Perfluoroalkyl compounds in dust from Asian, Australian, European, and North American homes and UK cars, classrooms, and offices

Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust - Effect of temperature and ventilation

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18-16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6-40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus)

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 μg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.

Associations of perfluoroalkyl substances with metabolic-associated fatty liver disease and non-alcoholic fatty liver disease: NHANES 2017-2018

OBJECTIVES

This study investigated the potential effects of perfluoroalkyl substance (PFAS) in serum on MAFLD, NAFLD, and liver fibrosis.

METHODS

Our sample included 696 participants (≥ 18 years) from the 2017-2018 NHANES study with available serum PFASs, covariates, and outcomes. Using the first quartile of PFAS as the reference group, we used weighted binary logistic regression and multiple ordered logistic regression used to analyze the relationship between PFAS and MAFLD, NAFLD, and liver fibrosis and multiple ordinal logistic regression to investigate the relationship between PFAS and MAFLD, NAFLD, and liver fibrosis and calculated the odds ratio (OR) and 95% confidence interval for each chemical. Finally, stratified analysis and sensitivity analysis were performed according to gender, age, BMI, and serum cotinine concentration.

RESULTS

A total of 696 study subjects were included, including 212 NAFLD patients (weighted 27.03%) and 253 MAFLD patients (weighted 32.65%). The quartile 2 of serum PFOA was positively correlated with MAFLD and NAFLD (MAFLD, OR 2.29, 95% CI 1.05-4.98; NAFLD, OR 2.37, 95% CI 1.03-5.47). PFAS were not significantly associated with liver fibrosis after adjusting for potential confounders in MAFLD and NAFLD. Stratified analysis showed that PFOA was strongly associated with MAFLD, NAFLD, and liver fibrosis in males and obese subjects. In women over 60 years old, PFHxS was also correlated with MAFLD, NAFLD, and liver fibrosis.

CONCLUSION

The serum PFOA was positively associated with MAFLD and NAFLD in US adults. After stratified analysis, the serum PFHxS was correlated with MFALD, NAFLD, and liver fibrosis.

Southeast Asia's environmental challenges: emergence of new contaminants and advancements in testing methods

Emerging contaminants, including pharmaceuticals, personal care products, microplastics, and per- and poly-fluoroalkyl substances, pose a major threat to both ecosystems and human health in Southeast Asia. As this region undergoes rapid industrialization and urbanization, the increasing presence of unconventional pollutants in water bodies, soil, and various organisms has become an alarming concern. This review comprehensively examines the environmental challenges posed by emerging contaminants in Southeast Asia and recent progress in toxicity testing methods. We discuss the diverse range of emerging contaminants found in Southeast Asia, shedding light on their causes and effects on ecosystems, and emphasize the need for robust toxicological testing methods. This review is a valuable resource for researchers, policymakers, and environmental practitioners working to mitigate the impacts of emerging contaminants and secure a sustainable future for Southeast Asia.

Determining the Surface pKa of Perfluorooctanoic Acid

Perfluorooctanoic acid (PFOA) is an environmentally prevalent and persistent organic pollutant with toxic and bioaccumulative properties. Despite the known importance of perfluorinated pollutants in the global environment, molecular-level details of the physicochemical behavior of PFOA on aqueous interfaces remain poorly understood. Here, we utilized two surface-specific techniques, vibrational sum frequency generation spectroscopy (SFG) and surface tensiometry, to investigate the pH-induced structural changes of PFOA and octanoic acid (OA) and determined the apparent pKa at the air-water surface. The SFG spectra and surface activity model were investigated over a wide range of pHs. With the surface tension measurements, the surface pKa values for OA and PFOA are determined to be 3.8 ± 0.1 and 2.2 ± 0.2, respectively. These results could provide insights into improved remediation of PFOAs and may impact climate modeling of perfluorinated alkyl chain molecules.

Perfluorooctanoate (PFOA) cell-autonomously promotes thermogenic and adipogenic differentiation of brown and white adipocytes

Perfluorooctanoic acid (PFOA) is a synthetic organofluoride surfactant associated with several toxic effects in humans and animals. Particularly, it has been observed that PFOA treatment of mice results in weight loss associated with recruited brown adipose tissue (BAT), including an increased amount of uncoupling protein 1 (UCP1). The molecular mechanism behind this BAT recruitment is presently unknown. To investigate the existence of possible cell-autonomous effects of PFOA, we treated primary cultures of brown and white (inguinal) adipocytes with PFOA, or with the non-fluorinated equivalent octanoate, or with vehicle, for 48 h (from day 5 to day 7 of differentiation). PFOA in itself increased the gene expression (mRNA levels) of UCP1 and carnitine palmitoyltransferase 1A (CPT1α) (thermogenesis-related genes) in both brown and white adipocytes. In addition, PFOA increased the expression of fatty acid binding protein 4 (FABP4) and peroxisome proliferator-activated receptor α (PPARα) (adipogenesis-related genes). Also the protein levels of UCP1 were increased in brown adipocytes exposed to PFOA. This increase was more due to an increase in the fraction of cells that expressed UCP1 than to an increase in UCP1 levels per cell. The PFOA-induced changes were even more pronounced under simultaneous adrenergic stimulation. Octanoate induced less pronounced effects on adipocytes than did PFOA. Thus, PFOA in itself increased the levels of thermogenic markers in brown and white adipocytes. This could enhance the energy metabolism of animals (and humans) exposed to the compound, resulting in a negative energy balance, leading to diminished fitness.

Inulin alleviates perfluorooctanoic acid-induced intestinal injury in mice by modulating the PI3K/AKT/mTOR signaling pathway

Perfluorooctanoic acid (PFOA) is a widely used industrial compound that has been found to induce intestinal toxicity. However, the underlying mechanisms have not been fully clarified and effective interventions are rarely developed. Inulin, a prebiotic, has been used as a supplement in human daily life as well as in gastrointestinal diseases and metabolic disorders. In this study, male mice were exposed to PFOA with or without inulin supplementation to investigate the enterotoxicity and potential intervention effects of inulin. Mice were administered PFOA at 1 mg/kg/day, PFOA with inulin at 5 g/kg/day, or Milli-Q water for 12 weeks. Histopathological analysis showed that PFOA caused colon shortening, goblet cell reduction, and inflammatory cell infiltration. The expression of the tight junction proteins ZO-1, occludin and claudin5 significantly decreased, indicating impaired barrier function. According to the RNA-sequencing analysis, PFOA exposure resulted in 917 differentially expressed genes, involving 39 significant pathways, such as TNF signaling and cell cycle pathways. In addition, the protein expression of TNF-α, IRG-47, cyclinB1, and cyclinB2 increased, while Gadd45γ, Lzip, and Jam2 decreased, suggesting the involvement of the TNF signaling pathway, cell cycle, and cell adhesion molecules in PFOA-associated intestinal injury. Inulin intervention alleviated PFOA-induced enterotoxicity by activating the PI3K/AKT/mTOR signaling pathway and increasing the protein expression of Wnt1, β-catenin, PI3K, Akt3, and p62, while suppressing MAP LC3β, TNF-α, and CyclinE expression. These findings suggested that PFOA-induced intestinal injury, including inflammation and tight junction disruption, was mitigated by inulin through modifying the PI3K/AKT/mTOR signaling pathways. Our study provides valuable insights into the enterotoxic effects of PFOA and highlights the potential therapeutic role of inulin.

Occupational exposure to per- and polyfluoroalkyl substances: a scope review of the literature from 1980-2021

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of chemicals that have been integrated into a wide variety of industrial processes and consumer products since the 1950s. Due to their profuse usage and high persistence in human serum, understanding workplace exposures to PFAS is critical.

