Association of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) with uric acid among adults with elevated community exposure to PFOA

Evaluation of the exposure to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) through drinking water and human risk assessment

In the present study, two most commonly used Perfluoroalkyl substances (PFASs), namely perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), were determined in 45 tap water samples from the city of Isfahan (Iran) by dispersive liquid-liquid extraction (DLLME) and liquid chromatography-mass spectrophotometry (LC-MS) analysis. Risk assessment was also performed to determine the risk to human health. The mean concentration of PFOA was 38.1 ± 26.4ng/L (min = 5.1 and max = 1056ng/L). The mean concentration of PFOS was 33.7 ± 25.09ng/L (min = 4.3 and max = 99.2ng/L). The combined concentrations of PFOA and PFOS were above the US-EPA advisory levels (70ng/L) in 48.8% of the samples. The distance between the sampling locations and the water treatment plant showed no significant correlation (p > 0.05). The results of the risk assessment showed that all calculated hazard quotients (HQ) and hazard indices (HI) are below 1, indicating that the risk to human health from exposure to PFOA and PFOS via drinking water in the city of Isfahan was not high for adults and children. These results indicate a significant contamination of Isfahan tap water by PFOA and PFOS of unknown origin. Further studies are needed on the Zayande-Roud River water as a supplier of Isfahan tap water and the efficiency of the water treatment plant and the role of the water distribution network in PFASs contamination of tap water.

Impact of PFOS Exposure on Murine Fetal Hematopoietic Stem Cells, Associated with Intrauterine Metabolic Perturbation

This study hypothesized that perfluorooctanesulfonate (PFOS) exposure disrupts maternal-fetal metabolism, affecting fetal liver hematopoietic stem cell (FL-HSC) development. Pregnant mice received PFOS (0.3 and 3 μg/g bw) and were sacrificed on gestation day 14.5. Metabolomic analysis of maternal plasma revealed disruptions in steroid hormone, purine, carbohydrate, and amino acid metabolism, which aligned with the enriched pathways in amniotic fluid (AF). FL analysis indicated increased purine metabolism and disrupted glucose and amino acid metabolism. FL exhibited higher levels of polyunsaturated fatty acids, glycolytic and TCA metabolites, and pro-inflammatory cytokine IL-23, crucial for hematopoiesis regulation. Transcriptomic analysis of FL-HSCs revealed disturbances in the PPAR signaling pathway, pyruvate metabolism, oxidative phosphorylation, and amino acid metabolism, correlating with FL metabolic changes. Metabolomic analysis indicated significant rises in glycerophospholipid and vitamin B6 metabolism related to HSC expansion and differentiation. Flow cytometric analysis confirmed increased HSC populations and progenitor activation for megakaryocyte, erythrocyte, and lymphocyte lineages. The CFU assay showed a significant increase in BFU-E and CFU-G, but a decrease in CFU-GM in FL-HSCs from the H-PFOS group, indicating altered differentiation potential. These findings provide for the first time insights into the effects of PFOS on maternal-fetal metabolism and fetal hematopoiesis, highlighting implications for pollution-affected immune functions.

Association of per- and polyfluoroalkyl substances with gout risk: a cross-sectional analysis of NHANES 2007-2018 data emphasizing mixture effects

Objective

This study examined associations between serum concentrations of per- and polyfluoroalkyl substances (PFASs) and gout risk in the U.S. adult population using the National Health and Nutrition Examination Survey (NHANES) 2007-2018 data. And assessing the potential intermediary effect of uric acid.

Methods

The study included 8,494 participants, with 385 having gout. Four PFAS compounds (PFOA, PFOS, PFHxS, PFNA) were measured. PFOS is the most prevalent PFAS in the environment, biota, and human tissues. It is rapidly absorbed and accumulates in the liver, kidneys, and blood, binding to serum albumin and low-density lipoprotein. PFOA is highly persistent in the body, mainly accumulating in the kidneys and liver through enterohepatic circulation, posing risks due to its difficulty in metabolism and excretion. PFHxS has the longest metabolic half-life in humans (7.3 years) and bioaccumulates in the endocrine, immune, nervous, and reproductive systems. PFNA is the second most detected PFAS in human serum after PFOS. It is more likely to accumulate and express toxicity in the reproductive organs, liver, and immune system compared to PFOS and PFOA. Multivariate logistic regression and weighted quantile sum regression were used to assess individual and mixture effects. Mediation analysis was conducted to estimate effect of uric acid.

Results

In fully adjusted model, the associations were nonsignificant, with PFOA showing a marginally positive association. Mixture analysis revealed a significant positive association with gout risk across all models. PFOS was the largest contributor to the mixture effect. Stronger associations were observed in old people and females. Sensitivity analyses confirmed the robustness of these findings. Mediation analysis indicated significant intermediary effect of uric acid in the associations of PFAS with risk of gout, with the mediated proportion ranging from 48 to 77%.

Conclusion

This study provides evidence for a potential link between PFAS exposure and gout risk, particularly when considering mixtures. While associations with individual PFASs are largely explained by demographic and lifestyle factors, the persistent association of mixtures with gout risk highlights the importance of considering combined exposures in environmental health research. Uric acid level plays a crucial intermediary effect.

Association between exposure to perfluoroalkyl and polyfluoroalkyl substances with estimated glomerular filtration rate: Mediating role of serum albumin

BACKGROUND

Previous studies have demonstrated perfluoroalkyl and polyfluoroalkyl substances (PFAS) impact renal function, with albumin playing dominant role in their transport and accumulation. However, the mediating role of albumin in PFAS-induced renal impairment and the identification of sensitive populations remain uninvestigated.

METHODS

This study included 9328 individuals from NHANES 1999-2018 with data on serum PFAS, creatinine, albumin, and covariates. The estimated glomerular filtration rate (eGFR) was calculated using standardized creatinine. Associations between perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA) with eGFR and the risk of decreased renal function (eGFR < 90 vs. eGFR ≥ 90) using linear and logistic regression, weighted quantile sum (WQS) regression, Bayesian kernel machine regression (BKMR), and restricted cubic spline (RCS) analyses. Subgroup analyses identified sensitive populations. Mediation analysis was performed to examine the mediating role of albumin. Comparative toxicology databases identified relevant genes for mechanistic exploration.

RESULTS

Ln-transformed PFOA (β = -1.91, 95 % CI: -2.82 to -1), PFOS (β = -1.48, 95 % CI: -2.19 to -0.78) and PFHxS (β = -0.94, 95 % CI: -1.65 to -0.23) were negatively correlated with eGFR. PFOA (aOR = 1.21, 95 % CI: 1.1-1.32), PFOS (aOR = 1.2, 95 % CI: 1.12-1.29), and PFHxS (aOR = 1.13, 95 % CI: 1.05-1.21) were positively correlated with the risk of decreased renal function. Subgroup analyses indicated that individuals ≤ 45 years, females and other races were more sensitive. Albumin mediated 18.2 %, 16.4 %, 29.8 %, and 18.7 % of the negative effects of PFOA, PFOS, PFHxS, and PFNA on eGFR, respectively. Functional enrichment analysis suggested PFAS impair renal function by affecting lipid metabolism and increasing oxidative stress.

CONCLUSIONS

PFAS exposure is negatively associated with eGFR and positively associated with the risk of decreased renal function, with albumin playing a partial mediating role.

Unveiling the Research Void: Exploring the Reproductive Effects of PFAS Compounds on Male Health

Per- and polyfluoroalkyl substances (PFAS) represent an emerging concern for male reproductive health. Epidemiological studies have reported associations between increased PFAS exposure and reduced semen quality parameters, lower sperm counts, and potential alterations in reproductive hormone levels. Toxicology research has revealed possible mechanisms including blood-testis barrier disruption, oxidative stress, interference with testicular cell function, and epigenetic changes. However, significant uncertainties remain regarding definitive exposure-response relationships, developmental windows of heightened vulnerability, combined mixture effects, and causality interpretation, given limitations inherent to observational studies. Ongoing investigation of short-chain and replacement PFAS compounds is also critically needed. Additionally, directly connecting the mechanistic insights from animal models to human fertility impacts remains challenging. While controlled toxicology studies have described pathways by which PFAS could impair cellular functioning in the testes, uncertainty persists in extrapolating these experimental effects to real-world human exposures and sperm parameter declines reported epidemiologically. Overall, current findings suggest PFAS may contribute to declining male reproductive function, but additional clarification through well-designed longitudinal cohort studies integrated with mechanistic animal work is still warranted to confirm exposure-fertility links across a range of PFAS types and inform evidence-based public health mitigation strategies.

Exploring the sources, occurrence, transformation, toxicity, monitoring, and remediation strategies of per- and polyfluoroalkyl substances: a review

Per- and polyfluoroalkyl substances (PFAS), a class of man-made chemicals, possess unique properties that have rendered them indispensable in various industries and consumer goods. However, their extensive use and persistence in the environment have raised concerns about their potential repercussions on human health and the ecosystem. This review provides insights into the sources, occurrence, transformation, impacts, fate, monitoring, and remediation strategies for PFAS. Once released into the environment, these chemicals undergo intricate transformation processes, such as degradation, bioaccumulation, and biomagnification, which result in their far-reaching distribution and persistence. Their chemical stability results in persistent pollution, with far-reaching ecological and human health implications. Remediation strategies for PFAS are still in their infancy, and researchers are exploring innovative and sustainable methods for treating contaminated environments. Promising technologies such as adsorption, biodegradation, and electrochemical oxidation have shown the potential to remove PFAS from contaminated sites, yet the search for more efficient and sustainable solutions continues. In conclusion, this review emphasizes the urgent need for continued research and innovation to address the global environmental challenge posed by PFAS. As we move forward, it is imperative to prioritize sustainable solutions that minimize the detrimental consequences of these substances on human health and the environment.

