Polyfluorinated substances in abiotic standard reference materials

Development of a supramolecular solvent-based extraction method for application to quantitative analyses of a wide range of organic contaminants in indoor dust

This study investigates the efficacy of supramolecular solvent (SUPRAS) in extracting a diverse spectrum of organic contaminants from indoor dust. Initially, seven distinct SUPRAS were assessed across nine categories of contaminants to identify the most effective one. A SUPRAS comprising Milli-Q water, tetrahydrofuran, and hexanol in a 70:20:10 ratio, respectively, demonstrated the best extraction performance and was employed for testing a wider array of organic contaminants. Furthermore, we applied the selected SUPRAS for the extraction of organic compounds from the NIST Standard Reference Material (SRM) 2585. In parallel, we performed the extraction of NIST SRM 2585 with conventional extraction methods using hexane:acetone (1:1) for non-polar contaminants and methanol (100%) extraction for polar contaminants. Analysis from two independent laboratories (in Norway and the Czech Republic) demonstrated the viability of SUPRAS for the simultaneous extraction of twelve groups of organic contaminants with a broad range of physico-chemical properties including plastic additives, pesticides, and combustion by-products. However, caution is advised when employing SUPRAS for highly polar contaminants like current-use pesticides or volatile substances like naphthalene.

Characterization of organophosphate esters (OPEs) and polyfluoralkyl substances (PFASs) in settled dust in specific workplaces

An analytical method for detecting flame retardants was slightly modified and optimized for the simultaneous determination of 11 organophosphate esters (OPEs) and 26 polyfluoralkyl substances (PFASs) contained in dust. All the analytes were determined in HPLC/MS-MS, and OPEs were also analyzed in GC/MS, and the results were compared. The study was conducted through the investigation of the Standard Reference Material SRM 2585 of the National Institute of Standard and Technology (NIST). The results were compared with the available reference mass fraction reported in the NIST certificate. The mass fraction obtained for the other OPEs and PFASs was compared to available data in the literature. After verifying the reliability of the results, the method was applied to environmental samples of settled dust, collected in four workplaces, where OPE and PFAS content is expected to be higher than in house dust: a mechanical workshop, an electronic repair center, a disassembly site, and a shredding site of two electronic waste recycling plants. By analyzing both PFASs and OPEs in the same samples, the present work demonstrated that the selected working places were more polluted in OPEs than houses; on the contrary, PFAS content in house dust proved to be more than ten times higher than that in workplaces. Additional research is necessary to confirm these data. Nevertheless, because this preliminary study showed not negligible concentrations of OPEs in some workplaces and of PFASs in houses, their monitoring should be extended to other domestic and selected working sites.

Screening and Demulsification Mechanism of Fluorinated Demulsifier Based on Molecular Dynamics Simulation

In order to solve the problem of demulsification difficulties in Liaohe Oilfield, 24 kinds of demulsifiers were screened by using the interface generation energy (IFE) module in the molecular dynamics simulation software Materials Studio to determine the ability of demulsifier molecules to reduce the total energy of the oil–water interface after entering the oil–water interface. Neural network analysis (NNA) and genetic function approximation (GFA) were used as technical means to predict the demulsification effect of the Liaohe crude oil demulsifier. The simulation results show that the SDJ9927 demulsifier with ethylene oxide (EO) and propylene oxide (PO) values of 21 (EO) and 44 (PO) reduced the total energy and interfacial tension of the oil–water interface to the greatest extent, and the interfacial formation energy reached −640.48 Kcal/mol. NNA predicted that the water removal amount of the SDJ9927 demulsifier was 7.21 mL, with an overall error of less than 1.83. GFA predicted that the water removal amount of the SDJ9927 demulsifier was 7.41mL, with an overall error of less than 0.9. The predicted results are consistent with the experimental screening results. SDJ9927 had the highest water removal rate and the best demulsification effect. NNA and GFA had high correlation coefficients, and their R²s were 0.802 and 0.861, respectively. The higher R² was, the more accurate the prediction accuracy was. Finally, the demulsification mechanism of the interfacial film breaking due to the collision of fluorinated polyether demulsifiers was studied. It was found that the carbon–fluorine chain had high surface activity and high stability, which could protect the carbon–carbon bond in the demulsifier molecules to ensure that there was no re-emulsion due to the stirring external force.

