Determinants of serum concentrations of perfluoroalkyl acids (PFAAs) in school children and the contribution of low-level PFAA-contaminated drinking water

Levels and spatial profile of per- and polyfluoroalkyl substances in edible shrimp products from Japan and neighboring countries; a potential source of dietary exposure to humans

Exposure to per- and polyfluoroalkyl substances (PFAS) is of great concern for human health because of their persistence and potentially adverse effects. Dietary intake, particularly through aquatic products, is a significant route of human exposure to PFAS. We analyzed perfluoroalkyl sulfonic acid (PFSA with carbon numbers from 6 to 8 and 10 (C６-C8, C10)) and perfluorooctanesulfonamide (FOSA), and perfluoroalkyl carboxylic acid (PFCA with carbon numbers from 6 to 15 (C6-C15)) in 30 retail packs of edible shrimps, which included seven species from eight coastal areas of Japan and neighboring countries. The most prevalent compounds were perfluorooctane sulfonate (PFOS, C8) and perfluoroundecanoic acid (PFUnDA, C11), accounting for 46 % of total PFAS. The concentrations ranged from 6.5 to 44 ng/g dry weight (dw) (equivalent to 1.5 to 10 ng/g wet weight (ww)) and varied according to species and location. For example, Alaskan pink shrimp (Pandalus eous) from the Hokuriku coast, Japan contained high levels of long-chain PFCAs (38 ng/g dw (equivalent to 8.7 ng/g ww)), while red rice prawn (Metapenaeopsis barbata) from Yamaguchi, Japan contained a high concentration of PFOS (29 ng/g dw (equivalent to 6.7 ng/g ww)). We also observed regional differences in the PFAS levels with higher concentrations of long-chain PFCAs in Japanese coastal waters than in the South China Sea. The PFAS profiles in shrimp were consistent with those in the diet and serum of Japanese consumers, suggesting that consumption of seafood such as shrimp may be an important source of exposure. The estimated daily intake of sum of all PFAS from shrimp from Japanese coastal water was 0.43 ng/kg body weight/day in average, which could reach the weekly tolerable values (4.4 ng/kg body weight /week) for the sum of the four PFSA set by the EFSA for heavy consumers. The high concentration of PFAS in shrimp warrants further investigation.

Per- and polyfluoroalkyl substances (PFAS) and fetal growth: A nation-wide register-based study on PFAS in drinking water

BACKGROUND

There is inconclusive evidence for an association between per- and polyfluoroalkyl substances (PFAS) and fetal growth.

OBJECTIVES

We conducted a nation-wide register-based cohort study to assess the associations of the estimated maternal exposure to the sum (PFAS4) of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) with birthweight as well as risk of small- (SGA) and large-for-gestational-age (LGA).

MATERIALS AND METHODS

We included all births in Sweden during 2012-2018 of mothers residing ≥ four years prior to partus in localities served by municipal drinking water where PFAS were measured in raw and drinking water. Using a one-compartment toxicokinetic model we estimated cumulative maternal blood levels of PFAS4 during pregnancy by linking residential history, municipal PFAS water concentration and year-specific background serum PFAS concentrations in Sweden. Individual birth outcomes and covariates were obtained via register linkage. Mean values and 95 % confidence intervals (CI) of β coefficients and odds ratios (OR) were estimated by linear and logistic regressions, respectively. Quantile g-computation regression was conducted to assess the impact of PFAS4 mixture.

RESULTS

Among the 248,804 singleton newborns included, no overall association was observed for PFAS4 and birthweight or SGA. However, an association was seen for LGA, multivariable-adjusted OR 1.08 (95% CI: 1.01-1.16) when comparing the highest PFAS4 quartile to the lowest. These associations remained for mixture effect approach where all PFAS, except for PFOA, contributed with a positive weight.

DISCUSSIONS

We observed an association of the sum of PFAS4 - especially PFOS - with increased risk of LGA, but not with SGA or birthweight. The limitations linked to the exposure assessment still require caution in the interpretation.