Association between per- and polyfluoroalkyl substances and hyperuricemia: sex-specific analysis

Perfluoroalkyl and polyfluoroalkyl(PFAS) substances are the most common environmental pollutants, which has an inconsistent association with hyperuricemia across different populations. This study explored the relationship between hyperuricemia and different gender PFAS and PFAS mixtures, using data from two cycles of the NHANES from 2015-2018. Weighted logistic regression results showed that the correlation between individual PFAS and hyperuricemia was significant only in men. Compared to the reference quartile, the fourth quartile of n-PFOA increased the risk of hyperuricemia in men (OR: 2.79, 95% CI: 1.50, 5.18). The Qgcomp model results showed that each quartile increase in the serum concentration of PFAS mixtures was associated with an increased likelihood of hyperuricemia in the total population, with odds ratios (OR) for men and women being 1.74 (95% CI: 1.26, 2.40), and 2.04 (95% CI: 1.35, 3.16), respectively. we concluded that PFAS might increase the risk of hyperuricemia in adults.

Associations of Serum Per- and Polyfluoroalkyl Substances with Hyperuricemia in Adults: A Nationwide Cross-Sectional Study

There has been widespread concern about the health hazards of per- and polyfluoroalkyl substances (PFAS), which may be the risk factor for hyperuricemia with evidence still insufficient in the general population in China. Here, we conducted a nationwide study involving 9,580 adults aged 18 years or older from 2017 to 2018, measured serum concentrations of uric acid and PFAS (PFOA, PFOS, 6:2 Cl-PFESA, PFNA, PFHxS) in participants, to assess the associations of individual PFAS with hyperuricemia, and estimated a joint effect of PFAS mixtures. We found positive associations of higher serum PFAS with elevated odds of hyperuricemia in Chinese adults, with the greatest contribution from PFOA (69.37%). The nonmonotonic dose-response (NMDR) relationships were observed for 6:2 Cl-PFESA and PFHxS with hyperuricemia. Participants with less marine fish consumption, overweight, and obesity may be the sensitive groups to the effects of PFAS on hyperuricemia. We highlight the potential health hazards of legacy long-chain PFAS (PFOA) once again because of the higher weights of joint effects. This study also provides more evidence about the NMDR relationships in PFAS with hyperuricemia and emphasizes a theoretical basis for public health planning to reduce the health hazards of PFAS in sensitive groups.

Kidney function decline mediates the adverse effects of per- and poly-fluoroalkyl substances (PFAS) on uric acid levels and hyperuricemia risk

Previous studies indicated per- and poly-fluoroalkyl substances (PFAS) were related to uric acid and hyperuricemia risk, but evidence for the exposure-response (E-R) curves and combined effect of PFAS mixture is limited. Moreover, the potential mediation effect of kidney function was not assessed. Hence, we conducted a national cross-sectional study involving 13,979 US adults in NHANES 2003-2018 to examine the associations of serum PFAS with uric acid and hyperuricemia risk, and the mediation effects of kidney function. Generalized linear models and E-R curves showed positive associations of individual PFAS with uric acid and hyperuricemia risk, and nearly linear E-R curves indicated no safe threshold for PFAS. Weighted quantile sum regression found positive associations of PFAS mixture with uric acid and hyperuricemia risk, and PFOA was the dominant contributor to the adverse effect of PFAS on uric acid and hyperuricemia risk. Causal mediation analysis indicated significant mediation effects of kidney function decline in the associations of PFAS with uric acid and hyperuricemia risk, with the mediated proportion ranging from 19 % to 57 %. Our findings suggested that PFAS, especially PFOA, may cause increased uric acid and hyperuricemia risk increase even at low levels, and kidney function decline plays a crucial mediation effect.

Emerging organic contaminants in drinking water systems: Human intake, emerging health risks, and future research directions

Few earlier reviews on emerging organic contaminants (EOCs) in drinking water systems (DWS) focused on their detection, behaviour, removal and fate. Reviews on multiple exposure pathways, human intake estimates, and health risks including toxicokinetics, and toxicodynamics of EOCs in DWS are scarce. This review presents recent advances in human intake and health risks of EOCs in DWS. First, an overview of the evidence showing that DWS harbours a wide range of EOCs is presented. Multiple human exposure to EOCs occurs via ingestion of drinking water and beverages, inhalation and dermal pathways are discussed. A potential novel exposure may occur via the intravenous route in dialysis fluids. Analysis of global data on pharmaceutical pollution in rivers showed that the cumulative concentrations (μg L-1) of pharmaceuticals (mean ± standard error of the mean) were statistically more than two times significantly higher (p = 0.011) in South America (11.68 ± 5.29), Asia (9.97 ± 3.33), Africa (9.48 ± 2.81) and East Europe (8.09 ± 4.35) than in high-income regions (2.58 ± 0.48). Maximum cumulative concentrations of pharmaceuticals (μg L-1) decreased in the order; Asia (70.7) had the highest value followed by South America (68.8), Africa (51.3), East Europe (32.0) and high-income regions (17.1) had the least concentration. The corresponding human intake via ingestion of untreated river water was also significantly higher in low- and middle-income regions than in their high-income counterparts. For each region, the daily intake of pharmaceuticals was highest in infants, followed by children and then adults. A critique of the human health hazards, including toxicokinetics and toxicodynamics of EOCs is presented. Emerging health hazards of EOCs in DWS include; (1) long-term latent and intergenerational effects, (2) the interactive health effects of EOC mixtures, (3) the challenges of multifinality and equifinality, and (4) the Developmental Origins of Health and Disease hypothesis. Finally, research needs on human health hazards of EOCs in DWS are presented.

Perfluoroalkyl/Polyfluoroalkyl Substances: Links to Cardiovascular Disease Risk

Conservative estimates by the World Health Organization suggest that at least a quarter of global cardiovascular diseases are attributable to environmental exposures. Associations between air pollution and cardiovascular risk have garnered the most headlines and are strong, but less attention has been paid to other omnipresent toxicants in our ecosystem. Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are man-made chemicals that are extensively used in industrial and consumer products worldwide and in aqueous film-forming foam utilized in firefighting. As such, our exposure to PFAS is essentially ubiquitous. Given the long half-lives of these degradation-resistant chemicals, virtually, all people are carrying a body burden of PFAS. Health concerns related to PFAS are growing such that the National Academies of Sciences, Engineering and Medicine has recommended standards for clinical follow-up of individuals with high PFAS blood levels, including prioritizing screening for dyslipidemia. The link between PFAS and dyslipidemia has been extensively investigated, and evidence for associations is compelling. However, dyslipidemia is not the only cardiovascular risk factor with which PFAS is associated. Here, we review the epidemiological evidence for links between PFAS of concern identified by the National Academies of Sciences, Engineering and Medicine and risk factors for cardiovascular disease, including overweight/obesity, glucose intolerance, hypertension, dyslipidemia, and hyperuricemia. Moreover, we review the potential connections of PFAS with vascular disease and atherosclerosis. While observational data support associations between the National Academies of Sciences, Engineering and Medicine PFAS and selected cardiac risk factors, additional research is needed to establish causation and better understand how exposure to PFAS leads to the development of these conditions.

An integrated assessment of ecological and human health risks of per- and polyfluoroalkyl substances through toxicity prediction approaches

Per- and polyfluoroalkyl substances (PFAS) are also known as "forever chemicals" due to their persistence and ubiquitous environmental distribution. This review aims to summarize the global PFAS distribution in surface water and identify its ecological and human risks through integrated assessment. Moreover, it provides a holistic insight into the studies highlighting the human biomonitoring and toxicological screening of PFAS in freshwater and marine species using quantitative structure-activity relationship (QSAR) based models. Literature showed that PFOA and PFOS were the most prevalent chemicals found in surface water. The highest PFAS levels were reported in the US, China, and Australia. The TEST model showed relatively low LC50 of PFDA and PFOS for Pimephales promelas (0.36 and 0.91 mg/L) and high bioaccumulation factors (518 and 921), revealing an elevated associated toxicity. The risk quotients (RQs) values for P. promelas and Daphnia magna were found to be 269 and 23.7 for PFOS. Studies confirmed that long-chain PFAS such as PFOS and PFOA undergo bioaccumulation in aquatic organisms and induce toxicological effects such as oxidative stress, transgenerational epigenetic effects, disturbed genetic and enzymatic responses, perturbed immune system, hepatotoxicity, neurobehavioral toxicity, altered genetic and enzymatic responses, and metabolism abnormalities. Human biomonitoring studies found the highest PFOS, PFOA, and PFHxS levels in urine, cerebrospinal fluid, and serum samples. Further, long-chain PFOA and PFOS exposure create severe health implications such as hyperuricemia, reduced birth weight, and immunotoxicity in humans. Molecular docking analysis revealed that short-chain PFBS (-11.84 Kcal/mol) and long-chain PFUnDA (-10.53 Kcal/mol) displayed the strongest binding interactions with human serum albumin protein. Lastly, research challenges and future perspectives for PFAS toxicological implications were also discussed, which helps to mitigate associated pollution and ecological risks.

