Persistent Organic Pollutants (POPs) and Related Chemicals in the Global Environment: Some Personal Reflections

Multiple-component covalent organic frameworks for simultaneous extraction and determination of multitarget pollutants in sea foods

Persistent organic pollutants (POPs), such as perfluoroalkyl and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and bisphenols (BPs), have been raising global concerns due to their toxic effects on environment and human health. The monitoring of residues of POPs in seafood is crucial for assessing the accumulation of these contaminants in the study area and mitigating potential risks to human health. However, the diversity and complexity of POPs in seafood present significant challenges for their simultaneous detection. Here, a novel multi-component fluoro-functionalized covalent organic framework (OH-F-COF) was designed as SPE adsorbent for simultaneous extraction POPs. On this basis, the recognition and adsorption mechanisms were investigated by molecular simulation. Due to multiple interactions and large specific surface area, OH-F-COF displayed satisfactory coextraction performance for PFASs, PCBs, and BPs. Under optimized conditions, the OH-F-COF sorbent was employed in a strategy of simultaneous extraction and stepwise elution (SESE), in combination with HPLC-MS/MS and GC-MS method, to effectively determined POPs in seafood collected from coastal areas of China. The method obtained low detection limits for BPs (0.0037 -0.0089 ng/g), PFASs (0.0038 -0.0207 ng/g), and PCBs (0.2308 -0.2499 ng/g), respectively. This approach provided new research ideas for analyzing and controlling multitarget POPs in seafood. ENVIRONMENTAL IMPLICATIONS: Persistent organic pollutants (POPs), such as perfluoroalkyl and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and bisphenols (BPs), have caused serious hazards to human health and ecosystems. Hence, there is a need to develop a quantitative method that can rapidly detect POPs in environmental and food samples. Herein, a novel multi-component fluorine-functionalized covalent organic skeletons (OH-F-COF) were prepared at room temperature, and served as adsorbent for POPs. The SESE-SPE strategy combined with chromatographic techniques was used to achieve a rapid detection of POPs in sea foods from the coastal provinces of China. This method provides a valuable tool for analyzing POPs in environmental and food samples.

Characteristics and degradation mechanisms of polychlorinated naphthalenes in surface soil in Yangtze River Delta, China

Both thermal and environmental processes are significant factors influencing the existing characteristics, e.g., congener distributions, and existing levels, of polychlorinated naphthalenes (PCNs) in the environment. Soil plays an important role in the life cycle of PCNs, but degradation of PCNs in soils has never been reported. In this study, we collected surface soil samples from 13 cities in the Yangtze River Delta, which is one of the most crowded areas of China and analyzed the samples for 75 PCNs. The long-range transportation from polluted areas was the major source for PCNs in remote areas, but the PCN profiles in remote areas reported in our previous studies were different from those in human settlement in this study, indicating there is a transformation of PCNs after emissions from anthropogenic activities. Two experiments were then designed to reveal the degradation mechanisms, including influencing factors, products, and pathways, of PCNs in surface soils. Based on the experiments, we found that the major factor driving the losses of PCNs in surface soils was volatilization, followed by photo irradiation and microbial metabolism. Under photo-irradiation, the PCN structures would be destroyed through a process of dechlorination followed by oxidation. In addition, the dechlorination pathways of PCNs have been established and found to be significantly influenced by the structure-related parameters.

Presence of polycyclic aromatic hydrocarbons and persistent organochlorine pollutants in human Milk: Evaluating their levels, association with Total antioxidant capacity, and risk assessment

Breastfeeding provides numerous health benefits for both infants and mothers, promoting optimal growth and development while offering protection against various illnesses and diseases. This study investigated the levels of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polycyclic aromatic hydrocarbons (PAH) in human milk sampled in Zadar (Croatia). The primary objectives were twofold: firstly, to evaluate the individual impact of each compound on the total antioxidant capacity (TAC) value, and secondly, to assess associated health risks. Notably, this study presents pioneering and preliminary insights into PAH levels in Croatian human milk, contributing to the limited research on PAH in breast milk worldwide. PCB and OCP levels in Croatian human milk were found to be relatively lower compared to worldwide data. Conversely, PAH levels were comparatively higher, albeit with lower detection frequencies. A negative correlation was established between organic contaminant levels and antioxidative capacity, suggesting a potential link between higher antioxidative potential and lower organic contaminant levels. Diagnostic ratio pointed towards traffic emissions as the primary source of the detected PAH. The presence of PAH suggests potential health risk, underscoring the need for further in-depth investigation.

Prioritization of organic contaminants in China's groundwater based on national-scale monitoring data and their persistence, bioaccumulation, and toxicity

There has been increasing concern regarding the adverse environmental and health effects of organic pollutants. A list of priority control organic pollutants (PCOPs) can provide regulatory frameworks for the use and monitoring of organic compounds in the environment. In this study, 20,010 groundwater samples were collected from 15 "first level" groundwater resource zones in China. Fifty (50) organic compounds were analyzed based on their prevalence, occurrence, and physicochemical properties (persistence, bioaccumulation, and toxicity). Results showed that 16 PCOPs, including 12 pesticides, 3 aromatic hydrocarbons (AHs), and 1 phthalate ester, were recognized. Pesticides and AHs accounted for 75 % and 18.75 % of the high-priority pollutants, respectively. There were significant differences in PCOPs between confined and phreatic groundwater. Higher concentrations of pesticides were mainly detected in phreatic groundwater. PCOPs detected in samples from the 15 groundwater resource zones were mainly pesticides and AHs. The groundwater data indicate that the organic compounds detected in the Yellow River Basin (YRB), Yangtze River Basin (YZB), Liaohe River Basin (LRB), and Songhua River Basin (SRB) are mainly categorized as Q1 (high priority) and Q2 (medium priority) pollutants based on the contaminants ranking system in China. The findings from this study offer a snapshot of the wide distribution of PCOPs in the surveyed regions, and are expected to establishing treatment and prevention measures at both the regional and national levels in China.

