Relationship between perfluorooctanoate and perfluorooctane sulfonate blood concentrations in the general population and routine drinking water exposure

Estimation of internal human daily intakes of organophosphate esters using one-compartment toxicokinetic model in the whole blood from Hebei Province, China

To evaluate the human health risks attributed by organophosphate ester (OPE) exposure, it is very important to estimate the daily intakes (DIs) of OPEs in human. In this study, the DIs of OPEs were estimated using a simplified one-compartment toxicokinetic model based on their total clearance rates in human and their whole blood concentrations. Thirty paired human whole blood and plasma samples were collected from participants in Hengshui, Hebei Province, China. The detection frequencies of most OPEs in the whole blood were lower than 50.0%. Thus, the OPE levels in whole blood were converted from the corresponding plasma levels using the fractions of OPEs in plasma (F_p), which were estimated from an in vitro partition assay and the values were in the range of 0.52-0.98. The measured whole blood concentrations of triphenyl phosphate (TPHP) and tris(chloroethyl) phosphate (TCEP) were comparable to those converted from the plasma concentrations, suggesting that the conversion method was reliable. The estimated total DIs of TPHP, TCEP, and tris(2-chloroisopropyl) phosphate were 1-30 times of those derived by the external exposure method, which usually excluded many exposure sources. The estimated human health risks based on the DIs indicated that the carcinogenic and non-carcinogenic effects of OPEs for the participants in Hengshui, Hebei Province, China, were negligible. This study recommended a more reliable and simpler method to estimate the human health risks attributed to the exposure of OPEs.

Serum Half-Lives for Short- and Long-Chain Perfluoroalkyl Acids after Ceasing Exposure from Drinking Water Contaminated by Firefighting Foam

BACKGROUND

Firefighting foam-contaminated ground water, which contains high levels of perfluoroalkyl substances (PFAS), is frequently found around airports. In 2018 it was detected that employees at a municipal airport in northern Sweden had been exposed to high levels of short-chain PFAS along with legacy PFAS (i.e., PFOA, PFHxS, and PFOS) through drinking water.

OBJECTIVES

In this study, we aimed to describe the PFAS profile in drinking water and biological samples (paired serum and urine) and to estimate serum half-lives of the short-chain PFAS together with legacy PFAS.

METHODS

Within 2 weeks after provision of clean water, blood sampling was performed in all 26 airport employees. Seventeen of them were then followed up monthly for 5 months. PFHxA, PFHpA, PFBS, PFPeS, and PFHpS together with legacy PFAS in water and biological samples were quantified using LC/MS/MS. Half-lives were estimated by assuming one compartment, first-order elimination kinetics.

RESULTS

The proportions of PFHxA, PFHpA, and PFBS were higher in drinking water than in serum. The opposite was found for PFHxS and PFOS. The legacy PFAS accounted for about 50% of total PFAS in drinking water and 90% in serum. Urinary PFAS levels were very low compared with serum. PFBS showed the shortest half-life {average 44 d [95% confidence interval (CI): 37, 55 d]}, followed by PFHpA [62 d (95% CI: 51, 80 d)]. PFPeS and PFHpS showed average half-lives as 0.63 and 1.46 y, respectively. Branched PFOS isomers had average half-lives ranging from 1.05 to 1.26 y for different isomers. PFOA, PFHxS, and linear PFOS isomers showed average half-lives of 1.77, 2.87, and 2.93 y, respectively.

DISCUSSION

A general pattern of increasing half-lives with increasing chain length was observed. Branched PFOS isomers had shorter half-lives than linear PFOS isomers. https://doi.org/10.1289/EHP6785.

Nontargeted identification of per- and polyfluoroalkyl substances in human follicular fluid and their blood-follicle transfer

The female reproductive toxicity of per- and polyfluoroalkyl substances (PFAS) has raised concerns, but knowledge about their human preconception exposure is limited. In this study, 15 emerging PFAS were identified in follicular fluid samples from healthy women by using high-resolution mass spectrometry, and Cl-substituted perfluoroalkyl ether sulfonates (Cl-PFESAs) including 4:2, 5:2, 6:2, and 8:2 Cl-PFESAs, 4:4 C₈ perfluoroalkyl ether sulfonate (PFESA), C₈ perfluoroalkyl ether carboxylate (PFECA), and C₈ polyether PFECA (Po-PFECA) were detected in over 50% of 28 follicular fluid samples. Ten legacy PFAS were also detected, and the geometric mean concentration of PFOS was the highest (4.82 ng/mL), followed by PFOA (4.60 ng/mL), 6:2 Cl-PFESA (1.09 ng/mL), PFHxS (0.515 ng/mL), PFNA (0.498 ng/mL), and C₈ PFECA (0.367 ng/mL). The blood-follicle transfer efficiencies for PFCAs decreased with increasing chain length (0.96 for PFHpA, 0.56 for PFTriDA), and the transfer efficiencies of C₈ PFECA (0.78) was significantly higher than that of PFOA (0.76). The transfer efficiencies of 4:2 Cl-PFESA (0.73), 6:2 Cl-PFESA (0.75) and 8:2 Cl-PFESA (0.91) were significantly higher than that (0.70) of PFOS (p = 0.028, 0.026 and 0.002, respectively). This study constitutes the first report of the human oocyte exposure to emerging PFAS and their blood-follicle transfer abilities.

