Brominated flame retardants and perfluoroalkyl acids in groundwater, tile drainage, soil, and crop grain following a high application of municipal biosolids to a field

Burning question: Rethinking organohalide degradation strategy for bioremediation applications

Organohalides are widespread pollutants that pose significant environmental hazards due to their high degree of halogenation and elevated redox potentials, making them resistant to natural attenuation. Traditional bioremediation approaches, primarily relying on bioaugmentation and biostimulation, often fall short of achieving complete detoxification. Furthermore, the emergence of complex halogenated pollutants, such as per- and polyfluoroalkyl substances (PFASs), further complicates remediation efforts. Therefore, there is a pressing need to reconsider novel approaches for more efficient remediation of these recalcitrant pollutants. This review proposes novel redox-potential-mediated hybrid bioprocesses, tailored to the physicochemical properties of pollutants and their environmental contexts, to achieve complete detoxification of organohalides. The possible scenarios for the proposed bioremediation approaches are further discussed. In anaerobic environments, such as sediment and groundwater, microbial reductive dehalogenation coupled with fermentation and methanogenesis can convert organohalides into carbon dioxide and methane. In environments with anaerobic-aerobic alternation, such as paddy soil and wetlands, a synergistic process involving reduction and oxidation can facilitate the complete mineralization of highly halogenated organic compounds. Future research should focus on in-depth exploration of microbial consortia, the application of ecological principles-guided strategies, and the development of bioinspired-designed techniques. This paper contributes to the academic discourse by proposing innovative remediation strategies tailored to the complexities of organohalide pollution.

PFAS fate using lysimeters during degraded soil reclamation using biosolids

Carbon- and nutrient-rich biosolids are used in agriculture and land reclamation. However, per- and polyfluoroalkyl substances (PFAS) typically present in biosolids raise concerns of PFAS leaching to groundwater and plant uptake. Here, we investigated PFAS persistence and leaching from biosolids applied to a site constructed artificially to mimic degraded soils. Treatments included biosolids and biosolids blended with mulch applied at different rates to attain either one and five times the agronomic N rate for vegetable crops and a control treatment with synthetic urea and triple superphosphate fertilizer. Leachates were collected for a 2-year period from 15-cm depth zero-tension drainage lysimeters. Soils were analyzed post biosolids application. PFAS were quantified using isotope-dilution, solid-phase extraction and liquid chromatography tandem mass spectrometry. Leachate profiles exemplified an initial high total PFAS concentration, followed by a sharp decline and subsequent small fluctuations attributed to pre-existing soil conditions and rainfall patterns. Quantifiable PFAS in leachate were proportional to biosolids application rates. Short-chain perfluoroalkyl acids (CF2 < 6) were dominant in leachate, while the percentage of longer chains homologues was higher in soils. A 43% biosolids blend with mulch resulted in 21% lower PFAS leachate concentrations even with the blend application rate being 1.5 times higher than biosolids due to the blend's lower N-content. The blending effect was more pronounced for long-chain perfluoroalkyl sulfonic acids that have a greater retention by soils and the air-water interface. Biosolids blending as a pragmatic strategy for reducing PFAS leachate concentrations may aid in the sustainable beneficial reuse of biosolids.

Debromination of novel brominated flame retardants using Zn-based additives: A viable thermochemical approach in the mitigation of toxic effects during e-waste recycling

Brominated flame retardants (BFRs) are bromine-bearing additives added to the polymeric fraction in various applications to impede fire ignition. The Stockholm Convention and various other legislations abolished legacy BFRs usage and hence, the so-called novel BFRs (NBFRs) were introduced into the market. Recent studies spotlighted their existence in household dust, aquifers and aquatic/aerial species. Co-pyrolysis of BFRs with metal oxides has emerged as a potent chemical recycling approach that produces a bromine-free stream of hydrocarbon. Herein, we investigate the debromination of two prominent two NBFRs; namely tetrabromobisphenol A 2,3-dibromopropyl ether (TD) and tetrabromobisphenol A diallyl ether (TAE) through their co-pyrolysis with zinc oxide (ZnO) and franklinite (ZnFe2O4). Most of the zinc content in electrical arc furnace dust (EAFD) exists in the form of these two metal oxides. Conversion of these metal oxides into their respective bromides could also assist in the selective extraction of the valuable zinc content in EAFD. The debromination potential of both oxides was unveiled via a multitude of characterization studies to analyze products (char, gas and condensates). The thermogravimetric analysis suggested a pyrolytic run up to 500 °C and the TAE treatment with ZnO produced only a trivial amount of brominated compounds (relative area, 0.83%). Phenol was the sole common compound in condensable products; potentially formed by the β-scission debromination reaction from the parental molecular skeleton. Inorganic compounds and methane were the major constituents in the gaseous products. The pyrochar analyses confirmed the presence of metal bromides retained in the residue, averting the bromine release into the atmosphere. The ion chromatography analysis portrayed <8% of HBr gas release into the atmosphere upon pyrolysis with ZnO. The ZnO dominance herein envisaged further probes into other spinel ferrites in combating brominated polymers.

Occurrence, spatiotemporal trends, fate, and treatment technologies for microplastics and organic contaminants in biosolids: A review

This review provides a comprehensive overview of the occurrence, fate, treatment and multi-criteria analysis of microplastics (MPs) and organic contaminants (OCs) in biosolids. A meta-analysis was complementarily analysed through the literature to map out the occurrence and fate of MPs and 10 different groups of OCs. The data demonstrate that MPs (54.7% occurrence rate) and linear alkylbenzene sulfonate surfactants (44.2% occurrence rate) account for the highest prevalence of contaminants in biosolids. In turn, dioxin, polychlorinated biphenyls (PCBs) and phosphorus flame retardants (PFRs) have the lowest rates (<0.01%). The occurrence of several OCs (e.g., dioxin, per- and polyfluoroalkyl substances, polycyclic aromatic hydrocarbons, pharmaceutical and personal care products, ultraviolet filters, phosphate flame retardants) in Europe appear at higher rates than in Asia and the Americas. However, MP concentrations in biosolids from Australia are reported to be 10 times higher than in America and Europe, which required more measurement data for in-depth analysis. Amongst the OC groups, brominated flame retardants exhibited exceptional sorption to biosolids with partitioning coefficients (log Kd) higher than 4. To remove these contaminants from biosolids, a wide range of technologies have been developed. Our multicriteria analysis shows that anaerobic digestion is the most mature and practical. Thermal treatment is a viable option; however, it still requires additional improvements in infrastructure, legislation, and public acceptance.