OBJECTIVE

We aimed to characterize the PFAS exposure profiles of relevant occupational populations, elucidate trends in the PFAS exposure characterization process, and identify major research gaps that remain within the occupational PFAS exposure literature.

METHODS

A systematic search of four literature databases for peer-reviewed articles published between 1980 and 2021 on PFAS exposure in occupational settings was conducted.

RESULTS

Of the 2574 articles identified, 92 met the inclusion criteria. Fluorochemical workers were the target population in most early exposure assessment research; however, studies conducted within the last 10 years have evaluated a wider range of occupational populations and settings. The highest exposures were reported in fluorochemical workers, but, in comparison to reference populations, one or more PFAS were elevated in most workers and in most workplaces that were assessed. PFAS was most frequently assessed in worker serum using a discrete analytical panel of PFAS, with earlier studies restricted to a few long-alkyl chain PFAS while more recent studies have included more expansive panels due to more robust methods.

SIGNIFICANCE

Characterization of occupational exposure to PFAS is limited but expanding. Current analytical methods are not robust enough to fully capture the potential range of PFAS present across different workers and workplaces. While exposures to PFAS for certain occupational groups have been studied in detail, exposure information for other occupational groups with high potential for exposure are limited. This review highlights substantial findings and major research gaps within the occupational literature.

Effects of perfluorooctanoic acid on Microcystis aeruginosa: Stress and self-adaptation mechanisms

The persistent organic pollutant perfluorooctanoic acid (PFOA) is ubiquitous in aquatic environments. However, little is known about its toxicity to microalgae or the mechanisms by which they may self-adapt to it. We found that growth of the bloom-forming cyanobacterium Microcystis aeruginosa was initially inhibited, with inhibition attenuated after 12 d of PFOA exposure. Growth inhibition gradually decreased and stabilized over time. With increasing PFOA concentration, reactive oxygen species levels and superoxide dismutase and photosystem II activity significantly increased, while respiration, NDH-1 activity, and total carbohydrate content significantly decreased. Self-adaptation mechanisms included antioxidant pathways, energy transfer and distribution of photosystems, and repair of the PSI and NDH complexes. The patterns of change in these parameters were consistent with those of the expression levels of genes in their associated metabolic pathways. Our data suggest that PSII overcompensation might be a strategy by which M. aeruginosa contends with oxidative stress induced by PFOA. Multiple downstream photosynthesis-related proteins were upregulated as a function of PFOA exposure time. These findings may help elucidate physiological, genetic stress and self-adaptive responses of microalgae to PFOA exposure.

Computational estimates of daily aggregate exposure to PFOA/PFOS from 2011 to 2017 using a basic intake model

BACKGROUND

Human exposure to per- and polyfluoroalkyl substances has been modeled to estimate serum concentrations. Given that the production and use of these compounds have decreased in recent years, especially PFOA and PFOS, and that additional concentration data have become available from the US and other industrialized countries over the past decade, aggregate median intakes of these two compounds were estimated using more recent data.

METHODS

Summary statistics from secondary sources were collected, averaged, and mapped for indoor and outdoor air, water, dust, and soil for PFOA and PFOS to estimate exposures for adults and children. European dietary intake estimates were used to estimate daily intake from food.

RESULTS

In accordance with decreased concentrations in media, daily intake estimates among adults, i.e., 40 ng/day PFOA and 40 ng/day PFOS, are substantially lower than those reported previously, as are children's estimates of 14 ng/day PFOA and 17 ng/day PFOS. Using a first-order pharmacokinetic model, these results compare favorably to the National Health and Nutrition Examination Survey serum concentration measurements.

CONCLUSION

Concomitant blood concentrations support this enhanced estimation approach that captures the decline of PFOA/PFOS serum concentration over a decade.

Bioavailability of inhaled or ingested PFOA adsorbed to house dust

Indoor environments may impact human health due to chemical pollutants in the indoor air and house dust. This study aimed at comparing the bioavailability and distribution of PFOA following both an inhalation and an oral exposure to PFOA coated house dust in rats. In addition, extractable organofluorine (EOF) was measured in different tissue samples to assess any potential influence of other organofluorine compounds in the experimental house dust. Blood samples were collected at sequential time points after exposure and at the time of termination; the lungs, liver, and kidney were collected for quantification of PFOA and EOF. The concentration of PFOA in plasma increased rapidly in both exposure groups attaining a C_max at 3 h post exposure. The C_max following inhalation was four times higher compared to oral exposures. At 48 h post exposure, the levels of PFOA in the plasma, liver, and kidney were twice as high from inhalation exposures. This shows that PFOA is readily bioavailable and has a rapid systemic distribution following an inhalation or oral exposure to house dust coated with PFOA. The proportion of PFOA to EOF corresponded to 65-71% and 74-87% in plasma and tissues, respectively. The mass balance between EOF and target PFOA indicates that there might be other unknown PFAS precursor and/or fluorinated compounds that co-existed in the house dust sample that can have accumulated in rats.

Toxicological effects of polystyrene nanoplastics and perfluorooctanoic acid to Gambusia affinis

Plastic pollution has attracted huge attention from public and scientific community in recent years. In the environment, nanoplastics (NPs, <100 nm) can interact with persistent organic pollutants (POPs) such as perfluorooctanoic acid (PFOA) and may exacerbate associated toxic impacts. The present study aims to explore the single and combined ecotoxicological effects of PFOA and polystyrene nanoplastics (PS-NPs, 80 nm) on the PI3K/AKT3 signaling pathway using a freshwater fish model Gambusia affinis. Fish were exposed individually to PS-NPs (200 μg/L) and PFOA (50, 500, 5000 μg/L) and their chemical mixtures for 96 h. Our results showed that the co-exposure significantly altered the mRNA relative expression of PI3K, AKT3, IKKβ and IL-1β, compared to corresponding single exposure and control groups, indicating that the PFOA-NP co-exposure can activate the PI3K/AKT3 signaling pathway. The bioinformatic analyses showed that AKT3 had more probes and exhibited a significantly sensitive correlation with DNA methylation, compared to other genes (PIK3CA, IKBKB, and IL1B). Further, the mRNA expressions of PIK3CA, AKT3, and IKBKB had a significant correlation with copy number variation (CNV) in human liver hepatocellular carcinoma (LIHC). And PIK3CA had the highest mutation rate among other genes of interest for LIHC. Moreover, AKT3 showed a relatively lower expression in TAM and CAF cells, compared to PIK3CA, IKBKB, and IL1B. Besides, hsa-mir-155-5p was closely correlated with AKT3, PIK3CA, IKBKB, and IL1B. In summary, these results provide evidence that NPs could enhance the carcinogenic effects of POPs on aquatic organisms and highlight possible targets of LIHC induced by PFOA-NP co-exposure.

Per-and polyfluoroalkyl substances (PFAS) and persistent chemical mixtures in dust from U.S. colleges

Indoor spaces contain several classes of persistent organic chemicals, including per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). However, concentrations of PFAS and persistent chemical mixtures and their associations with building characteristics on college campuses are understudied. We collected dust from 43 nonresidential spaces on four U.S. college campuses in 2016 and evaluated associations of room characteristics (carpeting, upholstered furniture, and years since last furnished) with dust concentrations of PFAS, PBDEs, PCBs, and OCPs. Nine PFAS, twelve PBDEs, two PCBs, and four OCPs were each detected in at least 75% of the spaces, including several chemicals (e.g., DDT) that have been banned for decades. Concentrations were correlated within and, in some cases, between chemical classes. Wall-to-wall carpeting (compared to rooms without wall-to-wall carpeting) was associated with higher concentrations of six individual PFAS and a mixture of PFAS, and the number of pieces of upholstered furniture was associated with increased concentrations of a mixture of PBDEs. These findings indicate that carpeting and furniture are current sources of PFAS and PBDEs, respectively. Building and finish materials should be carefully selected to avoid exposure to persistent chemicals.

