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Per- and polyfluoroalkyl substances (PFAS) are a widespread and persistent class of contaminants posing significant environmental and human health concerns. Comprehensive understanding of the modes of action underlying toxicity among structurally diverse PFAS is mostly lacking. To address this need, we recently reported on our application of developing zebrafish to evaluate a large library of PFAS for developmental toxicity. In the present study, we prioritized 15 bioactive PFAS that induced significant morphological effects and performed RNA-sequencing to characterize early transcriptional responses at a single timepoint (48 h post fertilization) after early developmental exposures (8 h post fertilization). Internal concentrations of 5 of the 15 PFAS were measured from pooled whole fish samples across multiple timepoints between 24–120 h post fertilization, and additional temporal transcriptomics at several timepoints (48–96 h post fertilization) were conducted for Nafion byproduct 2. A broad range of differentially expressed gene counts were identified across the PFAS exposures. Most PFAS that elicited robust transcriptomic changes affected biological processes of the brain and nervous system development. While PFAS disrupted unique processes, we also found that similarities in some functional head groups of PFAS were associated with the disruption in expression of similar gene sets. Body burdens after early developmental exposures to select sulfonic acid PFAS, including Nafion byproduct 2, increased from the 24–96 h post fertilization sampling timepoints and were greater than those of sulfonamide PFAS of similar chain lengths. In parallel, the Nafion byproduct 2-induced transcriptional responses increased between 48 and 96 h post fertilization. PFAS characteristics based on toxicity, transcriptomic effects, and modes of action will contribute to further prioritization of PFAS structures for testing and informed hazard assessment.

Summary: Per- and polyfluoroalkyl substances (PFAS) are ubiquitously detected in environmental and biological samples and cause adverse health effects. Studies have predominately focused on long-chain PFAS, with far fewer addressing short-chain alternatives. This study leveraged embryonic zebrafish to investigate developmental toxicity of a short-chain series: perfluorobutane sulfonate (PFBS), perfluoropentanoic acid (PFPeA), perfluorobutane sulfonamide (FBSA), and 4:2 fluorotelomer sulfonic acid (4:2 FTS). Following static exposures at 8 h postfertilization (hpf) to each chemical (1–100 μM), morphological and behavioral endpoints were assessed at 24 and 120 hpf. Only FBSA induced abnormal morphology, while exposure to all chemicals caused aberrant larval behavior. RNA sequencing at 48 hpf following 47 μM exposures revealed only FBSA significantly disrupted normal gene expression. Measured tissue concentrations were FBSA > PFBS > 4:2 FTS > PFPeA. This study demonstrates functional head groups impact bioactivity and bioconcentration.

Ubiquitous anthropogenic contaminants of concern, per- and polyfluoroalkyl substances (PFAS) are frequently detected in the environment and human populations around the world. Diet is a predominate route of human exposure, and PFAS are frequently measured in food. Manufacturing trends have shifted from legacy PFAS to shorter-chain alternatives that are suggested to be safer, such as perfluorohexanoic acid (PFHxA). However, the current amount of data to support safety assessments of these alternatives is not yet sufficient. The present study investigated the effects of a 42-day dietary exposure to 1, 10, or 100 ng/g PFHxA in juvenile zebrafish. The zebrafish model was leveraged to interrogate morphometrics, fecundity, and numerous behavior endpoints across multiple generations. Dietary PFHxA exposure did not result in measurable body burden and did not affect growth, fecundity, adult social perception behavior, or associative learning. PFHxA exposure did induce abnormal adult anxiety behaviors in the F0 generation that persisted transgenerationally in the F1 and F2. Abnormal larval and juvenile behavior was observed in the F1 generation, but not in the F2. PFHxA juvenile dietary exposure induced subtle and multigenerational behavior effects that warrant further investigation of this and other alternative short-chain PFAS.