Socio-demographic inequalities influence differences in the chemical exposome among Swedish adolescents

Relatively little is known about the relationship between socio-demographic factors and the chemical exposome in adolescent populations. This knowledge gap hampers global efforts to meet certain UN sustainability goals. The present work addresses this problem in Swedish adolescents by discerning patterns within the chemical exposome and identify demographic groups susceptible to heightened exposures. Enlisting the Riksmaten Adolescents 2016-17 (RMA) study population (N = 1082) in human-biomonitoring, and using proportional odds ordinal logistic regression models, we examined the associations between concentrations of a diverse array of substances (N = 63) with the determinants: gender, age, participant/maternal birth country income per capita level, parental education levels, and geographic place of living (longitude/latitude). Participant/maternal birth country exhibited a significant association with the concentrations of 46 substances, followed by gender (N = 41), and longitude (N = 37). Notably, individuals born in high-income countries by high-income country mothers demonstrated substantially higher estimated adjusted means (EAM) concentrations of polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and per- and polyfluoroalkyl substances (PFASs) compared to those born in low-income countries by low-income country mothers. A reverse trend was observed for cobalt (Co), cadmium (Cd), lead (Pb), aluminium (Al), chlorinated pesticides, and phthalate metabolites. Males exhibited higher EAM concentrations of chromium (Cr), mercury (Hg), Pb, PCBs, chlorinated pesticides, BFRs and PFASs than females. In contrast, females displayed higher EAM concentrations of Mn, Co, Cd and metabolites of phthalates and phosphorous flame retardants, and phenolic substances. Geographical disparities, indicative of north-to-south or west-to-east substance concentrations gradients, were identified in Sweden. Only a limited number of lifestyle, physiological and dietary factors were identified as possible drivers of demographic inequalities for specific substances. This research underscores birth country, gender, and geographical disparities as contributors to exposure differences among Swedish adolescents. Identifying underlying drivers is crucial to addressing societal inequalities associated with chemical exposure and aligning with UN sustainability goals.

Determinants of PFOA Serum Half-Life after End of Exposure: A Longitudinal Study on Highly Exposed Subjects in the Veneto Region

BACKGROUND

Perfluoroalkyl substances (PFAS) are widely used, ubiquitous, and highly persistent man-made chemicals. Groundwater of a vast area of the Veneto Region (northeastern Italy) was found to be contaminated by PFAS from a manufacturing plant active since the late 1960s. As a result, residents were overexposed to PFAS through drinking water until 2013, mainly to perfluorooctanoic acid (PFOA).

OBJECTIVES

The aim of the present study was to estimate the rates of decline in serum PFOA and their corresponding serum half-lives, while characterizing their determinants.

METHODS

We investigated 5,860 subjects more than 14 years of age who enrolled in the second surveillance round of the regional health surveillance program. Two blood samples were collected between 2017 and 2022 (average time between measurements: 4 years). Serum PFOA excretion rates and half-lives were estimated based on linear mixed effect models, modeling subject-specific serum PFOA concentrations over time and correcting for background concentrations. For modeling determinants of half-life [age, sex, body mass index (BMI), smoking-habit, alcohol consumption, and estimated glomerular filtration rate (eGFR)], we added interaction terms between each covariate and the elapsed time between measurements. Perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) apparent half-lives were also estimated. A separate analysis was conducted in children (n = 480 ). All analyses were stratified by sex.

RESULTS

Median initial serum concentrations of PFOA was 49  ng / mL (range: 0.5-1,090), with a median reduction of 62.45%. The mean estimated PFOA half-life was 2.36 years [95% confidence interval (CI): 2.33, 2.40], shorter in women (2.04; 95% CI: 2.00, 2.08) compared to men (2.83; 95% CI: 2.78, 2.89). Half-lives varied when stratified by some contributing factors, with faster excretion rates in nonsmokers and nonalcohol drinkers (especially in males).

CONCLUSIONS

This study, to our knowledge the largest on PFOA half-life, provides precise estimates in young adults whose exposure via drinking water has largely ceased. For other PFAS, longer half-lives than reported in other studies can be explained by some ongoing exposure to PFAS via other routes. https://doi.org/10.1289/EHP13152.

Low concentrations of perfluoroalkyl acids (PFAAs) in municipal drinking water associated with serum PFAA concentrations in Swedish adolescents

