Estimated daily intake of per- and polyfluoroalkyl substances related to different particle size fractions of house dust

Perfluorooctanoic acid inhibits cell proliferation through mitochondrial damage

Grown evidence has shown that the liver and reproductive organs were the main target organs of perfluorooctanoic acid (PFOA). Herein, we studied a toxic mechanism of PFOA using HeLa Chang liver epithelial cells. When incubated with PFOA for 24 h or 48 h, cell proliferation was inhibited in a concentration- and time-dependent fashion, but interestingly, the feature of dead cells was not notable. Mitochondrial volume was increased with concentration and time, whereas the mitochondrial membrane potential and produced ATP amounts were significantly reduced. Autophagosome-like vacuoles and contraction of the mitochondrial inner membrane were observed in PFOA-treated cells. The expression of acetyl CoA carboxylase (ACC) and p-ACC proteins rapidly decreased, and that of mitochondrial dynamics-related proteins increased. The expression of solute carrier family 7 genes, ChaC glutathione-specific gamma-glutamylcyclotransferase 1, and 5S ribosomal RNA gene was up-regulated the most in cells exposed to PFOA for 24 h, and the KEGG pathway analysis revealed that PFOA the most affected metabolic pathways and olfactory transduction. More importantly, PPAR alpha, fatty acid binding protein 1, and CYP450 family 1 subfamily A member 1 were identified as the target proteins for binding between PFOA and cells. Taken together, we suggest that disruption of mitochondrial integrity and function may contribute closely to PFOA-induced cell proliferation inhibition.

Prediction of perfluoroalkyl acids (PFAAs) in homegrown eggs: Insights into abiotic and biotic factors affecting bioavailability and derivation of potential remediation measures

Homegrown eggs from free-ranging laying hens often contain elevated concentrations of perfluoroalkyl acids (PFAAs). However, it is unclear which factors contribute to these relatively large exposure risk scenarios. Moreover, existing bioavailability and modeling concepts of conventional organic pollutants cannot be generalized to PFAAs due to their different physicochemical soil interactions. Therefore, there is an urgent need for empirical models, based on real-world data, to provide insights into how (a)biotic factors affect the bioavailability to eggs. To this end, 17 targeted analytes were analyzed in abiotic (i.e. rainwater, soil; both N = 101) matrices and homegrown eggs (N = 101), which were sampled in 101 private gardens across Flanders (Belgium) in 2019, 2021 and 2022. Various soil characteristics were measured to evaluate their role in affecting PFAA bioavailability to the eggs. Finally, PFAAs were measured in potential feed sources (i.e. homegrown vegetable and earthworm pools; respectively N = 49 and N = 34) of the laying hens to evaluate their contribution to the egg burden. Modeling suggested that soil was a major exposure source to laying hens, accounting for 16-55% of the total variation in egg concentrations for dominant PFAAs. Moreover, concentrations in vegetables and earthworms for PFBA and PFOS, respectively, were significantly positively related with corresponding egg concentrations. Predictive models based on soil concentrations, total organic carbon (TOC), pH, clay content and exchangeable cations were successfully developed for major PFAAs, providing possibilities for time- and cost-effective risk assessment of PFAAs in homegrown eggs. Among other soil characteristics, TOC and clay content were related with lower and higher egg concentrations for most PFAAs, respectively. This suggests that bioavailability of PFAAs to the eggs is driven by complex physicochemical interactions of PFAAs with TOC and clay. Finally, remediation measures were formulated that are readily applicable to lower PFAA exposure via homegrown eggs.