Partial dust removal in vehicles does not mitigate human exposure to organophosphate esters

Organophosphate esters (OPEs) have been detected within car interior dust, suggesting that the indoor microenvironment of vehicles may represent a potential route of human exposure to OPEs. We recently showed that people with longer commutes are exposed to higher concentrations of tris(1,3-dichloro-2-isopropyl)phosphate (TDCIPP) - a widely used OPE - and other studies have suggested that dust removal may lead to lower exposure to chemicals. Therefore, the overall objective of this study was to determine if a decrease in interior car dust results in mitigation of personal OPE exposure. Participants (N = 49) were asked to wear silicone wristbands, and a subset of them wiped interior parts at the front of their vehicles prior to one study week (N = 25) or both study weeks (N = 11). There were no significant differences in total OPE concentrations (77.79-13,660 ng/g) nor individual OPE concentrations (0.04-4852.81 ng/g) across the different wiping groups nor in relation to participant residence ZIP codes and AC/Heater usage. These findings suggest that higher exposure to TDCIPP for participants with longer commutes may be independent of dust located on interior parts at the front of the vehicle. Therefore, our study demonstrates that there is a need for research on the potential contribution of other sources of TDCIPP exposure within car interiors.

Background release and potential point sources of per- and polyfluoroalkyl substances to municipal wastewater treatment plants across Australia

Wastewater treatment plants (WWTPs) are known to be significant sources of per- and polyfluoroalkyl substances (PFAS) to the environment. In this study, PFAS were measured in the influent of 76 municipal wastewater treatment plants (WWTPs) serving approximately 53% of the Australian population. Of fourteen target PFAS, twelve analytes including six C5-C10 perfluoroalkyl carboxylic acids (PFCAs), four C4-10 perfluoroalkyl sulfonic acids (PFSAs) and two fluorotelomer sulfonates (6:2 and 8:2 FTS) were detected. Of these, PFOS, PFHxS and PFHxA had the highest median concentrations. The per capita background release of Σ₁₂ PFAS to WWTP influent in Australia was estimated to be 8.1-24 μg/d/per person. The background release was supplemented by contributions from catchment specific point sources (i.e., industry, airports, military bases, and landfills), whereby the number of industrial sites positively correlated with the per capita mass load of Σ₁₂ PFAS (r = 0.5-0.63, p < 0.01). The per capita mass loads were extrapolated to the entire Australian population, with estimates suggesting that approximately 1 kg/d of Σ₁₂ PFAS reach WWTPs in Australia (300-400 kg annually), with more than half of the PFAS (∼59%) attributed to background release and the remaining (∼41%) to catchment specific point sources. These data provide insight into the release of major PFAS to wastewater at a national scale in Australia.

Immunotoxicity mechanisms of perfluorinated compounds PFOA and PFOS

Perfluorinated and polyfluorinated compounds (PFASs) are a class of synthetic chemical substances that are widely used in human production and life, such as fire-fighting foams, textiles and clothing, surfactants, and surface protective agents. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most abundant and common perfluorinated compounds in biota and humans. Currently, PFOA and PFOS have been listed in the Stockholm Convention on Persistent Organic Pollutants, and their production has been halted in many countries. However, because the high-energy carbon-fluorine bond can make it resistant to hydrolysis, photolysis, microbial degradation, and vertebrate metabolism, PFOA and PFOS show environmental persistence and bioaccumulation and hence, are of great concern to humans and wildlife. PFOA and PFOS have toxic effects on the immune system of the body. This article reviewed the effects of PFOA and PFOS on immune organs such as the spleen, bone marrow, and thymus of mice and zebrafish, and the effects on non-specific immune functions such as the skin barrier, intestinal mucosal barrier, and humoral immunity. We also reviewed the influence of specific immune functions based on cellular immunity, and further summarized the possible immune toxicity mechanisms such as AIM2 inflammasome activation, gene dysregulation, and signal pathway disorders caused by PFOA and PFOS. The aim of this review was to provide a reference for further understanding of the immunotoxicity and the responsible mechanism of PFOA and PFOS.

Prevalence and Implications of Per- and Polyfluoroalkyl Substances (PFAS) in Settled Dust

PURPOSE OF REVIEW

Per- and polyfluoroalkyl substances (PFAS) are a family of more than 7,000 fluorinated compounds. The carbon-fluorine bond of PFAS provides desirable hydrophobic and oleophobic properties and stability that has led to widespread usage in consumer products and industrial applications. The strength of the carbon-fluorine bond also prevents appreciable degradation once released into the environment. Consequently, various household products can release volatile and nonvolatile PFAS into the indoor environment that often concentrate in dust. We discuss the diversity of PFAS in settled dust, emission sources of these chemicals, changes in PFAS profiles in dust over the past century, and the implications for human health.

RECENT FINDINGS

Sources of PFAS found in dust include building materials and furnishings and consumer products used in typical indoor spaces. Daycares and workplaces are emphasized as locations with widespread exposure due to the presence of treated carpeting and industrial-strength cleaners. Comparison and interpretation of findings across studies are complicated by the different ways in which PFAS are screened across studies. We further discuss recent developments in non-targeted software for the comprehensive annotation of PFAS in indoor dust and emphasize the need for comprehensive and harmonized analytical workflows. We highlight the detection and diversity of PFAS in settled dust collected from various indoor spaces, including locations with vulnerable subpopulations. There are opportunities for future research to leverage settled dust as a sentinel environmental matrix to evaluate the link between inhalation and ingestion routes of PFAS exposure to adverse health.

Assessing exposure of semi-volatile organic compounds (SVOCs) in car cabins: Current understanding and future challenges in developing a standardized methodology

Semi-volatile organic compounds (SVOCs) can be found in air, dust and on surfaces in car cabins, leading to exposure to humans via dust ingestion, inhalation, and dermal contact. This review aims at describing current understanding concerning sampling, levels, and human exposure of SVOCs from car cabin environments. To date, several different methods are used to sample SVOCs in car cabin air and dust and there are no standard operating procedures for sampling SVOCs in cars detailed in the literature. The meta-analysis of SVOCs in car cabin air and dust shows that brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) have been most frequently studied, primarily focusing on concentrations in dust. In dust, detected concentrations span over three to seven orders of magnitude, with highest median concentrations for OPFRs, followed by BFRs and, thereafter, polychlorinated biphenyls (PCBs). In air, the variation is smaller, spanning over one to three orders of magnitude, with phthalates and siloxanes having the highest median concentrations, followed by OPFRs, fluorotelomer alcohols (FTOHs) and BFRs. Assessments of human exposures to SVOCs in cars have, so far, mainly focused on external exposure, most often only studying one exposure route, primarily via dust ingestion. In order to perform relevant and complete assessments of human exposure to SVOCs in cars, we suggest broadening the scope to which SVOCs should be studied, promoting more comprehensive external exposure assessments that consider exposure via all relevant exposure routes and making comparisons of external and internal exposure, in order to understand the importance of in-car exposure as a source of SVOC exposure. We also suggest a new sampling approach that includes sampling of SVOCs in both car cabin air and dust, aiming to reduce variability in data due to differences in sampling techniques and protocols.

