Estimating industrial process emission and assessing carbon dioxide equivalent of perfluorooctanoic acid (PFOA) and its salts in China

Atmospheric Emission of Per- and Polyfluoroalkyl Substances (PFAS) from a Fluoropolymer Manufacturing Facility: Focus on Emerging PFAS and the Potential Contribution of Condensable PFAS on their Atmospheric Partitioning

Fluoropolymer manufacturing facility (FMF) has been regarded as a main source of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in the atmosphere. In this study, suspect screening was performed to identify emerging PFAS in gas, particles, and dust both inside and outside a large FMF in China. A total of 74 emerging PFAS were tentatively identified with a confidence level of 3 or higher, 32 of which were reported in the environment for the first time. The semi-quantitative concentrations of the emerging PFAS, with perfluoroalkyl ether carboxylic acids (PFECAs) and Cl-PFECAs being predominant, accounted for 21-95% (mean: 46%) of the combined concentrations of emerging and legacy PFAS. Although the PFAS concentrations in the atmosphere decreased rapidly by more than 95% within 5 km, short-chain PFAS in PM2.5 were transported farther, especially C4 and C5 perfluoroalkyl carboxylic acids, which decreased by 66% and 79% within 5 km, respectively. Emerging PFAS with an ionic terminal group are mainly distributed in the particle phase, while alcohol-related PFAS are found in the gas phase. The ratios of PFAS in the gas phase inside the FMF were much higher than those outside, which could be reasonably explained by the condensation of gaseous PFAS onto fine particles shortly after being emitted.

Synergistic adsorption and photocatalytic degradation of perfluorooctanoic acid in aqueous solution by a regenerable biochar-titania nanotube composite

Perfluorooctanoic acid (PFOA), a recalcitrant perfluoroalkyl substance, presents escalating challenges for aquatic decontamination due to its extreme persistence and bioaccumulation. A biochar-titania nanotube (TNTs@biochar) combining the advantages of biochar and TNTs was synthesized for the first time via an alkaline hydrothermal approach and explored for the adsorption and photodegradation of PFOA in aqueous solution. Titania nanotubes interacted with biochar to form TNTs@biochar. The optimal composite was obtained at a biochar : TiO2 mass ratio of 1 : 1 and a calcination temperature of 550 °C. The composite efficiently adsorbed ∼99% of PFOA through hydrophobic and anion-π interactions and hydrogen bonding, concentrating PFOA on photoactive sites. The incorporation of biochar with TNTs enhanced light absorption in the 200-700 nm range, lowered the band gap energy to 3.10 eV, improved the formation rate and separation efficiency of e--h+ pairs, and enhanced interfacial charge transfer, resulting in promoted photocatalytic activity. The degradation of pre-concentrated PFOA on TNTs@biochar reached up to 99%. The photodegradation also regenerated the composite, allowing for four successive adsorption-photodegradation cycles. Hydroxyl radical and h+-driven oxidation played a paramount part, leading to decarboxylation and C-F bond cleavage. The byproducts of the photodegradation demonstrated lower acute and chronic toxicity compared with PFOA. The composite exhibits synergistic adsorption and photocatalytic activity as well as offers efficiently and economically scalable solutions for PFOA-laden water remediation.

Estimating wastewater emissions and environmental levels of typical organic contaminants based on regionalized modelling

Organic contaminants (OCs) are released into the environment through effluent discharges from wastewater treatment plants (WWTP), posing risks to environment health. However, emissions from various source, particularly large-scale investigations across different industries, remain poorly understood. Based on both sampling and statistical data, this study estimates the emissions of 10 OCs, including perfluorooctane acid (PFOA), perfluorooctane sulfonate (PFOS), 4-nonylphenol (4-NP), 4-tert-octylphenol (4-t-OP), dibutyl phthalate (DBP), di-iso-butyl phthalate (DIBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and bisphenol A (BPA), from the effluents of 160 factories across 8 industries, 541 municipal wastewater treatment plants (MWWTPs), and 8 waste treatment plants (WTPs) in the upper Yangtze River Basin. A level III fugacity multimedia model was used to assess the impacts of these emissions on local watersheds. Among the 8 industries, paper production was the largest contributor, accounting for over 80% of total OC emissions, which amounted to 89.1 kg/yr. The contributions of domestic and industrial sources were 91.5% and 8.5%, respectively, underscoring the predominance of domestic sources in the release of the 10 OCs. PFOA emerged as the most dominant compound, with total emissions amounting to 4464 kg/yr from domestic sources and 170 kg/yr from industrial sources. The predicted concentrations of OCs in the receiving rivers closely aligned with values reported in existing literature, differing by no more than one order of magnitude. To our knowledge, this is the first comprehensive report on emissions from various sources in the upper Yangtze River Basin.

Individual and joint associations of exposure to per- and polyfluoroalkyl substances with children's mitochondrial DNA copy number, and modified by estimated glomerular filtration rate

BACKGROUND

The association between per- and polyfluoroalkyl substances (PFAS) and mitochondrial DNA copy number (mtDNAcn) in children, and the potential impact of estimated glomerular filtration rate (eGFR) on this association, remains unclear.

