Per- and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

Investigation of pH-dependent extraction methods for PFAS in (fluoropolymer-based) consumer products: A comparative study between targeted and sum parameter analysis

Here, we report a comparative study of different sum parameter analysis methods for the extraction of per- and polyfluoroalkyl substances (PFAS) from manufactured consumer products, which can be measured by combustion ion chromatography (CIC). Therefore, a hydrolysis-based extraction method was further developed, which accounts for the addition of hydrolyzable covalently bound polyfluoroalkylated side-chain polymers (SFPs) to the extractable organic fluorine portion of the mass balance proposed as "hydrolyzable organically bound fluorine" (HOF). To test this hypothesis, the method was applied to 39 different consumer products containing fluoropolymers or monomeric PFAS taken from four different categories: outdoor textiles, paper packaging, carpeting, and permanent baking sheets. We also evaluated the method's efficiency by extracting four synthesized fluorotelomer polyacrylate reference compounds. The total fluorine (TF) and extractable organically bound fluorine (EOF) values were measured through CIC using established protocols. The TF values ranged from sub-ppb to %-levels, depending on the compound class. All samples showed results for hydrolyzed organofluorine (HOF) between 0.03 and 76.3 μg/g, while most EOF values were lower ( Collapse

Key Words

• Combustion ion chromatography (CIC)
• Extractable organically bound fluorine (EOF)
• Hydrolytic extraction
• Per- and polyfluoroalkyl substances (PFAS) sum parameter
• Side-chain fluorinated polymers (SFPs)
• Solid-liquid extraction

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MESH Headings

• Fluorocarbon Polymers/analysis
• Fluorocarbons/analysis
• Chromatography, Liquid
• Fluorine/chemistry
• Tandem Mass Spectrometry
• Hydrogen-Ion Concentration

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Affiliation(s)

Philipp Roesch Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany.
Andrea Schinnen Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany
Maren Riedel Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany
Thomas Sommerfeld Federal Institute for Materials Research and Testing, Division 1.7 - Organic Trace and Food Analysis, Richard-Willstätter-Straße 11, 12489, Berlin, Germany
George Sawal German Environment Agency, Colditzstr. 34, 12099, Berlin, Germany
Nicole Bandow German Environment Agency, Colditzstr. 34, 12099, Berlin, Germany
Christian Vogel Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany
Ute Kalbe Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany
Franz-Georg Simon Federal Institute for Materials Research and Testing, Division 4.3 - Contaminant Transfer and Environmental Technologies, Unter den Eichen 87, 12205, Berlin, Germany

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Comparative hepatotoxicity of novel lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, ie. HQ-115) and legacy Perfluorooctanoic acid (PFOA) in male mice: Insights into epigenetic mechanisms and pathway-specific responses

Lithium Bis(trifluoromethanesulfonyl)imide (LiTFSI ie. HQ-115), a polymer electrolyte used in energy applications, has been detected in the environment, yet its health risks and environmental epigenetic effects remain unknown. This study aims to unravel the potential health risks associated with LiTFSI, investigate the role of DNA methylation-induced toxic mechanisms in its effects, and compare its hepatotoxic impact with the well-studied Perfluorooctanoic Acid (PFOA). Using a murine model, six-week-old male CD1 mice were exposed to 10 and 20 mg/kg/day of each chemical for 14 days as 14-day exposure and 1 and 5 mg/kg/day for 30 days as 30-day exposure. Results indicate that PFOA exposure induced significant hepatotoxicity, characterized by liver enlargement, and elevated serum biomarkers. In contrast, LiTFSI exposure showed lower hepatotoxicity, accompanied by mild liver injuries. Despite higher bioaccumulation of PFOA in serum, LiTFSI exhibited a similar range of liver concentrations compared to PFOA. Reduced Representative Bisulfite Sequencing (RRBS) analysis revealed distinct DNA methylation patterns between 14-day and 30-day exposure for the two compounds. Both LiTFSI and PFOA implicated liver inflammatory pathways and lipid metabolism. Transcriptional results showed that differentially methylated regions in both exposures are enriched with cancer/disease-related motifs. Furthermore, Peroxisome proliferator-activated receptor alpha (PPARα), a regulator of lipid metabolism, was upregulated in both exposures, with downstream genes indicating potential oxidative damages. Overall, LiTFSI exhibits distinct hepatotoxicity profiles, emphasizing the need for comprehensive assessment of emerging PFAS compounds.

Exposure to perfluoroalkyl substances and longitudinal changes in bone mineral density in adolescents and young adults: A multi-cohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may impair bone development in adolescence, which impacts life-long bone health. No previous studies have examined prospective associations of individual PFAS and their mixture with bone mineral density (BMD) changes in Hispanic young persons, a population at high risk of osteoporosis in adulthood.

OBJECTIVES

To examine associations of individual PFAS and PFAS mixtures with longitudinal changes in BMD in an adolescent Hispanic cohort and examine generalizability of findings in a mixed-ethnicity young adult cohort (58.4% Hispanic).

METHODS

Overweight/obese adolescents from the Study of Latino Adolescents at Risk of Type 2 Diabetes (SOLAR; n = 304; mean follow-up = 1.4 years) and young adults from the Southern California Children's Health Study (CHS; n = 137; mean follow-up = 4.1 years) were included in this study. Plasma PFAS were measured at baseline and dual x-ray absorptiometry scans were performed at baseline and follow-up to measure BMD. We estimated longitudinal associations between BMD and five PFAS via separate covariate-adjusted linear mixed effects models, and between BMD and the PFAS mixture via quantile g-computation.

RESULTS

In SOLAR adolescents, baseline plasma perfluorooctanesulfonic acid (PFOS) was associated with longitudinal changes in BMD. Each doubling of PFOS was associated with an average -0.003 g/cm2 difference in change in trunk BMD per year over follow-up (95% CI: -0.005, -0.0002). Associations with PFOS persisted in CHS young adults, where each doubling of plasma PFOS was associated with an average -0.032 g/cm2 difference in total BMD at baseline (95% CI -0.062, -0.003), though longitudinal associations were non-significant. We did not find associations of other PFAS with BMD; associations of the PFAS mixture with BMD outcomes were primarily negative though non-significant.

DISCUSSION

PFOS exposure was associated with lower BMD in adolescence and young adulthood, important periods for bone development, which may have implications on future bone health and risk of osteoporosis in adulthood.

The U.S. PFAS exposure burden calculator for 2017-2018: Application to the HOME Study, with comparison of epidemiological findings from NHANES

BACKGROUND

The 2017-2018 U.S. PFAS exposure burden calculator was designed to provide a summary exposure score for per- and polyfluoroalkyl substances (PFAS) mixtures using targeted PFAS analyte data. Its aim was to place PFAS burden score estimates onto a common scale based on nationally representative U.S. reference ranges from 2017 to 2018, enabling comparisons of overall PFAS burden scores across studies even if they did not measure the same set of PFAS analytes.

OBJECTIVE

To use the U.S. PFAS exposure burden calculator for comparing the same mixture of PFAS compounds in similarly aged adolescents and their associations with cardiometabolic outcomes in the HOME Study and NHANES between 2015 and 2018.

METHODS

We applied the PFAS burden calculator to 8 PFAS analytes measured in the serum of adolescents from the HOME Study (Cincinnati, Ohio; age range 11-14 years; years: 2016-2019; n = 207) and NHANES (US; age range 12-14 years; years 2015-2018; n = 245). We used the non-parametric Mann-Whitney U test and chi-squared test to compare the two study samples. In both studies, we examined associations of PFAS burden scores with the same cardiometabolic outcomes, adjusted for the same core set of covariates using regression analyses. We conducted sensitivity analyses to verify robustness of exposure-outcome associations, by accounting for measurement error of PFAS burden scores.

RESULTS

PFAS burden scores were significantly different (p = 0.004) between the HOME Study (median: 0.00, interquartile range - 0.37, 0.34) and the NHANES samples (median: 0.04, IQR -0.11, 0.54), while no significant difference was found for PFAS summed concentrations (p = 0.661). In the HOME Study, an interquartile (IQR) increase in PFAS burden score was associated with higher total cholesterol [7.0 mg/dL, 95% CI: 0.6, 13.4]; HDL [2.8 mg/dL, 95% CI: 0.4, 5.2]; LDL [5.9 mg/dL, 95% CI: 0.5, 11.3], insulin [0.1 log(mIU/L), 95% CI: 0.01, 0.2], and HOMA-IR [0.1, 95% CI: 0.01, 0.2]. In NHANES, an IQR increase in PFAS burden score was associated with higher diastolic blood pressure [2.4 mmHg, 95% CI: 0.4, 4.4] but not with other outcomes. Sensitivity analyses in the HOME Study and NHANES were consistent with the main findings.

CONCLUSIONS

Performance of the U.S. PFAS exposure burden calculator was similar in a local versus national sample of adolescents, and may be a useful tool for the assessment of PFAS mixtures across studies.

Toxic Ingredients in Personal Care Products: A Dermatological Perspective

Environmental dermatology is the study of how environmental factors affect the integumentary system. The environment includes natural and built habitats, encompassing ambient exposure, occupational exposures, and lifestyle exposures secondary to dietary and personal care choices. This review explores common toxins found in personal care products and packaging, such as bisphenols, parabens, phthalates, per- and poly-fluoroalkyl substances, p-phenylenediamine, and formaldehyde. Exposure to these toxins has been associated with carcinogenic, obesogenic, or proinflammatory effects that can potentiate disease. In addition, these compounds have been implicated as endocrine-disrupting chemicals that can worsen dermatological conditions such as acne vulgaris, or dermatitis. Certain pollutants found in personal care products are not biodegradable and have the potential to bioaccumulate in humans. Therefore, even short-term exposure can cause long-lasting issues for communities. The skin is often the first point of contact for environmental exposures and serves as the conduit between environmental toxins and the human body. Therefore, it is important for dermatologists to understand common pollutants and their acute, subacute, and chronic impact on dermatological conditions to better diagnose and manage disease.