Quantifying the removal of polybrominated diphenyl ethers (PBDEs) in physical, chemical, and biological sludge treatment systems

Polybrominated diphenyl ethers (PBDE) are priority contaminants historically used as flame retardants. PBDEs are known to occur in wastewater biosolids posing potential concerns with the beneficial land application of the biosolids. This study evaluated the removal of 21 congeners in nine full-scale sludge treatment systems including pelletization (P), alkaline stabilization (AS), and aerobic (AE) and anaerobic (AN) digestion. It is the first study to conduct a mass balance analysis of a broad spectrum of PBDEs during physical, chemical, and biological sludge treatment. The PBDE congener pattern in raw sludge and biosolids samples was consistent with commercial formulations. The fully brominated congener BDE-209 dominated biosolids from all sites with an average concentration of 620 ng/g dry weight (dw), followed by BDE-99 (173 ng/g dw) and BDE-47 (162 ng/g dw). Mass balance analysis on the P and AS processes showed no change in PBDE mass flows with treatment. However, aerobic and anaerobic digestion processes reported significant levels of removal and formation of individual congeners, though the results were not consistent between facilities. One aerobic digestion process (AE2) reported an overall average removal of 48%, whereas the other (AE1) reported very high levels of accumulation of tri- and tetraBDE congeners. Similarly, there were significant variations in PBDE behavior across the five anaerobic digestion plants studied. The plant with the longest solids retention time (SRT) (AN1) reported a moderate removal (50%) of overall PBDE loading and lower congeners, whereas other plants (AN2-AN5) showed significant low (-19%) to high (-166%) levels of formation of lower congeners. The results suggest that reduced SRTs result in formation of lower congeners while extended SRTs can lead to moderate removal of some PBDEs. Conventional sludge treatment result in low to moderate PBDE removal and advanced thermal conversion technologies may be needed to improve the contaminant removal during sludge treatment.

Per- and polyfluoroalkyl substances (PFAS) in Canadian municipal wastewater and biosolids: Recent patterns and time trends 2009 to 2021

The concentrations of per- and polyfluoroalkyl substances (PFAS) were determined in raw influent, final effluent, and treated biosolids at Canadian wastewater treatment plants (WWTPs) to evaluate the fate of PFAS through liquid and solids trains of typical treatment process types used in Canada and to assess time trends of PFAS in wastewater between 2009 and 2021. Data for 42 PFAS in samples collected from 27 WWTP across Canada were used to assess current concentrations and 48 WWTPs were included in the time trends analysis. Although regulated and phased-out of production by industry since the early 2000s and late 2000s/early2010s, respectively, perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and other long-chain PFAS continue to be widely detected in Canadian wastewater and biosolids. Short-chain PFAS that are not currently regulated in Canada were also widely detected. In general, elevated concentrations of several PFAS were observed at WWTPs that receive landfill leachate. Except for PFOS, concentrations of long-chain perfluoroalkyl carboxylates (PFCAs) and perfluoroalkane sulfonates (PFSAs) generally decreased over time in influent, effluent, and biosolids, which is attributable to industrial production phase-outs and regulations. Concentrations of PFOS did not decrease over time in wastewater media. This indicates that regulatory action and industrial phase-outs of PFOS are slow to be reflected in wastewater. Concentrations of short-chain PFCAs in wastewater influent and effluent consistently increased between 2009 and 2021, which reflect the use of short-chain PFAS as replacements for phased-out and regulated longer-chained PFAS. Short-chain PFAS were infrequently detected in biosolids. Continued periodic monitoring of PFAS in wastewater matrices in Canada and throughout the world is recommended to track the effectiveness of regulatory actions, particularly activities to address the broad class of PFAS.

The occurrence, spatial distribution, and well-depth dependence of PFASs in groundwater from a reclaimed water irrigation area

With the growing development of modern agriculture and industry, groundwater is facing more and more complex contaminants. One such contaminant is per- and polyfluoroalkyl substances (PFASs), which pose a potential risk to human health, particularly for those who rely on groundwater as their primary source of drinking water. In this study, we conducted a comprehensive investigation on the occurrence, spatial distribution, and source apportionment of PFASs in shallow (<60 m) and deep (>80 m) groundwater samples from a reclaimed water irrigation area in Beijing's suburbs. Our results showed that the average total PFAS concentration (∑10PFAS) for all samples was 10.55 ± 7.77 ng/L, ranging from 1.05 to 34.28 ng/L. The dominant congeners were PFBA, PFOA, and PFBS. No significant linear relationship was observed between PFAS concentrations and the well depth. However, the averaged ΣPFASs in groundwater were highest in the uppermost layer and declined sharply to a few ng/L in the deep aquifer below 80 m. PFASs showed elevated concentration in shallow aquifers in 9 out of 11 paired wells, indicating an overall descending trend of PFASs with increasing aquifer depth. The spatial distribution of PFASs was highly heterogeneous and showed different patterns in shallow and deep groundwater, which may be related to the complicated attenuation behavior of PFAS compounds when they transport and diffuse through overlapping aquifer layers. The influence of the landfill on groundwater PFASs was most pronounced within a 5 km radius. Source apportionment results indicated that reclaimed water irrigation is the main non-point source of PFASs in shallow groundwater. In contrast, deep groundwater is primarily subject to point sources and lateral recharge flow. This investigation of PFASs in shallow and deep wells provides a foundation for further exploration of PFASs transportation and risk prevention in regions where groundwater is a major water resource for domestic and industrial development.

Quantification and characterization of PFASs in suspended particulate matter (SPM) of German rivers using EOF, dTOPA, (non-)target HRMS

In this study, we compare analytical methods for PFAS determination-target analysis, non-target screening (NTS), direct total oxidizable precursor assay (dTOPA) and extractable organically bound fluorine (EOF). Therefore, suspended particulate matter (SPM) samples from German rivers at different locations in time series from 2005 to 2020 were analyzed to investigate temporal and spatially resolved trends. In this study 3 PFAS mass balances approaches were utilized: (i) PFAA target vs. PFAS dTOPA, (ii) PFAS target vs. EOF and (iii) PFAS target vs. PFAS dTOPA vs. organofluorines NTS vs. EOF. Mass balance approach (i) revealed high proportions of precursor substances in SPM samples. For the time resolved analysis an increase from 94% (2005) to 97% in 2019 was observable. Also for the spatial resolved analysis precursor proportions were high with >84% at all sampling sites. Mass balance approach (ii) showed that the unidentified EOF (uEOF) fraction increased over time from 82% (2005) to 99% (2019). Furthermore, along the river courses the uEOF increased. In the combined mass balance approach (iii) using 4 different analytical approaches EOF fractions were further unraveled. The EOF pattern was fully explainable at the sampling sites at Saar and Elbe rivers. For the time resolved analysis, an increased proportion of the EOF was now explainable. However, still 27% of the EOF for the time resolved analysis and 25% of the EOF for the spatial resolved analysis remained unknown. Therefore, in a complementary approach, both the EOF and dTOPA reveal unknown gaps in the PFAS mass balance and are valuable contributions to PFAS risk assessment. Further research is needed to identify organofluorines summarized in the EOF parameter.

Is PFAS from land applied municipal biosolids a significant source of human exposure via groundwater?

Per and polyfluoroakyl substances (PFAS) are emerging contaminants of critical concern commonly found in the bloodstream of most humans in the U.S. They are present in both Class A and B municipal biosolids. The potential for contamination of groundwater following land application of biosolids and subsequent leaching of PFAS through soil is one of several potential impacts that have generated discussions of possible bans on land application. In this commentary, we discuss the many factors that need to be considered to address the question: "Is PFAS from land applied biosolids a significant source of human exposure via groundwater?" The occurrence of PFAS in biosolids and biosolids-amended soils is discussed, as are the many factors that affect the potential for subsequent groundwater contamination. Additional critical factors are also noted.