While highly contaminated drinking water (DW) is a major source of exposure to perfluoroalkyl acids (PFAAs), the contribution of low-level contaminated DW (i.e. < 10 ng/L of individual PFAAs) to PFAA body burdens has rarely been studied. To address this knowledge gap, we evaluated the association between concentrations of perflurooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS), and their sum (∑4PFAAs) in DW and serum in Swedish adolescents using weighted least squares regression. We paired serum PFAA concentrations in adolescents (age 10-21 years, n = 790) from the dietary survey Riksmaten Adolescents 2016-17 (RMA) with mean PFAA concentrations in water samples collected in 2018 from waterworks (n = 45) supplying DW to the participant residential and school addresses. The median concentrations of individual PFAAs in DW were < 1 ng/L. Median concentrations of PFNA and PFHxS in serum were < 1 ng/g, while those of PFOA and PFOS were 1-2 ng/g. Significant positive associations between PFAA concentrations in DW and serum were found for all four PFAAs and ∑4PFAAs, with estimated serum/DW concentration ratios ranging from 210 (PFOA) to 670 (PFHxS), taking exposure from sources other than DW (background) into consideration. The mean concentrations of PFHxS and ∑4PFAA in DW that would likely cause substantially elevated serum concentrations above background variation were estimated to 0.9 ng/L and 2.4 ng/L, respectively. The European Food Safety Authority has determined a health concern concentration of 6.9 ng ∑4PFAAs/mL serum. This level was to a large degree exceeded by RMA participants with DW ∑4PFAA concentrations above the maximum limits implemented in Denmark (2 ng ∑4PFAAs/L) and Sweden (4 ng ∑4PFAAs/L) than by RMA participants with DW concentrations below the maximum limits. In conclusion, PFAA exposure from low-level contaminated DW must be considered in risk assessment for adolescents.

Mixtures of per- and poly-fluoroalkyl substances (PFAS) reduce the in vitro activation of human T cells and basophils

In the last decades, per- and poly-fluoroalkyl substances (PFAS), widely used industrial chemicals, have been in the center of attention because of their omnipotent presence in water and soils worldwide. Although efforts have been made to substitute long-chain PFAS towards safer alternatives, their persistence in humans still leads to exposure to these compounds. PFAS immunotoxicity is poorly understood as no comprehensive analyses on certain immune cell subtypes exist. Furthermore, mainly single entities and not PFAS mixtures have been assessed. In the present study we aimed to investigate the effect of PFAS (short-chain, long-chain and a mixture of both) on the in vitro activation of primary human immune cells. Our results show the ability of PFAS to reduce T cells activation. In particular, exposure to PFAS affected T helper cells, cytotoxic T cells, Natural Killer T cells, and Mucosal associated invariant T (MAIT) cells, as assessed by multi-parameter flow cytometry. Furthermore, the exposure to PFAS reduced the expression of several genes involved in MAIT cells activation, including chemokine receptors, and typical proteins of MAIT cells, such as GZMB, IFNG and TNFSF15 and transcription factors. These changes were mainly induced by the mixture of both short- and long-chain PFAS. In addition, PFAS were able to reduce basophil activation induced by anti-FcεR1α, as assessed by the decreased expression of CD63. Our data clearly show that the exposure of immune cells to a mixture of PFAS at concentrations mimicking real-life human exposure resulted in reduced cell activation and functional changes of primary innate and adaptive human immune cells.

Association of perfluoroalkyl substances with pulmonary function in adolescents (NHANES 2007-2012)

Perfluoroalkyl substances (PFASs) constitute an environmentally persistent and widespread class of anthropogenic chemicals that have been used in industrial and commercial applications in the USA and around the world. Animal studies suggested its toxic impact on lung development, but the adverse effect of PFAS exposure on childhood pulmonary function has not been clearly determined. We investigated the potential cross-sectional association of environmental PFAS exposures with pulmonary function in 765 adolescents aged 12-19 years from the US National Health and Nutrition Examination Survey (NHANES) 2007-2012. Exposure to PFASs was estimated by measuring serum concentrations, and pulmonary function was assessed by spirometry. Linear regression and weighted quantile sum (WQS) regression were performed to estimate the associations of individual chemicals and chemical mixtures with pulmonary function. Median concentrations of PFOA, PFOS, PFNA, and PFHxS (detection frequencies > 90%) were 2.70, 6.40, 0.98, and 1.51 ng/mL, respectively. No associations were found between the four individual congeners and Σ₄PFASs and the pulmonary function measures in total adolescents. Sensitive analyses were further conducted stratified by age (12-15 and 16-19 years) and sex (boys and girls). In adolescents aged 12-15 years, PFNA was negatively associated with FEV₁:FVC (p-trend = 0.007) and FEF_25-75% (p-trend = 0.03) among girls, while PFNA was positively associated with FEV₁: FVC (p-trend = 0.018) among boys. No associations were found among adolescents aged 16-19 years, either boys or girls. The aforementioned associations were confirmed when further applying WQS models, and PFNA was identified to be the most heavily weighing chemical. Our results suggested that environmental exposure to PFNA may affect pulmonary function among adolescents aged 12-15 years. Given the cross-sectional analysis and less consistent results, further replications of the association in large prospective cohort studies are warranted.

