Inhalation exposure to fluorotelomer alcohols yield perfluorocarboxylates in human blood?

Silicone Wristbands as a Personal Passive Sampler to Evaluate Indoor Exposure to Volatile and Non-volatile PFASs

Exposure to per- and polyfluoroalkyl substances (PFASs) primarily occurs via consumption of contaminated drinking water and food; however, individuals can also be exposed dermally and via inhalation indoors. This study developed an analytical method for measuring volatile PFASs in silicone wristbands and used them to assess personal exposure in a Midwestern community (n = 87). Paired samples of blood and wristbands were analyzed for PFASs using LC-MS/MS and GC-HRMS to monitor both non-volatile and volatile PFASs. The most frequently detected PFASs in wristbands were: 6:2 diPAP, 6:2 FTOH, MeFOSE and EtFOSE. Females had a 4-fold higher exposure to 6:2 diPAP compared to males and age-dependent differences in exposure to 6:2 FTOH, MeFOSE and EtFOSE were observed. Exposure to MeFOSE and EtFOSE differed based on the average time spent in the home. Frequently detected PFASs in blood were: PFOA, PFOS, PFHxS, PFHpS, and N-MeFOSAA. A strong correlation was found between MeFOSE in the wristbands and N-MeFOSAA in serum (rs = 0.90, p-value <0.001), suggesting exposure to this PFAS was primarily via inhalation and dermal exposure. These results demonstrate that wristbands can provide individual level data on exposure to some polyfluoroalkyl precursors present indoors that reflect serum levels of their suspected biotransformation products.

Analysis of Legacy and Novel Neutral Per- and Polyfluoroalkyl Substances in Soils from an Industrial Manufacturing Facility

Per- and polyfluoroalkyl substances (PFASs) have been detected in an array of environmental media due to their ubiquitous use in industrial and consumer products as well as potential release from fluorochemical manufacturing facilities. During their manufacture, many fluorotelomer (FT) facilities rely on neutral intermediates in polymer production including the FT-alcohols (FTOHs). These PFAS are known to transform to the terminal acids (perfluoro carboxylic acids; PFCAs) at rates that vary with environmental conditions. In the current study on soils from a FT facility, we employed gas chromatography coupled with conventional- and high-resolution mass spectrometry (GC-MS and GC-HRMS) to investigate the profile of these precursor compounds, the intermediary secondary alcohols (sFTOHs), FT-acrylates (FTAcr), and FT-acetates (FTAce) in soils around the former FT-production facility. Of these precursors, the general trend in detection intensity was [FTOHs] > [sFTOHs] > [FTAcrs], while for the FTOHs, homologue intensities generally were [12:2 FTOH] > [14:2 FTOH] > [16:2 FTOH] > [10:2 FTOH] > [18:2 FTOH] > [20:2 FTOH] > [8:2 FTOH] ∼ [6:2 FTOH]. The corresponding terminal acids were also detected in all soil samples and positively correlated with the precursor concentrations. GC-HRMS confirmed the presence of industrial manufacturing byproducts such as FT-ethers and FT-esters and aided in the tentative identification of previously unreported dimers and other compounds. The application of GC-HRMS to the measurement and identification of precursor PFAS is in its infancy, but the methodologies described here will help refine its use in tentatively identifying these compounds in the environment.

A systems toxicology approach for identification of disruptions in cholesterol homeostasis after aggregated exposure to mixtures of perfluorinated compounds in humans

Per- and polyfluoroalkyl substances (PFAS) are used in various household and industrial products. In humans, positive associations were reported between PFAS, including perfluorsulfonic acid and perfluorooctanoic acid, and cholesterol, a cardiometabolic risk factor. Animal studies show the opposite. Human-centered approaches are needed to better understand the effects of PFAS mixtures on cholesterol. Here, a systems toxicology approach is described, using a gene-centered cholesterol biokinetic model. PFAS exposure-gene expression relations from published data were introduced into the model. An existing PFAS physiologically based kinetic model was augmented with lung and dermal compartments and integrated with the cholesterol model to enable exposure-effect modeling. The final model was populated with data reflecting lifetime mixture exposure from: tolerable weekly intake values; the environment; high occupational exposures (ski waxing, PFAS industry). Results indicate that low level exposures (tolerable weekly intake, environmental) did not change cholesterol. In contrast, occupational exposures clearly resulted in internal PFAS exposure and disruption of cholesterol homeostasis, largely in line with epidemiological observations. Despite model limitations (eg, dynamic range, directionality), changes in cholesterol homeostasis were predicted for ski waxers, hitherto unknown from epidemiological studies. Here, future studies involving lipid metabolism could improve risk assessment.

Respiratory Exposure to Highly Fluorinated Chemicals via Application of Ski Wax and Related Health Effects

PURPOSE

Waxes containing per- and polyfluoroalkyl substances (PFAS) are applied to the base of skis and snowboards ("skis") to reduce friction with the snow surface and improve glide. PFAS exposure can adversely impact cardiometabolic, thyroid, liver, kidney, reproductive, and immune health and are associated with increased risk of certain cancers. In the present review, we summarize the state of the science on PFAS exposure from fluorinated ski wax use, including acute respiratory health effects and PFAS concentrations in biological and environmental media collected from ski waxing settings.

RECENT FINDINGS

Perfluoroalkyl carboxylic acid (PFCA) concentrations in serum and air collected from professional wax technicians and the rooms where waxes are applied are among the highest of any occupation investigated to date, including the fluorochemical industry. High airborne concentrations of fluorotelomer alcohols contribute to high body burdens of certain PFCAs among ski waxers. Fluorinated ski waxes are a significant source of PFAS exposure for people waxing skis and/or spending time in areas where waxing occurs. We highlight recommendations for future research, policy, and technologies needed to address PFAS exposures from fluorinated wax use.

Measurement of fluorotelomer alcohols based on solid phase microextraction followed by gas chromatography-mass spectrometry and its application in solid waste study

This work developed a method based on solid phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS) for the measurement of fluorotelomer alcohols (FTOHs) in gas samples. The method quantification limit (MQL) is 6-7 ng/L for 6:2 fluorotelomer alcohols (6:2 FTOH) and 8:2 fluorotelomer alcohols (8:2 FTOH). In contrast to common methods such as thermal desorption combined with GC-MS, it needs neither pre-concentration equipment nor large sample volume. The extraction-evaporation-GC/MS is commonly used in literature for FTOHs measurement in solids samples. We developed a method to measure FTOHs in solid samples by adding solvent extraction prior to headspace SPME-GC/MS. The extraction-headspace SPME-GC/MS method has a quantification limit of 40-43 ng per gram for 6:2 FTOH and 8:2 FTOH in solid samples. This is comparable to the MQLs for the extraction-evaporation-GC/MS method. Removing the solvent evaporation step decreased the risk of contamination and loss of analytes. The developed methods were successfully used in three examples of solid waste study: 1) measuring 6:2 FTOH and 8:2 FTOH above the MQL in gas emissions from a closed landfill, 2) finding 6:2 FTOH above MQL in 9 of 31 solid consumer products, and 3) finding that the release of 6:2 FTOH in simulated landfills containing popcorn bags was linear at a rate of 3.15 ng/g popcorn bags-day and that partial 6:2 FTOH was from the hydrolysis of precursors.

