A propensity score matched analysis of liver transplantation outcomes in the setting of preservation solution shortage.

The recent shortage of the University of Wisconsin (UW) solution prompted increased utilization of histidine-tryptophan-ketoglutarate (HTK) solution for liver graft preservation. This contemporary study analyzed deceased donor liver transplant outcomes following preservation with HTK vs UW. Patients receiving deceased donor liver transplantations between January 1, 2019, and June 30, 2022, were retrospectively identified utilizing the Organ Procurement and Transplant Network database, stratified by preservation with HTK vs UW, and a propensity score matching analysis was performed. Outcomes assessed included rates of primary nonfunction, graft survival, and patient survival. There were 4447 patients in each cohort. Primary nonfunction occurred in 60 (1.35%) patients in the HTK group vs 25 (0.54%) in the UW group (P < .001). HTK was associated with lower 90-day graft survival (94.39% vs 96.09%; P < .001) and 90-day patient survival (95.97% vs 97.38%; P = .001). Unmatched donation after cardiac death-specific analysis of HTK vs UW demonstrated respective rates of primary nonfunction of 1.63% vs 0.82% (P = .20), 90-day graft survival of 92.50% vs 95.29% (P = .069), and 90-day patient survival of 93.90% vs 96.35% (P = .077). These results suggest that HTK may not be an equivalent preservation solution for deceased donor liver transplantation.

Extracorporeal membrane oxygenation for cardiopulmonary failure in organ donation: Assessing liver transplant outcomes.

Liver transplantation continues to face significant organ shortages and efficient utilization of marginal donors is paramount. This study evaluates the practice patterns and outcomes in liver transplantation when utilizing allografts from marginal donors who required extracorporeal membrane oxygenation (ECMO) support. We performed a retrospective review of the Gift of Life (PA, NJ, DE) organ-procuring organization database for transplants performed using donors supported on ECMO for nondonation purposes. These were cross-referenced to the transplant recipients within the Organ Procurement and Transplantation Network database, and the outcomes of liver transplants using donors on ECMO support were compared with those not requiring ECMO. Organ use and nonuse patterns were then evaluated in ECMO-supported donors, identifying the factors associated with nonuse compared with the factors associated with graft failure. Thirty-nine of the 84 ECMO-supported donors contributing at least one intra-abdominal organ for transplant donated a liver. Graft survival and patient survival up to 5 years were comparable between transplants from ECMO and non-ECMO-supported donors, and no cases of primary nonfunction were seen in the ECMO group. ECMO support was not associated with 1-year graft failure on regression modeling. Additional regression analyses within the ECMO donor population identified bacteremia (HR: 19.81) and elevated total bilirubin at donation (HR: 2.44) as predictive of post-transplant graft failure. Livers from donors supported on ECMO before donation appear safe to use in select transplant settings. Better understanding of the impact of predonation ECMO on liver allograft function will help guide the optimal use of these scarcely used donors.

Cookstove Emissions and Performance Evaluation Using a New ISO Protocol and Comparison of Results with Previous Test Protocols.

In 2018, the International Organization for Standardization (ISO) 19867-1 "Harmonized laboratory test protocols" were released for establishing improved quality and comparability for data on cookstove air pollutant emissions, efficiency, safety, and durability. This is the first study that compares emissions [carbon dioxide, carbon monoxide, total hydrocarbons, methane, nitrogen oxides, fine particulate matter (PM2.5), organic carbon, elemental carbon, and ultrafine particles] and efficiency data between the ISO protocol and the Water Boiling Test (WBT). The study examines six stove/fuel combinations [liquefied petroleum gas (LPG), pellet, wood fan, wood rocket, three stone fire, and charcoal] tested in the same US EPA laboratory. Evaluation of the ISO protocol shows improvements over previous test protocols and that results are relatively consistent with former WBT data in terms of tier ratings for emissions and efficiency, as defined by the ISO 19867-3 "Voluntary Performance Targets." Most stove types remain similarly ranked using ISO and WBT protocols, except charcoal and LPG are in higher PM2.5 tiers with the ISO protocol. Additionally, emissions data including polycyclic aromatic hydrocarbons are utilized to compare between the ISO and Firepower Sweep Test (FST) protocols. Compared to the FST, the ISO protocol results in generally higher PM2.5 tier ratings.

