Vital Environmental Sources for Multitudinous Fluorinated Chemicals: New Evidence from Industrial Byproducts in Multienvironmental Matrices in a Fluorochemical Manufactory

Spatial distribution, source, and fate of per- and polyfluoroalkyl substances in the surrounding environment of closed and converted fluorochemical factories in Fujian, China

Following the closure of perfluorooctanesulfonic acid (PFOS) production to comply with the Stockholm Convention regulations or restrictions, manufacturers have shifted to developing short-chain alternatives like perfluorobutane sulfonic acid (PFBS). However, limited research has been conducted to evaluate the impact of this transition on the surrounding environment. This study focused on the spatial distribution, source, and fate of 18 per- and polyfluoroalkyl substances (PFAS) in the surrounding environment of the closure and transformation of two PFAS manufacturing plants in Fujian, China. The total concentrations of PFAS in surface water, sediment, and fish were within the range of 48.9-72,400 ng/L, 0.930-57.6 ng/g dw, and 3.33-1245 ng/g dw, respectively. The predominant compounds were PFBS, PFOS, and perfluorooctanoic acid (PFOA) among the three matrices. Principal component analysis highlighted significant differences in PFAS profiles across different regions of the Futun River, suggesting diverse sources of PFAS. Source apportionment indicated that despite being closed or converted for almost three years, the two factories still significantly impacted the surrounding environment. The shutdown factory mainly released PFAS characterized by perfluoroalkyl sulfonic acids. In contrast, the PFAS were released from conversion plant with the fingerprint being PFBS and perfluoroalkyl carboxylic acids. The conversion of the factories has resulted in the coexistence of long-chain and short-chain PFAS, which has complicated the composition of PFAS in the environment. As sewage treatment plant could not effectively remove PFBS and perfluorobutanoic acid (PFBA) in wastewater, and due to their strong migration ability, these chemicals had a wider impact range, increasing the difficulty of environmental restoration and management. Risk assessment showed that PFAS downstream of the two factories posed high or moderate ecological risks. Specifically, PFBS, PFOS, and PFOA displayed the highest risk quotients and should be paid further attention.

Occurrence and profiles of perfluoroalkyl substances in wastewaters of chemical industrial parks and receiving river waters: Implications for the environmental impact of wastewater discharge

A total of 17 groups of wastewaters from the chemical industrial parks and matched receiving river waters were collected in the east of China. The measured total concentrations of 21 analyzed PFAS analogues (∑21PFAS) in the influents and effluents of the wastewater treatment plants (WWTPs) were in the range of 0.172-20.6 μg/L (mean: 18.2 μg/L, median: 3.9 μg/L) and 0.167-93.6 μg/L (mean: 10.8 μg/L, median: 1.12 μg/L), respectively, which were significantly higher than those observed in the upstream (range: 0.0158-7.05 μg/L, mean: 1.09 μg/L, median: 0.482 μg/L) and downstream (range: 0.0237-1.82 μg/L, mean: 0.697 μg/L, median: 0.774 μg/L) receiving waters. Despite the concentrations and composition profiles of PFAS varied in the water samples from different sampling sites, PFOA was generally the major PFAS analogue in the research areas, mainly due to the history of PFOA production and usage as well as the specific exemptions. The calculated concentration ratios of the short-chain PFCAs and PFSAs to their respective predecessors (PFOA and PFOS) in most of the samples far exceeded 1, indicating a shift from legacy PFOA and PFOS to short-chain PFAS in the research areas. Correlation network analysis and the calculated concentration ratios of PFAS in the effluents versus influents indicated transformation may have occurred during the water treatment processes and PFAS could not be efficiently removed in the WWTPs. Wastewater discharge of chemical industrial parks is a vital source of PFAS dispersed into the aquatic environment.

