Distribution of perfluorooctane sulfonate isomers and predicted risk of thyroid hormonal perturbation in drinking water

Occurrence of per- and polyfluoroalkyl substances in drinking water in China and health risk assessment based on a probabilistic approach

Per- and polyfluoroalkyl substances (PFASs) raise concerns due to their widespread distribution, persistence, and toxicity to humans. Current studies lack the use of exposure parameters for Chinese populations and probabilistic risk assessment (PRA) to assess health risks of PFASs. To provide a scientific basis for the standards of PFASs in drinking water in China, data on concentrations of nine PFASs in 649 drinking water samples were collected from China through literature review. The highest concentration of PFASs was 17.41 ± 20.06 ng/L for perfluorobutyric acid (PFBA). Higher concentrations of PFASs were found in the southeastern coastal and in Sichuan Province. The probability of exceeding the standardized limits for drinking water for PFOA and PFOS was 2.71 % and 0.91 %. PRA and deterministic risk assessment (DRA) were used to assess non-carcinogenic risks in different age groups and provinces. Health risks of PFASs from oral exposure notably exceeded dermal contact. The Hazard Quotient (HQ) for oral exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) exceeded the acceptable level with a certain probability. The non-carcinogenic risk of exposure to PFASs in drinking water was negligible for the majority of the Chinese population. The study indicates that China should increase research on limits of PFASs in drinking water to reduce the health risks.

Isomer of per- and polyfluoroalkyl substances and red blood cell indices in adults: The Isomers of C8 Health Project in China

This study aimed to explore the isomer-specific, sex-specific, and joint associations of PFAS and red blood cell indices. We used data of 1,238 adults from the Isomers of C8 Health Project in China. Associations of PFAS isomers and red blood cell indices were explored using multiple linear regression models, Bayesian Kernel Machine Regression models and subgroup analysis across sex. We found that serum concentration of linear (n-) and branched (Br-) isomers of perfluorooctane sulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) were significantly associated with red blood cell indices in single-pollutant models, with stronger associations observed for n-PFHxS than Br-PFHxS, in women than in men. For instance, the estimated percentage change in hemoglobin concentration for n-PFHxS (3.65%; 95% CI: 2.95%, 4.34%) was larger than that for Br-PFHxS (0.96%; 95% CI: 0.52%, 1.40%). The estimated percentage change in red blood cell count for n-PFHxS in women (2.55%; 95% CI: 1.81%, 3.28%) was significantly higher than that in men (0.12%; 95% CI: -1.04%, 1.29%) (Pinter < 0.001). Similarly, sex-specific positive association of PFAS mixture and outcomes was observed. Therefore, the structure, susceptive population, and joint effect of PFAS isomers should be taken into consideration when evaluating the health risk of chemicals.

Pressure of different level PFOS on aerobic granule sludge: Insights on performance, AGS structure, community succession, and microbial interaction responses

Perfluorooctane sulfonic acid (PFOS) has received much attention due to its potential environmental risks. However, the response of aerobic granular sludge (AGS) to PFOS exposure, particularly the microbial interactions, remains unclear. In this study, we investigated the particle structure of AGS, pollutant removal performance, community succession, and microbial interaction in the AGS system under different PFOS concentrations (0.1 and 1 mg/L). The mass balance showed that PFOS was mainly removed by adsorption with a removal rate of >85 %. PFOS caused some particles to break up and decreased the average particle size from 3.37 mm to 2.64 mm. It also significantly decreased the total nitrogen and total phosphorus removal rates, which was consistent with the deterioration of microbial activity, such as denitrification rate (25 % inhibition), phosphorus uptake rate (73.19 % inhibition), and phosphorus release rate (73.33 % inhibition). PFOS promoted the secretion of extracellular polymer (EPS) in AGS, especially proteins, leading to poor particle hydrophobicity. The network analysis illustrated that PFOS slowed down the information transfer between microorganisms, and increased the competition between them, which may be responsible for the deterioration of the system performance. Connections related to rare species accounted for >75 % of the network, suggesting that rare species have an indispensable role in community information exchange. In addition, rare species acted as seed banks for microorganisms, and under PFOS stress, they transformed into keystone species, which could contribute to system stabilization. This study provides new insights into the effects of PFOS on microbial interactions in AGS systems and the roles of rare species in the AGS microbial community.