Determination of Perfluorooctane Sulfonyl Fluoride and Perfluorohexane Sulfonyl Fluoride in Soil by Chemical Derivatization and Liquid Chromatography-Tandem Mass Spectrometry

Perfluorooctane sulfonyl fluoride (PFOSF) and perfluorohexane sulfonyl fluoride (PFHxSF) were listed as persistent organic pollutants by the Stockholm Convention in 2009 and 2022, respectively. To date, their concentrations in environmental samples have not been reported due to the lack of sensitive methods. Herein, a novel chemical derivatization was developed for quantitative analysis of trace PFOSF and PFHxSF in soil by derivatizing them to the corresponding perfluoroalkane sulfinic acids. The method showed good linearity in the range from 25 to 500 ng L^-1 with correlation coefficients (R²) better than 0.99. The detection limit of PFOSF in soil was 0.066 ng g^-1 with recoveries in the range of 96-111%. Meanwhile, the detection limit of PFHxSF was 0.072 ng g^-1 with recoveries in the range of 72-89%. Simultaneously, perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS) were also detected accurately without being affected by the derivative reaction. By applying this method in an abandoned fluorochemical manufacturing facility, PFOSF and PFHxSF were successfully detected at concentrations ranging from 2.7 to 357 ng g^-1 and 0.23 to 26 ng g^-1 dry weight, respectively. It is very interesting that 2 years after factory relocation, there still exists high concentrations of PFOSF and PFHxSF, which is of concern.

Recent advances in the remediation of perfluoroalkylated and polyfluoroalkylated contaminated sites

Per- and polyfluoroalkyl substances (PFASs) are compounds used since 1940 in various formulations in the industrial and consumer sectors due to their high chemical and thermal stability. In recent years, PFASs have caused global concern due to their presence in different water and soil matrices, which threatens the environment and human health. These compounds have been reported to be linked to the development of serious human diseases, including but not limited to cancer. For this reason, PFASs have been considered as persistent organic compounds (COPs) and contaminants of emerging concern (CECs). Therefore, this work aims to present the advances in remediation of PFASs-contaminated soil and water by addressing the current literature. The performance and characteristics of each technique were addressed deeply in this work. The reviewed literature found that PFASs elimination studies in soil and water were carried out at a laboratory and pilot-scale in some cases. It was found that ball milling, chemical oxidation and thermal desorption are the most efficient techniques for the removal of PFASs in soils, however, phyto-microbial remediation is under study, which claims to be a promising technique. For the remediation of PFASs-contaminated water, the processes of electrocoagulation, membrane filtration, ozofractionation, catalysis, oxidation reactions - reduction, thermolysis and destructive treatments with plasma have presented the best results. It is noteworthy that hybrid treatments have also proved to be efficient techniques in the removal of these contaminants from soil and water matrices. Therefore, the improvisation and implication of existing techniques on a field-scale are greatly warranted to corroborate the yields obtained on a pilot- and laboratory-scale.

PFASs in Soil: How They Threaten Human Health through Multiple Pathways and Whether They Are Receiving Adequate Concern

Per- and polyfluoroalkyl substances (PFASs) have been mass-produced and widely applied in consumer and industrial products, resulting in their widespread presence in the environment. Features such as environmental persistence, bioaccumulation, and high toxicity even at low doses have made PFASs an increasing concern. This brief review focuses on soil PFASs, especially the effect of soil PFASs on other environmental media and their potential threats to human health through daily diet. Specifically, soil PFASs contamination caused by different pathways was first investigated. Soil pollution from application of aqueous film-forming foams (AFFFs) is generally more severe than that from fluorochemical manufacturing plants, followed by biosolid land use, landfill, and irrigation. Factors, such as carbon chain length of PFASs, wastewater treatment technology, geographical conditions, and regional development level, are related to soil PFASs' pollution. Then, the migration, bioaccumulation, and toxicity characteristics of soil PFASs were analyzed. Short-chain PFASs have higher solubility, mobility, and bioavailability, while long-chain PFASs have higher bioaccumulation potential and are more toxic to organisms. Factors such as soil texture, solution chemistry conditions, enzymes, and fertilization conditions also influence the environmental behavior of PFASs. The risk of human exposure to PFASs through agricultural and animal products is difficult to control and varies depending on living region, age, eating habits, lifestyle, ethnicity, etc. Soil PFASs threaten drinking water safety, affect soil function, and enter food webs, threatening human health. Knowledge gaps and perspectives in these research fields are also included in current work to assist future research to effectively investigate and understand the environmental risks of soil PFASs, thereby reducing human exposure.

Impacts of Environmental and Engineered Processes on the PFAS Fingerprint of Fluorotelomer-Based AFFF

Forensic analysis can potentially be used to determine per- and polyfluoroalkyl substance (PFAS) sources at contaminated sites. However, fluorotelomer aqueous film-forming foam (AFFF) sources are difficult to identify because the polyfluorinated active ingredients do not have authentic standards and because the parent compounds can undergo transformation and differential transport, resulting in alteration of the PFAS distribution or fingerprint. In this study, we investigate changes in the PFAS fingerprint of fluorotelomer-derived AFFF due to environmental and engineered processes, including groundwater transport, surface water flow, and land application of contaminated biosolids. Fingerprint analysis supplemented by quantification of precursors and identification of suspected active ingredients shows a clear correlation between a fluorotelomer AFFF manufacturer and surface water of nearby Lake Michigan, demonstrating contamination (>100 ng/L PFOA) of the lake due to migration of an AFFF-impacted groundwater plume. In contrast, extensive processing during wastewater treatment and environmental transport results in large changes to the AFFF fingerprint near agricultural fields where contaminated biosolids were spread. At biosolids-impacted sites, the presence of active ingredients confirms contamination by fluorotelomer AFFF. While sediments can retain longer-chain PFAS, this study demonstrates that aqueous samples are most relevant for PFAS fingerprinting in complex sites, particularly where shorter-chain compounds have been used.

Assessing Potential Perfluoroalkyl Substances Trophic Transfer to Crickets (Acheta domesticus)

Although many studies have assessed the bioaccumulation of perfluoroalkyl substances (PFAS) in plant tissues, to date there has been minimal research on the bioaccumulation of PFAS in soil invertebrates that results from consuming PFAS-contaminated media. The present study focused on two different consumption pathways in a population of crickets: individuals consuming PFAS-contaminated alfalfa and individuals consuming PFAS-spiked drinking water. Alfalfa was grown in a greenhouse and irrigated with PFAS-spiked water (∼1 ppm) containing seven unique PFAS. The alfalfa was then harvested and fed to crickets. Another population of crickets was supplied with PFAS-spiked drinking water at similar concentrations to irrigation water for direct consumption. Alfalfa accumulation of PFAS and subsequent consumption by the crickets resulted in overall similar tissue concentrations in the crickets who consumed PFAS-spiked water directly. This indicates that source concentration (water) may be an important factor in assessing the bioaccumulation of PFAS in organisms. To our knowledge, ours is the first study not only to assess the direct trophic transfer of PFAS from contaminated vegetation to invertebrates, but also to highlight the similarities in bioaccumulation regardless of ingestion pathway. Environ Toxicol Chem 2022;41:2981-2992. © 2022 SETAC.