Nontarget Discovery of Per- and Polyfluoroalkyl Sulfonyl Halides in Soils by Integration of Derivatization and Specific Fragment-Based Liquid Chromatography-High Resolution Mass Spectrometry Screening

Though long recognized as synthetic precursors to other poly- and perfluoroalkyl substances (PFASs), most poly- and perfluoroalkyl sulfonyl halides (PASXs) cannot be directly measured and have generally received minimal attention. Inspired by the redox reaction between sulfonyl halide groups and p-toluenethiol in organic chemistry, we developed a novel nontarget analysis strategy for PASXs by intergrating derivatization and specific fragment-based liquid chromatography-high resolution mass spectrometry screening for m/z 82.961 [SO2F-] and m/z 95.934 [S2O2-]. By using this strategy, we discovered 11 PASXs, namely, perfluoroalkyl sulfonyl fluorides (5), polyfluoroalkyl sulfonyl fluorides (2), unsaturated perfluoroalkyl sulfonyl fluoride (1), and perfluoroalkyl sulfonyl chlorides (3) in soil samples collected from an abandoned fluorochemical manufacturing park. These average ∑PASXs concentrations were 1120 μg kg-1 (range: 9.7-9860 μg kg-1), which were very likely to be the key intermediates and undesired byproducts of electrochemical fluorination processes. Spatial variation in the mass ratio of ∑PASXs to ∑PFSAs (range: 0.7-795%) also indicates their different transportation pathways. More importantly, the decline of PASXs and increase of perfluoroalkyl sulfonates (when compared to a prior study at this site) suggest the continued hydrolysis of PASXs and the relatively fast environmental transformation rates in the abandoned fluorochemical park soils. Overall, these findings demonstrated the utility of a novel nontarget analysis strategy, which may change most PASXs from inferred precursors to measured intermediates and further could be adapted for structures, distribution, and transformation studies of PFASXs in other matrices.

Biological effects of perfluoroalkyl substances on running water ecosystems: A case study in Beiluo River, China

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that pose a threat to the biodiversity of the Beiluo River, a polluted watercourse on the Loess Plateau impacted by diverse human activities. However, the occurrence, spatial distribution, and substitution characteristics of PFASs in this region remain unclear. This study aimed to unravel PFAS distribution patterns and their impact on the aquatic ecosystems of the Beiluo River Basin. The total PFAS concentration in the area ranged from 16.64-35.70 ng/L, with predominantly perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), collectively contributing 94%. The Mantel test revealed threats to aquatic communities from both legacy long-chain (perfluorooctanoic acid and sodium perfluorooctane sulfonic acid) and emerging (6:2 fluorotelomer sulfonic acid, 2-Perfluorohexyl ethanoic acid, and hexafluoropropylene oxide dimer acid (Gen-X)) PFSAs. The canonical correspondence analysis ordination indicated that trace quantities of emerging PFASs, specifically 2-Perfluorohexyl ethanoic acid and hexafluoropropylene oxide dimer acid (Gen-X), significantly influenced geographical variations in aquatic communities. In conclusion, this study underscores the importance of comprehensively exploring the ecological implications and potential risks associated with PFASs in the Beiluo River Basin.

Profiles and transplacental transfer of per- and polyfluoroalkyl substances in maternal and umbilical cord blood: A birth cohort study in Zhoushan, Zhejiang Province, China

Per- and polyfluoroalkyl substances (PFAS) can pass through the placental barrier and pose health risks to fetuses. However, exposure and transplacental transfer patterns of emerging PFAS remain unclear. Here, 24 PFAS were measured in paired maternal whole blood (n = 228), umbilical cord whole blood (n = 119) and serum (n = 120). Orthogonal partial least-squares discriminant analysis (OPLS-DA) was used to differentiate PFAS between different matrices. The transplacental transfer (TPT) of PFAS was calculated using cord to maternal whole blood concentration ratios. PFOS and PFOA were still the dominant PFAS in maternal samples. The emerging PFAS had higher TPT than PFOS and PFOA. Moreover, PFAS with the same chain length but different functional groups and C-F bonds showed different TPT, such as PFOS and PFOSA (C8, median: 0.090 vs. 0.305, p < 0.05) and PFHxS and 4:2 FTS (C6, median: 0.220 vs. 1.190, p < 0.05). A significant sex difference in 4:2 FTS (median: boys 1.250, girls 1.010, p < 0.05) were found. Furthermore, we observed a significant U-shaped trend for the TPT of carboxylates with increasing carbon chain length. PFAS showed a compound-specific transfer through placental barrier and a compound-specific distribution between different matrices in this study.