Assessing per- and polyfluoroalkyl substances in globally sourced food packaging

The purpose of this study was to investigate the presence and levels of per- and polyfluoroalkyl substances (PFAS) in food packaging originating from different geographic locations. Food packaging samples were extracted and analyzed by targeted analysis with liquid chromatography-mass spectrometry (LC-MS/MS) before and after a total oxidizable precursor (TOP) assay. Additionally, full-scan high resolution MS (HRMS) was used to screen for PFAS not included in the targeted list. Of the 88 food packaging samples, 84% had detectable levels of at least one PFAS prior to oxidation with a TOP assay, with 6:2 fluorotelomer phosphate diester (6:2 diPAP) found most frequently and at the highest levels (224 ng/g). Other frequently detected substances (in 15-17% of samples) were PFHxS, PFHpA and PFDA. Shorter chain perfluorinated carboxylic acids PFHpA (C7), PFPeA (C5) and PFHxS (C6) were present at levels up to 51.3, 24.1 and 18.2 ng/g, respectively. Average ∑PFAS levels were 28.3 ng/g and 381.9 ng/g before and after oxidation with the TOP assay. The 25 samples with highest frequency of detection and amounts of measured PFAS were selected for migration experiments with food simulants to better understand potential dietary exposure. PFHxS, PFHpA, PFHxA and 6:2 diPAP were measured in the food simulants of five samples at concentrations ranging from 0.04 to 12.2 ng/g and at increasing concentrations over the 10-day migration period. To estimate potential exposure to PFAS that had migrated from food packaging samples, weekly intake was calculated and ranged from 0.0006 ng/kg body weight/week for PFHxA exposure in tomato packaging to 1.1200 ng/kg body weight/week for PFHxS exposure in cake paper. These values were below the established EFSA maximum tolerable weekly intake (TWI) of 4.4 ng/kg body weight/week for the sum of PFOA, PFNA, PFHxS and PFOS.

Inadequate definition of the limit of quantification used for the analysis of perfluoroalkyl substances in food by liquid chromatography-tandem mass spectrometry may compromise the reliability of the data requested by the European regulation

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a widespread technology used for the quantitative determination of per- and polyfluoroalkyl substances (PFAS) in foodstuff. Specifically, LC-MS/MS offers an attractive performance by combining the sensitivity and selectivity required by the European Union for testing perfluorooctane sulfonic acid, perfluorooctanoic acid, perfluorononanoic acid, and perfluorohexane sulfonic acid with maximum limits of quantification (LOQ) in the sub-parts-per-billion (μg/kg) or the parts-per-trillion (ng/kg) domains. In this article, we highlight the important diversity in LOQ definitions applied in LC-MS/MS methods described in the literature that raise concerns about the capability of some of those to generate reliable data requested by the European regulation. Here, we point out the risk of false response or misquantification if the criteria for assessing LOQ suffer from a lack of rigor. We emphasize the need to use PFAS-free samples spiked with the analyte(s) of interest and the application of identification criteria according to official documents for a sound measurement of the LOQ.

Effects of perfluorooctanoic acid (PFOA) on gene expression profiles via nuclear receptors in HepaRG cells: Comparative study with in vitro transactivation assays

Perfluorooctanoic acid (PFOA), a synthetic perfluorinated eight-carbon organic chemical, has been reported to induce hepatotoxicity, including increased liver weight, hepatocellular hypertrophy, necrosis, and increased peroxisome proliferation in rodents. Epidemiological studies have demonstrated associations between serum PFOA levels and various adverse effects. In this study, we investigated the gene expression profiles of human HepaRG cells exposed to 10 and 100 μM PFOA for 24h. Treatment with 10 and 100 μM PFOA significantly modulated the expression of 190 genes and 996 genes, respectively. In particular, genes upregulated or downregulated by 100µM PFOA included peroxisome proliferator-activated receptor (PPAR) signaling genes related to lipid metabolism, adipocyte differentiation, and gluconeogenesis. In addition, we identified the "Nuclear receptors-meta pathways" following the activation of other nuclear receptors: constitutive androstane receptor (CAR), pregnane X receptor (PXR) and farnesoid X receptor (FXR), and the transcription factor, nuclear factor E2-related factor 2 (Nrf2). The expression levels of some target genes (CYP4A11, CYP2B6, CYP3A4, CYP7A1, and GPX2) of these nuclear receptors and Nrf2 were confirmed using quantitative reverse transcription polymerase chain reaction. Next, we performed transactivation assays using COS-7 or HEK293 cells to investigate whether these signaling-pathways were activated by the direct effects of PFOA on human PPARα, CAR, PXR, FXR and Nrf2. PFOA activated PPARα in a concentration-dependent manner, but did not activate CAR, PXR, FXR, or Nrf2. Taken together, these results suggest that PFOA affects the hepatic transcriptomic responses of HepaRG cells through direct activation of PPARα and indirect activation of CAR, PXR FXR and Nrf2. Our finding indicates that PPARα activation found in the "Nuclear receptors-meta pathways" functions as a molecular initiating event for PFOA, and indirect activation of alternative nuclear receptors and Nrf2 also provide important molecular mechanisms in PFOA-induced human hepatotoxicity.