Atomically dispersed copper-zinc dual sites anchored on nitrogen-doped porous carbon toward peroxymonosulfate activation for degradation of various organic contaminants

Single-atom catalysts (SACs) have been widely studied in Fenton-like reactions, wherein their catalytic performance could be further enhanced by adjusting electronic structure and regulating coordination environment, although relevant research is rarely reported. This text elucidates fabrication of dual atom catalyst systems aimed at augmenting their catalytic efficiency. Herein, atomically dispersed copper-zinc (Cu-Zn) dual sites anchored on nitrogen (N)-doped porous carbon (NC), referred to as CuZn-NC, were synthesized using cage-encapsulated pyrolysis and host-guest strategies. The CuZn-NC catalyst exhibited high activity in activation of peroxymonosulfate (PMS) for degradation of organic pollutants. Based on synergistic effects of adjacent Cu and Zn atom pairs, CuZn-NC (PMS) system achieved 94.44 % bisphenol A (BPA) degradation in 24 min. The radical pathway predominated, and coexistence of non-radical species was demonstrated for BPA degradation in CuZn-NC/PMS system. More importantly, CuZn-NC/PMS system showed generality for degradation of various refractory contaminants. Our experiments indicate that CuZn-N sites on CuZn-NC act as active sites for bonding PMS molecules with optimal binding energy, while pyrrolic N sites are considered as adsorption sites for organic molecules. Overall, this research designs diatomic site catalysts (DACs), with promising implications for wastewater treatment.

The role and mechanisms of microbes in dichlorodiphenyltrichloroethane (DDT) and its residues bioremediation

Environmental contamination with dichlorodiphenyltrichloroethane (DDT) has sever effects on the ecosystem worldwide. DDT is a recalcitrant synthetic chemical with high toxicity and lipophilicity. It is also bioaccumulated in the food chain and causes genotoxic, estrogenic, carcinogenic, and mutagenic effects on aquatic organisms and humans. Microbial remediation mechanism and its enzymes are very important for removing DDT from environment. DDT and its main residues dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) can biodegrade slowly in soil and water. To enhance this process, a number of strategies are proposed, such as bio-attenuation, biostimulation, bioaugmentation and the manipulation of environmental conditions to enhance the activity of microbial enzymes. The addition of organic matter and flooding of the soil enhance DDT degradation. Microbial candidates for DDT remediation include micro-algae, fungi and bacteria. This review provide brief information and recommendation on microbial DDT remediation and its mechanisms.

Profiling population-wide exposure to environmental chemicals: A case study of naphthalene

Long-term exposure to environmental chemicals can detrimentally impact human health, and understanding the relationship between age distribution and levels of external and internal exposure is crucial. Nonetheless, existing methods for assessing population-wide exposure across age groups are limited. To bridge this research gap, we introduced a modeling approach designed to assess both chronic external and internal exposure to chemicals at the population level. The external and internal exposure assessments were quantified in terms of the average daily dose (ADD) and steady-state blood concentration of the environmental chemical, respectively, which were categorized by age and gender groups. The modeling process was presented within a spreadsheet framework, affording users the capability to execute population-wide exposure analyses across a spectrum of chemicals. Our simulation outcomes underscored a salient trend: younger age groups, particularly infants and children, exhibited markedly higher ADD values and blood concentrations of environmental chemicals compared to their older counterparts. This observation is due to the elevated basal metabolic rate per unit of body weight characteristic of younger individuals, coupled with their diminished biotransformation kinetics of xenobiotics within their livers. These factors collectively contribute to increased intake rates of environmental chemicals per unit of body weight through air and food consumption, along with heightened bioaccumulation of these chemicals within their bodies (e.g., blood). Furthermore, we augmented the precision of the external and internal exposure assessment by incorporating the age distribution across the population. The simulation outcomes unveiled that, to estimate the central tendency of the population's exposure levels, employing the baseline value group (age group 21-30) or the surrogate age of 25 serves as a simple yet dependable approach. However, for comprehensive population protection, our recommendation aligns with conducting exposure assessments for the younger age groups (age group 0-11). Future studies should integrate individual-level exposure assessment, analyze vulnerable population groups, and refine population structures within our developed model.

Characterizing the regional distribution, interaction with microorganisms, and sources of dissolved organic matter for summer rainfall: Insights from spectroscopy, community structure, and back-trajectory analyses

Dissolved organic matter (DOM) in rainfall participates in many biogeochemical cycles in aquatic environments and affects biological activities in water bodies. Revealing the characteristics of rainfall DOM could broaden our understanding of the carbon cycle. Therefore, the distribution characteristics and response mechanisms of DOM to microorganisms were investigated in different regions of Hebei. The results indicated that the water quality of the northern region was worse than that of the middle and southern regions. The two protein like components (C1, C2) and one humic like component (C3) were obtained; at high molecular weight (MW), the fluorescence intensity is high in the northern region (0.03 ± 0.02 R.U.), while at low MW, the fluorescence intensity is highest in the southern region (0.50 ± 0.18 R.U.). Furthermore, C2 is significantly positively correlated with C1 (P < 0.01), while C2 is significantly negatively correlated with C3 (P < 0.05) was observed. The spectral index results indicated that rainfall DOM exhibited low humification and highly autochthonous characteristics. The southern region obtained higher richness and diversity of microbial species than northern region (P < 0.05). The community exhibits significant spatiotemporal differences, and the Acinetobacter, Enterobacter, and Massilia, were dominant genus. Redundancy and network analyses showed that the effects of C1, C2, and nitrate on microorganisms increased with decreasing MW, while low MW exhibited a more complex network between DOM and microorganisms than high MW. Meanwhile, C1, C2 had a large total effect on β-diversity and function through structural equation modeling. The backward trajectory model indicates that the sources of air masses are from the northwest, local area, and sea in the northern, middle, and southern regions, respectively. This study broadened the understanding of the composition of summer rainfall DOM and its interactions with microorganisms during rainfall.

Combatting multiple aromatic organohalide pollutants in sediments by bioaugmentation with a single Dehalococcoides

Dehalococcoides are capable of dehalogenating various organohalide pollutants under anaerobic conditions, and they have been applied in bioremediation. However, the presence of multiple aromatic organohalides, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and tetrabromobisphenol A (TBBPA), at contaminated sites may pose challenges to Dehalococcoides-mediated bioremediation due to the lack of knowledge about the influence of co-contamination on bioremediation. In this study, we investigated the bioremediation of aromatic organohalides present as individual and co-contaminants in sediments by bioaugmentation with a single population of Dehalococcoides. Bioaugmentation with Dehalococcoides significantly increased the dehalogenation rate of PCBs, PBDEs, and TBBPA in sediments contaminated with individual pollutants, being up to 19.7, 27.4 and 2.1 times as that in the controls not receiving bioinoculants. For sediments containing all the three classes of pollutants, bioaugmentation with Dehalococcoides also effectively enhanced dehalogenation, and the extent of enhancement depended on the bioinoculants and types of pollutants. Interestingly, in many cases co-contaminated sediments bioaugmented with Dehalococcoides mccartyi strain CG1 displayed a greater enhancement in dehalogenation rates compared to the sediments polluted with individual pollutant. For instance, when augmented with a low quantity of strain CG1, the dehalogenation rates of Aroclor1260 and PBDEs in co-contaminated sediments were approximately two times as that in sediments containing individual pollutants (0.428 and 9.03 vs. 0.195 and 4.20 × 10-3d-1). Additionally, D. mccartyi CG1 grew to higher abundances in co-contaminated sediments. These findings demonstrate that a single Dehalococcoides population can sustain dehalogenation of multiple aromatic organohalides in contaminated sediments, suggesting that co-contamination does not necessarily impede the use of Dehalococcoides for bioremediation. The study also underscores the significance of anaerobic organohalide respiration for effective bioremediation.