Heterogeneous Photodegradation Behavior of Liquid Crystal Monomers in Dust: Quantitative Structure-Activity Relationship and Product Identification

The heterogeneous photodegradation behavior of liquid crystal monomers (LCMs) in standard dust (standard reference material, SRM 2583) and environmental dust was investigated. The measured photodegradation ratios for 23 LCMs in SRM and environmental dust in 12 h were 11.1 ± 1.8 to 23.2 ± 1.1% and 8.7 ± 0.5 to 24.0 ± 2.8%, respectively. The degradation behavior of different LCM compounds varied depending on their structural properties. A quantitative structure-activity relationship model for predicting the degradation ratio of LCMs in SRM dust was established, which revealed that the molecular descriptors related to molecular polarizability, electronegativity, and molecular mass were closely associated with LCMs' photodegradation. The photodegradation products of the LCM compound 4'-propoxy-4-biphenylcarbonitrile (PBIPHCN) in dust, including •OH oxidation, C-O bond cleavage, and ring-opening products, were identified by nontarget analysis, and the corresponding degradation pathways were suggested. Some of the identified products, such as 4'-hydroxyethoxy-4-biphenylcarbonitrile, showed predicted toxicity (with an oral rat lethal dose of 50%) comparable to that of PBIPHCN. The half-lives of the studied LCMs in SRM dust were estimated at 32.2-82.5 h by fitting an exponential decay curve to the observed photodegradation data. The photodegradation mechanisms of LCMs in dust were revealed for the first time, enhancing the understanding of LCMs' environmental behavior and risks.

Legacy and alternative per-and polyfluoroalkyl substances (PFASs) in the Bohai Bay Rim: Occurrence, partitioning behavior, risk assessment, and emission scenario analysis

The use of alternative per- and polyfluoroalkyl substances (PFASs) has been practiced because of the restrictions on legacy PFASs. However, knowledge gaps exist on the ecological risks of alternatives and relationships between restrictions and emissions. This study systematically analyzed the occurrence characteristics, water-sediment partitioning behaviors, ecological risks, and emissions of legacy and alternative PFASs in the Bohai Bay Rim (BBR). The mean concentration of total PFASs was 46.105 ng/L in surface water and 6.125 ng/g dry weight (dw) in sediments. As an alternative for perfluorooctanoic acid (PFOA), hexafluoropropylene oxide dimer acid (GenX) had a concentration second only to PFOA in surface water. In sediments, perfluorobutyric acid (PFBA) and GenX were the two predominant contaminants. In the water-sediment partitioning system, GenX, 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (F-53B), and 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (8:2 Cl-PFESA) tended to be enriched towards sediments. The species sensitivity distribution (SSD) models revealed the low ecological risks of PFASs and their alternatives in the BBR. Moreover, predicted no-effected concentrations (PNECs) indicated that short-chain alternatives like PFBA and perfluorobutane sulfonate (PFBS) were safer for aquatic ecosystems, while caution should be exercised when using GenX and F-53B. Due to the incremental replacement of PFOA by GenX, cumulative emissions of 1317.96 kg PFOA and 667.22 kg GenX were estimated during 2004-2022, in which PFOA emissions were reduced by 59.2 % due to restrictions implemented since 2016. If more stringent restrictions are implemented from 2023 to 2030, PFOA emissions will further decrease by 85.0 %, but GenX emissions will increase by an additional 21.3 %. Simultaneously, GenX concentrations in surface water are forecasted to surge by 2.02 to 2.45 times in 2023. This study deepens the understanding of PFAS alternatives and assists authorities in developing policies to administer PFAS alternatives.