Synthesis and Study of a New Type of Fluorinated Polyether Demulsifier for Heavy Oil Emulsion Demulsification

To solve the problem of heavy oil demulsification difficulties in Liaohe Oilfield, phenolamine resin initiator was synthesized from p-trifluoromethyl phenol, and then FB series fluorinated polyether demulsifiers were synthesized by block polymerization using ethylene oxide (EO) and propylene oxide (PO) as raw materials. The demulsifiers were characterized by infrared spectroscopy, cloud point, hydrophilic-lipophilic balance (HLB) value, and surface tension. The demulsifying and dehydrating properties were tested by demulsifying and dehydrating experiments, the demulsification mechanism was analyzed by the microscopic demulsification process test, and the influence of demulsifier addition and demulsifying temperature on demulsifying performance was also studied. The results showed that under the condition of the optimum demulsification temperature of 60 °C and the optimum demulsifier dosage of 100 mg/L, the water removal (%) of fluorinated polyether demulsifier of FB 4 was the highest, and the overall water removal (%) of 50 mL crude oil emulsion in Liaohe Oilfield reached 90.33% within 2 h, which was better than the current demulsifier used in Liaohe crude oil.

Per- and polyfluoroalkyl substances (PFAS) in sediments collected from the Pensacola Bay System watershed

Sediment samples from 25 locations in the Pensacola Bay System (PBS) watershed were analyzed for the presence of 51 per- and polyfluoroalkyl substances (PFAS) using ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and selected reaction monitoring. Results revealed quantifiable concentrations of PFAS in all sampling locations. More specifically, perfluorobutanoic acid (PFBA) was present in every sediment sample with a minimum and maximum concentration of 0.04 to 0.48 ng g-1 dry weight, respectively, across the 25 sites with an average of 0.1 ± 0.09 ng g-1. While PFOS, with an average of 0.11 ± 0.14 ng g-1 (range: Collapse

Key Words

• Pensacola Bay System
• Per-and polyfluoroalkyl substances (PFAS)
• Sediment
• Storm events
• UHPLC-MS/MS

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MESH Headings Collapse

Grants

• EPA999999 Intramural EPA

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Affiliation(s)

Atiye Ahmadireskety Chemistry Department, University of Florida, Gainesville, Florida, USA
Bianca F. Da Silva College of Veterinary Medicine, Department of Physiological Sciences, University of Florida, Gainesville, Florida, USA
Jill A. Awkerman Gulf Ecosystem Measurement & Modeling Division, US Environmental Protection Agency, Gulf Breeze, Florida, USA
Joe Aufmuth George A. Smathers Libraries, University of Florida, Gainesville, Florida, USA
Richard A. Yost Chemistry Department, University of Florida, Gainesville, Florida, USA
John A. Bowden Chemistry Department, University of Florida, Gainesville, Florida, USA College of Veterinary Medicine, Department of Physiological Sciences, University of Florida, Gainesville, Florida, USA

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Per- and polyfluoroalkyl substances (PFASs) in Swedish household dust and exposure of pet cats