Relative contributions of selected multigeneration products to chamber SOA formed from photooxidation of a range (C10-C17) of n-alkanes under high NO x conditions.

A series of chamber experiments was conducted to investigate the composition of secondary organic aerosol (SOA) following oxidation of a range of parent n-alkanes (C10-C17) in the presence of NO x . The relative contribution of selected species representing first, second, and higher generation products to SOA mass was measured using a high-resolution aerosol mass spectrometer. Gas chromatography was also used for a limited set of amenable species. Relative contributions varied substantially across the range of investigated alkanes reflecting slight changes in SOA composition. The contribution of first-generation cyclic hemiacetal is minimal toward the small end of the investigated range and gradually increase with n-alkane size. The relative contribution of second generation and higher nitrate-containing species, in contrast, decrease with an increased alkane size. A similar trend is observed for relative contribution of organonitrates to SOA. Finally, SOA yield and composition are sensitive to water vapor concentrations. This sensitivity is limited to a narrow range (dry to ~15% RH) with little, if any, impact above 15% suggesting that this impact may be negligible under ambient conditions. The impact of water vapor also appears to decrease with increasing alkane carbon number.

Effects of Cold Temperature and Ethanol Content on VOC Emissions from Light-Duty Gasoline Vehicles.

Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle testing was conducted using a three-phase LA92 driving cycle in a temperature-controlled chassis dynamometer at two ambient temperatures (-7 and 24 °C). The cold start driving phase and cold ambient temperature increased VOC and MSAT emissions up to several orders of magnitude compared to emissions during other vehicle operation phases and warm ambient temperature testing, respectively. As a result, calculated ozone formation potentials (OFPs) were 7 to 21 times greater for the cold starts during cold temperature tests than comparable warm temperature tests. The use of E85 fuel generally led to substantial reductions in hydrocarbons and increases in oxygenates such as ethanol and acetaldehyde compared to E0 and E10 fuels. However, at the same ambient temperature, the VOC emissions from the E0 and E10 fuels and OFPs from all fuels were not significantly different. Cold temperature effects on cold start MSAT emissions varied by individual MSAT compound, but were consistent over a range of modern spark ignition vehicles.

Generation and characterization of diesel engine combustion emissions from petroleum diesel and soybean biodiesel fuels and application for inhalation exposure studies.

Biodiesel made from the transesterification of plant- and animal-derived oils is an important alternative fuel source for diesel engines. Although numerous studies have reported health effects associated with petroleum diesel emissions, information on biodiesel emissions are more limited. To this end, a program at the U.S. EPA assessed health effects of biodiesel emissions in rodent inhalation models. Commercially obtained soybean biodiesel (B100) and a 20% blend with petroleum diesel (B20) were compared to pure petroleum diesel (B0). Rats and mice were exposed independently for 4 h/day, 5 days/week for up to 6 weeks. Exposures were controlled by dilution air to obtain low (50 µg/m(3)), medium (150 µg/m(3)) and high (500 µg/m(3)) diesel particulate mass (PM) concentrations, and compared to filtered air. This article provides details on facilities, fuels, operating conditions, emission factors and physico-chemical characteristics of the emissions used for inhalation exposures and in vitro studies. Initial engine exhaust PM concentrations for the B100 fuel (19.7 ± 0.7 mg/m(3)) were 30% lower than those of the B0 fuel (28.0 ± 1.5 mg/m(3)). When emissions were diluted with air to control equivalent PM mass concentrations, B0 exposures had higher CO and slightly lower NO concentrations than B100. Organic/elemental carbon ratios and oxygenated methyl esters and organic acids were higher for the B100 than B0. Both the B0 and B100 fuels produced unimodal-accumulation mode particle-size distributions, with B0 producing lower concentrations of slightly larger particles. Subsequent papers in this series will describe the effects of these atmospheres on cardiopulmonary responses and in vitro genotoxicity studies.

Burn pit-related smoke causes developmental and behavioral toxicity in zebrafish: Influence of material type and emissions chemistry.