Per- and polyfluoroalkyl substances, polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers and dysregulation of MicroRNA expression in humans and animals-A systematic review

BACKGROUND

Persistent organic pollutants (POPs) are chemicals characterized by their environmental persistence. Evidence suggests that exposure to POPs, which is ubiquitous, is associated with microRNA (miRNA) dysregulation. miRNA are key regulators in many physiological processes. It is thus of public health concern to understand the relationships between POPs and miRNA as related to health outcomes.

OBJECTIVES

This systematic review evaluated the relationship between widely recognized, intentionally manufactured, POPs, including per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (dichlorodiphenyltrichloroethane [DDT], dichlorodiphenyldichloroethylene [DDE], hexachlorobenzene [HCB]), with miRNA expression in both human and animal studies.

METHODS

We used PubMed and Embase to systematically search the literature up to September 29th, 2023. Search results for human and animal studies were included if they incorporated at least one POP of interest in relation to at least one miRNA. Data were synthesized to determine the direction and significance of associations between POPs and miRNA. We utilized ingenuity pathway analysis to review disease pathways for miRNA that were associated with POPs.

RESULTS

Our search identified 38 eligible studies: 9 in humans and 29 in model organisms. PFAS were associated with decreased expression of miR-19, miR-193b, and miR-92b, as well as increased expression of miR-128, miR-199a-3p, and miR-26b across species. PCBs were associated with increased expression of miR-15a, miR-1537, miR-21, miR-22-3p, miR-223, miR-30b, and miR-34a, as well as decreased expression of miR-130a and let-7b in both humans and animals. Pathway analysis for POP-associated miRNA identified pathways related to carcinogenesis.

DISCUSSION

This is the first systematic review of the association of POPs with miRNA in humans and model organisms. Large-scale prospective human studies are warranted to examine the role of miRNA as mediators between POPs and health outcomes.

Hazard and risk characterization of 56 structurally diverse PFAS using a targeted battery of broad coverage assays using six human cell types

Per- and poly-fluoroalkyl substances (PFAS) are extensively used in commerce leading to their prevalence in the environment. Due to their chemical stability, PFAS are considered to be persistent and bioaccumulative; they are frequently detected in both the environment and humans. Because of this, PFAS as a class (composed of hundreds to thousands of chemicals) are contaminants of very high concern. Little information is available for the vast majority of PFAS, and regulatory agencies lack safety data to determine whether exposure limits or restrictions are needed. Cell-based assays are a pragmatic approach to inform decision-makers on potential health hazards; therefore, we hypothesized that a targeted battery of human in vitro assays can be used to determine whether there are structure-bioactivity relationships for PFAS, and to characterize potential risks by comparing bioactivity (points of departure) to exposure estimates. We tested 56 PFAS from 8 structure-based subclasses in concentration response (0.1-100 μM) using six human cell types selected from target organs with suggested adverse effects of PFAS - human induced pluripotent stem cell (iPSC)-derived hepatocytes, neurons, and cardiomyocytes, primary human hepatocytes, endothelial and HepG2 cells. While many compounds were without effect; certain PFAS demonstrated cell-specific activity highlighting the necessity of using a compendium of in vitro models to identify potential hazards. No class-specific groupings were evident except for some chain length- and structure-related trends. In addition, margins of exposure (MOE) were derived using empirical and predicted exposure data. Conservative MOE calculations showed that most tested PFAS had a MOE in the 1-100 range; ∼20% of PFAS had MOE<1, providing tiered priorities for further studies. Overall, we show that a compendium of human cell-based models can be used to derive bioactivity estimates for a range of PFAS, enabling comparisons with human biomonitoring data. Furthermore, we emphasize that establishing structure-bioactivity relationships may be challenging for the tested PFAS.

Exploring the Potential Link between PFAS Exposure and Endometrial Cancer: A Review of Environmental and Sociodemographic Factors

This exploratory narrative review paper delves into the intricate interplay between per- and polyfluoroalkyl substances (PFAS) exposure, sociodemographic factors, and the influence of stressors in the context of endometrial cancer. PFAS, ubiquitous environmental contaminants notorious for their persistence in the ecosystem, have garnered attention for their potential to disrupt endocrine systems and provoke immune responses. We comprehensively examine the various sources of PFAS exposure, encompassing household items, water, air, and soil, thus shedding light on the multifaceted routes through which individuals encounter these compounds. Furthermore, we explore the influence of sociodemographic factors, such as income, education, occupation, ethnicity/race, and geographical location and their relationship to endometrial cancer risk. We also investigated the role of stress on PFAS exposure and endometrial cancer risk. The results revealed a significant impact of sociodemographic factors on both PFAS levels and endometrial cancer risk. Stress emerged as a notable contributing factor influencing PFAS exposure and the development of endometrial cancer, further emphasizing the importance of stress management practices for overall well-being. By synthesizing evidence from diverse fields, this review underscores the need for interdisciplinary research and targeted interventions to comprehensively address the complex relationship between PFAS, sociodemographic factors, stressors, and endometrial cancer.

Characterizing Volatile Emissions and Combustion Byproducts from Aqueous Film-Forming Foams Using Online Chemical Ionization Mass Spectrometry

Aqueous film-forming foams (AFFFs) are used in firefighting applications and often contain per- and polyfluoroalkyl substances (PFAS), which can detrimentally impact environmental and biological health. Incineration is a potential disposal method for AFFFs, which may produce secondary PFAS and other air pollutants. We used online chemical ionization mass spectrometry (CIMS) to measure volatile PFAS emissions from incinerating AFFF concentrate solutions. We quantified perfluorinated carboxylic acids (PFCAs) during the incineration of legacy and contemporary AFFFs. These included trifluoroacetic acid, which reached mg m-3 quantities in the incinerator exhaust. These PFCAs likely arose as products of incomplete combustion of AFFF fluorosurfactants with lower peak furnace temperatures yielding higher PFCA concentrations. We also detected other short-chain PFAS, and other novel chemical products in AFFF combustion emissions. The volatile headspace above AFFF solutions contained larger (C ≥ 8), less oxidized PFAS detected by CIMS. We identified neutral PFAS resembling fluorotelomer surfactants (e.g., fluorotelomer sulfonamide alkylbetaines and fluorotelomer thioether amido sulfonates) and fluorotelomer alcohols in contemporary AFFF headspaces. Directly comparing the distinct chemical spaces of AFFF volatile headspace and combustion byproducts as measured by CIMS provides insight toward the chemistry of PFAS during thermal treatment of AFFFs.

HNF4A as a potential target of PFOA and PFOS leading to hepatic steatosis: Integrated molecular docking, molecular dynamic and transcriptomic analyses

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are indeed among the most well known and extensively studied Per- and polyfluoroalkyl substances (PFASs), and increasing evidence confirm their effects on human health, especially liver steatosis. Nonetheless, the molecular mechanisms of their initiation of hepatic steatosis is still elusive. Therefore, potential targets of PFOA/PFOS must be explored to ameliorate its adverse consequences. This research aims to investigate the molecular mechanisms of PFOA and PFOS-induced liver steatosis, with emphasis on identifying a potential target that links these PFASs to liver steatosis. The potential target that causes PFOA and PFOS-induced liver steatosis have been explored and determined based on molecular docking, molecular dynamics (MD) simulation, and transcriptomics analysis. In silico results show that PFOA/PFOS can form a stable binding conformation with HNF4A, and PFOA/PFOS may interact with HNF4A to affect the downstream conduction mechanism. Transcriptome data from PFOA/PFOS-induced human stem cell spheres showed that HNF4A was inhibited, suggesting that PFOA/PFOS may constrain its function. PFOS mainly down-regulated genes related to cholesterol synthesis while PFOA mainly up-regulated genes related to fatty acid β-oxidation. This study explored the toxicological mechanism of liver steatosis caused by PFOA/PFOS. These compounds might inhibit and down-regulate HNF4A, which is the molecular initiation events (MIE) that induces liver steatosis.

Understanding the effects of per- and polyfluoroalkyl substances on early skin development: Role of ciliogenesis inhibition and altered microtubule dynamics

Per- and polyfluoroalkyl substances (PFAS) are a class of highly stable chemicals, widely used in everyday products, and widespread in the environment, even in pregnant women. While epidemiological studies have linked prenatal exposure to PFAS with atopic dermatitis in children, little is known about their toxic effects on skin development, especially during the embryonic stage. In this study, we utilized human embryonic stem cells to generate non-neural ectoderm (NNE) cells and exposed them to six PFAS (perfluorooctanoic acid (PFOA), undecafluorohexanoic acid (PFHxA), heptafluorobutyric acid (PFBA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorobutyric acid (PFBS)) during the differentiation process to assess their toxicity to early skin development. Our results showed that PFOS altered the spindle-like morphology of NNE cells to a pebble-like morphology, and disrupted several NNE markers, including KRT16, SMYD1, and WISP1. The six PFAS had a high potential to cause hypohidrotic ectodermal dysplasia (HED) by disrupting the expression levels of HED-relevant genes. Transcriptomic analysis revealed that PFOS treatment produced the highest number (1156) of differentially expressed genes (DEGs) among the six PFAS, including the keratinocyte-related genes KRT6A, KRT17, KRT18, KRT24, KRT40, and KRT81. Additionally, we found that PFOS treatment disturbed several signaling pathways that are involved in regulating skin cell fate decisions and differentiation, including TGF-β, NOTCH, Hedgehog, and Hippo signaling pathways. Interestingly, we discovered that PFOS inhibited, by partially interfering with the expression of cytoskeleton-related genes, the ciliogenesis of NNE cells, which is crucial for the intercellular transduction of the above-mentioned signaling pathways. Overall, our study suggests that PFAS can inhibit ciliogenesis and hamper the transduction of important signaling pathways, leading potential congenital skin diseases. It sheds light on the underlying mechanisms of early embryonic skin developmental toxicity and provides an explanation for the epidemiological data on PFAS. ENVIRONMENTAL IMPLICATION: We employed a model based on human embryonic stem cells to demonstrate that PFOS has the potential to elevate the risk of hypohidrotic ectodermal dysplasia. This is achieved by targeting cilia, inhibiting ciliogenesis, and subsequently disrupting crucial signaling pathways like TGF-β, NOTCH, Hedgehog, and Hippo, during the early phases of embryonic skin development. Our study highlights the dangers and potential impacts of six PFAS pollutants on human skin development. Additionally, we emphasize the importance of closely considering PFHxA, PFBA, PFHxS, and PFBS, as they have shown the capacity to modify gene expression levels, albeit to a lesser degree.