Per- and polyfluoroalkyl substances (PFASs) are used in a wide range of products and have been found ubiquitously in our indoor environment, and there is evidence that exposure to PFAS can lead to adverse endocrine effects, such as thyroid hormone disruption. Pet cats have a high dust intake due to their grooming behavior and have been shown to be a suitable sentinel species for assessment of toddler's exposure. Here we used paired household dust (n=46) and cat serum (n=27) samples to establish whether dust is a relevant exposure pathway to PFASs. An analytical method for PFAS analysis was optimized using a low volume of cat serum samples, combining solid-phase extraction and online sample cleanup. Dust was extracted with methanol by sonication and cleaned up by addition of active carbon. In total, 27 PFASs were analyzed by liquid chromatography/mass spectrometry analysis. The correlation between PFAS levels in dust and serum, serum lipids and thyroid hormone levels, and PFAS levels in dust between different rooms were statistically evaluated. PFOS and PFDA could be quantified in all cat serum samples (median 2300 pg/mL and 430 pg/mL, respectively), followed by PFOA (median 1100 pg/mL), quantified in 96% of the samples. The levels of 6:2 and 8:2 diPAPs were determined in 65% and 92% of the serum samples, respectively, and were an order of magnitude lower (1.4-160 pg/mL). Household dust on the other hand was dominated by 6:2 and 8:2 diPAPs, with a median of 65 ng/g dust and 49 ng/g dust, respectively. PFOS (median 13 ng/g dust) and PFOA (median 9 ng/g dust) were quantified in 93% of the dust samples. Only eight PFASs were detected (>LOD) in at least 50% of the samples of both matrices and could be paired. Significant correlations between cat serum and dust were found for PFOA (rS=0.32, p<0.049) and PFUnDA (rS=0.55, p<0.001). Significant positive correlations were found between serum total thyroxine (rS=0.11, p<0.05) and PFNA and between serum cholesterol and PFHpA (rS=0.46, p<0.01), PFUnDA (rS=0.40, p<0.05), PFDoDA (rS=0.44, p<0.01), and sum PFAS (rS=0.48, p<0.01). In conclusion, this study confirmed that dust is a relevant exposure pathway for the ingestion of some PFASs for cats, and the serum levels of PFASs could be of relevance for the cat's health.

Evaluation of extraction workflows for quantitative analysis of per- and polyfluoroalkyl substances: A case study using soil adjacent to a landfill

Specific aspects of previously reported extraction workflows, for measurement of per- and polyfluoroalkyl substances (PFAS) in solid matrices, have not been adequately interrogated. The objective of this study was to explore the importance of each workflow step in providing the most appropriate extraction for a comprehensive set of PFAS (51 different species) in soil. We compared different procedures, including two pre-extraction set ups (overnight handling of samples prior to extraction), two extraction solvents (methanol (MeOH), and acetonitrile (ACN)), two extraction solvent volumes (10 mL and 8.5 mL), and two post-extraction cleanup strategies (ENVI-Carb and ion-pair). Of the 51 species targeted, 21 were at quantifiable levels in soil samples collected adjacent to a landfill, of which 13 PFAS were consistently detected among the different extraction workflows. Overall, results showed no significant difference in PFAS concentration between different extraction solvents and cleanup strategies. Perfluoropentanoic acid, perfluorohexanoic acid, and perfluorooctanoic acid had the highest concentrations in all extraction workflows, accounting for nearly 13%, 38%, and 17% of the total monitored PFAS (ΣPFAS), respectively. While final concentration values were similar across methods, recovery and accuracy studies showed that MeOH had the best recovery, with 88% of the isotopically labeled PFAS standards showing extraction recovery within the acceptable range of 80% to 120% (compared to 14% of isotopically labeled PFAS standards in workflows using ACN). Upon examination of additional cleanup steps, 67% of monitored PFAS (out of 51 total PFAS monitored), on average, exhibited higher accuracy (relative error ≤20%) using ENVI-Carb clean up (in comparison with 51% in workflows using ion pair clean up). Results also demonstrated that larger volumes of MeOH (and subsequent re-extractions) did not yield a better recovery, enabling a reduction in overall analysis time and cost in comparison to many published methods.

Per- and Polyfluoroalkyl Substances in Dust Collected from Residential Homes and Fire Stations in North America

Over the past few years, human exposure to per- and polyfluoroalkyl substances (PFAS) has garnered increased attention. Research has focused on PFAS exposure via drinking water and diet, and fewer studies have focused on exposure in the indoor environment. To support more research on the latter exposure pathway, we conducted a study to evaluate PFAS in indoor dust. Dust samples from 184 homes in North Carolina and 49 fire stations across the United States and Canada were collected and analyzed for a suite of PFAS using liquid and gas chromatography-mass spectrometry. Fluorotelomer alcohols (FTOHs) and di-polyfluoroalkyl phosphoric acid esters (diPAPs) were the most prevalent PFAS in both fire station and house dust samples, with medians of approximately 100 ng/g dust or greater. Notably, perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate, perfluorononanoic acid, and 6:2 diPAP were significantly higher in dust from fire stations than from homes, and 8:2 FTOH was significantly higher in homes than in fire stations. Additionally, when comparing our results to earlier published values, we see that perfluoroalkyl acid levels in residential dust appear to decrease over time, particularly for PFOA and PFOS. These results highlight a need to better understand what factors contribute to PFAS levels in dust and to understand how much dust contributes to overall human PFAS exposure.