Removal of perfluorooctanoic acid (PFOA) in the liquid culture of Phanerochaete chrysosporium

Perfluorooctanoic acid (PFOA) is becoming a concern due to its persistence, bioaccumulation, and potential harmful effects on humans and the environment. In this study, the fungus Phanerochaete chrysosporium (P. chrysosporium) was used to remove the PFOA in liquid culture system. The results showed that the average activities of laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP) enzymes secreted by P. chrysosporium were 0.0003 U/mL, 0.013 U/mL, and 0.0059 U/mL, respectively, during the incubation times of 0-75 days. The pH of 3 and incubation time of 45-55 days were the optimum parameters for the three enzymes activities. The enzyme activities in P. chrysosporium incubation system were firstly inhibited by adding PFOA and then they were enhanced after 14 days. The maximum removal efficiency of PFOA (69.23%) was achieved after 35 days in P. chrysosporium incubation system with an initial PFOA concentration of 0.002 mM and no veratryl alcohol (VA). Adsorption was not a main pathway for PFOA removal and the PFOA adsorbed in fungi mycelial mat accounted for merely 1.91%. The possible products of PFOA contained partially fluorinated aldehyde, alcohol, and aromatic ring. These partially fluorinated compounds might result from PFOA degradation via a combination of cross-coupling and rearrangement of free radicals.

Rapid, efficient, and green analytical technique for determination of fluorotelomer alcohol in water by stir bar sorptive extraction

Fluorotelomer alcohols (FTOHs) are one of the major classes of per- and polyfluoroalkyl substances (PFAS). Due to their potential toxicity, persistence, and ubiquitous presence in the environment, some common PFAS are voluntarily phased out; while FTOHs are used as alternatives to conventional PFAS. FTOHs are precursors of perfluorocarboxylic acids (PFCAs) and therefore they are commonly detected in water matrices, which eventually indicate PFAS contamination in drinking water supplies and thus a potential source of human exposure. Even though studies have been conducted nationwide to evaluate the degree of FTOHs in the water environment, robust monitoring is lacking because of the unavailability of simple and sustainable analytical extraction and detection methods. To fill the gap, we developed and validated a simple, rapid, minimal solvent use, no clean-up, and sensitive method for the determination of FTOHs in water by stir bar sorptive extraction (SBSE) coupled with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Three commonly detected FTOHs (6:2 FTOH, 8:2 FTOH, and 10:2 FTOH) were selected as the model compounds. Factors such as extraction time, stirring speed, solvent composition, salt addition, and pH were investigated to achieve optimal extraction efficiency. This "green chemistry" based extraction provided good sensitivity and precision with low method limits of detection ranging from 2.16 ng/L to 16.7 ng/L and with an extraction recovery ranging 55%-111%. The developed method were tested on tap water, brackish water, and wastewater influent and effluent. 6:2 FTOH and 8:2 FTOH were detected in two wastewater samples at 78.0 and 34.8 ng/L, respectively. This optimized SBSE-TD-GC-MS method will be a valuable alternative to investigate FTOHs in water matrices.

Occupational exposure to per- and polyfluoroalkyl substances: a scope review of the literature from 1980-2021

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of chemicals that have been integrated into a wide variety of industrial processes and consumer products since the 1950s. Due to their profuse usage and high persistence in human serum, understanding workplace exposures to PFAS is critical.

OBJECTIVE

We aimed to characterize the PFAS exposure profiles of relevant occupational populations, elucidate trends in the PFAS exposure characterization process, and identify major research gaps that remain within the occupational PFAS exposure literature.

METHODS

A systematic search of four literature databases for peer-reviewed articles published between 1980 and 2021 on PFAS exposure in occupational settings was conducted.

RESULTS

Of the 2574 articles identified, 92 met the inclusion criteria. Fluorochemical workers were the target population in most early exposure assessment research; however, studies conducted within the last 10 years have evaluated a wider range of occupational populations and settings. The highest exposures were reported in fluorochemical workers, but, in comparison to reference populations, one or more PFAS were elevated in most workers and in most workplaces that were assessed. PFAS was most frequently assessed in worker serum using a discrete analytical panel of PFAS, with earlier studies restricted to a few long-alkyl chain PFAS while more recent studies have included more expansive panels due to more robust methods.

SIGNIFICANCE

Characterization of occupational exposure to PFAS is limited but expanding. Current analytical methods are not robust enough to fully capture the potential range of PFAS present across different workers and workplaces. While exposures to PFAS for certain occupational groups have been studied in detail, exposure information for other occupational groups with high potential for exposure are limited. This review highlights substantial findings and major research gaps within the occupational literature.

Embryonic 6:2 FTOH exposure causes reproductive toxicity by disrupting the formation of the blood-testis barrier in offspring mice

Previous studies have revealed nephrotoxicity, hepatotoxicity, subchronic developmental and reproductive toxicity in rats exposed to fluorotelomer alcohol (FTOH). However, the effects of embryonic 6:2 FTOH exposure on the reproductive system of offspring mice remain unclear. The purpose of this study is to explore the reproductive toxic effects of embryonic 6:2 FTOH exposure on offspring male mice and the related molecular mechanisms. Therefore, the pregnant mice were given corn oil or 6:2 FTOH by gavage from gestational days 12.5-21.5. The results demonstrated that embryonic 6:2 FTOH exposure resulted in disrupted testicular structure, low expression of tight junction protein between Sertoli cells (SCs), impaired blood-testis barrier (BTB) formation and maturation, reduced sperm viability and increased malformation, and induced testicular inflammation in the offspring of mice. Further in vitro studies showed that 6:2 FTOH treatment upregulated MMP-8 expression by activating AKT/NF-κB signaling pathway, which in turn enhanced occludin cleavage leading to the disruption of SCs barrier integrity. In summary, this study demonstrated that 6:2 FTOH exposure caused reproductive dysfunction in male offspring through disruption of BTB, which provided new insights into the effects of 6:2 FTOH exposure on the offspring.

Assessment of perfluorohexane sulfonic acid (PFHxS)-related compounds degradation potential: Computational and experimental approaches

Perfluorohexane sulfonic acid (PFHxS) and PFHxS-related compounds are listed in Annex A of the Stockholm Convention without specific exemptions. Substances that potentially degrade to PFHxS are considered as their related compounds. Unfortunately, the degradation behavior of PFHxS precursors, an important basis for the corresponding chemical regulation, remains unclear. Herein, based on the hypothesis that bond dissociation enthalpy (BDE) is the determining factor for the degradation of PFHxS precursors, the BDE of PFHxS-related precursors to produceC6F13SO2-groups was calculated. In addition, quantitative structure-activity relationship models based on partial least squares, partial least squares discrimination analysis, and support vector machine algorithms were developed to predict the BDE of 48 PFHxS precursors and distinguish the precursors with different degradation potential. Subsequent photodegradation experiments demonstrated that the order of degradation rates was consistent with that predicted by theoretical models. Importantly, perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid, and not PFHxS, were detected as the degradation products of potential PFHxS precursors. Sulfonamides, phenyl unit, and other radicals in the non-nucleus part of PFHxS precursors were identified as the critical molecular segments that affect their degradation potential. Ultimately, by comparing BDE values, it was theoretically speculated that PFHxS related compounds exhibit a greater potential to generate PFHxA than PFHxS. Results in this study indicated for the first time that not all the compounds containing C6F13SO2- groups were guaranteed to degrade into PFHxS under natural conditions.