Soil's Hidden Power: The Stable Soil Organic Carbon Pool Controls the Burden of Persistent Organic Pollutants in Background Soils

Persistent organic pollutants (POPs) tend to accumulate in cold regions by cold condensation and global distillation. Soil organic matter is the main storage compartment for POPs in terrestrial ecosystems due to deposition and repeated air-surface exchange processes. Here, physicochemical properties and environmental factors were investigated for their role in influencing POPs accumulation in soils of the Tibetan Plateau and Antarctic and Arctic regions. The results showed that the soil burden of most POPs was closely coupled to stable mineral-associated organic carbon (MAOC). Combining the proportion of MAOC and physicochemical properties can explain much of the soil distribution characteristics of the POPs. The background levels of POPs were estimated in conjunction with the global soil database. It led to the proposition that the stable soil carbon pools are key controlling factors affecting the ultimate global distribution of POPs, so that the dynamic cycling of soil carbon acts to counteract the cold-trapping effects. In the future, soil carbon pool composition should be fully considered in a multimedia environmental model of POPs, and the risk of secondary release of POPs in soils under conditions such as climate change can be further assessed with soil organic carbon models.

A graphene oxide based composite granule for methylene blue separation from aqueous solution: Adsorption, kinetics and thermodynamic studies

Graphene oxide and chitosan composite material using as a high-efficiency and low-cost granular adsorbent for methylene blue removal was fabricated via self-assembling method. The effects of pH value, contact time, initial concentration, adsorbent dose, temperature, and recyclic stability on the adsorption performance of methylene blue in aqueous solution were investigated in detail. Desorption process with the effects of solvents, contact time, and temperature were also conducted carefully in this study. The adsorption kinetics and adsorption isotherm of dye adsorption process showed that dye adsorption process was fitted to the pseudo-second-order kinetic model and the Freundlich adsorption isotherm, indicating a physical adsorption process with multilayer adsorption. The intra-particle diffusion model indicated that the dye adsorption by the granular adsorbent was strongly happened during the first 4 h. The thermodynamic study showed that the adsorption was a spontaneous and exothermic process and dye ions were condensed onto the surface of adsorbent. The maximum adsorption capacity of dye on the granular adsorbent was calculated as 951.35 mg/g and the adsorbent could maintain its adsorption performance after six cycles. In general, this study provided an efficient, cost-effective, and recyclable the granular adsorbent for dye separation from aqueous solution.

Efficiency of clustering methods and self-organizing maps of Adriatic sardines and anchovies regarding organochlorine and fatty acid burden

The Adriatic Sea plays a crucial role as both a significant fishing ground and a thriving trading market for small pelagic edible fish. Recognized for their nutritional value, these fish are esteemed for their high protein content and abundance of polyunsaturated omega-3 and omega-6 fatty acids, making them a sought-after and healthful food choice. Nevertheless, pelagic species can also serve as a reservoir for lipophilic organochlorine pollutants, posing potential risks to human health. In this study, we compared traditional classification methods traditional principal component analysis (PCA) and Ward's clustering with an advanced self-organizing map (SOM) algorithm in determining distribution patterns of 24 organochlorines and 19 fatty acids in sardine and anchovy samples taken from the eastern Adriatic. The outcomes reveal the strengths and weaknesses of the three approaches (PCA, Ward's clustering, and SOM). However, it is evident that SOM has proven to be the most effective in offering detailed information and data visualization. Although sardines and anchovies exhibit similar distribution patterns for p,p'-DDE, PCB-28, PCB-138, PCB-153, PCB-118, and PCB-170, they differ in the concentrations of fatty acids such as stearic, palmitic, myristic, oleic, docosapentaenoic, and docosahexaenoic acid. Our findings supply valuable insights for environmental authorities and fish consumers concerning the potential risks associated with organochlorines in these two types of fish.

Unveiling the inhibitory mechanisms of chromium exposure on microbial reductive dechlorination: Kinetics and microbial responses

Chromium and organochlorine solvents, particularly trichloroethene (TCE), are pervasive co-existing contaminants in subsurface aquifers due to their extensive industrial use and improper disposal practices. In this study, we investigated the microbial dechlorination kinetics under different TCE-Cr(Ⅲ/VI) composite pollution conditions and elucidated microbial response mechanisms based on community shift patterns and metagenomic analysis. Our results revealed that the reductive dechlorinating consortium had high resistance to Cr(III) but extreme sensitivity to Cr(VI) disturbance, resulting in a persistent inhibitory effect on subsequent dechlorination. Interestingly, the vinyl chloride-respiring organohalide-respiring bacteria (OHRB) was notably more susceptible to Cr(III/VI) exposure than the trichloroethene-respiring one, possibly due to inferior competition for growth substrates, such as electron donors. In terms of synergistic non-OHRB populations, Cr(III/VI) exposure had limited impacts on lactate fermentation but significantly interfered with H2-producing acetogenesis, leading to inhibited microbial dechlorination due to electron donor deficiencies. However, this inhibition can be effectively mitigated by the amendment of exogenous H2 supply. Furthermore, being the predominant OHRB, Dehalococcoides have inherent Cr(VI) resistance defects and collaborate with synergistic non-OHRB populations to achieve concurrent bio-detoxication of Cr(VI) and TCE. Our findings expand the understanding of the response patterns of different functional populations towards Cr(III/VI) stress, and provide valuable insights for the development of in situ bioremediation strategies for sites co-contaminated with chloroethene and chromium.

Global prevalence of organohalide-respiring bacteria dechlorinating polychlorinated biphenyls in sewage sludge

BACKGROUND

Massive amounts of sewage sludge are generated during biological sewage treatment and are commonly subjected to anaerobic digestion, land application, and landfill disposal. Concurrently, persistent organic pollutants (POPs) are frequently found in sludge treatment and disposal systems, posing significant risks to both human health and wildlife. Metabolically versatile microorganisms originating from sewage sludge are inevitably introduced to sludge treatment and disposal systems, potentially affecting the fate of POPs. However, there is currently a dearth of comprehensive assessments regarding the capability of sewage sludge microbiota from geographically disparate regions to attenuate POPs and the underpinning microbiomes.