Quantitative relationships of perfluoroalkyl acids in drinking water associated with serum concentrations above background in adults living near contamination hotspots in Sweden

Contaminated drinking water (DW) is a major source of exposure to per- and polyfluoroalkyl substances (PFAS) at locations around PFAS production/use facilities and military airports. This study aimed to investigate quantitative relationships between concentrations in DW and serum of nine perfluoroalkyl acids (PFAAs) in Swedish adult populations living near contamination hotspots. Short-chained (PFPeA, PFHxA, PFHpA, and PFBS) and long-chained PFAAs (PFOA, PFNA, PFDA, PFHxS and PFOS) were measured in DW and serum. We matched DW and serum concentrations for a total of 398 subjects living or working in areas receiving contaminated DW and in one non-contaminated area. Thereafter, linear regression analysis with and without adjustments for co-variates was conducted. This enabled to derive (i) serum concentrations at background exposure (C_B) from sources other than local DW exposure (i.e. food, dust and textiles) at 0 ng/L DW concentration, (ii) population-mean PFAA serum:water ratios (SWR) and (iii) PFAA concentrations in DW causing observable elevated serum PFAA concentrations above background variability. Median concentrations of the sum of nine PFAAs ranged between 2.8 and 1790 ng/L in DW and between 7.6 and 96.9 ng/mL in serum. DW concentration was the strongest predictor, resulting in similar unadjusted and adjusted regression coefficients. Mean C_B ranged from <0.1 (PFPeA, PFHpA, PFBS) to 5.1 ng/mL (PFOS). Serum concentrations increased significantly with increasing DW concentrations for all PFAAs except for PFPeA with SWRs ranging from <10 (PFHxA, PFHpA and PFBS) to 111 (PFHxS). Observed elevated serum concentrations above background variability were reached at DW concentrations between 24 (PFOA) and 357 ng/L (PFHxA). The unadjusted linear regression predictions agreed well with serum concentrations previously reported in various populations exposed to low and high DW levels of PFOA, PFHxS and PFOS. The quantitative relationships derived herein should be helpful to translate PFAA concentrations in DW to concentrations in serum at the population level.

Pathways to Identify Electrophiles In Vivo Using Hemoglobin Adducts: Hydroxypropanoic Acid Valine Adduct and Its Possible Precursors

Analytical methods and tools for the characterization of the human exposome by untargeted mass spectrometry approaches are advancing rapidly. Adductomics methods have been developed for untargeted screening of short-lived electrophiles, in the form of adducts to proteins or DNA, in vivo. The identification of an adduct and its precursor electrophile in the blood is more complex than that of stable chemicals. The present work aims to illustrate procedures for the identification of an adduct to N-terminal valine in hemoglobin detected with adductomics, and pathways for the tracing of its precursor and possible exposure sources. Identification of the adduct proceeded via preparation and characterization of standards of adduct analytes. Possible precursor(s) and exposure sources were investigated by measurements in blood of adduct formation by precursors in vitro and adduct levels in vivo. The adduct was identified as hydroxypropanoic acid valine (HPA-Val) by verification with a synthesized reference. The HPA-Val was measured together with other adducts (from acrylamide, glycidamide, glycidol, and acrylic acid) in human blood (n = 51, schoolchildren). The HPA-Val levels ranged between 6 and 76 pmol/g hemoglobin. The analysis of reference samples from humans and rodents showed that the HPA-Val adduct was observed in all studied samples. No correlation of the HPA-Val level with the other studied adducts was observed in humans, nor was an increase in tobacco smokers observed. A small increase was observed in rodents exposed to glycidol. The formation of the HPA-Val adduct upon incubation of blood with glycidic acid (an epoxide) was shown. The relatively high adduct levels observed in vivo in relation to the measured reactivity of the epoxide, and the fact that the epoxide is not described as naturally occurring, suggest that glycidic acid is not the only precursor of the HPA-Val adduct identified in vivo. Another endogenous electrophile is suspected to contribute to the in vivo HPA-Val adduct level.

