Chlorinated polyfluoroalkyl ether sulfonic acids in fish, dust, drinking water and human serum: From external exposure to internal doses

Environmental occurrence, bioaccumulation and human risks of emerging fluoroalkylether substances: Insight into security of alternatives

Per- and polyfluoroalkyl substances (PFASs) are widely used due to their unique structure and excellent performance, while also posing threats on ecosystem, especially long-chain perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). As the control of conventional PFASs, fluoroalkylether substances (ether-PFASs) as alternatives are constantly emerging. Subsequently, the three representative ether-PFASs, chlorinated polyfluoroalkyl ether sulfonic acid (F-53B), hexafluoropropylene oxide-dimer acid (HFPO-DA), and 4,8-Dioxa-3H-perfluorononanoicacid (ADONA) are discovered and have received more attention in the environment and ecosystem. But their security is now also being challenged. This review systematically assesses their security from six dimensions including environmental occurrence in water, soil and atmosphere, as well as bioaccumulation and risk in plants, animals and humans. High substitution level is observed for F-53B, whether in environment or living things. Like PFOS or even more extreme, F-53B exhibits high biomagnification ability, transmission efficiency from maternal to infant, and various biological toxicity effects. HFPO-DA still has a relatively low substitution level for PFOA, but its use has emerged in Europe. Although it is less detected in human bodies and has a higher metabolic rate than PFOA, the strong migration ability of HFPO-DA in plants may pose dietary safety concerns for humans. Research on ADONA is limited, and currently, it is detected in Germany frequently while remaining at trace levels globally. Evidently, F-53B has shown increasing risk both in occurrence and toxicity compared to PFOS, and HFPO-DA is relatively safe based on available data. There are still knowledge gaps on security of alternatives that need to be addressed.

Per- and polyfluoroalkyl substance (PFAS) mixtures induce gut microbiota dysbiosis and metabolic disruption in silkworm (Bombyx mori L.)

Mixed legacy and emerging per- and polyfluoroalkyl substances (PFASs) are commonly found in soil and dust; however, the potential toxicity of PFAS mixtures (mPFASs) in insects is unknown. Using 16S rRNA gene sequencing and transcriptome sequencing (RNA-Seq), we evaluated the adverse effects of mPFASs on silkworms, a typical lepidopteran insect. After exposure to mPFASs, the silkworm midgut was enriched with high levels of PFASs, which induced histopathological changes. The composition of the midgut microbiota was significantly affected by mPFAS exposure, and functional predictions revealed significant disruption of some metabolic pathways. RNA-seq analysis revealed that mPFASs significantly changed the transcription profiles. Functional enrichment analysis of the differentially expressed genes also revealed that biological processes related to metabolic pathways and the digestive system were significantly affected, similar to the results of the gut microbiota analysis, suggesting that mPFAS exposure had an adverse effect on the metabolic function of silkworms and may further affect their normal growth. Finally, the significant correlation between abundance changes in the gut microbiota and metabolism/digestion-related genes further highlighted the role of the gut microbiota in mPFAS-related processes affecting the metabolic functions of silkworms. To our knowledge, this study is the first to evaluate the toxic effects of mPFASs in insects and provide basic data for further PFAS toxicity investigations in insects and comprehensive ecological risk assessments of mPFASs.

Tracing the Bioaccessibility of Per- and Polyfluoroalkyl Substances in Fish during Cooking Treatment