Combustion of mixed materials during open air burning of refuse or structural fires in the wildland urban interface produces emissions that worsen air quality, contaminate rivers and streams, and cause poor health outcomes including developmental effects. The zebrafish, a freshwater fish, is a useful model for quickly screening the toxicological and developmental effects of agents in such species and elicits biological responses that are often analogous and predictive of responses in mammals. The purpose of this study was to compare the developmental toxicity of smoke derived from the burning of 5 different burn pit-related material types (plywood, cardboard, plastic, a mixture of the three, and the mixture plus diesel fuel as an accelerant) in zebrafish larvae. Larvae were exposed to organic extracts of increasing concentrations of each smoke 6-to-8-hr post fertilization and assessed for morphological and behavioral toxicity at 5 days post fertilization. To examine chemical and biological determinants of toxicity, responses were related to emissions concentrations of polycyclic hydrocarbons (PAH). Emissions from plastic and the mixture containing plastic caused the most pronounced developmental effects, including mortality, impaired swim bladder inflation, pericardial edema, spinal curvature, tail kinks, and/or craniofacial deformities, although all extracts caused concentration-dependent effects. Plywood, by contrast, altered locomotor responsiveness to light changes to the greatest extent. Some morphological and behavioral responses correlated strongly with smoke extract levels of PAHs including 9-fluorenone. Overall, the findings suggest that material type and emissions chemistry impact the severity of zebrafish developmental toxicity responses to burn pit-related smoke.

Quantifying functional group compositions of household fuel-burning emissions.

Globally, billions of people burn fuels indoors for cooking and heating, which contributes to millions of chronic illnesses and premature deaths annually. Additionally, residential burning contributes significantly to black carbon emissions, which have the highest global warming impacts after carbon dioxide and methane. In this study, we use Fourier transform infrared spectroscopy (FTIR) to analyze fine-particulate emissions collected on Teflon membrane filters from 15 cookstove types and 5 fuel types. Emissions from three fuel types (charcoal, kerosene, and red oak wood) were found to have enough FTIR spectral response for functional group (FG) analysis. We present distinct spectral profiles for particulate emissions of these three fuel types. We highlight the influential FGs constituting organic carbon (OC) using a multivariate statistical method and show that OC estimates by collocated FTIR and thermal-optical transmittance (TOT) are highly correlated, with a coefficient determination of 82.5 %. As FTIR analysis is fast and non-destructive and provides complementary FG information, the analysis method demonstrated herein can substantially reduce the need for thermal-optical measurements for source emissions.

Extrahepatic Cholangiocarcinoma: Genomic Variables Associated With Anatomic Location and Outcome.

PURPOSE: This study aimed to define genomic differences between perihilar cholangiocarcinoma (PCA) and distal cholangiocarcinoma (DCA) and identify genomic determinants of survival. MATERIALS AND METHODS: Consecutive patients with ECA with tissue for targeted next-generation sequencing were analyzed, stratified by anatomic site (PCA/DCA), disease extent, and treatment. Associations between genomic alterations, clinicopathologic features, and outcomes were analyzed using Cox proportional hazards regression to compare survival. RESULTS: In total, 224 patients diagnosed between 2004 and 2022 (n = 127 PCA; n = 97 DCA) met inclusion criteria. The median survival was 29 months (43 after resection and 17 from diagnosis for unresectable disease). Compared with PCA, DCA was enriched in TP53alt (alterations; 69% v 33%; Q < 0.01), epigenetic pathway alterations (45% v 29%; Q = 0.041), and had more total altered pathways (median 3 v 2; Q < 0.01). KRASalt frequency was similar between PCA (36%) and DCA (37%); however, DCA was enriched in KRAS G12D (19% v 9%; P = .002). No other clinicopathologic or genomic variables distinguished subtypes. In resected patients, no genomic alterations were associated with outcome. However, in unresectable patients, CDKN2Aalt (hazard ratio [HR], 2.59 [1.48 to 4.52]) and APCalt (HR, 5.11 [1.96 to 13.3]) were associated with reduced survival. For the entire cohort, irresectability (HR, 3.13 [2.25 to 4.36]), CDKN2Aalt (HR, 1.80 [1.80 to 2.68]), and APCalt (HR, 2.00 [1.04 to 3.87]) were associated with poor survival. CONCLUSION: CDKN2Aalt and APCalt were associated with poor survival in ECA, primarily in advanced disease. As PCA and DCA were genetically similar, coanalysis of PCA and DCA in future genomic studies is reasonable.

Concordance in Oncogenic Alterations Between the Primary Tumor and Advanced Disease: Insights Into the Heterogeneity of Intrahepatic Cholangiocarcinoma.