Long-distance transport of per- and polyfluoroalkyl substances (PFAS) in a Swedish drinking water aquifer

Use of per- and polyfluoroalkyl substance (PFAS)-containing aqueous film-forming foams (AFFF) at firefighting training sites (FFTS) has been linked to PFAS contamination of drinking water. This study investigated PFAS transport and distribution in an urban groundwater aquifer used for drinking water production that has been affected by PFAS-containing AFFF. Soil, sediment, surface water and drinking water were sampled. In soil (n = 12) at a FFTS with high perfluorooctane sulfonate (PFOS) content (87% of ∑PFAS), the ∑PFAS concentration (n = 26) ranged from below detection limit to 560 ng g^-1 dry weight. In groundwater (n = 28), the ∑PFAS concentration near a military airbase FFTS reached 1000 ng L^-1. Principal component analysis (PCA) identified the military FFTS as the main source of PFAS contamination in drinking water wellfields >10 km down-gradient. Groundwater samples taken close to the military FFTS site showed no ∑PFAS concentration change between 2013 and 2021, while a location further down-gradient showed a transitory 99.6% decrease. Correlation analysis on PFAS composition profile indicated that this decrease was likely caused by dilution from an adjacent conflating aquifer. ∑PFAS concentration reached 15 ng L^-1 (PFOS 47% and PFHxS 41% of ∑PFAS) in surface river water (n = 6) and ranged between 1 ng L^-1 and 8 ng L^-1 (PFHxS 73% and PFBS 17% of ∑PFAS) in drinking water (n = 4). Drinking water had lower PFAS concentrations than the wellfields due to PFAS removal at the water treatment plant. This demonstrates the importance of monitoring PFAS concentrations throughout a groundwater aquifer, to better understand variations in transport from contamination sources and resulting impacts on PFAS concentrations in drinking water extraction areas.

Longitudinal Changes in Maternal Serum Concentrations of Per- and Polyfluoroalkyl Substances from Pregnancy to Two Years Postpartum

Exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy and lactation is of increasing public health concern, but little is known about longitudinal changes in maternal PFAS concentrations from pregnancy to a few years postpartum. We quantified 11 PFAS in 251 serum samples prospectively collected from 42 Northern California mothers during the first, second, and third trimesters of pregnancy and at 3, 6, and 24 months after delivery over 2009-2017. We fit separate linear mixed models during pregnancy, early postpartum, and late postpartum to estimate percent changes of PFAS for each subperiod. Among five PFAS detected in more than 99% of samples, linear and branched perfluorooctanesulfonate (n- and Sm-PFOS), linear perfluorooctanoate (n-PFOA), and perfluorononanoate (PFNA) concentrations changed -4% to -3% per month during pregnancy. During early postpartum, perfluorohexanesulfonate (PFHxS) and n-PFOA concentrations changed -6% and -5%, respectively, per month, and Sm-PFOS and PFNA concentrations changed -1% per month. During late postpartum, n-PFOS, Sm-PFOS, and PFNA concentrations changed -1% per month. Breastfeeding duration was the primary determinant of n-PFOA and PFNA concentrations during late postpartum, showing negative associations. Our findings might be useful for reconstructing reliable prenatal or early life PFAS exposures for offspring.

Demographic, life-style and physiological determinants of serum per- and polyfluoroalkyl substance (PFAS) concentrations in a national cross-sectional survey of Swedish adolescents

PER: and polyfluoroalkyl substances (PFAS) may affect adolescent health, yet factors related to PFAS concentrations in serum are poorly understood. We studied demographic, life-style and physiological determinants of serum PFAS concentrations in Swedish adolescents from a nation-wide survey, Riksmaten Adolescents 2016-17 (RMA, age 10-21 years, n = 1098). Serum samples were analyzed for 42 PFAS, using liquid chromatography-tandem mass spectrometry. The cumulative probability model was used to estimate associations between serum PFAS and determinants, using ordinal logistic regression. Legacy linear (lin-) perfluorooctanoic acid (PFOA), perfluorononaoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), lin-perfluorohexanesulfonic acid (PFHxS) and lin-/branched (br-) perfluorooctanesulfonic acid (PFOS) were quantifiable in ≥70% of the samples. The emerging PFAS 9-chlorohexanedecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) was quantified in 5.4% of the samples, suggesting initiation of long-range transport far from production sites. Median concentrations of all legacy PFAS were <2 ng/g serum, with a few participants having very high (>100 ng/g serum) lin-PFHxS and lin-/br-PFOS concentrations due to previous high exposure from PFAS-contaminated drinking water. Legacy PFAS exposure was strongly associated with birth country of the participants and their mothers. 2-fold higher estimated adjusted mean (EAM) concentrations were seen among high income country participants with mothers from high income countries than among low/lower-middle income country participants with mothers from the same category. Menstruating females had lower br-PFOS EAM concentrations than those who were not. Iron status (plasma ferritin) among females may be a marker of intensity of menstrual bleeding, but it was not significantly associated with legacy PFAS concentrations among females. Further studies are needed to determine how physiological changes occurring around menstruation affect the toxicokinetics of PFAS in females. In conclusion, PFAS are pollutants of the industrialized world and some of the identified determinants may be overlooked confounders/effect modifiers that should be included in future PFAS/health studies among adolescents.

