Internal exposure to perfluoroalkyl substances (PFASs) and biological markers in 101 healthy 1-year-old children: associations between levels of perfluorooctanoic acid (PFOA) and vaccine response

Per- and polyfluoroalkyl substances (PFAS), thyroid hormones, sexual hormones and pubertal development in adolescents residing in the neighborhood of a 3M factory

BACKGROUND

Near Antwerp a 3M factory has been active since 1971 emitting PFAS, mainly PFOS, in the local environment. Production of C8 compounds was stopped in 2002, production of other PFAS continued until 2024. This study aimed to examine the association between internal PFAS concentrations and thyroid hormones, sexual hormones, and pubertal development in adolescents living in the neighborhood of the factory.

METHODS

We measured PFAS in serum of 146 female and 139 male adolescents. For males sex hormones (LH, testosterone, estradiol, progesterone, inhibin B, FSH) and SHBG were measured in serum. For males and females we assessed serum thyroid hormone levels (TSH, T3, T4 and T3/T4) and pubertal development parameters self-assessed through a standardized questionnaire. Associations between PFAS concentrations and effect biomarkers/health effects were assessed through Generalized Estimating Equations (GEE), using linear models for continuous outcomes, logistic models for binary outcomes, and proportional odds models for ordinal outcomes.

RESULTS

For males LH, total and bioavailable testosterone showed significant negative associations with PFHxS and PFOA. LH and bioavailable testosterone also showed significant negative associations with other PFAS compounds. SHBG showed significant positive associations with PFDA, PFNA, PFHxS, PFOS and the sum of the linear forms of PFOS, PFOA, PFNA and PFHxS. Males' length and growth spurt showed significant negative associations with PFOS, PFOA and PFAS sum parameters and length and growth spurt separately also with other PFAS compounds. For females growth spurt showed significant negative association with PFOA and a significant positive association with PFOS(branched). For both males and females body hair development showed significant negative associations with PFHxS, and, for males and females separately also with other PFAS compounds. For females, breast development showed significant negative associations with PFOA, pubertal development scale showed significant negative associations with PFOA, PFHxS, PFOS(linear) and the sum of 4 PFAS. For males, TSH showed a significant negative association with PFDA and FT3 showed significant positive associations with PFOA, PFOA and PFNA. For females, FT3 showed a significant negative association with PFOS(branched).

CONCLUSION

We observed significant, consistent and biologically relevant associations of PFAS serum concentrations with sex hormone and SHBG levels in male adolescents. Moreover, a significant delay in physiological processes occurring in puberty was observed in females and males. Associations with thyroid hormones differed significantly by sex.

Concentrations of perfluoroalkyl substances in sediments and wastewater treatment plant-derived biosolids from Ireland

Concentrations of 39 perfluoroalkyl substances (PFAS) are reported in 120 inland and transitional sediments from Ireland. We also report concentrations in 21 samples of biosolids from seven Irish wastewater treatment plants (WWTPs; n = 3 from each). This is the first report of the presence (% detection frequency) in sediments of: perfluroroundecane sulfonate (PFUdS) (7.4 %), perflurorododecane sulfonate (PFDoS) (8.6 %), perfluorotridecane sulfonate (PFTrDS) (7.4 %), 11-chloroeicosafluoro-3-oxaundecane-1-sulfonate (11Cl-PF3OUdS or 8:2 Cl-PFESA) (7.4 %), and 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (9Cl-PF3ONS or 6:2 Cl-PFESA) (2.5 %) and of the following in biosolids: PFDoS (24 %), PFTrDS (38 %), and perfluoroethylcyclohexane sulfonate (PFECHS) (38 %). Concentrations of all target PFAS in biosolids exceed significantly (p < 0.05) those in sediments. Moreover, the relative abundance of different PFAS classes differs markedly. In sediments, perfluorocarboxylic acids (PFCAs) dominate (on average 55 % ΣPFAS), while in biosolids, PFCAs constitute on average 26 % ΣPFAS, with perfluorosulfonic acids (PFSAs) the main group (37 % ΣPFAS). This suggests PFAS in Irish sediments are a complex integral of many sources, of which WWTPs are just one. Concentrations in sediments were assessed for ecotoxicity by comparison with predicted no effect concentration (PNEC) values promulgated by the NORMAN network. In general, concentrations detected are well below PNECs. However, the PNEC for perfluorooctane sulfonic acid (PFOS) is exceeded for most sediments. While overall, novel PFAS (nPFAS) like sodium 2,2,3-trifluor-3-(1,1,2,2,3,3-hexafluoro-3-trifluormethoxypropoxy) propionate (ADONA), PFECHS, and 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoic acid (HFPO-DA aka Gen-X) are present in low abundance in biosolids and sediments; 11Cl-PF3OUdS (90 % ΣPFAS) dominates one sediment, while two other sediments contain Gen-X at 59 and 69 % ΣPFAS respectively. This suggests unidentified local sources of these nPFAS at those sites.

Accumulation of per- and polyfluoroalkyl substances (PFAS) in tissues of wild boar (Sus scrofa)

The widespread application of per- and polyfluoroalkyl substances (PFAS) resulted in ubiquitous environmental contamination. Understanding the PFAS tissue distribution in mammals and humans is crucial for the assessment of potential health risks. The levels of eleven PFAS were determined by UPLC-MS/MS in plasma and various tissues of wild boar (n = 82) hunted in Germany. The most prevalent PFAS (PFOA, PFNA, PFHxS and PFOS) were detected in all analyzed samples. The median level of the sum (Σ 4PFAS) was highest in liver (90.2 μg/kg), followed by kidney (9.45 μg/kg), plasma (7.63 μg/L), lung (6.84 μg/kg), heart muscle (2.60 μg/kg), spleen (2.46 μg/kg), and skeletal muscle (1.03 μg/kg). Consumption of a single portion (125 g) of liver containing the Σ 4PFAS median level would result in a 36.6-fold exceedance of the tolerable weekly intake (TWI) of EFSA in a 70 kg-person. The accumulation (calculated as tissue/plasma ratio) of perfluoroalkyl carboxylic acids with ηpfc = 8-13 in lung, spleen, muscle and heart tissues increased with molecule size, indicating passive mechanisms of distribution driven by hydrophobicity. In contrast, liver and kidney distribution coefficients scattered, indicating additional involvement of chain-length dependent active transport processes. The highest accumulation was observed for PFOS in the liver (median tissue/plasma ratio 18.0). The shortest PFAS included in the study (PFHxA, PFHpA, PFOA, PFBS and PFHxS) did not accumulate in any of the tissues, probably due to strong binding to blood proteins like serum albumin and their relative polarity impeding passive membrane diffusion.

Per- and polyfluoroalkyl substances (PFAS): immunotoxicity at the primary sites of exposure

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic chemicals widely used in industrial and consumer products, leading to environmental contamination and human exposure. This review focuses on perfluoroalkyl acids, a subset of PFAS, which are primarily encountered through diet, including drinking water, and other pathways such as dust ingestion, and dermal contact. Impaired vaccine antibody response has been identified as the most critical effect for risk assessment by the European Food Safety Authority. Furthermore, human epidemiological studies have linked exposure to certain PFAS to various immune-related outcomes, such as asthma, allergies, and inflammatory bowel disease. This review examines potential immunomodulatory effects of perfluoroalkyl acids at the primary sites of exposure: lungs, intestines, and skin, using human epidemiological data as the basis for investigating these impacts. While animal studies are referenced for context, this paper highlights the need for further human-based research to address key questions about PFAS and their immunological impacts. The state of in vitro toxicity testing related to these effects is thoroughly reviewed and critical issues pertaining to this topic are discussed.

United States Environmental Protection Agency's Perfluorooctanoic Acid, Perfluorooctane Sulfonic Acid, and Related Per- and Polyfluoroalkyl Substances 2024 Drinking Water Maximum Contaminant Level: Part 2 - Fifteen Misconceptions About the Health Hazards

This paper examines widely held beliefs about the six per- and polyfluoroalkyl substances (PFAS) addressed in the final U.S. Environmental Protection Agency's (EPA) rule on PFAS in drinking water (e.g., the Maximum Contaminant Levels - MCLs). Based on our understanding of the scientific literature and the comments submitted by stakeholders regarding the EPA's regulation that was promulgated in April 2024, we identified 15 misconceptions that had a weak scientific foundation. These are now memoralized in the MCLs for the six PFAS but remain debated due to ongoing ambiguous research findings. Many critics of the MCLs found the EPA's systematic review of the published relevant information, particularly the toxicology of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), to be inadequate. The following seven views are among the most important. First, the EPA asserted that the toxicology of these six chemicals was poorly understood and lacked sufficient data to determine a safe daily intake level for chronic health effects; nonetheless, they promulgated what may be the costliest environmental regulation to date. Notably, adverse effects remain difficult to demonstrate in occupationally exposed individuals even at blood concentrations 50-100 times higher than current background PFAS levels. Second, the Agency indicated that the epidemiology data showed that exposure to PFOA and PFOS caused kidney and potentially other cancers, yet the data were equivocal and do not support that assertion. Third, it was stated that specific non-cancer effects, such as heart disease, would be prevented under the promulgated rule; however, the studies that they relied upon do not show an increased incidence of heart disease even in highly exposed populations. Fourth, the Agency relied on animal data to support its views on the likely toxic effects in humans, despite ample toxicology data that animals, particularly rodents, are poor predictors of the human response to PFAS exposures. Fifth, the EPA predicted a reduction in healthcare expenditures that would offset much of the cost of complying with the MCL, but, they did not have adequate data to support this prediction. Sixth, the EPA suggested that these six PFAS act through a shared mechanism of action (i.e., PPARα pathway induction); however, data indicate that PPARα induction in humans may be 80% less than what is observed in rodents. Also, induction of the PPARα pathway is not a cause of systemic disease. Seventh, the Agency failed to disclose that achieving the new MCL would yield negligible reductions in blood PFAS levels even among highly exposed populations, given drinking water accounts for only 20% or less of total PFAS exposure. The survey that could answer that question, the EPA's fifth Unregulated Contaminant Monitoring Rule, was only 25% complete at the time the MCL was promulgated. Overall, our analysis concluded that while the EPA's intent to regulate these chemicals due to their environmental presence was necessary, the derivation of the MCLs and the alleged health effects was based on the application of the precautionary principle rather than robust scientific evidence.