Mechanistic exploration of polytetrafluoroethylene thermal plasma gasification through multiscale simulation coupled with experimental validation

The ever-growing quantities of persistent Polytetrafluoroethylene (PTFE) wastes, along with consequential ecological and human health concerns, stimulate the need for alternative PTFE disposal method. The central research challenge lies in elucidating the decomposition mechanism of PTFE during high-temperature waste treatment. Here, we propose the PTFE microscopic thermal decomposition pathways by integrating plasma gasification experiments with multi-scale simulations strategies. Molecular dynamic simulations reveal a pyrolysis-oxidation & chain-shortening-deep defluorination (POCD) degradation pathway in an oxygen atmosphere, and an F abstraction-hydrolysis-deep defluorination (FHD) pathway in a steam atmosphere. Density functional theory computations demonstrate the vital roles of 1O2 and ·H radicals in the scission of PTFE carbon skeleton, validating the proposed pathways. Experimental results confirm the simulation results and show that up to 80.12% of gaseous fluorine can be recovered through plasma gasification within 5 min, under the optimized operating conditions determined through response surface methodology.

A review of frustrated Lewis pair enabled monoselective C-F bond activation

Frustrated Lewis pair (FLP) bond activation chemistry has greatly developed over the last two decades since the seminal report of metal-free reversible hydrogen activation. Recently, FLP systems have been utilized to allow monoselective C-F bond activation (at equivalent sites) in polyfluoroalkanes. The problem of 'over-defluorination' in the functionalization of polyfluoroalkanes (where multiple fluoro-positions are uncontrollably functionalized) has been a long-standing chemical problem in fluorocarbon chemistry for over 80 years. FLP mediated monoselective C-F bond activation is complementary to other solutions developed to address 'over-defluorination' and offers several advantages and unique opportunities. This perspective highlights some of these advantages and opportunities and places the development of FLP mediated C-F bond activation into the context of the wider effort to overcome 'over-defluorination'.

Studying mixture effects on uptake and tissue distribution of PFAS in zebrafish (Danio rerio) using physiologically based kinetic (PBK) modelling

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in the aquatic environment. They include persistent, mobile, bioaccumulative, and toxic chemicals and it is therefore critical to increase our understanding on their adsorption, distribution, metabolism, excretion (ADME). The current study focused on uptake of seven emerging PFAS in zebrafish (Danio rerio) and their potential maternal transfer. In addition, we aimed at increasing our understanding on mixture effects on ADME by developing a physiologically based kinetic (PBK) model capable of handling co-exposure scenarios of any number of chemicals. All studied chemicals were taken up in the fish to varying degrees, whereas only perfluorononanoate (PFNA) and perfluorooctanoate (PFOA) were quantified in all analysed tissues. Perfluorooctane sulfonamide (FOSA) was measured at concerningly high concentrations in the brain (Cmax over 15 μg/g) but also in the liver and ovaries. All studied PFAS were maternally transferred to the eggs, with FOSA and 6:2 perfluorooctane sulfonate (6,2 FTSA) showing significant (p < 0.02) signs of elimination from the embryos during the first 6 days of development, while perfluorobutane sulfonate (PFBS), PFNA, and perfluorohexane sulfonate (PFHxS) were not eliminated in embryos during this time-frame. The mixture PBK model resulted in >85 % of predictions within a 10-fold error and 60 % of predictions within a 3-fold error. At studied levels of PFAS exposure, competitive binding was not a critical factor for PFAS kinetics. Gill surface pH influenced uptake for some carboxylates but not the sulfonates. The developed PBK model provides an important tool in understanding kinetics under complex mixture scenarios and this use of New Approach Methodologies (NAMs) is critical in future risk assessment of chemicals and early warning systems.

Per- and polyfluoroalkyl substances (PFAS) in Canadian municipal wastewater and biosolids: Recent patterns and time trends 2009 to 2021

The concentrations of per- and polyfluoroalkyl substances (PFAS) were determined in raw influent, final effluent, and treated biosolids at Canadian wastewater treatment plants (WWTPs) to evaluate the fate of PFAS through liquid and solids trains of typical treatment process types used in Canada and to assess time trends of PFAS in wastewater between 2009 and 2021. Data for 42 PFAS in samples collected from 27 WWTP across Canada were used to assess current concentrations and 48 WWTPs were included in the time trends analysis. Although regulated and phased-out of production by industry since the early 2000s and late 2000s/early2010s, respectively, perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and other long-chain PFAS continue to be widely detected in Canadian wastewater and biosolids. Short-chain PFAS that are not currently regulated in Canada were also widely detected. In general, elevated concentrations of several PFAS were observed at WWTPs that receive landfill leachate. Except for PFOS, concentrations of long-chain perfluoroalkyl carboxylates (PFCAs) and perfluoroalkane sulfonates (PFSAs) generally decreased over time in influent, effluent, and biosolids, which is attributable to industrial production phase-outs and regulations. Concentrations of PFOS did not decrease over time in wastewater media. This indicates that regulatory action and industrial phase-outs of PFOS are slow to be reflected in wastewater. Concentrations of short-chain PFCAs in wastewater influent and effluent consistently increased between 2009 and 2021, which reflect the use of short-chain PFAS as replacements for phased-out and regulated longer-chained PFAS. Short-chain PFAS were infrequently detected in biosolids. Continued periodic monitoring of PFAS in wastewater matrices in Canada and throughout the world is recommended to track the effectiveness of regulatory actions, particularly activities to address the broad class of PFAS.

Assessing construction and demolition wood-derived biochar for in-situ per- and polyfluoroalkyl substance (PFAS) removal from landfill leachate

With regulations for per-and polyfluoroalkyl substances (PFAS) impending, the abundance of these chemicals of emerging concern in municipal solid waste (MSW) landfill leachate increasingly challenges landfill operators to seek on-site leachate pre-treatment options. This two-staged study explores the potential reuse of biochar derived from construction and demolition debris (CDD) wood as an in-situ PFAS sorbent for application within MSW landfill leachate collection systems. Batch leaching tests were first used to examine the feasibility of capturing PFAS from landfill leachate using two sources of CDD-wood-derived biochar. Then, columns were used to test the in-situ sorption capabilities of the same biochars under simulated landfill conditions. All leachates were characterized for pH, chemical oxygen demand, ammonia-nitrogen, and 92 PFAS. Seventeen PFAS were detected in the batch leaching experiment, and nine PFAS were detected in column leachates. In the batch leaching scenario, Biochar 1 achieved a maximum of 29% PFAS reduction compared to controls. Columns containing Biochar 1 generated leachates with PFAS concentrations 50% to 80% higher than those in control columns for the duration of the experiment. Columns containing Biochar 2 generated leachates with PFAS concentrations 44% less than controls in week 1 and similar concentrations in weeks 2, 3, and 4. In this study, PFAS removal from landfill leachate using biochar derived from CDD wood was not significant. Further research on biochar derived from CDD wood is needed before it can be recommended as an in-situ landfill leachate pre-treatment method.

Are Chinese mitten crabs (Eriocheir sinensis) suitable as biomonitor or bioindicator of per- and polyfluoroalkyl substances (PFAS) pollution?

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment. In Flanders, the bioaccumulation in aquatic organisms is currently being monitored using European perch and European eel. Since both are native species, there is an ethical need to search for other suitable biomonitors. This study aims to investigate whether the invasive Chinese mitten crab could be used in biomonitoring programs by assessing PFAS accumulation in hepatopancreas, muscle tissue, and carapace. Furthermore, we correlated accumulated concentrations to those in the local abiotic environment. Concentrations in the crabs (highest average ∑PFAS concentration of 688 ± 505 ng/g ww) were often higher than those in crab species from other regions across the globe, confirming that Flanders is highly polluted with PFAS. Concentrations in the crabs did not reflect those in the abiotic environment. This implies that biomonitoring is necessary to investigate the impact of PFAS pollution on organisms in aquatic ecosystems, as important data is missing when only the abiotic environment is monitored. The accumulation profiles differed between the invasive crab and the native European perch and European eel, potentially due to a different ecology and trophic position. Since all three species provide complementary information on the PFAS pollution, a multi-species approach in biomonitoring is recommended. Overall, our results show that the crabs can be used as biomonitor, but more information is necessary to confirm their suitability as bioindicator.