A metabolomic investigation of serum perfluorooctane sulfonate and perfluorooctanoate

BACKGROUND

Exposures to perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), environmentally persistent chemicals detectable in the blood of most Americans, have been associated with several health outcomes. To offer insight into their possible biologic effects, we evaluated the metabolomic correlates of circulating PFOS and PFOA among 3,647 participants in eight nested case-control serum metabolomic profiling studies from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

METHODS

Metabolomic profiling was conducted by Metabolon Inc., using ultra high-performance liquid chromatography/tandem accurate mass spectrometry. We conducted study-specific multivariable linear regression analyses estimating the associations of metabolite levels with levels of PFOS or PFOA. For metabolites measured in at least 3 of 8 nested case-control studies, random effects meta-analysis was used to summarize study-specific results (1,038 metabolites in PFOS analyses and 1,100 in PFOA analyses).

RESULTS

The meta-analysis identified 51 and 38 metabolites associated with PFOS and PFOA, respectively, at a Bonferroni-corrected significance level (4.8x10-5 and 4.6x10-5, respectively). For both PFOS and PFOA, the most common types of associated metabolites were lipids (sphingolipids, fatty acid metabolites) and xenobiotics (xanthine metabolites, chemicals). Positive associations were commonly observed with lipid metabolites sphingomyelin (d18:1/18:0) (P = 2.0x10-10 and 2.0x10-8, respectively), 3-carboxy-4-methyl-5-pentyl-2-furanpropionate (P = 2.7x10-15, 1.1x10-17), and lignoceroylcarnitine (C24) (P = 2.6x10-8, 6.2x10-6). The strongest positive associations were observed for chemicals 3,5-dichloro-2,6-dihydroxybenzoic acid (P = 3.0x10-112 and 6.8x10-13, respectively) and 3-bromo-5-chloro-2,6-dihydroxybenzoic acid (P = 1.6x10-14, 2.3x10-6). Other metabolites positively associated with PFOS included D-glucose (carbohydrate), carotene diol (vitamin A metabolism), and L-alpha-aminobutyric acid (glutathione metabolism), while uric acid (purine metabolite) was positively associated with PFOA. PFOS associations were consistent even after adjusting for PFOA as a covariate, while PFOA associations were greatly attenuated with PFOS adjustment.

CONCLUSIONS

In this large metabolomic study, we observed robust positive associations with PFOS for several molecules. Further investigation of these metabolites may offer insight into PFOS-related biologic effects.

Occurrence of per- and polyfluoroalkyl substances in aquatic environments and their removal by advanced oxidation processes

Per- and polyfluoroalkyl substances (PFAS), one of the main categories of emerging contaminants, are a family of fluorinated organic compounds of anthropogenic origin. PFAS can endanger the environment and human health because of their wide application in industries, long-term persistence, unique properties, and bioaccumulation potential. This study sought to explain the accumulation of different PFAS in water bodies. In aquatic environments, PFAS concentrations range extensively from <0.03 (groundwater; Melbourne, Australia) to 51,000 ng/L (Groundwater, Sweden). Additionally, bioaccumulation of PFAS in fish and water biota has been stated to range from 0.2 (Burbot, Lake Vättern, Sweden) to 13,900 ng/g (Bluegill samples, U.S.). Recently, studies have focused on PFAS removal from aqueous solutions; one promising technique is advanced oxidation processes (AOPs), including microwaves, ultrasound, ozonation, photocatalysis, UV, electrochemical oxidation, the Fenton process, and hydrogen peroxide-based and sulfate radical-based systems. The removal efficiency of PFAS ranges from 3% (for MW) to 100% for UV/sulfate radical as a hybrid reactor. Therefore, a hybrid reactor can be used to efficiently degrade and remove PFAS. Developing novel, efficient, cost-effective, and sustainable AOPs for PFAS degradation in water treatment systems is a critical area of research.

Thermal kinetics of PFAS and precursors in soil: Experiment and surface simulation in temperature-time plane

Per- and polyfluoroalkyl substances (PFAS) are chemically and thermally stable due to the presence of carbon-fluorine (C-F) bond in their molecular structures, hence have been previously formulated as firefighting ingredients. During the firefighting process, however, owing to the high temperature, PFAS can be potentially degraded, particularly for PFAS precursors that contain non-C-F bonds, which is studied herein by exposing PFAS-contaminated soil in a muffle furnace oven. Different temperatures and time intervals are applied to the real soil sample to mimic the firing process and to evaluate the degradation and conversion of PFAS. This thermal treatment can not only degrade precursors (e.g. 6:2 fluorotelomer sulphonate), but also degrade perfluoroalkyl carboxylates (PFCA, e.g. perfluorooctanoic acid PFOA) and perfluoroalkyl sulfonates (PFSA, e.g. perfluorooctane sulfonate PFOS). The concentration dependence of the PFAS on temperature and time is fitted using a 2D Gaussian surface to simulate the complex thermal kinetic, and to compare with the traditional approach such as thermogravimetric analysis (TGA) (1D dependence on temperature only). The 2D simulation can directly visualise the thermal kinetic of individual or sum PFAS in the complex temperature-time plane, which depends on the sample background and particularly on the coexist PFAS precursors. Overall, this study provides a simple approach to monitor and optimise the thermal treatment of the PFAS-contaminated soil.

Electrochemical-based approaches for the treatment of forever chemicals: Removal of perfluoroalkyl and polyfluoroalkyl substances (PFAS) from wastewater

Electrochemical based approaches for the treatment of recalcitrant water borne pollutants are known to exhibit superior function in terms of efficiency and rate of treatment. Considering the stability of Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are designated as forever chemicals, which generating from various industrial activities. PFAS are contaminating the environment in small concentrations, yet exhibit severe environmental and health impacts. Electro-oxidation (EO) is a recent development that treats PFAS, in which different reactive species generates at anode due to oxidative reaction and reductive reactions at the cathode. Compared to water and wastewater treatment methods those being implemented, electrochemical approaches demonstrate superior function against PFAS. EO completely mineralizes (almost 100 %) non-biodegradable organic matter and eliminate some of the inorganic species, which proven as a robust and versatile technology. Electrode materials, electrolyte concentration pH and the current density applying for electrochemical processes determine the treatment efficiency. EO along with electrocoagulation (EC) treats PFAS along with other pollutants from variety of industries showed highest degradation of 7.69 mmol/g of PFAS. Integrated approach with other processes was found to exhibit improved efficiency in treating PFAS using several electrodes boron-doped diamond (BDD), zinc, titanium and lead based with efficiency the range of 64 to 97 %.

Perfluorooctanoic acid (PFOA) exposure in relation to the kidneys: A review of current available literature

Perfluorooctanoic acid is an artificial and non-degradable chemical. It is widely used due to its stable nature. It can enter the human body through food, drinking water, inhalation of household dust and contact with products containing perfluorooctanoic acid. It accumulates in the human body, causing potential harmful effects on human health. Based on the biodegradability and bioaccumulation of perfluorooctanoic acid in the human body, there are increasing concerns about the adverse effects of perfluorooctanoic acid exposure on kidneys. Research shows that kidney is the main accumulation organ of Perfluorooctanoic acid, and Perfluorooctanoic acid can cause nephrotoxicity and produce adverse effects on kidney function, but the exact mechanism is still unknown. In this review, we summarize the relationship between Perfluorooctanoic acid exposure and kidney health, evaluate risks more clearly, and provide a theoretical basis for subsequent research.

Double Filtration Plasmapheresis with Polyvinyl Alcohol-Based Membrane Lowers Serum Inflammation and Toxins in Patients with Hyperlipidemia

Hyperlipidemia is increasing in prevalence and is highly correlated with cardiovascular disease (CVD). Lipid-lowering medications prevent CVD but may not be suitable when the side effects are intolerable or hypercholesterolemia is too severe. Double-filtration plasmapheresis (DF) has shown its therapeutic effect on hyperlipidemia, but its side effects are not yet known. We enrolled 45 adults with hyperlipidemia in our study. The sera before and two weeks after DF were evaluated, and we also analyzed perfluorochemicals to see if DF could remove these lipophilic toxins. After DF, all lipid profile components (total cholesterol, triglycerides, high-density lipoprotein [HDL], and low-density lipoprotein [LDL]) had significantly decreased. Leukocyte counts increased while platelet levels decreased, which may have been caused by the puncture wound from DF and consumption of platelets during the process. As for uremic toxins and inflammation, levels of C-reactive protein, uric acid, and alanine transaminase (ALT) all decreased, which may be related to the removal of serum perfluorooctane sulfonate (PFOS) and improvement of renal function. The total cholesterol/HDL ratio and triglycerides were significantly higher in the diabetes mellitus (DM) group at baseline but did not significantly differ after DF. In conclusion, DF showed potential for improving inflammation and removing serum lipids and PFOS in adults with hyperlipidemia.

Perfluoroalkyl substances (PFASs) are substrates of the renal human organic anion transporter 4 (OAT4)

Poly- and perfluoroalkyl substances (PFASs) are omnipresent in the environment and have been shown to accumulate in humans. Most PFASs are not biotransformed in animals and humans, so that elimination is largely dependent on non-metabolic clearance via bile and urine. Accumulation of certain PFASs in humans may relate to their reabsorption from the pre-urine by transporter proteins in the proximal tubules of the kidney, such as URAT1 and OAT4. The present study assessed the in vitro transport of 7 PFASs (PFHpA, PFOA, PFNA, PFDA, PFBS, PFHxS and PFOS) applying URAT1- or OAT4-transfected human embryonic kidney (HEK) cells. Virtually no transport of PFASs could be measured in URAT1-transfected HEK cells. All PFASs, except PFBS, showed clear uptake in OAT4-transfected HEK cells. In addition, these in vitro results were further supported by in silico docking and molecular dynamic simulation studies assessing transporter-ligand interactions. Information on OAT4-mediated transport may provide insight into the accumulation potential of PFASs in humans, but other kinetic aspects may play a role and should also be taken into account. Quantitative information on all relevant kinetic processes should be integrated in physiologically based kinetic (PBK) models, to predict congener-specific accumulation of PFASs in humans in a more accurate manner.