PFAS drinking water treatment trade-offs: comparing the health burden of GAC treatment to the health benefits of reduced PFAS exposure

To protect human health, limits for the concentrations of per- and polyfluoroalkyl substances (PFAS) in drinking water are decreasing in many countries. However, the required treatment to achieve these lower concentrations is more resource and energy intensive than conventional drinking water treatment. Consequently, this intensified water treatment has an indirect negative impact on human health. For example, treatment with granular activated carbon (GAC), commonly used for PFAS removal, can lead to particulate matter emissions and additional global warming. These negative impacts partly off-set the health benefit achieved by lower PFAS exposure via drinking water. In this study, we quantified health impacts of both the increased treatment and the reduced PFAS exposure in disability-adjusted life years (DALYs), to assess whether PFAS removal from drinking water to specified targets with GAC results in a net health benefit. We selected the prospective Dutch drinking water guideline for PFAS of 4.4 ng PFOA-equivalent (PEQ) L-1, as this guideline is amongst the more conservative concentration targets globally. We first conducted a Life Cycle Assessment (LCA) to quantify the health cost associated with the increased reactivation frequency of an existing GAC system in the Netherlands, required to achieve PFAS concentrations below 4.4 ng PEQ L-1. Then, we quantified the health benefit obtained by the corresponding lower PFAS exposure, using pharmacokinetic modelling combined with published dose-response relationships. For the treatment plant investigated in the current study, which uses reactivated wood-based GAC, increasing the reactivation frequency to remove more PFAS was found to result in a net health benefit of 6.9-300 DALYs per 106 persons per year. However, when single-use rather than reactivated GAC would be used for PFAS treatment, the health losses from the GAC production were in the same range as the health benefits from lower PFAS exposure. Overall, the negative health impacts associated with more intensive water treatment should be considered when developing strategies to reduce PFAS exposure.

PFC/PFAS concentrations in human milk and infant exposure through lactation: a comprehensive review of the scientific literature

Per- and polyfluoroalkyl substances (PFAS), previously known as perfluorinated compounds (PFC), are a group of synthetic chemicals widely used over the past decades. Their extensive application, combined with their environmental persistence, has contributed to their ubiquitous presence in the environment and the associated toxicological risks. Regarding humans, blood serum testing remains the primary method for biomonitoring PFAS exposure, while breast milk has also been used due to the transfer of these substances from mothers to infants during lactation. This paper aims to review the scientific literature (using PubMed and Scopus databases) on PFAS concentrations in the breast milk of non-occupationally exposed women. Where available, the estimated daily intake of these compounds by breastfeeding infants is also examined. The reviewed studies are categorized by continent and country/region, revealing a significant lack of data for many countries, including both developed and developing nations. The findings indicate substantial variability in PFAS concentrations, influenced by factors such as geographic location, sampling year, and the specific PFAS analyzed. Among the identified compounds, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are most commonly detected, along with perfluorohexanesulfonic acid (PFHxS) and perfluorononanoic acid (PFNA), being the only PFAS with regulated maximum levels in certain foodstuffs. Most studies were conducted before the implementation of the current (updated) tolerable weekly intake (TWI) values for these substances. Consequently, the majority reported a low health risk for breastfeeding infants, even in high-intake scenarios. Nevertheless, biomonitoring studies are urgently needed in countries with limited or no data, and new investigations should assess whether current estimated intakes exceed the updated TWI. Special focus should be given to rural and industrial areas where exposure levels remain poorly understood.

A review of the occurrence and distribution of Per- and polyfluoroalkyl substances (PFAS) in human organs and fetal tissues

This review synthesizes current evidence on PFAS concentrations across human organs and tissues, excluding blood matrices. Literature search was conducted using PubMed, Web of Science, and Scopus. The earliest reported study on the topic measured PFOS, PFOSA, PFOA, and PFHxS levels in human liver and serum, showing mean liver concentrations of 18.8 ng/g and a liver-to-serum ratio of 1.3:1 for PFOS. Subsequent research extended these findings to other organs, with measurements in pooled samples indicating organ-specific accumulation patterns. PFOS was predominant in liver, kidney, and lung, while PFOA was more prominent in bone. Pathological conditions, such as liver disease, have shown to influence PFAS distribution, with diseased tissues exhibiting altered accumulation patterns. On the other hand, the occurrence of PFAS in fetal and placental tissues demonstrated that these compounds cross the placenta, although fetal exposure levels were significantly lower than maternal levels. Tissue-specific accumulation has been reported, with liver and lung showing higher concentrations compared to other fetal tissues. Associations between PFAS levels in the placenta and birth outcomes indicated potential sex-specific effects, including reduced birth weight in male infants exposed to higher PFOS levels. This review highlights important differences in the detection frequencies and concentrations of PFAS across organs and the specific studies. These variations are attributed to differences in analytical methods, sample characteristics, and exposure sources. The findings underscore the need for standardized methodologies and further research to better understand PFAS distribution in human tissues and their potential health impacts, particularly during critical developmental stages.

Perfluoroalkyl acids interact with major human blood protein fibrinogen: Experimental and computation study

PFAS (per- and polyfluorinated alkyl substances) are synthetic compounds prized for their stability across various industries, but they pose an increasing threat to the environment and human health. Following the regulation of long-chain PFAS, short-chain and ultra-short-chain molecules have been introduced as substitutes, yet their bioaccumulation potential remains poorly understood. In this study, we combined experimental (intrinsic fluorescence, microscale thermophoresis, clotting assays) and computational approaches to investigate how trifluoroacetic acid, perfluorobutanoic acid, and perfluorooctanoic acid bind to fibrinogen, a key human blood protein. All tested perfluoroalkyl acids (PFAAs) exhibited moderate binding affinity (Kd in the 10-4-10-5 M range), yet circular dichroism and fibrin clot formation assays revealed no functional impairment of fibrinogen. Molecular docking indicated distinct, chain-length-specific binding sites, suggesting multiple routes for PFAAs to interact with fibrinogen without disrupting its primary biological role. These findings challenge the assumption that short-chain PFAS are less bioaccumulative and underscore the need for further research into their long-term health impacts, particularly given their widespread presence in the environment and potential accumulation in human blood.

In vitro approaches to investigate the effect of chemicals on antibody production: the case study of PFASs

The increasing variety and quantity of new chemical substances have raised concerns about their potential immunotoxic effects, making it essential to assess their impact on human health. One key concern is the reduction of antibody production, as seen with per- and poly-fluoroalkyl substances (PFASs), commonly known as "forever chemicals." Both in vivo and epidemiological data show that PFASs have immunosuppressive effects, leading to reduced antibody responses, particularly following vaccination. In animal studies, the T cell-dependent (TD) antibody response is the gold standard for assessing chemical effects on immune function. This study utilized two in vitro approaches to investigate the effects of chemicals on antibody production using human peripheral blood mononuclear cells. Initial tests used unstimulated, negative (vehicle), and positive (rapamycin) controls to confirm the robustness of the models. Subsequently, four long-chain PFASs (PFOA, PFOS, PFNA, and PFHxS) were tested. Keyhole limpet hemocyanin (KLH) was used to mimic the TD response, while a TLR9 agonist and IL-2 activated B cells for T cell-independent (TI) immunoglobulin production. The results demonstrated the ability to reproduce TD and TI responses in vitro with robust, reproducible outcomes across a cohort of 20 human donors. The data, consistent with existing literature, showed a significant reduction in anti-KLH IgM production, especially for PFOA in male donors. Similar trends were observed for all PFASs in suppressing total TI IgG and IgM production. These methods closely replicated in vivo conditions, offering a potential alternative to animal models in immunotoxicity assessments.

Prenatal per- and polyfluoroalkyl substances in relation to antibody titers and infections in childhood

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent and ubiquitous chemicals posing environmental and health risks. Impact on the human immune system is of particular concern, especially during fetal immune development. Alterations to fetal immune development can impact immunity later in life, e.g., the response to vaccines and pathogens.

OBJECTIVES

This study investigated the association between PFAS concentrations in healthy pregnant women from Hamburg, Germany, and antibody levels to routine vaccines in childhood and occurrence of childhood infections.

METHODS

Mid-pregnancy serum samples from 152 mothers-child pairs were analyzed for 18 PFAS compounds, and antibody levels to measles, mumps, rubella, diphtheria, and tetanus were assessed at age 5. Maternal questionnaires provided data on childhood infections each year at age 1-5. Linear and Poisson regression models were adjusted for maternal age, education, parity, and breastfeeding duration. Weighted quantile sum (WQS) regression was used to assess the PFAS mixture.

RESULTS

Higher PFAS concentrations were associated with lower antibody titers at age 5 years, particularly for mumps, tetanus, diphtheria, and rubella. Several PFAS were also linked to increased childhood infections, especially respiratory infections, during ages 3 and 4 years. WQS regression revealed a negative association between combined PFAS and tetanus titers.

CONCLUSIONS

Maternal PFAS concentrations during pregnancy are inversely associated with antibody levels in children and positively associated with increased childhood infections, notably respiratory infections. These findings underscore the importance of understanding environmental exposures' impact on immune responses and call for continued monitoring of PFAS in both the environment and human populations to mitigate health risks.

Serum biomonitoring of per- and polyfluoroalkyl substances (PFASs) in the adult population of Switzerland: Results from the pilot phase of the Swiss health study

Monitoring human exposure to per- and polyfluoroalkyl substances (PFASs) is of significant public health relevance, given the documented associations between PFAS exposure and a range of adverse health outcomes. This study aimed to provide a sensitive and reliable analytical approach for the determination of PFASs in human serum and to advance the understanding of PFAS exposure. Serum samples from 630 adult participants from the population-based Swiss Health Study pilot phase were analysed for 30 legacy and emerging PFASs. Quantitative analysis was performed after specific sample preparation using high-performance liquid chromatography coupled to mass spectrometry. The association between PFAS serum concentrations and selected demographic and behavioural parameters of interest was assessed using linear regression. The developed method enabled sensitive high-throughput analysis and resulted in reliable validation parameters and robust quantification performance. The study revealed that, while the prevalence of emerging PFASs was observed to be marginal, legacy PFASs predominated. Perfluorooctane sulfonic acid (PFOS, geometric mean (GM) 6.6 ng/mL), perfluorooctanoic acid (PFOA, GM 1.3 ng/mL) and perfluorohexane sulfonic acid (PFHxS, GM 1.2 ng/mL) were detected in all serum samples and contributed 88 % to the median sum of determined PFASs (10.3 ng/mL). The levels of PFOA and PFOS were found to be associated with age and gender. Furthermore, PFOS levels were associated with consumption of fish, particularly freshwater species, while PFOA levels were negatively associated with the duration of breastfeeding. Regional disparities were also observed. Several results exceeded specific health thresholds for PFAS intake or human biomonitoring, but the observed values were overall comparable to similar studies conducted worldwide. The provision of comprehensive information on a wide range of legacy and emerging PFASs facilitates a more complete identification of possible sources of exposure, not only in the regions concerned, but also beyond, and establishes a robust foundation for the guidance of future investigations.