Characterizing and Comparing Per- and Polyfluoroalkyl Substances in Commercially Available Biosolid and Organic Non-Biosolid-Based Products

There is increasing concern over the presence of per- and polyfluoroalkyl substances (PFAS) in biosolids, while sales in commercially available biosolid-based products used as soil amendments are also increasing. Here, the occurrence of 17 perfluoroalkyl acids (PFAAs) present in 13 commercially available biosolid-based products, six organic composts (manure, mushroom, peat, and untreated wood), and one food and yard waste compost were studied. The PFAA concentration ranges observed are as follows: biosolid-based products (9.0-199 μg/kg) > food and yard waste (18.5 μg/kg) > other organic products (0.1-1.1 μg/kg). Analysis of 2014, 2016, and 2018 bags produced from one product line showed a temporal decrease in the total PFAAs (181, 101, and 74 μg/kg, respectively). The total oxidizable precursor (TOP) assay revealed the presence of PFAA precursors in the biosolid-based products at much higher levels, when the soluble carbon was removed by the ENVI-Carb clean-up prior to the TOP assay. Time-of-flight mass spectrometry confirmed the presence of three sulfonamides, two fluorotelomer sulfonates, and several polyfluoroalkyl phosphate diesters. Pore-water concentrations of water-saturated products were primarily of short-chain PFAAs and increased with increasing PFAA concentrations in the products. A strong positive log-linear correlation between organic carbon (OC)-normalized PFAA partition coefficients and the number of CF_n units indicates that OC is a good predictor of PFAA release concentrations.

Per- and polyfluoroalkyl substances in paired dust and carpets from childcare centers

Carpets can be a significant source of per- and polyfluoroalkyl substances (PFASs) in the indoor environment and may be an especially important source of exposure for children and toddlers. Most previous studies focused on measuring indoor dust only. In this study, we measured PFAS concentrations in paired carpet and dust samples from 18 California childcare centers in 2018 to investigate carpet as a contributor to PFASs in dust. Median total PFAS concentrations (∑PFASs) in carpets and dust were 471 ng/g and 523 ng/g, respectively. 6:2 FTOH and 6:2 FTSA were the two dominant PFASs, collectively accounting for over 50% of the ∑PFASs in both media. Other frequently detected PFASs included C₄-C₁₄ perfluoroalkylcarboxylic acids, C₄-C₈ perfluoroalkylsulfonic acids, PFDS, 4:2 FTSA, 8:2 FTSA, FOSA, MeFOSE, EtFOSE, 8:2 FTOH, and 10:2 FTOH. We found strong associations between PFAS levels in carpet and dust pairs, suggesting that carpets can be a source and a sink for PFASs. The estimated total perfluoroalkyl acids (PFAA) intake via dust ingestion for children was 0.023, 0.096, and 1.9 ng/kg body weight/day in the low-, intermediate-, and high-exposure scenarios, respectively. Our data suggest that PFASs of emerging concern are playing an increasingly important role in indoor exposure to PFASs.

Perfluoroalkyl Substances in Drinking Water, Indoor Air and Dust from Ireland: Implications for Human Exposure

Perfluoroalkyl substances (PFASs) were measured in air and dust from cars, homes, offices, and school classrooms in Ireland, along with drinking water from homes and offices. Perfluorooctanoic acid (PFOA) dominated air and drinking water, while perfluorobutane sulfonate (PFBS) dominated dust. This is the first report of PFOA, perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), PFBS, and perfluorononanoic acid (PFNA) in air inside cars and school classrooms. PFOS concentrations in classroom air exceeded significantly (p ≤ 0.05) those in homes. Atmospheric concentrations of PFOA, PFNA, and methyl perfluorooctane sulfonamido ethanol (MeFOSE) (p ≤ 0.05) were significantly higher in cars containing child car seats than in cars without. PFOS, PFOA, PFBS, and PFHxS were all detected frequently in drinking water, but concentrations of PFASs were low, and although ΣPFASs were 64 ng/L in one bottled water sample, this fell below a Swedish Action Level of 90 ng ΣPFASs/L. The Irish population's exposure to PFOS and PFOA via non-dietary sources is well below estimates of dietary exposure elsewhere in Europe. Moreover, even under a high-end exposure scenario, it falls below the European Food Safety Authority's (EFSA) provisional tolerable weekly intakes for PFOS and PFOA.

