at this site, primarily from isopropyl telomerization.

A novel organic–inorganic three-dimensional (3D) mesoporous graphite carbon nitride/BiOI (MCN/BiOI) heterojunction photocatalyst with excellent visible-light-driven photocatalytic performance was synthesized by a facile solvothermal method and used for degradation of bisphenol A (BPA) in water. After hybridization with MCN, a heterojunction was formed and the photogenerated carriers could be effectively separated by the internal electric field built at the heterojunction interface. The photocatalytic and photoelectrochemical performance of BiOI were improved and much higher than pure BiOI and MCN. The best photocatalytic performance was achieved with MCN proportion of 10%, and the kobs was approximately 1.6 times of pure BiOI and 3.4 times of MCN under simulated solar light irradiation, respectively. The photocurrent intensity generated by 10%-MCN/BiOI electrode was about 1.5 and 2.0 times of those induced by BiOI and MCN under visible-light irradiation, respectively. The superoxide radical species were predominant in the reaction system.Keywords: n-type MCN/p-type BiOI heterojunction; organic−inorganic hybrid photocatalyst; photocatalysis mechanism;

Biomagnification of perfluoroalkyl substances (PFASs) are well studied in marine food webs, but related information in fresh water ecosystem and knowledge on fractionation of their isomers along the food web are limited. The distribution, bioaccumulation, magnification, and isomer fractionation of PFASs were investigated in a food web of Taihu Lake, China. Perfluorooctanesulfonate (PFOS) and perfluorocarboxylates (PFCAs) with longer carbon chain lengths, such as perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnA), were predominant in organisms, while perfluorohexanoate (PFHxA) and perfluorooctanoate (∑PFOA) contributed more in the water phase. The consistent profile signature of PFOA isomers in water phase with 3M electrochemical fluorination (ECF) products suggests that ECF production of PFOA still exists in China. Linear proportions of PFOA, PFOS and perfluorooctane sulfonamide (PFOSA) in the biota were in the range of 91.9–100%, 78.6–95.5%, and 72.2–95.5%, respectively, indicating preferential bioaccumulation of linear isomers in biota. Trophic magnification factors (TMFs) were estimated for PFDA (2.43), perfluorododecanoate (PFDoA) (2.68) and PFOS (3.46) when all biota were included, suggesting that PFOS and long-chained PFCAs are biomagnified in the fresh water food web. The TMF of PFOS isomers descended in the order: n-PFOS (3.86) > 3+5m-PFOS (3.35) > 4m-PFOS (3.32) > 1m-PFOS (2.92) > m2-PFOS (2.67) > iso-PFOS (2.59), which is roughly identical to their elution order on a FluoroSep-RP Octyl column, suggesting that hydrophobicity may be an important contributor for isomer discrimination in biota.

Perfluoroalkyl acids (PFAAs) are persistent and bioaccumulative compounds that have been associated with adverse health outcomes. In human blood, PFAAs exist as both linear and branched isomers, yet for most linear homologues, and for all branched isomers, elimination rates are unknown. Paired blood and urine samples (n = 86) were collected from adults in China. They were analyzed by a sensitive isomer-specific method that permitted the detection of many PFAAs in human urine for the first time. For all PFAAs except perfluoroundecanoate (PFUnA), levels in urine correlated positively with levels in blood. Perfluoroalkyl carboxylates (PFCAs) were excreted more efficiently than perfluoroalkane sulfonates (PFSAs) of the same carbon chain-length. In general, shorter PFCAs were excreted more efficiently than longer ones, but for PFSAs, perfluorooctanesulfonate (PFOS, a C8 compound) was excreted more efficiently than perfluorohexanesulfonate (PFHxS, a C6 compound). Among PFOS and perfluorooctanoate (PFOA) isomers, major branched isomers were more efficiently excreted than the corresponding linear isomer. A one-compartment model was used to estimate the biological elimination half-lives of PFAAs. Among all PFAAs, the estimated arithmetic mean elimination half-lives ranged from 0.5 ± 0.1 years (for one branched PFOA isomer, 5m-PFOA) to 90 ± 11 years (for one branched PFOS isomer, 1m-PFOS). Urinary excretion was the major elimination route for short PFCAs (C ≤ 8), but for longer PFCAs, PFOS and PFHxS, other routes of excretion likely contribute to overall elimination. Urinary concentrations are good biomarkers of the internal dose, and this less invasive strategy can therefore be used in future epidemiological and biomonitoring studies. The very long half-lives of long-chain PFCAs, PFHxS, and PFOS isomers in humans stress the importance of global and domestic exposure mitigation strategies.

