Perfluorinated compounds: emerging POPs with potential immunotoxicity

Desorption of Polycyclic Aromatic Hydrocarbons from Microplastics in Human Gastrointestinal Fluid Simulants-Implications for Exposure Assessment

Microplastics have been detected in various food types, suggesting inevitable human exposure. A major fraction may originate from aerial deposition and could be contaminated by ubiquitous pollutants such as polycyclic aromatic hydrocarbons (PAHs). While data on the sorption of pollutants to microplastics are abundant, the subsequent desorption in the gastrointestinal tract (GIT) is less understood. This prompted us to systematically investigate the release of microplastics-sorbed PAHs at realistic loadings (44-95 ng/mg) utilizing a physiology-based in vitro model comprising digestion in simulated saliva, gastric, and small and large intestinal fluids. Using benzo[a]pyrene as a representative PAH, desorption from different microplastics based on low density polyethylene (LDPE), thermoplastic polyurethanes (TPUs), and polyamides (PAs) was investigated consecutively in all four GIT fluid simulants. The cumulative relative desorption (CRD) of benzo[a]pyrene was negligible in saliva simulant but increased from gastric (4 ± 1% - 15 ± 4%) to large intestinal fluid simulant (21 ± 1% - 29 ± 6%), depending on the polymer type. CRDs were comparable for ten different microplastics in the small intestinal fluid simulant, except for a polydisperse PA-6 variant (1-10 μm), which showed an exceptionally high release (51 ± 8%). Nevertheless, the estimated contribution of microplastics-sorbed PAHs to total human PAH dietary intake was very low (≤0.1%). Our study provides a systematic data set on the desorption of PAHs from microplastics in GIT fluid simulants.

Occurrence of COVID-19 and serum per- and polyfluoroalkyl substances: A case-control study among workers with a wide range of exposures

Per- and polyfluoroalkyl substances (PFAS) are a broad class of synthetic chemicals; some are present in most humans in developed countries. Some studies suggest that certain PFAS may have immunotoxic effects in humans, which could put individuals with high levels of exposure at increased risk for infectious diseases such as COVID-19. We conducted a case-control study to examine the association between COVID-19 diagnosis and PFAS serum concentrations among employees and retirees from two 3 M facilities, one of which historically generated perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS). Participants completed enrollment and follow-up study visits in the Spring of 2021. Participants were categorized as cases if they reported a COVID-19 diagnosis or became sick with at least one symptom of COVID-19 when someone else in their household was diagnosed, otherwise they were categorized as a control. COVID-19 diagnosis was modeled in relation to concentration of serum PFAS measured at enrollment after adjusting for covariates. The analytic sample comprised 573 individuals, 111 cases (19.4%) and 462 controls (80.6%). In adjusted models, the odds ratio of COVID-19 was 0.94 per interquartile range (14.3 ng/mL) increase in PFOS (95% confidence interval 0.85, 1.04). Results for PFOA, PFHxS, and perfluorononanoic acid (PFNA) were similar. Other PFAS present at lower concentrations were examined as categorical variables (above the limit of quantification [LOQ], yes vs. no [referent category]), and also showed no positive associations. In our study, which used individual-level data and included people with high occupational exposure, the serum concentrations of all PFAS examined were not associated with an increased odds ratio for COVID-19. At this point, the epidemiologic data supporting no association of COVID-19 occurrence with PFAS exposure are stronger than those suggesting a positive association.

Evaluating aliphatic CF, CF2, and CF3 groups as vibrational Stark effect reporters

Given the extensive use of fluorination in molecular design, it is imperative to understand the solvation properties of fluorinated compounds and the impact of the C-F bond on electrostatic interactions. Vibrational spectroscopy can provide direct insights into these interactions by using the C-F bond stretching [v(C-F)] as an electric field probe through the vibrational Stark effect (VSE). In this work, we explore the VSE of the three basic patterns of aliphatic fluorination, i.e., mono-, di-, and trifluorination in CF, CF2, and CF3 groups, respectively, and compare their response to the well-studied aromatic v(C-F). Magnitudes (i.e., Stark tuning rates) and orientations of the difference dipole vectors of the v(C-F)-containing normal modes were determined using density functional theory and a molecular dynamics (MD)-assisted solvatochromic analysis of model compounds in solvents of varying polarity. We obtain Stark tuning rates of 0.2-0.8 cm-1/(MV/cm), with smallest and largest electric field sensitivities for CFaliphatic and CF3,aliphatic, respectively. While average electric fields of solvation were oriented along the main symmetry axis of the CFn, and thus along its static dipole, the Stark tuning rate vectors were tilted by up to 87° potentially enabling to map electrostatics in multiple dimensions. We discuss the influence of conformational heterogeneity on spectral shifts and point out the importance of multipolar and/or polarizable MD force fields to describe the electrostatics of fluorinated molecules. The implications of this work are of direct relevance for studies of fluorinated molecules as found in pharmaceuticals, fluorinated peptides, and proteins.

Implications of Prenatal Exposure to Endocrine-Disrupting Chemicals in Offspring Development: A Narrative Review

During the last decades, endocrine-disrupting chemicals (EDCs) have attracted the attention of the scientific community, as a result of a deepened understanding of their effects on human health. These compounds, which can reach populations through the food chain and a number of daily life products, are known to modify the activity of the endocrine system. Regarding vulnerable groups like pregnant mothers, the potential damage they can cause increases their importance, since it is the health of two lives that is at risk. EDCs can affect the gestation process, altering fetal development, and eventually inducing the appearance of many disorders in their childhood and/or adulthood. Because of this, several of these substances have been studied to clarify the influence of their prenatal exposure on the cognitive and psychomotor development of the newborn, together with the appearance of non-communicable diseases and other disorders. The most novel research on the subject has been gathered in this narrative review, with the aim of clarifying the current knowledge on the subject. EDCs have shown, through different studies involving both animal and human investigation, a detrimental effect on the development of children exposed to the during pregnancy, sometimes with sex-specific outcomes. However, some other studies have failed to find these associations, which highlights the need for deeper and more rigorous research, that will provide an even more solid foundation for the establishment of policies against the extended use of these chemicals.

Association between prenatal perfluorinated compounds exposure and risk of pregnancy complications: A meta-analysis

BACKGROUND AND OBJECTIVE

Per- and polyfluoroalkyl substances (PFASs) have been shown to be persistent and bioaccumulative. An elevated danger of pregnancy complications perhaps connected with exposure to PFASs, but the potential effects remain elusive. The objective of this study is to investigate the possible association between PFASs exposure and pregnancy complications, drawing upon existing evidence.

METHODS

Electronic databases of PubMed, Qvid Medline, Embase, and Web of Science were searched thoroughly to identify eligible research published prior to November 28, 2023, examining the relationship between PFASs and pregnancy-related complications. To evaluate the quality of observational studies incorporated into the article, the Strengthening Reporting of Observational Studies in Epidemiology (STROBE) tool was utilized. The main outcomes assessed in this study included gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy (HDP), gestational hypertension (GH), and preeclampsia (PE).

RESULTS

Twenty-five relevant studies involving 30079 participants were finally selected from four databases. The combined estimates indicate that prenatal exposure to perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), and perfluoroenanthic acid (PFHpA) is associated with gestational diabetes mellitus (GDM) (PFOA: OR = 1.45, 95%CI: 1.07-1.94, P = 0.015; PFHxS: OR = 1.16, 95%CI: 1.00-1.36, P = 0.055; PFBS: OR = 1.44, 95%CI: 1.16-1.79, P = 0.001; PFHpA: OR = 1.41, 95%CI: 1.10-1.82, P = 0.008). The exposure to PFBS is positively associated with HDP (OR = 1.27, 95%CI: 1.14-1.41, P < 0.001), while both PFOA and PFHpA demonstrate statistically significant positive correlations with GH (PFOA: OR = 1.09, 95%CI: 1.00-1.19, P = 0.049; PFHpA: OR = 1.43, 95%CI: 1.15-1.78, P = 0.001). Negative correlations were observed for prenatal perfluorododecanoic acid (PFDoA) exposure and GH (OR = 0.71, 95%CI: 0.57-0.87, P = 0.001). However, no compelling evidence was identified to link PFASs exposure with the risk of PE.

CONCLUSION

According to the meta-analysis findings, exposure to PFASs may be linked to GDM, HDP, and GH, but it does not significantly raise the risk of PE alone. Further research with larger sample size is required to verify this potential association and explore the biological mechanisms.

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

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

Photodegradation and photocatalysis of per- and polyfluoroalkyl substances (PFAS): A review of recent progress

Per- and polyfluoroalkyl substances (PFAS) are oxidatively recalcitrant organic synthetic compounds. PFAS are an exceptional group of chemicals that have significant physical characteristics due to the presence of the most electronegative element (i.e., fluorine). PFAS persist in the environment, bioaccumulate, and have been linked to toxicological impacts. Epidemiological and toxicity studies have shown that PFAS pose environmental and health risks, requiring their complete elimination from the environment. Various separation technologies, including adsorption with activated carbon or ion exchange resin; nanofiltration; reverse osmosis; and destruction methods (e.g., sonolysis, thermally induced reduction, and photocatalytic dissociation) have been evaluated to remove PFAS from drinking water supplies. In this review, we will comprehensively summarize previous reports on the photodegradation of PFAS with a special focus on photocatalysis. Additionally, challenges associated with these approaches along with perspectives on the state-of-the-art approaches will be discussed. Finally, the photocatalytic defluorination mechanism of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) following complete mineralization will also be examined in detail.