RESULTS

Here we report the global prevalence of organohalide-respiring bacteria (OHRB) known for their capacity to attenuate POPs in sewage sludge, with an occurrence frequency of ~50% in the investigated samples (605 of 1186). Subsequent laboratory tests revealed microbial reductive dechlorination of polychlorinated biphenyls (PCBs), one of the most notorious categories of POPs, in 80 out of 84 sludge microcosms via various pathways. Most chlorines were removed from the para- and meta-positions of PCBs; nevertheless, ortho-dechlorination of PCBs also occurred widely, although to lower extents. Abundances of several well-characterized OHRB genera (Dehalococcoides, Dehalogenimonas, and Dehalobacter) and uncultivated Dehalococcoidia lineages increased during incubation and were positively correlated with PCB dechlorination, suggesting their involvement in dechlorinating PCBs. The previously identified PCB reductive dehalogenase (RDase) genes pcbA4 and pcbA5 tended to coexist in most sludge microcosms, but the low ratios of these RDase genes to OHRB abundance also indicated the existence of currently undescribed RDases in sewage sludge. Microbial community analyses revealed a positive correlation between biodiversity and PCB dechlorination activity although there was an apparent threshold of community co-occurrence network complexity beyond which dechlorination activity decreased.

CONCLUSIONS

Our findings that sludge microbiota exhibited nearly ubiquitous dechlorination of PCBs indicate widespread and nonnegligible impacts of sludge microbiota on the fate of POPs in sludge treatment and disposal systems. The existence of diverse OHRB also suggests sewage sludge as an alternative source to obtain POP-attenuating consortia and calls for further exploration of OHRB populations in sewage sludge. Video Abstract.

Interspecies Mobility of Organohalide Respiration Gene Clusters Enables Genetic Bioaugmentation

Anthropogenic organohalide pollutants pose a severe threat to public health and ecosystems. In situ bioremediation using organohalide respiring bacteria (OHRB) offers an environmentally friendly and cost-efficient strategy for decontaminating organohalide-polluted sites. The genomic structures of many OHRB suggest that dehalogenation traits can be horizontally transferred among microbial populations, but their occurrence among anaerobic OHRB has not yet been demonstrated experimentally. This study isolates and characterizes a novel tetrachloroethene (PCE)-dechlorinating Sulfurospirillum sp. strain SP, distinguishing itself among anaerobic OHRB by showcasing a mechanism essential for horizontal dissemination of reductive dehalogenation capabilities within microbial populations. Its genetic characterization identifies a unique plasmid (pSULSP), harboring reductive dehalogenase and de novo corrinoid biosynthesis operons, functions critical to organohalide respiration, flanked by mobile elements. The active mobility of these elements was demonstrated through genetic analyses of spontaneously emerging nondehalogenating variants of strain SP. More importantly, bioaugmentation of nondehalogenating microcosms with pSULSP DNA triggered anaerobic PCE dechlorination in taxonomically diverse bacterial populations. Our results directly support the hypothesis that exposure to anthropogenic organohalide pollutants can drive the emergence of dehalogenating microbial populations via horizontal gene transfer and demonstrate a mechanism by which genetic bioaugmentation for remediation of organohalide pollutants could be achieved in anaerobic environments.

Sampling efficiency of a polyurethane foam air sampler: Effect of temperature

Effective monitoring of atmospheric concentrations is vital for assessing the Stockholm Convention's effectiveness on persistent organic pollutants (POPs). This task, particularly challenging in polar regions due to low air concentrations and temperature fluctuations, requires robust sampling techniques. Furthermore, the influence of temperature on the sampling efficiency of polyurethane foam discs remains unclear. Here we employ a flow-through sampling (FTS) column coupled with an active pump to collect air samples at varying temperatures. We delved into breakthrough profiles of key pollutants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and organochlorine pesticides (OCPs), and examined the temperature-dependent behaviors of the theoretical plate number (N) and breakthrough volume (VB) using frontal chromatography theory. Our findings reveal a significant relationship between temperature dependence coefficients (KTN, KTV) and compound volatility, with decreasing values as volatility increases. While distinct trends are noted for PAHs, PCBs, and OCPs in KTN, KTV values exhibit similar patterns across all chemicals. Moreover, we establish a binary linear correlation between log (VB/m3), 1/(T/K), and N, simplifying breakthrough level estimation by enabling easy conversion between N and VB. Finally, an empirical linear solvation energy relationship incorporating a temperature term is developed, yielding satisfactory results for N at various temperatures. This approach holds the potential to rectify temperature-related effects and loss rates in historical data from long-term monitoring networks, benefiting polar and remote regions.

Polychlorinated biphenyls in mussels, small pelagic fish, tuna, turtles, and dolphins from the Croatian Adriatic Sea waters: an overview of the last two decades of monitoring

This review summarises our two decades of polychlorinated biphenyl (PCB) monitoring in different marine organisms along the eastern Adriatic Sea. The aim was to gain an insight into the trends of PCB distribution in order to evaluate the effectiveness of past and current legislation and suggest further action. Here we mainly focus on PCB levels in wild and farmed Mediterranean mussels, wild and farmed bluefin tuna, loggerhead sea turtles, common bottlenose dolphins, and small pelagic fish. The use of artificial intelligence and advanced statistics enabled an insight into the influence of various variables on the uptake of PCBs in the investigated organisms as well as into their mutual dependence. Our findings suggest that PCBs in small pelagic fish and mussels reflect global pollution and that high levels in dolphins and wild tuna tissues raise particular concern, as they confirm their biomagnification up the food chain. Therefore, the ongoing PCB monitoring should focus on predatory species in particular to help us better understand PCB contamination in marine ecosystems in our efforts to protect the environment and human health.