Microcystin-RR (MC-RR) is one of the most common cyanotoxin microcystins in fresh water and is of great concern due to its potential hepatotoxicity. In the present study, Bi2WO6 was synthesized with a hydrothermal method by varying the pH of the reaction solution in the range of 1–11. The surface area of the catalysts decreased, but the crystallinity and crystal size increased with the pH. The adsorption and degradation capacities of the catalysts decreased with increasing the preparation solution pH. The Bi2WO6 prepared at pH 1 (Bi2WO6-pH1) displayed the highest adsorption and degradation capacity to MC-RR even though it consisted of randomly aggregated particles. Nearly 100% of MC-RR at 10 mg L–1 was removed after 30 min of irradiation of near-ultraviolet light (300–400 nm) in a solution with Bi2WO6 concentration of 0.2 g L–1. The photodegradation efficiency of Bi2WO6-pH1 was greater in acid medium than in basic solutions. Several intermediate products were observed and identified by liquid chromatography/mass spectrometry/mass spectrometry, and a unique photodegradation pathway was proposed. It was assumed that a photo-Kolbe process happened at the site carboxyl acid group of the d-Glu residue by the photogenerated holes, producing a hydroperoxyl product at m/z 513.8. This intermediate could be further decomposed to an alcohol product at m/z 505.8 and a ketone product at m/z 504.8. The aromatic ring and diene bond of the Adda chain could also be attacked by the holes and form phenol and diol products.

Microcosms were built up to simulate a pond system with polybrominated diphenyl ether (PBDE) contaminated sediment and bioorganisms. The microcosms were divided into groups A and B. In group A, both benthic invertebrates (tubificid worms) and carp (Cyprinu carpio) were added, while in group B, only fish were added. After exposure for 20 d, the fish were sampled (exposure I). A net was fixed in the microcosms, and new fish were added (exposure II). These fish were prohibited from contacting the sediment by the net, and the accumulation and depuration of PBDEs in the fish were investigated. Among 11 monitored PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, BDE-206, BDE-207, BDE-208, and BDE-209), only 5 congeners (BDE-28, BDE-47, BDE-100, BDE-153, and BDE-154) were detected in the carp fillets and liver. BDE-99 and BDE-183 were not detected in the fish because of the efficient metabolic debromination in carp tissues. The uptake of PBDEs in exposure I was significantly higher/faster than that in exposure II, since the fish in exposure I had an opportunity to take in more of the highly contaminated particles. The uptake kinetics (ks) and elimination (ke) rate coefficients showed a general trend of decreasing with increasing log Kow. No significant difference was observed in uptake/depuration kinetics between groups A and B, indicating that the tubificids’ reworking does not affect the bioaccumulation of sediment-associated PBDEs in fish significantly. All the PBDE congeners, including nona- and deca-BDEs, were bioaccumulated in the tubificid worms. The PBDE concentrations in the worms were significantly higher than those in the fish, and the congener profile of the sevem major congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) was distinctly different from that of fish tissues. The biota–sediment accumulation factors in the worms ranged from 0.01 to 5.89 and declined with increasing bromination and log Kow.

Bismuth tungstate (Bi2WO6) catalysts of different morphology were synthesized with a hydrothermal method by controlling the pH of the reaction solution. The properties of the synthesized catalysts were characterized and all catalysts presented high photoabsorption capacity in the range of UV light to visible light around 450 nm. The surface area of the catalysts decreased but the crystallinity increased with the pH of the hydrothermal reaction solution in the range of 4−11. It was found that the crystallinity of the catalysts played an important role on their degradation capacity to Bisphenol A (BPA). Bi2WO6 catalyst prepared at pH 11 displayed a mesoporous structure and it showed the highest photocatalytic activity to degrade BPA under simulated solar light irradiation. Nearly 100% of BPA with original concentration at 20 ppm was removed after 30 min irradiation in a solution with pH 10 and Bi2WO6 amount of 1.0 g L−1. Furthermore, 86.6 and 99.1% of the total organic carbon was eliminated after 60 and 120 min irradiation, respectively. Only one intermediate at m/z 133 was observed by LC/MS and a simple pathway of BPA degradation by Bi2WO6 was proposed.