Health-related toxicity of emerging per- and polyfluoroalkyl substances: Comparison to legacy PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are highly persistent, manufactured chemicals used in various manufacturing processes and found in numerous commercial products. With over 9000 compounds belonging to this chemical class, there is increasing concern regarding human exposure to these compounds due to their persistent, bioaccumulative, and toxic nature. Human exposure to PFAS may occur from a variety of exposure sources, including, air, food, indoor dust, soil, water, from the transfer of PFAS from non-stick wrappers to food, use of cosmetics, and other personal care products. This critical review presents recent research on the health-related impacts of PFAS exposure, highlighting compounds other than Perfluorooctanoic acid (PFOA) and Perfluoroctane sulfonate (PFOS) that cause adverse health effects, updates the current state of knowledge on PFAS toxicity, and, where possible, elucidates cause-and-effect relationships. Recent reviews identified that exposure to PFAS was associated with adverse health impacts on female and male fertility, metabolism in pregnancy, endocrine function including pancreatic dysfunction and risk of developing Type 2 diabetes, lipid metabolism and risk of childhood adiposity, hepatic and renal function, immune function, cardiovascular health (atherosclerosis), bone health including risk for dental cavities, osteoporosis, and vitamin D deficiency, neurological function, and risk of developing breast cancer. However, while cause-and-effect relationships for many of these outcomes were not able to be clearly elucidated, it was identified that 1) the evidence derived from both animal models and humans suggested that PFAS may exert harmful impacts on both animals and humans, however extrapolating data from animal to human studies was complicated due to differences in exposure/elimination kinetics, 2) PFAS precursor kinetics and toxicity mechanism data are still limited despite ongoing exposures, and 3) studies in humans, which provide contrasting results require further investigation of the long-term-exposed population to better evaluate the biological toxicity of chronic exposure to PFAS.

The development of diffusive equilibrium, high-resolution passive samplers to measure perfluoroalkyl substances (PFAS) in groundwater

Per- and poly-fluoroalkyl substances (PFAS) are a group of anthropogenic, highly recalcitrant organic compounds consisting of thousands of individual species that are of increasing importance as groundwater contaminants. In-situ measurements of PFAS would be useful to better understand vertical profiles and mobility, contamination in partially saturated media, and to reduce sampling artifacts associated with groundwater collection and analysis. Diffusive equilibrium, high-resolution passive samplers (HRPPs) can be directly driven (>10 m) in sediments or groundwater. The samplers equilibrate with porewater through diffusion across the sampler membrane, providing high spatial resolution (sample every 20 cm) porewater concentrations of dissolved species. The objective of this study was to develop an HRPP to measure PFAS in contaminated groundwater and saturated media. To achieve this objective, a screening study was conducted to demonstrate quantitative measurement of selected PFAS as well as the kinetics of uptake into a sampler using both nylon and stainless steel membranes. Utilizing the results of the screening study, a prototype sampler was demonstrated in a laboratory flow box. Over a deployment period of 28 days, concentrations of several perfluoroalkyl carboxylic acids (PFCAs), a perfluoroalkyl sulfonate (PFSA), and a precursor PFAS reached equilibrium with porewater (sampler concentration >90 percent of porewater concentration). Application of these samplers could provide improved understanding of the behavior of PFAS in saturated or partially saturated groundwater systems and allow better assessment of fate and transport in the subsurface. Reliable subsurface site characterization will yield robust site assessments, conceptual models, and improve remediation designs as well as increase confidence in post remedial assessments at PFAS-impacted locations.

Release of poly- and perfluoroalkyl substances from finished biosolids in soil mesocosms

Finished biosolids were collected and characterized from seven municipal water resource recovery facilities. Poly- and perfluoroalkyl substances (PFAS) for the 54 quantified in the biosolids ranged from 323 ± 14.1 to 1100 ± 43.8 µg/kg (dry weight basis). For all biosolids, greater than 75% of the PFAS fluorine mass was associated with precursors. Di-substituted polyfluorinated phosphate esters (diPAPs) were the most abundant PFAS identified in the biosolids. The total oxidizable precursor assay on biosolids extracts generally failed to quantify the amount of precursors present, in large part due to the fact that diPAPS were not fully transformed during the TOP assay. Outdoor biosolids column leaching experiments intended to simulate biosolids land application showed sustained PFAS leaching over the 6-month study duration. Perfluoroalkyl acid (PFAA) concentrations in leachate, when detected, typically ranged in the 10 s to 100 s of ng/L; no diPAPs were detected in the leachate. The PFAA leaching from the biosolids exceeded the PFAA mass initially present in the biosolids (typically by greater than an order of magnitude), but the cumulative PFAA mass leached did not exceed the molar equivalents that could be explained by transformation of quantified precursors. These results highlight the importance of PFAA precursors initially present in biosolids and their contribution to long term leaching of PFAAs from land-applied biosolids.

Key factors controlling colloids-bulk soil distribution of polybrominated diphenyl ethers (PBDEs) at an e-waste recycling site: Implications for PBDE mobility in subsurface environment

Accumulation of polybrominated diphenyl ethers (PBDEs) in surface soils at elevated concentrations is common at e-waste recycling sites. Even though highly insoluble, migration of PBDEs into the vadose zone and groundwater is possible, due to their association with soil colloids. Here, we show that upon equilibration with artificial rainwater surface and subsurface soil samples collected at an e-waste recycling site release significant quantities of colloids, with the total concentrations of 14 PBDE congeners as high as 990 ng/g dw. The concentrations of different congeners vary markedly in the colloids, and that of BDE-209 is the highest in all the samples. Notably, even the colloids released from the soil collected at a depth of 95-105 cm contain high concentrations of PBDEs. Preferential binding of PBDEs to soil colloids is observed, with the colloids-soil distribution coefficients above 10 in certain cases. The extent of preferential binding displays no apparent correlation with the relative hydrophobicity of the PBDEs, nor can it be explained simply by considering the higher specific surface area, pore volume, and clay content of the soil colloids than the respective bulk soil. Principal component analysis shows that multiple soil properties are collectively responsible for the preferential distribution of PBDEs. Specifically, the differences in pore volume, soil organic carbon content, and pore size between colloids and soils are likely the major factors affecting the distribution of high-concentration PBDEs, whereas the differences in clay content, pore volume and specific surface area are the key factors affecting the distribution of low-concentration PBDEs. The findings clearly show that colloids are an important medium with which PBDEs are associated at contaminated sites, and underline the need of understanding colloid-facilitated transport of PBDEs at e-waste sites.

PFAS in soil and groundwater following historical land application of biosolids

The land application of digested sewage sludge (biosolids) is widely employed across the globe. Studies show that biosolids contain significant amounts of inorganic and organic materials, as well as emerging pollutants, including per- and polyfluorinated alkyl substances (PFAS). With the wide range of pollutants commonly reported in biosolids, the potential risks associated with long-term land application operations are concerning. In this study, PFAS in surface soils, deeper soils into the vadose zone, and immediately-underlying groundwater was measured at an agricultural station with a long record of biosolids applications plus irrigation using treated wastewater. Twelve PFAS homologues were detected in every near surface soil sampled 0-30 cm depth below ground surface with multiple PFAS (especially short-chain) distributed through the soil profile. Average measured concentrations of PFAS in these soils suggest the soil burden PFOS>PFDA>PFOA for all substations sampled, independent of the historical loading rates and patterns of agricultural operations on those substations. Measured concentrations of PFOA and PFOS in the soil profile (0-90 cm) suggest these compounds have migrated to deeper soil depths (up to 9 m below the surface) with quantifiable concentrations in the soil and the immediate underlying groundwater located approximately 17 m below. Estimates of the total mass of PFAS in surface soils were effectively made using PFAS levels reported in sludges from the USEPA NSSS combined with long-term loading rates on record at the substations. With the land application of biosolids in the USA regulated by the USEPA, additional and updated risk assessments and surveys to include emerging pollutants such as PFAS are needed to protect public health and the environment.