PURPOSE: Intrahepatic cholangiocarcinoma (ICCA) is characterized by significant phenotypic and clinical heterogeneities and poor response to systemic therapy, potentially related to underlying heterogeneity in oncogenic alterations. We aimed to characterize the genomic heterogeneity between primary tumors and advanced disease in patients with ICCA. METHODS: Biopsy-proven CCA specimens (primary tumor and paired advanced disease [metastatic disease, progressive disease on systemic therapy, or postoperative recurrence]) from two institutions were subjected to targeted next-generation sequencing. Overall concordance (oncogenic driver mutations, copy number alterations, and fusion events) and mutational concordance (only oncogenic mutations) were compared across paired samples. A subgroup analysis was performed on the basis of exposure to systemic therapy. Patients with extrahepatic CCA (ECCA) were included as a comparison group. RESULTS: Sample pairs from 65 patients with ICCA (n = 54) and ECCA (n = 11) were analyzed. The median time between sample collection was 19.6 months (range, 2.7-122.9). For the entire cohort, the overall oncogenic concordance was 49% and the mutational concordance was 62% between primary and advanced disease samples. Subgroup analyses of ICCA and ECCA revealed overall/mutational concordance rates of 47%/58% and 60%/84%, respectively. Oncogenic concordance was similarly low for pairs exposed to systemic therapy between sample collections (n = 50, 53% overall, 68% mutational). In patients treated with targeted therapy for IDH1/2 alterations (n = 6) or FGFR2 fusions (n = 3), there was 100% concordance between the primary and advanced disease specimens. In two patients, FGFR2 (n = 1) and IDH1 (n = 1) alterations were detected de novo in the advanced disease specimens. CONCLUSION: The results reflect a high degree of heterogeneity in ICCA and argue for reassessment of the dominant driver mutations with change in disease status.

Hemorrhage Sites and Mitigation Strategies After Pancreaticoduodenectomy.

Importance: Postpancreatectomy hemorrhage is an uncommon but highly morbid complication of pancreaticoduodenectomy. Clinical evidence often draws suspicion to the gastroduodenal artery stump, even without a clear source. Objective: To determine the frequency of gastroduodenal artery bleeding compared to other sites and the results of mitigation strategies. Design, Setting, and Participants: This cohort study involved a retrospective analysis of data for consecutive patients who had pancreaticoduodenectomy from 2011 to 2021 at Memorial Sloan Kettering Cancer Center (MSK) and Thomas Jefferson University Hospital (TJUH). Exposures: Demographic, perioperative, and disease-related variables. Main Outcomes and Measures: The incidence, location, treatment, and outcomes of primary (initial) and secondary (recurrent) hemorrhage requiring invasive intervention were analyzed. Imaging studies were re-reviewed by interventional radiologists to confirm sites. Results: Inclusion criteria were met by 3040 patients (n = 1761 MSK, n = 1279 TJUH). Patients from both institutions were similar in age (median [IQR] age at MSK, 67 [59-74] years, and at TJUH, 68 [60-75] years) and sex (at MSK, 814 female [46.5%] and 947 male [53.8%], and at TJUH, 623 [48.7%] and 623 male [51.3%]). Primary hemorrhage occurred in 90 patients (3.0%), of which the gastroduodenal artery was the source in 15 (16.7%), unidentified sites in 24 (26.7%), and non-gastroduodenal artery sites in 51 (56.7%). Secondary hemorrhage occurred in 23 patients; in 4 (17.4%), the gastroduodenal artery was the source. Of all hemorrhage events (n = 117), the gastroduodenal artery was the source in 19 (16.2%, 0.63% incidence in all pancreaticoduodenectomies). Gastroduodenal artery hemorrhage was more often associated with soft gland texture (14 [93.3%] vs 41 [62.1%]; P = .02) and later presentation (median [IQR], 21 [15-26] vs 10 days [5-18]; P = .002). Twenty-three patients underwent empirical gastroduodenal artery embolization or stent placement, 7 (30.4%) of whom subsequently experienced secondary hemorrhage. Twenty percent of all gastroduodenal artery embolizations/stents (8/40 patients), including 13% (3/13 patients) of empirical treatments, were associated with significant morbidity (7 hepatic infarction, 4 biliary stricture), with a 90-day mortality rate of 38.5% (n = 5) for patients with these complications vs 7.8% without (n = 6; P = .008). Ninety-day mortality was 12.2% (n = 11) for patients with hemorrhage (3 patients [20%] with primary gastroduodenal vs 8 [10.7%] for all others; P = .38) compared with 2% (n = 59) for patients without hemorrhage. Conclusions and Relevance: In this study, postpancreatectomy hemorrhage was uncommon and the spectrum was broad, with the gastroduodenal artery responsible for a minority of bleeding events. Empirical gastroduodenal artery embolization/stent without obvious sequelae of recent hemorrhage was associated with significant morbidity and rebleeding and should not be routine practice. Successful treatment of postpancreatectomy hemorrhage requires careful assessment of all potential sources, even after gastroduodenal artery mitigation.