Per- and polyfluoroalkyl substances (PFAS) and total fluorine in fire station dust

Per- and polyfluoroalkyl substances (PFAS) are a class of over 4700 fluorinated compounds used in industry and consumer products. Studies have highlighted the use of aqueous film-forming foams (AFFFs) as an exposure source for firefighters, but little is known about PFAS occurrence inside fire stations, where firefighters spend most of their shifts. In this study, we aimed to characterize PFAS concentrations and sources inside fire stations. We measured 24 PFAS (using LC-MS/MS) and total fluorine (using particle-induced gamma ray emission) in dust from multiple rooms of 15 Massachusetts stations, many of which (60%) no longer use PFAS-containing AFFF at all and the rest of which only use it very rarely. Compared to station living rooms, turnout gear locker rooms had higher dust levels of total fluorine (p < 0.0001) and three PFAS: perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA), and perfluorodecanoate (PFDoDA) (p < 0.05). These PFAS were also found on six wipes of station turnout gear. By contrast, the dominant PFAS in living rooms was N-ethyl perfluorooctane sulfonamidoacetic acid (N-MeFOSAA), a precursor to perfluorooctane sulfonate (PFOS) that still persists despite phase-outs almost two decades ago. The Σ24 PFAS accounted for less than 2% of fluorine in dust (n = 39), suggesting the potential presence of unknown PFAS. Turnout gear may be an important PFAS source in stations due to intentional additives and/or contamination from firefighting activities.

Assessment of internal exposure to methylsiloxanes in children and associated non-dietary exposure risk

Methylsiloxanes (MSs) are a significant source of indoor environmental pollution due to their high production level and widespread application, and pose a potential health risk. Given the special vulnerability of children to environmental contaminants, assessment of indoor MSs exposure in children is quite essential. In this study, we assessed internal exposure doses and external exposure levels of MSs in children from industrial and residential areas in southwestern China. Indoor air, indoor dust, and personal care product (PCP) samples were collected to evaluate indoor non-dietary MSs exposure in children through various pathways. The concentrations of MSs in indoor environments of industrial areas were approximately one to four orders of magnitude higher than those of residential areas. Sun protection products contained the highest concentrations of MSs. Relatively high levels of cyclic methylsiloxanes (CMSs) were found in plasma of children from industrial areas, which were one to two orders of magnitude higher than those in children from residential areas. The highest MSs levels in plasma were detected in infants (0-1 year), with values of 1.4 × 10² ng/mL and 1.3 × 10² ng/mL for CMSs (D4-D6) and linear methylsiloxanes (LMSs) (L5-L16), respectively. The internal exposure dose of infants in residential areas is driven by major unknown sources of MSs. The average daily doses via inhalation and dust ingestion in children from industrial areas were one to three orders of magnitude higher than in those from residential areas, indicating that these children should be considered a highly exposed population. Inhalation and dust ingestion were both major exposure pathways to MSs for children of all age groups in industrial areas, whereas dermal absorption from PCPs was the predominant exposure pathway for children of all age groups in residential areas (except for infants). Although the exposure risk to D4 and D5 was at an acceptable level for all children studied, the total daily exposure doses of these two cyclic compounds via inhalation for infants in the industrial areas was near the chronic reference dose. Meanwhile, MSs may accumulate in infant plasma within a short period of time (<6 months). Therefore, infants should be the focus of greater attention in future research. As indoor environments may pose high risks for infants in industrial areas, they should be the focus of future research.

Impact of "healthier" materials interventions on dust concentrations of per- and polyfluoroalkyl substances, polybrominated diphenyl ethers, and organophosphate esters

Per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs) are found in building materials and associated with thyroid disease, infertility, and impaired development. This study's objectives were to (1) compare levels of PFAS, PBDEs, and OPEs in dust from spaces with conventional versus "healthier" furniture and carpet, and (2) identify other product sources of flame retardants in situ. We measured 15 PFAS, 8 PBDEs, and 19 OPEs in dust from offices, common areas, and classrooms having undergone either no intervention (conventional rooms in older buildings meeting strict fire codes; n = 12), full "healthier" materials interventions (rooms with "healthier" materials in buildings constructed more recently or gut-renovated; n = 7), or partial interventions (other rooms with at least "healthier" foam furniture but more potential building contamination; n = 28). We also scanned all materials for bromine and phosphorus as surrogates of PBDEs and OPEs respectively, using x-ray fluorescence. In multilevel regression models, rooms with full "healthier" materials interventions had 78% lower dust levels of PFAS than rooms with no intervention (p < 0.01). Rooms with full "healthier" interventions also had 65% lower OPE levels in dust than rooms with no intervention (p < 0.01) and 45% lower PBDEs than rooms with only partial interventions (p < 0.10), adjusted for covariates related to insulation, electronics, and furniture. Bromine loadings from electronics in rooms were associated with PBDE concentrations in dust (p < 0.05), and the presence of exposed insulation was associated with OPE dust concentrations (p < 0.001). Full "healthier" materials renovations successfully reduced chemical classes in dust. Future interventions should address electronics, insulation, and building cross-contamination.

Household low pile carpet usage was associated with increased serum PFAS concentrations in 2005-2006

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the serum of the general US population. Food, drinking water, consumer products, dust, and air have been assessed as PFAS exposure sources for humans. The effects of various types of carpeting on serum PFAS concentrations have been less studied, despite the known use of PFAS in stain-resistant carpet treatments.

OBJECTIVE

This study aimed to examine the associations between serum PFAS concentrations and type of residential flooring among the general US population aged 12 years and older using the 2005-2006 National Health and Nutrition Examination Survey (NHANES).

METHODS

We used multiple linear regressions adjusted for complex survey design and relevant covariates to analyze the relations between serum PFAS concentrations and type of floor covering (smooth surface, low pile carpet, medium to high pile carpet, and combination of carpet and smooth surface), as well as other potential exposure factors. We used multiple imputation to address missing values.

RESULTS

We found significantly higher serum concentrations of perfluorohexane sulfonic acid (PFHxS) and 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (MeFOSAA) in US residents residing in homes with low pile carpeting compared with those residing in homes with smooth surface. We concluded that among US residents aged 12 years and older residing in homes with low pile carpeting in the home in 2005-2006, on average 24% and 19% of the PFHxS and MeFOSAA body burdens, respectively, could be attributed to carpeting. We found associations between other types of floor covering (medium to high pile carpet, combination of carpet and smooth surface) and some PFAS concentrations compared with the smooth surface, but these results were less consistent and generally not statistically significant. Additionally, a group Wald Chi-squared test showed a significant result for PFOS, indicating different contributions of various types of flooring to PFOS serum concentration.

SIGNIFICANCE

Our results are representative of the general US population at the time of the survey, and potentially informative regarding ongoing PFAS exposure from a variety of sources including carpeting.

Bioaccumulation, trophic transfer and biomagnification of perfluoroalkyl acids (PFAAs) in the marine food web of the South China Sea

Knowledge about bioaccumulation and trophic transfer in food webs is of tremendous importance in contaminant hazards evaluation. Perfluoroalkyl acids (PFAAs) are widely distributed, and its emissions to coastal areas have posed a threat to the health of marine organisms and consumers. In this study, 15 species were sampled from Qinzhou Bay of the South China Sea. The concentrations of PFAAs in organisms were detected by liquid chromatography-mass spectrometry, and the trophic positions of organisms were constructed based on nitrogen isotope analysis. PFAAs were found in all organisms. The contents of PFOS in all organisms were higher than of PFOA, and the proportions of short-chain PFAAs were higher in the low trophic positioned organisms, while long-chain PFAAs were higher in the high trophic positioned organisms. Moreover, the bioaccumulation factors (BAFs) increased with the increasing number of fluorocarbon atoms. The trophic magnification factor (TMF) and the biomagnification factors (BMFs), calculated from the constructed food webs, together suggested potential biomagnification effects of PFOS, while less clear results were found for PFOA. Our results further indicate that previously banned long-chain PFAAs had persistent residuals in this coastal marine ecosystem, and that emerging short-chain PFAAs had high concentrations in some species but showed no biomagnification.