PFAS Molecules: A Major Concern for the Human Health and the Environment

Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.

Perfluorooctanoic Acid Transport in Soil and Absorption and Distribution in Alfalfa (Medicago sativa)

ABSTRACT

Perfluorooctanoic acid (PFOA) is used as a surfactant in consumer and industrial products and is frequently found in biosolids from wastewater treatment plants. When present in biosolids applied to croplands, PFOA can contaminate feed and fodder used by livestock, but the extent of PFOA transfer from soil to plants is not well characterized. A single dose of radiocarbon (14C)-tagged PFOA was applied to unplanted soil or soil containing growing alfalfa. PFOA transport through unplanted soil and uptake by alfalfa was monitored over a 10-week study period. Radiocarbon was initially measured in roots, stems, and leaves 7 days after [14C]-PFOA application to soil. PFOA accumulation was greatest in leaves during the 10-week sampling. By week 10, PFOA migration through unplanted soil had reached a depth of 22.8 ± 2.5 cm. In contrast, PFOA migrated to 7.5 ± 2.5 cm in soil containing alfalfa plants. The greatest predictor of PFOA concentration in alfalfa leaves was PFOA concentration in the top 5 cm of soil; PFOA concentrations at lower depths were not correlated with alfalfa PFOA concentrations. PFOA transport through soil may be slowed by the presence of forage; however, PFOA accumulation in edible portions of forage plants may increase food animal exposure to PFOA residues.

HIGHLIGHTS

Release, transformation, and risk factors of polybrominated diphenyl ethers from landfills to the surrounding environments: A review

Polybrominated diphenyl ethers (PBDEs) serve as brominated flame retardants when added to various products. When these products reach their end of life, a large amount of domestic waste containing PBDEs enters the landfills. Given their weak chemical bonds, they are easily affected by physical, chemical, and biological processes. These processes result in their release and the subsequent contamination of the surrounding soil, groundwater, and atmosphere, causing harm to humans and ecosystems. However, despite the progress made in the research of PBDEs over the years, understanding of the environmental behavior and fate of pollutants is still limited. With the development of cities, the release of PBDEs in old landfills will gradually increase the risk to the surrounding environment. Here we review the biological and nonbiological transformation of PBDEs and their derivatives in landfills and surrounding areas, as well as their distribution in soil, groundwater, and atmosphere. Specifically, this review aims to provide insights into the following aspects: 1) the biological (plant, animal, and microbial) and nonbiological (metal catalysis and photodegradation) conversion of PBDEs and their derivatives in landfills and surrounding areas; 2) the distribution of landfill-sourced PBDEs in the soil, groundwater, atmosphere and cross-media migration; and 3) suggestions and future research directions for the management and control of PBDEs in landfills.

Distribution, behaviour, bioavailability and remediation of poly- and per-fluoroalkyl substances (PFAS) in solid biowastes and biowaste-treated soil

Aqueous film-forming foam, used in firefighting, and biowastes, including biosolids, animal and poultry manures, and composts, provide a major source of poly- and perfluoroalkyl substances (PFAS) input to soil. Large amounts of biowastes are added to soil as a source of nutrients and carbon. They also are added as soil amendments to improve soil health and crop productivity. Plant uptake of PFAS through soil application of biowastes is a pathway for animal and human exposure to PFAS. The complexity of PFAS mixtures, and their chemical and thermal stability, make remediation of PFAS in both solid and aqueous matrices challenging. Remediation of PFAS in biowastes, as well as soils treated with these biowastes, can be achieved through preventing and decreasing the concentration of PFAS in biowaste sources (i.e., prevention through source control), mobilization of PFAS in contaminated soil and subsequent removal through leaching (i.e., soil washing) and plant uptake (i.e., phytoremediation), sorption of PFAS, thereby decreasing their mobility and bioavailability (i.e., immobilization), and complete removal through thermal and chemical oxidation (i.e., destruction). In this review, the distribution, bioavailability, and remediation of PFAS in soil receiving solid biowastes, which include biosolids, composts, and manure, are presented.

Emerging Brominated Flame Retardants 2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and Bis(2-ethylhexyl)-tetrabromophthalate (BEH-TEBP) in Chinese Food and Their Health Implications

2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP) have been frequently detected in the environment, whereas studies in food are scare. The European Food Safety Authority has requested data for their risk assessment. Herein, dietary exposure and hazard quotient (HQ) were studied based on the 5th (2009-2012) and 6th (2015-2018) Chinese total diet studies (TDSs). EHTBB was found in 61.1 and 75.9% of the two TDS sample sets, respectively. The concentrations of EHTBB in animal-derived food were higher than those in plant-derived food. The estimated daily intakes (EDIs) were 1.33 and 0.97 ng/kg bw/day, and vegetables contributed to 48.5 and 39.2% of the EDIs based on the 5th and 6th TDS, respectively. The dietary exposure to EHTBB was similar to that to hexabromocyclododecane, brominated diphenyl ether-209, and tetrabromobisphenol A (TBBPA). The HQ for EHTBB was similar to that for decabromodiphenyl ethane and surpassed that for TBBPA. Therefore, EHTBB warrants further study in food.

Fate and transport of per- and polyfluoroalkyl substances (PFASs) in the vadose zone

Per- and polyfluoroalkyl substances (PFASs) are a heterogeneous group of persistent organic pollutants that have been detected in various environmental compartments around the globe. Emerging research has revealed the preferential accumulation of PFASs in shallow soil horizons, particularly at sites impacted by firefighting activities, agricultural applications, and atmospheric deposition. Once in the vadose zone, PFASs can sorb to soil, accumulate at interfaces, become volatilized, be taken up in biota, or leach to the underlying aquifer. At the same time, polyfluorinated precursor species may transform into highly recalcitrant perfluoroalkyl acids, changing their chemical identity and thus transport behavior along the way. In this review, we critically discuss the current state of the knowledge and aim to interconnect the complex processes that control the fate and transport of PFASs in the vadose zone. Furthermore, we identify key challenges and future research needs. Consequently, this review may serve as an interdisciplinary guide for the risk assessment and management of PFAS-contaminated sites.

Organic farming: Does it contribute to contaminant-free produce and ensure food safety?