Enantioselectivity in ecotoxicity of pharmaceuticals, illicit drugs, and industrial persistent pollutants in aquatic and terrestrial environments: A review

At present, there is a serious concern about the alarming number of recalcitrant contaminants that can negatively affect biodiversity threatening the ecological status of marine, estuarine, freshwater, and terrestrial ecosystems (e.g., agricultural soils and forests). Contaminants of emerging concern (CEC) such as pharmaceuticals (PHAR), illicit drugs (ID), industrial persistent pollutants, such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and chiral ionic solvents are globally spread and potentially toxic to non-target organisms. More than half of these contaminants are chiral and have been measured at different enantiomeric proportions in diverse ecosystems. Enantiomers can exhibit different toxicodynamics and toxicokinetics, and thus, can cause different toxic effects. Therefore, the enantiomeric distribution in occurrence cannot be neglected as the toxicity and other adverse biological effects are expected to be enantioselective. Hence, this review aims to reinforce the recognition of the stereochemistry in environmental risk assessment (ERA) of chiral CEC and gather up-to-date information about the current knowledge regarding the enantioselectivity in ecotoxicity of PHAR, ID, persistent pollutants (PCBs and PBDEs) and chiral ionic solvents present in freshwater and agricultural soil ecosystems. We performed an online literature search to obtain state-of-the-art research about enantioselective studies available for assessing the impact of these classes of CEC. Ecotoxicity assays have been carried out using organisms belonging to different trophic levels such as microorganisms, plants, invertebrates, and vertebrates, and considering ecologically relevant aquatic and terrestrial species or models organisms recommended by regulatory entities. A battery of ecotoxicity assays was also reported encompassing standard acute toxicity to sub-chronic and chronic assays and different endpoints as biomarkers of toxicity (e.g., biochemical, morphological alterations, reproduction, behavior, etc.). Nevertheless, we call attention to the lack of knowledge about the potential enantioselective toxicity of many PHAR, ID, and several classes of industrial compounds. Additionally, several questions regarding key species, selection of most appropriate toxicological assays and ERA of chiral CEC are addressed and critically discussed.

Polychlorinated biphenyls in bovine milk from a typical informal electronic waste recycling and related source regions in southern India before and after the COVID-19 pandemic outbreak

For more than a decade, Chennai city in southern India has been evidenced with informal electronic waste (e-waste) recycling and open burning practices as the potential sources for polychlorinated biphenyls (PCBs). PCBs can bioaccumulate in livestock particularly cows grazing on the contaminated soil. The outbreak of the COVID-19 pandemic led to additional challenges associated with waste management practices. Hence this study aims to elucidate twenty-five PCB congeners in bovine milk from the previously reported PCB source regions in Chennai and the suburbs before and after about three years of the pandemic outbreak along electronic waste recycling (EWR), open burning dumps (OBD), and residential (RES) transects. The geomean concentration of Ʃ25PCBs in ng/g lipid weight (lw) followed a decreasing trend of EWR (13 ng/g lw) > OBD (8 ng/g lw) > RES (4 ng/g lw). Over 80 % of PCBs stemmed from EWR and OBD transects before and after the pandemic. However, a significant surge in the level of PCB-52 was observed in the OBD transect after the pandemic outbreak. Most toxic PCB congeners, PCB-126 and -169 were significant contributors to TEQs in EWR and OBD transects and can be reasoned with the burning of waste materials and mixed plastics in these transects. The highest average daily dose (ADD) exposure risk was for children from EWR and was significantly higher (p < 0.05) than other transects. Mean ADD-induced TEQ (6.6 pg TEQ/kg-bw/day) from the cows grazing around Kodungaiyur dumpsite slightly exceeded the EU guideline of 5.5 pg TEQ/kg-bw/day after the outbreak of the pandemic due to PCB-126. However, none of the samples exceeded the US FDA (1.5μg/g milk fat) recommendation limits for PCBs in milk fat. Prolonged exposure to such persistent organic pollutants interlinked with the burning of mixed waste in the open dumps can be a public health concern.

Toward a comprehensive understanding of alicyclic compounds: Bio-effects perspective and deep learning approach

The escalating use of alicyclic compounds in modern industrial production has led to a rapid increase of these substances in the environment, posing significant health hazards. Addressing this challenge necessitates a comprehensive understanding of these compounds, which can be achieved through the deep learning approach. Graph neural networks (GNN) known for its' extraordinary ability to process graph data with rich relationships, have been employed in various molecular prediction tasks. In this study, alicyclic molecules screened from PCBA, Toxcast and Tox21 are made as general bioactivity and biological targets' activity prediction datasets. GNN-based models are trained on the two datasets, while the Attentive FP and PAGTN achieve best performance individually. In addition, alicyclic carbon atoms make the greatest contribution to biological activity, which indicate that the alicycle structures have significant impact on the carbon atoms' contribution. Moreover, there are terrific number of active molecules in other public datasets, indicates that alicyclic compounds deserve more attention in POPs control. This study uncovered deeper structural-activity relationships within these compounds, offering new perspectives and methodologies for academic research in the field.

Ferroptosis Induced by Pollutants: An Emerging Mechanism in Environmental Toxicology

Environmental pollutants have been recognized for their ability to induce various adverse outcomes in both the environment and human health, including inflammation, apoptosis, necrosis, pyroptosis, and autophagy. Understanding these biological mechanisms has played a crucial role in risk assessment and management efforts. However, the recent identification of ferroptosis as a form of programmed cell death has emerged as a critical mechanism underlying pollutant-induced toxicity. Numerous studies have demonstrated that fine particulates, heavy metals, and organic substances can trigger ferroptosis, which is closely intertwined with lipid, iron, and amino acid metabolism. Given the growing evidence linking ferroptosis to severe diseases such as heart failure, chronic obstructive pulmonary disease, liver injury, Parkinson's disease, Alzheimer's disease, and cancer, it is imperative to investigate the role of pollutant-induced ferroptosis. In this review, we comprehensively analyze various pollutant-induced ferroptosis pathways and intricate signaling molecules and elucidate their integration into the driving and braking axes. Furthermore, we discuss the potential hazards associated with pollutant-induced ferroptosis in various organs and four representative animal models. Finally, we provide an outlook on future research directions and strategies aimed at preventing pollutant-induced ferroptosis. By enhancing our understanding of this novel form of cell death and developing effective preventive measures, we can mitigate the adverse effects of environmental pollutants and safeguard human and environmental health.

A novel mechanism of enhanced PCBs degradation associated with nitrogen in the rhizosphere of the wetland plant Myriophyllum aquaticum

Co-contamination of polychlorinated biphenyls (PCBs) and nitrogen (N) is widespread. Here, N removal and PCBs degradation were investigated in constructed wetlands populated with Myriophyllum aquaticum, and the role of N in PCBs degradation was explored as well. Nearly 97% of N was removed in the planted system, whereas less than 40% was removed in the plant-free system. Compared to the treatment with plants and no N amendment, N addition enhanced plant growth by 31.9% and PCBs removal by 9.90%. PCBs attenuation was mainly attributed to microbial degradation rather than plant uptake. Using DNA stable-isotope probing, 26 operational taxonomic units were identified across all treatments, of which 25 were linked to PCBs degradation for the first time. Some PCB-degraders were associated with nitrification/denitrification and were significantly enriched in the treatment that included both plants and N application, indicating that PCBs degradation was promoted by recruiting ammonia-oxidising and denitrifying microbes with PCBs metabolic ability. This was confirmed by the higher A13/A12 ratios for the bphC, amoA, and nirK genes and their significant positive correlations. Overall, the findings clarify the novel mechanism by which N promotes PCBs degradation in constructed wetlands and offers a theoretical basis for efficiently removing inorganic elements and persistent organic pollutants.