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

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

An Overview of Per- and Polyfluoroalkyl Substances (PFAS) in the Environment: Source, Fate, Risk and Regulations

The current article reviews the state of art of the perfluoroalkyl and polyfluoroalkyl substances (PFASs) compounds and provides an overview of PFASs occurrence in the environment, wildlife, and humans. This study reviews the issues concerning PFASs exposure and potential risks generated with a focus on PFAS occurrence and transformation in various media, discusses their physicochemical characterization and treatment technologies, before discussing the potential human exposure routes. The various toxicological impacts to human health are also discussed. The article pays particular attention to the complexity and challenging issue of regulating PFAS compounds due to the arising uncertainty and lack of epidemiological evidence encountered. The variation in PFAS regulatory values across the globe can be easily addressed due to the influence of multiple scientific, technical, and social factors. The varied toxicology and the insufficient definition of PFAS exposure rate are among the main factors contributing to this discrepancy. The lack of proven standard approaches for examining PFAS in surface water, groundwater, wastewater, or solids adds more technical complexity. Although it is agreed that PFASs pose potential health risks in various media, the link between the extent of PFAS exposure and the significance of PFAS risk remain among the evolving research areas. There is a growing need to address the correlation between the frequency and the likelihood of human exposure to PFAS and the possible health risks encountered. Although USEPA (United States Environmental Protection Agency) recommends the 70 ng/L lifetime health advisory in drinking water for both perfluorooctane sulfonate (PFO) perfluorooctanoic acid (PFOA), which is similar to the Australian regulations, the German Ministry of Health proposed a health-based guidance of maximum of 300 ng/L for the combination of PFOA and PFOS. Moreover, there are significant discrepancies among the US states where the water guideline levels for the different states ranged from 13 to 1000 ng L−1 for PFOA and/or PFOS. The current review highlighted the significance of the future research required to fill in the knowledge gap in PFAS toxicology and to better understand this through real field data and long-term monitoring programs.

Per- and Polyfluoroalkyl Substances in Dust Collected from Residential Homes and Fire Stations in North America

Over the past few years, human exposure to per- and polyfluoroalkyl substances (PFAS) has garnered increased attention. Research has focused on PFAS exposure via drinking water and diet, and fewer studies have focused on exposure in the indoor environment. To support more research on the latter exposure pathway, we conducted a study to evaluate PFAS in indoor dust. Dust samples from 184 homes in North Carolina and 49 fire stations across the United States and Canada were collected and analyzed for a suite of PFAS using liquid and gas chromatography-mass spectrometry. Fluorotelomer alcohols (FTOHs) and di-polyfluoroalkyl phosphoric acid esters (diPAPs) were the most prevalent PFAS in both fire station and house dust samples, with medians of approximately 100 ng/g dust or greater. Notably, perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate, perfluorononanoic acid, and 6:2 diPAP were significantly higher in dust from fire stations than from homes, and 8:2 FTOH was significantly higher in homes than in fire stations. Additionally, when comparing our results to earlier published values, we see that perfluoroalkyl acid levels in residential dust appear to decrease over time, particularly for PFOA and PFOS. These results highlight a need to better understand what factors contribute to PFAS levels in dust and to understand how much dust contributes to overall human PFAS exposure.

Environmental levels and human body burdens of per- and poly-fluoroalkyl substances in Africa: A critical review

Per- and polyfluoroalkyl substances (PFASs) are known organic pollutants with adverse health effects on humans and the ecosystem. This paper synthesises literature about the status of the pollutants and their precursors, identifies knowledge gaps and discusses future perspectives on the study of PFASs in Africa. Limited data on PFASs prevalence in Africa is available because there is limited capacity to monitor PFASs in African laboratories. The levels of PFASs in Africa are higher in samples from urban and industrialized areas compared to rural areas. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the dominant PFASs in human samples from Africa. Levels of PFOS and PFOA in these samples are lower than or comparable to those from industrialized countries. PFOA and PFOS levels in drinking water in Africa are, in some cases, higher than the EPA drinking water guidelines suggesting potential risk to humans. The levels of PFASs in birds' eggs from South Africa are higher, while those in other environmental media from Africa are lower or comparable to those from industrialized countries. Diet influences the pollutant levels in fish, while size and sex affect their accumulation in crocodiles. No bioaccumulation of PFASs in aquatic systems in Africa could be confirmed due to small sample sizes. Reported sources of PFASs in Africa include municipal landfills, inefficient wastewater treatment plants, consumer products containing PFASs, industrial wastewater and urban runoff. Relevant stakeholders need to take serious action to identify and deal with the salient sources of PFASs on the African continent.

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

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

Per- and polyfluoroalkyl substances in paired dust and carpets from childcare centers

Carpets can be a significant source of per- and polyfluoroalkyl substances (PFASs) in the indoor environment and may be an especially important source of exposure for children and toddlers. Most previous studies focused on measuring indoor dust only. In this study, we measured PFAS concentrations in paired carpet and dust samples from 18 California childcare centers in 2018 to investigate carpet as a contributor to PFASs in dust. Median total PFAS concentrations (∑PFASs) in carpets and dust were 471 ng/g and 523 ng/g, respectively. 6:2 FTOH and 6:2 FTSA were the two dominant PFASs, collectively accounting for over 50% of the ∑PFASs in both media. Other frequently detected PFASs included C₄-C₁₄ perfluoroalkylcarboxylic acids, C₄-C₈ perfluoroalkylsulfonic acids, PFDS, 4:2 FTSA, 8:2 FTSA, FOSA, MeFOSE, EtFOSE, 8:2 FTOH, and 10:2 FTOH. We found strong associations between PFAS levels in carpet and dust pairs, suggesting that carpets can be a source and a sink for PFASs. The estimated total perfluoroalkyl acids (PFAA) intake via dust ingestion for children was 0.023, 0.096, and 1.9 ng/kg body weight/day in the low-, intermediate-, and high-exposure scenarios, respectively. Our data suggest that PFASs of emerging concern are playing an increasingly important role in indoor exposure to PFASs.

Urban-level environmental factors related to pediatric asthma

During the 20th century, urbanization has increasing and represented a major demographic and environmental change in developed countries. This ever-changing urban environment has an impact on disease patterns and prevalence, namely on noncommunicable diseases, such as asthma and allergy, and poses many challenges to understand the relationship between the changing urban environment and the children health. The complex interaction between human beings and urbanization is dependent not only on individual determinants such as sex, age, social or economic resources, and lifestyles and behaviors, but also on environment, including air pollution, indoors and outdoors, land use, biodiversity, and handiness of green areas. Therefore, the assessment and identification of the impact of urban environment on children's health have become a priority and many recent studies have been conducted with the goal of better understanding the impacts related to urbanization, characterizing indoor air exposure, identifying types of neighborhoods, or characteristics of neighborhoods that promote health benefits. Thus, this review focuses on the role of urban environmental factors on pediatric asthma.

An in vitro and in silico investigation of human pregnane X receptor agonistic activity of poly- and perfluorinated compounds using the heuristic method-best subset and comparative similarity indices analysis

Poly- and perfluorinated compounds (PFCs) may induce potential endocrine-disrupting hormonal effects. However, the molecular mechanism of the toxicology of PFCs remains unclear, and the insufficient information is available on the biological activities of PFCs at present. In this study, the cell-based reporter gene assays were used to determine the agonistic activity of PFCs on the human pregnane X receptor (hPXR). The heuristic method combined with best subset modeling (HM-BSM) based on Dragon descriptors and comparative similarity indices analysis (CoMSIA) were employed to build classical quantitative structure-activity relationship (QSAR) and three-dimensional QSAR models, respectively. The applicability domain (AD) of the classical QSAR model was assessed. Both the HM-BSM and CoMSIA approaches demonstrated good robustness, predictive ability, and mechanistic interpretability. The r² and leave-one-out cross-validation squared correlated coefficient (q²_LOO) values were 0.872 and 0.759 for the HM-BSM, and 0.976 and 0.751 for the CoMSIA model, respectively. The hPXR agonistic activity of the PFCs predicted by the built HM-BSM and CoMSIA agreed well with experimental activity, with root mean square error (RMSE) values of 0.0803 and 0.117, respectively, and external validation squared correlated coefficients (q²_EXT) of 0.972 and 0.932, respectively. The hPXR agonistic activity of PFCs was related to their molecular polarizability, charge and atomic mass. Hydrogen bonding and hydrophobic interactions constituted the primary intermolecular forces between PFCs and the hPXR. The developed models were used to screen the PFCs with high hPXR agonistic activity.