The effect of cooking on the contents of per- and polyfluoroalkyl substances (PFAS) in foods has been widely studied, but whether cooking-induced structural and chemical modifications in foods affect the oral bioaccessibility of PFAS remains largely unknown. In this study, three kinds of fishes with different fat contents were selected, and the bioaccessibility of PFAS during cooking treatment (steaming and frying) was evaluated using in vitro gastrointestinal simulation with gastric lipase addition. The results showed that related to their molecular structures, the bioaccessibility of an individual PFAS varied greatly, ranging from 26.0 to 108.1%. Cooking can reduce the bioaccessibility of PFAS, and steaming is more effective than oil-frying; one of the possible reasons for this result is that the PFAS is trapped in protein aggregates after heat treatment. Fish lipids and cooking oil ingested with meals exert different effects on the bioaccessibility of PFAS, which may be related to the state of the ingested lipid/oil and the degree of unsaturation of fatty acids. Gastric lipase boosted the release of long-chain PFAS during in vitro digestion, indicating that the degree of lipolysis considerably influences the bioaccessibility of hydrophobic PFAS. Estimated weekly PFAS intakes were recalibrated using bioaccessibility data, enabling more accurate and reliable dietary exposure assessments.

Comprehensive Assessment of Exposure Pathways for Perfluoroalkyl Ether Carboxylic Acids (PFECAs) in Residents Near a Fluorochemical Industrial Park: The Unanticipated Role of Cereal Consumption

With the replacement of perfluorooctanoic acid (PFOA) with perfluorinated ether carboxylic acids (PFECAs), residents living near fluorochemical industrial parks (FIPs) are exposed to various novel PFECAs. Despite expectations of low accumulation, short-chain PFECAs, such as perfluoro-2-methoxyacetic acid (PFMOAA), previously displayed a considerably high body burden, although the main exposure routes and health risks remain uncertain. Here, we explored the distribution of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in diverse environmental media surrounding a FIP in Shandong Province, China. PFECAs were found at elevated concentrations in all tested matrices, including vegetables, cereals, air, and dust. Among residents, 99.3% of the ∑36PFAS exposure, with a 43.9% contribution from PFECAs, was due to gastrointestinal uptake. Dermal and respiratory exposures were negligible at 0.1 and 0.6%, respectively. The estimated daily intake (EDI) of PFMOAA reached 114.0 ng/kg body weight (bw)/day, ranking first among all detected PFECAs. Cereals emerged as the dominant contributor to PFMOAA body burden, representing over 80% of the overall EDI. The median EDI of hexafluoropropylene oxide dimer acid (HFPO-DA) was 17.9 ng/kg bw/day, markedly higher than the USEPA reference doses (3.0 ng/kg bw/day). The absence of established threshold values for other PFECAs constrains a comprehensive risk assessment.

Legacy per- and polyfluoroalkyl substances (PFASs) especially alternative PFASs in shellfish from Shandong Province, China: Distribution, sources, and health risk

We investigated the distribution of 8 per- and polyfluoroalkyl substances (PFASs) in 321 shellfish samples collected from four coastal cities along the Yellow Sea and Bohai Sea of Shandong Province, China. The concentrations of total PFASs (∑PFASs) were in the range of 0.061-178.259 ng/g wet weight (ww). Two legacy long-chain compounds were dominant. Three emerging compounds and two short-chain alternatives were also observed with higher concentration and detection frequency than in previous studies, whereas 4, 8-dioxa-3H-perfluorononanoate acid (ADONA) was not detected. There were differences in concentrations and composition profiles of PFASs among different species, as well as among different sampling cities. According to scores of principal component analysis, metal plating plants, textile treatments, and fluoropolymer products were considered as the main sources of PFAS contamination in shellfish. Furthermore, a potential health risk of perfluorooctanoic acid should be highly considered for local residents that frequently consume crabs and molluscs.

Physical exercise and persistent organic pollutants

Exposure to the legacy and emerging persistent organic pollutants (POPs) incessantly has become an important threat to individual health, which is closely related to neurodevelopment, endocrine and cardiovascular homeostasis. Exercise, on the other hand, has been consistently shown to improve physical fitness. Whereas associations between traditional air pollutants, exercise and lung function have been thoroughly reviewed, reviews on associations between persistent organic pollutants and exercise are scarce. Hence, a literature review focused on exercise, exposure to POPs, and health risk assessment was performed for studies published from 2004 to 2022. The purpose of this review is to provide an overview of exposure pathways and levels of POPs during exercise, as well as the impact of exercise on health concerns attributable to the redistribution, metabolism, and excretion of POPs in vivo. Therein lies a broader array of exercise benefits, including insulin sensitizing, mitochondrial DNA repair, lipid metabolism and intestinal microecological balance. Physical exercise is conducive to reduce POPs body burden and resistant to health hazards of POPs generally. Besides, individual lipid metabolism condition is a critical factor in evaluating potential link in exercise, POPs and health effects.