The Need for Testing Isomer Profiles of Perfluoroalkyl Substances to Evaluate Treatment Processes

Many environmentally relevant poly-/perfluoroalkyl substances (PFASs) including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) exist in different isomeric (branched and linear) forms in the natural environment. The isomeric distribution of PFASs in the environment and source waters is largely controlled by the source of contamination and varying physicochemical properties imparted by their structural differences. For example, branched isomers of PFOS are relatively more reactive and less sorptive compared to the linear analogue. As a result, the removal of branched and linear PFASs during water treatment can vary, and thus the isomeric distribution in source waters can influence the overall efficiency of the treatment process. In this paper, we highlight the need to consider the isomeric distribution of PFASs in contaminated matrices while designing appropriate remediation strategies. We additionally summarize the known occurrence and variation in the physicochemical properties of PFAS isomers influencing their detection, fate, toxicokinetics, and treatment efficiency.

Exposure to per- and polyfluoroalkyl substances as a risk factor for gestational diabetes mellitus through interference with glucose homeostasis

Per- and polyfluoroalkyl substances (PFASs) are hypothesized to trigger gestational diabetes mellitus (GDM) through modulation of glucose metabolism. However, studies investigating links between joint PFASs to GDM are limited and led to discrepant conclusions. This study included 171 women with GDM development in pregnancy and 169 healthy controls from Hangzhou, China between October 2020 and September 2021. By using the solid-phase extraction (SPE)-ultra performance liquid chromatography-tandem-mass-spectrometry (UPLC/MS-MS), 15 PFASs were detected to be widely distributed in maternal serum, with highest median concentrations of 7.43, 4.23, and 3.64 ng/mL for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonates (6:2 Cl-PFESA). Multivariable logistic regressions suggested that the adjusted odds ratios (ORs) with 95% confidence intervals (CI) of GDM for second and highest tertiles of PFOA were 2.57 (1.24, 4.86), p = 0.001 and 1.98 (1.06, 3.65), p = 0.023. Compared with the reference tertile, the ORs of GDM were also significantly increased at the highest tertile of perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoA), PFOS and 6:2Cl-PFESA. Multiple linear regressions further indicated that exposure to these PFASs congeners were positively associated with continuous glycemic outcomes of fasting blood glucose (FBG), 1-h, and 2-h glucose after 75 g oral glucose tolerance (OGTT) test as well as glycohemoglobin (HbA1c). Nevertheless, perfluorohexane sulfonic acid (PFHxS), 4:2 fluorotelomer sulfonates (FTSs), and 3H-perfluoro-3-[(3-methoxy-propoxy) propanoic acid] (ADONA) exhibited protective effects on some of these glycemic outcomes. When assessing the PFASs as mixtures by conducting the Bayesian kernel machine regression (BKMR), the risks of GDM and values of glycemic outcomes increased significantly as the concentrations of the PFASs mixture increased, with PFOA being the largest contributor. We therefore propose that although the effects on glucose homeostasis varied between different PFAS congeners, the elevated combined exposures to PFASs may be associated with substantially increased GDM risks by altering glucose metabolism.

A Theoretical Study of the Interactions between Persistent Organic Pollutants and Graphene Oxide

Persistent organic pollutants (POPs) have adverse effects on the human health and ecosystem functioning. Graphene oxide (GO) has been developed to remove trace levels of POPs from wastewater samples. However, many questions involved in these processes are still unresolved (e.g., the role of π-π interaction, the effect of GO on the degradation of POPs, and so on). Revealing the microscopic interactions between GO and POPs is of benefit to resolve these questions. In the present study, a quantum chemical calculation was used to calculate the molecular doping and adsorption energy between eight representative POPs and GO. The influences of GO on the thermodynamic parameters, such as the Gibbs free energy and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, were also reported. We found the molecular doping is dependent on the species of POPs. The adsorption energy of the majority of POPs on GO is between 7 and 8 kJ/mol. Consequently, the GO may make degradation of POPs in wastewater more productive and lead to a change of kinetics of the degradation of POPs.