Neutral Per- and Polyfluoroalkyl Substances, Butyl Carbitol, and Organic Corrosion Inhibitors in Aqueous Film-Forming Foams: Implications for Vapor Intrusion and the Environment

Per- and polyfluoroalkyl substances (PFAS), butyl carbitol, and corrosion inhibitors are components of aqueous film-forming foams (AFFFs). Volatile (neutral) fluorotelomerization (FT)- and electrochemical fluorination (ECF)-based PFAS, butyl carbitol, and organic corrosion inhibitors were quantified in 39 military specification (MilSpec), non-MilSpec, and alcohol resistant-AFFF concentrates (undiluted) from 1974 to 2010. Fluorotelomer alcohols were found only in FT-based AFFFs and N-methyl- and N-ethyl-perfluoroalkyl sulfonamides, and sulfonamido ethanols were found only in ECF-based AFFFs. Neutral PFAS and benzotriazole, 4-methylbenzotriazole, and 5-methybenzotriazole occurred at mg/L levels in the AFFFs, while butyl carbitol occurred at g/L levels. Neutral PFAS concentrations in indoor air due to vapor intrusion of a nearby undiluted AFFF release are estimated to be anywhere from 2 to >10 orders of magnitude higher than documented background indoor air concentrations. Estimated butyl carbitol and organic corrosion inhibitor concentrations were lower than and comparable to indoor concentrations recently measured, respectively. The wide range of neutral PFAS concentrations and Henry's law constants indicate that field, soil-gas measurements are needed to validate the estimations. Co-discharged butyl carbitol likely contributes to oxygen depletion in AFFF-impacted aquifers and may hinder the natural PFAS aerobic biotransformation. Organic corrosion inhibitors in AFFFs indicate that these are another source of corrosion inhibitors in the environment.

Characterization of Per- and Polyfluorinated Alkyl Substances Present in Commercial Anti-fog Products and Their In Vitro Adipogenic Activity

Anti-fog sprays and solutions are used on eyeglasses to minimize the condensation of water vapor, particularly while wearing a mask. Given their water-repellent properties, we sought to characterize per- and polyfluorinated alkyl substance (PFAS) compounds in four anti-fog spray products, five anti-fog cloth products, and two commercial fluorosurfactant formulations suspected to be used in preparing anti-fog products. Fluorotelomer alcohols (FTOHs) and fluorotelomer ethoxylates (FTEOs) were detected in all products and formulations. While 6:2 FTOH and the 6:2 FTEO polymeric series were predominant, one anti-fog cloth and one formulation contained 8:2, 10:2, 12:2, 14:2, and 16:2 FTOH and FTEO polymeric series. PFAS concentrations varied in samples and were detected at levels up to 25,000 μg/mL in anti-fog sprays and 185,000 μg (g cloth)-1 in anti-fog cloth products. The total organic fluorine (TOF) measurements of anti-fog products ranged from 190 to 20,700 μg/mL in sprays and 44,200 to 131,500 μg (g cloth)-1 in cloths. Quantified FTOHs and FTEOs accounted for 1-99% of TOF mass. In addition, all four anti-fog sprays and both commercial formulations exhibited significant cytotoxicity and adipogenic activity (either triglyceride accumulation and/or pre-adipocyte proliferation) in murine 3T3-L1 cells. Results suggest that FTEOs are a significant contributor to the adipogenic activity exhibited by the anti-fog sprays. Altogether, these results suggest that FTEOs are present in commercial products at toxicologically relevant levels, and more research is needed to fully understand the health risks from using these PFAS-containing products.

Environmental Source Tracking of Per- and Polyfluoroalkyl Substances within a Forensic Context: Current and Future Techniques

The source tracking of per- and polyfluoroalkyl substances (PFASs) is a new and increasingly necessary subfield within environmental forensics. We define PFAS source tracking as the accurate characterization and differentiation of multiple sources contributing to PFAS contamination in the environment. PFAS source tracking should employ analytical measurements, multivariate analyses, and an understanding of PFAS fate and transport within the framework of a conceptual site model. Converging lines of evidence used to differentiate PFAS sources include: identification of PFASs strongly associated with unique sources; the ratios of PFAS homologues, classes, and isomers at a contaminated site; and a site's hydrogeochemical conditions. As the field of PFAS source tracking progresses, the development of new PFAS analytical standards and the wider availability of high-resolution mass spectral data will enhance currently available analytical capabilities. In addition, multivariate computational tools, including unsupervised (i.e., exploratory) and supervised (i.e., predictive) machine learning techniques, may lead to novel insights that define a targeted list of PFASs that will be useful for environmental PFAS source tracking. In this Perspective, we identify the current tools available and principal developments necessary to enable greater confidence in environmental source tracking to identify and apportion PFAS sources.

PFAS Exposure Pathways for Humans and Wildlife: A Synthesis of Current Knowledge and Key Gaps in Understanding

We synthesize current understanding of the magnitudes and methods for assessing human and wildlife exposures to poly- and perfluoroalkyl substances (PFAS). Most human exposure assessments have focused on 2 to 5 legacy PFAS, and wildlife assessments are typically limited to targeted PFAS (up to ~30 substances). However, shifts in chemical production are occurring rapidly, and targeted methods for detecting PFAS have not kept pace with these changes. Total fluorine measurements complemented by suspect screening using high-resolution mass spectrometry are thus emerging as essential tools for PFAS exposure assessment. Such methods enable researchers to better understand contributions from precursor compounds that degrade into terminal perfluoroalkyl acids. Available data suggest that diet is the major human exposure pathway for some PFAS, but there is large variability across populations and PFAS compounds. Additional data on total fluorine in exposure media and the fraction of unidentified organofluorine are needed. Drinking water has been established as the major exposure source in contaminated communities. As water supplies are remediated, for the general population, exposures from dust, personal care products, indoor environments, and other sources may be more important. A major challenge for exposure assessments is the lack of statistically representative population surveys. For wildlife, bioaccumulation processes differ substantially between PFAS and neutral lipophilic organic compounds, prompting a reevaluation of traditional bioaccumulation metrics. There is evidence that both phospholipids and proteins are important for the tissue partitioning and accumulation of PFAS. New mechanistic models for PFAS bioaccumulation are being developed that will assist in wildlife risk evaluations. Environ Toxicol Chem 2021;40:631-657. © 2020 SETAC.

Regulating PFAS as a Chemical Class under the California Safer Consumer Products Program

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of manmade chemicals containing at least one fully fluorinated carbon atom. The widespread use, large number, and diverse chemical structures of PFAS pose challenges to any sufficiently protective regulation, emissions reduction, and remediation at contaminated sites. Regulating only a subset of PFAS has led to their replacement with other members of the class with similar hazards, that is, regrettable substitutions. Regulations that focus solely on perfluoroalkyl acids (PFAAs) are ineffective, given that nearly all other PFAS can generate PFAAs in the environment.

OBJECTIVES

In this commentary, we present the rationale adopted by the State of California's Department of Toxic Substances Control (DTSC) for regulating PFAS as a class in certain consumer products.

DISCUSSION

We at the California DTSC propose regulating certain consumer products if they contain any member of the class of PFAS because: a) all PFAS, or their degradation, reaction, or metabolism products, display at least one common hazard trait according to the California Code of Regulations, namely environmental persistence; and b) certain key PFAS that are the degradation, reaction or metabolism products, or impurities of nearly all other PFAS display additional hazard traits, including toxicity; are widespread in the environment, humans, and biota; and will continue to cause adverse impacts for as long as any PFAS continue to be used. Regulating PFAS as a class is thus logical, necessary, and forward-thinking. This technical position may be helpful to other regulatory agencies in comprehensively addressing this large class of chemicals with common hazard traits. https://doi.org/10.1289/EHP7431.

Fluorotelomer Alcohols' Toxicology Correlates with Oxidative Stress and Metabolism

Fluorotelomer alcohols (FTOHs) are widely used as industrial raw materials due to their unique hydrophobic and oleophobic properties. However, because of accidental exposure to products containing FTOHs or with the widespread use of FTOHs, they tend to contaminate the water and the soil. There are reports demonstrating that FTOHs can cause various harmful effects in animals and humans (for example, neurotoxicity, hepatotoxicity, nephrotoxicity, immunotoxicity, endocrine-disrupting activity, and developmental and reproductive toxicities). Oxidative stress is related to a variety of toxic effects induced by FTOHs. To date, few reviews have addressed the relationship between the toxicity of FTOHs and oxidative stress. This article summarises research demonstrating that the toxicity induced by FTOHs correlates with oxidative stress and metabolism. Furthermore, during the metabolic process of FTOHs, a number of cytochrome P450 enzymes (CYP450) are involved and many metabolites are produced by these enzymes, which can induce oxidative stress. This is also reviewed.