Micropollutants in biochar produced from sewage sludge: A systematic review on the impact of pyrolysis operating conditions

Biochar obtained from sewage sludge serves as a valuable soil amendment in agriculture, enhancing soil properties by increasing the nutrient content, cation exchange capacity, water retention, and oxygen transmission. However, its utilisation is hampered by the presence of micropollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and volatile organic compounds (VOCs). Previous studies indicate that the type and amount of micropollutants can be significantly adjusted by selecting the right process parameters. This literature review provides an overview of how (1) pyrolysis temperature, (2) carrier gas flow and type, (3) heating rate, and (4) residence time affect the concentration of micropollutants in biochar produced from sewage sludge. The micropollutants targeted are those listed by the European Biochar Certificate (EBC) and by the International Biochar Institution (IBI), including PAHs, PCDD/Fs, PCBs and VOCs. In addition, per- and poly-fluoroalkyl substances (PFAS) are also considered due to their presence in sewage sludge. The findings suggest that higher pyrolysis temperatures reduce micropollutant levels. Moreover, the injection of a carrier gas (N2 or CO2) during the pyrolysis and cooling processes effectively lowers PAHs and PCDD/Fs, by reducing the contact of biochar with oxygen, which is crucial in mitigating micropollutants. Nevertheless, limited available data impedes an assessment of the impact of these parameters on PFAS in biochar. In addition, further research is essential to understand the effects of carrier gas type, heating rate, and residence time in order to determine the optimal pyrolysis process parameters for generating clean biochar.

Detection, Quantification, and Isomer Differentiation of Per- and Polyfluoroalkyl Substances (PFAS) Using MALDI-TOF with Trapped Ion Mobility

Per- and polyfluoroalkyl substances (PFAS) are a class of organic compounds that have attracted global attention for their persistence in the environment, exposure to biological organisms, and their adverse health effects. There is an urgent need to develop analytical methodologies for the characterization of PFAS in various sample matrices. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) represents a chromatography-free MS method that performs laser-based ionization and in situ analysis on samples. In this study, we present PFAS analysis by MALDI-time-of-flight (TOF) MS with trapped ion mobility spectrometry (TIMS), which provides an additional dimension of gas phase separation based on the size-to-charge ratios. MALDI matrix composition and key instrument parameters were optimized to produce different ranges of calibration curves. Parts per billion (ppb) range of calibration curves were achieved for a list of legacy and alternative perfluorosulfonic acids (PFSAs) and perfluorocarboxylic acids (PFCAs), while ion mobility spectrum filtering enabled parts per trillion (ppt) range of calibration curves for PFSAs. We also successfully demonstrated the separation of three perfluorooctanesulfonic acid (PFOS) structural isomers in the gas phase using TIMS. Our results demonstrated the new development of utilizing MALDI-TOF-MS coupled with TIMS for fast, quantitative, and sensitive analysis of PFAS, paving ways to future high-throughput and in situ analysis of PFAS such as MS imaging applications.

Persistent Organic Pollutants in Austrian Human Breast Milk Collected between 2013 and 2016

Breast milk holds an immense nutritional value as it contains health-promoting substances in a unique, optimal form. Additionally, breast milk's significance extends to health and environmental protection, as it serves as an indicator of both maternal and infant exposure. In this study, breast milk samples collected in 2013 and in 2014-2016 from mothers in Vienna (Austria) were analysed for polybrominated diphenyl ethers (PBDE) and per- and polyfluoroalkyl substances (PFAS), as well as further substances which have been listed under the Stockholm Convention on Persistent Organic Pollutants (POPs) due to their persistent, bioaccumulative and toxic properties. The total concentration of the PBDE congeners in the samples (n = 18, sampled 2013) ranged from 0.055 to 52 ng/g lipid, and from 0.002 to 2.5 ng/g breast milk. In the pooled sample, the sum of PBDEs was detected at a level of 4.4 ng/g lipid. Based on the 2014-2016 study population, certain PFAS were detected in all samples (n = 40). Exposure to the sum of four specific PFAS including perfluorooctanesulphonate (PFOS), perfluorooctanoic acid (PFOA), perfluoro-n-nonanoic acid (PFNA) and perfluoro-1-hexanesulfonate (PFHxS) ranged between 0.014 and 0.12 ng/L breast milk. In the pooled sample, PFOS and PFOA were found in concentrations of 0.025 ng/g and of 0.045 ng/g, respectively. In addition, the first generation of POPs, mainly organochlorine compounds, was measured in a pooled sample of breast milk from participants sampled in 2014-2016 as part of the WHO/UNEP breast milk monitoring program and compared to the POPs measured in pooled samples collected in 1987/1988 and 1992/1993, respectively. Therefore, this paper demonstrates the effectiveness of the Stockholm Convention on POPs by comparing the Austrian results from the WHO/UNEP global breast milk study from 1987 to 2016. However, the data also show that, despite these reductions, health-relevant levels are still being reached, particularly in terms of children's health when the presence of the new generation of POPs, such as PBDEs and PFAS, in human breast milk is taken into account.

Perfluorooctanesulfonic acid (PFOS) disrupts cadherin-16 in the developing rat thyroid gland

Perfluorooctanesulfonic acid (PFOS) can disrupt the thyroid hormone (TH) system in rodents, potentially affecting perinatal growth and neurodevelopment. Some studies also suggest that gestational exposure to PFOS can lead to lower TH levels throughout life, indicating that PFOS may compromise thyroid gland development. To address this question, we utilized a rat thyroid gland ex vivo culture system to study direct effects of PFOS on the developing thyroid. No significant changes to follicular structure or size were observed with 1 µM or 10 µM PFOS exposure. However, the transcription factor Foxe1, together with Tpo and Lrp2, were upregulated, whereas the key transcription factor Pax8 and its downstream target gene Cdh16 were significantly downregulated at the transcript level, observed with both RT-qPCR and RNAscope. Notably, Cdh16 expression was not uniformly downregulated across Cdh16-postive cells, but instead displayed a patchy expression pattern across the thyroid gland. This is a significant change in expression pattern compared to control thyroids where Cdh16 is expressed relatively uniformly. The disrupted expression pattern was also seen at the protein level. This suggests that PFOS exposure can impact follicular growth and structure. Compromised follicle integrity, if irreversible, could help explain reduced TH synthesis postnatally. This view is supported by observed changes to Tpo and Lrp2 expression, two factors that play a role in TH synthesis.

Closing the Organofluorine Mass Balance in Marine Mammals Using Suspect Screening and Machine Learning-Based Quantification

High-resolution mass spectrometry (HRMS)-based suspect and nontarget screening has identified a growing number of novel per- and polyfluoroalkyl substances (PFASs) in the environment. However, without analytical standards, the fraction of overall PFAS exposure accounted for by these suspects remains ambiguous. Fortunately, recent developments in ionization efficiency (IE) prediction using machine learning offer the possibility to quantify suspects lacking analytical standards. In the present work, a gradient boosted tree-based model for predicting log IE in negative mode was trained and then validated using 33 PFAS standards. The root-mean-square errors were 0.79 (for the entire test set) and 0.29 (for the 7 PFASs in the test set) log IE units. Thereafter, the model was applied to samples of liver from pilot whales (n = 5; East Greenland) and white beaked dolphins (n = 5, West Greenland; n = 3, Sweden) which contained a significant fraction (up to 70%) of unidentified organofluorine and 35 unquantified suspect PFASs (confidence level 2-4). IE-based quantification reduced the fraction of unidentified extractable organofluorine to 0-27%, demonstrating the utility of the method for closing the fluorine mass balance in the absence of analytical standards.

Prenatal exposure to per- and polyfluoroalkyl substances and DNA methylation in the placenta: A prospective cohort study

Epidemiological studies regarding the relationship between per- and polyfluoroalkyl substances (PFAS) and DNA methylation were limited. We investigated the associations of maternal PFAS concentrations with placental DNA methylation and examined the mediating role of methylation changes between PFAS and infant development. We measured the concentrations of 11 PFAS in maternal plasma during early pregnancy and infant development at six months of age. We analyzed genome-wide DNA methylation in 16 placental samples using reduced representation bisulfite sequencing. Additionally, we measured DNA methylation levels using bisulfite amplicon sequencing in 345 mother-infant pairs for five candidate genes, including carbohydrate sulfotransferase 7 (CHST7), fibroblast growth factor 13 (FGF13), insulin receptor substrate 4 (IRS4), paired like homeobox 2Ap (PHOX2A), and plexin domain containing 1 (PLXDC1). We found that placental DNA methylation profiles related to PFOA mainly enriched in angiogenesis and neuronal signaling pathways. PFOA was associated with hypomethylation of IRS4 and PLXDC1, and PFNA was associated with PLXDC1 hypomethylation. There were positive associations of CHST7 methylation with PFTrDA and IRS4 methylation with PFDoA and PFTrDA. PLXDC1 hypomethylation mediated the association between PFOA and suspected developmental delay in infants. Future studies with larger sample sizes are warranted to confirm these findings.

Estimation of per- and polyfluoroalkyl substances (PFAS) half-lives in human studies: a systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) constitute a heterogeneous group of synthetic compounds widely used in industrial applications. The estimation of PFAS half-life (t1/2) is essential to quantify their persistence, their toxicity and mechanism of action in humans.

OBJECTIVES

The purpose of this review is to summarize the evidence on PFAS half-lives in humans from the available literature, and to investigate the limitations and uncertainties characterizing half-life estimation.

METHODS

The search was conducted on PubMed, Scopus, and Embase databases up to July 03, 2023 and was aimed at identifying all papers that estimated PFAS half-life in human populations. We excluded studies on temporal trends or providing estimates of half-life based solely on renal clearance. As persistent and ongoing exposures can influence half-life estimation, we decided to include only studies that were conducted after the main source of exposure to PFAS had ceased. A random-effects meta-analysis was conducted on studies that reported perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) or perfluorohexanesulfonic acid (PFHxS) half-life estimation. Risk of bias was evaluated using the OHAT tool.

RESULTS

A total of 13 articles were included in the review, with 5 studies conducted in exposed general populations and 8 studies conducted in exposed workers; the estimated mean half-life ranged from 1.48 to 5.1 years for PFOA, from 3.4 to 5.7 years for total PFOS, and from 2.84 to 8.5 years for PFHxS. High heterogeneity among studies was observed; potential reasons include the variability among the investigated populations, discrepancies in considering ongoing exposures, variability in PFAS isomeric compositions, accounting for background exposure, time since exposure stopped and methods used for half-life estimation.