Maternal exposure to per- and polyfluoroalkyl substances and epitope level antibody response to vaccines against measles and rubella in children from the Boston birth cohort

BACKGROUND

Previous studies suggest that per- and polyfluoroalkyl substances (PFAS) may act as immune suppressants. However, research about the impact of PFAS exposure on antibody responses to the measles, mumps, rubella (MMR) vaccine is limited and inconsistent.

METHODS

This report includes 748 mother-child pairs from the Boston Birth Cohort, with 8 PFAS compounds measured in maternal plasma shortly after delivery. IgG reactivities to measles and rubella were profiled in cord blood and venous blood plasma during early childhood, using Phage ImmunoPrecipitation Sequencing. Linear regression models were applied to assess the relationships between log2-transformed PFAS and IgG reactivities as measured by Viral Aggregate Reactivity score (VARscore, with inverse normal transformation) for measles and rubella. Quantile g-computation was applied to evaluate the PFAS mixture - VARscore associations.

RESULTS

The detection rate for 8 PFAS compounds ranged from 90 % to 100 % in maternal plasma. Maternal PFAS burden score (P = 0.01), but not individual PFAS compounds, was associated with lower VARscore for measles in cord blood. In 348 children after receiving the MMR vaccine, three maternal PFAS compounds (Me-PFOSA-AcOH, PFHpS and PFHxS) were significantly associated with lower measles VARscore (P < 0.05). Me-PFOSA-AcOH and PFHxS were significantly associated with higher risk of having low reactivity to measles defined as VARscore < 25th percentile. PFAS mixture analysis revealed a significant inverse association between quantile of the PFAS mixture and measles VARscore (P = 0.025) in children after vaccination, with PFHxS as an important contributor to this association. These inverse associations were more pronounced in Black children (compared to non-Black children) and in preterm children (compared to term children). In comparison, no associations were found for rubella VARscore.

CONCLUSIONS

This prospective birth cohort study provides suggestive evidence that maternal PFAS exposure is associated with a reduced immune response to the measles vaccine, especially, among Black or preterm children.

Evaluating PFAS-Induced modulation of peripheral blood mononuclear cells (PBMCs) immune response to SARS-CoV-2 spike in COVID-19 Vaccinees

The persistent nature of the environmental contaminants per- and polyfluoroalkyl substances (PFAS) has recently received considerable attention, particularly because of their adverse effects on immune system functionality in the context of vaccine responses to infectious diseases. Following COVID-19 vaccination, some studies have shown a significant negative correlation between serum PFAS concentrations and the humoral immune response to the SARS-CoV-2 spike protein vaccination. However, the influence of PFAS on the cell-mediated immune response to SARS-CoV-2 spike protein post-COVID-19 vaccination remains underexplored. In the present study, we investigated the impact of a human blood-relevant PFAS mixture, containing perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) on innate (monocytes and NK cells), cell-mediated (T cells) and B cells adaptive immune responses in COVID-19-vaccinated female and male healthy donors. Human peripheral blood mononuclear cells (PBMCs) were exposed to a mixture of the six PFAS at real life concentrations and subsequently stimulated with the SARS-CoV-2 spike peptide. We report a significant upregulation of IFNγ production in T and NK cells, particularly among male donors exposed to high concentrations of the PFAS mixture. Conversely, we observed a decrease in the total B-cell population, particularly among female donors. A significant reduction in the secretion of the pro-inflammatory chemokines MIP-1α (CCL3) and MIP-3α (CCL20) was observed at high PFAS mixture concentrations. Overall, these findings suggest that high PFAS exposure may differentially affect immune responses in a sex-specific manner, with a potential impact on vaccine efficacy.

Selection of the critical effect size alters hazard characterization - a retrospective analysis of key studies used for risk assessments of PFAS

Regulatory values for per- and polyfluoroalkyl substances (PFAS) vary widely across agencies, creating inconsistencies that challenge effective risk management and public health communication. These differences often stem from methodological choices in determining points of departure (PoDs), the selection of critical effect size (CES) and the modeling framework for benchmark dose (BMD) analysis. This study investigates the impact of CES selection on hazard characterization by analyzing how variations in CES influence resulting PoDs and health-based guidance values. A retrospective analysis of key studies from four regulatory PFAS risk assessments was conducted, covering both animal and epidemiological data (thyroid hormone, cholesterol, and vaccine response). CES options compared included 5%, 10%, one standard deviation from background, and a generalized effect size theory, using both frequentist and Bayesian statistics. The findings show that CES selection and statistical approach substantially affect BMD estimates such as the lower bound BMD (BMDL) of the respective confidence interval or credible interval; with larger CES values and Bayesian modeling yielding more biologically relevant, stable results. For instance, Bayesian methods provided narrower credible intervals, compared to frequentist methods at lower CES levels, minimizing overly conservative assessments. However, in comparison to the PoD previously derived by the European Food Safety Authority the results generally suggest lower values. In conclusion, this study supports the use of a flexible, endpoint-specific CES with Bayesian model averaging, which may enhance the accuracy and consistency of PFAS guidance values, offering a more robust foundation for regulatory risk assessments.

Application of a quantitative uncertainty assessment to develop ranges of plausible toxicity values when using observational data in risk assessment: a case study examining associations between PFOA and PFOS exposures and vaccine response

Traditional approaches for quantitatively characterizing uncertainty in risk assessment require adaptation to accommodate increased reliance on observational (vs experimental) studies in developing toxicity values. Herein, a case study with perfluorooctanoic acid (PFOA) and PFOS and vaccine response explores approaches for qualitative and-where possible-quantitative assessments of uncertainty at each step in the toxicity value development process when using observational data, including review and appraisal of individual studies, candidate study selection, dose-response modeling, and application of uncertainty factors. Each of the 15 studies identified had uncertainties due to risk of bias in confounding, outcome, and exposure ascertainment, likely contributing to the observed inconsistencies within and across studies, and resulting in lack of candidacy for dose-response assessment. Nonetheless, 2 representative studies were selected to demonstrate possible methods to quantify uncertainty in the remaining steps. Data simulations indicated lack of a clear dose-response relationship; dose-response models fit to representative simulations indicated high uncertainty in both the magnitude and direction of effect with simulated benchmark dose and its lower limit values varying at least 66- and 86-fold for PFOA and PFOS. Uncertainty factor application added minimal uncertainty. Combined, a high level of uncertainty was observed, precluding the ability to confidently assess causal dose-response relationships with the observational data, alone. This case study highlights the need for quantitative uncertainty analysis when developing toxicity values with observational data and, importantly, emphasizes the need for application of additional techniques to directly assess causality and the specificity of dose-response when relying on studies of association in quantitative risk assessment.

Maternal exposure to legacy PFAS compounds PFOA and PFOS is associated with disrupted cytokine homeostasis in neonates: The Upstate KIDS study (2008-2010)

There is growing concern that exposure to per/polyfluoroalkyl substances (PFAS), persistent chemicals used widely to make consumer products water- or grease-proof, may alter immune function, leading to reduced vaccine response or greater susceptibility to infections. We investigated associations between two legacy PFAS (PFOA and PFOS) and infant cytokine levels measured in newborn dried bloodspots (NDBS) from a large population-based birth cohort in Upstate New York, to determine whether exposure to legacy PFAS is associated with variability in cytokine profiles in newborns. We performed adjusted mixed effects regressions for each cytokine against PFOS and PFOA followed by exploratory factor analysis (EFA) on specific cytokine subsets selected via the prior regressions. Among 3448 neonates (2280 singletons and 1168 twins), significant cytokines were dominated by cytokines negatively associated with the given PFAS. Adjusted single-pollutant models with continuous log-transformed PFOA showed significant negative associations with IL-16 (-0.07, 95% CI: -0.3, -0.1), IL-5 (-0.05, 95%CI: -0.09, -0.02), IL-6 (-0.06, 95%CI: -0.1, -0.02), 6-Ckine (0.06, 95% CI: -0.10, -0.02) and significant positive associations with IL-1α (0.066, 95%CI: 0.03, 0.11), MCP-1 (0.06, 95%CI: 0.03, 0.10). Estimates for PFOS were slightly larger than estimates for PFOA but only significant for 6-Ckine (-0.21, 95%CI: -0.09, -0.33) after correction for multiplicity. Our data consistently suggest that legacy PFAS exposures are associated with disrupted, typically reduced, cytokine levels in neonates, with PFOA exposure resulting in more significant differences in individual cytokines and cytokine groupings than PFOS. Regression by PFAS quartile shows evidence of nonlinear dose-response relationships for most cytokines and cytokine groupings.

Per- and polyfluoroalkyl substances alter innate immune function: evidence and data gaps

Per- and polyfluoroalkyl substances (PFASs) are a large class of compounds used in a variety of processes and consumer products. Their unique chemical properties make them ubiquitous and persistent environmental contaminants while also making them economically viable and socially convenient. To date, several reviews have been published to synthesize information regarding the immunotoxic effects of PFASs on the adaptive immune system. However, these reviews often do not include data on the impact of these compounds on innate immunity. Here, current literature is reviewed to identify and incorporate data regarding the effects of PFASs on innate immunity in humans, experimental models, and wildlife. Known mechanisms by which PFASs modulate innate immune function are also reviewed, including disruption of cell signaling, metabolism, and tissue-level effects. For PFASs where innate immune data are available, results are equivocal, raising additional questions about common mechanisms or pathways of toxicity, but highlighting that the innate immune system within several species can be perturbed by exposure to PFASs. Recommendations are provided for future research to inform hazard identification, risk assessment, and risk management practices for PFASs to protect the immune systems of exposed organisms as well as environmental health.