The need to understand the biodegradation of oil and chemical dispersants in Arctic marine environments is increasing alongside growth in oil exploration and transport in the region. We chemically quantified biodegradation and abiotic losses of crude oil and Corexit 9500, when present separately, in incubations of Arctic seawater and identified microorganisms potentially involved in biodegradation of these substrates based on shifts in bacterial community structure (16S rRNA genes) and abundance of biodegradation genes (GeoChip 5.0 microarray). Incubations were performed over 28-day time courses using surface seawater collected from near-shore and offshore locations in the Chukchi Sea. Within 28 days, the indigenous microbial community biodegraded 36% (k = 0.010 day-1) and 41% (k = 0.014 day-1) of oil and biodegraded 77% and 33% (k = 0.015 day-1) of the Corexit 9500 component dioctyl sodium sulfosuccinate (DOSS) in respective near-shore and offshore incubations. Non-ionic surfactants (Span 80, Tween 80, and Tween 85) present in Corexit 9500 were non-detectable by 28 days due to a combination of abiotic losses and biodegradation. Microorganisms utilized oil and Corexit 9500 as growth substrates during the incubation, with the Corexit 9500 stimulating more extensive growth than oil within 28 days. Taxa known to include oil-degrading bacteria (e.g., Oleispira, Polaribacter, and Colwellia) and some oil biodegradation genes (e.g., alkB, nagG, and pchCF) increased in relative abundance in response to both oil and Corexit 9500. These results increase our understanding of oil and dispersant biodegradation in the Arctic and suggest that some bacteria may be capable of biodegrading both oil and Corexit 9500.

Hydrocarbon- and fluorocarbon-based surfactants are used in specialty or 'niche' chemical formulations that are designed for applications such as aircraft deicing and anti-icing, 'spreaders' that increase the effectiveness of pesticide formulations, and for fighting hydrocarbon-fuel fires. The identity of the surfactants in specialty formulations is usually proprietary information. However, this information is needed to design studies that monitor the occurrence and fate of all the components of specialty chemical formulations that enter the environment and pose a risk toward aquatic organisms. Fast atom bombardment/mass spectrometry (FAB/MS), while not a new technique, remains the fastest technique for identifying surfactants in complex mixtures because no sample preparation is required. FAB/MS was applied to samples of an aircraft deicer and anti-icer and aqueous-film-forming-foams (AFFF) for the purpose of identifying the major classes of hydrocarbon and fluorocarbon surfactants. High mass accuracy FAB/MS measurements were made to identify an unknown fluorosurfactant in an AFFF formulation. Rapid identification of surfactants that are released into the environment facilitates the subsequent selection of quantitative analytical methods that can be used to monitor the occurrence and fate of surfactants in the environment.

Fluorinated alkyl substances, which include perfluorooctane sulfonate (PFOS), constitute a diverse class of chemicals that occur in a wide range of products. Concern about the presence of fluorinated alkyl substances in the environment has increased since PFOS and related fluoroalkyl substances were detected in blood plasma of nonoccupationally exposed humans and in animal tissues collected from around the globe, including sparsely populated regions that have no apparent sources. PFOS was also found to exhibit both bioaccumulative and toxic properties. This review focuses on the analysis and occurrence of fluorinated alkyl substances that have been observed in the environment. Although fluorinated alkyl substances were identified and quantified in groundwaters, surface waters, wastewaters, and air samples, little is known about their transport or behavior in the environment. Numerous laboratory and field experiments are still needed to elucidate these processes. Additionally, techniques for efficiently treating wastewaters containing fluorinated alkyl substances must be found to prevent their release into the environment. [ABSTRACT FROM AUTHOR]

Background The World Health Organization (WHO) identifies climate change as one of the greatest health threats for humanity, with an estimated one in four deaths resulting from “extreme weather events heatwaves, storms and floods.” Severe acclimate weather creates “disruption in food systems, increases zoonoses and food-, water- and vector-borne diseases, and imposes challenges upon one’s own mental health.” As humans release more fossil fuels into earth’s atmosphere, it increases our planet’s temperature, including the frequency and severity of hurricanes, earthquakes, wildfires, and air pollution. This severe weather will harm “equal access to health care” and further impose “climate-sensitive” health risks on vulnerable populations, including “women, children, ethnic minorities, immigrants, low-income households, uninsured persons, diasporas, the elderly, and individuals with underlying health conditions.”Description The health care sector contributes approximately 8.5% of total U.S.-based greenhouse gas and is responsible for more than 4% of total global carbon emissions. If the health care sector were a country, it would be the world’s fifth-largest emitter of greenhouse gases. Emissions from health care facility operations, purchased energy, and the health care supply chain of goods and services are the biggest drivers of carbon emissions. Although each individual health care practice is only a tiny percentage of the sector’s emissions, there remain meaningful ways these facilities can contribute to collective efforts to reduce the industry’s impact on climate change by adopting more sustainable practices. This article provides health care professionals with recommendations that will enable them to serve as powerful advocates and change agents for environmental sustainability.