Efficient detection and assessment of human exposure to trace antibiotic residues in drinking water

Human exposure to antibiotic residues in drinking water has not been well evaluated. This study is the first attempt to simultaneously and efficiently identify and quantify 92 antibiotic residues in filtered tap water (multistage filtration at the tap) (n = 36) collected from 10 areas of a large city in southern China, 10 Chinese brands of bottled/barreled water (n = 30) and six foreign brands of bottled water (n = 18) obtained from the Chinese market. The average and median concentrations of all the detected antibiotic compounds was 182 and 92 ng/L in filtered tap water, 180 and 105 ng/L in Chinese brands of bottled/barreled water, and 666 and 146 ng/L in foreign brands of bottled water, respectively. A total of 58 antibiotics were detected in the filtered tap water, and 45 and 36 antibiotics were detected in the Chinese and foreign brands of bottled water, respectively. More types of antibiotics were detected in Chinese brands of bottled water than in the other bottled waters. In addition, Chinese waters had high roxithromycin concentrations, while the foreign brands of bottled water had high concentrations of dicloxacillin. The average and median values of the estimated overall daily intake of all the detected antibiotics were 4.3 and 2.3 ng/kg/day when only filtered tap water was drunk, 4.0 and 2.5 ng/kg/day when Chinese brands of bottled water was drunk, and 16.0 and 4.9 ng/kg/day when foreign brands of bottled water was drunk. Further study is needed to develop a more comprehensive estimation of human exposure to antibiotic residues in the environment and a more in-depth understanding of the potential hazard of ingested antibiotic residues to the human microbiome.

Perfluoroalkyl Substances in Drinking Water, Indoor Air and Dust from Ireland: Implications for Human Exposure

Perfluoroalkyl substances (PFASs) were measured in air and dust from cars, homes, offices, and school classrooms in Ireland, along with drinking water from homes and offices. Perfluorooctanoic acid (PFOA) dominated air and drinking water, while perfluorobutane sulfonate (PFBS) dominated dust. This is the first report of PFOA, perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), PFBS, and perfluorononanoic acid (PFNA) in air inside cars and school classrooms. PFOS concentrations in classroom air exceeded significantly (p ≤ 0.05) those in homes. Atmospheric concentrations of PFOA, PFNA, and methyl perfluorooctane sulfonamido ethanol (MeFOSE) (p ≤ 0.05) were significantly higher in cars containing child car seats than in cars without. PFOS, PFOA, PFBS, and PFHxS were all detected frequently in drinking water, but concentrations of PFASs were low, and although ΣPFASs were 64 ng/L in one bottled water sample, this fell below a Swedish Action Level of 90 ng ΣPFASs/L. The Irish population's exposure to PFOS and PFOA via non-dietary sources is well below estimates of dietary exposure elsewhere in Europe. Moreover, even under a high-end exposure scenario, it falls below the European Food Safety Authority's (EFSA) provisional tolerable weekly intakes for PFOS and PFOA.

Contamination Profiles of Perfluoroalkyl Substances (PFAS) in Groundwater in the Alluvial-Pluvial Plain of Hutuo River, China

Over the past decade, concerns about perfluoroalkyl substances (PFAS) have increased rapidly among the scientific community due to their global distribution and persistence in various environmental matrices. The occurrences of 10 PFAS in groundwater in the alluvial-pluvial plain of Hutuo River (APPHR) in the North China Plain (NCP) were analyzed via UPLC-MS/MS and solid phase extraction. Total PFAS concentrations ranged from 0.56 ng/L to 13.34 ng/L, with an average value of 2.35 ng/L. Perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) were dominant PFAS contaminants with high detection rates of 98.39% and 95.16%, respectively, and PFOA was the main pollutant with a mean concentration of 0.65 ng/L. The hydrogeological conditions have an important influence on the concentrations of PFAS in groundwater. Comparatively, the concentration of PFAS in groundwater in the study area is not very high, but it reflects that the groundwater in this region is affected by industrial sources to some extent. Local government should pay more attention on industrial pollution control and groundwater protection in this area.

Human exposure to per- and polyfluoroalkyl substances (PFAS) through drinking water: A review of the recent scientific literature

Per- and polyfluoroalkyl substances (PFAS) are a group of water-soluble chemical compounds with an important number of applications, which have been widely used during the last 60 years. Two of them, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are the most known and well investigated. As for many other organic substances that are of environmental concern, the diet is the main route of human exposure to PFAS. However, in certain cases drinking water may also mean a significant contribution to human exposure, and to a lesser extent, dust and air (indoor exposure). In recent years, the environmental persistence of PFAS, their biomagnification in food webs, as well as their potential accumulation and toxicity, have generated a notable interest, which has been evidenced by the considerable number of publications in this regard. Recently, we carried out a wide revision on the levels of PFAS in food and human dietary intake. In the current review, we have summarized the recent information (last 10 years) published in the scientific literature (Scopus and PubMed) on the concentrations of PFAS in drinking water and the human health risks derived from the regular water consumption, when available. A large amount of data belongs to PFOS and PFOA and corresponds to studies mainly conducted in countries of the European Union, USA and China, although no information is available for most countries over the world. According to the toxicological information about PFAS that is so far available, the current health risks for the regular consumers of municipal/tap water do not seem to be of concern according to the levels considered as acceptable for various regulatory institutions.