Distribution of select per- and polyfluoroalkyl substances at a chemical manufacturing plant

Per- and polyfluoroalkyl substances (PFAS) are used in various industrial products; however, they pose serious health risks. In this study, soil, soil gas, and groundwater samples were collected at a PFAS manufacturing facility in New Jersey, USA, to determine the presence and distribution of PFASs from the soil surface to groundwater and at various distances from the presumed source. Fluorotelomer alcohols (FTOHs) were detected in soil (< 0.26-36.15 ng/g) and soil gas (160-12,000 E µg/m3), while perfluorinated carboxylic acids (PFCAs) were found in soil (4.3-810 ng/g), soil gas (<0.10-180 µg/m3), and groundwater (37-49 µg/L). FTOH and PFCA concentrations decreased as the distance from the presumed source increased, suggesting that PFCAs are likely to migrate in groundwater, whereas FTOHs primarily move in the vapor phase. The presence of PFAS in the groundwater, soil, and soil gas samples indicate its potential for vapor intrusion; thus, some PFAS may contribute to indoor air inhalation exposure. To the best of our knowledge, this is the first report on the quantification of volatile PFAS in soil gas at a PFAS manufacturing facility.

Nontarget Analysis and Comprehensive Characterization of Iodinated Polyfluoroalkyl Acids in Wastewater and River Water by LC-HRMS with Cascade Precursor-Ion Exclusions and Algorithmic Approach

Poly- and perfluoroalkyl acids (PFAAs) are a large family of widespread contaminants of worldwide concern and well-known as "forever chemicals". Direct emission of PFAAs from the fluorochemical industry is a crucial source of PFAA pollutants in the environment. This study implemented nontarget analysis and comprehensive characterization for a category of new PFAA contaminants, i.e., iodinated PFAAs (IPFAAs), in fluorochemical industry wastewater and relevant contaminated river water by liquid chromatography-high-resolution mass spectrometry with a cascade precursor ion exclusion (PIE) strategy and in-house developed data extraction and processing algorithms. A total of 26 IPFAAs (including 2 isomers of an IPFAA) were found and identified with tentative molecular structures. Semiquantification of the IPFAAs was implemented, and the total concentrations of IPFAAs were 0.16-285.52 and 0.15-0.17 μg/L in wastewater and river water, respectively. The high concentrations in association with the predicted ecotoxicities and environmental behaviors demonstrate that these IPFAAs are worthy of more concern and further in-depth research. The cascade PIE strategy along with the data extraction and processing algorithms can be extended to nontarget analysis for other pollutants beyond IPFAAs. The nontarget identification and characterization outcomes provide new understanding on the environmental occurrence and pollution status of IPFAAs from a comprehensive perspective.

Insight into the mechanisms of neuroendocrine toxicity induced by 6:2FTCA via thyroid hormone disruption

6:2 fluorotonic carboxylic acid (6:2 FTCA), a novel substitute for perfluorooctanoic acid (PFOA), is being used gradually in industrial production such as coatings or processing aids, and its detection rate in the aqueous environment is increasing year by year, posing a potential safety risk to aquatic systems and public health. However, limited information is available on the effects and mechanism of 6:2 FTCA. Therefore, this study was conducted to understand better the neuroendocrine effects of early exposure to 6:2 FTCA and the underlying mechanisms on zebrafish. In this study, zebrafish embryos were treated to varied doses of 6:2 FTCA (0, 0.08 μg/mL, 0.8 μg/mL and 8 μg/mL) at 4 h post-fertilization (hpf) for a duration of six days, which exhibited a pronounced inhibition of early growth and induced a disorganized swim pattern characterized by reduced total swim distance and average swim speed. Simultaneously, the thyroid development of zebrafish larvae was partially hindered, accompanied by decreased T3 levels, altered genes associated with the expression of thyroid hormone synthesis, transformation and transportation and neurotransmitters associated with tryptophan and tyrosine metabolic pathways. Molecular docking results showed that 6:2 FTCA has a robust binding energy with the thyroid hormone receptor (TRβ). Moreover, exogenous T3 supplementation can partially restore the adverse outcomes. Our findings indicated that 6:2 FTCA acts as a thyroid endocrine disruptor and can induce neuroendocrine toxic effects. Furthermore, our results show that targeting TRβ may be a potentially therapeutic strategy for 6:2 FTCA-induced neuroendocrine disrupting effects.