Carbonaceous aerosols emitted from light-duty vehicles operating on gasoline and ethanol fuel blends.

This study examines the chemical properties of carbonaceous aerosols emitted from three light-duty gasoline vehicles (LDVs) operating on gasoline (e0) and ethanol-gasoline fuel blends (e10 and e85). Vehicle road load simulations were performed on a chassis dynamometer using the three-phase LA-92 unified driving cycle (UDC). Effects of LDV operating conditions and ambient temperature (-7 and 24 °C) on particle-phase semivolatile organic compounds (SVOCs) and organic and elemental carbon (OC and EC) emissions were investigated. SVOC concentrations and OC and EC fractions were determined with thermal extraction-gas chromatography-mass spectrometry (TE-GC-MS) and thermal-optical analysis (TOA), respectively. LDV aerosol emissions were predominantly carbonaceous, and EC/PM (w/w) decreased linearly with increasing fuel ethanol content. TE-GC-MS analysis accounted for up to 4% of the fine particle (PM2.5) mass, showing the UDC phase-integrated sum of identified SVOC emissions ranging from 0.703 µg km(-1) to 18.8 µg km(-1). Generally, higher SVOC emissions were associated with low temperature (-7 °C) and engine ignition; mixed regression models suggest these emissions rate differences are significant. Use of e85 significantly reduced the emissions of lower molecular weight PAH. However, a reduction in higher molecular weight PAH entities in PM was not observed. Individual SVOC emissions from the Tier 2 LDVs and fuel technologies tested are substantially lower and distributed differently than those values populating the United States emissions inventories currently. Hence, this study is likely to influence future apportionment, climate, and air quality model predictions that rely on source combustion measurements of SVOCs in PM.

Idiopathic left-sided ovarian vein thrombosis in a post-menopausal woman.

Ovarian vein thrombosis (OVT) is a rare thromboembolic condition largely involving the right ovarian vein. Risk factors include pregnancy/ peripartum period, oestrogen therapy, recent surgery or hospitalisation, malignancy, pelvic inflammatory diseases, and thrombophilia; OVT without risk factors is considered idiopathic. We present a rare case of idiopathic left-sided OVT in a post-menopausal woman in her 60s with insignificant past medical history and no identifiable risk factors. She presented with isolated left -lower -quadrant abdominal pain ultimately found to have OVT on computed tomography (CT) scan and confirmed with magnetic resonance imaging (MRI). The patient was initially treated with low-molecular-weight heparin and then transitioned to apixaban. She remained symptom-free at 3-month follow-up. Five previous cases of idiopathic left-sided OVT have been reported to-date, but this is the first case in a postmenopausal woman that has not been associated with hypercoagulable risk factors nor further thromboembolic complications.

Development of Volatility Distributions for Organic Matter in Biomass Burning Emissions.