METHODS

We conducted a panel study with up to 3 surveys over 3 seasons in Weinan and Guangzhou, China. A total of 284 children aged 4-12 years were available, with 742 measurements of 11 PFAS and mtDNAcn. Linear mixed-effect (LME), quantile g-computation (qgcomp), weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to investigate the associations of individuals and a mixture of PFAS with mtDNAcn, and the modifying effect of eGFR on these associations.

RESULTS

Legacy PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorooctane sulfonate (PFOS) and emerging PFAS, 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), were significantly associated with decreased mtDNAcn in a linear dose-response manner (FDR <0.05). The multiple PFAS model showed each doubling increase in PFOA related to a 6.36% (95%CI: -10.22%, -2.34%) decrement in mtDNAcn. Meanwhile, the PFAS mixture was dose-responsive related to decreased mtDNAcn, with PFOA being the largest contributor, followed by PFUnDA and PFNA. Notably, eGFR modified the inverse association between PFOA and mtDNAcn (P-int = 0.039), with a more pronounced decrement in children with an eGFR below the 20th value (101.71 mL/min/1.73m2). In addition, age significantly modified the relationship between PFOA and decreased mtDNAcn (P-int = 0.028), with a stronger association in those aged 7 years or older.

CONCLUSION

Both individual and the mixture of legacy and emerging PFAS exposure were associated with decreased mtDNAcn in children, with PFOA as the main contributor and modification of eGFR.

Perfluorooctanoic acid induces transgenerational modifications in reproduction, metabolism, locomotor activity, and sleep behavior in Drosophila melanogaster and deleterious effects in human cancer cells

Perfluorooctanoic acid (PFOA) has been widely documented to affect various aspects of health, including development, metabolism and neuronal function in a variety of organisms. Despite numerous reports detailing these effects, a comprehensive mechanistic model remains elusive, especially with regard to the long-term effects of PFOA, as it bioaccumulates in food chains with a long half-life. In this study, we evaluated the impact of PFOA on several critical physiological states of Drosophila melanogaster. Our findings indicate that PFOA exposure significantly decreases reproductive capacity and induces alterations in starvation resistance and feeding behavior in flies. Interestingly, PFOA exposure also caused changes in locomotor activity and sleep patterns compared with flies receiving a standard diet. Notably, compared with controls, the F2 generation showed increased locomotion and shorter sleep duration during the dark phase, even without direct exposure to PFOA, indicating possible transgenerational effects. Transcriptomic analysis revealed that PFOA also disrupts fatty acid metabolism and alters the expression of immune-responsive genes in Drosophila. In the U-2 OS human osteosarcoma cell line, we examined the impact of PFOA on circadian rhythm regulatory proteins and discovered that, compared with controls, BMAL1 levels increased at concentrations from 10 nM to 10 μM. In summary, this research highlights the influence of PFOA on diverse biological processes, including reproduction, feeding behavior, starvation resistance, locomotion, and sleep activity in Drosophila. It also highlights the ability of PFOA to alter BMAL1 expression patterns in human osteosarcoma cells with deleterious effects.

Fate, distribution, and transport dynamics of Per- and Polyfluoroalkyl Substances (PFASs) in the environment

Per- and Polyfluoroalkyl Substances (PFASs) are persistent organic pollutants with significant environmental and health impacts due to their widespread occurrence, bioaccumulation potential, and resistance to degradation. This paper comprehensively reviews current knowledge of PFAS fate and transport mechanisms by correlating PFAS leaching, retention, and movement to their physicochemical properties and environmental factors based on observing PFAS fate and transport in unsaturated zones, surface water, sediments, plants, and atmosphere. The complex and unique physiochemical properties of PFASs, such as their carbon-fluorine bonds and amphiphilic nature, determine their environmental behavior and persistence. Recent studies emphasize that concentration-dependent affinity coefficients predict the transport of diverse PFAS mixtures by considering the impact of the Air-Water Interface (AWI). These studies highlight the complex interactions that influence PFAS behavior in environmental systems and the need for refined modeling techniques to account for transport dynamics. Competitive adsorption at the AWI, influenced by PFAS physicochemical properties and environmental factors, is crucial. PFAS chain length profoundly affects PFAS volatility and mobility, i.e., longer chains show higher solid matrix adsorption, while shorter chains exhibit greater atmospheric deposition potential. Solution chemistry, encompassing pH and ionic strength, variably alters PFAS sorption behaviors. Mathematical models, such as the Leverett Thermodynamic Model (LTM) and Surface Roughness Multipliers (SRM), effectively predict PFAS retention, offering enhanced accuracy for surface-active solutes through empirical adjustments. Co-contaminants' presence influences the transport behavior of PFASs in the environment. Microbial activity alters PFAS retention, while microplastics, especially polyamide, contribute to their adsorption. These complex interactions govern PFAS fate and transport in the environment. The paper identifies critical gaps in current understanding, including the fate of PFASs, analytical challenges, ecological risk assessment methods, and the influence of episodic events on PFAS transport dynamics. This paper also investigates the research gap in refining current models and experimental approaches to predict PFAS transport accurately and enhance risk mitigation efforts. Addressing these gaps is crucial for advancing remediation strategies and regulatory frameworks to mitigate PFAS contamination effectively.