Regulation of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) in Drinking Water: A Comprehensive Review

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are receiving global attention due to their persistence in the environment through wastewater effluent discharges and past improper industrial waste disposal. They are resistant to biological degradation and if present in wastewater are discharged into the environment. The US Environmental Protection Agency (USEPA) issued drinking water Health Advisories for PFOA and PFOS at 70 ng/L each and for the sum of the two. The need for an enforceable primary drinking water regulation under the Safe Drinking Water Act (SDWA) is currently being assessed. The USEPA faces stringent legal constraints and technical barriers to develop a primary drinking water regulation for PFOA and PFOS. This review synthesizes current knowledge providing a publicly available, comprehensive point of reference for researchers, water utilities, industry, and regulatory agencies to better understand and address cross-cutting issues associated with regulation of PFOA and PFOS contamination of drinking water.

Novel insights into the competitive adsorption behavior and mechanism of per- and polyfluoroalkyl substances on the anion-exchange resin

Per- and polyfluoroalkyl substances (PFASs) are widely used and co-exist in various aquatic environments, but their co-removal is not clear. In this study, the competitive adsorption behavior and mechanism of six traditional and emerging PFASs on anion-exchange resin IRA67 in the bisolute and mixed systems were studied. The adsorption equilibrium of the long-chain PFASs was at least 96 h whereas 48 h was required for the short-chain PFASs. When the PFASs were co-removed in the bisolute system, their competition was not obvious at low PFAS concentration of 0.01597 mmol/L due to the relatively adequate adsorption sites. When the concentrations of PFASs were increased to 0.07666 mmol/L, the removal of perfluorobutanoic acid (PFBA) and perfluorobutane sulfonate (PFBS) decreased by 77.78% and 72.09%, respectively. The competitive experiments showed that the adsorbed short-chain PFASs could be replaced by the long-chain ones, which was closely related to their hydrophobicity, backbone and functional groups. With the increase of solution pH from 3 to 7, the polyamine groups on the resin IRA67 were transferred to the base forms and the effective adsorption sites decreased, resulting in a more obvious competitive replacement behavior. This study suggested that the PFASs with long chain could be more effectively removed from the coexisting PFASs solution by the anion-exchange resins, and the short-chain PFASs in water may be removed when high dosage of anion-exchange resins is applied or the solution pH is decreased.

Toxicokinetics of perfluorobutane sulfonate (PFBS), perfluorohexane-1-sulphonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS) in male and female Hsd:Sprague Dawley SD rats after intravenous and gavage administration

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In rats, the half-life of perfluoroalkyl sulfonic acids decreased with shorter chain lengths.

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Sex differences in kinetics were found for PFBS and PFHxS but not PFOS.

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Perfluoroalkyl sulfonic acids were highly present in the liver but not the brain.

Perfluorinated alkyl substances (PFAS) are persistent contaminants that have been detected in the environment and in humans. With the PFAS chemical class, there are perfluorinated alkyl acids, many of which have been associated with certain toxicities. Because toxicity testing cannot feasibly be conducted for each individual PFAS, the National Toxicology Program (NTP) designed studies to compare toxicities across different subclasses of PFAS and across PFAS of different chain lengths to better understand the structure-toxicity relationship. Pharmacokinetic studies were conducted in parallel to these toxicity studies to facilitate comparisons across PFAS and to provide context for human relevance. Here, the toxicokinetic parameters of perfluorobutane sulfonate (PFBS), perfluorohexane-1-sulphonic acid (PFHxS), or perfluorooctane sulfonate (PFOS) after a single intravenous or gavage administration in male and female Hsd:Sprague-Dawley rats are reported. Concentrations of these PFAS were measured in the liver, kidney, and brain. Plasma half-life increased with longer chain length after gavage administration: PFBS- males averaged 3.3 h, females 1.3 h; PFHxS- males averaged 16.3 days, females 2.1 days; PFOS- males and females averaged ˜ 20 days. There were dose-dependent changes in clearance and systemic exposure for all administered chemicals and the direction of change was different in PFOS compared to the others. Liver:plasma ratios of PFOS were the highest followed by PFHxS and PFBS, while brain:plasma ratios were low in all three sulfonates. Sex differences in plasma half-life and tissue distribution were observed for PFBS and PFHxS, but not PFOS. These data provide a direct comparison of the kinetics of three different perfluoroalkyl sulfonic acids and allow for the contextualization of toxicity data in rats for human risk assessment of this chemical class.