Acute PFOA exposure promotes epigenomic alterations in mouse kidney tissues

Perfluorooctanoic acid (PFOA), a manufactured perfluorochemical is a common surfactant and environmental pollutant found in various consumer products and water sources. Epidemiological studies have demonstrated its association with kidney dysfunction. However, the mechanisms that trigger kidney dysfunction following PFOA exposure is a gap in the field. The work presented explores the potential epigenetic indicators of kidney disease due to exposure to PFOA. In this study, 30 days old CD-1 mice were exposed to 1, 5, 10, or 20 mg/kg/day of PFOA for 10 days. Following acute oral exposure, epigenetic alterations and expression levels of various markers of fibroblast activation were evaluated in kidney tissues. We noted that PFOA-exposed mice exhibited differential methylation yielding 879 differentially methylated regions compared to vehicle. The mRNA expression revealed significant increase in Dnmt1 with decreased Rasal1 expression at higher levels of PFOA exposure suggestive of Rasal1 hypermethylation (an early indicator of fibroblast activation in kidney). Like Dnmt1, we also observed significant increase in Hdac1, 3 and 4. These are class I & II HDACs which are known to be critically altered in some renal diseases. Further, the mRNA expression levels of TGF-β and α-SMA significantly increased compared to vehicle. The KEGG and Go enrichment pathway analysis of reduced representation bisulfite data also revealed pathways implicated in renal fibrosis. Our study shows clear evidence of epigenetic alterations (DNA methylation and HDAC expression changes) in tissues from mouse kidney following PFOA exposure. Our results also suggest that epigenetic alterations in kidney promote the expression of early markers of fibroblast activation.

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

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

Perfluoroalkyl substances (PFASs) in air-conditioner filter dust of indoor microenvironments in Greece: Implications for exposure

The occurrence of perfluoroalkyl substances (PFASs) was for the first time investigated in various working microenvironments (internet cafes, electronics shops, coffee shops, restaurants, etc.) in Thessaloniki, Greece, using the dust trapped by central air conditioner (A/C) filters. Perfluorooctane sulfonic acid (PFOS) was found in the range from 16 to 227 ng g^-1, however it was detectable in only 30% of samples. On the contrary, perfluorohexanoic acid (PFHxA) was found in 85% of samples in the range from 3.6 to 72.5 ng g^-1, while 90-95% of samples exhibited perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDcA) and perfluorododecanoic acid (PFDoDA) in the range from 10-653 ng g^-1, 3.2-7.4 ng g^-1 and 3.8-13.1 ng g^-1, respectively. The PFAS profile varied largely among the different microenvironment categories suggesting different sources. Estimated daily intakes through dust ingestion were calculated.

Characteristic and human exposure risk assessment of per- and polyfluoroalkyl substances: A study based on indoor dust and drinking water in China

Per- and polyfluoroalkyl Substances (PFAS) are ubiquitous in the environmental matrix, and their eco-toxicity on wide life and health risks on humans arising concerns. Due to the information gap, current risk assessments of PFAS ignore the indoor exposure pathway such as indoor dust and the different sources of drinking water. We collected and analyzed 168 indoor dust and 27 drinking water samples (including tap water, filtered water and bottled water). The mean concentrations of six typical PFAS measured in indoor dust and drinking water are in the range of 15.13-491.07 ng g^-1 and 0.31-4.14 ng L^-1, respectively. For drinking water, PFOA and PFOS were the dominant compounds, while PFHxS was the most abundant in indoor dust. Short-chain PFAS concentrations were higher than long-chain PFAS in both drinking water and indoor dust. Higher concentration of PFAS was observed in tap water and filtered water than bottled water. The total daily intake (TDI) of six PFAS are 20.67-52.97 ng kg^-1 d^-1 for infants, children, teenagers, and adults. As to children, teenagers, and adults, perfluorooctanoate (PFOA) is the major compound, accounting for 72.9-74.7% of the total daily intake. And PFOA (38.7%) and perfluorooctane sulfonate (PFOS, 42.2%) are the dominant PFAS for infants. The quantitative proportions of exposure sources are firstly revealed in this study, which in the order of foodstuff > indoor dust > drinking water > indoor air. Although the contribution to the PFAS intake of drinking water and indoor dust was not predominant (<9%), the health risks caused by long-term exposure need our attention. The hazard quotient (HQ) values of total PFAS were in the range of 0.154-0.498, which suggesting the relatively lower exposure risk in Chinese population. This study provides important reference to understand PFAS exposure status other than foodstuff.

Accumulation, biodegradation and toxicological effects of N-ethyl perfluorooctane sulfonamidoethanol on the earthworms Eisenia fetida exposed to quartz sands

While N-ethyl perfluorooctane sulfonamidoethanol (EtFOSE) is a precursor of perfluorooctane sulfonate (PFOS), its bioaccumulation, transformation and toxicological effects in earthworms (Eisenia fetida) exposed to quartz sands are poorly understood. The present study showed that except for parent EtFOSE, N-ethylperfluorooctane sulfonamide acetate (EtFOSAA), N-ethyl perfluorooctane sulfonamide (EtFOSA), perfluorooctane sulfonamide acetate (FOSAA), perfluorooctane sulfonamide (FOSA) and PFOS were detected in earthworms, with EtFOSAA as the primary biotransformation product. The biota-to-sand accumulation factor (BSAF) and uptake rate coefficient (k_u) of EtFOSE were 5.7 and 0.542/d, respectively. The elimination rate constants (k_e) decreased in the order EtFOSA (0.167/d) ∼ FOSAA (0.147/d) > FOSA (0.119/d) ∼ EtFOSAA (0.117/d) > EtFOSE (0.095/d) > PFOS (0.069/d). No significant effects were observed in malondialdehyde (MDA) contents and acetylcholinesterase (AChE) activities between EtFOSE treatments and controls. EtFOSE could cause significant accumulation of reactive oxygen species (ROS) in earthworms. Peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were significantly activated by 41.4-74.3%, 37.2-44.4% and 32.4-52.3% from day 4-10, respectively, while 8-Hydroxy-2-deoxyguanosine (8-OHdG) levels were elevated by 47.7-70.3% from day 8-10, demonstrating that EtFOSE induced oxidative stress and oxidative DNA damage in earthworms. Significant increase of glutathione-S-transferase (GST) with 41.6-62.8% activation (8-10 d) gave indirect evidence on the conjugation of EtFOSE or its corresponding metabolites during phase II of detoxication. This study provides important information on the fate and potential risks of EtFOSE to terrestrial invertebrates.