Occurrences and fates of per- and polyfluoralkyl substances in textile dyeing wastewater along full-scale treatment processes

Industrial wastewater is a substantial source of per- and polyfluoroalkyl substances (PFASs) in the environment. However, very limited information is available on the occurrences and fates of PFASs along industrial wastewater treatment processes, particularly for the textile dyeing industry where PFASs occur extensively. Herein, the occurrences and fates of 27 legacy and emerging PFASs were investigated along the processes of three full-scale textile dyeing wastewater treatment plants (WWTPs) based on UHPLC-MS/MS in combination with self-developed solid extraction protocol featuring selective enrichment for ultrasensitive analysis. The total PFASs ranged at 630-4268 ng L-1 in influents, 436-755 ng L-1 in effluents, and 91.5-1182 μg kg-1 in the resultant sludge. PFAS species distribution varied among WWTPs, with one WWTP dominated by legacy perfluorocarboxylic acids while the other two dominated by emerging PFASs. Perfluorooctane sulfonate (PFOS) was trivial in the effluents from all the three WWTPs, indicating its diminished use in textile industry. Various emerging PFASs were detected at different abundances, demonstrating their use as alternatives to legacy PFASs. Most conventional processes of the WWTPs were inefficient in removing PFASs, especially for the legacy PFASs. The microbial processes could remove the emerging PFASs to different extents, whereas commonly elevated the concentrations of legacy PFASs. Over 90% of most PFASs could be removed by reverse osmosis (RO) and was enriched into the RO concentrate accordingly. The total oxidizable precursors (TOP) assay revealed that the total concentration of PFASs was increased by 2.3-4.1 times after oxidation, accompanied by formation of terminal perfluoroalkyl acids (PFAAs) and degradation of emerging alternatives to various extents. This study is believed to shed new light on the monitoring and management of PFASs in industries.

Novel perfluoroalkyl substances (PFAS) discovered in whole blood using automated non-targeted analysis of dried blood spots

A small subset of per- and polyfluoroalkyl substances (PFAS) are routinely screened in human blood. These compounds generally explain <50 % of the total PFAS in human blood. The percentage of known PFAS in human blood has been decreasing as replacement PFAS and more complex PFAS chemistries are introduced to the market. Most of these novel PFAS have not been previously identified. Non-targeted methods are required to characterize this "dark matter" PFAS. Our objective was to apply non-targeted PFAS analysis to human blood to gain an understanding about the sources, concentrations, and toxicity of these compounds. A high-resolution tandem mass spectrometry (HRMS) and software workflow for PFAS characterization in dried blood spots is reported. Dried blood spots are a less invasive collection technique compared to venous blood draws, allowing collection from vulnerable populations. Biorepositories of archived dried blood spots are available internationally from newborns and present opportunities to study prenatal exposure to PFAS. In this study, dried blood spot cards were analyzed using iterative MS/MS by liquid chromatography HRMS. Data processing was conducted using FluoroMatch Suite including a visualizer tool that presents homologous series, retention time vs m/z plots, MS/MS spectra, feature tables, annotations, and fragments for fragment screening. The researcher performing data-processing and annotation was blinded to the fact that standards were spiked in, and was able to annotate 95 % of standards spiked on dried blood spot samples, signifying a low false negative rate using FluoroMatch Suite. A total of 28 PFAS (20 standards and 4 exogenous compounds) were detected across five homologous series with Schymanski Level 2 confidence. Of these 4, 3 were perfluoroalkyl ether carboxylic acids (PFECA), a chemical class of PFAS which is increasingly being detected in environmental and biological matrices but is not currently screened in most targeted analysese. A further 86 potential PFAS were detected using fragment screening. PFAS are extremely persistent and widespread yet remain largely unregulated. Our findings will contribute to an improved an understanding of exposures. Application of these methods in environmental epidemiology studies have the potential to inform policy with regards to PFAS monitoring, regulation, and individual-level mitigation strategies.