Associations between prenatal exposure to per- and polyfluoroalkyl substances and wheezing and asthma symptoms in 4-year-old children: The Japan Environment and Children's Study

The effects of early-life exposure to per- and polyfluoroalkyl substances (PFAS) on the onset of asthma in children have been unclear. We examined the association between prenatal PFAS exposure and wheezing and asthma symptoms among 4-year-old children in a total of 17,856 mother-child pairs from the Japan Environment and Children's Study. Maternal first-trimester serum concentrations of six PFAS were used for the exposure assessment. We defined "wheeze ever," "current wheeze," "current symptoms of severe asthma," and "asthma ever" at the age of 4 years by the responses to the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and "doctor-diagnosed asthma" by the response to a corresponding question. Multivariate logistic regression models were used to examine exposure-outcome associations. Our findings revealed that doubling of the PFOA concentration was associated with a reduced occurrence of "wheeze ever," yielding an adjusted odds ratio of 0.94 (95% CI: 0.90-0.98). Also, doubling in the concentrations of PFOA and PFHxS was associated with a decreased prevalence of "asthma ever," with adjusted odds ratios of 0.94 (95% CI: 0.88-1.00) and 0.95 (95% CI: 0.90-0.99), respectively. However, these associations were not significant after applying the Bonferroni correction. The estimated exposure-response curves were nearly linear with a subtle or flat slope. When stratified by the child's sex or the mother's history of asthma, most of the estimated confidence intervals were overlapped between each pair of strata. Regional stratification analysis indicated low-to-moderate heterogeneity in 12 exposure-outcome pairs and moderate-to-high heterogeneity in 9 out of the 30 examined pairs. This study found no clear associations between prenatal PFAS exposure and the prevalence of wheezing and asthma among children at the age of 4 years.

Occurrence of metals, phthalate esters, and perfluoroalkyl substances in cellar water and their relationship with bacterial community in rural areas of China

Water cellars are traditional rainwater harvesting facilities that have been widely used in rural areas of northwest China. However, there are few reports about the water quality and health risk caused by the cellar water, especially phthalate esters (PAEs) and perfluoroalkyl substances (PFASs). This study investigated and assessed the health risks caused by the metals, PAEs, PFASs and bacterial communities in cellar water. The results showed that the turbidity and total number of bacterial colonies ranged from 4.7 to 58.5 NTU and 5-557 CFU/mL, respectively. The turbidity and total number of bacterial colonies were the main water quality problems. Due to high concentration of Tl (0.005-0.171 μg/L), the samples reached a high level of metal pollution. PAEs showed no non-carcinogenic and carcinogenic risk. The perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) were the main components of PFASs. PFOA and PFOS reached a moderate risk level in many cellar water samples. Moreover, Tl, Pb, As, PFBA and PFBS could change the bacterial community composition and induce the enrichment of bacterial functions related to human diseases. Besides these parameters, dissolved oxygen (DO) also affected the bacterial functions related to human diseases. Therefore, more attention should be paid to turbidity, DO, Tl, Pb, As, PFOA, PFOS, PFBA and PFBS in the cellar water. These results are meaningful for the water quality guarantee and health protection in rural areas of China.

Accumulation and dietary risks of perfluoroalkyl substances in fish and shellfish: A market-based study in Barcelona

Since the 1940s, per- and polyfluoroalkyl substances (PFAS) have been widely produced and used in various applications due to their unique properties. Consequently, the principal exposure routes of PFAS have been broadly studied, leading to the conclusion that dietary exposure (more specifically, the consumption of fish and seafood) was one of their main contributors. Thus, developing an analytical method that determines the level of PFAS in fish and seafood has become a relevant subject. In this work, a previous analytical method has been optimized to determine 12 PFAS in fish muscle from salmon, tuna, cod, hake, sardine, anchovy, and sole, as well as in seven different seafood species (i.e., cuttlefish, octopus, squid, shrimp, Norway lobster, prawn, and mussel) by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Subsequently, the PFAS profile of the different species was studied to determine if it was consistent with that previously reviewed in the literature and to know the most relevant contribution of PFAS for each species. Finally, human exposure to PFAS through their consumption was estimated by the daily intake for seven different age/gender groups. PFAS were obtained from 0.014 to 0.818 ng g-1 wet weight in fish samples. Sardines, anchovies, and soles presented the highest PFAS levels. However, cod samples also showed some PFAS traces. Regarding seafood, PFAS levels range from 0.03 to 36.7 ng g-1 dry weight for the studied species. A higher concentration of PFAS has been found in the cephalopods' spleens and the crustaceans' heads. PFOS and PFBS were the predominant compounds in each seafood species, respectively. On the other hand, in the case of mussels, which are the less polluted species of the study, contamination by longer-chained PFAS was also observed. Finally, the total intake of PFAS due to fish and shellfish consumption for the Spanish adult population was estimated at 17.82 ng day-1. Nevertheless, none of the analyzed samples exceeded the European Food Safety Authority (EFSA) risk value for the supervised PFAS in any age/gender group reviewed.

The Role of Endocrine Disrupting Chemicals in Gestation and Pregnancy Outcomes

Endocrine disrupting chemicals (EDCs) are exogenous substances widely disseminated both in the environment and in daily-life products which can interfere with the regulation and function of the endocrine system. These substances have gradually entered the food chain, being frequently found in human blood and urine samples. This becomes a particularly serious issue when they reach vulnerable populations such as pregnant women, whose hormones are more unstable and vulnerable to EDCs. The proper formation and activity of the placenta, and therefore embryonic development, may get seriously affected by the presence of these chemicals, augmenting the risk of several pregnancy complications, including intrauterine growth restriction, preterm birth, preeclampsia, and gestational diabetes mellitus, among others. Additionally, some of them also exert a detrimental impact on fertility, thus hindering the reproductive process from the beginning. In several cases, EDCs even induce cross-generational effects, inherited by future generations through epigenetic mechanisms. These are the reasons why a proper understanding of the reproductive and gestational alterations derived from these substances is needed, along with efforts to establish regulations and preventive measures in order to avoid exposition (especially during this particular stage of life).

Nationwide distribution of per- and polyfluoroalkyl substances (PFAS) in road dust from India

In India, information on the occurrence and distribution of legacy and emerging per- and polyfluoroalkyl substances (PFAS) is deficient. In the present study, nationwide 79 road dust samples were collected from 12 states and 1 union territory for the analysis of 34 PFAS. Overall, total concentrations of 21 quantified PFAS (∑21PFAS) ranged 23-861 pg/g (median: 116 pg/g), with perfluorooctane sulfonic acid (PFOS) being predominant (median: 19.9 pg/g). Short to long chain perfluoroalkyl carboxylic acids (PFCAs; C4 - C18) were detected, where the concentrations of PFAS decreased with the increase in PFAS carbon chain length. ∑21PFAS was highest in road dust from urban area (n = 27; median: 230 pg/g), followed by suburban (n = 21; median: 126 pg/g) and rural areas (n = 31; median: 76 pg/g), suggesting environmental impacts of industriallization and urbanization on PFAS distribution. PFAS composition in rural road dust was significantly different from those in suburban and urban samples (p < 0.01). Regarding 4 geographical regions of India, PFAS in road dust showed spatial difference where higher concentrations were found in South India compared to other regions. ∑21PFAS were positively associated with city-wise population of India (rs = 0.40, p < 0.01). Strong to moderate positive correlation was observed between ∑21PFAS, fluorotelomer sulfonic acids, and PFCAs (rs = 0.23, 0.30, and 0.28, respectively; p < 0.05) and the total state-wise vehicles in India, suggesting that vehicles exhaust or non-exhaust (e.g., vehicle tire debris and polishing material) might contribute to the PFAS occurrence in Indian road dust. Toddlers (2-5 years) had the highest estimated daily intake of ∑PFAS via road dust ingestion under average-case and worst-case scenarios (0.55 and 1.16 pg/kg bw/day, respectively). This is the first time to evaluate PFAS in Indian road dust nationwide, aiding to provide first-hand data for human exposure to PFAS in India.

Impact of per- and polyfluorinated alkyl substances (PFAS) on the marine environment: Raising awareness, challenges, legislation, and mitigation approaches under the One Health concept

Per- and polyfluorinated alkyl substances (PFAS) have long been known for their detrimental effects on the ecosystems and living organisms; however the long-term impact on the marine environment is still insufficiently recognized. Based on PFAS persistence and bioaccumulation in the complex marine food network, adverse effects will be exacerbated by global processes such as climate change and synergies with other pollutants, like microplastics. The range of fluorochemicals currently included in the PFAS umbrella has significantly expanded due to the updated OECD definition, raising new concerns about their poorly understood dynamics and negative effects on the ocean wildlife and human health. Mitigation challenges and approaches, including biodegradation and currently studied materials for PFAS environmental removal are proposed here, highlighting the importance of ongoing monitoring and bridging research gaps. The PFAS EU regulations, good practices and legal frameworks are discussed, with emphasis on recommendations for improving marine ecosystem management.