Association between exposure to perfluoroalkyl substances and uric acid in Chinese adults

BACKGROUND

A growing body of evidence suggests the deleterious effects of perfluoroalkyl substances (PFASs) on kidney, but little is known on the association between PFASs joint exposure and uric acid.

METHODS

Serum PFASs concentrations were measured in 661 participants recruited from Tianjin, China using liquid chromatography/mass spectrometry. The associations of single PFASs exposure with uric acid levels and hyperuricemia were assessed using multivariable linear and logistic regression models, respectively. Restricted cubic spline models were established to investigate the dose-response relationships between PFASs concentrations and uric acid levels. Bayesian Kernel Machine Regression (BKMR) model with a hierarchical variable selection was performed to assess the joint effect of PFASs on uric acid.

RESULTS

Potassium perfluoro-1-octanesulfonate (PFOS) and perfluoro-n-octanoic acid (PFOA) were the dominated contributors with median concentrations of 16.80 ng/ml and 9.42 ng/ml, respectively. Increased PFOA concentration (per log₂-unit) was associated with elevated uric acid level (β = 0.088, 95% CI: 0.033-0.143) and higher risk of hyperuricemia (OR = 1.134, 95% CI: 1.006-1.289). Conversely, the estimated change of uric acid associated with log₂-unit increment in perfluoro-n-decanoic acid (PFDA) was -0.081 mg/dL (95% CI: -0.154, -0.009). A significant linear dose-response pattern was found between log₂-transformed PFOA concentration and uric acid level. BKMR analyses indicated a non-significant overall effect of PFASs mixture on uric acid.

CONCLUSIONS

Significant associations between PFOA and PFDA and uric acid, and between PFOA and hyperuricemia were found in the single-pollutant models, but the joint effect of PFASs mixture on uric acid was not observed in the BKMR model, which provided new insights in regulation policies and risk assessment of PFASs.

Associations of exposure to perfluoroalkyl substances with serum uric acid change and hyperuricemia among Chinese women: Results from a longitudinal study

BACKGROUND

Cross-sectional studies have reported associations of perfluorooctanoic acid (PFOA) with concurrent serum uric acid (UA) levels. However, the prospective associations of other commonly detected perfluoroalkyl substances (PFASs) with serum UA and hyperuricemia remain unclear.

METHODS

A total of 654 females from the Dongfeng-Tongji cohort, who were followed up from 2008 to 2018, were included in this study. We measured their baseline plasma concentrations of six PFASs [including perfluorooctane sulfonic acid (PFOS), PFOA, perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), and perfluoroheptanoic acid (PFHpA)], as well as their serum UA levels at both baseline and follow-up visits. General linear and logistic regression models were constructed to explore the associations of each PFAS with annual change of serum UA and incident hyperuricemia. Mixture effects of PFASs were further assessed by using the quantile g-computation approach.

RESULTS

Compared to participants with low PFNA exposure (≤50^th), those with high PFNA exposure (>75^th) had significantly increased annual increment of serum UA [β(95%CI) = 2.58 (0.60, 4.55)]. No significant associations of PFOS, PFOA, PFDA, PFHxS, or PFHpA with serum UA change were observed. Besides, females with high PFOA or PFHpA (>75^th) exposure had higher incident risk of hyperuricemia than those with low exposure (<50^th) [OR (95%CI) = 1.94 (1.00, 3.76) and 1.86 (1.03, 3.36), respectively]. No significant associations of PFOS, PFNA, PFDA, and PFHxS with hyperuricemia risk were observed. Quantile g-computation approach didn't find significant effects of PFAS co-exposure on serum UA change or hyperuricemia incidence.

CONCLUSIONS

Our findings suggested exposure to PFASs as a risk factor for hyperuricemia and shed light on hyperuricemia prevention for elderly females.

Associations between serum perfluoroalkyl acid (PFAA) concentrations and health related biomarkers in firefighters

Firefighters who used aqueous film forming foam in the past have experienced elevated exposures to perfluoroalkyl acids (PFAAs). The objective of this study was to examine the associations between clinical chemistry endpoints and serum concentrations of perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS) and perfluorooctane sulfonate (PFOS) in firefighters. Multiple linear regression was used to assess relationships between PFAA serum concentrations and biochemical markers for cardiovascular disease, kidney-, liver- and thyroid function, in a cross-sectional survey of 783 firefighters with elevated levels of PFHxS, PFHpS and PFOS in relation to the most recently reported levels in the general Australian population. Linear logistic regression was used to assess the odds ratios for selected self-reported health outcomes. Repeated measures linear mixed models were further used to assess relationships between PFAAs and biomarkers for cardiovascular disease and kidney function longitudinally in a subset of the firefighters (n = 130) where serum measurements were available from two timepoints, five years apart. In the cross-sectional analysis, higher levels of all PFAAs were significantly associated with higher levels of biomarkers for cardiovascular disease (total-cholesterol, and LDL-cholesterol). For example, doubling in PFOS serum concentration were associated with increases in total cholesterol (β:0.111, 95% confidence interval (95%CI): 0.026, 0.195 mmol/L) and LDL-cholesterol (β: 0.104, 95%CI:0.03, 0.178 mmol/L). Doubling in PFOA concentration, despite not being elevated in the study population, were additionally positively associated with kidney function marker urate (e.g., β: 0.010, 95%CI; 0.004, 0.016 mmol/L) and thyroid function marker TSH (e.g., β: 0.087, 95%CI: 0.014, 0.161 mIU/L). PFAAs were not associated with any assessed self-reported health conditions. No significant relationships were observed in the longitudinal analysis. Findings support previous studies, particularly on the association between PFAAs and serum lipids.

Target analysis and suspect screening of per- and polyfluoroalkyl substances in paired samples of maternal serum, umbilical cord serum, and placenta near fluorochemical plants in Fuxin, China

The levels of legacy per- and polyfluoroalkyl substances (PFASs) have been growing in the environmental matrices and blood of residents living around the fluorochemical industrial park (FIP) in Fuxin of China over the past decade. Although some recent studies have reported occurrence of novel PFAS alternatives in biotic and abiotic matrices near fluorochemical facilities worldwide, little is known about novel PFAS congeners in maternal sera, umbilical cord sera, and placentas from the female residents close to the FIP and their related health risks. In this study, 50 paired samples of maternal and cord serum as well as placenta were derived from Fuxin pregnant women at delivery, and 21 target analytes of legacy PFASs in all the samples were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), revealing that PFBS, PFBA, and PFOA were the dominant PFAS contaminants observed in the whole samples. Based upon the suspect screening through high-resolution mass spectrometry (HRMS), 49 novel PFASs assigned to 11 classes were further identified in the Fuxin samples, of which, 20 novel congeners in 4 classes were reported in human blood and placentas for the first time. Moreover, the coefficients for mother-placenta transfer (R_m/p), placenta-newborn transfer (R_p/n), and mother-newborn transfer (R_m/n) of legacy PFASs could be calculated with median values of 1.7, 1.1, and 2.0, respectively, and R_m/p, R_p/n, and R_m/n for each novel PFAS identified were also estimated with the median values of 0.9, 1.2, and 0.8 individually. Accordingly, novel PFASs contributed 90% of all the legacy and novel PFASs in maternal sera and even occupied 96% of the whole PFASs in both placentas and cord sera. In addition, significant associations were determined among the neonate birth outcomes and serum concentrations of thyroid hormone, sex hormone, and glucocorticoid, together with the levels of certain legacy and novel PFASs in cord sera.

Photodegradation of per- and polyfluoroalkyl substances in water: A review of fundamentals and applications

Per- and polyfluoroalkyl substances (PFAS) are persistent, mobile, and toxic chemicals that are hazardous to human health and the environment. Several countries, including the United States, plan to set an enforceable maximum contamination level for certain PFAS compounds in drinking water sources. Among the available treatment options, photocatalytic treatment is promising for PFAS degradation and mineralization in the aqueous solution. In this review, recent advances in the abatement of PFAS from water using photo-oxidation and photo-reduction are systematically reviewed. Degradation mechanisms of PFAS by photo-oxidation involving the holes (h_vb⁺) and oxidative radicals and photo-reduction using the electrons (e_cb^-) and hydrated electrons (e_aq^-) are integrated. The recent development of innovative heterogeneous photocatalysts and photolysis systems for enhanced degradation of PFAS is highlighted. Photodegradation mechanisms of alternative compounds, such as hexafluoropropylene oxide dimer acid (GenX) and chlorinated polyfluorinated ether sulfonate (F-53B), are also critically evaluated. This paper concludes by identifying major knowledge gaps and some of the challenges that lie ahead in the scalability and adaptability issues of photocatalysis for natural water treatment. Development made in photocatalysts design and system optimization forges a path toward sustainable treatment of PFAS-contaminated water through photodegradation technologies.