Exposure to perfluorooctane sulfonate in vitro perturbs the quality of porcine oocytes via induction of apoptosis

Perfluorooctane sulfonate (PFOS) is a widely used artificial surfactant with potential toxicity to humans and animals. However, little is known about the impact of PFOS on the female germ cell development. Here, we report that PFOS exposure weakens oocyte quality by disturbing oocyte meiotic competency and fertilization ability. Specifically, PFOS exposure impaired cytoskeleton assembly including spindle organization and actin polymerization to cause the oocyte maturation arrest. In addition, PFOS exposure also impaired the mitochondrial dynamics and function, resulting in the increased levels of reactive oxygen species (ROS) and DNA damage as well as generation of apoptosis. Lastly, PFOS exposure compromised the distribution of cortical granules (CGs) and their component ovastacin, leading to the failure of sperm binding and fertilization. Altogether, our study illustrates that oxidative stress-induced apoptosis is a major cause for the deteriorated quality of porcine oocytes exposed to PFOS.

A novel analytical strategy for the determination of perfluoroalkyl acids in various food matrices using a home-made functionalized fluorine interaction SPME in combination with LC-MS/MS

In this study, a fluorine-fluorine interaction approach through fluoridating boron nitride nanosheets (BNNs) for sensing perfluoroalkyl acids (PFAAs) in multiple food matrices was developed. Through a facile hydrothermal fluorination modification, the BNNs were transferred into homogeneous fluorinated boron nitride nanoparticles (F-BNNs) with robust networks and specific surface area. After morphological modification, the particles displayed strong adsorption and sensing capabilities on PFAAs in both solid and liquid food matrix. Under the evaluation of mass spectrometry, F-BNNs based microextraction approach exhibited low method detection limits (MDLs) in the ranges of 0.9-3.9 pg mL^-1 and 3.6-15.8 pg g^-1 for milk and meat matrices, respectively, with satisfactory repeatability (RSD% <13.5%) and recoveries (77.7-110.5%). This work not only depicted a facile approach for preparing F-BNNs based SPME fiber, but also provided a routine analysis protocol for monitoring PFAAs in food systems.

Challenges for Safe and Healthy Drinking Water in China

PURPOSE OF REVIEW

Rapid economic growth and its huge population are putting tremendous pressure on water sustainability in China. Ensuring clean drinking water is a great challenge for public health due to water shortage and pollution. This article reviews current scientific findings on health-related issues on drinking water and discusses the challenges for safe and healthy drinking water in China.

RECENT FINDINGS

From literature published since 2010, a variety of emerging contaminants were detected in drinking water, including disinfection byproducts (DBPs), pharmaceuticals and personal care products (PPCPs), endocrine-disrupting compounds (EDCs), antibiotic resistance genes, and pathogens. Arsenic and fluoride are still the two major contaminants in groundwater. Microcystins, toxins produced by cyanobacteria, were also frequently detected in surface water for drinking. Health effects of exposure to arsenic, fluoride, nitrates, DBPs, and noroviruses in drinking water have been reported in several epidemiological studies. According to literature, water scarcity is still a severe ongoing issue, and regional disparity affects the access to safe and healthy drinking water. In addition, urbanization and climate change have strong influences on drinking water quality and water quantity. Multiple classes of contaminants of emerging concern have been detected in drinking water, while epidemiological studies on their health effects are still inadequate. Water scarcity, regional disparity, urbanization, and climate change are the major challenges for safe and healthy drinking water in China.

The association between total serum isomers of per- and polyfluoroalkyl substances, lipid profiles, and the DNA oxidative/nitrative stress biomarkers in middle-aged Taiwanese adults

Per- and polyfluoroalkyl substances (PFAS) have been widely used in consumer products. In vitro and animal studies have demonstrated that exposure to perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonate (PFOS) increases oxidative/nitrative stress. Recent studies have also found that isomers of PFOA/PFOS may have unique biological effects on clinical parameters. However, the correlation between PFOA/PFOS isomers and markers of oxidative/nitrative stress has never been investigated in the general population. In the current study, 597 adult subjects (ages between 22 and 63 years old) were enrolled from a control group of a case-control study entitled "Work-related risk factors and coronary heart disease". We investigated the correlation between the serum isomers of PFOA/PFOS, lipid profiles, and the urine compounds 8-hydroxy-2-deoxyguanosine (8-OHdG) and 8-nitroguanine (8-NO2Gua) in these participants. There were 519 men and 78 women with a mean age of 45.8 years. Linear PFOA levels were positively correlated with serum low density lipoprotein cholesterol (LDL-C), small dense LDL, and triglyceride, and linear PFOS levels were positively correlated with LDL-C and HDL-C in multiple linear regression analyses. After controlling for potential confounders, the mean levels of 8-OHdG and 8-NO2Gua significantly increased across the quartiles of linear PFOS in multiple linear regression analyses. When both the 8-OHdG and 8-NO2Gua levels were above the 50th percentile, the odds ratio (OR) of higher levels of LDL-C (>75th percentile) with one unit increase in ln linear PFOS level was the highest (OR 3.15 (95% CI = 1.45-6.64), P = 0.003) in logistic regression models. In conclusion, serum linear PFOA/PFOS were correlated with lipid profiles, and linear PFOS was associated with urine oxidative/nitrative stress biomarkers. The positive correlation between linear PFOS and LDL-C was more marked when concentrations of urine oxidative/nitrative stress biomarkers were elevated. Further studies are needed to elucidate the causal relationships among PFAS isomers, lipid profiles, and oxidative/nitrative stress.