Occurrence and human exposure assessment of perfluorinated substances in house dust from three European countries

65 house dust samples from three European countries (Belgium, Italy and Spain) were evaluated for the presence of 20 polyflouroalkyl substances (PFASs) including perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acid (PFCAs) and perfluoroalkane sulfonamides (PFOSAs). The three countries presented similar PFAS levels ranging from 3.13 to 155 ng/g (12.9 ng/g; median), but in all cases PFCAs concentrations (6.92, 15.2 and 8.68 ng/g; median for Belgium, Italy and Spain) were higher than those obtained for PFSAs (2.30, 1.76 and 2.68 ng/g). Interestingly, in comparison to previously published data exhibited an increase in perfluorobutanesulfonate (PFBS) concentrations in Belgian house dust. On the other hand, levels of perfluorooctanesulfonate (PFOS) decreased in Spanish case. Data were examined for relationships between PFAS house dust levels, building and outdoor surrounding characteristics and occupant habits. Main findings revealed a positive association between PFOS concentrations and the building edification age, which could highlight a decrease in the use of this chemical in Europe. Similarly, perfluorohexanesulfonate (PFHxS) levels correlated with the percentage of the floor covered by textiles. Homes located in industrial sites showed higher PFCA levels compared to urban or agricultural locations, revealing the industrial processes as a potential source of these chemicals in Europe. Data obtained were used to perform human exposure assessment for dust intake via oral ingestion. Estimated daily intakes, calculated for toddlers and adults at median and worst case scenarios, were below oral Reference Dose (RfD) and tolerable daily intakes (TDI). However, in perfluorooctanoic acid (PFOA) case, dust ingestion significance to total dietary exposure reached values of 51% for toddlers in the worst case scenario.

Reduction of hazardous chemicals in Swedish preschool dust through article substitution actions

Consumer goods and building materials present in the preschool environment can be important sources of hazardous chemicals, such as plasticizers, bisphenols, organophosphorus and brominated flame retardants, poly- and perfluoroalkyl substances, which may pose a health risk to children. Even though exposure occurs via many different pathways, such as food intake, inhalation, dermal exposure, mouthing of toys etc., dust has been identified as a valuable indicator for indoor exposure. In the present study, we evaluate the efficiency of product substitution actions taken in 20 Swedish preschools from the Stockholm area to reduce the presence of hazardous substances in indoor environments. Dust samples were collected from elevated surfaces in rooms where children have their everyday activities, and the concentrations found were compared to the levels from a previous study conducted in 2015 at the same preschools. It was possible to lower levels of hazardous substances in dust, but their continued presence in the everyday environment of children was confirmed since bisphenol A, restricted phthalates and organophosphate esters were still detectable in all preschools. Also, an increase in the levels of some of the substitutes for the nowadays restricted substances was noted; some of the alternative plasticizers to phthalates, such as DEHA and DEHT, were found with increased concentrations. DINP was the dominant plasticizer in preschool dust with a median concentration of 389 μg/g, while its level was significantly (p = 0.012) higher at 716 μg/g in preschools with polyvinyl chloride (PVC) flooring. PBDEs were now less frequently detected in dust and their levels decreased 20% to 30%. This was one of the few times that PFAS were analyzed in preschool dust, where 6:2 diPAP was found to be most abundant with a median concentration of 1140 ng/g, followed by 6:2 PAP 151 ng/g, 8:2 diPAP 36 ng/g, N-Et-FOSAA 18 ng/g, PFOS 12 ng/g, PFOA 7.7 ng/g and PFNA 1.1 ng/g. In addition, fluorotelomer alcohols were detected in 65-90% of the samples. Children's exposure via dust ingestion was evaluated using intermediate and high daily intake rates of the targeted chemicals and established health limit values. In each case, the hazard quotients (HQs) were < 1, and the risk for children to have adverse health effects from the hazardous chemicals analyzed in this study via dust ingestion was even lower after the product substitution actions were taken in preschools.

Exposure to indoor endocrine-disrupting chemicals and childhood asthma and obesity

BACKGROUND

Indoor air contaminants may act as endocrine-disrupting chemicals (EDCs). However, to what extent these contaminants affect health is poorly known. We aimed to assess the association between EDCs exposure and asthma, respiratory symptoms and obesity in schoolchildren.

METHODS

Data from a cross-sectional analysis of 815 participants from 20 schools in Porto, Portugal, were analysed. Symptoms were assessed, asthma was defined on lung function, and airway reversibility and body mass index (BMI) were calculated. The concentrations of 13 volatile organic compounds and 2 aldehydes identified as EDCs were measured in 71 classrooms throughout 1 week. Principal component analysis (PCA) was used to assess the effect of co-exposure. Associations were estimated by regression coefficients using linear and logistic regression models.

RESULTS

Increased individual and combined EDCs levels were found in classrooms having more children with asthma and obesity. Higher levels of hexane, styrene, cyclohexanone, butylated hydroxytoluene and 2-butoxyethanol were associated with obesity, and higher levels of cyclohexanone were associated with increased child BMI. Toluene, o-xylene, m/p-xylene and ethylbenzene were significantly associated with nasal obstruction. A positive association was found between PC1 and the risk of obese asthma (OR = 1.43, 95% CI 1.01, 1.98) and between PC2 and overweight (OR = 1.51, 95% CI 1.28, 1.79). PC1 and PC2 were also associated with nasal obstruction, and PC2 was associated with breathing difficulties and lean body mass, although EDCs concentrations were low.

CONCLUSIONS

Our findings further support the role of EDCs in asthma and obesity development. Moreover, even low levels of indoor exposure may influence the risk of asthma, respiratory symptoms and obesity.

Per- and polyfluorinated compounds in saleswomen's urine linked to indoor dust in clothing shops

This study aims to investigate the characteristics of typical per- and polyfluorinated compounds (PFCs) in indoor dust from clothing shops and urine sampled from saleswomen. A total of 58 indoor dust samples and 73 urine samples from saleswomen were collected from clothing shops in Shanghai, China. All samples were analyzed for PFCs using high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS). The mean PFC concentrations in indoor dust ranged from 0.42 (PFDA) to 5.04 ng g^-1 (PFDoA). PFDoA and PFHxS were the most prominent PFCs, with median concentrations of 2.95 ng g^-1 and 1.49 ng g^-1, respectively. The median PFC concentrations in urine ranged from 10.15 (PFDS) to 666.1 ng l^-1 (PFOA) and PFOA was the most abundant chemical with concentrations ranging from 207 to 907 ng l^-1. A significant positive correlation was obtained between long-chain PFCs in dust and in urine (p < 0.01). Daily intake values of PFCs via dust ingestion were also calculated, and even under high-end exposure scenarios, the intake of PFOA (36.5 pg day^-1) and PFOS (56.7 pg day^-1) were well within the tolerable daily intake values. These results are important to both characterize PFC levels and estimate the saleswomen's exposure to PFCs from indoor dust.

Does soil track-in contribute to house dust concentrations of perfluoroalkyl acids (PFAAs) in areas affected by soil or water contamination?

The Minnesota Department of Health measured levels of perfluoroalkyl acids (PFAAs) in house dust at homes in communities impacted by PFAA-contaminated soil and drinking water to determine whether PFAAs in soil outside the home are associated with concentrations in dust. House dust samples from both interior living spaces and entryways to the yard were collected and analyzed separately based on the presumption that PFAAs in entryway dust may better reflect "track-in" of PFAAs into the home from contaminated soil or lawns irrigated with contaminated water. PFAA detections and concentrations in living rooms were significantly higher compared to entryways; and concentrations in both sampling locations were higher than corresponding soil concentrations, suggesting that interior sources were the main contributors to PFAAs in house dust. PFAA dust concentrations in entryways were significantly associated with living room dust levels for all analytes except PFBA. Relationships between entryway dust and soil were only seen for one PFAA (PFOA). However, median concentrations of PFOA in entryway and living room dust were 35 and 70 times higher (respectively) than in soil, which highlights the lack of importance of PFAA soil track-in as a contributor to dust concentration in this setting. Due to the small sample size, larger scale studies are needed to further assess the potential for migration of PFAA contaminated soil to indoor dust.