Bioaccumulation of penta-BDE (DE-71) in earthworms (Eisenia fetida) and the induced toxicities on the growth and reproduction of earthworms were investigated. All the major congeners in DE-71 could be bioaccumulated in earthworms and the concentration found in earthworms correlated to the spiked concentration in soil. DE-71 might inhibit the growth and reproduction of cocoons and juveniles of earthworms. The toxicities were dose dependent and increased with exposure time. Exposing earthworms to combination of DE-71 and Cd resulted in enhanced mortality and reduction of cocoons or juveniles in a synergistic mode. The presence of DE-71 may affect the relocation of Cd in earthworms. When the earthworms were exposed to Cd alone, Cd up-taken by earthworms was mainly partitioned in the cytosolic fraction. While DE-71 was present, Cd in the cytosolic fraction decreased significantly. It is perhaps that DE-71 inhibits the synthesis of matallothioneins, and then reduces the detoxification ability of earthworms. This is the first report about the toxicity of PBDEs to earthworms. The result would be useful for ecological risk assessment of PBDEs in terrestrial ecosystem.

In 2006, 128 serum samples were collected from three populations in Tianjin, China: office cleaners, university students, and policemen. These samples were all analyzed for polybrominated diphenyl ethers (PBDEs) and for other brominated flame retardants (BFRs). The median concentration of total PBDEs (sum of 41 congeners) was 7.1 ng/g lipid, ranging from 0.48 to 1980 ng/g lipid. Among these PBDE congeners, the median sum of the tri- to hepta-PBDE (ΣPBDE3−7) congener concentrations was 2.9 ng/g lipid, ranging from 0.48 to 20 ng/g lipid. The most common tri- to heptabrominated congeners were BDE-47 (30% of total), BDE-99 (24%), BDE-183 (15%), BDE-153 (12%), BDE-28 (9.5%), and BDE-100 (6.2%). These levels of ΣPBDE3−7 were similar to those observed in Europe and Asia but were much lower than those observed in North America. Highly brominated BDE congeners were detected in some serum samples. In particular, BDE-209 was detected in 28 samples; the median BDE-209 concentration in these samples was 42 ng/g lipid, ranging from ND to 1770 ng/g lipid. The total PBDE levels in office cleaners were significantly higher than in university students and policemen. In addition, we also measured several other BFRs. Hexabromobenzene (HBB) was identified in 26 samples with a median concentration of 0.27 ng/g lipid, ranging from 0.11 to 1.50 ng/g lipid. Pentabromoethylbenzene (PBEB), hexabromocyclododecane (HBCD), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and decabromodiphenylethane (DBDPE) were not detected in any of these samples.

•The major impurity in the three PFOS products in China was PFOA (>10%).•The predominant impurity in the five commercial PFOA products was PFOS.•The percentage of n-PFOS in PFOS products in China was similar to 3M ECF PFOS.•ECF is still being used to produce PFOA in China.Perfluoroalkyl acids (PFAAs) have been widely used in consumer and industrial products for decades and are widely detected in the environment and humans all over the world. The information on the isomeric profiles of commercial products is important to identify the manufacturing origins of PFAAs in the environment. For the first time, the PFAA compositions and isomeric profiles of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were reported in three PFOS and five PFOA commercial products manufactured in China. The purity of the three PFOS products was 76.7–80.6%. The major impurity in the PFOS products is PFOA, which contributes more than 10%. Other impurities include perfluorohexanesulfonate (PFHxS), perfluorohexanoate (PFHxA) and perfluoroheptanoate acids (PFHpA). The percentage of linear PFOS (n-PFOS) in the three products was 66.2–71.9%, similar to that in the product manufactured by 3M (70.3%). The purity of the five PFOA products was relatively high (94.0–95.8%), and the major impurity was PFOS (2.06–3.09%). The percentage of n-PFOA in the five PFOA products was 76.4–77.9%, which was similar to that in the 3M PFOA (78%). Although it is widely accepted that telomerization is currently the predominant manufacturing method for PFOA, yielding an isomerically pure and linear product, the results in the present study suggest that electrochemical fluorination is still used by some manufacturers in China.Download full-size image