Characterization of Potential Adverse Outcome Pathways Related to Metabolic Outcomes and Exposure to Per- and Polyfluoroalkyl Substances Using Artificial Intelligence

Human exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with numerous adverse health effects, depending on various factors such as the conditions of exposure (dose/concentration, duration, route of exposure, etc.) and characteristics associated with the exposed target (e.g., age, sex, ethnicity, health status, and genetic predisposition). The biological mechanisms by which PFAS might affect systems are largely unknown. To support the risk assessment process, AOP-helpFinder, a new artificial intelligence tool, was used to rapidly and systematically explore all available published information in the PubMed database. The aim was to identify existing associations between PFAS and metabolic health outcomes that may be relevant to support building adverse outcome pathways (AOPs). The collected information was manually organized to investigate linkages between PFAS exposures and metabolic health outcomes, including dyslipidemia, hypertension, insulin resistance, and obesity. Links between PFAS exposure and events from the existing metabolic-related AOPs were also retrieved. In conclusion, by analyzing dispersed information from the literature, we could identify some associations between PFAS exposure and components of existing AOPs. Additionally, we identified some linkages between PFAS exposure and metabolic outcomes for which only sparse information is available or which are not yet present in the AOP-wiki database that could be addressed in future research.

Assessing explicit models of per- and polyfluoroalkyl substances adsorption on anion exchange resins by rapid small-scale column tests

Managing per- and polyfluoroalkyl substance (PFAS) contamination has gained worldwide attention due to their ubiquitous occurrence in water systems. Anion exchange resins (AERs) have been proven effective in removing both long-chain and short-chain PFASs. In this study, an explicit model was developed to describe the breakthrough behavior of an individual PFAS as a single solute onto anion exchange resin in a column filtration process. The model was further modified to predict the breakthrough curve of co-existing PFASs on AER in multi-solute systems by incorporating a separation factor describing the competitive adsorption and a blockage factor describing the loss of adsorption sites. Rapid small-scale column tests (RSSCTs) were performed with six AERs of various properties and three model PFASs in both single- and multi-solutes systems. The breakthrough behaviors of RSSCTs for both single- and multi-solute systems were found adequately described by the models developed in this study. The experiments and accompanied model simulations reveal some important relationships between the AER performance and the properties of both the AERs and the PFASs.

Official health communications are failing PFAS-contaminated communities

BACKGROUND

Environmental health agencies are critical sources of information for communities affected by chemical contamination. Impacted residents and their healthcare providers often turn to federal and state agency webpages, fact sheets, and other documents to weigh exposure risks and interventions.

MAIN BODY

This commentary briefly reviews scientific evidence concerning per- and polyfluoroalkyl substances (PFAS) for health outcomes that concern members of affected communities and that have compelling or substantial yet differing degree of scientific evidence. It then features official documents in their own language to illustrate communication gaps, as well as divergence from scientific evidence and from best health communication practice. We found official health communications mostly do not distinguish between the needs of heavily contaminated communities characterized by high body burdens and the larger population with ubiquitous but substantially smaller exposures. Most health communications do not distinguish levels of evidence for health outcomes and overemphasize uncertainty, dismissing legitimate reasons for concern in affected communities. Critically, few emphasize helpful approaches to interventions. We also provide examples that can be templates for improvement.

CONCLUSIONS

Immediate action should be undertaken to review and improve official health communications intended to inform the public and health providers about the risks of PFAS exposure and guide community and medical decisions.

Gestational Diabetes Mellitus: The Crosslink among Inflammation, Nitroxidative Stress, Intestinal Microbiota and Alternative Therapies

Gestational diabetes mellitus (GDM) is characterized by a set of metabolic complications arising from adaptive failures to the pregnancy period. Estimates point to a prevalence of 3 to 15% of pregnancies. Its etiology includes intrinsic and extrinsic aspects of the progenitress, which may contribute to the pathophysiogenesis of GDM. Recently, researchers have identified that inflammation, oxidative stress, and the gut microbiota participate in the development of the disease, with potentially harmful effects on the health of the maternal-fetal binomial, in the short and long terms. In this context, alternative therapies were investigated from two perspectives: the modulation of the intestinal microbiota, with probiotics and prebiotics, and the use of natural products with antioxidant and anti-inflammatory properties, which may mitigate the endogenous processes of the GDM, favoring the health of the mother and her offspring, and in a future perspective, alleviating this critical public health problem.

Metabolome-wide association study of serum exogenous chemical residues in a cohort with 5 major chronic diseases

BACKGROUND

Chronic diseases have become main killers affecting the health of human, and environmental pollution is a major health risk factor that cannot be ignored. It has been reported that exogenous chemical residues including pesticides, herbicides, fungicides, veterinary drugs and persistent organic pollutants are associated with chronic diseases. However, the evidence for their relationship is equivocal and the underlying mechanisms are unclear.

OBJECTIVES

We aim to investigate the linkages between serum exogenous chemical residues and 5 main chronic diseases including obesity, hyperuricemia, hypertension, diabetes and dyslipidemia, and further reveal the metabolic perturbations of chronic diseases related to exogenous chemical residue exposure, then gain potential mechanism insight at the metabolic level.

METHODS

LC-MS-based targeted and nontargeted methods were respectively performed to quantify exogenous chemical residues and acquire metabolic profiling of 496 serum samples from chronic disease patients. Non-parametric test, correlation and regression analyses were carried out to investigate the association between exogenous chemical residues and chronic diseases. Metabolome-wide association study combined with the meeting-in-the-middle strategy and mediation analysis was performed to reveal and explain exposure-related metabolic disturbances and their risk to chronic diseases.

RESULTS

In the association analysis of 106 serum exogenous chemical residues and 5 chronic diseases, positive associations of serum perfluoroalkyl substances (PFASs) with hyperuricemia were discovered while other associations were not significant. 240 exposure markers of PFASs and 84 disease markers of hyperuricemia were found, and 47 of them were overlapped and considered as putative effective markers. Serum uric acid, amino acids, cholesterol, carnitines, fatty acids, glycerides, glycerophospholipids, ceramides, and a part of sphingolipids were positively correlated with PFASs and associated with increased risk for hyperuricemia. Creatine, creatinine, glyceryl monooleate, phosphatidylcholine 36:6, phosphatidylethanolamine 40:6, cholesterol and sphingolipid 36:1;2O were significant markers which mediated the associations of the residues with hyperuricemia.

CONCLUSIONS

Our study demonstrated a significantly positive association between PFASs exposure and hyperuricemia. The most significant metabolic abnormality was lipid metabolism which not only was positively associated with PFASs, but also increased the risk of hyperuricemia.

Per- and polyfluoroalkyl substance (PFAS) exposure, maternal metabolomic perturbation, and fetal growth in African American women: A meet-in-the-middle approach

BACKGROUND

Prenatal exposures to per- and polyfluoroalkyl substances (PFAS) have been linked to reduced fetal growth. However, the detailed molecular mechanisms remain largely unknown. This study aims to investigate biological pathways and intermediate biomarkers underlying the association between serum PFAS and fetal growth using high-resolution metabolomics in a cohort of pregnant African American women in the Atlanta area, Georgia.

METHODS

Serum perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) measurements and untargeted serum metabolomics profiling were conducted in 313 pregnant African American women at 8-14 weeks gestation. Multiple linear regression models were applied to assess the associations of PFAS with birth weight and small-for-gestational age (SGA) birth. A high-resolution metabolomics workflow including metabolome-wide association study, pathway enrichment analysis, and chemical annotation and confirmation with a meet-in-the-middle approach was performed to characterize the biological pathways and intermediate biomarkers of the PFAS-fetal growth relationship.

RESULTS

Each log2-unit increase in serum PFNA concentration was significantly associated with higher odds of SGA birth (OR = 1.32, 95% CI 1.07, 1.63); similar but borderline significant associations were found in PFOA (OR = 1.20, 95% CI 0.94, 1.49) with SGA. Among 25,516 metabolic features extracted from the serum samples, we successfully annotated and confirmed 10 overlapping metabolites associated with both PFAS and fetal growth endpoints, including glycine, taurine, uric acid, ferulic acid, 2-hexyl-3-phenyl-2-propenal, unsaturated fatty acid C18:1, androgenic hormone conjugate, parent bile acid, and bile acid-glycine conjugate. Also, we identified 21 overlapping metabolic pathways from pathway enrichment analyses. These overlapping metabolites and pathways were closely related to amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism perturbations.

CONCLUSION

In this cohort of pregnant African American women, higher serum concentrations of PFOA and PFNA were associated with reduced fetal growth. Perturbations of biological pathways involved in amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism were associated with PFAS exposures and reduced fetal growth, and uric acid was shown to be a potential intermediate biomarker. Our results provide opportunities for future studies to develop early detection and intervention for PFAS-induced fetal growth restriction.

Perfluoroalkyl substances (PFASs) exposure and kidney damage: Causal interpretation using the US 2003-2018 National Health and Nutrition Examination Survey (NHANES) datasets

INTRODUCTION

The objective of this study was to validate the hypothesis that increased serum concentrations of perfluoroalkyl substances (PFASs) cause kidney damage. A causal interpretative study was designed using the US 2003-2018 National Health and Nutrition Examination Survey (NHANES) datasets.

METHODS

Three statistical models, including multivariable linear regression, generalized additive model, and regression discontinuity model (RDM), were applied to the US 2003-2018 NHANES datasets to evaluate the causal relationship between the four PFAS agents and estimated glomerular filtration rate (eGFR). Directed acyclic graphs were plotted for a more valid causal inference.

RESULTS AND DISCUSSION

In the RDM, when the natural logarithm of each PFAS agent increases by 1 ng/mL after each cut-off value, eGFR decreased 4.63 mL/min/1.73 m² for perfluorooctanoic acid, 3.42 mL/min/1.73 m² for perfluorooctane sulfonic acid, 2.37 mL/min/1.73 m² for perfluorohexane sulfonic acid, and 2.87 mL/min/1.73 m² for perfluorononanoic acid. The possibility of reverse causation that increased serum PFAS concentration is the consequence of reduced eGFR, not the cause, was low, and an additional adjustment of potential confounders was not needed.

