Health & Environmental Research Online (HERO)


PFHxS (355-46-4)


254 References Were Found:

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

An investigation of the effects of geometry design on refrigerant flow mal-distribution in parallel flow condenser using a hybrid method of finite element approach and CFD simulation

Authors: Shojaeefard, MH; Nourbakhsh, SD; Zare, J (2017) HERO ID: 3859952

[Less] Flow mal-distribution in tubes is an important problem in parallel flow heat exchangers (PFHXs) which . . . [More] Flow mal-distribution in tubes is an important problem in parallel flow heat exchangers (PFHXs) which should be considered in heat exchanger modeling. In the present study, a hybrid method is developed for flow distribution forecasting based on simultaneous use of computational fluid dynamics (CFD) simulation for 3D analysis of flow in PFHX headers and finite element model for solving flow within tubes. The developed method forecasts are verified against the experimental data of a parallel flow condenser (PFC) performance. The method is then utilized to investigate the effects of tube protrusion depth, inlet tube location, inlet tube diameter and combination of tube protrusion depth and inlet tube location on refrigerant flow mal-distribution. The data indicate flow mal-distribution increment (increase of standard deviation (STD) from 0.51% to 1.77%) by increasing the tube protrusion depth from 1/4 to 3/4 of header diameter which results in about 14% increment in pressure drop and 3.9% decrement in capacity. Also, reduction of flow mal-distribution in cases of increasing the inlet tube diameter and locating the header inlet on the top of the header, a small distance away from the first tube is observed. The presented model and results can be used to accurately design PFCs. (C) 2016 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Developing a hybrid procedure of one dimensional finite element method and CFD simulation for modeling refrigerant flow mal-distribution in parallel flow condenser

Authors: Shojaeefard, MH; Zare, J; Nourbakhsh, SD (2017) HERO ID: 3859953

[Less] Mal-distribution of refrigerant flow in flat tubes is an important problem in parallel flow heat exchangers . . . [More] Mal-distribution of refrigerant flow in flat tubes is an important problem in parallel flow heat exchangers (PFHXs) which should be considered in heat exchanger modeling. In the present study, a hybrid method is developed for flow distribution forecasting based on simultaneous use of computational fluid dynamics (CFD) simulation for 3D analysis of flow in PFHX headers and one dimensional finite element model for solving flow within flat tubes. The experimental data of a parallel flow condenser (PFC) performance is collected to verify the developed method. The average absolute deviations of 2.8%, 4.1% and 3% from experimental data for pressure drop, capacity and outlet temperature respectively, indicate the model validity. Slight increase of mass flow rate with moving toward the bottom tubes of the inlet header shows insignificant effect of gravity when vapor-phase flow is present. Also, comparing the pressure drop data of the developed method with those of uniform distribution model demonstrates reduction of average absolute deviation from 28.7% to 2.8%. The proposed model has the advantage of predicting PFC overall performance and can be used to accurately design and optimize headers and multiport flat tubes. (C) 2016 Elsevier Ltd and IIR. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

A Robust Method for Routine Analysis of Perfluorooctane Sulfonate (PFOS) and Perfluorohexane Sulfonate (PFHxS) in Various Edible Crop Matrices

Authors: Xiang, Lei; Sun, TFei; Chen, Lei; Xiao, Tao; Cai, QY; Li, Hui; He, DeC; Wong, MH; Li, YanWen; Mo, CeHui (2017) HERO ID: 3859955