Bioaccumulation, tissue distribution, and maternal transfer of novel PFOS alternatives (6:2 Cl-PFESA and OBS) in wild freshwater fish from Poyang Lake, China

As emerging alternatives to perfluorooctane sulfonate (PFOS), 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA) and sodium p-perfluorous nonenox-benzenesulfonate (OBS) were frequently detected in the four freshwater fish species collected from Poyang Lake. Median concentrations of 6:2 Cl-PFESA and OBS in fish tissues were 0.046-6.0 and 0.46-5.1 ng/g wet weight, respectively. The highest concentrations of 6:2 Cl-PFESA was found in fish livers, whereas OBS was found in the pancreas, brain, gonads, and skin. The tissue distribution pattern of 6:2 Cl-PFESA is similar to that of PFOS. The tissue/liver ratios of OBS were higher than those of PFOS, suggesting that OBS has a greater tendency to transfer from the liver to other tissues. The logarithmic bioaccumulation factors (log BAFs) of 6:2 Cl-PFESA in three carnivorous fish species were greater than 3.7, whereas those of OBS were less than 3.7, indicating that 6:2 Cl-PFESA had a strong bioaccumulation potential. Notably, sex- and tissue-specific bioaccumulation of OBS has also been observed in catfish. Most tissues (except the gonads) exhibited higher OBS concentrations in males than in females. However, no differences were found for 6:2 Cl-PFESA and PFOS. Maternal transfer efficiency of OBS was higher than that of 6:2 Cl-PFESA and PFOS in catfish (p < 0.05), indicating that OBS presents a higher risk of exposure to males and offspring through maternal offloading.

Per- and Polyfluoroalkyl Substances in Personal Hygiene Products: The Implications for Human Exposure and Emission to the Environment

Per- and polyfluoroalkyl substances (PFAS) have been related to reproductive toxicity in humans, but their occurrence in some specific personal hygiene products, i.e., sanitary pads, panty liners, tampons, paper diapers, menstrual cups, and bactericidal liquids, has not been extensively studied. This work investigated 31 representative PFAS in six categories of such personal hygiene products (n = 91). Perfluorinated carboxylic acids were the primary PFAS found in the samples, accounting for over 85% of the total concentrations of PFAS. Paper diapers contained the highest sum of PFAS concentrations (64.6 ng/g) followed by sanitary pads (52.3 ng/g) and menstrual cups (21.1 ng/g). The estimated exposure doses of perfluorooctanoic acid through dermal absorption from the use of menstrual cups and paper diapers for infants (adults) were 0.77 and 2.1 (1.2) ng/kg-bw/day, which contributed more than normal dust ingestion. The estimated emission of paper diapers and sanitary pads into the environment was 2.58 and 322 kg/year with an assumed leaching rate of 100%. The potential exposure of PFAS through the use of personal hygiene products observed in this work suggests a previously unreported exposure pathway of these chemicals to humans.

Large-scale assessment of exposure to legacy and emerging per- and polyfluoroalkyl substances in China's shorebirds