Isomers of per- and polyfluoroalkyl substances and uric acid in adults: Isomers of C8 Health Project in China

BACKGROUND

Greater levels of serum per- and polyfluoroalkyl substances (PFAS) are known to be associated with higher uric acid which itself leads to a number of chronic diseases. However, whether this association varies across PFAS isomers which recently have been found to be associated with human health remains unknown.

OBJECTIVES

To address this research gap, we explored isomer-specific associations between serum PFAS and uric acid in Chinese adults.

METHODS

We conducted a cross-sectional study of associations between serum PFAS isomer and serum uric acid in 1612 participants from the Isomer of C8 Health Project. We used multivariable linear and logistic regression models to analyze serum isomers of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and other PFASs as continuous and categorical predictors of uric acid, adjusted for confounders. The association was also stratified by kidney function stage based on estimated glomerular filtration rate (GF-1, GF-2, GF-3a, and GF-3b/4).

RESULTS

We found positive associations between serum PFAS isomer concentrations and uric acid. Uric acid levels were greater for each log-unit increase in branched PFOA (β = 0.30, 95% CI: 0.21, 0.40), linear PFOA (β = 0.18, 95% CI: 0.09, 0.26), branched PFOS (β = 0.09, 95% CI: 0.02, 0.17) and linear PFOS (β = 0.06, 95% CI: -0.01, 0.14) concentration. The associations between PFAS and uric acid showed an inverted 'U' shaped pattern across kidney function stages. For example, uric acid level was greater with each log-unit increase in total-PFOA among GF-1 (β = 0.21, 95% CI: 0.06, 0.37), this relationship was greater in GF-3a (β = 0.49, 95% CI: 0.09, 0.89) and decreased in GF-3b/4 (β = -0.22, 95% CI: -0.83, 0.39). We also found the odds of hyperuricemia increased linearly with increasing branched PFOA in quartiles (odds ratio = 2.67, 95% CI: 1.86, 3.85 at the highest quartile).

CONCLUSION

We report novel results in which PFAS associations with uric acid varied according to isomer and adult kidney function. Besides, our findings are consistent with previous epidemiologic studies in finding a positive association between serum PFAS concentrations and serum uric acid, especially for PFOA. Our results indicate that more research is needed to more clearly assess the impact of PFAS isomers on human health, which will help to refine regulation policies for PFAS.

Sorption of PFOS isomers on goethite as a function of pH, dissolved organic matter (humic and fulvic acid) and sulfate

Understanding the distribution of PFOS isomers between the aqueous phase and goethite is crucial, since it is an abundant sorbent and thus may have a large influence on the mobility of PFOS. This study was conducted to understand the effects of pH, humic acid (HA), fulvic acid (FA) and sulfate on sorption of PFOS isomers. The results will increase the understanding about what parameters may control the fate and transport of PFOS in surface and ground water. The study was conducted by adding PFOS spiked water to a goethite slurry with different aqueous chemistry. Levels of total PFOS and PFOS isomers were quantified using an Ultra-Performance Liquid Chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that sorption of PFOS was mainly dependent on pH; sorption decreased as pH increased. Presence of HA increased log K_d from 1.29 to 2.03, 1.76 to 1.92 and 1.51 to 1.96 at pH 5.50-7.50 for 3-/4-/4-PFOS, 6-/2-PFOS and L-PFOS, respectively. Changes in the aqueous chemistry also affected the behaviour of PFOS as the addition of Na₂SO₄ enhanced the sorption of PFOS. Results showed that L-PFOS was more readily sorbed to goethite at pH < 4.35 both in the presence and in the absence of humic or fulvic acids. At pH > 4.5 the 3-/4-/5-PFOS isomer group was more associated to goethite. Besides electrostatic interactions, which controlled the sorption of PFOS, this study indicate that the presence of dissolved humic substances in the aqueous phase enhances the sorption via hydrophobic mechanisms.