Associations between per- and poly-fluoroalkyl substance (PFAS) exposure and immune responses among women in the California Teachers study: A cross-sectional evaluation

INTRODUCTION

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that have been linked to a number of health outcomes, including those related to immune dysfunction. However, there are limited numbers of epidemiological-based studies that directly examine the association between PFAS exposure and immune responses.

METHODS

In this cross-sectional study nested in the California Teachers Study cohort, we measured nine PFAS analytes in serum. Of the 9 analytes, we further evaluated four (PFHxS [perfluorohexane sulfonate], PFNA [perfluorononanoic acid], PFOA [perfluorooctanoic acid], PFOS [perfluorooctanesulfonic acid]) that had detection levels of > 80 %, in relation to 16 systemic inflammatory/immune markers and corresponding immune pathways (Th1 [pro-inflammatory/macrophage activation], B-cell activation, and T-cell activation). Study participants (n = 722) were female, completed a questionnaire regarding various health measures and behaviors, and donated a blood sample between 2013-2016. The association between PFAS analytes and individual immune markers and pathways were evaluated by calculating odds ratios (OR) and 95 % confidence intervals (CI) in a logistic regression model. PFAS analytes were evaluated both as a dichotomous exposure (above or below the respective median) and as a continuous variable (per 1 unit increase [ng/mL]).

RESULTS

The prevalence of detecting any PFAS analyte rose with increasing age, with the highest PFAS prevalence observed among those aged 75 + years and the lowest PFAS prevalence observed among those aged 40-49 years (study participant age range: 40-95 years). Significant associations with BAFF (B-cell activating factor) levels above the median were observed among participants with elevated (defined as above the median) levels of PFHxS (OR=1.53), PFOA (OR=1.43), and PFOS (OR=1.40). Similarly, there were statistically significant associations between elevated levels of PFHxS and TNFRII (tumor necrosis factor receptor 2) levels (OR=1.78) and IL2Rα (interleukin 2 receptor subunit alpha) levels (OR=1.48). We also observed significant inverse associations between elevated PFNA and sCD14 (soluble cluster of differentiation 14) (OR=0.73). No significant associations were observed between elevated PFNA and any immune marker. Evaluation of PFAS exposures as continuous exposures in association with dichotomized cytokines were generally consistent with the dichotomized associations.

CONCLUSIONS

PFAS exposure was associated with altered levels of circulating inflammatory/immune markers; the associations were specific to PFAS analyte and immune marker. If validated, our results may suggest potential immune mechanisms underlying associations between the different PFAS analytes and adverse health outcomes.

Advancing PFAS risk assessment: Integrative approaches using agent-based modelling and physiologically-based kinetic for environmental and health safety

Per- and polyfluoroalkyl substances (PFAS), ubiquitous in a myriad of consumer and industrial products, and depending on the doses of exposure represent a hazard to both environmental and public health, owing to their persistent, mobile, and bio accumulative properties. These substances exhibit long half-lives in humans and can induce potential immunotoxic effects at low exposure levels, sparking growing concerns. While the European Food Safety Authority (EFSA) has assessed the risk to human health related to the presence of PFAS in food, in which a reduced antibody response to vaccination in infants was considered as the most critical human health effect, a comprehensive grasp of the molecular mechanisms spearheading PFAS-induced immunotoxicity is yet to be attained. Leveraging modern computational tools, including the Agent-Based Model (ABM) Universal Immune System Simulator (UISS) and Physiologically Based Kinetic (PBK) models, a deeper insight into the complex mechanisms of PFAS was sought. The adapted UISS serves as a vital tool in chemical risk assessments, simulating the host immune system's reactions to diverse stimuli and monitoring biological entities within specific adverse health contexts. In tandem, PBK models unravelling PFAS' biokinetics within the body i.e. absorption, distribution, metabolism, and elimination, facilitating the development of time-concentration profiles from birth to 75 years at varied dosage levels, thereby enhancing UISS-TOX's predictive abilities. The integrated use of these computational frameworks shows promises in leveraging new scientific evidence to support risk assessments of PFAS. This innovative approach not only allowed to bridge existing data gaps but also unveiled complex mechanisms and the identification of unanticipated dynamics, potentially guiding more informed risk assessments, regulatory decisions, and associated risk mitigations measures for the future.

The T cell response to SARS-CoV-2 mRNA vaccine in adults with high exposure to perfluoroalkyl substances from Ronneby, Sweden

BACKGROUND

Perfluoroalkyl substances (PFAS) have been associated with impaired antibody levels after childhood vaccinations and immunosuppressive effects in animals. However, the in vivo effects of PFAS on antigen specific human T cell responses have not been investigated in adults. In Ronneby, Sweden, the drinking water of one of the water works was previously highly contaminated with primarily perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS). The COVID-19 vaccination scheme presented the possibility to assess antigen specific T cell function after vaccination in adults with high PFAS serum levels.

OBJECTIVES

To investigate the relationship between PFAS exposure and T cell responses after COVID-19 vaccination in a population with varied PFAS exposure.

METHODS

116 COVID-19 naïve individuals from Ronneby and a background exposed group were included from the PFAS Immune Response After COVID-19 Vaccination cohort (PIRVACoV). All participants received two doses of Spikevax® (Moderna) vaccine. Blood T cells were stimulated with overlapping peptides based on the SARS-CoV-2 spike protein and their production of the cytokines IFN-γ, IL-2, and TNF were measured. The general immune response was assessed by measurement of phytohemagglutinin stimulated cytokines and total immunoglobulin serum levels. Adjusted mixed linear regressions were fitted against measured, address-based and prenatal PFAS exposure indices.

RESULTS

PFAS median serum levels differed greatly between participants ever having had contaminated drinking water at home (PFOS 47 ng/mL, 5th to 95th percentile 6-221 ng/mL) and the background group (PFOS 4 ng/mL, 2-9 ng/mL). PFAS exposure was not associated with SARS-CoV-2 specific T cell cytokine responses (e.g., measured PFOS to IFN-γ: +3% per interquartile range PFOS, 95% confidence interval: 10, 17), nor general immune response.

CONCLUSIONS

This study indicates, in concordance with the PIRVACoV antibody study and other antibody PFAS/COVID-19 studies, that PFAS exposed, healthy adults mount adequate immune responses to mRNA COVID-19 vaccination. EudraCT-number: 2021-000842-16.

In utero exposure to per - and polyfluoroalkyl substances (PFAS) associates with altered human infant T helper cell development

Background

Environmental exposures to chemical toxicants during gestation and infancy can dysregulate multiple developmental processes, causing lifelong effects. There is compelling evidence of PFAS-associated immunotoxicity in adults and children. However, the effect of developmental PFAS exposure on infant T-cell immunity is unreported, and, if present, could be implicated in immune-related health outcomes.

Objectives

We seek to model longitudinal changes in CD4+ T-cell subpopulations from birth through 12 months and their association with in-utero PFAS exposure and postnatal CD4+ T-cell frequencies and functions.

Methods

Maternal-infant dyads were recruited as part of the UPSIDE-ECHO cohort during the first trimester between 2015 and 2019 in Rochester, New York; dyads were followed through the infant's first birthday. Maternal PFAS concentrations (PFOS, PFOA, PFNA, and PFHXS) were quantified in serum during the second trimester using high-performance liquid chromatography and tandem mass spectrometry. Infant lymphocyte frequencies were assessed at birth, 6- and 12-months using mass cytometry and high-dimensional clustering methods. Linear mixed-effects models were employed to analyze the relationship between maternal PFAS concentrations and CD4+ T-cell subpopulations (n=200). All models included a PFAS and age interaction and were adjusted for parity, infant sex, and pre-pregnancy body mass index.

Results

In-utero PFAS exposure correlated with multiple CD4+ T-cell subpopulations in infants. The greatest effect sizes were seen in T-follicular helper (Tfh) and T-helper 2 (Th2) cells at 12 months. A log 2 -unit increase in PFOS was associated with lower Tfh [0.17% (95%CI: -0.30, -0.40)] and greater Th2 [0.27% (95%CI: 0.18, 0.35)] cell percentages at 12 months. Similar trends were observed for PFOA, PFNA, and PFHXS.

Discussion

Maternal PFAS exposures correlate with cell-specific changes in the infant T-cell compartment, including key CD4+ T-cell subpopulations that play central roles in coordinating well-regulated, protective immunity. Future studies into the role of PFAS-associated T-cell distribution and risk of adverse immune-related health outcomes in children are warranted.

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

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

Exposure to Pollutants and Vaccines' Effectiveness: A Systematic Review

Background: Many human activities release harmful substances, contaminating the air, water, and soil. Since exposure to environmental pollutants is currently unavoidable, it is important to verify how these compounds may influence individual immune responses to vaccines. Methods: This review was conducted in accordance with the PRISMA statement. The protocol was registered on the PROSPERO platform with the following ID: CRD42024582592. We evaluated all observational, semi-experimental, and experimental studies written in both Italian and English that reported possible effects of exposure to environmental pollutants on the production of vaccine-induced antibodies. Results: Forty-two studies were included. The effects of pollutants were examined mainly in terms of antibody production in relation to mumps, measles and rubella, diphtheria and tetanus, hepatitis A and B, Haemophilus influenzae type B, influenza, tuberculosis, pertussis, Japanese encephalitis, poliomyelitis, and COVID-19 vaccines. Perfluorinated compounds were the most studied pollutants. Conclusions: Correlations between exposure to pollutants and reductions in antibody production were found in quite all the selected studies, suggesting that pollution control policies could contribute to increase the efficacy of vaccination campaigns. However, the heterogeneity of the examined studies did not allow us to perform a meta-analysis, and the literature on each type of vaccine or pollutant is still too limited to generate robust evidence. In order to confirm the findings of the present systematic review, and in the perspective of establishing possible exposure limit values for each type of pollutant, further research in this field is required.