Hand Wipes: A Useful Tool for Assessing Human Exposure to Poly- and Perfluoroalkyl Substances (PFASs) through Hand-to-Mouth and Dermal Contacts

The indoor environment contributes considerably to human exposure to poly- and perfluoroalkyl substances (PFASs). This study estimated the human exposure to PFASs from the indoor environment through hand-to-mouth and dermal contacts using hand wipes. An analytical method was developed to determine 25 PFASs in hand wipe samples collected as a composite sample from both hands of 60 adults. Polyfluoroalkyl phosphate esters (PAPs) were the predominant PFASs in the hand wipe samples (medians between 0.21 and 0.54 ng per sample). Positive and significant correlations were observed between PAPs, perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) in hand wipes. Low frequency of daily hand washing (≤8 times day^-1) was associated with 30-50% higher concentrations of PFOS, PFOA, and 8:2diPAP in hand wipes. Further, significant correlations between paired hand wipes and house dust samples were observed for PFOS, PFOA, and 6:2diPAP. Also, a significant correlation between PFOS in hand wipes and EtFOSE in indoor air was found. This finding indicates either a common source of exposure or a transformation of EtFOSE to PFOS in the environment or on the hands. The contributions of direct and indirect exposure to perfluoroalkyl acids (PFAAs) showed that PFOA contributed the highest exposure to adults via hand-to-mouth and dermal contacts, followed by PFOS. The median of estimated daily intakes via hand-to-mouth and dermal contacts (for hands only) for PFOA were 0.83 and 0.50 pg·kg bw^-1·day^-1, respectively. This study gives a first indication that PFAS concentrations in hand wipes can be used as a proxy for the exposure to PFASs from indoor environments, but further studies are needed to confirm this.

Per- and polyfluoroalkyl substances in Northern California cats: Temporal comparison and a possible link to cat hyperthyroidism

The indoor environment and dietary intake are considered to be major human exposure pathways to per- and polyfluoroalkyl substances (PFASs). Cats have similar exposures to humans by sharing their residential environments, although they have different diet, body sizes, and indoor activities. In the present study, we report PFAS levels in the serum of 2 groups of Northern California cats (>10 yr old) collected during 2 time periods: 2008 to 2010 (n = 21) and 2012 to 2013 (n = 22). Levels of ∑PFAS (geometric mean) were lower in the second period (geometric mean = 8.10 ng/mL) than the first time period (geometric mean = 15.8 ng/mL), although PFAS profiles remained similar. We also analyzed PFAS levels in human serum collected in the same time period (2008-2010) and geographic area, and compared the profiles and ∑PFAS levels (15.8 vs 14.3 ng/mL for cat and human, respectively). Long chain perfluorinated carboxylic acids, especially perfluorononanoic acid and perfluoroundecanoic acid, were significantly higher in cat serum than in humans. Furthermore, serum from hyperthyroid cats in the second time period showed higher ∑PFAS level (9.50 ng/mL) compared to nonhyperthyroid cats (7.24 ng/mL), and it is the perfluorooctanoic acid levels that were statistically significantly higher in hyperthyroid cats' serum (p < 0.05). This result may indicate a possible link between PFAS levels and cat hyperthyroid, warranting a larger study for further investigation. Environ Toxicol Chem 2018;37:2523-2529. © 2018 SETAC.

A mass estimate of perfluoroalkyl substance (PFAS) release from Australian wastewater treatment plants

Perfluoroalkyl substances (PFASs) have been used in large quantities for a variety of applications in Australian industry and household products. Through the course of their everyday use, PFASs enter the wastewater stream however current treatment processes provide only partial removal of these chemicals from wastewater. The release of treated effluent and re-use of biosolids represents an important point source of PFASs into the Australian environment yet the scale of PFAS release from Australian WWTPs is unknown. For the first time, influent, effluent and biosolids samples from 14 WWTPs across Australia were assessed for 9 PFASs and the national loads of these PFASs released from WWTPs estimated. Ʃ9PFASs ranged from 0.98 to 440 ng/L (influent), 21-560 ng/L (effluent) and 5.2-150 ng/g (biosolids). National loads of PFOA and PFOS in effluent were estimated at 65 kg and 26 kg per annum respectively. In biosolids, annual loads were estimated at 2 kg and 8 kg respectively. The continued detection of PFOS over a decade after its phase out, the increasing use of PFOS alternatives together with their resistance to degradation processes suggests that PFASs will be a priority for regulators and waste management to prevent further contamination of Australia's water resources.

Perfluoroalkyl acids and their precursors in floor dust of children's bedrooms - Implications for indoor exposure

We analysed floor dust samples from 65 children's bedrooms in Finland collected in 2014/2015 for 62 different per- and polyfluoroalkyl substances (PFASs) with a simple and highly efficient method. Validation results from the analysis of standard reference material (SRM) 2585 were in good agreement with literature data, while 24 PFASs were quantified for the first time. In the dust samples from children's bedrooms, five perfluoroalkyl carboxylic acids (PFCAs) and perfluorooctane sulfonic acid (PFOS) were detected in more than half of the samples with the highest median concentration of 5.26 ng/g for perfluorooctanoic acid (PFOA). However, the dust samples were dominated by polyfluoroalkyl phosphoric acid esters (PAPs) and fluorotelomer alcohols (FTOHs) (highest medians: 53.9 ng/g for 6:2 diPAP and 45.7 ng/g for 8:2 FTOH). Several significant and strong correlations (up to ρ = 0.95) were found among different PFASs in dust as well as between PFASs in dust and air samples (previously published) from the same rooms. The logarithm of dust to air concentrations (log K_dust/air) plotted against the logarithm of the octanol-air partition coefficient (log K_oa) resulted in a significant linear regression line with R² > 0.88. Higher dust levels of PFOS were detected in rooms with plastic flooring material in comparison to wood (p < 0.05). Total estimated daily intakes via dust (EDI_dust) and air (EDI_air) of perfluoroalkyl acids (PFAA), including biotransformation of precursors to PFAAs, were calculated for 10.5-year-old children. The total EDI_dust for PFOA and PFOS were estimated to be 0.007 ng/kg bw/day and 0.006 ng/kg bw/day, respectively, in an intermediate exposure scenario. The sum of the total EDIs for all PFAAs was slightly higher for dust than air (0.027 and 0.019 ng/kg bw/day). Precursor biotransformation was generally important for total PFOS intake, while for the PFCAs, FTOH biotransformation was estimated to be important for air, but not for dust exposure.

Time Trends in Per- and Polyfluoroalkyl Substances (PFASs) in California Women: Declining Serum Levels, 2011-2015

After several decades of widespread use, some per- and polyfluoroalkyl substances (PFASs) were phased-out of use due to concerns raised by their persistent, bioaccumulative, and toxic properties. Our objective was to evaluate temporal trends in serum PFAS levels among 1257 middle-aged and older California women (ages 40-94) during a four year period, beginning approximately 5-10 years after these phase-outs began. An online SPE-HPLC-MS/MS was used to measure 10 long-chain PFASs in serum from blood collected cross-sectionally during 2011-2015 from a subset of participants in the California Teachers Study. Results from multivariable linear regression analyses indicated that serum concentrations of nearly all PFASs declined on average 10% to 20% per year. Serum levels of perfluorohexanesulfonic acid (PFHxS) did not significantly decline. With the exception of PFHxS, the downward trend in serum concentrations was evident for all PFASs across all ages, although declines were comparatively steeper among the oldest women. These findings suggest that the phase-out of some common PFASs has resulted in reduced human exposures to them. The lack of a decline for PFHxS suggests that these exposures may be ongoing and underscores the importance of continued biomonitoring and research efforts to elucidate current pathways of exposure.