Legacy and emerging contaminants in marine mammals from Argentina

Marine mammals are recognized sentinels of ecosystem health. They are susceptible to the accumulation and biomagnification of pollutants, which constitute one of the greatest threats to their survival. Legacy, such as organochlorine pesticides, and emerging contaminants, like microplastics and pharmaceuticals, may have effects on marine mammals' health at individual and population levels. Therefore, the evaluation of the risks associated with pollutants in this group is of great importance. The aim of this review is to provide information on the occurrence of legacy and emerging contaminants in marine mammals that inhabit Argentine waters. Also, to identify knowledge gaps and suggest best practices for future research. Reports of legacy contaminants referring to organochlorine pesticides and polychlorinated biphenyls were found in five species of cetaceans and two of pinnipeds. With respect to emerging pollutants, the presence of plastics was only evaluated in three species. Reported data was from at least a decade ago. Therefore, it is necessary to update existing information and conduct continuous monitoring to assess temporary trends in pollutants. All the studies were carried out in the province of Buenos Aires and Northern Patagonia indicating a knowledge gap in the southern zone of the Argentine Sea. In addition, pollutants of global environmental concern that have not been studied in Argentina are discussed. Future studies should fill these gaps and a greater effort to understand the relationships between pollutants and their effects on marine mammals is suggested. This issue will make it possible to determine thresholds for all the substances and species evaluated in order to carry out more detailed risk assessments and make decisions for the conservation of marine mammals in Argentine waters.

Sources of the Elevating Polycyclic Aromatic Hydrocarbon Pollution in the Western South China Sea and Its Environmental Implications

The environmental implications of polycyclic aromatic hydrocarbons (PAHs) caused by the vigorous development of offshore oil exploitation and shipping on the marine ecosystem are unclear. In this study, the PAH concentrations were systematically characterized in multiple environmental media (i.e., atmosphere, rainwater, seawater, and deep-sea sediments) in the western South China Sea (WSCS) for the first time to determine whether PAH pollution increased. The average ∑15PAHs (total concentration of 15 US EPA priority controlled PAHs excluding naphthalene) in the water of WSCS has increased and is higher than the majority of the oceans worldwide due to the synergistic influence of offshore oil extraction, shipping, and river input. The systematic model comparison confirms that the Ksoot-air model can more accurately reflect the gas-particle partitioning of PAHs in the atmosphere of the WSCS. We also found that the vertical migration of the elevating PAHs is accelerated by particulate matter, driving the migration of atmospheric PAHs to the ocean through dry and wet deposition, with 16% being contributed by the particle phase. The particulate matter sinking alters the PAH distribution in the water column and generates variation in source apportionment, while the contribution of PAHs loaded on them (>20%) to the total PAH reserves cannot be ignored as before. Hence, the ecological threat of PAHs increases by the oil drilling and shipping industry, and the driving force of particulate matter deserves continuous attention.

Can water dating trace the transport history of HCHs in the ocean?

Long-range atmospheric and oceanic transport play a crucial role in the accumulation of persistent organic pollutants (POPs), including hexachlorocyclohexanes (HCHs), in the Arctic Ocean. Herein, transient tracers, specifically chlorofluorocarbon-12 and sulfur hexafluoride, were used to determine the ventilation time of HCHs. Results revealed that dissolved HCHs can penetrate to a depth of ~500 m in the western Arctic Ocean, corresponding to water masses with a mean age of 45 ± 14 years. The average long-range transport time for α-HCH from initial atmospheric release to entering the western Arctic Ocean was estimated to be >30 ± 5 years, indicating continued moderate to high ecological risks from HCHs in the Arctic. This study demonstrates that transient tracers serve as effective water dating tools to elucidate the transport history of stable POPs in the ocean, contributing to a better understanding of their environmental characteristics and fate.

Fluorescent Visualization of Chemical Profiles across the Air-Water Interface

Chemical transfer across the air-water interface is one of the most important geochemical processes of global significance. Quantifying such a process has remained extremely challenging due to the lack of suitable technologies to measure chemical diffusion across the air-water microlayer. Herein, we present a fluorescence optical system capable of visualizing the formation of the air-water microlayer with a spatial resolution of 10 μm and quantifying air-water diffusion fluxes using pyrene as a target chemical. We show for the first time that the air-water microlayer is composed of the surface microlayer in water (∼290 ± 40 μm) and a diffusion layer in air (∼350 ± 40 μm) with 1 μg L-1 of pyrene. The diffusion flux of pyrene across the air-water interface is derived from its high-resolution concentration profile without any pre-emptive assumption, which is 2 orders of magnitude lower than those from the conventional method. This system can be expanded to visualize diffusion dynamics of other fluorescent chemicals across the air-water interface and provides a powerful tool for furthering our understanding of air-water mass transfer of organic chemicals related to their global cycling.

Assessing human internal exposure to chemicals at different physical activity levels: A physiologically based kinetic (PBK) model incorporating metabolic equivalent of task (MET)

Physical activity levels have the potential to impact human internal exposure to environmental chemicals. However, the current lack of simple modeling approaches hinders the high-throughput screening of chemical exposure at different physical activity levels. To address this gap, this study proposes a straightforward model for assessing human internal exposure to chemicals. Our approach is based on the physiologically based kinetic (PBK) model and utilizes the metabolic equivalent of task (MET) to characterize internal exposure to chemicals at varying activity levels. To facilitate the application of this model, we have developed an Excel-based operation tool, allowing users to easily modify the MET value and generate simulation results for different physical activity levels. The simulation results demonstrate that as physical activity levels increase, the biotransfer factors (BTFs) of chemicals decrease, suggesting that higher physical activity levels reduce the bioaccumulation potential of chemicals. The intensified physical activity enhances the overall elimination kinetics of chemicals from the human body. However, the simulated concentrations of chemicals in the human body increase with higher physical activity levels, due to the significantly increased external exposure to chemicals, such as through inhalation. Our proposed modeling approach, along with the operational tool, enables high-throughput simulation of human chronic internal exposure to chemicals at different physical activity levels, where the findings can assist in screening chemicals for further health risk assessment. To accomplish this, the model incorporates certain assumptions and utilizes generic model input values. However, due to the intricate nature of the interaction between external and internal exposures at different physical activity levels, validating the simulation through experimental studies becomes challenging and is not performed in this study. For future studies, we recommend incorporating more MET-related physiological input variables, improving energy balance estimates, comprehending external exposure estimates, and conducting cohort studies to enhance and validate the proposed modeling approach.