Spatial distribution, compositional characteristics, and source apportionment of legacy and novel per- and polyfluoroalkyl substances in farmland soil: A nationwide study in mainland China

China, as one of the largest global producers and consumers of per- and poly-fluoroalkyl substances (PFASs), faces concerning levels of PFAS pollution in soil. However, knowledge of their occurrence in agricultural soils of China on the national scale remains unknown. Herein, the first nationwide survey was done by collecting 352 soil samples from 31 provinces in mainland China. The results indicated that the Σ24PFASs concentrations were 74.3 - 24880.0 pg/g, with mean concentrations of PFASs in decreasing order of legacy PFASs > emerging PFASs > PFAS precursors (640.2 pg/g, 340.7 pg/g, and 154.9 pg/g, respectively). The concentrations in coastal eastern China were distinctly higher than those in inland regions. Tianjin was the most severely PFASs-contaminated province because of rapid urban industrialization. This study further compared the PFAS content in monoculture and multiple cropping farmland soils, finding the concentrations of PFASs were high in soils planted with vegetable and fruit monocultures. Moreover, a positive matrix factorization (PMF) model was employed to identify different sources of PFASs. Fluoropolymer industries and aqueous film-forming foams were the primary contributors. The contributions from different emission sources varied across the seven geographical regions. This study provides new baseline data for prevention and control policies for reducing pollution.

Inulin alleviates perfluorooctanoic acid-induced intestinal injury in mice by modulating the PI3K/AKT/mTOR signaling pathway

Perfluorooctanoic acid (PFOA) is a widely used industrial compound that has been found to induce intestinal toxicity. However, the underlying mechanisms have not been fully clarified and effective interventions are rarely developed. Inulin, a prebiotic, has been used as a supplement in human daily life as well as in gastrointestinal diseases and metabolic disorders. In this study, male mice were exposed to PFOA with or without inulin supplementation to investigate the enterotoxicity and potential intervention effects of inulin. Mice were administered PFOA at 1 mg/kg/day, PFOA with inulin at 5 g/kg/day, or Milli-Q water for 12 weeks. Histopathological analysis showed that PFOA caused colon shortening, goblet cell reduction, and inflammatory cell infiltration. The expression of the tight junction proteins ZO-1, occludin and claudin5 significantly decreased, indicating impaired barrier function. According to the RNA-sequencing analysis, PFOA exposure resulted in 917 differentially expressed genes, involving 39 significant pathways, such as TNF signaling and cell cycle pathways. In addition, the protein expression of TNF-α, IRG-47, cyclinB1, and cyclinB2 increased, while Gadd45γ, Lzip, and Jam2 decreased, suggesting the involvement of the TNF signaling pathway, cell cycle, and cell adhesion molecules in PFOA-associated intestinal injury. Inulin intervention alleviated PFOA-induced enterotoxicity by activating the PI3K/AKT/mTOR signaling pathway and increasing the protein expression of Wnt1, β-catenin, PI3K, Akt3, and p62, while suppressing MAP LC3β, TNF-α, and CyclinE expression. These findings suggested that PFOA-induced intestinal injury, including inflammation and tight junction disruption, was mitigated by inulin through modifying the PI3K/AKT/mTOR signaling pathways. Our study provides valuable insights into the enterotoxic effects of PFOA and highlights the potential therapeutic role of inulin.

Occurrence of legacy and alternative per- and polyfluoroalkyl substances in serum from high exposure population and their disrupting effects on serum lipids and thyroid function

High exposure of per- and polyfluoroalkyl substances (PFAS) has been reported in main chemical production areas in China, while epidemiological study on exposure risk of PFAS is still limited. In this study, legacy and alternative PFAS were measured in serum samples from 161 adults living in Laizhou Bay, a famous chemical production area located in Shandong province, Northern China. Based on the concentrations of serum PFAS, the disrupting effects of PFAS on serum lipids and thyroid function were further explored. The results showed that the serum perfluorooctanoic acid (PFOA) (geometric mean (GM): 60 ng/mL) in this region was even higher than serum PFOA of residents living in PFOA contaminated water districts in United States and Sweden. 100 % of the serum PFOA was higher than the reference dose for increased total cholesterol (TC). Consistently, higher serum PFOA was marginally correlated with increased TC level (p = 0.062) and low-density lipoprotein (p = 0.065). In addition, higher perfluoroisopropyl perfluorooctanesulfonate and 6:2 chlorinated polyfluoroalkyl ether sulfonates (6,2 Cl-PFESA) were significantly correlated with increased high-density lipoprotein (p = 0.040, 0.022). No significant association was observed between individual PFAS and any thyroid function biomarker. However, using the principal component analysis derived factors to represent the co-exposure patterns, co-exposure of legacy long-chain PFAS showed synergistic effects on the free thyroxine, while the mixture of alternative PFAS showed a synergistic influence on the total and free triiodothyronine.