Emerging per- and polyfluoroalkyl substances (PFAS) have become more widely applied, whereas legacy PFAS such as PFOS continue to distribute ubiquitously in the environment. Large-scale assessment of wildlife exposure to both emerging and legacy PFAS plays a key role in effective biomonitoring to better discriminate regional contamination patterns and provide early warnings. Using eggs of two closely-related shorebird species collected across China during the breeding season in 2021, we constructed contrasting PFAS levels and profiles in coastal versus inland populations. The highest ∑PFAS concentrations were found in two Kentish plover (Charadrius alexandrinus) populations from the Bohai Sea, a semi-enclosed shallow bay located in northeast China. These two populations showed exceptionally high PFOA concentrations (mean: 94 and 121 ng/g wet weight; West and North Bohai Sea, respectively) dominating the overall PFAS profile (66% for both). This pattern is characteristic, compared to that of other seabird eggs worldwide. By comparison, PFAS profile in the white-faced plover (Charadrius dealbatus) population at the South China Sea coast was dominated by PFOS (46%), which showed similar levels to those at the North Bohai Sea coast (mean: 29 and 20 ng/g, respectively). PFAS concentrations of Kentish plovers from the remote Qinghai Lake were lower compared to the three coastal populations, and were dominated by PFNA (mean: 2.6 ng/g, 29%) and PFOS (mean: 2.5 ng/g, 27%). None of the eggs analyzed in the present study exceeded estimated toxicity reference values for PFOS or PFOA. Additionally, the emerging 6:2 Cl-PFESA was detected in eggs from all regions, while its concentrations were highest in the Bohai Sea populations, and short-chain PFBS was only detected in the North Bohai Sea population. Our results indicate intensive local emissions of PFOA and emerging PFAS at the Bohai Sea region, and warrant further investigation and monitoring.

Human health risk assessment of 6:2 Cl-PFESA through quantitative in vitro to in vivo extrapolation by integrating cell-based assays, an epigenetic key event, and physiologically based pharmacokinetic modeling

Human health risk assessment of chemicals is essential but often relies on time-consuming and animal and labor-extensive procedures. Here, we develop a population-based, quantitative in vitro to in vivo extrapolation (QIVIVE) approach which depended on cellular effects monitored by in vitro assays, considered chemical internal concentration determined by LC-MS/MS, extrapolated into in vivo target tissue concentration through physiologically based pharmacokinetic (PBPK) modelling, and assessed populational health risk using in silico modelling. By applying this QIVIVE approach to 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), as a representative of the emerging pollutants, we find that 6:2 Cl-PFESA disturbed lipid homeostasis in HepG2 cells through enhancement of lipid accumulation and fatty acid β-oxidation, during which miR-93-5p served as a key event towards toxicity and thus, could serve as an efficient toxicity marker for risk assessment; further, the disruption potency of lipid homeostasis of 6:2 Cl-PFESA for the most of studied populations in China might be of moderate concern. Together, our approach improved the reliability of QIVIVE during human health risk assessment, which can readily be used for other chemicals.

Perfluoroalkyl and polyfluoroalkyl substances in cord serum of newborns and their potential factors

The demonstrated developmental and reproductive toxicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), coupled with the increasing production and use of emerging per- and polyfluoroalkyl substances (PFASs) has resulted in progressively higher human exposure levels. This has raised concerns about PFAS exposure levels in the fetus, which is highly susceptible to the potential effects of hazardous environmental chemicals. However, in utero exposure to PFASs and health implications have not been fully characterized in China. To fill this gap, we analyzed 19 PFASs in umbilical cord serum samples (n = 66). Information about the mothers and newborns was obtained through questionnaires. Associations between maternal characteristics and neonatal birth weight and PFAS concentrations were analyzed using nonparametric tests. As results, PFOA was detected in all serum samples. The highest median concentration of PFOS in umbilical serum was 1.092 ng·mL^-1, followed by perfluoropentanoic acid (median: 0.633 ng·mL^-1). Trifluroacetic acid and perfluoropropanoic acid were detected in cord serum for the first time, and their median concentrations were 0.229 and 0.266 ng·mL^-1, respectively. Neonatal birth weight was negatively correlated with long-chain PFOS (r = -0.319, P < 0.05), and the concentrations of perfluoroundecanoic acid and perfluorododecanoic acid were significantly different between the birth weight groups. Maternal age, maternal education, diet, and nutritional supplementation during pregnancy can all affect umbilical serum exposure to PFASs. These results demonstrate that legacy PFASs remain major contributors to the composition of human PFASs, while the concentration levels of emerging short-chain alternatives have increased significantly. Modifying the mother's diet may reduce the risk of intrauterine PFAS exposure. Special attention to exposure to highly novel PFASs and confirmation of potential determinants should be taken as a priority in the plan for risk management and actions in this area.