•The mean proportion of n-PFOS in maternal serum was 66.7%.•The proportion of n-PFOA was much higher than in 3M ECF standard.•The proportion of n-PFOS was negatively correlated with the concentration of ∑PFOS.•The levels of most PFCAs correlated with albumin significantly.•The percentages of PFOS or PFOA isomers were related to some health parameters.Perfluoroalkyl acids (PFAAs) are a group of chemicals used for many applications and widely present in the environment and humans. In this study, serum levels of PFAAs and isomers of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were analyzed in 141 Chinese pregnant women. Among all the samples, total PFOS (∑ PFOS, mean concentration 7.32 ng/mL) was predominant, followed by ∑ PFOA (mean 4.78 ng/mL) and perfluorodecanoate (PFDA, mean 1.45 ng/mL). On average, the proportion of linear PFOS (n-PFOS) was 66.7% of ∑ PFOS, which was higher than the general population, implying that maternal women could excrete branched PFOS isomers to the fetus by transplacental transfer. Moreover, the proportion of n-PFOS decreased significantly with the increasing concentration of ∑ PFOS in the serum samples (r = − 0.342, p < 0.001). The mean proportion of n-PFOA in the serum samples was 99.0%, which was much higher than the technical ECF (electrochemical fluorination) products (ca. 70%). The small proportion of branched isomers of PFOA suggests that there is still a source of ECF PFOA in China. Significant correlations (p < 0.005) were observed between the concentrations of some PFAAs with certain medical parameters in the pregnant women. For example, the levels of most perfluorinated carboxylic acids (PFCAs) were found to correlate with albumin significantly, which might be a sign of immunotoxicity of these chemicals. The adverse effects of PFAA exposure to pregnant women may increase the health risk of the fetus. Interestingly, not only the PFAA concentrations but also the percentages of PFOS and PFOA isomers were correlated with certain medical parameters. This implies that the compositions of PFOS or PFOA should be considered in human health risk assessment in the future.Download full-size image

The sources and pathways of human exposure to perfluoroalkyl acids (PFAAs) are not well characterized, particularly in China where many perfluorinated substances are now manufactured. Here, isomer-specific PFAA analysis was used for the first time to evaluate exposure sources for Chinese people, by applying the method to 129 serum samples collected in two typical cities (Shijiazhuang and Handan) in North China. Among all samples, total perfluorooctanesulfonate (∑PFOS, mean 33.3 ng/ml) was the predominant PFAA followed by perfluorohexanesulfonate (2.95 ng/ml), total perfluorooctanoate (∑PFOA, 2.38 ng/ml), and perfluorononanoate (0.51 ng/ml). The level of ∑PFOS was higher than in people from North America in recent years. The mean concentrations of ΣPFAAs in the participants living in urban Shijiazhuang (59.0 ng/ml) and urban Handan (35.6 ng/ml) were significantly higher (p < 0.001 and p = 0.041, respectively) than those living in the rural district of Shijiazhuang (24.3 ng/ml). The young female sub-population had the lowest ΣPFAA concentrations compared with older females and all males. On average, the proportion of linear PFOS (n-PFOS) was only 48.1% of ∑PFOS, which is much lower than what was present in technical PFOS from the major historical manufacturer (ca. 70% linear), and which is also lower than data reported from any other countries. Moreover, the proportion of n-PFOS decreased significantly with increasing ∑PFOS concentration in the serum samples (r = − 0.694, p < 0.001). Taken together, the data lend weight to previous suggestions that i) high branched PFOS content in serum is a biomarker of exposure to PFOS-precursors, and ii) that people with the highest ∑PFOS concentrations are exposed disproportionately to high concentrations of PFOS-precursors. On average, linear PFOA (n-PFOA) contributed 96.1% of ∑PFOA, significantly higher than in technical PFOA (ca. 75–80% linear), but lower than in Americans, suggesting higher exposure to electrochemically fluorinated PFOA than in other countries, including the United States.Download full-size imageHighlights► The isomer profiles of PFOS and PFOA in Chinese serum samples were identified. ► Young females had the lowest level of ΣPFAAs compared to males and old females. ► Young females had the highest proportion of n-PFOS in their sera. ► The proportion of n-PFOS decreased with an increase in ∑PFOS concentration. ► Branched PFOA in serum is a strong indicator of human exposure to ECF PFOA.