Organic farming for higher ecological and human health benefits has been adopted in about 186 countries, covering a total area of 71.5 Mha worldwide. Because of the associated practices, the flows of several environmental pollutants into the organic products threaten food safety and human health. The contaminants that occur at higher concentrations in organic produce include persistent organic pollutants (61.3-436.9 ng g^-1 lamb meat, and 0.28 pg g^-1-2.75 ng g^-1 bovine meat), heavy metals (0.5-33.0 mg kg^-1 lettuce), organochlorine pesticides (11-199 μg g^-1 carrots), cyclodienes, hexachlorocyclohexanes, hexabromocyclododecane (2-3 times higher than in conventionally produced porcine meat), hexachlorobenzene (1.38-14.49 ng g^-1 fat in milk), and non-brominated flame retardants (1.3-3.2 times higher than in conventional produce of greenhouse-grown tomato and cucumber). Moreover, some pollutants like per- and polyfluoroalkyl substances with a longer half-life (1.50-9.10 yrs) are reported to occur in several organic products. In fact, several legacy persistent organic pollutants are known for their significant trophic magnification in an urban terrestrial ecosystem. In addition, many plant functionalities are adversely affected in organic farming. Therefore, the long-term usage of organic products containing such pollutants poses a significant threat to human health. The major limitation in organic livestock production is the severe shortage of organic feed. Several variable standards and technical regulations set by the government and private agencies are the major obstacles in the global marketing of organic products. The present review critically addresses the impact of organic farming on hidden risks due to the use of composts as the amendment resources that enhance the phytoaccumulation and trophic transfer of pollutants, the functional diversity of the ecosystems, and poor harmonization among the policies and regulations in different countries for organic farming. The future directions of research have been suggested to mitigate unintended flows of pollutants into the organic products.

Insights into the Occurrence, Fate, and Impacts of Halogenated Flame Retardants in Municipal Wastewater Treatment Plants

Halogenated flame retardants (HFRs) have been extensively used in various consumer products and many are classified as persistent organic pollutants due to their resistance to degradation, bioaccumulation potential and toxicity. HFRs have been widely detected in the municipal wastewater and wastewater treatment solids in wastewater treatment plants (WWTPs), the discharge and agricultural application of which represent a primary source of environmental HFRs contamination. This review seeks to provide a current overview on the occurrence, fate, and impacts of HFRs in WWTPs around the globe. We first summarize studies recording the occurrence of representative HFRs in wastewater and wastewater treatment solids, revealing temporal and geographical trends in HFRs distribution. Then, the efficiency and mechanism of HFRs removal by biosorption, which is known to be the primary process for HFRs removal from wastewater, during biological wastewater treatment processes, are discussed. Transformation of HFRs via abiotic and biotic processes in laboratory tests and full-scale WWTPs is reviewed with particular emphasis on the transformation pathways and functional microorganisms responsible for HFRs biotransformation. Finally, the potential impacts of HFRs on reactor performance (i.e., nitrogen removal and methanogenesis) and microbiome in bioreactors are discussed. This review aims to advance our understanding of the fate and impacts of HFRs in WWTPs and shed light on important questions warranting further investigation.

Brominated flame retardants and organochlorine pesticides and incidence of uterine leiomyomata: A prospective ultrasound study

Uterine leiomyomata (UL) are hormone-responsive benign neoplasms. Brominated flame retardants and organochlorine pesticides (OCPs) can disrupt hormones involved in UL etiology.

METHODS

The Study of Environmental, Lifestyle, and Fibroids is a Detroit-area prospective cohort of 1693 Black women 23-35 years of age. At baseline and approximately every 20 months for 5 years, women completed questionnaires and underwent transvaginal ultrasounds. Using a case-cohort study design, we selected 729 UL-free participants at baseline and analyzed baseline plasma samples for polybrominated diphenyl ethers (PBDEs), a polybrominated biphenyl ether (PBB-153), and OCPs. We used Cox proportional hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Compared with total PBDE plasma concentrations <50th percentile, adjusted HRs for the 50th-74th, 75th-89th, and ≥90th percentiles were 1.00 (95% CI = 0.68, 1.47), 1.04 (95% CI = 0.63, 1.68), and 0.85 (95% CI = 0.48, 1.50), respectively. HRs for PBB-153 plasma concentrations were generally similar to total PBDE plasma concentrations. Compared with total OCP plasma concentrations <50th percentile, HRs for the 50th-74th, 75th-89th, and ≥90th percentiles were 0.86 (95% CI = 0.57, 1.29), 0.73 (95% CI = 0.43, 1.22), and 0.58 (95% CI = 0.32, 1.04), respectively. HRs for individual PBDEs and OCPs were similar to their respective totals.

CONCLUSION

We found little support for an association between brominated flame retardant plasma concentrations and UL incidence, and some evidence of lower UL incidence with the highest OCP plasma concentrations.

Removal and formation of perfluoroalkyl substances in Canadian sludge treatment systems - A mass balance approach

Poly- and per-fluoroalkyl substances (PFAS) are an emerging class of anthropogenic contaminants whose occurrence has raised concerns with the beneficial reuse of biosolids from wastewater treatment. This study evaluated the behavior of thirteen PFAS in nine Canadian sludge treatment systems including pelletization, alkaline stabilization, aerobic and anaerobic digestion processes. The composition of the overall PFAS-fluorine (ΣPFAS-F) loading in a system fed with only primary sludge was dominated by perfluorodecanoate (PFDA), whereas systems with blended primary and waste activated sludge feeds had a mix of short and long chain PFAS in raw sludges and treated biosolids. An increase in average ΣPFAS-F mass flow was observed through pelletization (19% formation) and alkaline stabilization (99% formation) processes indicating negative removal or contaminant formation. One of the two aerobic digestion systems and three of the five anaerobic digestion systems showed modest reductions (< 40% removal) in ΣPFAS-F loading. Long chain PFAS such as perfluorodecanoate (PFDA) and perfluorooctane sulfonate (PFOS) exhibited a wide variation in behavior ranging from substantial formation (> 75% formation) to modest removal (42% removal) in the surveyed systems while short chain perfluoropentanoate (PFPeA) mass flows increased through the three systems where they occurred. Overall, the contaminant mass balances revealed that there were significant changes in mass flows of the target PFAS through all kinds of sludge treatment systems. The results of this study on PFAS fate through sludge processing can inform future global PFAS risk management activities as well as sludge treatment considerations.

Uptake and accumulation of per- and polyfluoroalkyl substances in plants

Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic contaminants that are ubiquitous in the environment and have been found to be accumulated in agricultural products. Consumption of PFAS-contaminated agricultural products represents a feasible pathway for the trophic transfer of these toxic chemicals along food chains/webs, leading to risks associated with human and animal health. Recently, studies on plant uptake and accumulation of PFASs have rapidly increased; consequently, a review to summarize the current knowledge and highlight future research is needed. Analysis of the publications indicates that a large variety of plant species can take up PFASs from the environment. Vegetables and grains are the most commonly investigated crops, with perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as the most studied PFASs. The potential sources of PFASs for plant uptake include industrial emissions, irrigation with contaminated water, land application of biosolids, leachates from landfill sites, and pesticide application. Root uptake is the predominant pathway for the accumulation of PFASs in agricultural crops, and uptake by plant aboveground portions from the ambient atmosphere could play a minor role in the overall PFAS accumulation. PFAS uptake by plants is influenced by physicochemical properties of compounds (e.g., perfluorocarbon chain length, head group functionality, water solubility, and volatility), plant physiology (e.g., transpiration rate, lipid and protein content), and abiotic factors (e.g., soil organic matters, pH, salinity, and temperature). Based on literature analysis, the current knowledge gaps are identified, and future research prospects are suggested.