Temporal variation of per- and polyfluoroalkyl substances (PFASs) abundances in Shenzhen Bay sediments over past 65 years

We examined the vertical distribution of per- and polyfluoroalkyl substances (PFASs) and total organic carbon in sediment cores located in Shenzhen Bay area. We investigated the 210Pbex specific activity of the sediments and calculated the flux of PFASs to understand the temporal variation of PFASs in the past 65 years. The results showed that the concentrations of PFASs generally decreased with depth, ranging from 13 to 251 pg/g dw. The highest PFASs detected were perfluorobutanesulfonic acid, perfluorooctanoic acid, and perfluorohexanoic acid, which correspond to raw materials used in fire-fighting foam and food packaging industries. The flux of PFASs in Shenzhen Bay showed varying growth after 1978 when China's GDP entered a rapid growth stage. Our findings suggest that the vertical distribution of PFASs in Shenzhen Bay is fluctuating with the changes in industrial types and economic development, with implications for studying the fate of other persistent pollutants in the oceans.

Advancement in utilization of bio-based materials including cellulose, lignin, chitosan for bio-inspired surface coatings with special wetting behavior: A review on fabrication and applications

Natural bio-material surface with hydrophobic behavior (aqueous droplet to roll off from its surface) has inspired researchers to design sustainable artificial coatings with hydrophobic or superhydrophobic behavior. The developed hydrophobic or superhydrophobic artificial coatings are highly useful in various applications such as water remediation, oil/water separation, self-cleaning, anti-fouling, anti-corrosion and also in medical fields including anti-viral, anti-bacterial efficacy. In recent years, among various coating materials, bio-based materials derived from plants and animals (cellulose, lignin, sugarcane bagasse, peanut shell, rice husk, egg cell etc.) are applied on various surfaces in order to develop fluorine free hydrophobic coatings with longer durability by lowering the surface energy and increasing the surface roughness. This review summarized recent developments in hydrophobic/superhydrophobic coating fabrication methods, properties and applications with the use of different bio-based materials and their combinations. In addition, basic mechanisms behind the coating fabrication process and their durability under different environmental conditions are also discussed. Moreover, prospects and limitations of bio-based coatings in practical applications have been highlighted.

Spatial and temporal variability of per- and polyfluoroalkyl substances (PFAS) in environmental media of a small pond: Toward an improved understanding of PFAS bioaccumulation in fish

Per- and polyfluoroalkyl substances (PFAS) are highly fluorinated compounds with many industrial applications, for instance as ingredients in fire-suppressing aqueous film-forming foams (AFFF). Several PFAS have been demonstrated to be persistent, bioaccumulative and toxic. This study better characterizes the bioaccumulation of PFAS in freshwater fish through a spatial and temporal analysis of surface water and sediment from a stormwater pond in a former Naval air station (NAS) with historic AFFF use. We sampled environmental media from four locations twice per week for five weeks and sampled fish at the end of the sampling effort. The primary PFAS identified in surface water, sediment, and biota were perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) followed by perfluorooctanoic acid (PFOA) in environmental media and perfluoroheptane sulfonate (PFHpS) in biota. We observed significant temporal variability in surface water concentrations at the pond headwaters following stochastic events such as heavy rainfall for many compounds, particularly PFHxS. Sediment concentrations varied most across sampling locations. In fish, liver tissue presented the highest concentrations for all compounds except PFHxS, which was highest in muscle tissue, suggesting the influence of fine-scale aqueous PFAS fluctuations on tissue distribution. Calculated log bioaccumulation factors (BAFs) ranged from 0.13 to 2.30 for perfluoroalkyl carboxylates (PFCA) and 0.29-4.05 for perfluoroalkane sulfonates (PFSA) and fluctuated greatly with aqueous concentrations. The variability of PFAS concentrations in environmental media necessitates more frequent sampling efforts in field-based studies to better characterize PFAS contamination in aquatic ecosystems as well as exercising caution when considering single time-point BAFs due to uncertainty of system dynamics.

Per/polyfluoroalkyl substances modulate plasmid transfer of antibiotic resistance genes: A balance between oxidative stress and energy support

Emerging contaminants can accelerate the transmission of antibiotic resistance genes (ARGs) from environmental bacteria to human pathogens via plasmid conjugation, posing a great challenge to the public health. Although the toxic effects of per/polyfluoroalkyl substances (PFAS) as persistent organic pollutants have been understood, it is still unclear whether and how PFAS modulate the transmission of ARGs. In this study, we for the first time reported that perfluorooctanoic acid (PFOA), perfluorododecanoic acid (PFDoA) and ammonium perfluoro (2-methyl-3-oxahexanoate) (GenX) at relatively low concentrations (0.01, 0.1 mg/L) promoted the conjugative transfer of plasmid RP4 within Escherichia coli, while the plasmid conjugation was inhibited by PFOA, PFDoA and GenX at relatively high concentrations (1, 10 mg/L). The non-unidirectional conjugation result was ascribed to the co-regulation of ROS overproduction, enhanced cell membrane permeability, shortage of energy support as well as l-arginine pool depletion. Taking the well-known PFOA as an example, it significantly enhanced the conjugation frequency by 1.4 and 3.4 times at relatively low concentrations (0.01, 0.1 mg/L), respectively. Exposure to PFOA resulted in enhanced cell membrane permeability and ROS overproduction in donor cells. At high concentrations of PFOA (1, 10 mg/L), although enhanced oxidative stress and cell membrane permeability still occurred, the ATP contents in E. coli decreased, which contributed to the inhibited conjugation. Transcriptome analysis further showed that the expression levels of genes related to arginine biosynthesis (argA, argC, argF, argG, argI) and transport (artJ, artM, artQ) pathways were significantly increased. Intracellular l-arginine concentration deficiency were observed at high concentrations of PFOA. With the supplementary exogenous arginine, it was demonstrated that arginine upregulated conjugation transfer- related genes (trfAp, trbBp) and restores the cell number of transconjugants in PFOA-treated group. Therefore, the inhibited conjugation at high concentrations PFOA were attributed to the shortage of ATP and the depletion of L-arginine pool. These findings provide important insights into the effect environmental concentrations of PFAS on the conjugative transfer of ARGs, and update the regulation mechanism of plasmid conjugation, which is critical for the management of antibiotic resistance in aquatic environments.

Impact of biological activated carbon filtration and backwashing on the behaviour of PFASs in drinking water treatment plants

PFASs are present in surface water, tap water and even commercial drinking water and pose a risk to human health. In this study, the treatment efficiency of 14 PFASs was studied in a large drinking water treatment plant (DWTP) using Taihu Lake as the source, and it was found that the ozone/biological activated carbon (O₃-BAC) process was the most effective process for the removal of PFASs in DWTPs. For the O₃-BAC process, there were differences in the removal of PFASs by BACs (1,4,7,13 years) of different ages. The sterilization experiments revealed that for GAC, its physical adsorption capacity reached saturation after one year, while for BAC with mature biofilms, biosorption was the main mechanism for the removal of PFASs. The abundance of Alphaproteobacteria and Gammaproteobacteria in biofilms was positively correlated with the age of the BAC. The microbial community with higher abundance is beneficial to the biodegradation of organic matter and thus provides more active sites for the adsorption of PFASs. PFASs can leak in the early stage of filtration after backwashing, so it is necessary to pay close attention to the influent and effluent concentrations of PFASs during biofilm maturation after backwashing.

Sources, occurrence and toxic effects of emerging per- and polyfluoroalkyl substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) cause potential threats to biota and are persistent and never-ending substances in the environment. Regulations and ban on legacy PFAS by various global organizations and national level regulatory agencies had shifted the fluorochemical production to emerging PFAS and fluorinated alternatives. Emerging PFAS are mobile and more persistent in aquatic systems, posing potential greater threats to human and environmental health. Emerging PFAS have been found in aquatic animals, rivers, food products, aqueous film-forming foams, sediments, and a variety of other ecological media. This review summarizes the physicochemical properties, sources, occurrence in biota and the environment, and toxicity of the emerging PFAS. Fluorinated and non-fluorinated alternatives for several industrial applications and consumer goods as the replacement of historical PFAS are also discussed in the review. Fluorochemical production plants and wastewater treatment plants are the main sources of emerging PFAS to various environmental matrices. Information and research are scarcely available on the sources, existence, transport, fate, and toxic effects of emerging PFAS to date.

Systematic review and meta-analysis of epidemiologic data on vaccine response in relation to exposure to five principal perfluoroalkyl substances

BACKGROUND

Epidemiologic studies of serum per- and polyfluoroalkyl substances (PFAS) and antibody response to vaccines have suggested an adverse association, but the consistency and magnitude of this association remain unclear.