DISCUSSION

Despite the efforts made to better understand PFAS toxicokinetics, further studies are needed to identify important characteristics of these persistent chemicals. Biomonitoring studies should focus on persistent and unaccounted sources of exposure to PFAS and on individual characteristics potentially determining half-life, to ensure accurate estimates.

Endocrine Disruptors and Thyroid Health

A wide variety of thyroidal endocrine-disrupting chemicals (EDCs) have been identified. Exposure to known thyroidal EDCs is ubiquitous, and many likely remain unidentified. The sources of exposure include contaminated drinking water, air pollution, pesticides and agricultural chemicals, flame retardants, cleaning supplies, personal care products, food additives and packaging materials, coatings and solvents, and medical products and equipment. EDCs can affect thyroid hormone synthesis, transport, metabolism, and action in a myriad of ways. Understanding the health effects of thyroidal EDCs has been challenging because individuals may have multiple concomitant EDC exposures and many potential EDCs are not yet well characterized. Because of the importance of thyroid hormone for brain development in early life, pregnant women and young infants are particularly vulnerable to the effects of environmental thyroid disruption. The thyroidal effects of some EDCs may be exacerbated in iodine-deficient individuals, those with thyroid autoimmunity, and those with mutations in deiodinase genes. Differential exposures to EDCs may exacerbate health disparities in disadvantaged groups. High-throughput in vitro assays and in silico methods and methods that can detect the effects of relevant EDC mixtures are needed. In addition, optimal methods for detecting the effects of thyroidal EDCs on neurodevelopment need to be developed. Common sense precautions can reduce some thyroidal EDC exposures; however, regulation of manufacturing and drinking water content will ultimately be needed to protect populations.

Factors affecting the occurrence and accumulation of perfluoroalkyl acids in indoor dust in Tainan, Taiwan

Perfluoroalkyl acids (PFAAs) are environmentally and biologically persistent chemicals. In this study, we investigated the concentrations of six PFAAs in dust samples collected from different indoor environments in a college campus in Tainan, Taiwan, and assessed the health risk of PFAAs exposure to college students. We also analyzed the effects of dust characteristics (total organic carbon, moisture content, and dust content) on PFAAs levels. With regard to the space type, the median of total PFAAs concentrations were in the order of laboratories (528.9 μg kg-1) > offices (304.2 μg kg-1) > dormitories (180.1 μg kg-1) > classrooms (105.1 μg kg-1). With regard to the height from the ground, the median total PFAAs concentrations were in the order of dust near the floors (>2 m; 383.6 μg kg-1) > near the ceiling (0-2 m; 202.5 μg kg-1) > on the ground (0 m; 145.6 μg kg-1). The main species of PFAAs, perfluorooctane sulfonate and short-chain perfluoroalkyl carboxylates, accounted for respectively 30%-60% and ∼20%-37% of total PFAAs pollution in the indoor space types and sampling heights under consideration. The average daily intake (ADI) values of six PFAAs for college students were found to be 0.059-0.126 ng kg-1 BW day-1 (BW: body weight), with dormitories and workplaces (i.e., laboratories and offices) accounting for over 40% and ∼50% of the ADI, respectively. The estimated hazard quotient ranged from 0.0029 to 0.0063, three orders of magnitude lower than 1, suggesting relatively low risks for college students exposed to the six PFAAs monitored in indoor dust. The analysis of dust characteristics revealed that total organic carbon did not have a significant effect on PFAAs levels as we expected. In contrast, dust moisture and cation content dominated PFAAs accumulation.

Removal of Per- and Polyfluoroalkyl substances by anion exchange resins: Scale-up of rapid small-scale column test data

Anion exchange (IX) is a readily implementable water treatment method that can effectively remove per- and polyfluoroalkyl substances (PFAS). The overarching objective of this research was to predict PFAS removal in full- or pilot-scale packed-bed IX resin contactors from rapid small-scale column test (RSSCT) data. Specific objectives were to (1) assess the effects of IX resin crushing on total anion exchange capacity and packed bed density, (2) determine the effects of initial PFAS concentration on PFAS uptake capacity, (3) determine the rate-limiting step controlling PFAS uptake kinetics, (4) determine the effects of hydraulic loading rate on PFAS uptake capacity, and (5) link constant diffusivity RSSCT data to pilot test data to develop a scale-up protocol. Experiments were conducted with two single-use IX resins and three water matrices, including coagulated surface water and groundwater. Crushing IX resin did not substantially change the bed density and total anion exchange capacity, but the morphology of particles changed from almost perfectly spherical to irregularly shaped. PFAS uptake capacity was independent of influent PFAS concentrations in the 30-300 ng/L range. This finding facilitated the development of an RSSCT scale-up approach because influent PFAS concentrations in RSSCTs and corresponding pilot tests often differ. Biot number values and data from interrupted RSSCTs demonstrated that film diffusion or a combination of film diffusion and intraparticle diffusion controls the rate of PFAS uptake by IX resins. From RSSCTs with identical empty bed contact times but different hydraulic loading rates (vf), PFAS uptake capacity was found to be a function of the square root of the product of Sherwood number and particle shape factor (Sh×ϕ). Using a constant diffusivity RSSCT design with a reduced vf, full- or pilot-scale PFAS breakthrough data can therefore be predicted by multiplying the bed volumes of water treated in the RSSCT by a factor of (Shpilot×ϕpilot)/(ShRSSCT×ϕRSSCT) . This research will support the design of future IX treatment processes in the context of PFAS remediation and drinking water treatment.

Effects of perfluorooctanoic acid and perfluorooctane sulfonic acid on microbial community structure during anaerobic digestion

Per- and polyfluoroalkyl substances (PFASs) are recalcitrant organic pollutants, which accumulate widely in aquatic and solid matrices. Anaerobic digestion (AD) is one of possible options to manage organic wastes containing PFASs, however, the impacts of different types of PFAS on AD remains unclear. This study aimed to critically investigate the effects of two representative PFAS compounds, i.e., perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), on the AD performance and microbial community structure. 100 mg/L of both PFOA and PFOS considerably inhibited the AD performance and changed the microbial community structure. Especially, PFOA was more toxic to bacterial and archaeal activity than PFOS, which was reflected in AD performance. In addition, the sulfonic acid group in PFOS affected the changes in microbial community structure by inducing abundant sulfate reducing bacteria (i.e., Desulfobacterota). This study provides a significant reference to the response of AD system on different PFAS types and dosage.

Surface modifications of biopolymers for removal of per- and polyfluoroalkyl substances from water: Current research and perspectives

Per- and polyfluoroalkyl substances (PFAS) are highly recalcitrant organic contaminants that have attracted ever-increasing attention from the general public, government agencies and scientific communities. To remove PFAS from water, especially the enormous volume of drinking water, stormwater, and groundwater, sorption is the most practical approach. Success of this approach demands green, renewable, and sustainable materials for capturing PFAS at ng/L or µg/L levels. To meet this demand, this manuscript critically reviewed sorbents developed from biopolymers, such as chitosan (CTN), alginate (ALG), and cellulose (CEL) covering the period from 2008 to 2023. The use of different cross-linkers for the surface modifications of biopolymers were described. The underlying removal mechanism of biosorbents for PFAS adsorption from molecular perspectives was discussed. Besides reviewing and comparing the performance of different bio-based sorbents with respect to environmental factors like pH, and sorption kinetics and capacity, strategies for modifying biosorbents for better performance were proposed. Additionally, approaches for regeneration and reuse of the biosorbents were discussed. This was followed by further discussion of challenges facing the development of biosorbents for PFAS removal.

Distinct bile acid alterations in response to a single administration of PFOA and PFDA in mice

Per- and polyfluoroalkyl substances (PFASs), a group of synthetic chemicals that were once widely used for industrial purposes and in consumer products, are widely found in the environment and in human blood due to their extraordinary resistance to degradation. Once inside the body, PFASs can activate nuclear receptors such as PPARα and CAR. The present study aimed to investigate the impact of perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA) on liver structure and functions, as well as bile acid homeostasis in mice. A single administration of 0.1 mmole/kg of PFDA, not PFOA, elevated serum ALT and bilirubin levels and caused cholestasis in WT mice. PFDA increased total and various bile acid species in serum but decreased them in the liver. Furthermore, in mouse livers, PFDA, not PFOA, down-regulated mRNA expression of uptake transporters (Ntcp, Oatp1a1, 1a4, 1b2, and 2b1) but induced efflux transporters (Bcrp, Mdr2, and Mrp2-4). In addition, PFDA, not PFOA, decreased Cyp7a1, 7b1, 8b1, and 27a1 mRNA expression in mouse livers with concomitant hepatic accumulation of cholesterol. In contrast, in PPARα-null mice, PFDA did not increase serum ALT, bilirubin, or total bile acids, but produced prominent hepatosteatosis; and the observed PFDA-induced expression changes of transporters and Cyps in WT mice were largely attenuated or abolished. In CAR-null mice, the observed PFDA-induced bile acid alterations in WT mice were mostly sustained. These results indicate that, at the dose employed, PFDA has more negative effects than PFOA on liver function. PPARα appears to play a major role in mediating most of PFDA-induced effects, which were absent or attenuated in PPARα-null mice. Lack of PPARα, however, exacerbated hepatic steatosis. Our findings indicate separated roles of PPARα in mediating the adaptive responses to PFDA: protective against hepatosteatosis but exacerbating cholestasis.