Applicability Domains Based on Molecular Graph Contrastive Learning Enable Graph Attention Network Models to Accurately Predict 15 Environmental End Points

In silico models for predicting physicochemical properties and environmental fate parameters are necessary for the sound management of chemicals. This study employed graph attention network (GAT) algorithms to construct such models on 15 end points. The results showed that the GAT models outperformed the previous state-of-the-art models, and their performance was not influenced by the presence or absence of compounds with certain structures. Molecular similarity density (ρs) was found to be a key metrics characterizing data set modelability, in addition to the proportion of compounds at activity cliffs. By introducing molecular graph (MG) contrastive learning, MG-based ρs and molecular inconsistency in activities (IA) were calculated and employed for characterizing the structure-activity landscape (SAL)-based applicability domain ADSAL{ρs, IA}. The GAT models coupled with ADSAL{ρs, IA} significantly improved the prediction coefficient of determination (R2) on all the end points by an average of 14.4% and enabled all the end points to have R2 > 0.9, which could hardly be achieved previously. The models were employed to screen persistent, mobile, and/or bioaccumulative chemicals from inventories consisting of about 106 chemicals. Given the current state-of-the-art model performance and coverage of the various environmental end points, the constructed models with ADSAL{ρs, IA} may serve as benchmarks for future efforts to improve modeling efficacy.

Exploring the role of microbes for the management of persistent organic pollutants

Persistent organic pollutants (POPs) are chemicals which have been persisting in the environment for many years due to their longer half-lives. POPs have gained attention over the last few decades due to the unsustainable management of chemicals which led to their widespread and massive contamination of biota from different strata and environments. Due to the widespread distribution, bio-accumulation and toxic behavior, POPs have become a risk for organisms and environment. Therefore, a focus is required to eliminate these chemicals from the environment or transform into non-toxic forms. Among the available techniques for the removal of POPs, most of them are inefficient or incur high operational costs. As an alternative to this, microbial bioremediation of POPs such as pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pharmaceuticals and personal care products is much more efficient and cost-effective. Additionally, bacteria play a vital role in the biotransformation and solubilization of POPs, which reduces their toxicity. This review specifies the Stockholm Convention that evaluates the risk profile for the management of existing as well as emerging POPs. The sources, types and persistence of POPs along with the comparison of conventional elimination and bioremediation methods of POPs are discussed comprehensively. This study demonstrates the existing bioremediation techniques of POPs and summaries the potential of microbes which serve as enhanced, cost-effective, and eco-friendly approach for POPs elimination.

Construction, evaluation, and AOP framework-based application of the EpPRS as a genetic surrogate for assessing environmental pollutants

BACKGROUND

Environmental pollutant measurement is essential for accurate health risk assessment. However, the detection of humans' internal exposure to pollutants is cost-intensive and consumes time and energy. Polygenic risk scores (PRSs) have been widely applied in genetic studies of complex trait diseases. It is important to construct a genetically relevant environmental surrogate for pollutant exposure and to explore its utility for disease prediction and risk assessment.

OBJECTIVES

This study enrolled 714 individuals with complete genomic data and exposomic data on 22 plasma-persistent organic pollutants (POPs).

METHODS

We first conducted 22 POP genome-wide association studies (GWAS) and constructed the corresponding environmental pollutant-based PRS (EpPRS) by clumping and P value thresholding (C + T), lassosum, and PRS-CS methods. The best-fit EpPRS was chosen by its regression R2. An adverse outcome pathway (AOP) framework was developed to assess the effects of contaminants on candidate diseases. Furthermore, Mendelian randomization (MR) analysis was performed to explore the causal association between POPs and cancer risk.

RESULTS

The C + T method produced the best-performing EpPRSs for 7 PCBs and 4 PBDEs. EpPRSs replicated the correlations of environmental exposure measurements based on consistent patterns. The diagnostic performance of type 2 diabetes mellitus (T2DM) PRS was improved by the combined model of T2DM-EpPRS of PCB126/BDE153. Finally, the AKT1-mediated AOP framework illustrated that PCB126 and BDE153 may increase the risk of T2DM by decreasing AKT1 phosphorylation through the cGMP-PKG pathway and promoting abnormal glucose homeostasis. MR analysis showed that digestive system tumors, such as colorectal cancer and biliary tract cancer, are more sensitive to POP exposure.

CONCLUSIONS

EpPRSs can serve as a proxy for assessing pollutant internal exposure. The application of the EpPRS to disease risk assessment can reveal the toxic pathway and mode of action linking exposure and disease in detail, providing a basis for the development of environmental pollutant control strategies.

Physical exercise and persistent organic pollutants

Exposure to the legacy and emerging persistent organic pollutants (POPs) incessantly has become an important threat to individual health, which is closely related to neurodevelopment, endocrine and cardiovascular homeostasis. Exercise, on the other hand, has been consistently shown to improve physical fitness. Whereas associations between traditional air pollutants, exercise and lung function have been thoroughly reviewed, reviews on associations between persistent organic pollutants and exercise are scarce. Hence, a literature review focused on exercise, exposure to POPs, and health risk assessment was performed for studies published from 2004 to 2022. The purpose of this review is to provide an overview of exposure pathways and levels of POPs during exercise, as well as the impact of exercise on health concerns attributable to the redistribution, metabolism, and excretion of POPs in vivo. Therein lies a broader array of exercise benefits, including insulin sensitizing, mitochondrial DNA repair, lipid metabolism and intestinal microecological balance. Physical exercise is conducive to reduce POPs body burden and resistant to health hazards of POPs generally. Besides, individual lipid metabolism condition is a critical factor in evaluating potential link in exercise, POPs and health effects.