OBJECTIVE

The goal of this systematic review was to determine the size of the association between a doubling in perfluoroalkyl substances (PFAS) serum concentration and difference in log_e antibody concentration following a vaccine, with a focus on five PFAS: perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA).

DATA SOURCE

We conducted online searches of PubMed and Web of Science through May 17, 2022 and identified 14 eligible reports published from 2012 to 2022.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

We included studies conducted in humans, including mother-child pairs, which examined serum PFAS concentration in relation to serum concentration of antibody to a specific antigen following a vaccine.

STUDY APPRAISAL AND SYNTHESIS METHODS

We used the risk of bias assessment for non-randomized studies of exposure and certainty assessment method proposed by Morgan et al. (2019). Using a multilevel meta-regression model, we quantitatively synthesized the data.

RESULTS

The 14 reports represented 13 unique groups of subjects; the frequency of studies of a given antibody was Tetanus (n = 7); followed by Diphtheria (6); Measles (4); Rubella (3); Haemophilus influenzae type b and Influenza A H1N1 (2 each); and Hepatitis A, Hepatitis B, Influenza A H2N3, Influenza B, and Mumps (1 each). There were approximately 4,830 unique participants included in the analyses across the 14 reports. The models of coefficients between antibody concentration and the five principal PFAS showed homogeneity of associations across antibody types for each principal PFAS. In the models with all antibodies treated as one type, evidence of effect modification by life stage was present for PFOA and PFOS, and for consistency, all associations were evaluated for all ages and for children. The summary associations (coefficients for difference in log_e[antibody concentration] per doubling of serum PFAS) with 95% confidence intervals that excluded zero ("statistical support"), and certainty of evidence ratings were as follows: for PFOA and all antibodies treated as one type in all ages, -0.06 (-0.10, -0.01; moderate) and in children, -0.10 (-0.16, -0.03; moderate); for Diphtheria in children, -0.12 (-0.23, -0.00; high); for Rubella in all ages, -0.09 (-0.17, -0.01; moderate), and for Tetanus in children, -0.12 (-0.24, -0.00; moderate). For PFOS the summary associations were, for all antibodies treated as one type in all ages, -0.06 (-0.11, -0.01; moderate) and in children, -0.10 (-0.18, -0.03; moderate); for Rubella in all ages, -0.09 (-0.15, -0.03; high) and in children, -0.12 (-0.20, -0.04; high). For PFHxS the summary associations were, for all antibodies treated as one type in all ages, -0.03 (-0.06, -0.00; moderate) and in children, -0.05 (-0.09, -0.00; low); and for Rubella in children, -0.07 (-0.11, -0.02; high). Summary associations for PFNA and PFDA did not have statistical support, but all PFAS studied tended to have an inverse association with antibody concentrations.

LIMITATIONS AND CONCLUSIONS

Epidemiologic data on immunosuppression and five principal PFAS suggest an association, with support across antibodies against multiple types of antigens. Data on Diphtheria, Rubella, and Tetanus were more supportive of an association than for other antibodies, and support was greater for associations with PFOA, PFOS, and PFHxS, than for PFNA or PFDA. The data on any specific antibody were scarce. Confounding factors that might account for the relation were not identified. Nearly all studies evaluated were judged to have a low or moderate risk of bias.

BDE-47 disturbs the immune response of lymphocytes to LPS by downregulating NF-κB pathway

The health risks associated with 2,2',4,4'-tetra-bromodiphenyl ether (BDE-47) have become an increasing concern due to its widespread presence in the environment and biological samples. To date, the potential toxicity of BDE-47 to immune system remains unclear. In this study, we aimed to study the immunotoxicity of BDE-47 using spleen-derived lymphocytes in vitro and BALB/c mice in vivo. In vitro results showed that lymphocytes exposed to 12.5-100 μM BDE-47 exhibited unchanged cell viability but decreased release of IL-6 and TNF-α when responding to lipopolysaccharide (LPS). The expression levels of p-p65, p-IκBα, TrkA and p-Akt involved in NF-κB pathway were obviously decreased, and NF-κB activator PMA could recover the BDE-47-induced inhibitory effect on IL-6 and TNF-α release by lymphocytes in response to LPS. In vivo data showed that BDE-47 orally administered to mice (1 mg/kg, 10 mg/kg, 100 mg/kg per day, 30 days) did not significantly affect body weight, organ index and histomorphology of spleen. However, ELISA assay showed that serum IL-6 and TNF-α levels from BDE-47-treated mice after intraperitoneal injection of LPS were significantly reduced, and high-throughput mouse cytokines screening found 13 more cytokines down-regulated in the serum. Transcriptomic sequencing of spleens identified 488 differential expressed genes (DEGs). GO enrichment analysis of these DEGs suggested that the GO term of response to LPS (GO: 0032,496) was significantly involved. KEGG enrichment analysis showed that the down-regulated DEGs significantly enriched in multiple immune-related signaling pathways including the NF-κB signaling pathway (mmu04064). Overall, these data suggested that BDE-47 could negatively regulate NF-κB signaling pathways to inhibit the immune response of lymphocytes to LPS, suggesting that exposures to BDE-47 may disturb the immune balance and increase the body's susceptibility to infectious diseases.

Thermoresponsive Cationic Polymers: PFAS Binding Performance under Variable pH, Temperature and Comonomer Composition

The versatility and unique qualities of thermoresponsive polymeric systems have led to the application of these materials in a multitude of fields. One such field that can significantly benefit from the use of innovative, smart materials is environmental remediation. Of particular significance, multifunctional poly(N-isopropylacrylamide) (PNIPAAm) systems based on PNIPAAm copolymerized with various cationic comonomers have the opportunity to target and attract negatively charged pollutants such as perfluorooctanoic acid (PFOA). The thermoresponsive cationic PNIPAAm systems developed in this work were functionalized with cationic monomers N-[3-(dimethylamino)propyl]acrylamide (DMAPA) and (3-acrylamidopropyl)trimethylammonium chloride (DMAPAQ). The polymers were examined for swelling capacity behavior and PFOA binding potential when exposed to aqueous environments with varying pH and temperature. Comonomer loading percentages had the most significant effect on polymer swelling behavior and temperature responsiveness as compared to aqueous pH. PFOA removal efficiency was greatly improved with the addition of DMAPA and DMAPAQ monomers. Aqueous pH and buffer selection were important factors when examining binding potential of the polymers, as buffered aqueous environments altered polymer PFOA removal quite drastically. The role of temperature on binding potential was not as expected and had no discernible effect on the ability of DMAPAQ polymers to remove PFOA. Overall, the cationic systems show interesting swelling behavior and significant PFOA removal results that can be explored further for potential environmental remediation applications.

Evaluation of 147 perfluoroalkyl substances for immunotoxic and other (patho)physiological activities through phenotypic screening of human primary cells

A structurally diverse set of 147 per- and polyfluoroalkyl substances (PFAS) was screened in a panel of 12 human primary cell systems by measuring 148 biomarkers relevant to (patho)physiological pathways to inform hypotheses about potential mechanistic effects of data-poor PFAS in human model systems. This analysis focused on immunosuppressive activity, which was previously reported as an in vivo effect of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), by comparing PFAS responses to four pharmacological immunosuppressants. The PFOS response profile had little correlation with reference immunosuppressants, suggesting in vivo activity does not occur by similar mechanisms. The PFOA response profile did share features with the profile of dexamethasone, although some distinct features were lacking. Other PFAS, including 2,2,3,3-tetrafluoropropyl acrylate, demonstrated more similarity to the reference immunosuppressants but with additional activities not found in the reference immunosuppressive drugs. Correlation of PFAS profiles with a database of environmental chemical responses and pharmacological probes identified potential mechanisms of bioactivity for some PFAS, including responses similar to ubiquitin ligase inhibitors, deubiquitylating enzyme (DUB) inhibitors, and thioredoxin reductase inhibitors. Approximately 21% of the 147 PFAS with confirmed sample quality were bioactive at nominal testing concentrations in the 1-60 micromolar range in these human primary cell systems. These data provide new hypotheses for mechanisms of action for a subset of PFAS and may further aid in development of a PFAS categorization strategy useful in safety assessment.