Levels, spatial distribution and isomer profiles of perfluoroalkyl acids in soil, groundwater and tap water around a manufactory in China

In this study, 32 surface soil samples, 24 groundwater samples, and 6 tap water samples were collected around a perfluorosulfonates (PFSAs) manufactory in China to analyze the distributions of perfluoroalkyl acids (PFAAs) including linear and branched isomers. The total concentrations of PFAAs (∑PFAAs) ranged from 1.30 to 913 ng/g on a dry weight basis (dw), 31.4-15656 ng/L, and 11.8-59.7 ng/L in soil, groundwater and tap water samples respectively. Perfluorooctanesulfonate (PFOS) and perfluorobutanoic acid (PFBA) were the predominant PFAAs in the soil whereas PFBA was the predominant congener in groundwater. PFAA concentrations in the soil and groundwater decreased with increasing distance from the manufactory. Shorter-chain PFAAs showed higher proportions in groundwater than in soil samples and that shorter-chain PFAAs exhibited faster decreasing rates in soil samples, which may be due to the differences in the polarity and hydrophobicity of these molecules. For isomer profiles, n-PFHxS, n-PFOS, and n-PFOA were the main isomer in soil samples and groundwater samples. Direct exposure to PFOS and PFOA via the soil and tap water posed relatively low risk to the residents' health.

Tap Water Contributions to Plasma Concentrations of Poly- and Perfluoroalkyl Substances (PFAS) in a Nationwide Prospective Cohort of U.S. Women

BACKGROUND

Between 2013 and 2015, concentrations of poly- and perfluoroalkyl substances (PFAS) in public drinking water supplies serving at least six million individuals exceeded the level set forth in the health advisory established by the U.S. Environmental Protection Agency. Other than data reported for contaminated sites, no systematic or prospective data exist on the relative source contribution (RSC) of drinking water to human PFAS exposures.

OBJECTIVES

This study estimates the RSC of tap water to overall PFAS exposure among members of the general U.S.

POPULATION

METHODS

We measured concentrations of 15 PFAS in home tap water samples collected in 1989-1990 from 225 participants in a nationwide prospective cohort of U.S. women: the Nurses' Health Study (NHS). We used a one-compartment toxicokinetic model to estimate plasma concentrations corresponding to tap water intake of PFAS. We compared modeled results with measured plasma PFAS concentrations among a subset of 110 NHS participants.

RESULTS

Tap water perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) were statistically significant predictors of plasma concentrations among individuals who consumed [Formula: see text] cups of tap water per day. Modeled median contributions of tap water to measured plasma concentrations were: PFOA 12% (95% probability interval 11%-14%), PFNA 13% (8.7%-21%), linear perfluorooctanesulfonic acid (nPFOS) 2.2% (2.0%-2.5%), branched perfluorooctanesulfonic acid (brPFOS) 3.0% (2.5%-3.2%), and perfluorohexanesulfonic acid (PFHxS) 34% (29%-39%). In five locations, comparisons of PFASs in community tap water collected in the period 2013-2016 with samples from 1989-1990 indicated increases in quantifiable PFAS and extractable organic fluorine (a proxy for unquantified PFAS).

CONCLUSIONS

Our results for 1989-1990 compare well with the default RSC of 20% used in risk assessments for legacy PFAS by many agencies. Future evaluation of drinking water exposures should incorporate emerging PFAS. https://doi.org/10.1289/EHP4093.

Liver function biomarkers disorder is associated with exposure to perfluoroalkyl acids in adults: Isomers of C8 Health Project in China