Determinants of serum half-lives for linear and branched perfluoroalkyl substances after long-term high exposure-A study in Ronneby, Sweden

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent substances with surfactant and repellent properties. Municipal drinking water contaminated with PFAS had been distributed for decades to one third of households in Ronneby, Sweden. The source was firefighting foam used in a nearby airfield since the mid-1980s. Clean water was provided from December 16, 2013.

AIMS

The purpose was to estimate serum half-lives and their determinants in the study population for different PFAS.

METHODS

Up to ten blood samples were collected between 2014 and 2018 from 114 participants (age 4-84 years at entry, 53% female). 19 PFAS were analysed. Linear mixed models were used to estimate the half-lives.

RESULTS

Eight PFAS were increased in Ronneby: perfluorooctanoic acid (PFOA), perfluoropentane sulfonate (PFPeS), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS), linear perfluorooctane sulfonate (L-PFOS) and three branched perfluorooctane sulfonates (1 m-PFOS, 3/4/5m-PFOS and 2/6m-PFOS). The mean estimated half-lives (in years) were 0.94 (95 %CI 0.86-1.02) for PFPeS, 2.47 (2.27-2.7) for PFOA, 2.67 (2.51-2.85) for 2/6m-PFOS, 2.73 (2.55-2.92) for L-PFOS, 3.43 (3.19-3.71) for 3/4/5m-PFOS, 4.52 (4.14-4.99) for PFHxS, 4.55 (4.14-5.06) for PFHpS, and 5.01 (4.56-5.55) for 1 m-PFOS. The most important determinants of a shorter half-life were young age, and better kidney function measured by estimated glomerular filtration rate and ratio of paired urine and serum PFAS levels, followed by female sex during their fertile period aged 15-50. Markers of gut inflammation and reduced permeability i.e. zonulin and calprotectin were also possibly associated with shorter half-life. The results also suggested a time-dependent PFAS elimination process, with more rapid elimination in the first year after the end of exposure.

CONCLUSION

The half-life estimates are in line with past estimates for some PFAS such as PFOA, and the novel results for different PFOS isomers. These results provide observational support for elimination routes - renal, fecal and maternal.

The methylimidazolium ionic liquid M8OI is detectable in human sera and is subject to biliary excretion in perfused human liver

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M8OI was recently found to be contaminating the environment.

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M8OI was detected in the sera from 5/20 PBC patients and 1/10 controls.

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M8OI is taken up by human liver hepatocytes.

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M8OI is sequentially metabolised by CYPs followed by oxidation by dehydrogenases.

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The final carboxylic acid metabolite COOH7IM is, in part, excreted into human bile.

A methylimidizolium ionic liquid (M8OI) was recently found to be contaminating the environment and to be related to and/or potentially a component of an environmental trigger for the autoimmune liver disease primary biliary cholangitis (PBC). The aims of this study were to investigate human exposure to M8OI, hepatic metabolism and excretion. PBC patient and control sera were screened for the presence of M8OI. Human livers were perfused with 50μM M8OI in a closed circuit and its hepatic disposition examined. Metabolism was examined in cultured human hepatocytes and differentiated HepaRG cells by the addition of M8OI and metabolites in the range 10–100 μM. M8OI was detected in the sera from 5/20 PBC patients and 1/10 controls. In perfused livers, M8OI was cleared from the plasma with its appearance – primarily in the form of its hydroxylated (HO8IM) and carboxylated (COOH7IM) products – in the bile. Metabolism was reflected in cultured hepatocytes with HO8IM production inhibited by the cytochrome P450 inhibitor ketoconazole. Further oxidation of HO8IM to COOH7IM was sequentially inhibited by the alcohol and acetaldehyde dehydrogenase inhibitors 4-methyl pyrazole and disulfiram respectively. Hepatocytes from 1 donor failed to metabolise M8OI to COOH7IM over a 24 h period. These results demonstrate exposure to M8OI in the human population, monooxygenation by cytochromes P450 followed by alcohol and acetaldehyde dehydrogenase oxidation to a carboxylic acid that are excreted, in part, via the bile in human liver.