Multimedia and Full-Life-Cycle Monitoring Discloses the Dynamic Accumulation Rules of PFAS and Underestimated Foliar Uptake in Wheat near a Fluorochemical Industrial Park

The escalating concern of perfluoroalkyl and polyfluoroalkyl substances (PFAS), particularly at contaminated sites, has prompted extensive investigations. In this study, samples of multimedia including air, rhizosphere soil, and tissues of wheat at various growing stages were collected near a mega fluorochemical industrial park in China. Perfluorooctanoic acid (PFOA) was predominant in both air and soil with a strong correlation, highlighting air deposition as an important source in the terrestrial system. PFAS concentrations in wheat decreased in the stem and ear but increased in the leaves as wheat matured. Specifically, perfluorobutanoic acid (PFBA) dominated in the aboveground tissues in the full-life-cycle, except that PFOA surpassed and became predominant in leaves during the filling and maturing stages, hinting at an airborne source. For all PFAS, both bioaccumulation factors and translocation factors (TFs) were inversely correlated with the carbon chain length during the full-life-cycle. The obtained TF values were considerably higher than those obtained from ambient sites reported previously, further suggesting an unneglectable foliar uptake from air, which was estimated to be 25% for PFOA. Moreover, spray irrigation remarkably enhanced the absorption of PFAS in wheat via foliar uptake relative to flood irrigation. The estimated daily intake of PFBA via wheat consumption and air inhalation was 0.50 μg/kg/day for local residents, at least one magnitude higher than the corresponding threshold, suggesting an alarmingly high exposure risk.

Advances in perfluoro-alkylated compounds (PFAS) detection in seafood and marine environments: A comprehensive review on analytical techniques and global regulations

Per- and poly-fluoroalkyl substances (PFAS) are persistent organic pollutants that severely threaten the environment and human health due to their distinct chemical composition, extensive production, widespread distribution, bioaccumulation in nature, and long-term persistence. This review focuses on the occurrence and sources of PFAS in seafood, with a particular emphasis on advanced detection methods viz. nanoparticle-based, biosensor-based, and metal-organic frameworks-based, and mass spectrometric techniques. The challenges associated with these advanced detection technologies are also discussed. Recent research and regulatory updates about PFAS, including hazardous and potential health effects, epidemiological studies, and various risk assessment models, have been reviewed. In addition, the need for global monitoring programs and regulations on PFAS are critically reviewed by underscoring their crucial role in protecting human health and the environment. Further, approaches for reducing PFAS in seafood are highlighted with future innovative remediation directions. Although advanced PFAS analytical methods are available, selectivity, sample preparation, and sensitivity are still significant challenges associated with detection of PFAS in seafood matrices.  Moreover, crucial research gaps and solutions to essential concerns are critically explored in this review.

Novel pillar[n]arenes magnetic nanoparticles: Preparation and application in quantitative analysis of trace perfluorinated compounds from aqueous samples

BACKGROUND

Perfluorinated compounds (PFCs) are a class of widely manufactured and used emerging persistent pollutants. The recent discovered new class of macrocycles pillararenes have garnered significant attention for the applications in environmental pollutant adsorption, with abundant π electron cavities, a symmetrical rigid structure, and host-guest recognition capabilities.

RESULTS

In this work, we designed and synthesized novel cationic pillar [n]arenes magnetic nanoparticles (CWPA5@MNPs), and investigated its adsorption performance and mechanism as a type of new adsorbent for the enrichment of PFCs. The results indicate that CWPA5@MNPs exhibits selectively strong affinity for perfluorooctane sulfonate (PFOS) and long-chain (C9-C14) perfluorocarboxylic acids (PFCAs), with the adsorption efficiency exceeding 80 % within 12 min. The maximum adsorption capacity of CWPA5@MNPs for PFOS was measured to be 29.02 mg/g. CWPA5@MNPs can be rapidly isolated from the solution using external magnets, offering a quick and easy separation. Consequently, this study established a CWPA5@MNPs-assisted magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography-tandem mass spectrometry (CWPA5@MNPs-MSPE-HPLC-MS/MS) method for the rapid detection of trace levels of PFCs in environmental water samples. The analysis of 7 PFCs yielded recovery rates ranging from 86.1 % to 107.5 %, with intraday and interday relative standard deviations (RSD) of 3.6-6.4 % and 1.3-7.0 %, respectively.

SIGNIFICANCE AND NOVELTY

The study reveals the synthesis and application of novel cationic pillar [n]arenes magnetic nanoparticles (CWPA5@MNPs) as highly efficient adsorbents for selective perfluorinated compounds (PFCs) in water samples. It demonstrates the potential of the newly developed CWPA5@MNPs-MSPE-HPLC-MS/MS method for the quantitative analysis of PFCs in environment, with high sensitivity, accuracy and stability.

Carbon Adsorbent Properties Impact Hydrated Electron Activity and Perfluorocarboxylic Acid (PFCA) Destruction

Carbon-based adsorbents used to remove recalcitrant water contaminants, including perfluoroalkyl substances (PFAS), are often regenerated using energy-intensive treatments that can form harmful byproducts. We explore mechanisms for sorbent regeneration using hydrated electrons (eaq -) from sulfite ultraviolet photolysis (UV/sulfite) in water. We studied the UV/sulfite treatment on three carbon-based sorbents with varying material properties: granular activated carbon (GAC), carbon nanotubes (CNTs), and polyethylenimine-modified lignin (lignin). Reaction rates and defluorination of dissolved and adsorbed model perfluorocarboxylic acids (PFCAs), perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA), were measured. Monochloroacetic acid (MCAA) was employed to empirically quantify eaq - formation rates in heterogeneous suspensions. Results show that dissolved PFCAs react rapidly compared to adsorbed ones. Carbon particles in solution decreased aqueous reaction rates by inducing light attenuation, eaq - scavenging, and sulfite consumption. The magnitude of these effects depended on adsorbent properties and surface chemistry. GAC lowered PFOA destruction due to strong adsorption. CNT and lignin suspensions decreased eaq - formation rates by attenuating light. Lignin showed high eaq - quenching, likely due to its oxygenated functional groups. These results indicate that desorbing PFAS and separating the adsorbent before initiating PFAS degradation reactions will be the best engineering approach for adsorbent regeneration using UV/sulfite.

Immune cell profiles associated with human exposure to perfluorinated compounds (PFAS) suggest changes in natural killer, T helper, and T cytotoxic cell subpopulations

Per- and polyfluoroalkyl substances (PFAS) constitutes a group of highly persistent man-made substances. Recent evidence indicates that PFAS negatively impact the immune system. However, it remains unclear how different PFAS are associated with alterations in circulating leukocyte subpopulations. More detailed knowledge of such potential associations can provide better understanding into mechanisms of PFAS immunotoxicity in humans. In this exploratory study, associations of serum levels of common PFAS (perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS)) and immune cell profiles of peripheral blood mononuclear cells, both with and without immunostimulation, were investigated. High-dimensional single cell analysis by mass cytometry was done on blood leukocytes from fifty participants in the Norwegian human biomonitoring EuroMix study. Different PFAS were associated with changes in various subpopulations of natural killer (NK), T helper (Th), and cytotoxic T (Tc) cells. Broadly, PFAS concentrations were related to increased frequencies of NK cells and activated subpopulations of NK cells. Additionally, increased levels of activated T helper memory cell subpopulations point to Th2/Th17 and Treg-like skewed profiles. Finally, PFAS concentrations were associated with decreased frequencies of T cytotoxic cell subpopulations with CXCR3+ effector memory (EM) phenotypes. Several of these observations point to biologically plausible mechanisms that may contribute to explaining the epidemiological reports of immunosuppression by PFAS. Our results suggest that PFAS exposures even at relatively low levels are associated with changes in immune cell subpopulations, a finding which should be explored more thoroughly in a larger cohort. Additionally, causal relationships should be confirmed in experimental studies. Overall, this study demonstrates the strength of profiling by mass cytometry in revealing detailed changes in immune cells at a single cell level.

Perfluoroalkyl substances and immunotoxicity: An in vitro structure-activity relationship study in THP-1-derived monocytes and macrophages

Recently, PFASs toxicity for the human immune system has become a growing concern. However, there is currently limited information on PFASs immunotoxicity beyond PFHxS, PFOA, PFOS, and PFNA. Therefore, it is urgent to close the present knowledge gap by testing a wider range of compounds. In the present study, twelve compounds were tested for a relationship between the chain-length and headgroup of a PFAS and its cytotoxic for THP-1. As such, THP-1, either as monocytes or differentiated macrophages, were exposed to PFASs in a concentration range of 0-800 μM for either 3 or 24 h. After that, cell viability and reactive oxygen species (ROS) generation were assessed using MTT and DCFH assay, respectively. PFASs' cytotoxicity is dependent on both their chain-length and headgroups. Cell viability decreased with increasing chain-length, and FTOHs displayed markedly higher toxicity than PFCAs and PFSAs. PFASs were ranked based on their calculated Relative Potency Factor. The ranking for the cytotoxicity data on monocytes appears to be 6:2 FTOH ≫ PFNA > PFDA > PFOS > PFOA >4: 2 FTOH > PFHxS = PFHxA > PFBA. For macrophages, this ranking was as follows: 6:2 FTOH >4:2 FTOH > PFOS > PFDA > PFNA > PFOA > PFHxS. The results observed for the ROS generating potential differed as FTOHs generated no ROS. Here, the ranking in monocytes was PFOA > PFNA > PFOS > PFHxS > PFDA > PFHxA = PFBS = PFBA. The ranking for macrophages was PFNA > PFDA ≥ PFOA > PFOS > PFHxA > PFHxS > PFBA = PFBS. In conclusion, the carbon chain-length and functional headgroup of a PFAS are major determinants for their toxicity to THP-1 cells. Furthermore, our study demonstrates the most potent cytotoxic effect for FTOHs in vitro, which has not been observed before to the authors' knowledge.

Identifying the plasma metabolome responsible for mediating immune cell action in severe COVID-19: a Mendelian randomization investigation

Introduction

The immune response regulates the severity of COVID-19 (sCOVID-19). This study examined the cause-and-effect relationship between immune cell traits (ICTs) and the risk of severe COVID-19. Additionally, we discovered the potential role of plasma metabolome in modulating this risk.