Aluminum hydroxide colloid facilitated transport of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in porous media

In this study, aluminum hydroxide colloids, which widely exist in soils, were selected to investigate their effect on the infiltration of an abundant congener of PBDEs (BDE-47) to groundwater. The batch and column experiments were conducted to study the co-migration of aluminum hydroxide colloid and BDE-47 in two sand media with particle sizes of 2-4.75 and 0.15 mm. The results indicated that the colloid significantly increased the transport of BDE-47 to 24.32% and 65.84% in the vadose zone of coarse and fine sand columns, respectively. The adsorption and blocking effect were found to be the two main functions during the co-migration of aluminum hydroxide colloids with BDE-47. Specifically, BDE-47 that adsorbed on colloids moved faster in the coarse porous media, and the breakthrough peak of BDE-47 appeared early in the media at an approximate pore volume of 0.15. In comparison, colloids that adsorbed onto the fine porous media formed a layer that blocked the adsorption of BDE-47 onto the fine porous media. This weakened the protection capacity of the vadose zone and led to a greater than 80% amount of BDE-47 breakthrough to the vadose zone.

PFAS concentrations in soils: Background levels versus contaminated sites

Per- and polyfluoroalkyl substances (PFAS) are contaminants of critical concern due to their persistence, widespread distribution in the environment, and potential human-health impacts. In this work, published studies of PFAS concentrations in soils were compiled from the literature. These data were combined with results obtained from a large curated database of PFAS soil concentrations for contaminated sites. In aggregate, the compiled data set comprises >30,000 samples collected from >2500 sites distributed throughout the world. Data were collected for three types of sites- background sites, primary-source sites (fire-training areas, manufacturing plants), and secondary-source sites (biosolids application, irrigation water use). The aggregated soil-survey reports comprise samples collected from all continents, and from a large variety of locations in both urban and rural regions. PFAS were present in soil at almost every site tested. Low but measurable concentrations were observed even in remote regions far from potential PFOS sources. Concentrations reported for PFAS-contaminated sites were generally orders-of-magnitude greater than background levels, particularly for PFOS. Maximum reported PFOS concentrations ranged upwards of several hundred mg/kg. Analysis of depth profiles indicates significant retention of PFAS in the vadose zone over decadal timeframes and the occurrence of leaching to groundwater. It is noteworthy that soil concentrations reported for PFAS at contaminated sites are often orders-of-magnitude higher than typical groundwater concentrations. The results of this study demonstrate that PFAS are present in soils across the globe, and indicate that soil is a significant reservoir for PFAS. A critical question of concern is the long-term migration potential to surface water, groundwater, and the atmosphere. This warrants increased focus on the transport and fate behavior of PFAS in soil and the vadose zone, in regards to both research and site investigations.

Occurrence and mass balance of emerging brominated flame retardants in a municipal wastewater treatment plant

As a class of alternative flame retardants, "novel" brominated flame retardants (NBFRs) have been widely used in clothing, textiles, electronics, building materials, and plastics and are frequently found in environmental samples. Although the use and discharge of NBFRs are increasing all over the world, little information is available about their fates and removal in wastewater treatment plants (WWTPs). This study investigated the occurrence and behavior of 2,4,6-tribromophenyl allyl ether (ATE), 2,3-dibromopropyl tribromophenyl ether (DPTE), tetrabromo-o-chlorotoluene (TBCT), pentabromobenzyl acrylate (PBBA), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (TBPH), and decabromodiphenyl ethane (DBDPE) in a municipal WWTP in Beijing, China. Four of the NBFRs (ATE, BTBPE, TBPH, and DBDPE) were detected in all wastewater and biosolid samples. The dominant compound in both wastewater and biosolid samples was DBDPE, with concentrations in the ranges of 6.4-18 ng/L and 83-288 ng/g dry weight (dw), respectively. A mass flow analysis indicated that the overall removal efficiencies were 31±18% for ATE, 97±1.5% for DPTE, 79±11% for BTBPE, 87±5.3% for TBPH, and 93±3.3% for DBDPE, but the removal efficiency in aqueous phase only ranged from -43 (ATE) to 57% (DBDPE). The low and negative removal efficiencies of ATE were possibly due to the transformation of DPTE during the anaerobic treatment processes. Under the aerobic conditions, BTBPE, TBPH and DBDPE underwent a very slow biodegradation. A total of 68-91% of the initial mass loadings of ATE, BTBPE, TBPH and DBDPE were found in the biosolid samples, suggesting that the four NBFRs were removed mainly via sorption in the WWTP.The biosolid was a huge reservoir of target NBFRs, and effective removal of NBFRs during treatment in the WWTP is critical.

Correlates of plasma concentrations of brominated flame retardants in a cohort of U.S. Black women residing in the Detroit, Michigan metropolitan area

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) are brominated flame retardant chemicals detectable in the environment and U.S. population, and are associated with adverse health outcomes over the life course. Correlates of these organic pollutants are understudied among U.S. Black women.

METHODS

Using baseline data from a prospective cohort study of U.S. Black women aged 23-35 years from the Detroit area of Michigan (2010-2012), we examined correlates of PBDEs and PBB-153. Non-fasting blood samples were collected from 742 participants at enrollment, a subset of women selected for a case-cohort study of environmental chemicals. Data on socio-demographics, behaviors, diet, medical history, and early-life exposures were collected via self-administered questionnaires, telephone interviews, and in-person clinic visits. We fit linear regression models to calculate percent differences and 95% confidence intervals in lipid adjusted plasma concentrations of 11 individual PBDE congeners and PBB-153 for each baseline predictor.

RESULTS

In models adjusted for all other correlates, a 5-year increase in age was inversely associated with most PBDE congeners (% differences ranged from 6 to 15% lower), and was positively associated with PBB-153 (52% higher). A 5-kg/m2 increase in BMI was inversely associated with PBDE-153 and PBB-153 (16% lower for both), and 6% higher for PBDE-28. Compared with having never been breastfed in infancy, ≥3 months of breastfeeding in infancy was associated with 69% higher PBB-153 concentrations. Lower education, current smoking, and heavy alcohol use were associated with higher plasma concentrations of most flame retardants. Diet was not an important predictor.

CONCLUSION

Important correlates for elevated body burdens of PBB-153 were increasing age and a history of having been breastfed in infancy. Education, smoking, and heavy alcohol use were important predictors of elevated body burdens of most flame retardants. This study fills an important gap in the environmental health literature by focusing on an understudied population.

Per- and polyfluoroalkyl substances in commercially available biosolid-based products: The effect of treatment processes

Per- and polyfluoroalkyl substances (PFAS) have been used in a variety of consumer and industrial products and are known to accumulate in sewage sludge due to sorption and their recalcitrant nature. Treatment processes ensure safe and high-quality biosolids by reducing the potential for adverse environmental impacts such as pathogen levels; however, they have yet to be evaluated for their impact on the fate of PFAS. The objective of this study was to compare PFAS concentrations in four commercially available biosolid-based products that received different types of treatments: heat treatment, composting, blending, and thermal hydrolysis. Seventeen perfluoroalkyl acids (PFAAs) were quantified using liquid chromatography with tandem quadrupole time-of-flight mass spectrometry followed by screening for 30 PFAA precursors. Treatment processes did not reduce PFAA loads except for blending, which served only to dilute concentrations. Several PFAA precursors were identified with 6:2 and 8:2 fluorotelomer phosphate diesters in all samples pre- and post-treatment. PRACTITIONER POINTS: Heat treatment and composting increased perfluoroalkyl acid (PFAA) concentrations. Only dilution from blending with non-PFAS material decreased PFAA concentrations. Thermal hydrolysis process had no apparent effect on PFAA concentrations. PFAS sources are a greater driver of PFAS loads in biosolid-based products than treatment processes.