[Less] A reliable, sensitive, and efficient method was developed for routine analysis of perfluorooctane sulfonate . . . [More] A reliable, sensitive, and efficient method was developed for routine analysis of perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) in various edible crop matrices including cereal (grain), root vegetable (carrot), leafy vegetable (lettuce), and melon vegetable (pumpkin). The target analytes were extracted by ion-pair approach followed by solid-phase extraction clean-up and HPLC-MS/MS. The type of extraction solvent, clean-up cartridge, and the usage of Supelclean graphitized carbon were evaluated to reach an optimized pretreatment procedure. The matrix-matched standard calibrations relative to the isotope-labeled internal standard were used in the developed method to obtain more reliable quantitative results. The average recoveries at four spiked levels (0.5, 10, 25, 50 ng/g) in the diverse matrices ranged from 70.9 to 114.6% with relative standard deviations (RSD) lower than 11.5%. The matrix-dependent method detection limits using the common equipment (HPLC-MS/MS) were between 0.020 and 0.140 ng/g (dw), equivalent to the 3-130 pg/g (fw), corresponding to the sensitivity of superior equipment (e.g., UPLC-MS/MS and HPLC-QTOF-HRMS). Furthermore, the developed method was conferred with the practicality through determination of the analytes in actual crops sampled from several farms in China's Pearl River Delta.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Spatial distribution and source tracing of per- and polyfluoroalkyl substances (PFASs) in surface water in Northern Europe

Authors: Nguyen, MA; Wiberg, K; Ribeli, E; Josefsson, S; Futter, M; Gustavsson, J; Ahrens, L (2017) Environmental Pollution 220:1438-1446. HERO ID: 3605095

[Less] The impact of point and diffuse sources for 26 per- and polyfluoroalkyl substances (PFASs) in northern . . . [More] The impact of point and diffuse sources for 26 per- and polyfluoroalkyl substances (PFASs) in northern Europe were investigated by studying Swedish rivers (n = 40) and recipient seawater (Baltic Sea and Kattegat; n = 18). Different composition profiles were observed in the rivers, with ten rivers having a remarkably high fraction of perfluoroalkane sulfonic acids (PFSAs; 65% of the ƩPFASs) as compared to other rivers (19%) suggesting major impact of one or several source types dominated by PFSAs. Population density and low latitude (south) were strongly correlated to the widely used perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) as well as to perfluorohexanesulfonic acid (PFHxS). Significant relationships between several PFCAs and PFSAs (i.e. perfluorobutanoic acid (PFBA), perfluoroheptanoic acid (PFHpA), PFOA, perfluorobutanesulfonic acid (PFBS), and PFHxS) and dissolved organic carbon (DOC) were detected (p < 0.05), indicating chemical binding and co-transport with DOC in fresh water and seawater. Partial least squares regression analysis showed that perfluoroalkyl carboxylic acids (PFCAs) were related to latitude according to their perfluorocarbon chain length (C3, C7, C8, C9, C10 and C11), with longer chains associated with higher latitudes. This suggests the presence of mechanisms promoting higher prevalence of longer chained PFCAs in the north, e.g. precursor degradation, and/or aerosol associated stabilization of PFCAs and their precursors.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Estimating human exposure to perfluoroalkyl acids via solid food and drinks: Implementation and comparison of different dietary assessment methods

Authors: Papadopoulou, E; Poothong, S; Koekkoek, J; Lucattini, L; Padilla-Sánchez, JA; Haugen, M; Herzke, D; Valdersnes, S; Maage, A; Cousins, IT; Leonards, PEG; Småstuen Haug, L (2017) Environmental Research 158:269-276. HERO ID: 3859798

[Less] BACKGROUND: Diet is a major source of human exposure to hazardous environmental chemicals, . . . [More] BACKGROUND: Diet is a major source of human exposure to hazardous environmental chemicals, including many perfluoroalkyl acids (PFAAs). Several assessment methods of dietary exposure to PFAAs have been used previously, but there is a lack of comparisons between methods.

AIM: To assess human exposure to PFAAs through diet by different methods and compare the results.

