Next-generation PFAS 6:2 fluorotelomer sulfonate reduces plaque formation in exposed white-footed mice

Ecosystem-wide PFAS characterization and environmental behavior at a heavily contaminated desert oasis in the southwestern U.S

Record-high PFAS contamination levels were recently reported in birds and small mammals from Holloman Lake, a high-salinity wastewater oasis located in southern New Mexico, USA. We expanded the PFAS screening to surface water, soils, algae, invertebrates, fish, reptiles, and a larger number of plants, birds, and mammals to examine the fate, transport, and bioaccumulation of PFAS in the ecosystem and generate contamination profiles across both the water-land interface and multiple trophic levels. C5 and C6 perfluorocarboxylic acids, both of them known degradation products of 6:2 FTS, were the dominant PFAS in surface water in the lake. In contrast, perfluorooctanesulfonic acid (PFOS) was the main PFAS found in sediments along the shoreline, with the number of fluorinated carbons in the alkyl chain and clay minerals both appearing to play a key role in soil sorption. High soil PFAS concentrations up to 900 m from the edge of the water could not be explained by air transport of contaminated dust and instead seemed related to past inundation events involving contaminated water. Higher PFAS concentrations along the main body of the lake included an extraordinary 30,000 ng/g ww of PFOS recorded for a composite saltcedar (Tamarix sp.) tissue sample. Bioaccumulation pervaded the ecosystem's food webs and trophic levels, with PFAS detection in all species and all types of animal tissue (blood, liver, muscle, and bone). Contamination involved mainly PFOS, followed by perfluorohexanesulfonic acid (PFHxS), with the observed concentrations of PFAS increasing concomitantly among tissue types but the liver bioaccumulating at a faster rate.

Distribution and variability of per- and polyfluoroalkyl substances (PFASs) across three categories of wastewater treatment plants in Kaohsiung, the industrial hub of Taiwan

Paired surface wastewater samples from seven wastewater treatment plants (WWTPs) in Kaohsiung, Taiwan, were analyzed to quantify environmental PFAS loadings. Seventeen per- and poly-fluoroalkyl substances (PFASs) were analyzed, whereby WWTPs 1-4, treating domestic discharges, exhibited relatively low concentrations of 10.5-46.8 ng L-1. WWTP 5, handling mixed domestic and light industrial wastewater, had moderate levels of 45.7-102.3 ng L-1. WWTPs 6 and 7, which process heavy industrial discharges, recorded the highest PFAS concentrations of up to 2790 ng L-1 and 4290 ng L-1, respectively. The dominant PFAS compounds varied by facility: perfluoropentanoic acid (PFPeA) and 6:2 fluorotelomer sulfonate (6:2 FTS) in WWTPs 1-4, 6:2 FTS and perfluorooctanesulfonic acid (PFOS) in WWTPs 5, 6, and 7. Principal Component Analysis (PCA) confirmed that reverse osmosis (RO) effectively reduced PFAS concentrations, while conventional treatment processes lacked significant degradation capability. Three WWTPs (5-7) in Kaohsiung's heavily industrialized southern region had effluent PFAS levels exceeding the EPA lifetime health advisory limit of 70.0 ng L-1. These findings highlight the urgent need for advanced treatment technologies and provide essential data to support Taiwan EPA's PFAS management regulations in WWTPs.

Threshold for increased liver weight is protective of other effects in Peromyscus exposed to PFNA

Perfluorononanoic acid (PFNA) is a commercially relevant, long-chain (8 fully fluorinated carbon) perfluorinated carboxylic acid. PFNA has limited terrestrial ecotoxicity data and is detected in humans, animals, and the environment. This study is the fourth in a series with the objective of investigating the toxicity of a suite of per- and polyfluoroalkyl substances (PFAS) detected on military installations in a mammal indigenous to North America. Peromyscus leucopus (white-footed mice, ∼25/sex/dose) were exposed via oral gavage to either 0, 0.03, 0.14, 1, or 3 mg PFNA/kg-d for 112 consecutive days (4 wk premating exposure followed by an additional 12 wk of exposure after onset of mating). Parental generation animals were assessed for potential reproductive and developmental effects, organ weight changes, thyroid modulation, and immunotoxicity. Pup weight and survival were assessed at postnatal days 0, 1, 4, 7, and 10. Change in liver weight was determined to yield the most sensitive dose response according to benchmark dose analysis, and serves as the most protective point of departure (BMDL = 0.37 mg/kg-d PFNA). Other effects of PFNA exposure included reduced formation of plaque-forming cells, which are indicative of functional immune deficits (BMDL = 2.31 mg/kg-d); decreased serum thyroxine (BMDL = 0.93 mg/kg-d) without changes in some other hormones; and increased stillbirths (BMDL = 0.61 mg/kg-d PFNA). Pup weight and survival were not affected by PFNA exposure. Combined with data from previous studies, data from Peromyscus provide a One Health perspective on health effects of PFAS.