Effects of endocrine disrupting chemicals on the expression of RACK1 and LPS-induced THP-1 cell activation

The existence of a complex hormonal balance among glucocorticoids, androgens and estrogens involved in the regulation of Receptor for Activated C Kinase 1 (RACK1) expression and its related immune cells activation, highlights the possibility to employ this protein as screening tool for the evaluation of the immunotoxic profile of endocrine disrupting chemicals (EDCs), hormone-active substances capable of interfering with the physiologic hormonal signaling. Hence, the aim of this work was to investigate the effect of the exposure of EDCS 17α-ethynylestradiol (EE), diethyl phthalate (DEP) and perfluorooctanesulfonic acid (PFOS) on RACK1 expression and on lipopolysaccharide (LPS)-induced activation of the human monocytic cell line THP-1, a validated model for this investigation. In line with our previous results with estrogen-active compounds, EE treatment significantly induced RACK1 promoter transcriptional activity, mRNA expression, and protein levels, which paralleled an increase in LPS-induced IL-8, TNF-α production and CD86 expression, previously demonstrated to be dependent on RACK1/PKCβ activation. EE mediates its effect on RACK1 expression through G-protein-coupled estrogen receptor (GPER) and androgen receptor (AR) ligand-independent cascade, as also suggested by in silico molecular docking simulation. Conversely, DEP and PFOS induced a dose-dependent downregulation of RACK1 promoter transcriptional activity, mRNA expression, and protein levels, which was mirrored by a reduction of IL-8, TNF-α production and CD86 expression. Mifepristone pre-treatments abolish DEP and PFOS effects, confirming their GR agonist profile, also corroborated by molecular docking. Altogether, our data confirm that RACK1 represents an interesting target of steroid active compounds, which expression offers the opportunity to screen the immunotoxic potential of different hormone-active substances of concerns due to their human exposure and environmental persistence.

Occurrence of Perfluoroalkyl and Polyfluoroalkyl Substances in Ice Cream, Instant Noodles, and Bubble Tea

Food consumption is a significant exposure route to perfluoroalkyl and polyfluoroalkyl substances (PFAS). The concentrations of 27 PFAS in fast food were determined by ultrahigh-performance liquid chromatography-high resolution mass spectrometry. In ice cream, instant noodles, and bubble tea, some PFAS were detected, among which perfluorooctanoic acid, perfluoro-n-butanoic acid, and 6:2 polyfluoroalkyl phosphate monoester showed relatively high concentrations. PFAS migrating from bubble tea cups to the food simulant of 50% ethanol aqueous solution showed a difference compared with those migrating into bubble tea matrices. The migration of 27 PFAS to bubble tea samples indicated that long storage time increased PFAS levels (up to 4.8 times) and so did high storage temperature (up to 7.3 times). The hazard ratio, defined as the ratio of the estimated daily intake and the reference dose, was calculated, and it suggests that the total PFAS exposure risk due to consumption of bubble tea should be of concern.

Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) modify in vitro mitogen- and antigen-induced human peripheral blood mononuclear cell (PBMC) responses

Environmental contaminants perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are present in human serum at the highest concentration among all per- and polyfluoroalkyl substances (PFAS). Serum concentrations as high as 500 ng and 3000 ng PFOA/ml have been detected in individuals living near contamination sites and those occupationally exposed, respectively. Animal and human studies indicated that PFOA and PFOS at these serum concentrations perturb the immune system. The aim of this study was to examine the effects of in vitro exposure of human peripheral blood mononuclear cells (PBMC) to 1, 10, or 100 µM PFOA or PFOS in a medium with serum (RPMI-1640 + 5% human AB serum) on the measurement of proliferation, T cell activation, generation of memory T cells, and cytokine production/secretion. In addition, these immune system parameters were assessed for PBMC in a serum-free medium (OpSFM), which was stimulated with phytohemagglutinin (PHA) (2.5 µg/ml) or influenza vaccine antigen (0.625 µg/ml Flu Ag). PFOS decreased proliferation stimulated by PHA or Flu Ag. With Flu Ag stimulation, PFOA and PFOS inhibited the generation of memory T cells in a concentration-dependent manner. In OpSFM, PFOA and PFOS produced no marked change in proliferation and no inhibition of T cell activation. Cytokines measured in the media with Luminex methodology indicated decreased PBMC secretion of IFN-γ by PFOA and PFOS in medium with serum, but no alteration in OpSFM. The results indicated that changes in immune parameters due to PFOA or PFOS following Flu Ag stimulation are medium (±serum) dependent.

Association between serum per- and polyfluoroalkyl substances concentrations and common cold among children and adolescents in the United States

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exert immunosuppressive effects in experimental animals. Few epidemiologic studies investigated PFAS exposure and immune-related clinical outcomes such as common cold, especially during childhood when the immune system is developing.

METHODS

This study used data from the National Health and Nutrition Examination Survey and included 517 children 3-11 years (2013-2014 cycle) and 2732 adolescents 12-19 years (2003-2016 cycles). Serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) were quantified. Common cold was self-reported by the participant or parent as having a head cold or chest cold in the last month. Multivariable logistic regression models were applied to examine the covariate-adjusted odds ratios (ORs) between individual PFAS concentrations and common cold incidence in the past month. The joint effect of PFAS mixtures was evaluated using Probit Bayesian Kernel Machine Regression (BKMR).

RESULTS

A doubling of serum PFHxS concentration was associated with a 31% higher odds (OR = 1.31, 95% CI: 1.06, 1.62) of common cold among children. Serum PFNA (OR = 1.36, 95% CI: 0.93, 1.98) and PFOA (OR = 1.32, 95% CI: 0.67, 2.62) concentrations were also related to common cold among children, as were serum PFOS concentrations among adolescents (OR = 1.13, 95% CI: 0.96, 1.32). ORs were higher in male than female children and adolescents. BKMR showed a clear increasing trend of common cold estimates across quantiles of the total PFAS mixture concentration among children, while no obvious pattern emerged in adolescents.

DISCUSSION

Among children in the United States, serum concentrations of PFAS mixtures, especially PFHxS and PFNA, were associated with higher odds of common cold. Among adolescents, PFOS was associated with increased common cold in the last month. This study contributes to the existing evidence supporting the immunotoxicity of PFAS in childhood and adolescence.

Emerging contaminants of high concern for the environment: Current trends and future research

Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants.

The immune modulatory role of marjoram extract on imidacloprid induced toxic effects in thymus and spleen of adult rats

Imidacloprid (IMID), one of environmental persistent neonicotinoid insecticides, has been used a long time ago and categorized from insecticide induced moderate toxicity by World Health Organization (WHO). Marjoram, is one of the most worldwide used herbs in Egypt due to its antioxidant, anti-inflammatory, anti-genotoxic, anti-mutagenic, anticoagulant, and beneficial effects. This study aimed to evaluate the protective role of marjoram extract on the immunotoxic response and oxidative stress induced by IMID in the immune lymphoid organs (thymus and spleen) of rats. Fifty adult male albino rats were divided randomly into five groups; negative and positive (distilled water) control, marjoram extract (200 mg/kg/day), IMID (22.5 mg/kg/day), marjoram extract + IMID (200 mg/kg +22.5 mg/kg) orally for 8 weeks. Marjoram pretreatment reversed reduced animals body, thymus and spleen weights attributed to IMID. It amended the significantly elevated total leukocytes, neutrophils percentage, increased immunoglobulin G and the significantly reduction of lymphocytes percentage, phagocytic activity, phagocytic index and lysozyme activity induced by IMID. Moreover, marjoram administration significantly reduced thymic and splenic gene expression of interleukin-1β, interleukin-6, tumor necrosis factor-α and increased interleukin-10, in addition, it decreased thymic and splenic contents of malondialdehyde and restored the reduced antioxidant enzymes' activities following IMID exposure. Marjoram ameliorated IMID induced histopathological alterations in thymus and spleen and adjusted IMID immunomodulatory effects by increased the downregulation of CD4 and CD8 immune reactive cell expression. Conclusion, Marjoram has a protective role to reverse IMID immune toxic effects in thymus and spleen tissues of rats by its antioxidant, anti-inflammatory and immunomodulatory defense mechanisms.

Translatability and transferability of in silico models: context of use switching to predict the effects of environmental chemicals on the immune system

Immunotoxicity hazard identification of chemicals aims to evaluate the potential for unintended effects of chemical exposure on the immune system. Perfluorinated alkylate substances (PFAS), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are persistent, globally disseminated environmental contaminants known to be immunotoxic. Elevated PFAS exposure is associated with lower antibody responses to vaccinations in children and in adults. In addition, some studies have reported a correlation between PFAS levels in the body and lower resistance to disease, in other words an increased risk of infections or cancers.

In this context, modelling and simulation platforms could be used to simulate the human immune system with the aim to evaluate the adverse effects that immunotoxicants may have.