The volatility distribution of organic emissions from biomass burning and other combustion sources can determine their atmospheric evolution due to partitioning/aging. The gap between measurements and models predicting secondary organic aerosol has been partially attributed to the absence of semi- and intermediate volatility organic compounds (S/I-VOC) in models and measurements. However, S/I-VOCs emitted from these sources and typically quantified using the volatility basis framework (VBS) are not well understood. For example, the amount and composition of S/I-VOCs and their variability across different biomass burning sources such as residential woodstoves, open field burns, and laboratory simulated open burning are uncertain. To address this, a novel filter-in-tube sorbent tube sampling method collected S/I-VOC samples from biomass burning experiments for a range of fuels and combustion conditions. Filter-in-tube samples were analyzed using thermal desorption-gas chromatography-mass spectrometry (TD/GC/MS) for compounds across a wide range of volatilities (saturation concentrations; -2 ≤ logC* ≤ 6). The S/I-VOC measurements were used to calculate volatility distributions for each emissions source. The distributions were broadly consistent across the sources with IVOCs accounting for 75% - 90% of the total captured organic matter, while SVOCs and LVOCs were responsible for 6% - 13% and 1% - 12%, respectively. The distributions and predicted partitioning were generally consistent with literature. Particulate matter emission factors spanned two orders of magnitude across the sources. This work highlights the potential of inferring gas-particle partitioning behavior of biomass burning emissions using filter-in-tube sorbent samples analyzed offline. This simplifies both sampling and analysis of S/I-VOCs for studies focused on capturing the full range of organics emitted.

Assessing Kidney Transplantation Using ECMO-Supported Donors Within a KDPI-Based Allocation System.

Background: Organ donors supported by extracorporeal membrane oxygenation (ECMO) have historically been considered high-risk and are judiciously utilized. This study examines transplant outcomes using renal allografts from donors supported on ECMO for nondonation purposes. Methods: Retrospective review of the Gift of Life (Pennsylvania, New Jersey, Delaware) organ procurement organization database, cross-referenced to the Organ Procurement and Transplantation Network database, assessed kidney transplants using donors supported on venoarterial (VA) and venovenous (VV) ECMO for nondonation purposes. Transplants using VA- and VV-ECMO donors were compared with Kidney Donor Profile Index (KDPI)-stratified non-ECMO donors. Regression modeling of the entire ECMO and non-ECMO populations assessed ECMO as predictive of graft survival. Additional regression of the ECMO population alone assessed for donor features associated with graft survival. Results: Seventy-eight ECMO donors yielded 128 kidney transplants (VA: 80, VV: 48). Comparing outcomes using these donors to kidney transplants using organs from KDPI-stratified non-ECMO donors, VA- and VV-ECMO donor grafts conferred similar rates of delayed graft function and posttransplant renal function to KDPI-matched non-ECMO counterparts. VA-ECMO kidneys demonstrated superior graft survival compared with the lowest-quality (KDPI 86%-100%) non-ECMO kidneys and similar graft survival to KDPI <85% non-ECMO kidneys. VV-ECMO showed inferior graft survival to all but the lowest-quality (KDPI 86%-100%) non-ECMO kidneys. VV-ECMO, but not VA-ECMO, was associated with increased risk of graft loss on multivariable regression (hazard ratios-VA: 1.02, VV: 2.18). Higher KDPI, advanced age, increased body mass index, hypertension, and diabetes were identified as high-risk features of ECMO donors. Conclusions: Kidney transplantation using appropriately selected ECMO donors can safely expand the donor pool. Ongoing studies are necessary to determine best practice patterns using kidneys from these donors.

Characterization of PFAS air emissions from thermal application of fluoropolymer dispersions on fabrics.