Levels of per- and polyfluoroalkyl substances (PFAS) in ski wax products on the market in 2019 indicate no changes in formulation

In the summer of 2019, eleven of the best-selling fluorinated ski wax products were purchased from one of Norway's largest sports stores and soon after analysed for a suite of 26 per- and polyfluoroalkyl substances (PFAS). The waxes were shown to contain a wide range of perfluoroalkyl acids, including perfluoroalkyl carboxylic acids with up to 25 carbons. Of particular concern was the finding that perfluorooctanoic acid (PFOA) levels in nine of the eleven ski lubrication products analysed were above the EU limit values of 25 ng g^-1, which came into force on 4^th July 2020. The ski wax with the highest PFOA levels had a concentration that was 1215 times higher than the EU restrictions. Although some of the ski wax manufacturers have indicated that they have switched to formulations that contain chemistries based on shorter perfluoroalkyl chains, the analytical results show that this is not the case.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

Tissue distribution and bioaccumulation of 8:2 fluorotelomer alcohol and its metabolites in pigs after oral exposure

The tissue distribution and bioaccumulation of 8:2 fluorotelomer alcohol (8:2 FTOH) were evaluated in pigs after oral exposure of a dose of 5 mg/kg.b.w.d. for 7 d. The bioaccumulation of 8:2 FTOH and its metabolites showed significant differences among the various tissues. The parent compound was quickly depleted, and the main metabolites perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA), and 3-perfluoroheptyl propanoic acid (7:3 FTCA) were detected in all tissues examined. The relative elimination half-life (T_1/2re) calculated by compound concentration of 7:3 FTCA and PFOA was longest in kidney tissue (8.60 and 23.9 d, respectively), while their absolute elimination half-life (T_1/2ab) of 7:3 FTCA and PFOA calculated by compound amount was longest in kidney tissue (10.41 and 64.1 d, respectively). The T_1/2re and T_1/2ab for PFHpA was longest in heart tissue (19.3 d and 30.26 d, respectively).The accumulated PFOA in kidney and liver tissues was still above the detection limit (LOD) at 21 d postdosing. These results indicate that PFOA and the kidneys are the ideal biomonitoring marker and target tissue, respectively, for 8:2 FTOH pollution. The T_1/2 values of the main metabolites were of long duration compared to the growth cycle of farmed pigs (approximately 180 d) before slaughter; therefore, pigs contaminated with 8:2 FTOH present a potential risk to humans.

Nontargeted identification of per- and polyfluoroalkyl substances in human follicular fluid and their blood-follicle transfer

The female reproductive toxicity of per- and polyfluoroalkyl substances (PFAS) has raised concerns, but knowledge about their human preconception exposure is limited. In this study, 15 emerging PFAS were identified in follicular fluid samples from healthy women by using high-resolution mass spectrometry, and Cl-substituted perfluoroalkyl ether sulfonates (Cl-PFESAs) including 4:2, 5:2, 6:2, and 8:2 Cl-PFESAs, 4:4 C₈ perfluoroalkyl ether sulfonate (PFESA), C₈ perfluoroalkyl ether carboxylate (PFECA), and C₈ polyether PFECA (Po-PFECA) were detected in over 50% of 28 follicular fluid samples. Ten legacy PFAS were also detected, and the geometric mean concentration of PFOS was the highest (4.82 ng/mL), followed by PFOA (4.60 ng/mL), 6:2 Cl-PFESA (1.09 ng/mL), PFHxS (0.515 ng/mL), PFNA (0.498 ng/mL), and C₈ PFECA (0.367 ng/mL). The blood-follicle transfer efficiencies for PFCAs decreased with increasing chain length (0.96 for PFHpA, 0.56 for PFTriDA), and the transfer efficiencies of C₈ PFECA (0.78) was significantly higher than that of PFOA (0.76). The transfer efficiencies of 4:2 Cl-PFESA (0.73), 6:2 Cl-PFESA (0.75) and 8:2 Cl-PFESA (0.91) were significantly higher than that (0.70) of PFOS (p = 0.028, 0.026 and 0.002, respectively). This study constitutes the first report of the human oocyte exposure to emerging PFAS and their blood-follicle transfer abilities.

Characterizing biopersistence potential of the metabolite 5:3 fluorotelomer carboxylic acid after repeated oral exposure to the 6:2 fluorotelomer alcohol

Our previous report on pharmacokinetic (PK) evaluation of 6:2 fluorotelomer alcohol (6:2 FTOH) examined the biopersistence potential of its metabolites based on data published from single inhalation and occupational 6:2 FTOH exposure studies. We calculated internal exposure estimates of three key metabolites of 6:2 FTOH, of which 5:3 fluorotelomer carboxylic acid (5:3 acid) had the highest internal exposure and the slowest clearance. No oral repeated 6:2 FTOH exposure data were available at the time to fully characterize the biopersistence potential of the metabolite 5:3 acid. We recently received additional data on 6:2 FTOH and 5:3 acid, which included a 90-day toxicokinetic study report on repeated oral 6:2 FTOH exposure to rats. We reviewed the study and analyzed the reported 5:3 acid concentrations in plasma, liver, and fat using one-compartment PK modeling and calculated elimination rate constants (k_el), elimination half-lives (t_1/2) and times to steady state (t_ss) of 5:3 acid at three 6:2 FTOH doses. Our results showed that t_ss of 5:3 acid in plasma and evaluated tissues were approximately close to 1 year, such that the majority of highest values were observed at the lowest 6:2 FTOH dose, indicating its association with the biopersistence of 6:2 FTOH. The results of our PK analysis are the first to characterize biopersistence potential of the 5:3 acid after repeated oral exposure to the parent compound 6:2 FTOH based on steady state PK parameters, and therefore, may have an impact on future study designs when conducting toxicity assays for such compounds.

Perfluoroalkyl substances in groundwater and home-produced vegetables and eggs around a fluorochemical industrial park in China

High-level contaminations of perfluoroalkyl substances (PFASs) were determined in both surface water and groundwater around a fluorochemical industrial park (FIP) in Fuxin, China, over the past few years. Yet little is known about whether groundwater PFAS contaminations in Fuxin could be introduced into home-produced vegetables and eggs in local residences via the application of groundwater for the irrigation or feeding purposes. In the present study, ten PFAS analytes were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to investigate the extent of PFAS contaminations in the groundwater, soil, and home-produced vegetable and egg samples derived from Fuxin. As the predominant PFAS contaminants, perfluorobutane sulfonate (PFBS) and perfluorooctanoic acid (PFOA) were observed in groundwater beneath the Fuxin FIP with the maximum concentrations of 21.2 and 2.51 µg/L, respectively, which were 24-fold and 5-fold higher individually compared to those reported previously. Both of them were also higher than the updated health advisories for PFBS and PFOA in drinking water issued by the Minnesota Department of Health and the US Environmental Protection Agency. In addition, short-chain PFASs involving perfluorobutanoic acid (PFBA) and PFBS were found to be the major contaminants in both home-produced vegetables and eggs from the residential gardens around the FIP. Statistically significant relationships were determined between the levels of PFBA, PFOA, and PFBS in local groundwater and those observed in home-produced vegetables (p = 0.003, p = 0.025, and p < 0.001), suggesting potential entry of those PFAS contaminants into home-produced vegetables via irrigation with groundwater beneath the FIP.

Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Internal exposure-based pharmacokinetic evaluation of potential for biopersistence of 6:2 fluorotelomer alcohol (FTOH) and its metabolites

Polyfluorinated compounds (PFCs) are authorized for use as greaseproofing agents in food contact paper. As C8-PFCs (8-carbons) are known to accumulate in tissues, shorter-chain C6-PFCs (6-carbons) have replaced C8-PFCs in many food contact applications. However, the potential of C6-PFCs for human biopersistence has not been fully evaluated. For the first time, we provide internal exposure estimates to key metabolites of 6:2 fluorotelomer alcohol (6:2 FTOH), a monomeric component of C6-PFCs, to extend our understanding of exposure beyond estimates of external exposure. Pharmacokinetic data from published rat and human studies on 6:2 FTOH were used to estimate clearance and area under the curve (AUC) for its metabolites: 5:3 fluorotelomer carboxylic acid (5:3 A), perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA). Internal exposure to 5:3 A was the highest of evaluated metabolites across species and it had the slowest clearance. Additionally, 5:3 A clearance decreased with increasing 6:2 FTOH exposure. Our analysis provides insight into association of increased internal 5:3 A exposure with high biopersistence potential of 6:2 FTOH. Our results identify 5:3 A as an important biomarker of internal 6:2 FTOH exposure for use in biomonitoring studies, and are potentially useful for toxicological assessment of chronic dietary 6:2 FTOH exposure.

PFCA uptake and translocation in dominant wheat species (Triticum aestivum L.)

The comparative uptake of four perfluorinated carboxylic acids (PFCAs) by wheat (Triticum aestivum L.) grown in nutrient solution was investigated. Wheat is the main food crop in northern China and may become a potential pathway of human exposure to these PFCAs. The uptake of four PFCAs from water at a fixed concentration (1 μg/mL) increased over time, approaching a steady state, and except for the short-chain perfluorobutanoic acid, most of the total mass of each of the PFCAs taken up by wheat was found to be at the root. The root concentration factor (RCF) and shoot/root concentration factor (SRCF) were calculated, and with the increase in carbon chain length, the RCFs increased but SRCFs decreased, which indicated that long-chain PFCAs had stronger root uptake and weaker translocation capacities than short-chain PFCAs. In addition, pH could obviously impact the uptake of four PFCAs in the roots and shoots of wheat, and the highest concentrations were found at pH = 7 when the pH increased from 4 to 10.

Detection, Occurrence, and Fate of Fluorotelomer Alcohols in Municipal Wastewater Treatment Plants

Fluorotelomer alcohols (FTOHs) are the most well-known precursors of perfluoroalkyl carboxylic acids (PFCAs), but limited information is available on their occurrence and fate in municipal wastewater treatment plants (WWTPs). The occurrence of FTOHs was investigated in influent, secondary effluent, and sludge of 12 municipal WWTPs in nine cities of China. FTOHs were detected in all WWTPs, and 8:2 FTOH was the predominant congener, with concentrations of 2.10-11.0 ng/L, 3.05-12.4 ng/L, and 0.36-1.91 ng/g dry weight in the influent, secondary effluent, and sludge, respectively. Relatively high proportions of long-chain FTOHs (C_10-16) were mainly detected in sludge samples. The mass balance of FTOHs and PFCAs in one of the WWTPs with an anaerobic-anoxic-oxic process was further explored. The decrease of mass loads was observed for 4:2 FTOH (mass change percentage: 21 ± 3.3%), 8:2 FTOH (22 ± 1.5%), and 10:2 FTOH (29 ± 7.3%) through aerobic treatment, while the increase of mass loads was observed for 12 PFCAs from 18 ± 16% (perfluorononanoic acid) to 165 ± 15% (perfluorobutyric acid)), suggesting the potential biotransformation of FTOHs to PFCAs in the aerobic unit. This work provides the first report on the occurrence of FTOHs in sludge samples of municipal WWTPs and their mass balance and highlights a new emission route to environment via WWTPs.

Human exposure to perfluoroalkyl substances near a fluorochemical industrial park in China

Severe perfluoroalkyl substance (PFAS) contaminations have been observed in both surface water and groundwater in the vicinity of Fuxin, China, over the past years, attributing to the fast-growing fluorochemical industries locally. However, little is known about the overall daily intake of PFAS contaminations by Fuxin residents recently. In the present study, ten target PFAS analytes in the blood serum samples collected from 100 non-occupationally exposed healthy residents in Fuxin, with an average age of 47.6 years, together with 14 drinking water samples obtained from the public water system (PWS) of Fuxin were analyzed via high-performance liquid chromotography-tandem mass spectrometry (HPLC-MS/MS). As the dominant PFAS contaminant, the serum concentrations of perfluorooctanoic acid (PFOA) in Fuxin residents ranged between <0.05 and 160 ng/mL, with a median concentration of 9.4 ng/mL, which was higher than those reported previously for Fuxin and other areas worldwide. In drinking water samples, PFOA had a median value of 8.5 ng/L, ranging from 7.7 to 8.8 ng/L. Based upon the simplified one-compartment pharmacokinetic model, the total daily intake of PFOA for individuals residing in Fuxin ranged from 0.30 to 1.76 ng/kg bw/day, with a median of 0.79 ng/kg bw/day; furthermore, daily consumption of drinking water from the PWS in Fuxin appeared to contribute 35% of overall PFOA burden in local residents, which was approximately 3-fold higher compared to that estimated for Fuxin residents in 2009.

Influence of salinity and temperature on uptake of perfluorinated carboxylic acids (PFCAs) by hydroponically grown wheat (Triticum aestivum L.)

Perfluoroalkyl substances (PFASs) have recently attracted increasing concerns due to their ubiquitous existence, adverse effects and persistence in environment. This study employed four perfluorinated carboxylic acids (PFCAs) to examine effects of salinity and temperature on the PFAS uptake in wheat, one of the major crops in the North China Plain. Wheat plants were grown in the spiked-PFCA hydroponic culture system at different salinities and temperatures. As expected, salinity and temperature significantly impacted the root uptake and translocation of wheat to four PFCAs, and the concentrations for each of PFCAs in wheat root and shoot increased with increasing salinity and temperature, respectively. PFCA concentrations at high salinity or high temperature were up to thrice those found at low salinity or low temperature. Except for perfluorobutanoic acid, the amount of PFCAs in root was always higher than that in shoot at the ranges of salinity and temperature tested. Additionally salinity and temperature were also capable of influencing the transfer factors (TFs) of four PFCAs, and significant increase was observed in the TFs in response to the increases in salinity and temperature.

Ubiquitous Occurrence of Fluorotelomer Alcohols in Eco-Friendly Paper-Made Food-Contact Materials and Their Implication for Human Exposure

The occurrence of fluorotelomer alcohols (FTOHs) was investigated in 94 food-contact materials (FCMs). We detected 6:2 FTOH (<0.60-1110 ng/g), 8:2 FTOH (<0.40-8490 ng/g), and 10:2 FTOH (<0.02-9350 ng/g) in most FCM samples, and four longer-chain C14-20 FTOHs were, for the first time, identified in FCMs with relatively high concentrations (<0.02-8450 ng/g for 12:2 FTOH, <0.02-1640 ng/g for 14:2 FTOH, <0.02-372 ng/g for 16:2 FTOH, and <0.02-130 ng/g for 18:2 FTOH). There were three typical profiles of FTOHs that were dominated by 6:2 FTOH (95.6 ± 8.1% in 9 FCMs), 8:2 FTOH (50.9 ± 20.8% in 22 FCMs), and 10:2 FTOH (44.5 ± 20.9% in 30 FCMs), indicating the congener-specific usage of FTOHs for different commercial purposes. All nine detectable FCMs produced in the United States were dominated by 6:2 FTOH, which was significantly different from those produced in China. The median concentration of total FTOHs in eco-friendly paper tableware was 2990 ng/g, which was lower than in popcorn bags (18 200 ng/g) but much higher than other FCMs (<0.55-38.7 ng/g). FTOHs could migrate from paper bowls, with migration efficiencies of 0.004-0.24% into water, 0.004-0.24% into 10% ethanol, 0.009-2.79% into 30% ethanol, 0.06-13.0% into 50% ethanol (v/v) simulants, and 0.04-2.28% into oil. Migration efficiencies decreased with increasing carbon chain lengths of FTOHs.