Here, we show the conditions under which a mathematical model developed for one purpose and application (e.g., in the pharmaceutical domain) can be successfully translated and transferred to another (e.g., in the chemicals domain) without undergoing significant adaptation. In particular, we demonstrate that the Universal Immune System Simulator was able to simulate the effects of PFAS on the immune system, introducing entities and new interactions that are biologically involved in the phenomenon. This also revealed a potentially exploitable pathway for assessing immunotoxicity through a computational model.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

Evaluation of single and joint toxicity of perfluorooctanoic acid and arsenite to earthworm (Eisenia fetida): A multi-biomarker approach

Perfluorooctanoic acid (PFOA) and arsenic are ubiquitous environmental contaminants and could co-exist in soil. However, data on their possible combined toxic effects on terrestrial organisms are still lacking. In this study, we exposed earthworm Eisenia fetida to artificial soil spiked with different sub-lethal levels of PFOA, arsenite (As(III)) or their mixture for 28 days. The bioaccumulation and multi-biomarker responses in the earthworms were measured. Results showed that the co-existence of PFOA and As(III) in soil enhanced the bioaccumulation of arsenic while reduced the bioaccumulation of PFOA. Most selected biomarkers exhibited significant responses at higher exposure levels and indicated oxidative damages. Biomarker Response Index (BRI) was used to integrate the multi-biomarker responses and the results showed significant dose-effect relationships between biological health status and exposure levels. Moreover, variation analysis of multi-biomarkers and BRI proved that As(III) exhibited more toxicity than PFOA to the earthworms. Based on BRI results, Effect Addition Index (EAI) was calculated to evaluate the joint effects of the two toxicants. According to EAI, the joint toxicity of PFOA and As(III) was related to exposure concentration, changing from synergism to slight antagonism with the increase of exposure level. These results provide valuable toxicological information for the risk assessment of co-exposure to PFOA and arsenic in the soil environment. Moreover, this study proved that BRI is an effective tool to integrate multi-biomarker responses, and its combination with EAI provides a useful combined approach to evaluate the joint effects of mixed contamination systems.

Per- and polyfluoroalkyl substances in water and wastewater: A critical review of their global occurrence and distribution

Per- and polyfluoroalkyl substances (PFAS) are a family of fluorinated organic compounds of anthropogenic origin. Due to their unique chemical properties, widespread production, environmental distribution, long-term persistence, bioaccumulative potential, and associated risks for human health, PFAS have been classified as persistent organic pollutants of significant concern. Scientific evidence from the last several decades suggests that their widespread occurrence in the environment correlates with adverse effects on human health and ecology. The presence of PFAS in the aquatic environment demonstrates a close link between the anthroposphere and the hydrological cycle, and concentrations of PFAS in surface and groundwater range in value along the ng L^-1-μg L^-1 scale. Here, we critically reviewed the research published in the last decade on the global occurrence and distribution of PFAS in the aquatic environment. Ours is the first paper to critically evaluate the occurrence of PFAS at the continental scale and the evolving global regulatory responses to manage and mitigate the adverse human health risks posed by PFAS. The review reports that PFAS are widespread despite being phased out-they have been detected in different continents irrespective of the level of industrial development. Their occurrence far from the potential sources suggests that long-range atmospheric transport is an important pathway of PFAS distribution. Recently, several studies have investigated the health impacts of PFAS exposure-they have been detected in biota, drinking water, food, air, and human serum. In response to the emerging information about PFAS toxicity, several countries have provided administrative guidelines for PFAS in water, including Canada, the United Kingdom, Sweden, Norway, Germany, and Australia. In the US, additional regulatory measures are under consideration. Further, many PFAS have now been listed as persistent organic pollutants. This comprehensive review provides crucial baseline information on the global occurrence, distribution, and regulatory framework of PFAS.

Uncovering Evidence: Associations between Environmental Contaminants and Disparities in Women's Health

Over the years, industrial accidents and military actions have led to unintentional, large-scale, high-dose human exposure to environmental contaminants with endocrine-disrupting action. These historical events, in addition to laboratory studies, suggest that exposure to toxicants such as dioxins and polychlorinated biphenyls negatively impact the reproductive system and likely influence the development of gynecologic diseases. Although high-level exposure to a single toxicant is rare, humans living in industrialized countries are continuously exposed to a complex mixture of manmade and naturally produced endocrine disruptors, including persistent organic pollutants and heavy metals. Since minorities are more likely to live in areas with known environmental contamination; herein, we conducted a literature review to identify potential associations between toxicant exposure and racial disparities in women's health. Evidence within the literature suggests that the body burden of environmental contaminants, especially in combination with inherent genetic variations, likely contributes to previously observed racial disparities in women's health conditions such as breast cancer, endometriosis, polycystic ovarian syndrome, uterine fibroids, and premature birth.

Serum vaccine antibody concentrations in adults exposed to per- and polyfluoroalkyl substances: A birth cohort in the Faroe Islands

Per- and polyfluoroalkyl substances (PFASs) are highly persistent in the environment and may cause depressed immune function. Previous studies have linked PFAS exposure to lower vaccine responses in children, but research in adults is limited. Therefore, the present study evaluated the associations between exposure to PFASs and serum antibody concentrations in adults vaccinated at age 28 years in the Faroe Islands. PFAS concentrations were determined from cord-blood collected at birth and serum samples collected at ages 7, 14, 22, and 28 years. Serum antibody concentrations against hepatitis type A and B, diphtheria, and tetanus were analyzed from blood samples collected about 6 mo after the first vaccine inoculation at age 28 years. Linear regression models were used to estimate changes in antibody concentration for each doubling of PFAS concentration. Potential effect modification by sex was assessed by including an interaction term between PFAS and sex. Although the 95% confidence intervals contain the null value, inverse trends were observed between serum perfluorooctanoate (PFOA) at ages 14 and 28 years and hepatitis type A antibody (anti-HAV) concentrations, as revealed by an estimated decrease of 0.71 (95% CI: -1.52, 0.09) and 0.24 (95% CI: -0.59, 0.10) signal-to-cutoff ratio for each doubling of exposure, respectively. Inverse trends were also observed between serum PFOA at ages 22 and 28 years and hepatitis type B antibody (anti-HBs) concentration, with an estimated decrease of 21% (95% CI: -42.20%, 7.34%) and of 17% (95% CI: -35.47%, 7.35%) in anti-HBs for each doubling of exposure, respectively. Sex-specific associations with anti-HAV were observed for cord-blood PFASs and serum PFAS concentrations at ages 7 and 14 years. No inverse associations of PFAS exposure were found with diphtheria and tetanus antibody concentrations. Future studies are needed to confirm these findings and further investigate the effects of PFASs on adult immune function.

Hexafluoropropylene oxide dimer acid (GenX) exposure induces apoptosis in HepG2 cells

Hexafluoropropylene oxide dimer acid, also known as GenX, is a poly- and perfluoroalkyl substance (PFAS). PFASs are nonvolatile synthetic substances that can be readily disseminated into the environment during processing and use, making them easy to implement in the soil, drinking water, and air. Compared to other PFASs, GenX has a comparatively short carbon chain length and is expected to have a lower tendency to accumulate in humans; therefore, GenX has recently been used as a substitute to other PFASs. However, the mechanisms underlying GenX action and intoxication in humans remains unclear. In this study, the apoptotic capacity of GenX in human liver cells was investigated. When representative human-derived liver cells (HepG2 cells) were treated with GenX for 12 h, cell viability was reduced, and apoptosis was greatly increased. In addition, GenX increased the generation of intracellular reactive oxygen species (ROS), indicating the induction of oxidative stress in a dose-dependent manner. GenX treatment increased the expression of major apoptosis-related genes relative to the untreated control group. This research indicates that GenX causes apoptosis through ROS mediation in HepG2 cells, which may expand our knowledge of the molecular and toxicological mechanisms of GenX.

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Hexafluoropropylene oxide dimer acid (GenX) can be harmful to the liver.

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Through the mediation of ROS, GenX causes apoptosis in HepG2 cells.

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GenX activates Bax, caspase 3/9, CHOP, and p53 via the apoptosis.

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The intrinsic pathway links GenX mode of action to apoptosis-related stimuli.

Mitochondria damage in ambient particulate matter induced cardiotoxicity: Roles of PPAR alpha/PGC-1 alpha signaling

Particulate matter (PM) had been associated with cardiotoxicity, while the mechanism of toxicity has yet to be elucidated, with mitochondria dysfunction as a potential candidate. To investigate the potential cardiotoxic effects of ambient PM exposure and assess the damage to cardiac mitochondria, C57/B6 mice were exposed to filtered air or real ambient PM for three or six weeks. Furthermore, to reveal the role of peroxisome proliferators-activated receptor alpha (PPAR alpha) in PM exposure induced cardiotoxicity/mitochondria damage, animals were also co-treated with PPAR alpha agonist WY 14,643 or PPAR alpha antagonist GW 6471. Cardiotoxicity was assessed with echocardiography and histopathology, while mitochondria damage was evaluated with mitochondria membrane potential measurement and transmission electron microscopy. Potential impacts of PM exposure to PPAR alpha signaling were detected with co-immunoprecipitation and western blotting. The results indicated that exposure to ambient PM exposure induced cardiotoxicity in C57/B6 mice, including altered cardiac functional parameters and morphology. Cardiac mitochondria damage is detected, in the form of compromised mitochondria membrane potential and morphology. Molecular investigations revealed disruption of PPAR alpha interaction with peroxisome proliferator-activated receptor gamma coactivator-1A (PGC-1a) as well as altered expression levels of PPAR alpha downstream genes. Co-treatment with WY 14,643 alleviated the observed toxicities, while co-treatment with GW 6471 had mixed results, exaggerating most cardiotoxicity and mitochondrial damage endpoints but alleviating some cardiac functional parameters. Interestingly, WY 14,643 and GW 6471 co-treatment seemed to exhibit similar regulative effects towards PPAR alpha signaling in animals exposed to PM. In conclusion, ambient PM exposure indeed induced cardiotoxicity in C57/B6 mice, in which cardiac mitochondria damage and disrupted PPAR alpha signaling are contributors.