Determinants of PFOA Serum Half-Life after End of Exposure: A Longitudinal Study on Highly Exposed Subjects in the Veneto Region

BACKGROUND

Perfluoroalkyl substances (PFAS) are widely used, ubiquitous, and highly persistent man-made chemicals. Groundwater of a vast area of the Veneto Region (northeastern Italy) was found to be contaminated by PFAS from a manufacturing plant active since the late 1960s. As a result, residents were overexposed to PFAS through drinking water until 2013, mainly to perfluorooctanoic acid (PFOA).

OBJECTIVES

The aim of the present study was to estimate the rates of decline in serum PFOA and their corresponding serum half-lives, while characterizing their determinants.

METHODS

We investigated 5,860 subjects more than 14 years of age who enrolled in the second surveillance round of the regional health surveillance program. Two blood samples were collected between 2017 and 2022 (average time between measurements: 4 years). Serum PFOA excretion rates and half-lives were estimated based on linear mixed effect models, modeling subject-specific serum PFOA concentrations over time and correcting for background concentrations. For modeling determinants of half-life [age, sex, body mass index (BMI), smoking-habit, alcohol consumption, and estimated glomerular filtration rate (eGFR)], we added interaction terms between each covariate and the elapsed time between measurements. Perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) apparent half-lives were also estimated. A separate analysis was conducted in children (n = 480 ). All analyses were stratified by sex.

RESULTS

Median initial serum concentrations of PFOA was 49  ng / mL (range: 0.5-1,090), with a median reduction of 62.45%. The mean estimated PFOA half-life was 2.36 years [95% confidence interval (CI): 2.33, 2.40], shorter in women (2.04; 95% CI: 2.00, 2.08) compared to men (2.83; 95% CI: 2.78, 2.89). Half-lives varied when stratified by some contributing factors, with faster excretion rates in nonsmokers and nonalcohol drinkers (especially in males).

CONCLUSIONS

This study, to our knowledge the largest on PFOA half-life, provides precise estimates in young adults whose exposure via drinking water has largely ceased. For other PFAS, longer half-lives than reported in other studies can be explained by some ongoing exposure to PFAS via other routes. https://doi.org/10.1289/EHP13152.

PFAS: exploration of neurotoxicity and environmental impact

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants stemming from various industrial and consumer products, posing a grave threat to both human health and ecosystems. PFAS contamination arises from multiple sources, including industrial effluents, packaging, and product manufacturing, accumulating in plants and impacting the food chain. Elevated PFAS levels in water bodies pose significant risks to human consumption. This review focuses on PFAS-induced neurological effects, highlighting disrupted dopamine signalling and structural neuron changes in humans. Animal studies reveal apoptosis and hippocampus dysfunction, resulting in memory loss and spatial learning issues. The review introduces the BKMR model, a machine learning technique, to decipher intricate PFAS-neurotoxicity relationships. Epidemiological data underscores the vulnerability of young brains to PFAS exposure, necessitating further research. Stricter regulations, industry monitoring, and responsible waste management are crucial steps to reduce PFAS exposure.

Assessing the performance of a targeted absolute quantification isotope dilution liquid chromatograhy tandem mass spectrometry assay versus a commercial nontargeted relative quantification assay for detection of three major perfluoroalkyls in human blood

Isotope dilution ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) is commonly used for trace analysis of polyfluoroalkyl and perfluoroalkyl substances (PFAS) in difficult matrices. Commercial nontargeted analysis of major PFAS where relative concentrations are obtained cost effectively is rapidly emerging and is claimed to provide comparable results to that of absolute quantification using matrix matched calibration and isotope dilution UHPLC-MS/MS. However, this remains to be demonstrated on a large scale. We aimed to assess the performance of a targeted absolute quantification isotope dilution LC-MS/MS assay versus a commercial nontargeted relative quantification assay for detection of three major PFAS in human blood. We evaluated a population-based cohort of 503 individuals. Correlations were assessed using Spearman's rank correlation coefficients (rho). Precision and bias were assessed using Bland-Altman plots. For perfluorooctane sulfonic acid, the median concentrations were 5.10 ng/mL (interquartile range [IQR] 3.50-7.24 ng/mL), the two assays correlated with rho 0.83. For perfluorooctanoic acid, the median concentrations were 2.14 ng/mL (IQR 1.60-3.0 ng/mL), the two assays correlated with rho 0.92. For perfluorohexanesulfonate, the median concentrations were 5.5 ng/mL (IQR 2.50-11.61 ng/mL), the two assays correlated with rho 0.96. The Bland-Altman statistical test showed agreement of the mean difference for the majority of samples (97-98%) between the two assays. Absolute plasma concentrations of PFAS obtained using matrix matched calibration and isotope dilution UHPLC-MS/MS show agreement with relative plasma concentrations from a nontargeted commercial platform by Metabolon. We observed striking consistency between the two assays when examining the associations of the three PFAS with cholesterol, offering additional confidence in the validity of utilizing the nontargeted approach for correlations with various health phenotypes.

A targeted and non-targeted discovery screening approach for poly-and per-fluoroalkyl substances in model environmental biota samples

A comprehensive analytical approach for targeted and non-targeted discovery screening of per- and polyfluoroalkyl substances (PFAS) was developed and applied to model complex environmental biotic samples. Samples were extracted by formic acid-acetonitrile solution and cleaned up and fractionated by SPE (WAX). Target PFAS quantification was performed by ultra-high performance liquid chromatography interfaced with a triple quadrupole mass spectrometer (UPLC-QqQ-MS/MS). Non-targeted analysis (NTA) PFAS screening was performed with UPLC coupled with a quadrupole-Exactive orbitrap high resolution mass spectrometer (UPLC-Q-Exactive-HRMS). An iterative exclusion (IE) approach was applied to data acquisition for NTA suspect screening to increase the potential for unknown PFAS discovery with MS/MS. A complex workflow in Compound Discoverer was set up to automate data processing of the PFAS suspects search. New mass lists and MS/MS databases, which included a large number of PFAS, were set up and introduced into the search for high-throughput structure identification using HRMS techniques. The integrated targeted-NTA method successfully analyzed for legacy and alternative PFAS in model environmental biota samples, namely polar bear liver and bird egg samples. Targeted analysis provided unequivocal identification of well known/established PFAS (mainly perfluoroalkyl acids) with quantification at very low levels. The NTA suspect screening was able to determine a broader range of PFAS. The data analysis method offered high-confidence annotations for PFAS despite lacking available authentic standards. Overall, the analytical coverage of PFAS was greater and elucidated other PFAS present in these model apex predators.

Identification and quantification of fluorinated polymers in consumer products by combustion ion chromatography and pyrolysis-gas chromatography-mass spectrometry

Total fluorine was determined in 45 consumer product samples from the Swedish market which were either suspected or known to contain fluorinated polymers. Product categories included cookware (70-550 000 ppm F), textiles (10-1600 ppm F), electronics (20-2100 ppm F), and personal care products (10-630 000 ppm F). To confirm that the fluorine was organic in nature, and deduce structure, a qualitative pyrolysis-gas chromatography-mass spectrometry (pyr-GC/MS) method was validated using a suite of reference materials. When applied to samples with unknown PFAS content, the method was successful at identifying polytetrafluoroethylene (PTFE) in cookware, dental products, and electronics at concentrations as low as 0.1-0.2 wt%. It was also possible to distinguish between 3 different side-chain fluorinated polymers in textiles. Several products appeared to contain high levels of inorganic fluorine. This is one of the few studies to quantify fluorine in a wide range of consumer plastics and provides important data on the concentration of fluorine in materials which may be intended for recycling, along with insights into the application of pyr-GC/MS for structural elucidation of fluorinated polymers in consumer products.

Binding of Per- and Polyfluoroalkyl Substances (PFAS) to Serum Proteins: Implications for Toxicokinetics in Humans

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of highly persistent anthropogenic chemicals that are detectable in the serum of most humans. PFAS exposure has been associated with many adverse effects on human health including immunotoxicity, increased risk of certain cancers, and metabolic disruption. PFAS binding to the most abundant blood serum proteins (human serum albumin [HSA] and globulins) is thought to affect transport to active sites, toxicity, and elimination half-lives. However, few studies have investigated the competitive binding of PFAS to these proteins in human serum. Here, we use C18 solid-phase microextraction fibers to measure HSA-water and globulin-water distribution coefficients (DHSA/w, Dglob/w) for PFAS with carbon chains containing 4 to 13 perfluorinated carbons (ηpfc = 4-13) and several functional head-groups. PFAS with ηpfc < 7 were highly bound to HSA relative to globulins, whereas PFAS with ηpfc ≥ 7 showed a greater propensity for binding to globulins. Experimentally measured DHSA/w and Dglob/w and concentrations of serum proteins successfully predicted the variability in PFAS binding in human serum. We estimated that the unbound fraction of serum PFAS varied by up to a factor of 2.5 among individuals participating in the 2017-2018 U.S. National Health and Nutrition Examination Survey. These results suggest that serum HSA and globulins are important covariates for epidemiological studies aimed at understanding the effects of PFAS exposure.

Fluoroether Double-Chain Phosphate Surfactants: An Exploration of Alternatives to Fluorotelomer Surfactants

While legacy fluorosurfactants have already been categorized as persistent organic pollutants, there appeared to be many strategies to develop alternatives. In this work, fluoroether double-chain phosphate surfactants (C72 diPAP-Na and C72 diPAP-NH4) were designed and synthesized with the initial intention of exploring the creation of new fluorosurfactants containing oxygen heteroatoms in the fluorocarbon chain segments to provide an alternative to the legacy long-chain fluorosurfactants. Furthermore, it was expected that they would even exceed the existing 6:2 fluorotelomer surfactants (6:2 diPAP-Na and 6:2 diPAP-NH4). Compared with characterizations of surface activity, foam performance, and wettability, the results showed that each of them has its own distinctive performance. Although the C72 series as new fluoroether surfactants cannot fully replace the 6:2 series of fluorosurfactants in terms of performance, there is a possibility of substitution in some aspects, which is of positive significance for further exploration to improve alternatives to legacy fluorosurfactants.