CONCLUSION

This study contributes to the understanding of PFAS-induced kidney damage. Further longitudinal epidemiological and toxicological studies are recommended.

Dietary Exposure of Japanese Quail (Coturnix japonica) to Perfluorooctane Sulfonate (PFOS) and a Legacy Aqueous Film-Forming Foam (AFFF) Containing PFOS: Effects on Reproduction and Chick Survivability and Growth

Effects of perfluorooctane sulfonate (PFOS) and a legacy aqueous film-forming foam (AFFF) containing 91% PFOS (AFFF PFOS) on reproduction, chick survivability, and growth of Japanese quail (Coturnix japonica) were determined. Day-old Japanese quail were administered PFOS or AFFF PFOS at 6 dietary concentrations ranging from 0 to 21 mg kg^-1 feed for a total of 20 wk. At the age of 4 wk, 16 male/female pairs per treatment were assigned to cages, and egg laying was induced by the age of 10 wk. Eggs were collected daily, set weekly, and incubated for 18 d for the following 10 wk. Hatchlings were fed uncontaminated feed for 2 wk and euthanized to collect blood and liver. After 10 wk of egg collection, adults were euthanized to collect blood, liver, and kidneys. Significantly increased myofiber numbers in the liver and glomerular sclerosis in the kidneys of adults indicated damage at greater doses. Perfluorooctane sulfonate or AFFF PFOS did not significantly affect egg production; however, hatchability was decreased at the highest PFOS dose. The no-observed-adverse-effect levels for chick survivability, considered the critical effect, were 4.1 mg PFOS kg feed^-1 (0.55 mg kg body wt^-1  d^-1 ) and 5.0 mg AFFF PFOS kg feed^-1 (0.66 mg kg body wt^-1  d^-1 ), resulting in calculated average toxicity reference values of 0.25 mg kg feed^-1 and 0.034 mg kg body weight^-1  d^-1 . Environ Toxicol Chem 2021;40:2521-2537. © 2020 SETAC.

Effect of granular activated carbon and other porous materials on thermal decomposition of per- and polyfluoroalkyl substances: Mechanisms and implications for water purification

Thermal treatment is routinely used to reactivate the spent granular activated carbon (GAC) from water purification facilities. It is also an integral part of sewage sludge treatment and municipal solid waste management. This study presents a detailed investigation of the fate of per- and polyfluoroalkyl substances (PFAS) and one PFAS alternative (GenX) in thermal processes, focusing on the effect of GAC. We demonstrate that the thermolysis of perfluoroalkyl carboxylic acids (PFCAs), including perfluorooctanoic acid (PFOA), and GenX can occur at temperatures of 150‒200 °C. Three temperature zones were discovered for PFOA, including a stable and nonvolatile zone (≤90 °C), a phase-transfer and thermal decomposition zone (90‒400 °C), and a fast decomposition zone (≥400 °C). The thermal decomposition began with the homolysis of a C‒C bond next to the carboxyl group of PFCAs, which formed unstable perfluoroalkyl radicals. Dual decomposition pathways seem to exist. The addition of a highly porous adsorbent, such as GAC or a copolymer resin, compressed the intermediate sublimation zone of PFCAs, changed their thermal decomposition pathways, and increased the decomposition rate constant by up to 150-fold at 250 °C. The results indicate that the observed thermal decomposition acceleration was linked to the adsorption of gas-phase PFCA molecules on GAC. The presence of non-activated charcoals/biochars with a low affinity for PFOA did not accelerate its thermal decomposition, suggesting that the π electron-rich, polyaromatic surface of charcoal/GAC played an insignificant role compared to the adsorbent's porosity. Overall, the results indicate that (1) substantial decomposition of PFCAs and GenX during conventional thermal GAC/sludge/waste treatment is very likely, and (2) the presence or addition of GAC or other highly porous materials can accelerate thermal PFAS decomposition and alter decomposition pathways.

Why is elevation of serum cholesterol associated with exposure to perfluoroalkyl substances (PFAS) in humans? A workshop report on potential mechanisms

Serum concentrations of cholesterol are positively correlated with exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in humans. The associated change in cholesterol is small across a broad range of exposure to PFOA and PFOS. Animal studies generally have not indicated a mechanism that would account for the association in humans. The extent to which the relationship is causal is an open question. Nonetheless, the association is of particular importance because increased serum cholesterol has been considered as an endpoint to derive a point of departure in at least one recent risk assessment. To gain insight into potential mechanisms for the association, both causal and non-causal, an expert workshop was held Oct 31 and Nov 1, 2019 to discuss relevant data and propose new studies. In this report, we summarize the relevant background data, the discussion among the attendees, and their recommendations for further research.

Perfluoroalkyl substance excretion: Effects of organic anion-inhibiting and resin-binding drugs in a community setting

BACKGROUND

Longer serum half-lives of perfluoroalkyl substances (PFAS) in humans compared to other species has been attributed to differences in the activity of organic anion transporters (OAT).

METHODS

Among 56,175 adult participants in the community-based C8 Health Project, 23 subjects were taking the uricosuric OAT-inhibitor probenecid, and 36 subjects were taking the bile acid sequestrant cholestyramine. In regression models of log transformed serum PFAS, medication effects were estimated in terms of mean ratios, adjusting for age, gender, BMI, estimated glomerular filtration rate (eGFR) and water-district of residence.

RESULTS

Probenecid was associated with modest, but not statistically significant increases in serum PFAS concentrations. In contrast, cholestyramine significantly lowered serum PFAS concentrations, notably for perfluorooctane sulfonic acid (PFOS).

CONCLUSIONS

The effectiveness of cholestyramine in a community setting supports the importance of gastrointestinal physiology for PFAS excretion kinetics, especially for PFOS. We did not find clear evidence that probenecid, an inhibitor of OAT, affects PFAS clearance.

Per- and polyfluoroalkyl substances and calcifications of the coronary and aortic arteries in adults with prediabetes: Results from the diabetes prevention program outcomes study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are endocrine disrupting chemicals that have been associated with cardiovascular risk factors including elevated body weight and hypercholesterolemia. Therefore, PFAS may contribute to the development of atherosclerosis and cardiovascular disease (CVD). However, no previous study has evaluated associations between PFAS exposure and arterial calcification.

METHODS AND RESULTS

This study used data from 666 prediabetic adults enrolled in the Diabetes Prevention Program trial who had six PFAS quantified in plasma at baseline and two years after randomization, as well as measurements of coronary artery calcium (CAC) and ascending (AsAC) and descending (DAC) thoracic aortic calcification 13-14 years after baseline. We performed multinomial regression to test associations between PFAS and CAC categorized according to Agatston score [low (<10), moderate (11-400) and severe (>400)]. We used logistic regression to assess associations between PFAS and presence of AsAC and DAC. We adjusted models for baseline sex, age, BMI, race/ethnicity, cigarette smoking, education, treatment assignment (placebo or lifestyle intervention), and statin use. PFAS concentrations were similar to national means; 53.9% of participants had CAC > 11, 7.7% had AsAC, and 42.6% had DAC. Each doubling of the mean sum of plasma concentrations of linear and branched isomers of perfluorooctane sulfonic acid (PFOS) was associated with 1.49-fold greater odds (95% CI: 1.01, 2.21) of severe versus low CAC. This association was driven mainly by the linear (n-PFOS) isomer [1.54 (95% CI: 1.05, 2.25) greater odds of severe versus low CAC]. Each doubling of mean plasma N-ethyl-perfluorooctane sulfonamido acetic acid concentration was associated with greater odds of CAC in a dose-dependent manner [OR = 1.26 (95% CI:1.08, 1.47) for moderate CAC and OR = 1.37 (95% CI:1.07, 1.74) for severe CAC, compared to low CAC)]. Mean plasma PFOS and n-PFOS were also associated with greater odds of AsAC [OR = 1.67 (95% CI:1.10, 2.54) and OR = 1.70 (95% CI:1.13, 2.56), respectively], but not DAC. Other PFAS were not associated with outcomes.

CONCLUSIONS

Prediabetic adults with higher plasma concentrations of select PFAS had higher risk of coronary and thoracic aorta calcification. PFAS exposure may be a risk factor for adverse cardiovascular health among high-risk populations.

Associations between serum isomers of perfluoroalkyl acids and metabolic syndrome in adults: Isomers of C8 Health Project in China

BACKGROUND

Exposure to perfluoroalkyl acids (PFAAs) is known to be associated with metabolic disorders. However, whether PFAAs isomers are associated with metabolic syndrome (MetS) still remains unknown.

OBJECTIVES

To explore the associations between serum PFAAs isomers and MetS.

METHODS

We recruited 1,501 adults from a cross-sectional study, the "Isomers of C8 Health Project in China" to investigate the associations between PFAAs isomers and MetS. A total of 20 PFAAs including the isomers of PFOS and PFOA were detected. Logistic regression models and restricted cubic spline models were used to evaluate the relationship of serum PFAAs isomers exposure with MetS and its components as well after adjusting for covariates.

RESULTS

The MetS prevalence in our study was 43.0%. The serum levels of both PFOS and PFOA isomers were higher in participants with MetS than that with non-MetS (p < 0.05). We found positive associations for per natural log-transformed ng/mL of branched perfluorooctane sulfonate (br-PFOS) (odds ratio (OR) = 1.18, 95% confidence interval (CI): 1.01, 1.38)) linear perfluoronanoic acid (n-PFOA) (OR = 1.35, 95% CI: 1.16, 1.58) and perfluoro-6-methylpheptanoic acid (6 m-PFOA) (OR = 1.32, 95% CI: 1.11, 1.57) with higher odds of MetS after covariates adjustment, while null association was observed for linear isomers of PFOS (OR = 1.09, 95% CI: 0.94, 1.25). We found a nonlinear dose-response relationship with a "threshold" effect in serum br-PFOS isomers with MetS, in which the odds of MetS increased quickly with increasing serum br-PFOS isomers under low exposure (p for nonlinearity = 0.030).