Lipidomic Analyses Reveal Modulation of Lipid Metabolism by the PFAS Perfluoroundecanoic Acid (PFUnDA) in Non-Obese Diabetic Mice

Exposure to Per- and polyfluoroalkyl substances (PFAS) has been linked to multiple undesirable health outcomes across a full lifespan, both in animal models as well as in human epidemiological studies. Immunosuppressive effects of PFAS have been reported, including increased risk of infections and suppressed vaccination responses in early childhood, as well as association with immunotoxicity and diabetes. On a mechanistic level, PFAS exposure has been linked with metabolic disturbances, particularly in lipid metabolism, but the underlying mechanisms are poorly characterized. Herein we explore lipidomic signatures of prenatal and early-life exposure to perfluoroundecanoic acid (PFUnDA) in non-obese diabetic (NOD) mice; an experimental model of autoimmune diabetes. Female NOD mice were exposed to four levels of PFUnDA in drinking water at mating, during gestation and lactation, and during the first weeks of life of female offspring. At offspring age of 11–12 weeks, insulitis and immunological endpoints were assessed, and serum samples were collected for comprehensive lipidomic analyses. We investigated the associations between exposure, lipidomic profile, insulitis grade, number of macrophages and apoptotic, active-caspase-3-positive cells in pancreatic islets. Dose-dependent changes in lipidomic profiles in mice exposed to PFUnDA were observed, with most profound changes seen at the highest exposure levels. Overall, PFUnDA exposure caused downregulation of phospholipids and triacylglycerols containing polyunsaturated fatty acids. Our results show that PFUnDA exposure in NOD mice alters lipid metabolism and is associated with pancreatic insulitis grade. Moreover, the results are in line with those reported in human studies, thus suggesting NOD mice as a suitable model to study the impacts of environmental chemicals on T1D.

Perfluorinated compounds disrupted osmoregulation in Oryzias melastigma during acclimation to hypoosmotic environment

Perfluorinated compounds (PFCs) are a type of ubiquitous contaminants spreading in the estuarine and coastal areas. Anadromous fish should deal with hypoosmotic challenge with PFCs stress during their migration from seawater to estuaries. However, few studies have been carried out to investigate the adverse impact of PFCs on fish osmoregulation and the underlying mechanism. In this study, Oryzias melastigma, an euryhaline fish model, were exposed to four representative PFC congeners including perfluorobutane sulfonate (PFBS), perfluorooctane sulfonates (PFOS), perfluorooctanoic acid (PFOA), and perfluorododecanoic acid (PFDoA) separately under both seawater and freshwater conditions. Histopathological changes in gills, ion homeostasis, Na⁺/K⁺-ATPase (NKA) activity, as well as the expression of related genes was detected upon exposure. Results showed that PFCs induced morphological changes in gills, disturbed the levels of major ions (Na⁺, Ca²⁺, Mg²⁺), and inhibited the NKA activity. Transcriptome analysis in fish gills during the acclimation to freshwater revealed that PFCs influenced the osmoregulation mainly by interfering with the endocrine system, signal transduction, as well as cellular community and motility. Validation with qRT-PCR confirmed that the mRNA expressions of osmoregulatory genes encoding hormones and receptors, as well as ion transmembrane transporters were disturbed by PFCs. Longer chain homolog (PFOS) showed a greater impact on osmoregulation than the shorter chain homolog (PFBS). Within the same carbon chain, sulfonic congener (PFOS) induced more serious injury to gills than carboxylic congener (PFOA). The interaction between PFCs and salinity varied in different adverse outcome. These results help to further understand the mechanism of how PFCs influence osmoregulation and elicit the need to assess the ecological risk of PFCs and other pollutants on anadromous migration.

Suppression of Th2 cytokines as a potential mechanism for reduced antibody response following PFOA exposure in female B6C3F1 mice

Perfluorooctanoic acid (PFOA), a member of the Per- and polyfluoroalkyl substances, is a highly persistent "forever" chemicals with increasing concern for its potential health effects. However, the mechanisms of PFOA immunotoxic effects are poorly understood. We assessed the antibody response to a physiological antigen stimulation and associated cytokine response upon PFOA exposure. The significant decrease in the IgM antibody response to the T cell dependent antigen keyhole limpet hemocyanin (KLH) at a dose lower than the previously documented LOAEL was accompanied by a significant reduction of the Th2 serum cytokines IL-5 and IL-13, a non-significant dose-response reduction of IL-4, a significant reduction of the Th1 cytokine IL-12, and a non-significant dose-response increase in IL-2 and IFNγ. PFOA significantly decreased the pro-inflammatory cytokines IL-17α and IL-1α, decreased (non-significantly but dose-response) IL-6, and a significantly increased TNFα. Overall, the modulation of serum Th1/Th2 cytokines could explain the reduction in antibody response, pointing to a potential role for T helper cells in the immunotoxicity of PFOA. Further, the higher than anticipated weight loss and increased liver weight, compared to previous studies using similar doses, highlight the potential importance of the route and duration of exposure, contributing to the total accumulated dose, in assessing the toxicity of PFOA.

A graphene-based hydrogel monolith with tailored surface chemistry for PFAS passive sampling

Aquatic contamination by per- and polyfluorinated alkyl substances (PFAS) has attracted global attention due to their environmental and health concerns. Current health advisories and surface water regulatory limits require PFAS detection in the parts per trillion (ppt) range. One way to achieve those low detection limits is to use a reliable passive sampling-based monitoring tool for PFAS, as exists for numerous nonpolar persistent organic pollutants. Here we introduce a new graphene-based hydrogel monolith and describe its synthesis, chemical functionalization, property characterization, and testing as a PFAS equilibrium passive sampler. The graphene monoliths were self-assembled by hydrothermal treatment from graphene oxide (GO) aqueous dispersions to produce free standing cylinders of ~563 mm³ volume consisting of ~4 wt-% thin-walled porous graphene and ~96 wt-% water. The uptake of 23 PFAS was measured on the as-produced monoliths, and equilibrium partition coefficients (K_SW), were derived for longer chain (C≥8) perfluoroalkyl acids (PFAA) and neutral precursors such as sulfonamides (log K_SW range 1.9 - 3.6). To increase the K_SW for shorter chain PFAA, the monoliths were chemically modified by a new diazonium-based grafting reaction that introduces positive surface charge without damage to the graphenic backbone. Introduction of benzylamine moieties through the diazonium intermediate switches zeta potential at pH 7 from -45mV (as-produced graphene) to + 5mV. This modification increased the sorption of short and middle chain PFAA by ten-fold (e.g. log K_SW for PFBA increased from 1.3 to 2.2), thereby improving the functionality of the passive sampler device for a wider range of PFAS. Field deployments demonstrated that the graphene monoliths were capable of detecting key PFAS in the Delaware River.

Photooxidative decomposition and defluorination of perfluorooctanoic acid (PFOA) using an innovative technology of UV-vis/ZnxCu1-xFe2O4/oxalic acid

Per- and polyfluoroalkyl substances (PFAS) are a large group of perfluorinated organic molecules that have been in use since the 1940s for industrial, commercial, and consumer applications. PFAS are a growing concern because some of them have shown persistent, bioaccumulative and toxic effects. Herein, we demonstrate an innovative technology of UV-vis/Zn_xCu_1-xFe₂O₄/oxalic acid for the degradation of perfluorooctanoic acid (PFOA) in water. The magnetically retrievable nanocrystalline heterogeneous ferrite catalysts, Zn_xCu_1-xFe₂O₄ were synthesized using a sol-gel auto-combustion process followed by calcination at 400 °C. The combination of Zn_xCu_1-xFe₂O₄ and oxalic acid generate reactive species under UV light irradiation. These reactive species are then shown to be capable of the photodegradation of PFOA. The degree of degradation is tracked by identifying transformation products using liquid chromatography coupled with quadrupole time-of-flight mass spectroscopy (LC-QTOF-MS).

Simultaneous determination of 9 environmental pollutants including bisphenol A in vegetable oil by solid phase extraction-liquid chromatography-tandem mass spectrometry

In this study, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with solid phase extraction was established for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil. The sample was extracted with ammonia acetonitrile solution (1 : 9, V/V) by ultrasonication. And the obtained extract was purified by using a PRIME HLB solid phase extraction column. The identification and quantification of the compounds was performed by liquid chromatography-tandem mass spectrometry in multiple reaction monitoring (MRM) mode. The internal standard method was used for quantitative analysis. Under optimal experimental conditions, the limits of quantitation of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol and n-octylphenol in vegetable oil were 1.0 μg kg-1. The limits of quantitation of perfluorooctane sulfonic acid and perfluorooctanoic acid in vegetable oil were 0.1 μg kg-1. The average spiked recoveries of the method were in the range of 89.2-117.1% with the relative standard deviations (RSD) of 2.9-9.8% (n = 6). This method is sensitive, versatile and reproducible, and is suitable for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil.