Distribution, sources and ecological risks of per- and polyfluoroalkyl substances in overlying water and sediment from the mangrove ecosystem in Hainan Island, China

Since data on Per- and polyfluoroalkyl substances (PFASs) in mangrove ecosystems are very limited. This study investigated the occurrence, distribution, sources, and ecological risk of 24 PFASs in the overlying waters and sediments of mangrove systems in Hainan Island, China. The concentration levels of PFASs in water and sediment ranged from 6.3 to 35.3 ng/L and from 0.33 to 10.2 ng/g dw, respectively. In terms of spatial distribution, firstly, the mangrove forests in Haikou and Sanya contained higher levels of PFASs; secondly, the eastern region contained higher levels of PFASs than the western region. The reasons for this may be related to the population size and development level of the region. For the organic carbon normalized sediment-water partition coefficient (log Koc), the results showed that log Koc decreased with increasing carbon chains for short-chain PFASs (with ≤6 CF2 units) and increased with increasing carbon chains for long-chain PFASs (with ˃6 CF2 units). Principal Component Analysis (PCA) and correlation analysis were employed to pinpoint specific origins of PFASs, namely firefighting, metal plating, food packaging, textiles, and fluoropolymer manufacturing. The risk quotient (RQ) values of PFASs in mangrove ecosystems on Hainan Island were all <1, but the existence of potential risks cannot be excluded. Hence, further investigations related to the bioaccumulation effects of PFASs in organisms in mangrove forests should be conducted to gain a more comprehensive understanding of their environmental behavior.

Hepatic concentrations of per- and polyfluoroalkyl substances (PFAS) in dolphins from south-east Australia: Highest reported globally

Per- and polyfluoroalkyl substances (PFAS) concentrations were investigated in hepatic tissue of four dolphin species stranded along the south-east coast of Australia between 2006 and 2021; Burrunan dolphin (Tursiops australis), common bottlenose dolphin (Tursiops truncatus), Indo-Pacific bottlenose dolphin (Tursiops aduncus), and short-beaked common dolphin (Delphinus delphis). Two Burrunan dolphin populations represented in the dataset have the highest reported global population concentrations of ∑25PFAS (Port Phillip Bay median 9750 ng/g ww, n = 3, and Gippsland Lakes median 3560 ng/g ww, n = 8), which were 50-100 times higher than the other species reported here; common bottlenose dolphin (50 ng/g ww, n = 9), Indo-Pacific bottlenose dolphin (80 ng/g ww, n = 1), and short-beaked common dolphin (61 ng/g ww, n = 12). Also included in the results is the highest reported individual ∑25PFAS (19,500 ng/g ww) and PFOS (18,700 ng/g ww) concentrations, at almost 30 % higher than any other Cetacea reported globally. Perfluorooctane sulfonate (PFOS) was above method reporting limits for all samples (range; 5.3-18,700 ng/g ww), and constituted the highest contribution to overall ∑PFAS burdens with between 47 % and 99 % of the profile across the dataset. The concentrations of PFOS exceed published tentative critical concentrations (677-775 ng/g) in 42 % of all dolphins and 90 % of the critically endangered Burrunan dolphin. This research reports for the first time novel and emerging PFASs such as 6:2 Cl-PFESA, PFMPA, PFEECH and FBSA in marine mammals of the southern hemisphere, with high detection rates across the dataset. It is the first study to show the occurrence of PFAS in the tissues of multiple species of Cetacea from the Australasian region, demonstrating high global concentrations for inshore dolphins. Finally, it provides key baseline knowledge to the potential exposure and bioaccumulation of PFAS compounds within the coastal environment of south-east Australia.

Prenatal per- and polyfluoroalkyl substances exposure and gut microbiota of infants: A prospective cohort study

Prenatal exposure to per- and polyfluoroalkyl substances (PFASs) has been reported to be linked to a series of adverse health outcomes in mothers and their children. As the gut microbiota is a sensitive biomarker for assessing the toxicity of environmental contaminants, this study attempted to investigate whether prenatal PFASs exposure was associated with the gut microbiota of infants. Based on the Shanghai-Minhang Birth Cohort Study, this prospective cohort study included 69 mother-infant pairs. Fasting blood samples were collected from pregnant women for the PFASs assay. We collected fecal samples of infants at 1 year of age and analyzed the V3-V4 hypervariable region of the bacterial 16 S rRNA gene by high-throughput sequencing. Among the detected 11 PFASs, the concentration of perfluorooctanoic acid (22.19 ng/mL) was the highest, followed by perfluorooctane sulfonic acid (12.08 ng/mL). Compared with infants whose mothers' total PFASs concentrations during pregnancy were at the 40th percentile or lower (reference group), the species richness and diversity of microbiota were lower in infants prenatally exposed to a high level of PFASs (the sum of PFASs concentrations above the 60th percentile). Prenatal exposure to PFASs was associated with a higher proportion of Acidaminococcaceae, Acidaminococcus, Megamonas, Megasphaera micronuciformis and Megamonas funiformis in infants. The changes of the species have been suggested to be associated with immune and metabolic dysfunction in humans. Functional alterations of gut microbiota due to PFASs exposure were dominated by an enrichment of butanoate metabolism. Our preliminary findings may shed light on the potential role of the microbiota underlying the well-known impact of prenatal PFASs exposure on health outcomes of humans in later life.

Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is persistent endocrine disrupting chemicals. Previous evidence suggests that exposure to PFAS is associated with reproductive hormone levels, but the results of relevant studies are inconsistent. The objective of our study is to determine the association between exposure to PFAS and reproductive hormone levels in gender-specific general population.

METHOD

Based on scientific search strategies, we systematically searched PubMed, Web of Science, Embase, Medline, and Scopus to obtain the eligible studies published before January 21, 2023. The quality of the included articles was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool. We combined the β coefficient and 95% confidence intervals (CI) using Stata.17 with random-effect model or fixed-effect model. We also performed subgroup analysis, sensitivity analysis, and Begger's and Egger's tests.

RESULTS

Eleven studies involving 7714 participants were included. Meta-analysis showed that PFHxS exposure was positively associated with estradiol (E2) levels in female [β = 0.030, 95% CI: (0.013, 0.046), P = 0.000]. A negative association was found between PFOA [β = -0.012, 95% CI: (-0.023, -0.002), P = 0.017] and PFOS [β = -0.011; 95% CI: (-0.021, -0.000), P = 0.042] exposure with male testosterone (TT) levels. In the subgroup analysis, there were stronger associations in children than in adults. And the high heterogeneity was mainly due to the cross-sectional studies. Publication bias was not found in most of the analyses.

CONCLUSION

Our study showed that PFAS exposure was significantly associated with reproductive hormone levels. Further related studies are needed to identify the association and potential mechanism in the future.

PFHxS Exposure and the Risk of Non-Alcoholic Fatty Liver Disease

Perfluorohexanesulfonic acid (PFHxS) is a highly prevalent environmental pollutant, often considered to be less toxic than other poly- and perfluoroalkyl substances (PFASs). Despite its relatively lower environmental impact compared to other PFASs, several studies have suggested that exposure to PFHxS may be associated with disruptions of liver function in humans. Nevertheless, the precise pathomechanisms underlying PFHxS-induced non-alcoholic fatty liver disease (NAFLD) remain relatively unclear. Therefore, this study applied our previously published transcriptome dataset to explore the effects of PFHxS exposure on the susceptibility to NAFLD and to identify potential mechanisms responsible for PFHxS-induced NAFLD through transcriptomic analysis conducted on zebrafish embryos. Results showed that exposure to PFHxS markedly aggravated hepatic symptoms resembling NAFLD and other metabolic syndromes (MetS) in fish. Transcriptomic analysis unveiled 17 genes consistently observed in both NAFLD and insulin resistance (IR), along with an additional 28 genes identified in both the adipocytokine signaling pathway and IR. These shared genes were also found within the NAFLD dataset, suggesting that hepatic IR may play a prominent role in the development of PFHxS-induced NAFLD. In conclusion, our study suggests that environmental exposure to PFHxS could be a potential risk factor for the development of NAFLD, challenging the earlier notion of PFHxS being safer as previously claimed.

Combination of separation and degradation methods after PFAS soil washing

The current study evaluated a three-stage treatment to remediate PFAS-contaminated soil. The treatment consisted of soil washing, foam fractionation (FF), and electrochemical oxidation (EO). The possibility of replacing the third stage, i.e., EO, with an adsorption process was also assessed. The contamination in the studied soils was dominated by perfluorooctane sulfonate (PFOS), with a concentration of 760 and 19 μg kg-1 in soil I and in soil II, accounting for 97 % and 70 % of all detected per-and polyfluoroalkyl substances (PFAS). Before applying a pilot treatment of soil, soil washing was performed on a laboratory scale, to evaluate the effect of soil particle size, initial pH and a liquid-to-soil ratio (L/S) on the leachability of PFAS. A pilot washing system generated soil leachate that was subsequently treated using FF and EO (or adsorption) and then reused for soil washing. The results indicated that the leaching of PFAS occurred easier in 0.063-1 mm particles than in the soil particles having a size below 0.063 mm. Both alkaline conditions and a continual replacement of the leaching solution increased the leachability of PFAS. The analysis using one-way ANOVA showed no statistical difference in means of PFOS washed out in laboratory and pilot scales. This allowed estimating twenty washing cycles using 120 L water to reach 95 % PFOS removal in 60 kg soil. The aeration process removed 95-99 % PFOS in every washing cycle. The EO and adsorption processes achieved similar results removing up to 97 % PFOS in concentrated soil leachate. The current study demonstrated a multi-stage treatment as an effective and cost-efficient method to permanently clean up PFAS-contaminated soil.