Sex-specific associations between legacy and novel per- and polyfluoroalkyl substances and telomere length in newborns in Wuhan, China: Mixture and single pollutant associations

Telomere length (TL) at birth predicts later life TL and is related to health. Prenatal exposure to environmental pollutants might affect TL, but the associations between intrauterine per- and polyfluoroalkyl substances (PFASs) exposure and neonatal TL remained inconclusive. This study aimed to explore the single pollutant and mixture associations between legacy and novel PFASs and TL in newborns. In 908 mother-newborn pairs from Wuhan, China, thirteen PFASs were measured in cord serum, and TL was determined in cord leukocytes. Weighted quantile sum (WQS) regression and generalized linear model (GLM) were utilized to analyze the associations between PFASs mixture and single PFASs and TL in newborns. Furthermore, stratified and interaction analyses were performed to evaluate if there were sex-specific associations. The concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) ranked the highest (geometric mean, 4.12, 1.61, and 0.77 ng/mL, respectively) among the 13 measured PFASs. Each unit increase in WQS index of PFASs mixture was associated with -5.19 % change (95% CI, -9.44, -0.73) of neonatal TL, and 8:2 Cl-PFESA contributed most (32.59 %) to the mixture association. In stratified analyses by neonatal sex, PFOS (-4.73 % change, 95% CI, -8.40, -0.93 for per doubling concentration) and 8:2 Cl-PFESA (-4.52 % change, 95% CI, -8.20, -0.70) were negatively associated with neonatal TL in male newborns, but no significant association appeared in females. In summary, intrauterine exposure to PFASs in mixture was associated with shorter neonatal TL, and the negative associations of 8:2 Cl-PFESA and PFOS with neonatal TL were observed only in boys. Future risk assessments are needed to pay more attention to the health effects of novel PFASs.

Integration of metabolomics and proteomics reveals the underlying hepatotoxic mechanism of perfluorooctane sulfonate (PFOS) and 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA) in primary human hepatocytes

Perfluorooctane sulfonate (PFOS) and its alternative 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) are ubiquitous in various environmental and human samples. They have been reported to have hepatotoxicity effects, but the potential mechanisms remain unclear. Herein, we integrated metabolomics and proteomics analysis to investigate the altered profiles in metabolite and protein levels in primary human hepatocytes (PHH) exposed to 6:2 Cl-PFESA and PFOS at human exposure relevant concentrations. Our results showed that 6:2 Cl-PFESA exhibited higher perturbation effects on cell viability, metabolome and proteome than PFOS. Integration of metabolomics and proteomics revealed that the alteration of glycerophospholipid metabolism was the critical pathway of 6:2 Cl-PFESA and PFOS-induced lipid metabolism disorder in primary human hepatocytes. Interestingly, 6:2 Cl-PFESA-induced cellular metabolic process disorder was associated with the cellular membrane-bounded signaling pathway, while PFOS was associated with the intracellular transport process. Moreover, the disruption effects of 6:2 Cl-PFESA were also involved in inositol phosphate metabolism and phosphatidylinositol signaling system. Overall, this study provided comprehensive insights into the hepatic lipid toxicity mechanisms of 6:2 Cl-PFESA and PFOS in human primary hepatocytes.