Perfluoroalkyl acids in blood serum samples from children in Taiwan

Severe perfluoroalkyl acid (PFAA) contamination resulting from the fast-growing semiconductor, electrochemical, and optoelectronic industries has been determined in the river water in the vicinity of the Taipei area, Taiwan, during recent years. However, little is known about body burdens of the PFAA contaminations in local residents, especially children living in the Taipei area recently. In this study, ten target PFAA analytes consisted of three perfluorosulfonates (PFSAs) and seven perfluorocarboxylates (PFCAs) in the blood serum samples, collected from 225 healthy children with an average age of 13.6 years in the Taipei area from 2009 to 2010, were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). As the dominant PFAA contaminant in the blood serum samples from Taiwanese children, perfluorooctane sulfonate (PFOS) contributed 86% of all the target PFAA analytes, while the other nine analytes contributed less than 5% individually. PFOS showed the highest median up to 29 ng/mL, ranging from 0.03 to 148 ng/mL, which was higher than that observed in the serum samples collected from Taiwanese children between 2006 and 2008. Statistically, serum concentrations of perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and perfluorooctanoic acid (PFOA) had significantly positive correlations with ages of children (p < 0.05). Furthermore, serum PFBS, PFHxS, and PFOA concentrations in the male children were considerably higher than those in the female children (p = 0.049, p = 0.000, p = 0.000).

Highly elevated serum concentrations of perfluoroalkyl substances in fishery employees from Tangxun lake, china

Increasing production and use of per- and polyfluoroalkyl substances (PFASs) has been reported from China, and a few studies have shown there are subpopulations in China with high and increasing exposure to these chemicals. In this paper, we present a comprehensive exposure assessment of PFASs in fishery employees from Tangxun Lake, China. Exceptionally high serum concentrations of C4 to C12 PFASs were observed in fishery employees (n = 39, median perfluorooctanesulfonic acid (PFOS) 10 400 ng/mL) compared to a reference group from the same city (n = 9, median PFOS 18.7 ng/mL). On the basis of the comparison of different exposure pathways, it was concluded that contaminated fish from Tangxun Lake was the primary source of PFAS exposure to fishery employees, and there was a positive association between serum PFAS concentrations and time of employment in the fishery. PFOS isomer profiles in fishery employees showed a significantly higher proportion of linear PFOS (78.4%) compared to the background-exposed reference group (66.8%), reflecting the highly linear PFOS isomer profile (>90%) of lake fish. Median renal clearance rates (CLrenal) of C4 to C10 perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkanesulfonic acids (PFSAs) ranged from 0.020 to 16.5 mL/day/kg and 0.013 to 9.43 mL/day/kg, respectively. PFCAs with less than eight perfluoroalkyl carbons were primarily eliminated via urine, whereas other routes of excretion may have contributed to the elimination for long-chain PFCAs and PFSAs. Calculated daily PFOS exposures of fishery employees significantly exceeded tolerable daily intake limits, but clinical blood chemistry parameters were mostly within normal reference ranges. However, additional epidemiological studies are needed to address potential associations between PFAS exposure and health effects in the Tangxun Lake area.

Elimination kinetics of perfluorohexanoic acid in humans and comparison with mouse, rat and monkey

Major fluorinated chemical manufacturers have developed new short-chain per- and polyfluorinated substances with more favorable environmental, health and safety profiles. This study provides the first evaluation of the elimination half-life of perfluorohexanoic acid (PFHxA) from the blood of humans. PFHxA biomonitoring data were obtained from a recently published study of professional ski wax technicians. These data were analyzed to provide estimates of the apparent half-life of PFHxA from humans, and comparisons were made with kinetic studies of PFHxA elimination from mice, rats and monkeys. The apparent elimination half-life of PFHxA in highly exposed humans ranged between 14 and 49 d with a geomean of 32 d. The half-lives of PFHxA in mice, rats, monkeys and humans were proportional to body weight with no differences observed between genders, indicating similar volumes of distribution and similar elimination mechanisms among mammalian species. Compared to long-chain perfluoroalkyl acid analogs, PFHxA is rapidly cleared from biota. The consistent weight-normalized elimination half-lives for PFHxA in mammalian species indicates that results obtained from animal models are suitable for establishment of PFHxA benchmark dose and reference dose hazard endpoints for use in human risk assessments.

Estrogen-like response of perfluorooctyl iodide in male medaka (Oryzias latipes) based on hepatic vitellogenin induction

Using the in vivo male medaka model, we investigated the estrogen-like response of perfluorooctyl iodide (PFOI) which is a potential source of perfluorinated carboxylic acids. Using real-time quantitative polymerase chain reaction, the expression levels of related estrogenic genes including estrogenic receptor α (ERα), ERβ, vitellogenin I (VTG I), and VTG II in the livers of male medaka exposed to PFOI were analyzed. The results showed that PFOI upregulated the expression levels of the tested genes in a dose-dependent manner. VTG protein levels increased in both dose- and time-dependent manners due to PFOI exposure. The results suggested that PFOI is a potential estrogenic compound.

Detection of fluorotelomer alcohols in indoor environments and their relevance for human exposure

Fluorotelomer alcohols (FTOH) are important precursors of perfluorinated carboxylic acids (PFCA). These neutral and volatile compounds are frequently found in indoor air and may contribute to the overall human exposure to per- and polyfluorinated alkyl substances (PFAS). In this study air samples of ten workplace environments and a car interior were analysed. In addition, extracts and emissions from selected outdoor textiles were analysed in order to establish their potential contribution to the indoor levels of the above-mentioned compounds. Concentrations of FTOHs measured in air ranged from 0.15 to 46.8, 0.25 to 286, and 0.11 to 57.5ng/m(3) for 6:2, 8:2 and 10:2 FTOHs, respectively. The highest concentrations in air were identified in shops selling outdoor clothing, indicating outdoor textiles to be a relevant source of FTOH in indoor workplace environments. Total amounts of FTOH in materials of outdoor textiles accounted for <0.8-7.6, 12.1-180.9 and 4.65-105.7μg/dm(2) for 6:2, 8:2 and 10:2 FTOHs, respectively. Emission from selected textiles revealed emission rates of up to 494ng/h. The measured data show that a) FTOHs are present in indoor textiles (e.g. carpets), b) they are released at ambient temperatures and c) indoor air of shops selling outdoor textiles contains the highest levels of FTOH. Exposure of humans to perfluorooctanoic acid (PFOA) through absorption of FTOH and subsequent degradation is discussed on the basis of indoor air levels. Calculation of indoor air-related exposure using the median of the measured air levels revealed that exposure is on the same order of magnitude as the recently reported dietary intakes for a background-exposed population. On the basis of the 95th percentile, indoor air exposure to PFOA was estimated to exceed dietary exposure. However, indoor air-related intakes of FTOH are far below the tolerable daily intake (TDI) of PFOA, indicating that there is no risk to health, even when assuming an unrealistic complete degradation of FTOH into PFOA.