METHODS: We studied the dietary exposure to PFAAs in 61 Norwegian adults (74% women, average age: 42 years) using three methods: i) by measuring daily PFAA intakes through a 1-day duplicate diet study (separately in solid and liquid foods), ii) by estimating intake after combining food contamination with food consumption data, as assessed by 2-day weighted food diaries and iii) by a Food Frequency Questionnaire (FFQ). We used existing food contamination data mainly from samples purchased in Norway and if not available, data from food purchased in other European countries were used. Duplicate diet samples (n=122) were analysed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to quantify 15 PFAAs (11 perfluoroalkyl carboxylates and 4 perfluoroalkyl sulfonates). Differences and correlations between measured and estimated intakes were assessed.

RESULTS: The most abundant PFAAs in the duplicate diet samples were PFOA, PFOS and PFHxS and the median total intakes were 5.6ng/day, 11ng/day and 0.78ng/day, respectively. PFOS and PFOA concentrations were higher in solid than liquid samples. PFOS was the main contributor to the contamination in the solid samples (median concentration 14pg/g food), while it was PFOA in the liquid samples (median concentrations: 0.72pg/g food). High intakes of fats, oils, and eggs were statistically significantly related to high intakes of PFOS and PFOA from solid foods. High intake of milk and consumption of alcoholic beverages, as well as food in paper container were related to high PFOA intakes from liquid foods. PFOA intakes derived from food diary and FFQ were significantly higher than those derived from duplicate diet, but intakes of PFOS derived from food diary and FFQ were significantly lower than those derived from duplicate diet. We found a positive and statistically significant correlation between the PFOS intakes derived from duplicate diet with those using the food diary (rho=0.26, p-value=0.041), but not with the FFQ. Additionally, PFOA intakes derived by duplicate diet were significantly correlated with estimated intakes from liquid food derived from the food diary (rho=0.34, p=0.008) and estimated intakes from the FFQ (rho=0.25, p-value=0.055).

CONCLUSIONS: We provide evidence that a food diary or a FFQ-based method can provide comparable intake estimates to PFOS and PFOA intakes derived from a duplicate diet study. These less burdensome methods are valuable and reliable tools to assess dietary exposure to PFASs in human studies.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Diet and metabolic state are the main factors determining concentrations of perfluoroalkyl substances in female polar bears from Svalbard

Authors: Tartu, S; Bourgeon, S; Aars, J; Andersen, M; Lone, K; Jenssen, BM; Polder, A; Thiemann, GW; Torget, V; Welker, JM; Routti, H (2017) Environmental Pollution 229:146-158. HERO ID: 3859801

[Less] Perfluoroalkyl substances (PFASs) have been detected in organisms worldwide, including Polar Regions. . . . [More] Perfluoroalkyl substances (PFASs) have been detected in organisms worldwide, including Polar Regions. The polar bear (Ursus maritimus), the top predator of Arctic marine ecosystems, accumulates high concentrations of PFASs, which may be harmful to their health. The aim of this study was to investigate which factors (habitat quality, season, year, diet, metabolic state [i.e. feeding/fasting], breeding status and age) predict PFAS concentrations in female polar bears captured on Svalbard (Norway). We analysed two perfluoroalkyl sulfonates (PFSAs: PFHxS and PFOS) and C8-C13 perfluoroalkyl carboxylates (PFCAs) in 112 plasma samples obtained in April and September 2012-2013. Nitrogen and carbon stable isotope ratios (δ(15)N, δ(13)C) in red blood cells and plasma, and fatty acid profiles in adipose tissue were used as proxies for diet. We determined habitat quality based on movement patterns, capture position and resource selection functions, which are models that predict the probability of use of a resource unit. Plasma urea to creatinine ratios were used as proxies for metabolic state (i.e. feeding or fasting state). Results were obtained from a conditional model averaging of 42 general linear mixed models. Diet was the most important predictor of PFAS concentrations. PFAS concentrations were positively related to trophic level and marine diet input. High PFAS concentrations in females feeding on the eastern part of Svalbard, where the habitat quality was higher than on the western coast, were likely related to diet and possibly to abiotic factors. Concentrations of PFSAs and C8-C10 PFCAs were higher in fasting than in feeding polar bears and PFOS was higher in females with cubs of the year than in solitary females. Our findings suggest that female polar bears that are exposed to the highest levels of PFAS are those 1) feeding on high trophic level sea ice-associated prey, 2) fasting and 3) with small cubs.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Occurrence and incidence of 18 per- and polyfluoroalkyl compounds in edible oils commonly consumed in Guiyang, China