Per-/polyfluoroalkyl substance concentrations in human serum and their associations with immune markers of rheumatoid arthritis

Per-/polyfluoroalkyl substances (PFASs) are ubiquitous in the environment and have been proved to be immunotoxic to humans. However, it remains unclear whether exposure to PFASs affects the risk of rheumatoid arthritis (RA). In this study, nine PFASs were determined in human serum collected from 280 health populations and 294 RA patients in a cohort enrolled between 2018 and 2020 in Hangzhou, China, and were examined their correlations with immune marker levels. Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) were the predominant PFASs in human serum, with median (mean) concentrations of 5.4 (7.6), 2.8 (3.5), and 1.9 (2.5) ng/mL, respectively. Serum PFOA and 6:2 Cl-PFESA concentrations were positively correlated with anti-cyclic citrullinated peptide antibody (ACPA) (β_PFOA = 0.59, 95% confidence interval (CI): 0.37, 0.81; β_{6:2 Cl-PFESA} = 0.48, 95% CI: 0.29, 0.66), immunoglobulin G (β_PFOA = 0.25, 95% CI: 0.21, 0.29; β_{6:2 Cl-PFESA} = 0.16, 95% CI: 0.12, 0.19) as well as rheumatoid factors (RF) (β_PFOA = 0.57, 95% CI: 0.34, 0.80; β_{6:2 Cl-PFESA} = 0.54, 95% CI: 0.36, 0.72). The correlations between serum PFOS levels and RF (β = 0.52, 95% CI: 0.28, 0.77), ACPA (β = 0.48, 95% CI: 0.23, 0.73), as well as immunoglobulin M (β = -0.24, 95% CI: 0.64, 0.15) respectively were statistically stronger. We also found PFOA concentrations in serum were associated with the level of C-reactive protein (β = 0.52, 95% CI: 0.40, 0.65). To our knowledge, this is the first study reporting significant associations between several PFASs and change of specific immune marker levels, suggesting that PFAS exposure may increase the risk of RA in adults.

Emissions, Isomer-Specific Environmental Behavior, and Transformation of OBS from One Major Fluorochemical Manufacturing Facility in China

Sodium p-perfluorous nonenoxybenzenesulfonate (OBS), a novel alternative to perfluorooctane sulfonic acid (PFOS), has been widely used in various fields in China and has certain toxic effects similar to PFOS. This study monitored OBS and 15 legacy PFASs in surface water, sediment, soil, and crucian carp near a fluorochemical manufacturing factory (FMF) in Suqian, China, focusing on the emission, isomer-specific environmental fate, and transformation of OBS. One to four orders of magnitude higher concentrations of OBS than other polyfluoroalkyl substances (PFASs) in all samples indicate that industrial emission is an important point source of OBS in the surrounding environment. The concentrations of OBS in surface water, sediment, and soil decreased exponentially as the distance from the FMF increases. The proportions of OBS-c, the dominant isomer, increased in the order: water (75.5 ± 6.4%), sediment (85.7 ± 10%), fish (muscle: 94.1 ± 0.99%; blood: 93.5 ± 1.4%), suggesting its preferential accumulation in sediment and fish than other isomers. Mono-hydroxylated transformation products of OBS were first identified in water, sediment, and fish, suggesting its hydroxylation may exist in the real environment. The transformation of OBS may explain its significantly lower bioaccumulation than PFOS in fish. However, considering the higher BAF of OBS than the regulatory bioaccumulation criterion and the possible stronger toxicity of its transformation products, further studies on its bioaccumulation and transformation are warranted.

Occurrence, Distribution, and Human Exposure of Emerging Liquid Crystal Monomers (LCMs) in Indoor and Outdoor Dust: A Nationwide Study