CONCLUSION

We report new evidence of associations between PFAAs isomers and MetS and the nonlinearity of dose-response relationship with br-PFOS isomers. Our findings indicate that more attention is needed to pay on the nonlinearity of dose-response relationship when investigate the association of PFAAs isomers with human health.

Per- and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

Reports of environmental and human health impacts of per- and polyfluoroalkyl substances (PFAS) have greatly increased in the peer-reviewed literature. The goals of the present review are to assess the state of the science regarding toxicological effects of PFAS and to develop strategies for advancing knowledge on the health effects of this large family of chemicals. Currently, much of the toxicity data available for PFAS are for a handful of chemicals, primarily legacy PFAS such as perfluorooctanoic acid and perfluorooctane sulfonate. Epidemiological studies have revealed associations between exposure to specific PFAS and a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer. Concordance with experimental animal data exists for many of these effects. However, information on modes of action and adverse outcome pathways must be expanded, and profound differences in PFAS toxicokinetic properties must be considered in understanding differences in responses between the sexes and among species and life stages. With many health effects noted for a relatively few example compounds and hundreds of other PFAS in commerce lacking toxicity data, more contemporary and high-throughput approaches such as read-across, molecular dynamics, and protein modeling are proposed to accelerate the development of toxicity information on emerging and legacy PFAS, individually and as mixtures. In addition, an appropriate degree of precaution, given what is already known from the PFAS examples noted, may be needed to protect human health. Environ Toxicol Chem 2021;40:606-630. © 2020 SETAC.

Human Biomonitoring (HBM)-I values for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) - Description, derivation and discussion

In 2016, the German Human Biomonitoring Commission (HBM-C) published a statement on its decision to develop HBM-I values for Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS) (Bundesgesundheitsbl 2016, 59:1364 DOI 10.1007/s00103-016-2437-1). The HBM-I value corresponds to the concentration of a substance in a human biological material below which no adverse health effects are expected, according to current knowledge and assessment by the HBM-C, and, consequently, there is no need for action. Evidence for associations between PFOA- and PFOS-body burden and health outcomes was found for fertility and pregnancy, weights of newborns at birth, lipid metabolism, immunity, sex hormones and age at puberty/menarche, thyroid hormones, onset of menopause as well as uric acid metabolism. Significant contrasts were reported for human blood plasma concentrations between 1 and 10 ng PFOA/mL, and 1-15 ng PFOS/mL, respectively. Within the reported ranges, the HBM-C has decided to set the HBM-I-values at 2 ng PFOA/mL and 5 ng PFOS/mL blood plasma. The underlying pathomechanisms do not appear to be sufficiently clarified to provide an unambiguous explanation of the effects observed. Consistency of toxicological and epidemiological data has been considered. The available data do not indicate an unequivocal proof of a genotoxicity of PFOA and PFOS.

Per- and polyfluoroalkyl substance mixtures and gestational weight gain among mothers in the Health Outcomes and Measures of the Environment study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent chemicals commonly used in the production of household and consumer goods. While exposure to PFAS has been associated with greater adiposity in children and adults, less is known about associations with gestational weight gain (GWG).

METHODS

We quantified using mass spectrometry perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorohexanesulfanoate (PFHxS) and perfluorononanoate (PFNA) in maternal serum from 18 ± 5 weeks' gestation (mean ± standard deviation (std)) in a prospective pregnancy and birth cohort (2003-2006, Cincinnati, Ohio) (n = 277). After abstracting weight data from medical records, we calculated GWG from 16 ± 2 weeks' gestation (mean ± std) to the measured weight at the last visit or at delivery, rate of weight gain in the 2nd and 3rd trimesters (GWR), and total weight gain z-scores standardized for gestational age at delivery and pre-pregnancy BMI. We investigated covariate-adjusted associations between individual PFAS using multivariable linear regression; we assessed potential effect measure modification (EMM) by overweight/obese status (pre-pregnancy BMI<25 kg/m2 v. ≥25 kg/m2). Using weighted quantile sum regression, we assessed the combined influence of these four PFAS on GWG and GWR.

RESULTS

Each doubling in serum concentrations of PFOA, PFOS, and PFNA was associated with a small increase in GWG (range 0.5-0.8 lbs) and GWR (range 0.03-0.05 lbs/week) among all women. The association of PFNA with GWG was stronger among women with BMI≥25 kg/m2 (β = 2.6 lbs; 95% CI:-0.8, 6.0) than those with BMI<25 kg/m2 (β = -1.0 lbs; 95% CI:-3.8, 1.8; p-EMM = 0.10). We observed associations close to the null between PFAS and z-scores and between the PFAS exposure index (a combined summary measure) and the outcomes.

CONCLUSION

Although there were consistent small increases in gestational weight gain with increasing PFOA, PFOS, and PFNA serum concentrations in this cohort, the associations were imprecise. Additional investigation of the association of PFAS with GWG in other cohorts would be informative and could consider pre-pregnancy BMI as a potential modifier.

Metabolic Signatures of the Exposome-Quantifying the Impact of Exposure to Environmental Chemicals on Human Health

Human health and well-being are intricately linked to environmental quality. Environmental exposures can have lifelong consequences. In particular, exposures during the vulnerable fetal or early development period can affect structure, physiology and metabolism, causing potential adverse, often permanent, health effects at any point in life. External exposures, such as the “chemical exposome” (exposures to environmental chemicals), affect the host’s metabolism and immune system, which, in turn, mediate the risk of various diseases. Linking such exposures to adverse outcomes, via intermediate phenotypes such as the metabolome, is one of the central themes of exposome research. Much progress has been made in this line of research, including addressing some key challenges such as analytical coverage of the exposome and metabolome, as well as the integration of heterogeneous, multi-omics data. There is strong evidence that chemical exposures have a marked impact on the metabolome, associating with specific disease risks. Herein, we review recent progress in the field of exposome research as related to human health as well as selected metabolic and autoimmune diseases, with specific emphasis on the impacts of chemical exposures on the host metabolome.

Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs): Occurrence and Association with Serum Biochemical Parameters in Residents Living Near a Fluorochemical Plant in China

Although perfluoroalkyl ether carboxylic (PFECAs) and sulfonic acids (PFESAs) have been widely detected in environmental matrices, their occurrence in humans and impact on human health remains insufficiently understood. Here, we report on 13 PFECAs and PFESAs in 977 sera samples collected from residents living near a fluorochemical plant in Shandong, China. The sum concentration of these emerging PFECAs accounted for 13% of the total PFASs in the serum of the participants, with the frequent detection of several PFECAs (>95%) (PFMOAA, PFO4DA, and PFO5DoDA at median concentrations of 12.91, 0.142, and 0.987 ng/mL, respectively) and PFESAs (98.7%) (Nafion byproduct 2 at a median concentration of 0.097 ng/mL). Serum PFMOAA, PFO5DoDA, and 6:2 Cl-PFESA levels were significantly higher in males than in females. Positive relationships were observed between age and PFMOAA, 6:2 Cl-PFESA, and H-PFMO2OSA levels, whereas HFPO-TA and PFO5DoDA serum concentrations in the 0-40-year age group were lower than that in the >40-year age group. Furthermore, multivariate linear regression models and sensitivity analyses showed positive associations among PFO5DoDA levels, elevated lipid parameters (cholesterol, low-density lipoprotein cholesterol, and triglycerides), liver function markers (albumin levels and alanine transaminase, aspartate aminotransferase, and glutamyl transpeptidase activities), and uric acid levels. Thus, our results suggest potential health risks from exposure to novel PFESAs and PFECAs (especially PFO5DoDA).

Perfluoroalkyl acids, hyperuricemia and gout in adults: Analyses of NHANES 2009-2014

BACKGROUND

Previous studies have reported a positive association of perfluoralkyl acids (PFAAs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), with hyperuricemia. The objective of the study is to investigate whether there is an association between concurrent serum levels of several PFAAs and gout, serum uric acid (SUA) or hyperuricemia in the U.S. adult population as represented by the National Health and Nutrition Examination Survey (NHANES) 2009-2014 sample (n = 4917). The PFAAs investigated include PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonic acid (PFHxS) and PFOS.

METHODS

This cross-sectional study used multivariate logistic regressions to analyze the association of single PFAAs with hyperuricemia and self-reported gout; the association with SUA was analyzed by multivariate linear regression. Analyses were adjusted for race/ethnicity, age, sex, education, alcohol consumption, smoking, serum cotinine, BMI, diabetes, hypertension, chronic kidney disease, and SUA (for gout only).

RESULTS

Higher quartile values of serum PFOA and PFHxS were associated with increased odds of self-reported gout. There was a positive association of SUA with increased levels of PFOA, PFNA, PFOS, PFHxS and PFDA. Higher quartile values of PFOA, PFNA, and PFHxS were associated with higher odds of hyperuricemia.

CONCLUSIONS

In this population-based cross-sectional analysis, we found an association between selected PFAAs and self-reported gout. We also confirmed previous reports of an association between several PFAAs and hyperuricemia. Our study suggests that exposure to PFAAs may be a risk factor for hyperuricemia and gout.