Professional ski waxers' exposure to PFAS and aerosol concentrations in gas phase and different particle size fractions

Previous reports show that professional ski waxers have elevated blood levels of perfluorinated substances (PFAS) such as perfluorooctanoate (PFOA) and are exposed to very high concentrations of PFAS in air during ski waxing. Aerosol exposure increases the risk of cardiovascular disease, and PFOA is a potential hormonal disruptor and carcinogen, and can affect the fatty acid metabolism. Animal studies have shown that 8:2 FTOH can undergo biotransformation to PFOA. For the first time, this study presents an occupational scenario of professional ski waxers who are exposed to extremely high dust levels as well as per- and polyfluorinated compounds. Personal and fixed measurements of total aerosol, inhalable and respirable fractions were performed during World Cup events 2007-2010. The occupational exposure limit (OEL) is exceeded in 37% of the personal measurements with concentrations up to 15 mg m(-3) in air. There are differences between personal and area total aerosol concentrations with levels from personal measurements twice as high as those from the area measurements. The personal levels for FTOH ranged up to 996 μg m(-3) (mean = 114 μg m(-3)) and for PFOA up to 4.89 μg m(-3) (mean = 0.53 μg m(-3)) in ENV+ sorbent samples as compared to the general exposure levels from air reaching only low ng m(-3) (<30 ng m(-3)) levels. FTOHs were not detected in aerosols but PFOA showed an average level of 12 μg m(-3) (range = 1.2-47 μg m(-3)). The ski waxers' exposure to paraffin fumes and PFAS is not in compliance with the occupational exposure standards and by far exceed the general populations' exposure. Preventive measures must be taken to minimize the exposure in this occupational group.

Human exposure to fluorotelomer alcohols, perfluorooctane sulfonate and perfluorooctanoate via house dust in Bavaria, Germany

This study aimed at investigating the presence and distribution of fluorotelomer alcohols (FTOHs), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in house dust to evaluate human exposure to these compounds via dust ingestion. 31 house dust samples were collected from Bavaria, Germany and analyzed for 4:2, 6:2, 8:2 and 10:2 FTOH, PFOS and PFOA. PFOA was the dominant compound in 79% of the dust samples, followed by PFOS and 8:2 FTOH, while 4:2 FTOH was not detected in any samples. The total concentration of per- and polyfluorinated compounds (PFCs) varied from 32.2 to 2456 ng/g. In addition, the total ingestion rate for PFCs was 0.4-135 ng/d for adults and 5.1-246 ng/d for toddlers, and the highest 8:2 FTOH-based PFOA intake via indoor dust was 0.24 ng/d for adults and 0.44 ng/d for toddlers. Overall, the results of this study demonstrate that dust ingestion is a minor pathway for human exposure to these PFCs; the PFC ingestion via indoor dust is generally low, and only under a worst scenario high intakes have to be expected for toddlers.

Biotransformation of fluorotelomer compound to perfluorocarboxylates in humans

Levels of perfluorocarboxylates (PFCAs) in biological compartments have been known for some time but their transport routes and distribution patterns are not properly elucidated. The opinions diverge whether the exposure of the general population occurs indirect through precursors or direct via PFCAs. Previous results showed that ski wax technicians are exposed to levels up to 92 000 ng/m(3) of 8:2 fluorotelomer alcohol (FTOH) via air and have elevated blood levels of PFCAs. Blood samples were collected in 2007-2011 and analyzed for C(4)-C(18) PFCAs, 6:2, 8:2 and 10:2 unsaturated fluorotelomer acids (FTUCAs) and 3:3, 5:3 and 7:3 fluorotelomer acids (FTCAs) using UPLC-MS/MS. Perfluorooctanoic acid (PFOA) was detected in levels ranging from 1.90 to 628 ng/mL whole blood (wb). Metabolic intermediates 5:3 and 7:3 FTCA were detected in all samples at levels up to 6.1 and 3.9 ng/mL wb. 6:2, 8:2 and 10:2 FTUCAs showed maximum levels of 0.07, 0.64 and 0.11 ng/mL wb. Also, for the first time levels of PFHxDA and PFOcDA were detected in the human blood at mean concentrations up to 4.22 ng/mL wb and 4.25 ng/mL wb respectively. The aim of this study was to determine concentrations of PFCAs and FTOH metabolites in blood from ski wax technicians.

Dietary exposure to perfluoroalkyl acids for the Swedish population in 1999, 2005 and 2010

Dietary intake has been hypothesized to be the major pathway of human exposure to perfluoroalkyl acids (PFAAs). However, difficulties associated with the analysis of PFAAs at ultra trace levels in food samples have prevented the confirmation of this hypothesis. In this study, the dietary intake of PFAAs for the general Swedish population was estimated by applying a highly sensitive analytical method to a set of archived food market basket samples from 1999, 2005 and 2010. Dietary exposure to perfluorooctane sulfonic acid (PFOS) (860-1440 pg kg⁻¹ day⁻¹), perfluoroundecanoic acid (PFUnDA) (90-210 pg kg⁻¹ day⁻¹), perfluorodecanoic acid (PFDA) (50-110 pg kg⁻¹ day⁻¹) and perfluorononanoic acid (PFNA) (70-80 pg kg⁻¹ day⁻¹) was dominated by the consumption of fish and meat. In contrast, dietary exposure to PFOA (350-690 pg kg⁻¹ day⁻¹) originated from low levels (8-62 pg g⁻¹) found in several high consumption food categories including cereals, dairy products, vegetables and fruit. The dietary intakes of PFOS and PFOA estimated in this study were 4 to 10 times lower compared to previous exposure modeling studies. Nevertheless, the dietary intake of PFOS and PFOA was still a factor of 6 to 10 higher than exposure through ingestion of household dust and drinking water estimated for the general Swedish population. For perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA) and perfluorohexane sulfonic acid (PFHxS) drinking water intake was the major exposure pathway (36-53% of the total exposure) whereas dust ingestion made a significant contribution (27-49%) to the total exposure for PFHxA, PFHpA, PFNA, perfluorotridecanoic acid (PFTrDA) and perfluorotetradecanoic acid (PFTeDA). Dietary intakes varied by less than a factor of three for all PFAAs during the different sampling years which demonstrates that dietary intake has been fairly constant over the past decade when many manufacturing changes occurred.

Atmospheric fate of poly- and perfluorinated alkyl substances (PFASs): II. Emission source strength in summer in Zurich, Switzerland

Fluorotelomer alcohols (FTOHs) and perfluorooctane sulfonamides (FOSAs) are present in consumer products and are semi-volatile precursors of persistent perfluoroalkyl acids (PFAAs). The high variability of levels of FTOHs and FOSAs in products makes it difficult to derive FTOH- and FOSA-emissions from urban areas based on emission factors. Here we used a multimedia mass balance model that describes the day-night cycle of semi-volatile organic chemicals in air to interpret measurements of 8:2 FTOH, 10:2 FTOH, MeFOSA and EtFOSA from a sampling campaign in summer 2010 in Zurich, Switzerland. The estimated emission source strength of the four substances follows the sequence: 8:2 FTOH (2.6 g/h) > 10:2 FTOH (0.75 g/h) > MeFOSA (0.08 g/h) > EtFOSA (0.05 g/h). There is no FTOHs- or FOSAs-related industry in Zurich. Accordingly, our estimates are representative of diffusive emissions during use and disposal of consumer products, and describe noticeable sources of these PFASs to the environment.

In vitro and in vivo studies of the toxic effects of perfluorononanoic acid on rat hepatocytes and Kupffer cells

This study investigated the toxic effects of perfluorononanoic acid (PFNA), a persistent organic pollutant, on rat hepatocytes and Kupffer cells in vitro and in vivo. The results showed that administration of 5μM PFNA increased the viabilities of the hepatocytes and the Kupffer cells. An exposure of 50μM PFNA did not alter the viabilities of both cells, as well as the release of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) from the primary cultured hepatocytes or the hepatocytes co-cultured with Kupffer cells. An exposure of 100μM PFNA only decreased the viability of the hepatocytes. The administration of PFNA changed the hepatocyte expression of several genes related to lipid metabolism in vitro and in vivo. Oil Red O Staining revealed that 5mg PFNA/kg/D treatment lead to dramatic accumulation of lipids in rat liver. At the same dose PFNA damaged hepatocytes histopathologically. Up-regulated expressions of the inflammatory cytokines occurred in the Kupffer cells treated with 50μM PFNA and in the livers of the rat receiving a 5mg PFNA/kg/D treatment. In addition, these cytokines also increased in serum of the rat receiving higher dose of PFNA. In summary, on the one hand, PFNA exposure affected the viability of the hepatocytes, hepatic lipid metabolism and lead to lipid accumulation in liver. On the other hand, for the first time, PFNA exposure was demonstrated to affect the viability of the Kupffer cells as well as their expression of cytokines, which involved in regulation of various liver functions. Therefore, we conclude that both the hepatocyte and the Kupffer cell contribute to the observed hepatotoxicity of PFNA.