Brominated flame retardants in a computer technical service: Indoor air gas phase, submicron (PM1) and coarse (PM10) particles, associated inhalation exposure, and settled dust

Brominated flame retardants (BFRs) are found in multi-media indoors, therefore, may pose serious risks to human health. This study investigated the occurrence of BFRs in particulate matter (PM₁ and PM₁₀) and gas phase by active and passive sampling, and settled dust to estimate potential exposure in a computer technical service. Polybrominated diphenyl ethers (PBDEs) and their alternatives (novel BFRs, NBFRs) were studied. PM and gas phase were collected on glass fiber filters and polyurethane foam plugs, respectively, and analyzed with a GC/MS after extraction, clean-up, and concentration. Inhalation exposure of the staff was estimated based on the measured concentrations using Monte Carlo simulation. BDE-209 was the dominating PBDE congener in all media while bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate and 1,2-bis(2,4,6-tribromophenoxy)ethane were those of NBFRs. Submicron particulate matter (PM₁) BFR levels constituted about one half of the PM₁₀-associated concentrations, while average PM₁₀ mass concentration (69.9 μg m^-3) was nine times that of PM₁ (7.73 μg m^-3). Calculated log₁₀ dust-gas and PM-gas partitioning coefficients ranged from -5.03 to -2.10, -2.21 to -0.55, and -2.26 to -1.04 for settled dust, PM₁₀, and PM₁, respectively. The indoor/outdoor concentration ratios were >1 for all compounds indicating the strength of indoor sources in the service. The estimated potential inhalation exposures, for future chronic-toxic and carcinogenic risk assessments, indicated that the levels of gas-phase and PM₁-associated exposures were similar at approximately one half of PM₁₀-associated levels. Results of this study indicate that the occurrence of BFRs in all studied media should be taken into consideration for occupational health mitigation efforts.

Levels of polybrominated diphenyl ethers and hexabromocyclododecane in treatment plant sludge: Implications on sludge management

Past usage of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) in commercial products resulted in their continuous emission from sources. Wastewater treatment plants (WWTP) are the main sinks resulting from their industrial and domestic usage as well as atmospheric deposition. This preliminary study examined levels of PBDEs and HBCDD in urban and industrial WWTP sludge samples for the first time from Turkey. PBDE concentrations (sum of 26 congeners) of eight samples collected from four WWTPs were between 300 and 655 ng g^-1 dw and 67-2.5*10⁷ ng g^-1 dw, and HBCDD concentrations (sum of α-, β-, and γ- diastereoisomers) ranged 75-616 ng g^-1 dw and 13-416 ng g^-1 dw, for urban and industrial WWTP samples, respectively. Although PBDEs have never been produced in Turkey, the highest PBDE concentration in sewage sludge worldwide was identified in one of the WWTPs. PBDE and HBCDD levels in other sludge samples were comparable to those reported in the literature. Application of a chemical mass balance model (CMB) suggested: (i) the main source of PBDEs as deca-BDE mixture; (ii) influence of a background air PBDE profile for one of the industrial WWTPs, having low contamination; (iii) indoor dust PBDE contamination as another source for urban WWTPs. The preliminary results for BFR levels in Turkey were discussed in terms of sludge disposal methods used worldwide, and the need for regulatory limits for BFRs in sludge management.

Perfluorooctane sulfonate in surface soils: Effects on reproduction in the collembolan, Folsomia candida, and the oribatid mite, Oppia nitens

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant, which has been detected at significant concentrations in soils at sites used for fire-fighting training operations. Recent ecotoxicological research has mainly focused on earthworms to assess the toxicity of PFOS in soil. However, the inclusion of other soil taxonomic groups allow for a more holistic estimate of contaminant risk, including the derivation of more comprehensive soil quality guidelines. The present study assessed the toxicity of PFOS using the collembolan, Folsomia candida, and the oribatid mite, Oppia nitens, in two types of soil: a coarse-textured sandy loam (VSL) and fine-textured clay loam (NRS). As a standard O. nitens reproduction test is being formalized, the results of the study were also used to compare sensitivity across test species. Effects were soil dependent, with test species being 2-4 times more susceptible to PFOS in VSL, relative to NRS, likely due to differences in organic matter and clay content. Oppia nitens was significantly more sensitive to PFOS, regardless of soil type, in comparison to F. candida. The IC50s for reproduction for O. nitens were 23 mg kg^-1 (95% confidence interval: 17-32 mg kg^-1) in the VSL and 95 mg kg^-1 (69-134 mg kg^-1) in the NRS, and for F. candida were 94 mg kg^-1 (72-122 mg kg^-1) in the VSL and 233 mg kg^-1 (177-306 mg kg^-1) in the NRS. The present study demonstrates the application and inclusion of the oribatid mite, O. nitens, for the risk assessment of contaminants in soil.

Organic contaminants in African aquatic systems: Current knowledge, health risks, and future research directions

Organic contaminants (OCs) are increasingly being reported in African aquatic systems, yet a critical evaluation of the literature is still lacking. The objectives of this review were to: (1) identify hotspot reservoirs, transfer pathways and ecological and human risks of OCs, (2) identify potential interventions to minimize the health risks, and (3) highlight knowledge gaps and research constraints. OCs widely reported in aquatic systems include pesticides, pharmaceuticals, plasticizers, solvents, endocrine disrupting compounds, and antimicrobial resistance genes, originating from applications in crop protection, veterinary and animal husbandry, human sanitation and hygiene, human vector and disease control. Potential hotspot reservoirs of OCs include wastewaters, on-site sanitation systems, leachates from non-engineered landfills and contaminated recharge of shallow groundwater systems. OCs could be transferred into humans via drinking of contaminated water, consumption of contaminated crops and aquatic foods, and to a lesser extent, inhalation and dermal contact. Ecological effects including intersex, estrogenicity, and acute and chronic toxicity occur in avian and aquatic species. Although the evidence base of human ecotoxicological effects of OC remains weak, pesticides have been reported in human milk, serum and sperms, pointing to potential chronic and acute toxicity and endocrine disruption. The prevalence of antimicrobials and their resistance genes could in turn lead to antimicrobial resistance in humans. The lack of OC monitoring in drinking water, coupled with over-reliance on untreated drinking water vulnerable to OC contamination predisposes humans to OC health risks. Appropriate water treatment methods, were identified, and a conceptual framework developed to minimize the ecological and human health risks. Future research directions on OC hotspot reservoirs, environmental behaviour and fate, ecotoxicology, epidemiology and interventions to minimize health risks are highlighted. However, lack of advanced analytical facilities in most African countries and other developing regions will continue to constrain OC research for now and in the foreseeable future.