Per- and polyfluoroalkyl substances and their alternatives in paper food packaging

Per- and polyfluoroalkyl substances (PFAS) have been used in food contact paper and paperboard for decades due to their unique ability to provide both moisture and oil/grease resistance. Once thought to be innocuous, it is now clear that long chain PFAS bioaccumulate and are linked to reproductive and developmental abnormalities, suppressed immune response, and tumor formation. Second-generation PFAS have shorter biological half-lives but concerns about health risks from chronic exposure underscore the need for safe substitutes. Waxes and polymer film laminates of polyethylene, poly(ethylene-co-vinyl alcohol), and polyethylene terephthalate are commonly used alternatives. However, such laminates are neither compostable nor recyclable. Lamination with biodegradable polymers, including polyesters, such as polylactic acid (PLA), polybutylene adipate terephthalate, polybutylene succinate, and polyhydroxyalkanoates, are of growing research and commercial interest. PLA films are perhaps the most viable alternative, but performance and compostability are suboptimal. Surface sizings and coatings of starches, chitosan, alginates, micro- and nanofibrilated cellulose, and gelatins provide adequate oil barrier properties but have poor moisture resistance without chemical modification. Plant proteins, including soy, wheat gluten, and corn zein, have been tested as paper coatings with soy being the most commercially important. Internal sizing agents, such as alkyl ketene dimers, alkenyl succinic anhydride, and rosin, improve moisture resistance but are poor oil/grease barriers. The difficulty in finding a viable replacement for PFAS chemicals that is cost-effective, fully biodegradable, and environmentally sound underscores the need for more research to improve barrier properties and process economics in food packaging products.

Serum perfluoroalkyl substances in residents following long-term drinking water contamination from firefighting foam in Ronneby, Sweden

BACKGROUND

In December 2013, it was discovered that drinking water supplied to one third of the households in Ronneby, southern Sweden, was highly contaminated by PFAS (sum level >10,000 ng/L) originated from firefighting foams used at a nearby military airport.

OBJECTIVES

To report serum PFAS levels of Ronneby residents participating in a biomonitoring program, and to describe the variation by age, sex and calendar period for residential exposure. In addition, a reference group living in a neighboring municipality without PFAS contaminated drinking water was examined.

METHODS

Blood samples and demographic data were collected for 3297 Ronneby residents and 226 individuals from the reference group. Yearly residence addresses were available for 3086 Ronneby residents from the national population registry. Serum concentrations of PFHxS, PFOS and PFOA were determined in all participants, with additional PFHpA, PFNA and PFDA in subsets of the participants.

RESULTS

The population geometric means for serum PFHxS, PFOS and PFOA were 114, 135 and 6.8 ng/mL for all Ronneby residents, i.e.135, 35 and 4.5 times higher than for the reference group. Ronneby residents who resided in the area with contaminated water supply during 2005-2013 showed much higher PFAS levels in 2014 than those exposed only before 2005. Ronneby residents who never resided in the area with contaminated water supply also had higher serum PFAS levels than the reference group. All three PFAS were highly correlated (r_s > 0.9 for each pair). Serum PFAS levels were lowest in teenage years and then increased with age. Adult females had lower PFAS levels on average than males under the age of 60 but higher above 60.

DISCUSSION

The results reveal high serum PFAS levels dominated by PFHxS and PFOS in the Ronneby residents highly exposed to PFAS originated from firefighting foams. The PFAS exposure in Ronneby permits studies of associations to a range of health parameters, as well as studies of the toxicokinetics of PFAS exposure.

Human biomonitoring of per- and polyfluoroalkyl substances in German blood plasma samples from 1982 to 2019