Up in the air: Polyfluoroalkyl phosphate esters (PAPs) in airborne dust captured by air conditioning (AC) filters

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously present in our indoor living environments. Dust is thought to accumulate PFAS released indoors and serve as an exposure pathway for humans. Here, we investigated whether spent air conditioning (AC) filters can be exploited as opportunistic samplers of airborne dust for assessing PFAS burden in indoor environments. Used AC filters from campus facilities (n = 19) and homes (n = 11) were analyzed for 92 PFAS via targeted ultra-high pressure liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS). While 27 PFAS were measured (in at least one filter), the predominant species were polyfluorinated dialkylated phosphate esters (diPAPs), with the sum of 6:2-, 8:2-, and 6:2/8:2diPAPs accounting for approximately 95 and 98 percent of ∑₂₇PFAS in campus and household filters, respectively. Exploratory screening of a subset of the filters revealed the presence of additional species of mono-, di-, and tri-PAPs. Considering the constant human exposure to dust indoors and the potential of PAPs to degrade into terminal species with well-established toxicological risks, assessing dust for these precursor PFAS warrants further investigation with respect to both human health and PFAS loading to landfills from this under studied waste stream.

PFASs in Soil: How They Threaten Human Health through Multiple Pathways and Whether They Are Receiving Adequate Concern

Per- and polyfluoroalkyl substances (PFASs) have been mass-produced and widely applied in consumer and industrial products, resulting in their widespread presence in the environment. Features such as environmental persistence, bioaccumulation, and high toxicity even at low doses have made PFASs an increasing concern. This brief review focuses on soil PFASs, especially the effect of soil PFASs on other environmental media and their potential threats to human health through daily diet. Specifically, soil PFASs contamination caused by different pathways was first investigated. Soil pollution from application of aqueous film-forming foams (AFFFs) is generally more severe than that from fluorochemical manufacturing plants, followed by biosolid land use, landfill, and irrigation. Factors, such as carbon chain length of PFASs, wastewater treatment technology, geographical conditions, and regional development level, are related to soil PFASs' pollution. Then, the migration, bioaccumulation, and toxicity characteristics of soil PFASs were analyzed. Short-chain PFASs have higher solubility, mobility, and bioavailability, while long-chain PFASs have higher bioaccumulation potential and are more toxic to organisms. Factors such as soil texture, solution chemistry conditions, enzymes, and fertilization conditions also influence the environmental behavior of PFASs. The risk of human exposure to PFASs through agricultural and animal products is difficult to control and varies depending on living region, age, eating habits, lifestyle, ethnicity, etc. Soil PFASs threaten drinking water safety, affect soil function, and enter food webs, threatening human health. Knowledge gaps and perspectives in these research fields are also included in current work to assist future research to effectively investigate and understand the environmental risks of soil PFASs, thereby reducing human exposure.

Direct evidence on occurrence of emerging liquid crystal monomers in human serum from E-waste dismantling workers: Implication for intake assessment

Liquid crystal monomers (LCMs) are widely used chemicals and ubiquitous emerging organic pollutants in the environment, some of which have persistent, bio-accumulative, and toxic potentials. Elevated levels of LCMs have been found in the e-waste dismantling associated areas. However, information on their internal exposure bio-monitoring is scarce. For the first time, occurrences of LCMs were observed in the serum samples of occupational workers (n = 85) from an e-waste dismantling area in South China. Twenty-nine LCMs were detected in serum samples of the workers, with a median value of 35.2 ng/mL (range: 7.78-276 ng/mL). Eight noticed LCMs were found to have relatively high detection frequencies ranging from 52.9% to 96.5%. The correlation analysis of individual LCMs indicated potential common applications and similar sources to the LCMs in occupational workers. Fluorinated LCMs were identified as the predominant monomers in the workers. Additionally, the estimated daily intake of the LCMs in the occupational workers was significantly higher than those in residents from the reference areas (p < 0.05, Mann-Whitney U Test, median values: 1.46 ng/kg bw/day versus 0.40 ng/kg bw/day), indicating a substantially higher exposure level to e-waste dismantling workers.