Exposure to chemicals may affect liver enzyme to increase the risk of liver diseases. Perfluoroalkyl acids (PFAAs) are one kind of persistent organic pollutants with hepatotoxic effect in organism. However, data is scarce to characterize the hepatotoxic effects of specific structural PFAA isomers in general population. To address this data gap, we evaluated the association between serum PFAAs concentration and liver function biomarkers in the Isomers of C8 Health Project in China. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to measure 18 serum PFAAs, except for linear and branched isomers of PFOA/PFOS, nine perfluorinated carboxylic acids (PFCAs) and two perfluorinated sulfonic acids (PFSAs) were also included, in 1605 adult residents of Shenyang, China. Values for nine serum liver function biomarkers were determined by full-automatic blood biochemical analyzer. Linear regression was used to evaluate associations between PFAAs and continuous liver function biomarkers and logistic regression to assess markers dichotomized per clinical reference intervals. Results indicated that serum PFAAs concentrations were associated with liver biomarker levels suggestive of hepatotoxicity, especially for liver cell injury. For example, a 1 ln-unit increase in total- perfluorooctanoic acid (PFOA) exposure was associated with a 7.4% [95% confidence interval (CI): 3.9%, 11.0%] higher alanine aminotransferase (ALT) level in serum. Interestingly, we observed association between branched PFAA isomers and liver biomarkers. For example, one ln-unit increase in branched perfluorooctane sulfonate (PFOS) isomers exposure was associated with a 4.3% increase in ALT level (95% CI: 1.2%, 7.4%) and a 33.0% increased odds of having abnormal ALT (95% CI: 5.0%, 67.0%). Also, we found that PFNA had positive association with ALT [(6.2%, 95% CI: 3.1%, 9.4%) and AST levels (2.5%, 95% CI: 0.5%, 4.5%)]. Logistic regression results showed that PFPeA, PFHxA, PFNA, PFDoDA, PFTrDA and PFTeDA had statistically association with abnormal prealbumin. Conclusively, our results support previous studies showing association between PFAAs exposure and liver function biomarkers. We found new evidence that branched PFAAs isomer exposure is associated with the risk of clinically relevant hepatocellular dysfunction.

Renal function and isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS): Isomers of C8 Health Project in China

Perfluoroalkyl substances (PFASs) are widely-utilized synthetic chemicals commonly found in industrial and consumer products. Previous studies have examined associations between PFASs and renal function, yet the results are mixed. Moreover, evidence on the associations of isomers of PFASs with renal function in population from high polluted areas is scant. To help to address this data gap, we used high performance liquid chromatography-mass spectrometry to measure serum isomers of perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), and other PFASs from 1612 adults residing in Shenyang, China, and characterized their associations with estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD). Results showed that after adjusted for multiple confounding factors, most of the higher fluorinated PFASs, except for PFOA and PFDA, were negatively associated with eGFR and positively associated with CKD. Compared with linear PFOS (n-PFOS), branched PFOS isomers (Br-PFOS) were more strongly associated with eGFR (Br-PFOS; β = -1.22, 95%CI: 2.02, -0.42; p = 0.003 vs. n-PFOS; β = -0.16, 95%CI: 0.98, 0.65; p = 0.691) and CKD (Br-PFOS; OR = 1.27; 95% CI: 1.02, 1.58; p = 0.037 vs. n-PFOS; OR = 0.98; 95% CI: 0.80, 1.20; p = 0.834). In conclusion, branched PFOS isomers were negatively associated with renal function whereas their linear counterparts were not. Given widespread exposure to PFASs, potential nephrotoxic effects are of great public health concern, Furthermore, longitudinal research on the potential nephrotoxic effects of PFASs isomers will be necessary to more definitively assess the risk.

Simultaneous determination of (N-ethyl perfluorooctanesulfonamido ethanol)-based phosphate diester and triester and their biotransformation to perfluorooctanesulfonate in freshwater sediments

While (N-ethyl perfluorooctanesulfonamido ethanol)-based phosphates (SAmPAPs) have been proposed as a group of perfluorooctanesulfonate (PFOS) precursors, investigation of their occurrence and fate has been limited to SAmPAP diester. In this study, SAmPAP diester and triester were simultaneously determined in freshwater sediment from Taihu Lake using a newly developed UPLC-MS/MS method, and their biotransformation to PFOS in lake sediment was investigated. SAmPAP diester and triester were detected in sediments with a detection frequency of 56% and 88%, and their mean concentrations were 0.24 ± 0.11 ng/g dry weight (dw) and 0.12 ± 0.03 ng/g dw, respectively. The SAmPAP diester/triester ratio in sediment was 1.1 ± 4.2, much lower than that (6.7) observed in the technical product, and the positive correlation was found between the concentrations of SAmPAP diester and PFOS in sediments (r² = 0.45, p = 0.01), suggesting that SAmPAP diester would be biotransformed to PFOS in the lake sediment. The microbial degradation test in the lake sediments further clarified that SAmPAP diester was biodegraded to PFOS, but SAmPAP triester was highly recalcitrant to microbial degradation. This study suggests that the occurrence of SAmPAP diester in freshwater lake sediments may be an important precursor of PFOS.