Methods

Employing data from a genome-wide association study (GWAS), we conducted a two-sample Mendelian randomization (MR) assessment of 731 genetic ICTs and sCOVID-19 (5,101 cases, 1,383,241 controls) incidence. The MR analysis was utilized to further quantitate the degree of plasma metabolome-mediated regulation of immune traits in sCOVID-19.

Results

The inverse variance weighted method recognized 2 plasma metabolites (PMs) responsible for casual associations between immune cells and sCOVID-19 risk. These included Tridecenedioate (C13:1-DC) which regulated the association between CD27 on IgD- CD38br (OR 0.804, 95% CI 0.699-0.925, p = 0.002) and sCOVID-19 risk (mediated proportion: 18.7%); arginine to citrulline ratio which controlled the relationship of CD39 on monocyte (OR 1.053, 95% CI 1.013-1.094, p = 0.009) with sCOVID-19 risk (mediated proportion: -7.11%). No strong evidence that genetically predicted sCOVID-19 influenced the aforementioned immune traits.

Conclusion

In this study, we have successfully identified a cause-and-effect relationship between certain ICTs, PMs, and the likelihood of contracting severe COVID-19. Our findings can potentially improve the accuracy of COVID-19 prognostic evaluation and provide valuable insights into the underlying mechanisms of the disease.

A sensitive method for the determination of per- and polyfluoroalkyl substances in food and food contact material using high-performance liquid chromatography coupled with tandem mass spectrometry

Dietary intake is the major pathway of human exposure to per- and polyfluoroalkyl substances (PFAS). Due to their generally very low concentrations in food, especially for foods of plant origin, and their toxicological relevance, demand is growing for improved selective and sensitive analytical methods for the determination of PFAS in the lower ng/kg range. The relevance is pointed out due to the fact that the European Commission has published limits of quantification (LOQs) in the lower ng/kg range for different food matrices in Recommendation (EU) 2022/1431 on the monitoring of perfluoroalkyl substances in food. For example, LOQs of 2 ng/kg for perfluorooctanesulfonic acid (PFOS), 1 ng/kg for perfluorooctanoic acid (PFOA), 1 ng/kg for perfluorononanoic acid (PFNA) and 4 ng/kg for perfluorohexanesulfonic acid (PFHxS) in fruit, vegetables and baby foods are required. A new, very sensitive method is presented here for the determination of 22 PFAS in food and food contact materials. The method is based on liquid-solid extraction and automated clean-up using two solid phase extraction techniques. The analytes are separated and detected by HPLC-MS/MS. A limit of detection (LOD) of 0.33 ng/kg and an LOQ of 1.0 ng/kg are attained for plant foods such as fruits and vegetables as well as for milk and baby food. For foods of animal origin such as egg, meat, fish and paper-based food contact materials an LOD of 1.6 ng/kg as well as an LOQ of 5.0 ng/kg are attained. PFOS and PFOA were the most abundant compounds in the food samples with concentration as high as 1,051 ng/kg of PFOA in sea weed samples and 772 ng/kg of PFOS in eggs samples. In food contact material samples, higher levels were found with a maximum of 310,000 ng/kg PFHxA. In sum the presented method firstly allows determination of PFAS in a wide variety of foodstuffs and paper-based food contact materials at EU-required concentration ranges.

Childhood PFAS exposure and immunotoxicity: a systematic review and meta-analysis of human studies

BACKGROUND

Exposure to poly- and perfluoroalkyl substances (PFAS) may affect infant and childhood health through immunosuppression. However, the findings of epidemiological literature examining relationships between prenatal/childhood PFAS exposure and vaccine response and infection in humans are still inconclusive. The aim of this review was to examine the effects of PFAS exposure on vaccine antibody response and infection in humans.

METHODS

The MEDLINE/Pubmed database was searched for publications until 1 February 2023 to identify human studies on PFAS exposure and human health. Eligible for inclusion studies had to have an epidemiological study design and must have performed logistic regression analyses of gestational or childhood exposure to PFAS against either antibody levels for pediatric vaccines or the occurrence of children's infectious diseases. Information on baseline exposure to PFAS (in ng/mL), the age of PFAS exposure (gestational or in years), and the outcome was measured, potentially leading to multiple exposure-outcome comparisons within each study was collected. Percentage change and standard errors of antibody titers and occurrence of infectious diseases per doubling of PFAS exposure were calculated, and a quality assessment of each study was performed.

RESULTS

Seventeen articles were identified matching the inclusion criteria and were included in the meta-analysis. In general, a small decrease in antibody response and some associations between PFAS exposure and childhood infections were observed.

CONCLUSIONS

This meta-analysis summarizes the findings of PFAS effects on infant and childhood immune health. The immunosuppression findings for infections yielded suggestive evidence related to PFAS exposure, particularly PFOS, PFOA, PFHxS, and PFNA but moderate to no evidence regarding antibody titer reduction.

SYSTEMATIC REVIEW REGISTRATION

The research protocol of this systematic review is registered and accessible at the Open Science Framework ( https://doi.org/10.17605/OSF.IO/5M2VU ).

EFSA Scientific Committee, More S, Bampidis V, Benford D, Bragard C, Hernandez‐Jerez A, Bennekou SH, Koutsoumanis K, Lambré C, Machera K, Mennes W, Mullins E, Nielsen SS, Schlatter J, Schrenk D, Turck D, Younes M, Fletcher T, Greiner M, Ntzani E, Pearce N, Vinceti M, Vrijheid M, Georgiadis M, Gervelmeyer A, Halldorsson TI. Scientific Committee guidance on appraising and integrating evidence from epidemiological studies for use in EFSA's scientific assessments

EFSA requested its Scientific Committee to prepare a guidance document on appraising and integrating evidence from epidemiological studies for use in EFSA's scientific assessments. The guidance document provides an introduction to epidemiological studies and illustrates the typical biases, which may be present in different epidemiological study designs. It then describes key epidemiological concepts relevant for evidence appraisal. This includes brief explanations for measures of association, exposure assessment, statistical inference, systematic error and effect modification. The guidance then describes the concept of external validity and the principles of appraising epidemiological studies. The customisation of the study appraisal process is explained including tailoring of tools for assessing the risk of bias (RoB). Several examples of appraising experimental and observational studies using a RoB tool are annexed to the document to illustrate the application of the approach. The latter part of this guidance focuses on different steps of evidence integration, first within and then across different streams of evidence. With respect to risk characterisation, the guidance considers how evidence from human epidemiological studies can be used in dose-response modelling with several different options being presented. Finally, the guidance addresses the application of uncertainty factors in risk characterisation when using evidence from human epidemiological studies.

Species Difference? Bovine, Trout, and Human Plasma Protein Binding of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) strongly bind to proteins and lipids in blood, which govern their accumulation and distribution in organisms. Understanding the plasma binding mechanism and species differences will facilitate the quantitative in vitro-to-in vivo extrapolation and improve risk assessment of PFAS. We studied the binding mechanism of 16 PFAS to bovine serum albumin (BSA), trout, and human plasma using solid-phase microextraction. Binding of anionic PFAS to BSA and human plasma was found to be highly concentration-dependent, while trout plasma binding was linear for the majority of the tested PFAS. At a molar ratio of PFAS to protein ν < 0.1 molPFAS/molprotein, the specific protein binding of anionic PFAS dominated their human plasma binding. This would be the scenario for physiological conditions (ν < 0.01), whereas in in vitro assays, PFAS are often dosed in excess (ν > 1) and nonspecific binding becomes dominant. BSA was shown to serve as a good surrogate for human plasma. As trout plasma contains more lipids, the nonspecific binding to lipids affected the affinities of PFAS for trout plasma. Mass balance models that are parameterized with the protein-water and lipid-water partitioning constants (chemical characteristics), as well as the protein and lipid contents of the plasma (species characteristics), were successfully used to predict the binding to human and trout plasma.

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence

PURPOSE OF REVIEW

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies.

RECENT FINDINGS

We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

Dermal bioavailability of perfluoroalkyl substances using in vitro 3D human skin equivalent models

Perfluoroalkyl substances (PFAS) have been identified in various products that come in contact with human skin, ranging from school uniforms to personal care products. Despite this, knowledge on human dermal uptake of PFAS is lacking. Thus, the human dermal absorption of 17 PFAS was assessed, for the first time, using in vitro 3D-human skin equivalent models exposed to 500 ng/cm2 PFAS dissolved in methanol over 24-36 h. The distribution of target PFAS is presented, based on three fractions: absorbed, un-absorbed, and retained within skin tissue (absorbable dose). Perfluoropentanoic acid (PFPeA) and perfluorobutane sulfonate (PFBS) had the highest absorbed fraction, 58.9 % and 48.7 % respectively, with the absorbed fraction decreasing with increasing carbon chain length of the studied perfluorocarboxylic acids (PFCAs) (r = 0.97, p = 0.001) and perfluorosulfonic acids (PFSAs) (r = 0.97, p = 0.004). Interestingly, while longer chain PFAS (Cn ≥ 9) were not directly absorbed, a large fraction of the exposure dose was detected within the skin tissue at the end of the exposure. This was most apparent for perfluoroundecanoic acid (PFUnDA) and perfluorononane sulfonate (PFNS) for which 66.5 % and 68.3 % of the exposure dose was found within the skin tissue, while neither compound was detected in the absorbed fraction. For compounds with a carbon chain length > 11, the fraction found within the skin tissue, decreases with increasing chain length. Physicochemical properties played a role in dermal permeation of PFAS, with a clear inverse correlation between logKOW and absorbed fraction for both PFCAs (r = -0.97; p ≤ 0.001) and PFSAs (r = -0.99; p ≤ 0.001). Steady-state flux (JSS) and permeation coefficients (Papp) were determined for target compounds with significant permeation after 36 h exposure (C5-C8 PFCAs and C4-C7 PFSAs). In general, both the flux and permeation coefficient decreased with increasing chain length.

Associations of per- and polyfluoroalkyl substances (PFAS) and their mixture with risk of rheumatoid arthritis in the U.S. adult population

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are known environmental contaminants with immunosuppressive properties. Their connection to rheumatoid arthritis (RA), a condition influenced by the immune system, is not well studied. This research explores the association between PFAS exposure and RA prevalence.