Reduction of hazardous chemicals in Swedish preschool dust through article substitution actions

Consumer goods and building materials present in the preschool environment can be important sources of hazardous chemicals, such as plasticizers, bisphenols, organophosphorus and brominated flame retardants, poly- and perfluoroalkyl substances, which may pose a health risk to children. Even though exposure occurs via many different pathways, such as food intake, inhalation, dermal exposure, mouthing of toys etc., dust has been identified as a valuable indicator for indoor exposure. In the present study, we evaluate the efficiency of product substitution actions taken in 20 Swedish preschools from the Stockholm area to reduce the presence of hazardous substances in indoor environments. Dust samples were collected from elevated surfaces in rooms where children have their everyday activities, and the concentrations found were compared to the levels from a previous study conducted in 2015 at the same preschools. It was possible to lower levels of hazardous substances in dust, but their continued presence in the everyday environment of children was confirmed since bisphenol A, restricted phthalates and organophosphate esters were still detectable in all preschools. Also, an increase in the levels of some of the substitutes for the nowadays restricted substances was noted; some of the alternative plasticizers to phthalates, such as DEHA and DEHT, were found with increased concentrations. DINP was the dominant plasticizer in preschool dust with a median concentration of 389 μg/g, while its level was significantly (p = 0.012) higher at 716 μg/g in preschools with polyvinyl chloride (PVC) flooring. PBDEs were now less frequently detected in dust and their levels decreased 20% to 30%. This was one of the few times that PFAS were analyzed in preschool dust, where 6:2 diPAP was found to be most abundant with a median concentration of 1140 ng/g, followed by 6:2 PAP 151 ng/g, 8:2 diPAP 36 ng/g, N-Et-FOSAA 18 ng/g, PFOS 12 ng/g, PFOA 7.7 ng/g and PFNA 1.1 ng/g. In addition, fluorotelomer alcohols were detected in 65-90% of the samples. Children's exposure via dust ingestion was evaluated using intermediate and high daily intake rates of the targeted chemicals and established health limit values. In each case, the hazard quotients (HQs) were < 1, and the risk for children to have adverse health effects from the hazardous chemicals analyzed in this study via dust ingestion was even lower after the product substitution actions were taken in preschools.

Perfluoroalkyl acids and their precursors in floor dust of children's bedrooms - Implications for indoor exposure

We analysed floor dust samples from 65 children's bedrooms in Finland collected in 2014/2015 for 62 different per- and polyfluoroalkyl substances (PFASs) with a simple and highly efficient method. Validation results from the analysis of standard reference material (SRM) 2585 were in good agreement with literature data, while 24 PFASs were quantified for the first time. In the dust samples from children's bedrooms, five perfluoroalkyl carboxylic acids (PFCAs) and perfluorooctane sulfonic acid (PFOS) were detected in more than half of the samples with the highest median concentration of 5.26 ng/g for perfluorooctanoic acid (PFOA). However, the dust samples were dominated by polyfluoroalkyl phosphoric acid esters (PAPs) and fluorotelomer alcohols (FTOHs) (highest medians: 53.9 ng/g for 6:2 diPAP and 45.7 ng/g for 8:2 FTOH). Several significant and strong correlations (up to ρ = 0.95) were found among different PFASs in dust as well as between PFASs in dust and air samples (previously published) from the same rooms. The logarithm of dust to air concentrations (log K_dust/air) plotted against the logarithm of the octanol-air partition coefficient (log K_oa) resulted in a significant linear regression line with R² > 0.88. Higher dust levels of PFOS were detected in rooms with plastic flooring material in comparison to wood (p < 0.05). Total estimated daily intakes via dust (EDI_dust) and air (EDI_air) of perfluoroalkyl acids (PFAA), including biotransformation of precursors to PFAAs, were calculated for 10.5-year-old children. The total EDI_dust for PFOA and PFOS were estimated to be 0.007 ng/kg bw/day and 0.006 ng/kg bw/day, respectively, in an intermediate exposure scenario. The sum of the total EDIs for all PFAAs was slightly higher for dust than air (0.027 and 0.019 ng/kg bw/day). Precursor biotransformation was generally important for total PFOS intake, while for the PFCAs, FTOH biotransformation was estimated to be important for air, but not for dust exposure.