Toxicity Assessment of Mixed Exposure of Nine Perfluoroalkyl Substances at Concentrations Relevant to Daily Intake

Per- and poly-fluoroalkyl substances (PFAS) exhibit high persistence in the environment and accumulate within the human body, warranting a thorough assessment of their toxicity. In this study, we exposed mice (male C57BL/6J mice aged 8 weeks) to a composite of nine PFAS, encompassing both long-chain PFAS (e.g., perfluorooctanoic acid and perfluorooctanesulfonic acid) and short-chain PFAS (e.g., perfluorobutanoic acid and perfluorobutanesulfonic acid). The exposure concentrations of PFAS were equivalent to the estimated daily human intake in the composition reported (1 µg/L (sum of the nine compounds), representing the maximum reported exposure concentration). Histological examination revealed hepatocyte vacuolization and irregular hepatocyte cord arrangement, indicating that exposure to low levels of the PFAS mixture causes morphological changes in liver tissues. Transcriptome analysis revealed that PFAS exposure mainly altered a group of genes related to metabolism and chemical carcinogenesis. Machine learning analysis of the liver metabolome showed a typical concentration-independent alteration upon PFAS exposure, with the annotation of substances such as glutathione and 5-aminovaleric acid. This study demonstrates that daily exposure to PFAS leads to morphological changes in liver tissues and alters the expression of metabolism- and cancer-related genes as well as phospholipid metabolism.

Altered Transcriptome Response in PBMCs of Czech Adults Linked to Multiple PFAS Exposure: B Cell Development as a Target of PFAS Immunotoxicity

While the immunomodulation effects of per- and polyfluoroalkyl substances (PFASs) are described on the level of clinical signs in epidemiological studies (e.g., suppressed antibody response after vaccination), the underlying mechanism has still not been fully elucidated. To reveal mechanisms of PFAS exposure on immunity, we investigated the genome-wide transcriptomic changes of peripheral blood mononuclear cells (PBMCs) responding to PFAS exposure (specifically, exposure to PFPA, PFOA, PFNA, PFDA, PFUnDA, PFHxS, and PFOS). Blood samples and the chemical load in the blood were analyzed under the cross-sectional CELSPAC: Young Adults study. The overall aim of the study was to identify sensitive gene sets and cellular pathways conserved for multiple PFAS chemicals. Transcriptome networks related to adaptive immunity were perturbed by multiple PFAS exposure (i.e., blood levels of at least four PFASs). Specifically, processes tightly connected with late B cell development, such as B cell receptor signaling, germinal center reactions, and plasma cell development, were shown to be affected. Our comprehensive transcriptome analysis identified the disruption of B cell development, specifically the impact on the maturation of antibody-secreting cells, as a potential mechanism underlying PFAS immunotoxicity.

Occurrence of Major Perfluorinated Alkylate Substances in Human Blood and Target Organs

Human exposure to perfluorinated alkylate substances (PFASs) is usually assessed from the concentrations in serum or plasma, assuming one-compartment toxicokinetics. To characterize body distributions of major PFASs, we obtained and extracted tissue samples from 19 forensic autopsies of healthy adult subjects who had died suddenly and were not known to have elevated levels of PFAS exposure. As target organs of toxicological importance, we selected the liver, kidneys, lungs, spleen, and brain, as well as whole blood. Samples weighing about 0.1 g were analyzed by liquid chromatography coupled to triple mass spectrometers. Minor variations in PFAS concentrations were found between the kidney cortex and medulla and between lung lobes. Organ concentrations of perfluorooctanoic sulfonate (PFOS) and perfluorononanoate (PFNA) correlated well with blood concentrations, while perfluorooctanoate (PFOA) and perfluorohexanoic sulfonate (PFHxS) showed more variable associations. Likewise, the liver concentrations correlated well with those of other organs. Calculations of relative distributions were carried out to assess the interdependence of organ retentions. Equilibrium model predictions largely explained the observed PFAS distributions, except for the brain. Although the samples were small and affected by a possible lack of homogeneity, these findings support the use of blood-PFAS concentrations as a measure of PFAS exposure, with the liver possibly acting as the main organ of retention.

Validating blood microsampling for per- and polyfluoroalkyl substances quantification in whole blood

Microsampling allows the collection of blood samples using a method which is inexpensive, simple and minimally-invasive, without the need for specially-trained medical staff. Analysis of whole blood provides a more holistic understanding of per- and polyfluoroalkyl substances (PFAS) body burden. Capillary action microsamplers (Trajan hemaPEN®) allow the controlled collection of whole blood as dried blood spots (DBS) (four 2.74 µL ± 5 %). The quantification of 75 PFAS from DBS was evaluated by comparing five common extraction techniques. Spiked blood (5 ng/mL PFAS) was extracted by protein precipitation (centrifuged; filtered), acid-base liquid-liquid extraction, trypsin protease digestion, and weak anion exchange (WAX) solid-phase extraction with analysis by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Filtered protein precipitation was the most effective extraction method, recovering 72 of the 75 PFAS within 70 to 130 % with method reporting limit (MRL) for PFOS of 0.17 ng/L and ranging between 0.05 ng/mL and 0.34 ng/mL for all other PFAS. The optimised method was applied to human blood samples to examine Inter- (n = 7) and intra-day (n = 5) PFAS blood levels in one individual. Sixteen PFAS were detected with an overall Σ16PFAS mean = 6.3 (range = 5.7-7.0) ng/mL and perfluorooctane sulfonate (branched and linear isomers, ΣPFOS) = 3.3 (2.8-3.7) ng/mL being the dominant PFAS present. To the authors knowledge, this minimally invasive self-sampling protocol is the most extensive method for PFAS in blood reported and could be a useful tool for large scale human biomonitoring studies.

Aptamer-Magnetic Nanoparticle Complexes for Powerful Biosensing: A Comprehensive Review

The selective and sensitive diagnosis of diseases is a significant matter in the early stages of the cure of illnesses. To elaborate, although several types of probes have been broadly applied in clinics, magnetic nanomaterials-aptamers, as new-generation probes, are becoming more and more attractive. The presence of magnetic nanomaterials brings about quantification, purification, and quantitative analysis of biomedical, especially in complex samples. Elaborately, the superparamagnetic properties and numerous functionalized groups of magnetic nanomaterials are considered two main matters for providing separation ability and immobilization substrate, respectively. In addition, the selectivity and stability of aptamer can present a high potential recognition element. Importantly, the integration of aptamer and magnetic nanomaterials benefits can boost the performance of biosensors for biomedical analysis by introducing efficient and compact probes that need low patient samples and fast diagnosis, user-friendly application, and high repeatability in the quantification of biomolecules. The primary aim of this review is to suggest a summary of the effect of the employed other types of nanomaterials in the fabrication of novel aptasensors-based magnetic nanomaterials and to carefully explore various applications of these probes in the quantification of bioagents. Furthermore, the application of these versatile and high-potential probes in terms of the detection of cancer cells and biomarkers, proteins, drugs, bacteria, and nucleoside were discussed. Besides, research gaps and restrictions in the field of biomedical analysis by magnetic nanomaterials-aptamers will be discussed.

Sublethal perfluorooctanoic acid and perfluorooctanesulfonic acid delay C. elegans larval development and population growth but do not alter egg hatching

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are polyfluoroalkyl substances (PFAS) used as surface coatings in manufacturing. Exposure to PFAS was shown to be correlated with infertility, low birth weight, and delayed aspects of pubertal development in mammals. Despite many correlational studies, there have been few direct investigations examining the link between PFAS exposure and early animal development. The aim of this study was to (1) examine the effects of PFOA on development and reproduction using the roundworm Caenorhabditis elegans, a model with a high predictive value for human reproductive toxicity and (2) compare observations to exposure to PFOS. PFAS exposure did not markedly alter egg hatching but delayed population growth, in part due to slower larval development. PFAS-exposed worms took longer to progress through larval stages to reach reproductive maturity, and this was not attributed to PFOA-induced toxicity to their food. Our results provide a robust benchmark for testing developmental and reproductive toxicity for other PFAS and PFAS-alternatives which continue to be used in manufacturing and released into the environment.

Associations of exposure to per- and polyfluoroalkyl substances mixture with the numbers of lymph nodes in colorectal cancer patients

Colorectal cancer (CRC) is widely known with a high incidence rate worldwide, but the correlation between exposure to per- and polyfluoroalkyl substances (PFAS) and the number of lymph nodes in CRC patients remains unclear. In the present study, we enrolled 305 CRC patients (122 females and 183 males) at Beijing Hospital in China. A total of 17 PFAS were detected in serum samples of these patients, and 5 PFAS with detection rates >75% were selected in this study. The CRC patients' number of metastatic lymph nodes (MLNs) and total lymph nodes (TLNs) were chosen as outcomes. Poisson regression models were used to analyze the associations between single PFAS and number of MLNs and TLNs. Quantile g-Computation models were performed to examine the joint effect of PFAS mixtures on number of MLNs and TLNs. A positive correlation between serum PFAS levels and number of MLNs was identified. For instance, the numbers of MLNs in patients with serum PFOA, PFNA, 6:2 Cl-PFESA concentrations at the 95th percentile were 27% (95% CI: 1%, 60%), 35% (95% CI: 1%, 82%), 87% (95% CI: 4%, 238%) higher compared with the threshold level. The results of Quantile g-Computation models also showed that every quantile increase in PFAS mixtures was associated with a 4.67%, (95% CI: 0.07%, 9.48%) increase in the numbers of MLNs, and PFOS dominated the effects of the mixtures. Moreover, a negative correlation between PFAS mixtures and number of TLNs in patients with no MLNs was also observed. The present study suggested that exposure to PFAS may worsen the prognosis of CRC patients. These findings could help guide future research and public health policies aimed at reducing exposure to PFAS and mitigating their potential impacts on human health.