Changing the structure of PFOA and PFOS: a chemical industry strategy or a solution to avoid thyroid-disrupting effects?

BACKGROUND

The family of perfluoroalkyl and polyfluoroalkyl substances (PFAS) raised concern for their proven bioaccumulation and persistence in the environment and animals as well as for their hazardous health effects. As a result, new congeners of PFAS have rapidly replaced the so-called "old long-chain PFAS" (mainly PFOA and PFOS), currently out-of-law and banned by most countries. These compounds derive from the original structure of "old long-chain PFAS", by cutting or making little conformational changes to their structure, thus obtaining new molecules with similar industrial applications. The new congeners were designed to obtain "safer" compounds. Indeed, old-long-chain PFAS were reported to exert thyroid disruptive effects in vitro, and in vivo in animals and humans. However, shreds of evidence accumulated so far indicate that the "restyling" of the old PFAS leads to the production of compounds, not only functionally similar to the previous ones but also potentially not free of adverse health effects and bioaccumulation. Studies aimed at characterizing the effects of new-PFAS congeners on thyroid function indicate that some of these new-PFAS congeners showed similar effects.

PURPOSE

The present review is aimed at providing an overview of recent data regarding the effects of novel PFAS alternatives on thyroid function.

RESULTS AND CONCLUSIONS

An extensive review of current legislation and of the shreds of evidence obtained from in vitro and in vivo studies evaluating the effects of the exposure to novel PFOA and PFOS alternatives, as well as of PFAS mixture on thyroid function will be provided.

Extraordinary levels of per- and polyfluoroalkyl substances (PFAS) in vertebrate animals at a New Mexico desert oasis: Multiple pathways for wildlife and human exposure

Per- and polyfluoroalkyl substances (PFAS) in the environment pose persistent and complex threats to human and wildlife health. Around the world, PFAS point sources such as military bases expose thousands of populations of wildlife and game species, with potentially far-reaching implications for population and ecosystem health. But few studies shed light on the extent to which PFAS permeate food webs, particularly ecologically and taxonomically diverse communities of primary and secondary consumers. Here we conducted >2000 assays to measure tissue-concentrations of 17 PFAS in 23 species of mammals and migratory birds at Holloman Air Force Base (AFB), New Mexico, USA, where wastewater catchment lakes form biodiverse oases. PFAS concentrations were among the highest reported in animal tissues, and high levels have persisted for at least three decades. Twenty of 23 species sampled at Holloman AFB were heavily contaminated, representing middle trophic levels and wetland to desert microhabitats, implicating pathways for PFAS uptake: ingestion of surface water, sediments, and soil; foraging on aquatic invertebrates and plants; and preying upon birds or mammals. The hazardous long carbon-chain form, perfluorooctanosulfonic acid (PFOS), was most abundant, with liver concentrations averaging >10,000 ng/g wet weight (ww) in birds and mammals, respectively, and reaching as high 97,000 ng/g ww in a 1994 specimen. Perfluorohexanesulfonic acid (PFHxS) averaged thousands of ng/g ww in the livers of aquatic birds and littoral-zone house mice, but one order of magnitude lower in the livers of upland desert rodent species. Piscivores and upland desert songbirds were relatively uncontaminated. At control sites, PFAS levels were strikingly lower on average and different in composition. In sum, legacy PFAS at this desert oasis have permeated local aquatic and terrestrial food webs across decades, severely contaminating populations of resident and migrant animals, and exposing people via game meat consumption and outdoor recreation.

Reproductive and immune effects emerge at similar thresholds of PFHxS in deer mice

Although perfluorohexane sulfonate (PFHxS) is structurally similar to perfluorooctane sulfonate (PFOS) and also widely detected in humans and the environment, comparatively fewer toxicity data exists on this 6-chain perfluoroalkyl sulfonic acid. In this study, repeated oral doses of PFHxS were administered to deer mice (Peromyscus maniculatus) to evaluate subchronic toxicity and potential effects on reproduction and development. Maternal oral exposure to PFHxS caused increased stillbirths, which is relevant for ecological risk assessment, and resulted in a benchmark dose lower limit (BMDL) of 5.72 mg/kg-d PFHxS. Decreased plaque formation, which is relevant for human health risk assessment, occurred in both sexes of adult animals (BMDL = 8.79 mg/kg-d PFHxS). These data are the first to suggest a direct link between PFHxS and decreased functional immunity in an animal model. Additionally, female animals exhibited increased liver:body weight and animals of both sexes exhibited decreased serum thyroxine (T4) levels. Notably, since reproductive effects were used to support 2016 draft health advisories and immune effects were used in 2022 drinking water health advisories released by the United States Environmental Protection Agency for PFOS and perfluorooctanoic acid (PFOA), these novel data can potentially support advisories for PFHxS because relevant points of departure emerge at similar thresholds in a wild mammal and corroborate the general understanding of per- and polyfluoroalkyl substances (PFAS).