Authors: Yang, H; Li, G; Rao, Z; Guo, F; Li, Z; Xie, F; Tan, H (2017) Food Additives & Contaminants: Part A: Chemistry, Analysis, Control, Exposure & Risk Assessment 34:1573–1583. HERO ID: 3859802

[Less] A systematic examination was conducted for the first time of a wide carbon-chain range of per- and polyfluoroalkyl . . . [More] A systematic examination was conducted for the first time of a wide carbon-chain range of per- and polyfluoroalkyl compounds (PFASs) in 83 samples of edible vegetable and animal oils from Guiyang, China. The occurrence and levels of 18 PFASs in seven types of edible oil were analysed. Analytes were determined based on a simplified, sensitive and reliable solvent extraction and liquid chromatography-tandem mass spectrometry method. Ten target PFASs were found and the most frequently detected compounds with maximum concentration were PFOS (88%, 1.93 ng g(-1)), PFNA (55.4%; 6.76 ng g(-1)), PFHxS (39.8%; 0.36 ng g(-1)), and PFOA (16.9%; 0.15 ng g(-1)), respectively. The total PFASs concentrations ranged from 0.02 to 6.76 ng g(-1), with a mean of 0.94 ng g(-1). Significant differences of occurrence between vegetable oils and animal oils were demonstrated based on comparative analysis of the existing data. The investigation results showed that the effect of production reductions of PFOS and PFOA by regulatory was also reflected in edible oils. The dietary intakes of PFOS and PFOA for adults were estimated, which were lower than the available tolerable daily intake (TDI). Because of the global lack of food regulatory thresholds for most per- or polyfluoroalkyl compounds, it was difficult to draw any conclusion at this stage as to how human health is affected through exposure to these compounds. The baseline information of this study will assist in guiding the direction for future investigations and monitoring studies on occurrence, fate and human health-effect research of PFASs.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Vertical distribution of microbial communities in soils contaminated by chromium and perfluoroalkyl substances

Authors: Li, B; Bao, Y; Xu, Y; Xie, S; Huang, J (2017) Science of the Total Environment 599-600:156-164. HERO ID: 3859804

[Less] Both Bacteria and Archaea are important players in soil biogeochemical cycles. Both chromium (Cr) and . . . [More] Both Bacteria and Archaea are important players in soil biogeochemical cycles. Both chromium (Cr) and perfluoroalkyl substances (PFASs) are widely present in soil environment. However, the depth-related distribution of microbial community in soils contaminated by Cr or/and PFASs remains unknown. Hence, the present study applied quantitative PCR assay and Illumina MiSeq sequencing to investigate the vertical variations of archaeal and bacterial communities in soils (0.5-12.5m depth) contaminated by chrome plating waste and the potential effects of Cr and PFASs. Both bacterial and archaeal communities displayed the remarkable depth-related changes of abundance (2.16×10(7)-5.05×10(9) and 4.95×10(5)-2.56×10(8) 16S rRNA gene copies per gram dry soil respectively for Bacteria and Archaea), diversity (bacterial and archaeal Shannon diversity indices of 5.06-6.34 and 2.91-4.61, respectively) and structure. However, at each soil depth, bacterial community had higher abundance, richness and diversity than archaeal community. Soil bacterial communities were mainly composed of Proteobacteria, Chloroflexi, Actinobacteria and Firmicutes, and archaeal communities were dominated by Thaumarchaeota and unclassified Archaea. Moreover, microbial abundance and richness increased with increasing perfluorohexane sulfonate (PFHxS) content. Microbial abundance was correlated to total Cr, and archaeal richness was correlated to total Cr and Cr(IV). In addition, total Cr might be a key determinant of soil microbial community structure.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Fate and redistribution of perfluoroalkyl acids through AFFF-impacted groundwater