METHODS

This research utilized data from the NHANES, encompassing a sample of 10,496 adults from the 2003-2018 cycles, focusing on serum levels of several PFAS. The presence of RA was determined based on self-reports. This study used multivariable logistic regression to assess the relationship between individual PFAS and RA risk, adjusting for covariates to calculate odds ratios (ORs). The combined effects of PFAS mixtures were evaluated using BKMR, WQS regression, and quantile g-computation. Additionally, sex-specific associations were explored through stratified analysis.

RESULTS

Higher serum PFOA (OR = 0.88, 95% CI: 0.79, 0.98), PFHxS (OR = 0.91, 95% CI: 0.83, 1.00), PFNA (OR = 0.87, 95% CI: 0.77, 0.98), and PFDA (OR = 0.89, 95% CI: 0.81, 0.99) concentration was related to lower odds of RA. Sex-specific analysis in single chemical models indicated the significant inverse associations were only evident in females. BKMR did not show an obvious pattern of RA estimates across PFAS mixture. The outcomes of sex-stratified quantile g-computation demonstrated that an increase in PFAS mixture was associated with a decreased odds of RA in females (OR: 0.76, 95% CI: 0.62, 0.92). We identified a significant interaction term of the WQS*sex in the 100 repeated hold out WQS analysis. Notably, a higher concentration of the PFAS mixture was significantly associated with reduced odds of RA in females (mean OR = 0.93, 95% CI: 0.88, 0.98).

CONCLUSIONS

This study indicates potential sex-specific associations of exposure to various individual PFAS and their mixtures with RA. Notably, the observed inverse relationships were statistically significant in females but not in males. These findings contribute to the growing body of evidence indicating that PFAS may have immunosuppressive effects.

Inconsistencies in the EU regulatory risk assessment of PFAS call for readjustment

Recognition of per- and polyfluoroalkyl substances (PFAS) as widespread environmental pollutants and a consequent risk to human health, has recently made the European Union (EU) adopt several regulatory measures for their management. The coherence of these measures is challenged by the diversity and the ubiquitous occurrence of PFAS, which also complicates the EU's endeavor to advance justified, harmonized, and transparent approaches in the regulatory assessment of chemical risks. Our study critically reviews the European approach for the risk assessment of PFAS, by applying a comparative analysis of the current and pending regulatory thresholds issued for these chemicals in water bodies, drinking water, and certain foodstuffs. Our study shows that the level of health protection embedded in the studied thresholds may differ by three orders of magnitude, even in similar exposure settings. This is likely to confuse the common understanding of the toxicity and health risks of PFAS and undermine reasonable decision-making and the equal treatment of different stakeholders. We also indicate that currently, no consensus exists on the appropriate level of required health protection regarding PFAS and that the recently adopted tolerable intake value in the EU is too cautious. Based on our analysis, we propose some simple solutions on how the studied regulations and their implicit PFAS thresholds or their application could be improved. We further conclude that instead of setting EU-wide PFAS thresholds for all the environmental compartments, providing the member states with the flexibility to consider case-specific factors, such as regional background concentrations or food consumption rates, in their national regulatory procedures would likely result in more sustainable management of environmental PFAS without compromising the scientific foundation of risk assessment, the legitimacy of the EU policy framework and public health.

Early life poly- and perfluoroalkyl substance levels and adiposity in the first 2 years of life

IMPORTANCE

Poly- and perfluoroalkyl substances (PFASs) are nondegradable, man-made chemicals. They accumulate in humans with potential harmful effects, especially in susceptible periods of human development, such as the first months of life. We found that, in our cohort, exclusively breastfed (EBF) infants had 3 times higher PFAS plasma levels compared with exclusively formula-fed (EFF) infants at the age of 3 months. Thus, PFASs could potentially reduce the health benefits of breastfeeding.

OBJECTIVE

We investigated the associations between PFAS levels at the age of 3 months and accelerated gain in fat mass during the first 6 months of life, body composition at 2 years, and whether these associations differ between EBF and EFF infants.

SETTING

In 372 healthy term-born infants, we longitudinally assessed anthropometrics, body composition (by air-displacement plethysmography and dual-energy X-ray absorptiometry), and visceral and subcutaneous fat (by abdominal ultrasound) until the age of 2 years.

MEASURES

The plasma levels of 5 individual PFASs were determined by liquid chromatography-electrospray ionization-tandem mass spectrometry at the age of 3 months.

MAIN OUTCOMES

We studied associations between PFAS levels and outcomes using multiple regression analyses.

RESULTS

Higher early life plasma perfluorooctanoic acid and total PFAS levels were associated with an accelerated gain in fat mass percentage [FM%; >0.67 SD score (SDS)] during the first 6 months of life. Higher early life PFAS levels were associated with lower fat-free mass (FFM) SDS at the age of 2 years, but not with total FM% SDS at 2 years. Furthermore, we found opposite effects of PFAS levels (negative) and exclusive breastfeeding (positive) at the age of 3 months on FFM SDS at 2 years.

CONCLUSION

Higher PFAS levels in early life are associated with accelerated gains in FM% during the first 6 months of life and with lower FFM SDS at the age of 2 years, which have been associated with an unfavorable body composition and metabolic profile later in life. Our findings warrant further research with longer follow-up times.

Determination of in vitro immunotoxic potencies of a series of perfluoralkylsubstances (PFASs) in human Namalwa B lymphocyte and human Jurkat T lymphocyte cells

Exposure to PFASs is associated to several adverse health effects, such as immunotoxicity. Immunotoxic effects of PFOA and PFOS, including a reduced antibody response in both experimental animals and humans, have been reported. However, there is limited understanding of the underlying mechanisms involved. Moreover, there is only a restricted amount of immunotoxicity data available for a limited number of PFASs. In the current study the effects of 15 PFASs, including short- and long-chain perfluorinated carboxylic and sulfonic acids, fluorotelomer alcohols, and perfluoralkyl ether carboxylic acids were studied on the expression of recombinant activating gene 1 (RAG1) and RAG2 in the Namalwa human B lymphoma cell line, and on the human IL-2 promotor activity in Jurkat T-cells. Concentration-response data were subsequently used to derive in vitro relative potencies through benchmark dose analysis. In vitro relative potency factors (RPFs) were obtained for 6 and 9 PFASs based on their effect on RAG1 and RAG2 gene expression in Namalwa B-cells, respectively, and for 10 PFASs based on their inhibitory effect on IL-2 promotor activity in Jurkat T-cells. The most potent substances were HFPO-TA for the reduction of RAG1 and RAG2 gene expression in Namalwa cells (RPFs of 2.1 and 2.3 respectively), and PFDA on IL-2 promoter activity (RPF of 9.1). RAG1 and RAG2 play a crucial role in V (D)J gene recombination, a process for acquiring a varied array of antibodies crucial for antigen recognition. Hence, the effects observed in Namalwa cells might indicate a PFAS-induced impairment of generating a diverse range of B-cells essential for antigen recognition. The observed outcomes in the Jurkat T-cells suggest a possible PFAS-induced reduction of T-cell activation, which may contribute to a decline in the T-cell dependent antibody response. Altogether, the present study provides potential mechanistic insights into the reported PFAS-induced decreased antibody response. Additionally, the presented in vitro models may represent useful tools for assessing the immunotoxic potential of PFASs and prioritization for further risk assessment.

Early-life exposure to perfluoroalkyl substances and serum antibody concentrations towards common childhood vaccines in 18-month-old children in the Odense Child Cohort

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with reduced antibody response to childhood vaccinations. Previous studies have mostly focused on antibodies against diphtheria or tetanus, while fewer studies have assessed antibodies toward attenuated viruses, such as measles, mumps or rubella (MMR). Therefore, we set out to determine associations between prenatal and early postnatal PFAS exposure and vaccine-specific Immunoglobulin G (IgG) in the background-exposed Odense Child Cohort. Blood samples were drawn in pregnancy at gestation weeks 8-16 and from the offspring at age 18 months. In the maternal serum samples we quantified perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA). In the offspring serum samples we quantified the same five PFAS compounds and IgG towards diphtheria, tetanus and MMR. A total of 880 and 841 children were included in the analyses of diphtheria and tetanus or MMR, respectively. Multiple linear regression models were used for estimation of difference in virus-specific IgG per doubling of PFAS concentrations. Maternal PFAS concentrations were non-significantly inversely associated with most vaccine-specific antibody concentrations. Likewise, child PFAS concentrations were associated with non-significant reductions of antibodies towards tetanus and MMR. A significant reduction in the percent difference in mumps antibody concentration per doubling of child PFNA (-9.2% (95% confidence interval: -17.4;-0.2)), PFHxS (-8.3% (-15.0;-1.0) and PFOS (-7.9% (-14.8;-0.4) was found. These findings are of public health concern, as inadequate response towards childhood vaccines may represent a more general immune dysfunction.

Luminescence Lifetime-Based Sensing Platform Based on Cyclometalated Iridium(III) Complexes for the Detection of Perfluorooctanoic Acid in Aqueous Samples

Luminescence lifetimes are an attractive analytical method for detection due to its high sensitivity and stability. Iridium probes exhibit luminescence with long excited-state lifetimes, which are sensitive to the local environment. Perfluorooctanoic acid (PFOA) is listed as a chemical of high concern regarding its toxicity and is classified as a "forever chemical". In addition to strict limits on the presence of PFOA in drinking water, environmental contamination from industrial effluent or chemical spills requires rapid, simple, accurate, and cost-effective analysis in order to aid containment. Herein, we report the fabrication and function of a novel and facile luminescence sensor for PFOA based on iridium modified on gold surfaces. These surfaces were modified with lipophilic iridium complexes bearing alkyl chains, namely, IrC6 and IrC12, and Zonyl-FSA surfactant. Upon addition of PFOA, the modified surfaces IrC6-FSA@Au and IrC12-FSA @Au show the largest change in the red luminescence signal with changes in the luminescence lifetime that allow monitoring of PFOA concentrations in aqueous solutions. The platform was tested for the measurement of PFOA in aqueous samples spiked with known concentrations of PFOA and demonstrated the capacity to determine PFOA at concentrations >100 μg/L (240 nM).