The findings of per- and polyfluoroalkyl substances (PFAS) in humans and the environment all over the world have raised concerns and public awareness for this group of man-made chemicals. In the last three decades, this led to different regulatory restrictions for specific PFAS as well as shifts in the production and usage of these substances. In this study, we analyzed the PFAS levels of 100 human blood plasma samples collected from 2009 to 2019 for the German Environmental Specimen Bank (ESB) to further elucidate the time course of exposure towards this substance group as shown by Schröter-Kermani et al., (2013) with samples from 1982 to 2010. A spectrum of 37 PFAS, including perfluorocarboxylic (PFCA) and -sulfonic acids (PFSA) as well as potential precursors and substitutes like ADONA, GenX or F-53B was analyzed by UHPLC coupled with high-resolution mass spectrometry. Validation was successful for 33 of the substances. The two legacy substances perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were detected in every sample of the 2009-2019 dataset and showed the highest concentrations with ranges of 0.27-14.0 ng/mL and 1.21-14.1 ng/mL, respectively. A significant portion of total PFOS analytes was present as branched isomers (mean: 34 ± 7%). High detection frequencies of 95% and 82% were also found for perfluorohexane sulfonic acid (PFHxS) and perfluorononanoic acid (PFNA), respectively, but in lower concentrations (PFHxS: <LOQ - 4.62 ng/mL; PFNA: <LOQ - 3.66 ng/mL) than PFOA and PFOS. Besides other PFCA and PFSA only 8:2 fluorotelomer sulfonic acid (8:2 FtS) and N-methyl perfluorooctane sulfonamidoacetic acid were detected in very few samples. In combination with the previous results from 1982 to 2010, declining temporal trends were observed for all PFAS (PFOA, PFNA, PFHxS, and PFOS) frequently detected in the ESB samples. The results of this study indicate a decrease in human exposure to known PFAS in Germany over the last three decades and emphasize the importance of long-term human biomonitoring studies for investigating the effects of chemical regulation.

Transfer of Per- and Polyfluoroalkyl Substances (PFAS) from Feed into the Eggs of Laying Hens. Part 1: Analytical Results Including a Modified Total Oxidizable Precursor Assay

The group of per- and polyfluoroalkyl substances (PFAS) comprises thousands of chemicals, which are used in various industrial applications and consumer products. In this study, a feeding experiment with laying hens and feed grown on a contamination site was conducted, and PFAS were analyzed in the feed and eggs to assess the transfer of PFAS into eggs. A targeted analysis of perfluoroalkyl acids (PFAAs) and different sulfonamides was performed. Additionally, the total oxidizable precursor (TOP) assay was modified by fully oxidizing small amounts of the samples instead of oxidizing their extracts in order to overcome potential losses during extraction. Targeted analysis showed the presence of known PFAAs and four sulfonamides in the feed and egg yolk samples. In the plant-based feed, short-chain PFAAs, methyl and ethyl perfluorooctane sulfonamidoacetic acid (Me- and EtFOSAA), and perfluorooctane sulfonic acid (PFOS) were the most abundant PFAS. In the eggs, PFOS, FOSAA, and its alkylated homologues showed the highest concentrations. The TOP assay revealed the presence of substantial amounts of precursors with different chain lengths from C4 to C8. The highest relative increase of PFOA after oxidation was observed in egg yolk from the end of the exposure period (828%). The results of this study demonstrate the transfer of PFAAs and their precursors into hens' eggs and emphasize the contribution of (known and unidentified) precursors to the overall PFAS burden in edible products. The modified TOP assay approach was shown to be a powerful tool to better assess the total burden of samples with PFAS.

Prevalence of per- and polyfluoroalkyl substances (PFASs) in drinking and source water from two Asian countries

The present study focuses on the determination of the occurrence and levels of per- and polyfluoroalkyl substances (PFASs) in the drinking and source water from the Philippines and Thailand. A total of 46 samples (18 commercial bottled waters, 5 drinking water from vending machine (re-fill stations) and 23 source water) were analyzed using liquid chromatography with tandem high-resolution mass spectrometry. Using the targeted method, 12 different PFASs were detected in the drinking water samples with total quantifiable PFASs (∑PFASs) levels ranging from 7.16 to 59.49 ng/L; 15 PFASs were detected in source water with ∑PFASs ranging from 15.55 to 65.65 ng/L. A 100% detection frequency was observed for perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorosulfonic acid (PFOS) in all water samples. Six other PFASs, not included in the targeted analysis, were detected using the suspect screening approach. For the first time, the presence of 2-(N-methylperfluorooctanesulfonamido) acetic acid (N-MeFOSAA) in drinking water is reported, and 3 novel PFASs (C₅H₅OF_8, C₆H₄O₂F₆, and C₉H₂O₂F₁₆) were detected using suspect screening in source water. Combined results from target and suspect screening analysis showed that PFASs detected were predominantly (52%) short-chain (with fluorinated alkyl chain of ≤6) which could be explained by their high mobility in the environment. The detected PFASs levels in drinking water will not likely pose immediate health risk to consumers according to US EPA health advisory for PFOS and PFOA of 70 ng/L, but inclusion of bottled and drinking water from re-fill stations in monitoring programs is warranted.