•Ti in colloids of WWTP effluents and receiving streams were mainly from nano-TiO2.•Most of nano-TiO2 (74–85%) in the influent was removed by the activated sludge.•WWTP effluents and other sources, such as runoff, contribute to Ti in receiving water.•Ti was accumulated in edible fish tissue due to the long term exposure.Wastewater treatment plants (WWTPs) can be important point sources for the discharge of engineered nanomaterials to natural surface waters. In this study, we investigated the fate of nano-TiO2 in two full scale WWTPs and their receiving streams in northern China (i.e., the Binhe and Minxin rivers, which flow to the Xiaohe River). High resolution transmission electron microscopy, energy dispersion X-ray spectroscopy and X-ray photoelectron spectroscopy analyses indicated that Ti in colloids present in the WWTP effluents and receiving streams originated mainly from engineered nano-TiO2. Most of the nano-TiO2 (74–85%) in the influent sewage was removed by the activated sludge, but significant concentrations (27–43 μg/L Ti) remained associated with colloids in the effluents. Surprisingly, the total concentration of Ti in the receiving river streams was higher (52–86 μg/L), indicating the importance of other sources such as urban runoff. These relatively high Ti concentrations are unlikely to originate from natural sources since they are significantly higher than those in the nearby Yuqiao Reservoir (< 5 μg/L), representing regional background levels. Consistently, Ti levels in fish collected from the Xiaohe River (including muscle and other tissues) were significantly higher than those of fish from the reservoir. Overall, TiO2 releases through WWTP effluents and other sources (including runoff) are contributing to the relatively high observed concentrations of suspended Ti in the Xiaohe River, which results in accumulation in edible fish tissue.

•The isomer profiles of PFOS and PFOA in Chinese young couples were measured.•Young females had significantly lower level of PFSAs than young males.•Menstruation could be an effective pathway to eliminate PFSAs for young females.•Young females had higher proportion of n-PFOS than young males.•Most branched PFOS isomers were enriched in humans compared to commercial products.A total of 100 serum samples from 50 new couples (none of the females in this study has ever been pregnant) in Tianjin, North China, were analyzed for eleven perfluoroalkyl acids (PFAAs) with isomer-specific method. Among all samples, total perfluorooctanesulfonate (∑ PFOS, mean 11.3 ng/mL) was predominant followed by total perfluorooctanoate (∑ PFOA, 2.95 ng/mL), perfluorodecanoate (PFDA, 1.17 ng/mL), perfluorononanoate (PFNA, 0.93 ng/mL) and perfluorohexanesulfonate (PFHxS, 0.67 ng/mL). The mean concentrations of ∑ PFOS and PFHxS in males (14.2 and 0.89 ng/mL) were significantly higher (p = 0.001) than in females (8.36 and 0.45 ng/mL). No statistical difference between genders was observed for the other PFAAs. This suggests that menstruation is one important elimination pathway for ∑ PFOS and PFHxS in females. Linear PFOA was the dominant isomer with mean proportion of 99.7%, suggesting that telomeric PFOA (and its precursors), which contains almost pure linear isomer, might be the dominant exposure source of PFOA in Tianjin. On average, the proportion of linear PFOS (n-PFOS) was 59.2% of ∑ PFOS, which was lower than that in technical PFOS products (ca. 70% linear). Except perfluoroisopropyl PFOS, all the other monomethyl branched PFOS isomers were enriched in human serum compared to the commercial products, suggesting the monomethyl branched PFOS precursors were preferentially biotransformed in humans.Download full-size image

•The bioaccumulation factors (BAFs) of bisphenol analogues in biota from Taihu Lake were investigated.•Positive relationship between log BAFs and log Kow values observed for bisphenol analogues•The measured log BAFs of bisphenol analogues were in line with the values calculated by EPI Suite model.•Biomagnification of BPAF, BPC and BPZ were observed in food web of Taihu Lake.Due to regulations on bisphenol A (BPA) in many countries, a variety of bisphenol analogues are being widely manufactured and applied. However, there is a big knowledge gap on bioaccumulation and biomagnification of these emerging bisphenols in aquatic organisms. The bioaccumulation and magnification of nine bisphenol analogues in aquatic organisms at different trophic levels collected from Taihu Lake, China, were evaluated. The total concentrations of the nine bisphenols in the lake waters were in the range of 49.7–3480 ng/L (mean, 389 ng/L). BPA, bisphenol AF (BPAF) and bisphenol S (BPS) were the most predominant analogues in the water. The mean natural logarithm bioaccumulation factor (log BAFs) of BPAF, bisphenol C (BPC), bisphenol Z (BPZ) and bisphenol E (BPE) were greater than BPA, and there was a significantly positive correlation between log BAFs of the biphenols and their octanol-water partition coefficients (log Kow). The trophic magnification factors of BPAF, BPC and BPZ were 2.52, 2.69 and 1.71, respectively, suggesting that they had the potential to biomagnify in the food web. The results of this study call for further investigations on risk assessment of these emerging pollutants in the environment.Download high-res image (251KB)Download full-size image