During thermal processes utilized in affixing fluoropolymer coatings dispersion to fibers and fabrics, coating components are vaporized. It is suspected that per- and polyfluoroalkyl substances (PFAS) from the dispersions may undergo chemical transformations at the temperatures used, leading to additional emitted PFAS thermal byproducts. It is important to characterize these emissions to support evaluation of the resulting environmental and health impacts. In this study, a bench-scale system was built to simulate this industrial process via thermal application of dispersions to fiberglass utilizing relevant temperatures and residence times in sequential drying, baking, and sintering steps. Experiments were performed with two commercially available dispersions and a simple model mixture containing a single PFAS (6:2 fluorotelomer alcohol [6:2 FTOH]). Vapor-phase emissions were sampled and characterized by several off-line and real-time mass spectrometry techniques for targeted and nontargeted PFAS. Results indicate that multiple PFAS thermal transformation products and multiple nonhalogenated organic species were emitted from the exit of the high temperature third (sintering) furnace when 6:2 FTOH was the only PFAS present in the aqueous mixture. This finding supports the hypothesis that temperatures typical of these industrial furnaces may also induce chemical transformations within the fluorinated air emissions. Experiments using the two commercial fluoropolymer dispersions indicate air emissions of part-per-million by volume (ppmv) concentrations of heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether (Fluoroether E1), as well as other PFAS at operationally relevant temperatures. We suspect that E1 is a direct thermal decomposition product (via decarboxylation) of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid (commonly referred to as HFPO-DA) present in the dispersions. Other thermal decomposition products, including the monomer, tetrafluoroethene, may originate from the PFAS used to stabilize the dispersion or from the polymer particles in suspension. This study represents the first researcher-built coating application simulator to report nontargeted PFAS emission characterization, real-time analyses, and the quantification of 30 volatile target PFAS.Implications: Thermal processes used to affix fluoropolymers to fabrics are believed to be a source of PFAS air emissions. These coating operations are used by many large and small manufacturers and typically do not currently require any air emissions control. This research designed and constructed a bench-scale system that simulates these processes and used several off-line and advanced real-time mass spectroscopy techniques to characterize PFAS air emissions from two commercial fluoropolymer dispersions. Further, as the compositions of commercial dispersions are largely unknown, a model three-component solution containing a single PFAS was used to characterize emissions of multiple PFAS thermal transformation products at operationally relevant conditions. This research shows that fluoropolymer fabric coating facilities can be sources of complex mixtures of PFAS air emissions that include volatile and semivolatile PFAS present in the dispersions, as well as PFAS byproducts formed by the thermal transformation of fluorocarbon and hydrocarbon species present in these dispersions.

Pilot-Scale Thermal Destruction of Per- and Polyfluoroalkyl Substances in a Legacy Aqueous Film Forming Foam.

The destruction of per- and polyfluoroalkyl substances (PFAS) is critical to ensure effective remediation of PFAS contaminated matrices. The destruction of hazardous chemicals within incinerators and other thermal treatment processes has historically been determined by calculating the destruction efficiency (DE) or the destruction and removal efficiency (DRE). While high DEs, >99.99%, are deemed acceptable for most hazardous compounds, many PFAS can be converted to other PFAS at low temperatures resulting in high DEs without full mineralization and the potential release of the remaining fluorocarbon portions to the environment. Many of these products of incomplete combustion (PICs) are greenhouse gases, most have unknown toxicity, and some can react to create new perfluorocarboxylic acids. Experiments using aqueous film forming foam (AFFF) and a pilot-scale research combustor varied the combustion environment to determine if DEs indicate PFAS mineralization. Several operating conditions above 1090 °C resulted in high DEs and few detectable fluorinated PIC emissions. However, several conditions below 1000 °C produced DEs >99.99% for the quantifiable PFAS and mg/m3 emission concentrations of several non-polar PFAS PICs. These results suggest that DE alone may not be the best indication of total PFAS destruction, and additional PIC characterization may be warranted.

Pyrolysis processing of PFAS-impacted biosolids, a pilot study.

Concentrations of per- and poly-fluoroalkyl substances (PFAS) present in wastewater treatment biosolids are a growing concern. Pyrolysis is a thermal treatment technology for biosolids that can produce a useful biochar product with reduced levels of PFAS and other contaminants. In August 2020, a limited-scope study investigated target PFAS removal of a commercial pyrolysis system processing biosolid with the analysis of 41 target PFAS compounds in biosolids and biochar performed by two independent laboratories. The concentrations of 21 detected target compounds in the input biosolids ranged between approximately 2 µg/kg and 85 µg/kg. No PFAS compounds were detected in the biochar. The PFAS concentrations in the biochar were assumed to equal the compounds' minimum detection limits (MDLs). The pyrolysis system's target PFAS removal efficiencies (REs) were estimated to range between >81.3% and >99.9% (mean >97.4%) with the lowest REs being associated with the lowest detected PFAS concentrations and the highest MDLs. No information on non-target PFAS compounds in influent or effluent media or products of incomplete combustion was considered. Selected gaseous emissions were measured by Fourier transform infrared spectroscopy and gas chromatography time-of-flight mass spectrometry to provide additional information on air emissions after process controls. This limited-scope study indicated that additional research to further understand this process is warranted.Implications: Development of alternative approaches to manage PFAS-impacted biosolids is of emerging international importance. A commercially operating biosolid pyrolysis process was shown to lower target PFAS levels in produced biochar. Additional research is warranted to understand all potential PFAS transformation emission routes and optimal air pollution emissions control strategies for this technology class.