Authors: Bräunig, J; Baduel, C; Heffernan, A; Rotander, A; Donaldson, E; Mueller, JF (2017) Science of the Total Environment 596-597:360-368. HERO ID: 3859805

[Less] Leaching of perfluoroalkyl acids (PFAAs) from a local point source, a fire-fighting training area, has . . . [More] Leaching of perfluoroalkyl acids (PFAAs) from a local point source, a fire-fighting training area, has led to extensive contamination of a groundwater aquifer which has spread underneath part of a nearby town, Oakey, situated in the State of Queensland, Australia. Groundwater is extracted by residents from privately owned wells for daily activities such as watering livestock and garden beds. The concentration of 10 PFAAs in environmental and biological samples (water, soil, grass, chicken egg yolk, serum of horses, cattle and sheep), as well as human serum was investigated to determine the extent of contamination in the town and discuss fate and redistribution of PFAAs. Perfluorooctane sulfonate (PFOS) was the dominant PFAA in all matrices investigated, followed by perfluorohexane sulfonate (PFHxS). PFOS concentrations measured in water ranged between <0.17-14μg/L, concentrations of PFHxS measured between <0.07-6μg/L. PFAAs were detected in backyards (soil, grass), livestock and chicken egg yolk. Significant differences (p<0.01) in PFOS and PFHxS concentrations in two groups of cattle were found, one held within the contamination plume, the other in the vicinity but outside of the contamination plume. In human serum PFOS concentrations ranged from 38 to 381μg/L, while PFHxS ranged from 39 to 214μg/L. Highest PFOS concentrations measured in human serum were >30-fold higher compared to the general Australian population. Through use of contaminated groundwater secondary sources of PFAA contamination are created on private property, leading to further redistribution of contamination and creation of additional human exposure pathways.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Perfluoroalkyl substances with isomer analysis in umbilical cord serum in China

Authors: Zhang, YZ; Zeng, XW; Qian, ZM; Vaughn, MG; Geiger, SD; Hu, LW; Lu, L; Fu, C; Dong, GH (2017) Environmental Science and Pollution Research 24:13626-13637. HERO ID: 3859809

[Less] Perfluoroalkyl substances (PFASs) are a class of widely used chemicals that have been detected in the . . . [More] Perfluoroalkyl substances (PFASs) are a class of widely used chemicals that have been detected in the environment and general population. However, the isomer patterns in human are poorly characterized. Previous studies observed the isomer-specific maternal-fetal transfer of PFASs in human. In our current study, we first examined the profile of PFASs and isomers, including 17 linear PFASs and 10 branched PFOS/PFOA isomers by using isotopic internal standards in umbilical cord serum samples from Guangzhou, China. We collected a total of 321 of cord blood serum samples from July to October in 2013, and analyzed the PFASs concentration with isomer-specific PFASs analysis method. The results showed that 9 out of 17 PFASs (linear PFASs) were detected (>50% detection rate). Perfluorohexane sulfonate (PFHxS, median 3.87 ng/mL) was the predominant, followed by total PFOS (median 2.99 ng/mL) and total PFOA (median 1.23 ng/mL) in cord serum. In addition, 1m-, iso-, ∑3+4+5m-PFOS and iso-PFOA were the branched PFASs detected in the current study. The proportion of linear PFOS (n-PFOS) was 75.16% of ∑PFOS which was similar to the proportion of electrochemical fluorination that produces ca. 70% linear PFOS and 30% branched. On the contrary, linear PFOA (n-PFOA) accounted for 98.69% ∑PFOA in cord serum samples. Our finding indicates distinct PFASs and PFOS/PFOA isomer profile in cord serum, suggesting there might be a different exposure pathway and metabolism of PFASs.