Novel Insights into the Adverse Health Effects of per- and Polyfluoroalkyl Substances on the Kidney via Human Urine Metabolomics

Per- and polyfluoroalkyl substances (PFAS) receive significant research attention due to their potential adverse effects on human health. Evidence shows that the kidney is one of the target organs of PFAS. In occupational exposure scenarios, high PFAS concentrations may adversely affect kidney metabolism, but whether this effect is reflected in the small metabolic molecules contained in urine remains unknown. In this study, 72 matched serum and urine samples from occupational workers of a fluorochemical manufactory as well as 153 urine samples from local residents were collected, and 23 PFAS levels were quantified. The concentrations of Σ23PFAS in the serum and urine samples of workers were 5.43 ± 1.02 μg/mL and 201 ± 46.9 ng/mL, respectively, while the Σ23PFAS concentration in the urine of the residents was 6.18 ± 0.76 ng/mL. For workers, high levels of urinary PFAS were strongly correlated with levels in serum (r = 0.57-0.93), indicating that urinary PFAS can be a good indicator for serum PFAS levels. Further, a urine nontargeted metabolomics study was conducted. The results of association models, including Bayesian kernel machine regression, demonstrated positive correlations between urinary PFAS levels and key small kidney molecules. A total of eight potential biomarkers associated with PFAS exposure were identified, and all of them showed significant positive correlations with markers of kidney function. These findings provide the first evidence that urine can serve as a matrix to indicate the adverse health effects of high levels of exposure to PFAS on the kidneys.

Target and nontarget analysis of per- and polyfluoroalkyl substances in surface water, groundwater and sediments of three typical fluorochemical industrial parks in China

The objectives of this study were to identify both legacy and emerging per- and polyfluoroalkyl substances (PFAS) from three typical fluoridated industrial parks (FIPs) in China, and to assess their environmental occurrence and fate. Complementary suspect target and nontarget screening were implemented, and a total of 111 emerging PFAS were identified. Based on the multi-mass scale analysis, 25 emerging PFAS were identified for the first time, including 24 per- and polyfluoroalkyl ether carboxylic acids (PFECAs) and 1 ultra-short chlorinated perfluoroalkyl carboxylic acids (Cl-PFCAs, C2), with a maximum percentage of 48.2 % in nontarget PFAS (exclude target PFAS). The composition of PFAS identified in different media was influenced by functional groups, carbon chain length, substituents and ether bond insertion, with poly-hydrogen substituted being preferably in water and a more diverse pattern of PFECAs in sediments. The patterns of PFAS homologs revealed distinct differences among the three typical FIPs in the shift of PFAS production patterns. The C4-PFAS and short-chain carboxylic acids (≤C6) were the main PFAS in the Fuxin and Changshu, respectively. In contrast, perfluorooctanoic acid (PFOA, C8) remained dominant in Zibo, and the highest point concentrations in water and sediment were up to 706 µg/L and 553 µg/g, respectively.

Monitoring the adsorption of per- and polyfluoroalkyl substances on carbon black by LDI-MS capable of simultaneous analysis of elemental and organic carbon

Elemental carbon (EC) and organic carbon (OC) exist ubiquitously and interact mutually in the environment. Simultaneous analysis of EC and OC will greatly advance our understanding of the behavior and fate of EC and OC, but is however still a great challenge due to the lack of suitable analytical tools. Here, we report a matrix-free laser desorption/ionization mass spectrometry (LDI-MS) method capable of simultaneous analysis of EC and OC by monitoring two independent groups of specific MS fingerprint peaks. We found that EC itself can generate carbon cluster peaks in the low mass range under laser excitation, and meanwhile it can also serve as a matrix to assist the ionization of OC in LDI-MS. By using per- and polyfluoroalkyl substances (PFASs) as a typical set of OC and carbon black (CB) as a model EC, we successfully monitored the adsorption process of PFASs on CB enabled by LDI-MS. We show that hydrophobic interaction dominates the sorption of PFASs to CB, which was affected by the functional groups and carbon chain length of PFASs. Furthermore, environmental substances in water such as humic acid (HA) and surfactants can significantly affect the adsorption of PFASs on CB probably by changing the adsorption sites of CB. Overall, we demonstrate that LDI-MS offers a versatile and high-throughput tool for simultaneous analysis of EC and OC species in real environmental samples, which makes it promising for investigating the environmental behaviors and ecological risks of pollutants.