Association between exposure to perfluoroalkyl substances and metabolic syndrome and related outcomes among older residents living near a Science Park in Taiwan

Perfluoroalkyl substances (PFASs) are an emerging class of artificial environmental chemicals that have multiple potentially harmful effects on health. The largest Science Park in Taiwan discharges wastewater containing PFASs into the Keya River, and a high concentration of PFASs has been found in this river and its aquatic creatures. We conducted a cross-sectional study from 2016 to 2017 of 397 subjects aged 55-75 years living near the river and evaluated the association of PFASs with metabolic syndrome and related outcomes. The results indicated that perfluorooctane sulfonate (PFOS) levels were positively associated with serum low-density lipoprotein (LDL) levels (P for trend = 0.03) and that perfluorononanoic acid (PFNA) and PFOS levels were positively correlated with uric acid levels (P for trend = 0.03 and 0.03). Perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA) levels were negatively associated with serum triglyceride levels (P for trend = 0.014 and < 0.01). After excluding lipid-lowering drug users, the association between certain PFAS levels and the LDL level was significantly enhanced, but the downward trends of serum triglyceride levels were weakened. When stratified by sex, PFNA (P for trend <0.01), perfluorohexanesulfonate (PFHxS) (P for trend <0.01), and PFOS (P for trend <0.01) showed positive associations with the uric acid level only among males. In conclusion, our results showed that associations were consistently null between PFASs and metabolic syndrome. PFAS levels were associated with serum lipids, and lipid-lowering drugs may interfere with this relationship. Certain PFASs were found to be positively associated with uric acid levels, especially in males. Further studies are warranted to clarify the causal relationships.

Bioaccumulation of perfluoroalkyl substances in greenhouse vegetables with long-term groundwater irrigation near fluorochemical plants in Fuxin, China

The levels of perfluoroalkyl substances (PFASs) have been growing progressively in the groundwater beneath a fluorochemical industrial park (FIP) in Fuxin of China recently, however, little information is available about whether long-term irrigation with local groundwater could have a potential effect on the bioaccumulation of PFASs in greenhouse vegetables near the FIP. In the present study, groundwater, soil, and vegetable samples were collected from Fuxin with five sampling campaigns during a period of 40 days, and ten target analytes of PFASs in all the samples were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). As the dominant PFAS contaminants, perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) in groundwater samples were determined with the maximum levels of 2.47 and 32.4 μg L^-1, respectively. Furthermore, perfluorobutanoic acid (PFBA), PFOA, and PFBS were the major PFASs in greenhouse samples of soil (up to 6.1, 6.8, and 46 ng g dry weight (dw)^-1), tomato (up to 87, 1.7, and 13 ng g dw^-1), and cucumber (up to 63, 2.6, and 15 ng g dw^-1), which were significantly correlated with those in groundwater samples, indicating PFAS contaminations could be introduced into soil and vegetables in the greenhouse through long-term groundwater irrigation. In addition, all the levels of three main PFAS analytes in soil and vegetables presented an overall increasing trend over the period of vegetable growth. The bioaccumulation efficiencies for PFAS contaminants from soil to vegetables were negatively associated with the carbon chain length in PFASs. According to the reference dose (RfD) for PFBA, PFOA, and PFBS from the Minnesota Department of Health (MDH), daily intakes of those three analytes by rural residents in Fuxin were lower than the respective RfD via consumption of greenhouse tomatoes and cucumbers so far. However, long-term surveillance would be focused on greenhouse vegetables near the Fuxin FIP to prevent potential health risks of local residents from increasing PFAS contaminations.

Perfluoroalkyl substances exposure and hearing impairment in US adults

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widely applied in consumer and industrial products such as nonstick cookware, waterproof clothing, food packaging materials, and fire-fighting foams. These "forever chemicals" are hypothesized to impact neurobehavioral functions. Yet no previous study has explored the role of PFAS on audiometrically determined hearing impairment (HI).

OBJECTIVES

To investigate the associations of serum concentrations of perfluoroalkyl substances with low-frequency HI (LFHI) and high-frequency HI (HFHI) in US adults.

METHODS

We evaluated the cross-sectional associations in 2371 adults aged 20-69 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2003-2004, 2011-2012 and 2015-2016; and 449 adults aged ≥70 years from NHANES 2005-2006 and 2009-2010. Serum concentrations of perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), were measured using solid-phase extraction coupled to High Performance Liquid Chromatography-Turbo Ion Spray ionization-tandem Mass Spectrometry. LFHI was defined as a pure-tone average (PTA) of thresholds across 0.5-1-2 kHz >25 dB; HFHI defined as a PTA across 3-4-6 kHz >25 dB in the worse ear. Survey-weighted logistic regression models were used to compute odds ratios (ORs) and 95% confidence intervals (CIs) with adjustment for age, age-squared, sex, race/ethnicity, education, poverty-to-income ratio, body mass index, smoking status, exposures to occupational, recreational and firearm noises, and NHANES cycles.

RESULTS

There were no significant associations when perfluoroalkyl variables were fitted as a linear (log-transformed) term. However, statistically significant associations of HFHI with PFNA (OR = 1.70, 95% CI: 1.13-2.56) and PFDA (OR = 1.75, 95% CI: 1.00-3.05) were observed when comparing participants with serum concentrations ≥90th vs. <90th percentiles of PFNA (90th percentile = 1.8 ng/mL) and PFDA (90th percentile = 0.5 ng/mL), respectively, in adults aged 20-69 years. No significant associations were observed for other compounds in adults aged 20-69 years and for all compounds in adults ≥70 years.

CONCLUSIONS

Our study does not provide strong evidence to support the ototoxicity of PFAS exposure. Non-linear threshold dose-response associations between serum concentrations of PFNA and PFDA and HFHI need further investigation.

In Vivo Generation of PFOA, PFOS, and Other Compounds from Cationic and Zwitterionic Per- and Polyfluoroalkyl Substances in a Terrestrial Invertebrate (Lumbricus terrestris)

Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are two environmentally persistent per- and polyfluoroalkyl substances (PFAS) that have been detected globally in human tissues and fluids. As part of a project investigating the indirect sources of PFOA/PFOS in the environment and engineered systems, this study is concerned with the mechanisms leading to their in vivo generation in terrestrial invertebrates. We demonstrate here the formation of PFOA and PFOS in earthworms (Lumbricus terrestris) from a group of four zwitterionic/cationic polyfluoroalkyl amides and sulfonamides. In bioaccumulation tests, the zwitterionic PFAS compounds were metabolized within 10 days to PFOA/PFOS at yields of 3.4-20.8 mol % by day 21 and several infrequently reported PFAS species for which chemical structures were determined using high-resolution mass spectrometry. Cationic PFAS, on the other hand, were found to be much less metabolizable in terms of the number (n = 2) and yields (0.9-5.1 mol %) of metabolites. Peak-shaped bioaccumulation profiles were frequently observed for the studied PFAS. Residual zwitterionic/cationic PFAS in earthworms were detected at the end of the elimination phase, indicating that not all zwitterionic/cationic PFAS molecules in vivo are available for enzymatic degradation. Finally, the relative importance of different exposure routes (i.e., waterborne and dietary exposure) was investigated.

Removal of perfluoroalkanesulfonic acids (PFSAs) from synthetic and natural groundwater by electrocoagulation

Severe contaminations of perfluoroalkanesulfonic acids (PFSAs) existed in the natural groundwater beneath a fluorochemical industrial park (FIP) in Fuxin of China. In the present study, systematic researches were performed to determine the best conditions of efficient treatment for 1 mg L^-1 of PFSAs in the synthetic groundwater samples with the periodically reverse electrocoagulation (PREC) using the Al-Zn electrodes. Based upon the orthogonal experiments, the removal efficiencies of perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) could reach 87.4%, 95.6%, and 100%, respectively, within the initial 10 min, under the optimal conditions of voltage at 12.0 V, pH at 7.0, and stirring speed at 400 rpm. In addition, the optimized PREC technique was further applied to remove the PFSA contaminations from the natural groundwater samples of the Fuxin FIP, subsequently generating the removal efficiencies of three target PFSA analytes in the range between 59.0% and 100% at 60 min. Moreover, the SEM-EDS analyses showed the hydroxide flocs formed during the process of PREC treatment had clear characteristics of floc aggregates, with the major constituents of O, Al, C, N, Zn, and F elements. As a result, long-chain PFHxS and PFOS tended to be eliminated completely from the natural groundwater by their absorptions on the Al-Zn hydroxide flocs, potentially because of their higher hydrophobicity compared with short-chain PFBS.

Suitability of Remediated PFAS-Affected Soil in Cement Pastes and Mortars

Australia and many other parts of the world face issues of contamination in groundwater and soils by per- and poly-fluoroalkyl substances (PFAS). While the pyrolytic treatment of contaminated soils can destroy PFAS, the resulting heat-treated soils currently have limited applications. The purpose of this study was to demonstrate the usefulness of remediated soils in concrete applications. Using heat-treated soil as a fine aggregate, with a composition and particle size distribution similar to that of traditional concrete sands, proved to be a straightforward process. In such situations, complete fine aggregate replacement could be achieved with minimal loss of compressive strength. At high fine aggregate replacement (≥ 60%), a wetting agent was required for maintaining adequate workability. When using the heat-treated soil as a supplementary cementitious material, the initial mineralogy, the temperature of the heat-treatment and the post-treatment storage (i.e., keeping the soil dry) were found to be key factors. For cement mortars where minimal strength loss is desired, up to 15% of cement can be replaced, but up to 45% replacement can be achieved if moderate strengths are acceptable. This study successfully demonstrates that commercially heat-treated remediated soils can serve as supplementary cementitious materials or to replace fine aggregates in concrete applications.