Ecological risk assessment of perfluooroctane sulfonate to aquatic fauna from a bayou adjacent to former fire training areas at a US Air Force installation

Per- and polyfluoroalkyl substances (PFASs) continue to receive significant attention, with particular concern for PFASs such as perfluorooctane sulfonate (PFOS), which was a constituent of aqueous film-forming foam used widely as a fire suppressant for aircraft since the 1970s. We were interested in the potential for risk to ecological receptors inhabiting Cooper Bayou, which is adjacent to 2 former fire-training areas at Barksdale Air Force Base (LA, USA). Previous research showed higher PFOS concentrations in surface water and biota from Cooper Bayou compared to reference sites. To estimate risk, we compared surface water concentrations from multiple sites within Cooper Bayou with several PFOS chronic toxicity benchmarks for freshwater aquatic organisms (∼0.4-5.1 μg PFOS/L) and showed probability of exceedances from 0.04 to 0.5, suggesting a potential for adverse effects in the most contaminated habitats. A tissue-residue assessment similarly showed some exceedance of benchmarks but with a lower probability (maximum = 0.17). Both fire-training areas have been inactive for more than a decade, so exposures (and, thus, risks) are expected to decline. Several uncertainties limit confidence in our risk estimates including highly dynamic surface water concentrations and limited chronic toxicity data for relevant species. Also, we have little data concerning organisms higher in the food chain which may receive higher lifetime exposures given the potential for PFOS to bioaccumulate and the longevity of many of these organisms. Overall, the present study suggests that PFOS can occur at concentrations that may cause adverse effects to ecological receptors, although additional, focused research is needed to reduce uncertainties. Environ Toxicol Chem 2018;37:2198-2209. © 2018 SETAC.

Bioaccumulation of perfluoroalkyl acids by earthworms (Eisenia fetida) exposed to contaminated soils

The presence of perfluoroalkyl acids (PFAAs) in biosolids-amended and aqueous film-forming foam (AFFF)-impacted soils results in two potential pathways for movement of these environmental contaminants into terrestrial foodwebs. Uptake of PFAAs by earthworms (Eisenia fetida) exposed to unspiked soils with varying levels of PFAAs (a control soil, an industrially impacted biosolids-amended soil, a municipal biosolids-amended soil, and two AFFF-impacted soils) was measured. Standard 28 day exposure experiments were conducted in each soil, and measurements taken at additional time points in the municipal soil were used to model the kinetics of uptake. Uptake and elimination rates and modeling suggested that steady state bioaccumulation was reached within 28 days of exposure for all PFAAs. The highest concentrations in the earthworms were for perfluorooctane sulfonate (PFOS) in the AFFF-impacted Soil A (2160 ng/g) and perfluorododecanoate (PFDoA) in the industrially impacted soil (737 ng/g). Wet-weight (ww) and organic carbon (OC)-based biota soil accumulation factors (BSAFs) for the earthworms were calculated after 28 days of exposure for all five soils. The highest BSAF in the industrially impacted soil was for PFDoA (0.42 goc/gww,worm). Bioaccumulation factors (BAFs, dry-weight-basis, dw) were also calculated at 28 days for each of the soils. With the exception of the control soil and perfluorodecanoate (PFDA) in the industrially impacted soil, all BAF values were above unity, with the highest being for perfluorohexanesulfonate (PFHxS) in the AFFF-impacted Soil A (139 gdw,soil/gdw,worm). BSAFs and BAFs increased with increasing chain length for the perfluorocarboxylates (PFCAs) and decreased with increasing chain length for the perfluoroalkyl sulfonates (PFSAs). The results indicate that PFAA bioaccumulation into earthworms depends on soil concentrations, soil characteristics, analyte, and duration of exposure, and that accumulation into earthworms may be a potential route of entry of PFAAs into terrestrial foodwebs.