Variations of the Level, Profile, and Distribution of PFAS around POSF Manufacturing Facilities in China: An Overlooked Source of PFCA

The occurrence of per- and polyfluoroalkyl substances (PFAS) was investigated inside two manufacturing facilities in China. Levels, profiles, and spatial distribution of the detected PFAS were found to be distinctly site-specific and influenced by the area's historic function, production structure of the plant, downpour-induced accidental pollution, and variations in the adsorption and transport of compounds. Very high concentrations of PFAS [mainly C4 and C8 perfluoroalkyl sulfonic acids (PFSAs)] were found in topsoil and groundwater from both plants, with the highest values of 4.89 × 10⁶ μg/kg dw and 1.10 × 10⁴ μg/L, respectively. Elevated concentrations of perfluoroalkyl carboxylic acids (PFCAs) in this study were attributed to their unintentional formation during the electrochemical fluorination process, which might be an overlooked source of PFCA. PFAS generally showed decreasing trends from shallow layers to the bottom of the soil core and demonstrated some downward migrations at different soil depths with time, and C4-C8 PFAS presented a deeper seepage than their long-chain homologues. Total organic carbon appeared to be more important for PFAS sorption to the topsoil than to the soil core. Workers were at potential risk of exposure to perfluorooctanesulfonic acid via soil at production and storage related sites. This study provides a critical reference for the systematic control of PFAS pollution around manufacturing facilities and a proof for an overlooked source of PFCA.

Evaluating Neutral PFAS for Potential Dermal Absorption from the Gas Phase

Exposures to per- and polyfluoroalkyl substances (PFAS) are of increasing concern. Assessments typically focus only on ingestion and inhalation exposure due to a lack of generally accepted approaches for estimating dermal absorption. Prior work indicates limited dermal absorption of ionic PFAS, but absorption of neutral PFAS has not been examined from the liquid vehicle or from vapor. Partitioning of semivolatile organic compounds from the gas phase to the skin surface (i.e., stratum corneum) is well known, but the potential for partitioning of neutral PFAS from the gas phase to the stratum corneum has yet to be estimated. The SPARC-estimated physicochemical properties were used to calculate transdermal permeability coefficients (k_{p_g}) and dermal-to-inhalation (D/I) exposure ratios for two groups of neutral PFAS, including those on a U.S. Environmental Protection Agency PFAS list. 11 neutral PFAS gave calculated D/I ratios >5, indicating that direct transdermal absorption may be an important exposure pathway compared to inhalation. Data on consumer products or indoor air is needed for the 11 neutral PFAS, followed by possible biomonitoring to experimentally verify dermal absorption from air. Additional PFAS should be estimated by the protocol used here as they are identified in commercial products.

Isomer-specific perfluoroalkyl acids accumulation, excretion and maternal transfer to eggs in chickens around a fluorochemical manufactory in China

The co-existing of multiple Per- and polyfluoroalkyl substances (PFASs) might pose more complicated situation for the exposure risk of environment and biota, especially for the surrounding area of the contaminated communities. In this study, tissues and organs of free-ranged chickens, paired eggs, corresponding feces, water, soil/dust, and feed samples around a fluorochemical manufactory were collected to investigate the tissue-isomer-specific accumulation, elimination and maternal transfer to eggs of PFASs. Free-ranged chickens had much higher ∑PFASs concentrations than farm chickens, and PFBA and PFOS were the predominant PFASs in tissues and organs, which is consistence with the electrochemical fluorination (ECF) production pattern of this manufactory. This result implied that PFASs released from manufactory production is a direct exposure source to the chickens. ∑PFASs concentrations in yolk samples were higher than other tissues and organs, while the concentrations in albumen were lowest. Isomer profiles analysis indicated that n-PFOS proportions in tissues, organs, yolk, and albumen ranged from 85.3 %-98.1 %, whereas in the feces with the percentage of 72.9 %, indicating that the branched PFOS isomers showed faster excretion rate than n-PFOS for chickens. Resident's estimated daily intakes (EDIs) of ∑PFASs via chicken were in the range of 6.41 to 107.18 ng/kg·bw/d. Notably, the EDIs of the sum of four PFASs were higher than the TDI of EFSA in 2020, indicating potential health risks.