Liquid crystal monomers (LCMs) are a class of emerging, persistent, bioaccumulative, and toxic organic pollutants. They are detected in various environmental matrixes that are associated with electronic waste (e-waste) dismantling. However, their occurrence and distribution in indoor and outdoor dust on a national scale remain unknown. In this study, a dedicated target analysis quantified a broad range of 60 LCMs in dust samples collected across China. The LCMs were frequently detected in indoor (n = 48) and outdoor dust (n = 97; 37 sampled concomitantly with indoors dust) from dwellings, and indoor dust from cybercafés (n = 34) and phone repair stores (n = 22), with median concentrations of 41.6, 94.7, 106, and 171 ng/g, respectively. No significant spatial difference was observed for the concentrations of the total LCMs among distinct geographical regions (p > 0.05). The median daily intake values of the total LCMs via dust ingestion, dermal contact, and inhalation were estimated at 1.50 × 10^-2, 2.90 × 10^-2, and 8.57 × 10^-6 ng/kg BW/day for adults and 1.47 × 10^-1, 1.22 × 10^-1, and 2.18 × 10^-5 ng/kg BW/day for children, respectively. These estimates suggested higher exposure risks for children and indicated that dust ingestion and dermal contact significantly contribute to the human intake of LCMs. The microenvironmental pollution levels of LCMs together with the potential exposure risks associated with some of these chemicals are of concern for human health.

Multiple pollutants in groundwater near an abandoned Chinese fluorine chemical park: concentrations, correlations and health risk assessments

Contamination and adverse effects from various pollutants often appear in abandoned industrial regions. Thus, nine groundwater samples were collected from the vicinity of the fluorochemical industry in Fuxin City, Liaoning Province, to determine concentrations of the ten heavy metals arsenic (As), chromium (Cr), cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu), manganese (Mn), zinc (Zn), iron (Fe) and mercury(Hg), as well as those of fluorine (F⁻) and eighteen poly- and perfluorinated substances (PFASs), analyse correlation relationships, and assess the health risks for different age groups. The results showed that the levels of fluorine (F⁻) (0.92–4.42 mg·L⁻¹), Mn (0.0005–4.91 mg·L⁻¹) and Fe (1.45–5.61 mg·L⁻¹) exceeded the standard limits for drinking water. Short chain perfluorobutanoic acid (PFBA) (4.14–2501.42 ng·L⁻¹), perfluorobutane sulfonate (PFBS) (17.07–51,818.61 ng·L⁻¹) and perfluorohexanoic acid (PFHxA) (0.47–936.32 ng·L⁻¹) were the predominant substances from the PFASs group. No individual PFASs levels had significant relationships with F⁻ or heavy metal contents. There was a positive relationship between short chain PFASs concentrations and water depth and a negative relationship between long chain PFASs concentration and water depth. The hazard quotient (HQ) decreased in the order F⁻ > heavy metals > PFASs and also decreased for older age groups. In addition, As, Fe, Mn and perfluorooctanoic acid (PFOA) were the main sources of risk from the heavy metal and PFASs groups, respectively.

Perfluoroalkyl substances are linked to incident chronic spontaneous urticaria: A nested case-control study

Previous studies suggested immunotoxicity of perfluoroalkyl substances (PFASs), but contradictory findings were reported for the associations of PFASs with allergies. The current study aimed to investigate the association of serum PFASs with incident chronic spontaneous urticaria (CSU) in adults. A nested case-control study within a longitudinal cohort of 7051 government employees in China was conducted. Participants with urticaria at the baseline were excluded. During the first follow-up, 70 incident CSU cases were included, and 70 matched healthy controls were randomly selected. In serum samples collected at the baseline, eight PFASs were determined using the UHPLC-MS/MS approach. The median serum concentrations of perfluorobutanoic acid (PFBA) and perfluoroheptanoic acid (PFHpA) were significantly higher in participants with incident CSU. The area under the receiver operating characteristic curve was 0.714 (95% CI: 0.60-0.83) based on the joint prediction by PFBA and PFHpA. The Bayesian kernel machine regression showed a nonlinear positive overall effect of the mixture of PFASs, and identified significant single effects of PFBA and PFHpA. Serum interleukin-4 was significantly higher in the case group at baseline, and was positively associated with PFHpA (r = 0.24). Causal mediation analysis indicated interleukin-4 as a partial mediator (14.8%) in the association of PFHpA with CSU. In conclusion, serum PFASs are associated with an increased risk of incident CSU, and PFBA and PFHpA might be the effective compounds.