Per- and polyfluorinated compounds (PFCs) in house dust and indoor air in Catalonia, Spain: implications for human exposure

A total of 27 per- and polyfluorinated compounds (PFCs) were determined in both house dust (n=10) and indoor air (n=10) from selected homes in Catalonia, Spain. Concentrations were found to be similar or lower than those previously reported for household microenvironments in other countries. Ten PFCs were detected in all house dust samples. The highest mean concentrations corresponded to perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA), 10.7 ng/g (median: 1.5 ng/g) and 10.4 ng/g (median: 5.4 ng/g), respectively, while the 8:2 fluorotelomer alcohol (FTOH) was the dominating neutral PFC at a concentration of 0.41 ng/g (median: 0.35 ng/g). The indoor air was dominated by the FTOHs, especially the 8:2 FTOH at a mean (median) concentration of 51 pg/m(3) (median: 42 pg/m(3)). A limited number of ionic PFCs were also detected in the indoor air samples. Daily intakes of PFCs were estimated for average and worst case scenarios of human exposure from indoor sources. For toddlers, this resulted in average intakes of ∑ionic PFCs of 4.9ng/day (0.33 ng/kg(bw)/day for a 15 kg toddlers) and ∑neutral PFCs of 0.072 ng/day (0.005 ng/kg(bw)/day) from house dust. For adults, the average daily intakes of dust were 3.6 and 0.053 ng/day (0.05 and 0.001 ng/kg(bw)/day for a 70 kg adult) for ∑ionic and ∑neutral PFCs, respectively. The average daily inhalation of ∑neutral PFCs was estimated to be 0.9 and 1.3 ng/day (0.06 and 0.02 ng/kg(bw)/day) for toddlers and adults, respectively. For PFOS, the main ionic PFC detected in indoor air samples, the median intakes (based on those samples where PFOS was detected), resulted in indoor exposures of 0.06 and 0.11 ng/day (0.004 and 0.002 ng/kg(bw)/day) for toddlers and adults, respectively. Based on previous studies on dietary intake and drinking water consumption, both house dust and indoor air contribute significantly less to PFC exposure within this population.

8:2 fluorotelomer alcohol: a one-day nose-only inhalation toxicokinetic study in the Sprague-Dawley rat with application to risk assessment

8:2 fluorotelomer alcohol (8:2 FTOH) inhalation exposure was investigated to (1) compare plasma metabolites to oral data, (2) conduct a route-to-route extrapolation (oral to inhalation), (3) develop a human equivalent air concentration (HEC) from a 90-day oral sub-chronic study in rats using BMD analysis, and (4) calculate a margin of exposure (MOE) between the HEC and measured air concentrations. Male and female rats were exposed nose-only for 6h at 3 or 30mg/m(3). Blood was collected at 1, 3 and 6h during exposure and 6 and 18h post exposure. Alcohol, perfluorocarboxylic acid and polyfluorinated acid metabolites were determined in plasma by LC-MS/MS. 8:2 FTOH was <LOQ (32nM) at the low exposure and quantifiable (37-69nM) at the high exposure. The quantifiable metabolites in plasma were dose proportional and comprised mainly of 8:2 FTCA, 7:3 Acid, and PFOA. By kinetic modeling, the yields of the terminal products 7:3 Acid (1.6-2.1 and 0.9mol%) and PFOA (1.0-1.2 and 0.3mol%) of the inhaled dose were low for male and female rats, respectively. The kinetic yield of PFOA after oral dosing was similar (1.1-1.7-fold) for male rats and greater (8-9-fold) for female rats relative to inhalation exposure, an observation confirmed by non-compartmental analysis. A BMDL10% (3.7mg/kg/day) was derived for mild hepatic necrosis observed in male rats following a 90-day oral dose study with 8:2 FTOH. The corresponding HECs were 1.8 and 3.7mg/m(3), which gave MOE values ranging from 1.8×10(4) to 6.1×10(6) based on reported ambient air concentrations of 0.3-209ng/m(3). These findings demonstrate rapid 8:2 FTOH uptake and clearance by the inhalation route and a consistent metabolite profile between inhalation and oral exposures in rats. No toxicity is expected in humans from typical ambient 8:2 FTOH air exposures.

Is indirect exposure a significant contributor to the burden of perfluorinated acids observed in humans?

In comparison to other persistent organic pollutants, human fluorochemical contamination is relatively complicated. This complication arises at least in part from a disparity between the chemicals used commercially and those measured in the environment and humans. Commercial fluorochemical products are dominated by fluorinated polymers used in textile or carpet applications, or fluorosurfactants used in applications ranging from personal care products, leveling and wetting agents, to greaseproofing food-contact materials. Investigations into environmental and human fluorochemical contamination have focused on perfluorinated acids (PFAs), either the perfluorinated carboxylates (PFCAs) or sulfonates (PFSAs). In this review we will present an overview of data related to human fluorochemical exposure including a discussion of fluorochemical production, concentrations in exposure media, biotransformation processes producing PFAs, and trends in human sera. These data will be presented in the context of how they can inform sources of human PFA contamination, specifically whether the contamination results from direct PFA exposure or indirect exposure via the biotransformation of commercial fluorochemicals or their residuals. Concentrations of both perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) began to decrease in human sera around the year 2000, a change that mirrored the 2000-2002 phase-out of perfluorooctane sulfonyl fluoride (POSF) production. These temporal trends suggest exposure to current-use POSF-based materials was a significant source of PFOA and PFOS exposure prior to 2000. Relatively slow PFOA elimination and increasing concentrations of the C9 and C10 PFCAs in human sera suggest continued PFCA exposure, without similar exposure to PFOS, which is consistent with indirect exposure via the biotransformation of fluorotelomer-based materials. Conversely, human exposure models have suggested direct exposure to PFAs present in food items is the major source of human contamination. The data set presented here cannot unequivocally delineate between direct and indirect human exposure, however temporal trends in human sera and exposure media are consistent with indirect exposure representing a significant portion of observed human PFA contamination.

Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins

The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers.

Exercise-Induced Lung Disease: Too Much of a Good Thing?

Exercise in children has important health benefits. However, in elite endurance athletes, there is an increased prevalence of exercise-induced bronchoconstriction and airway inflammation. Particularly at risk are those who practice in cold weather, ice rinks, swimming pools, and air pollution. The inflammation is caused by repetitive episodes of hyperventilation of cold, dry air, allergens, or toxins such as chlorine or air pollution. Children may be particularly at risk for lung injury under these conditions because of the immaturity and ongoing development of their lung. However, studies in pediatric athletes and exercising young children are sparse. Epithelial injury associated with hyperventilation of cold, dry air has not been described in children. However, exercise in the presence of air pollution and chlorine is associated with airway injury and the development of asthma in children; the effect appears to be modulated by both atopy and genetic polymorphisms. While management of exercise-induced bronchoconstriction and asthma is well established, there is little data to guide treatment or prevention of remodeling in athletes or inhalational lung injury in children. Studies underscore the need to maintain high levels of air quality. More investigations should be undertaken to better define the natural history, pathophysiology, and treatment of exercise-induced pulmonary inflammation in both elite athletes and exercising children.