Understanding the Impact of Perfluorinated Compounds on Cardiovascular Diseases and Their Risk Factors: A Meta-Analysis Study

Perfluorinated compounds (PFCs) are non-biodegradable synthetic chemical compounds that are widely used in manufacturing many household products. Many studies have reported the association between PFCs exposure with the risk of developing cardiovascular diseases (CVDs). However, those reports are still debatable, due to their findings. Thus, this review paper aimed to analyse the association of PFCs compound with CVDs and their risk factors in humans by systematic review and meta-analysis. Google Scholar, PubMed and ScienceDirect were searched for PFCs studies on CVDs and their risk from 2009 until present. The association of PFCs exposure with the prevalence of CVDs and their risk factors were assessed by calculating the quality criteria, odds ratios (ORs), and 95% confidence intervals (CIs). CVDs risk factors were divided into serum lipid profile (main risk factor) and other known risk factors. The meta-analysis was then used to derive a combined OR test for heterogeneity in findings between studies. Twenty-nine articles were included. Our meta-analysis indicated that PFCs exposure could be associated with CVDs (Test for overall effect: z = 2.2, p = 0.02; Test for heterogeneity: I² = 91.6%, CI = 0.92–1.58, p < 0.0001) and their risk factors (Test for overall effect: z = 4.03, p < 0.0001; Test for heterogeneity: I² = 85.8%, CI = 1.00–1.14, p < 0.0001). In serum lipids, total cholesterol levels are frequently reported associated with the exposure of PFCs. Among PFCs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) exposure increased the risk of CVDs than other types of PFCs. Although the risk of PFOA and PFOS were positively associated with CVDs and their risk factors, more observational studies shall be carried out to identify the long-term effects of these contaminants in premature CVDs development in patients.

Exposure, health effects, sensing, and remediation of the emerging PFAS contaminants - Scientific challenges and potential research directions

Per- and polyfluoroalkyl substances (PFAS) make up a large group of persistent anthropogenic chemicals which are difficult to degrade and/or destroy. PFAS are an emerging class of contaminants, but little is known about the long-term health effects related to exposure. In addition, technologies to identify levels of contamination in the environment and to remediate contaminated sites are currently inadequate. In this opinion-type discussion paper, a team of researchers from the University of Connecticut and the University at Albany discuss the scientific challenges in their specific but intertwined PFAS research areas, including rapid and low-cost detection, energy-saving remediation, the role of T helper cells in immunotoxicity, and the biochemical and molecular effects of PFAS among community residents with measurable PFAS concentrations. Potential research directions that may be employed to address those challenges and improve the understanding of sensing, remediation, exposure to, and health effects of PFAS are then presented. We hope our account of emerging problems related to PFAS contamination will encourage a broad range of scientific experts to bring these research initiatives addressing PFAS into play on a national scale.

Effect of resveratrol on the inflammatory status and oxidative stress in thymus gland and spleen of sulfoxaflor-treated rats

Resveratrol (Res), a polyphenolic compound that exerts mitigating consequences against various insults due to its antioxidant, anti-inflammatory, and immunomodulatory properties. Sulfoxaflor (SFX), a neonicotinoid insecticide, has been used worldwide and leading to deleterious effects on the environment and public health. The current study aimed to investigate the protective effect of Res on the inflammatory response and oxidative stress induced by SFX in the thymus and spleen of rats. Thirty-six Sprague Dawley rats were divided randomly into six groups; control group, SFX treated groups (24.8 mg/kg or 79.4 mg/kg/day), Res (alone) treated group (20 mg/kg/day), Res + SFX treated groups (20 mg /kg Res + 24.8 mg/kg SFX or 20 mg/kg Res + 79.4 mg/kg SFX) orally for 28 days. Res treatment reversed the significantly elevated white blood cells' count and the reduced count of red blood corpuscles, platelets as well as hemoglobin content of SFX treated rats. Biochemically, Res administration inhibited the remarkably increased serum levels of the inflammatory cytokines as well as thymic and splenic levels of malondialdehyde following SFX treatment. Res treatment ameliorated the conspicuously reduced antioxidant enzymes' activities due to SFX supplementation. The immunomodulatory effect of Res treatment was detected by suppressing the upregulation of the cluster of differentiation (CD)11b and CD3 gene expressions. Histopathological alterations attributed to SFX administration were ameliorated by Res treatment. In conclusion, Res can be used as a protective agent to counteract SFX toxic effects on lymphatic organs through alleviation of the antioxidant defense mechanism and modulation of the inflammatory response.

An In Silico and In Vitro study for Investigating Estrogenic Endocrine Effects of Emerging Persistent Pollutants using Primary Hepatocytes from Grey Mullet (Mugil Cephalus)

There is growing concern about the environmentally relevant concentrations of new emerging persistent organic pollutants, such as perfluorinated compounds and pharmaceuticals, which are found to bioaccumulate in aquatic organisms at concentrations suspected to cause reproductive toxicity due to the activation of estrogen receptor (ER) α and β subtypes. Here, we use a combined in silico and in vitro approach to evaluate the impact of perfluorononanoic acid (PFNA) and Enalapril (ENA) on grey mullet (Mugil cephalus) hepatic estrogen signaling pathway. ENA had weak agonist activity on ERα while PFNA showed moderate to high agonist binding to both ERs. According to these effects, hepatocytes incubation for 48 h to PFNA resulted in a concentration-dependent upregulation of ER and vitellogenin gene expression profiles, whereas only a small increase was observed in ERα mRNA levels for the highest ENA concentration. These data suggest a structure–activity relationship between hepatic ERs and these emerging pollutants.

Inactivation of common airborne antigens by perfluoroalkyl chemicals modulates early life allergic asthma

Allergic asthma, driven by T helper 2 cell-mediated immune responses to common environmental antigens, remains the most common respiratory disease in children. Perfluorinated chemicals (PFCs) are environmental contaminants of great concern, because of their wide application, persistence in the environment, and bioaccumulation. PFCs associate with immunological disorders including asthma and attenuate immune responses to vaccines. The influence of PFCs on the immunological response to allergens during childhood is unknown. We report here that a major PFC, perfluorooctane sulfonate (PFOS), inactivates house dust mite (HDM) to dampen 5-wk-old, early weaned mice from developing HDM-induced allergic asthma. PFOS further attenuates the asthma protective effect of the microbial product lipopolysaccharide (LPS). We demonstrate that PFOS prevents desensitization of lung epithelia by LPS, thus abolishing the latter's protective effect. A close mechanistic study reveals that PFOS specifically binds the major HDM allergen Der p1 with high affinity as well as the lipid A moiety of LPS, leading to the inactivation of both antigens. Moreover, PFOS at physiological human (nanomolar) concentrations inactivates Der p1 from HDM and LPS in vitro, although higher doses did not cause further inactivation because of possible formation of PFOS aggregates. This PFOS-induced neutralization of LPS has been further validated in primary human cell models and extended to an in vivo bacterial infection mouse model. This study demonstrates that early life exposure of mice to a PFC blunts airway antigen bioactivity to modulate pulmonary inflammatory responses, which may adversely affect early pulmonary health.

Biomarkers of poly- and perfluoroalkyl substances (PFAS) in Sub-Arctic and Arctic communities in Canada

Polyfluoroalkyl substances and perfluoroalkyl substances (PFAS) are a family of anthropogenic chemicals that are used in food packaging, waterproof clothing, and firefighting foams for their water and oil resistant properties. Though levels of some PFAS appear to be decreasing in Canada's south, environmental levels have been increasing in the Arctic due to long-range transport. However, the implications of this on human exposures in sub-Arctic and Arctic populations in Canada have yet to be established. To address this data gap, human biomonitoring research was completed in Old Crow, Yukon, and the Dehcho region, Northwest Territories. Blood samples were collected from adults residing in seven northern First Nations and were analyzed by liquid chromatography mass spectrometry. A total of nine PFAS were quantified: perfluorooctanoic acid (PFOA), perfluorooctane sulphonic acid (PFOS), perfluorohexane sulphonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUdA), perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), and perfluorobutane sulphonic acid (PFBS). In the Dehcho (n = 124), five PFAS had a detection rate greater than 50% including PFOS, PFOA, PFHxS, PFNA, and PFDA. In addition to these PFAS, PFUdA was also detected in at least half of the samples collected in Old Crow (n = 54). Generally, male participants had higher concentrations of PFAS compared to female participants, and PFAS concentrations tended to increase with age. For most PFAS, Old Crow and Dehcho levels were similar or lower to those measured in the general Canadian population (as measured through the Canadian Health Measures Survey or CHMS) and other First Nations populations in Canada (as measured through the First Nations Biomonitoring Initiative or FNBI). The key exception to this was for PFNA which, relative to the CHMS (0.51 μg/L), was approximately 1.8 times higher in Old Crow (0.94 μg/L) and 2.8 times higher in Dehcho (1.42 μg/L) than observed in the general Canadian population. This project provides baseline PFAS levels for participating communities, improving understanding of human exposures to PFAS in Canada. Future research should investigate site-specific PFNA exposure sources and monitor temporal trends in these regions.