Altered Transcriptome Response in PBMCs of Czech Adults Linked to Multiple PFAS Exposure: B Cell Development as a Target of PFAS Immunotoxicity

While the immunomodulation effects of per- and polyfluoroalkyl substances (PFASs) are described on the level of clinical signs in epidemiological studies (e.g., suppressed antibody response after vaccination), the underlying mechanism has still not been fully elucidated. To reveal mechanisms of PFAS exposure on immunity, we investigated the genome-wide transcriptomic changes of peripheral blood mononuclear cells (PBMCs) responding to PFAS exposure (specifically, exposure to PFPA, PFOA, PFNA, PFDA, PFUnDA, PFHxS, and PFOS). Blood samples and the chemical load in the blood were analyzed under the cross-sectional CELSPAC: Young Adults study. The overall aim of the study was to identify sensitive gene sets and cellular pathways conserved for multiple PFAS chemicals. Transcriptome networks related to adaptive immunity were perturbed by multiple PFAS exposure (i.e., blood levels of at least four PFASs). Specifically, processes tightly connected with late B cell development, such as B cell receptor signaling, germinal center reactions, and plasma cell development, were shown to be affected. Our comprehensive transcriptome analysis identified the disruption of B cell development, specifically the impact on the maturation of antibody-secreting cells, as a potential mechanism underlying PFAS immunotoxicity.

Re-expressing coefficients from regression models for inclusion in a meta-analysis

Meta-analysis poses a challenge when original study results have been expressed in a non-uniform manner, such as when regression results from some original studies were based on a log-transformed key independent variable while in others no transformation was used. Methods of re-expressing regression coefficients to generate comparable results across studies regardless of data transformation have recently been developed. We examined the relative bias of three re-expression methods using simulations and 15 real data examples where the independent variable had a skewed distribution. Regression coefficients from models with log-transformed independent variables were re-expressed as though they were based on an untransformed variable. We compared the re-expressed coefficients to those from a model fit to the untransformed variable. In the simulated and real data, all three re-expression methods usually gave biased results, and the skewness of the independent variable predicted the amount of bias. How best to synthesize the results of the log-transformed and absolute exposure evidence streams remains an open question and may depend on the scientific discipline, scale of the outcome, and other considerations.

Per- and poly-fluoroalkyl substances in commercial organic eggs via fishmeal in feed

Chicken eggs can be a significant source of human PFAS exposure. A survey of PFAS in commercial eggs from larger farms across Denmark showed the absence or low contents of PFAS in free-range and barn eggs. However, organic eggs from eight farms collected in September 2022 had a similar profile of nine PFASs with a predominance of odd over even carbon length PFCAs. Farm 11-13 e.g. had egg yolk ng/g concentrations of PFOA 0.07 ± 0.02; PFNA 0.37 ± 0.04; PFDA 0.13 ± 0.00; PFUnDA 0.22 ± 0.04; PFDoDA 0.06 ± 0.02; PFTrDA 0.15 ± 0.04; PFTeDA 0.02 ± 0.02; PFHxS 0.10 ± 0.04; PFOS 2.62 ± 0.11. Normalised to PFOS, the relative sum of other PFAS showed no difference between the eight organic egg samples, but significant differences between mean individual PFASs (p = 1.4E-25), reflecting a similar profile. The PFAS found in two fishmeal samples with the same origin as the fishmeal used for the organic feed production, could account for the contents in the eggs via estimated transfer from the feed. Furthermore, the estimated transfer from concentration in feed to concentration in egg increased with the carbon length of the PFCA. Exposure (95th percentile) of ∑4PFAS (PFOA, PFNA, PFHxS, PFOS) solely from consumption of 311 g ∼ 5-6 organic eggs/week was for children 4-9 years 10.4 ng/kg bw, i.e. a significant exceedance of the tolerable weekly intake of 4.4 ng/kg bw established by the European Food Safety Authority. Based on the PFAS exposures from organic egg consumption, the organic egg producers decided voluntarily to cease adding fishmeal to the feed. Since the feed-to-egg half-lives are ≤1 week for PFOA, PFOS, and PFHxS, the removal of fishmeal as a feed ingredient should eliminate PFAS after 1-2 months. This was demonstrated in analyses of ten organic egg samples collected by the authorities without PFAS in eight and with 0.1 and 0.4 ng/g ∑4PFAS in two samples.

Range of the perfluorooctanoate (PFOA) safe dose for human health: An international collaboration

Many government agencies and expert groups have estimated a dose-rate of perfluorooctanoate (PFOA) that would protect human health. Most of these evaluations are based on the same studies (whether of humans, laboratory animals, or both), and all note various uncertainties in our existing knowledge. Nonetheless, the values of these various, estimated, safe-doses vary widely, with some being more than 100,000 fold different. This sort of discrepancy invites scrutiny and explanation. Otherwise what is the lay public to make of this disparity? The Steering Committee of the Alliance for Risk Assessment (2022) called for scientists interested in attempting to understand and narrow these disparities. An advisory committee of nine scientists from four countries was selected from nominations received, and a subsequent invitation to scientists internationally led to the formation of three technical teams (for a total of 24 scientists from 8 countries). The teams reviewed relevant information and independently developed ranges for estimated PFOA safe doses. All three teams determined that the available epidemiologic information could not form a reliable basis for a PFOA safe dose-assessment in the absence of mechanistic data that are relevant for humans at serum concentrations seen in the general population. Based instead on dose-response data from five studies of PFOA-exposed laboratory animals, we estimated that PFOA dose-rates 10-70 ng/kg-day are protective of human health.

Prenatal Exposure to Poly- and Perfluoroalkyl Substances (2009-2014) and Vaccine Antibody Titers of Measles, Mumps, Rubella, and Varicella in Children Four to Eight Years Old from the Healthy Start Cohort

BACKGROUND

Prenatal exposures to certain poly- and perfluoroalkyl substances (PFAS) are associated with reduced humoral responses to some childhood immunizations.

OBJECTIVE

We estimated associations between prenatal PFAS exposure and child antibody titers for measles, mumps, rubella (MMR), and varicella after immunization.

METHODS

We measured serum antibody titers of 145 children (4-8 y old) enrolled in the Healthy Start cohort in Colorado, whose mothers had PFAS quantified mid-pregnancy (2009-2014). We used linear and logistic regression models to assess the relationship between five PFAS detected in > 65 % of mothers and continuous or non-high-censored ("low") antibody titers and quantile g-computation to evaluate the overall effect of the PFAS mixture.

RESULTS

Median concentrations of individual PFAS were at or below the median reported among females in the United States. After receiving two vaccine doses, seropositive levels of antibodies were detected among most (93%-100%) children. Each log-unit increase in perfluorononanoate was associated with 2.09 [95% confidence interval (CI): 1.13, 3.87] times higher odds of a low measles titer, and each log-unit increase in perfluorooctanoate was associated with 2.46 (95% CI: 1.28, 4.75) times higher odds of a low mumps titer. Odds ratios for all other PFAS were elevated, but CIs included the null. Each quartile increase in the PFAS mixture was associated with 1.35 (95% CI: 0.80, 2.26) times higher odds of a low measles titer and 1.44 (95% CI: 0.78, 2.64) times higher odds of a low mumps titer. No significant associations were observed between PFAS and varicella or rubella antibodies. In stratified analyses, associations were negative among female children, except for perfluorohexane sulfonate and varicella, whereas they were positive among males.

DISCUSSION

Some prenatal PFAS were associated with lower antibody titers among fully immunized children. The potential for immunotoxic effects of PFAS requires further investigation in a larger study, because exposure is ubiquitous globally. https://doi.org/10.1289/EHP12863.

Dermal bioaccessibility of perfluoroalkyl substances from household dust; influence of topically applied cosmetics

PFAS are known contaminants of indoor dust. Despite the adherence of such dust to skin, the dermal penetration potential of PFAS is not well understood. By applying in vitro physiologically based extraction tests, the bioaccessibility of 17 PFAS from indoor dust to synthetic human sweat sebum mixtures (SSSM) was assessed. The composition of the SSSM substantially impacted the bioaccessibility of all target compounds. PFAS bioaccessibility in a 1:1 sweat:sebum mixture ranged from 54 to 92% for perfluorocarboxylic acids (PFCAs) and 61-77% for perfluorosulfonic acids (PFSAs). Commonly applied cosmetics (foundation, sunscreen, moisturiser, and deodorant) significantly impacted the dermal bioaccessibility of target PFAS, e.g., the presence of moisturiser significantly decreased the total bioaccessibility of both PFCAs and PFSAs. Preliminary human exposure estimates revealed dermal contact with indoor dust could contribute as much as pathways such as drinking water and dust ingestion to an adult's daily intake of PFAS. While further research is needed to assess the percutaneous penetration of PFAS in humans, the current study highlights the potential substantial contribution of dermal exposure to human body burdens of PFAS and the need for further consideration of this pathway in PFAS risk assessment studies.

Worldwide serum concentration-based probabilistic mixture risk assessment of perfluoroalkyl substances among pregnant women, infants, and children

Pregnant women, infants, and children are particularly vulnerable to perfluoroalkyl substances (PFASs), yet little is known about related health risks. Here, we aimed to study the four main PFASs: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS), and assess the mixture risks of co-exposure to PFASs for pregnant women and children as well as for infants associated with maternal PFAS exposure at national and global scales, based on biomonitoring data on serum. We conducted a literature search and aggregated 69 data sources across 22 countries/regions from 2010 to 2020 to profile the serum concentrations of these four PFASs in pregnant women and children. Based on toxicity assessments by regulatory authorities, we determined conservative reference levels (RfLs) in the serum for the primary adverse effects of PFASs, including hepatic, developmental, and immune effects. The cumulative hazard quotient (HQ) was combined with probabilistic analysis to compare serum levels with RfLs and to quantify mixture risks. Our analysis revealed that PFOS was the dominant PFAS in maternal and child serum worldwide, with median levels 2.5-10 times higher than those of PFOA, PFNA, and PFHxS. The estimated global median serum levels of PFOS were 6.17 ng/mL for pregnant women and 4.85 ng/mL for children, and their immune effects in pregnant women and children are concerning as their cumulative HQs could exceed 1. For infants, the cumulative HQs for both developmental and immune effects could also be > 1, suggesting that maternal exposure to PFASs during pregnancy and breastfeeding may pose concerns for infant development and immunity. Our national and global serum database and risk assessment offer additional insights into PFAS exposures and mixture risks in susceptible populations, serving as a reference for evaluating the effectiveness of ongoing regulatory mitigation measures.