Early life exposure to per- and polyfluoroalkyl substances and mid-childhood lipid and alanine aminotransferase levels

BACKGROUND

Growing evidence suggests that exposure to per- and polyfluoroalkyl substances (PFASs) may disrupt lipid homeostasis and liver function, but data in children are limited.

OBJECTIVE

We examined the association of prenatal and mid-childhood PFAS exposure with lipids and alanine aminotransferase (ALT) levels in children.

METHODS

We studied 682 mother-child pairs from a Boston-area pre-birth cohort. We quantified PFASs in maternal plasma collected in pregnancy (median 9.7weeks gestation, 1999-2002) and in child plasma collected in mid-childhood (median age 7.7years, 2007-2010). In mid-childhood we also measured fasting total (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and ALT. We then derived low-density lipoprotein cholesterol (LDL-C) from TC, HDL-C, and TG using the Friedewald formula.

RESULTS

Median (interquartile range, IQR) perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorodecanoate (PFDeA) concentrations in child plasma were 6.2 (5.5), 4.3 (3.0), and 0.3 (0.3) ng/mL, respectively. Among girls, higher child PFOS, PFOA, and PFDeA concentrations were associated with detrimental changes in the lipid profile, including higher TC and/or LDL-C [e.g., β per IQR increment in PFOS=4.0mg/dL (95% CI: 0.3, 7.8) for TC and 2.6mg/dL (-0.5, 5.8) for LDL-C]. However, among both boys and girls, higher plasma concentrations of these child PFASs were also associated with higher HDL-C, which predicts better cardiovascular health, and slightly lower ALT, which may indicate better liver function. Prenatal PFAS concentrations were also modestly associated with improved childhood lipid and ALT levels.

CONCLUSIONS

Our data suggest that prenatal and mid-childhood PFAS exposure may be associated with modest, but somewhat conflicting changes in the lipid profile and ALT levels in children.

Improving nutrient removal performance of surface flow constructed wetlands in winter using hardy submerged plant-benthic fauna systems

A novel hardy submerged plant-benthic fauna systems to enhance the performance of surface flow constructed wetlands in winter.

Association among total serum isomers of perfluorinated chemicals, glucose homeostasis, lipid profiles, serum protein and metabolic syndrome in adults: NHANES, 2013-2014

Perfluorinated chemicals (PFCs) have been used widely in consumer products manufacture. Recent in vitro as well as animal studies have found that there are different toxicity and pharmacokinetic profiles between isomers of perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonate (PFOS). However, the differential effects of linear or branched PFOA/PFOS isomers on human beings have never been reported. Herein, we examined 1871 adult subjects (age older than 18 years) from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 to determine the association between the isomers of PFOA/PFOS and serum biochemistry profiles, including glucose, lipids, protein and components of metabolic syndrome (MS). The results showed that for PFOA, increased linear PFOA was associated with increases in total cholesterol, serum albumin and an enhancement of β cell function as well as a decrease in the serum globulin. Increased branched PFOA was significantly associated with increased fasting glucose. All isomers of PFOA were positively associated with high-density lipoprotein-cholesterol (HDL-C) and negatively associated with glycohemoglobin (HbA1C). The branched PFOS was positively associated with β cell function and inversely associated with serum globulin. Both linear and branched isomers of PFOS were positively associated with the total protein and albumin. The increased branched PFOA was associated with less HDL-C insufficiency defined by the National Cholesterol Education Program Third Adult Treatment Panel (NCEP-ATP III) MS criteria, whereas the increased concentrations of serum total and linear PFOS were associated with less hypertriglyceridemia by the NCEP-ATP III. In conclusion, serum isomers of PFOA and PFOS were associated with glucose homeostasis, serum protein as well as lipid profiles; they were also indicators of MS. This may suggest that there is a distinct difference in the toxicokinetics of the isomers of PFOA and PFOS. Further clinical and animal studies are warranted to clarify the putative causal relationships between isomers and biochemical alterations.

A new method to quantify the health risks from sources of perfluoroalkyl substances, combined with positive matrix factorization and risk assessment models

A hybrid model based on the positive matrix factorization (PMF) model and the health risk assessment model for assessing risks associated with sources of perfluoroalkyl substances (PFASs) in water was established and applied at Dianchi Lake to test its applicability. The new method contains 2 stages: 1) the sources of PFASs were apportioned by the PMF model and 2) the contribution of health risks from each source was calculated by the new hybrid model. Two factors were extracted by PMF, with factor 1 identified as aqueous fire-fighting foams source and factor 2 as fluoropolymer manufacturing and processing and perfluorooctanoic acid production source. The health risk of PFASs in the water assessed by the health risk assessment model was 9.54 × 10^-7  a^-1 on average, showing no obvious adverse effects to human health. The 2 sources' risks estimated by the new hybrid model ranged from 2.95 × 10^-10 to 6.60 × 10^-6  a^-1 and from 1.64 × 10^-7 to 1.62 × 10^-6  a^-1 , respectively. The new hybrid model can provide useful information on the health risks of PFAS sources, which is helpful for pollution control and environmental management. Environ Toxicol Chem 2018;37:107-115. © 2017 SETAC.

Early-Life Exposure to Perfluoroalkyl Substances and Childhood Metabolic Function

BACKGROUND

Perfluoroalkyl substances (PFASs) are synthetic chemicals that may persist in the environment and in humans. There is a possible association between early-life PFAS exposure and metabolic dysfunction in later life, but data are limited.

METHODS

We studied 665 mother-child pairs in Project Viva, a Boston, Massachusetts-area cohort recruited 1999-2002. We quantified concentrations of PFASs [perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorodecanoate (PFDeA)] in maternal plasma collected at the first prenatal visit (median, 9.6 weeks gestation) and in child plasma from the mid-childhood research visit (median, 7.7 years). We assessed leptin, adiponectin, and homeostatic model assessment of insulin resistance (HOMA-IR) in mid-childhood. We fit covariate-adjusted linear regression models and conducted stratified analyses by child sex.

RESULTS

Children with higher PFAS concentrations had lower HOMA-IR [e.g., -10.1% (95% CI: -17.3, -2.3) per interquartile range increment in PFOA]. This inverse association between child PFAS and HOMA-IR was more pronounced in females [e.g., PFOA: -15.6% (95% CI: -25.4, -4.6) vs. -6.1% (95% CI: -16.2, 5.2) for males]. Child PFAS plasma concentrations were not associated with leptin or adiponectin. Prenatal PFAS plasma concentrations were not associated with leptin, adiponectin, or HOMA-IR in offspring.

CONCLUSIONS

We found no evidence for an adverse effect of early-life PFAS exposure on metabolic function in mid-childhood. In fact, children with higher PFAS concentrations had lower insulin resistance. Citation: Fleisch AF, Rifas-Shiman SL, Mora AM, Calafat AM, Ye X, Luttmann-Gibson H, Gillman MW, Oken E, Sagiv SK. 2017. Early-life exposure to perfluoroalkyl substances and childhood metabolic function. Environ Health Perspect 125:481-487; http://dx.doi.org/10.1289/EHP303.

Impacts of daily intakes on the isomeric profiles of perfluoroalkyl substances (PFASs) in human serum

Perfluoroalkyl substances (PFASs) have been well studied in human daily intake for assessment of potential health risks. However, little is known about the isomeric compositions of PFASs in daily intake and their impacts on isomeric profiles in humans. In this study, we investigated the occurrence of PFASs with isomeric analysis in various human exposure matrices including foodstuffs, tap water and indoor dust. Perfluorooctanesulfonate (PFOS) and/or perfluorooctanoate (PFOA) were predominant in these exposure matrices collected in Tianjin, China. In fish and meat, linear (n-) PFOA was enriched with a percentage of 92.2% and 99.6%, respectively. Although n-PFOS was higher in fish (84.8%) than in technical PFOS (ca. 70%), it was much lower in meat (63.1%) and vegetables (58.5%). Dietary intake contributed >99% of the estimated daily intake (EDI) for the general population. The isomeric profiles of PFOA and PFOS in human serum were predicted based on the EDI and a one-compartment, first-order pharmacokinetic model. The isomeric percentage of n-PFOA in the EDI (98.6%) was similar to that in human serum (predicted: 98.2%, previously measured: 99.7%) of Tianjin residents. The results suggest direct PFOA intake plays an important role in its isomeric compositions in humans. For PFOS, the predicted n-PFOS (69.3%) was much higher than the previously measured values (59.2%) in human serum. This implies that other factors, such as indirect exposure to PFOS precursors and multiple excretion pathways, may contribute to the lower percentage of n-PFOS in humans than of technical PFOS.