Mercury Exposure and Habitat Fragmentation Affect the Movement, Foraging Behavior, and Search Efficiency of the Marsh Periwinkle (Littorina irrorata)

The interactions between habitat fragmentation and other stressors are considered a key knowledge gap. The present study tested the hypotheses that mercury enhances the effects of fragmentation by (1) reducing the cumulative daily movement of organisms, (2) shifting their foraging behavior, and (3) altering the vertical movement of the marsh periwinkle (Littoraria irrorata) in a field experiment. Random walk simulations were used to access how changes in movement affect the search efficiency of organisms in the long term. Eighteen 1.5 m2 plots were constructed in a salt marsh where landscapes characteristics were manipulated to reach three different levels of habitat cover. Daily movement of 12 marked control and mercury-exposed snails were measured in each plot. Bayesian models were used to analyze the data and evidence ratios were used to test the hypotheses. The results showed that the effects of fragmentation were consistent in both control and exposed treatments, with an increase in the cumulative displacement of organisms. However, mercury significantly reduced the movement of organisms in all levels of fragmentation, shifting their foraging behavior (evidence ratio > 1000). Exposed snails were more likely to be found inactive in comparison with the control treatment (evidence ratio > 1000). Fragmentation also reduced the vertical movement of organisms in both treatments. In contrast, mercury increased the vertical movement of organisms (evidence ratio > 1000). The search efficiency of organisms also increased in a highly fragmentated landscape, suggesting that changes in foraging behavior are likely due to reduced resources and consequently increase in foraging effort. The present study shows that mercury exposure can enhance the effects of habitat fragmentation by changing organisms' movement, foraging behavior, and search efficiency. Environ Toxicol Chem 2023;42:1971-1981. © 2022 SETAC.

Sea turtle egg yolk and albumen as biomonitoring matrices for maternal burdens of organic pollutants

To establish the use of eggs as biomonitoring tools for maternal body burdens, we investigated the mother-to-egg ratio of 56 PCB, 12 OCP and 34 PBDE unique compounds from maternal plasma into replicate egg yolk and albumen samples in the loggerhead turtle (Caretta caretta) as a case study of a threatened migratory marine species. We applied robust Regression on Order Statistics to fully account for the information in both censored and uncensored data. Our results added new insights into the use of yolk as a suitable biomonitoring matrix; the difference between yolk and albumen which were previously analysed as a homogeneous mixture; and the value of accounting for censored data. Overall, compound-specific mother-to-egg ratios need to be considered when translating yolk levels back to maternal pollution burdens, and when assessing the risk to the subsequent generations of turtle embryos.

Persistent organic pollutants in Croatian breast milk: An overview of pollutant levels and infant health risk assessment from 1976 to the present

This review article summarizes our research of persistent organic pollutants (POPs) in human milk from Croatian mothers over the last few decades. Our studies make up the bulk of all POPs research in human milk in Croatia and show a state-of-the art in the research area. The first investigations were made in 1970's. Aim of our review article is to document the comprehensive results over several decades as the best tool to: 1.) contribute to understanding of POPs and their potential health risks, 2.) evaluate effectiveness of legislative bans and restrictions on human exposure to POPs in Croatia, and 3.) to suggest further actions. In our review we discuss: 1.) Human milk between 2011 and 2014 - evaluation of interrelations of organochlorine pesticides (OCP) and polychlorinated biphenyls (PCB) in human milk and their association with the mother's age and parity using artificial intelligence methods; and our yet unpublished research data on health risks for infants assessed through daily PCB and OCP intake. 2.) Time trends of PCB and OCP in human milk between 1976 and 2014. 3.) polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran (PCDD/F) in human milk in 2000., and yet unpublished data on PCDD/F and polybrominated diphenyl ethers (PBDE) in 2014.

A data-driven analysis of global research trends on dirty-dozen persistent organic pollutants

The occurrence, distribution, and fate of persistent organic pollutants (POPs) have been extensively studied worldwide; however, the patterns and dynamics of scientific publications on POPs are still unclear. In this study, the research trends on dirty dozen POPs, which are identified under the Stockholm Convention (SC) for immediate action were investigated and evaluated in a broad context to obtain up-to-date information. For this purpose, bibliometric analysis was carried out between 1945 and 2021 using the Web of Science (WoS) database. A total of 197,029 publications were analyzed. "Environmental Sciences" was the most popular research category and the USA was the leading country in dirty dozen POPs studies. The research hotspots are related to the most used keywords such as "Polychlorinated Biphenyls", "Dioxin" and "Persistent Organic Pollutants". In the evaluation of keyword clusters with highlighted research points, 7 clusters were obtained from the publications, which are related to the chemical properties, synthesis, structures, health effects, and analysis methods of dirty dozen POPs. The number of publications and, accordingly, the scientific interest in dirty dozen POPs listed under the SC has not reached equilibrium and continues regardless of the level of development of countries in the world.

Insight into the Mechanism Underlying Dehalococcoides mccartyi Strain CBDB1-Mediated B12-Dependent Aromatic Reductive Dehalogenation

Anaerobic bacteria transform aromatic halides through reductive dehalogenation. This dehalorespiration is catalyzed by the supernucleophilic coenzyme vitamin B₁₂, cob(I)alamin, in reductive dehalogenases. So far, the underlying inner-sphere electron transfer (ET) mechanism has been discussed controversially. In the present study, all 36 chloro-, bromo-, and fluorobenzenes and full-size cobalamin are analyzed at the quantum chemical density functional theory level with respect to a wide range of theoretically possible inner-sphere ET mechanisms. The calculated reaction free energies within the framework of Co^I···X (X = F, Cl, and Br) attack rule out most of the inner-sphere pathways. The only route with feasible energetics is a proton-coupled two-ET mechanism that involves a B₁₂ side-chain tyrosine (modeled by phenol) as a proton donor. For 12 chlorobenzenes and 9 bromobenzenes with experimental data from Dehalococcoides mccartyi strain CBDB1, the newly proposed PC-TET mechanism successfully discriminates 16 of 17 active from 4 inactive substrates and correctly predicts the observed regiospecificity to 100%. Moreover, fluorobenzenes are predicted to be recalcitrant in agreement with experimental findings. Conceptually, based on the Bell-Evans-Polanyi principle, the computational approach provides novel mechanistic insights and may serve as a tool for predicting the energetic feasibility of reductive aromatic dehalogenation.

Estradiol protects female mice from hyperuricemia induced by PCB138 exposure

Polychlorinated biphenyls (PCBs) are a type of persistent organic pollutant (POP). Our previous study demonstrated that exposure to 0.5-50 μg/kg bw PCB138 during postnatal days (PND) 3-21 led to elevated serum uric acid (UA) levels and kidney injury in adult male mice. Given that the prevalence of hyperuricemia (HUA) is significantly lower in women than in men, it is worth investigating whether POP-induced HUA and its secondary kidney injury have sexual dimorphism. Herein, we exposed female mice to 0.5-50 μg/kg bw PCB138 during PND 3-21, resulting in elevated serum UA levels, but without causing significant kidney damage. Concurrently, we found a negative correlation between serum 17β-estradiol (E2) and serum UA levels. We also observed down-regulation of estrogen receptor (ER) protein levels in the kidneys of the PCB138-exposed groups. Furthermore, our study showed that E2 rescued the increased UA level and cytotoxicity caused by HUA in human renal tubular epithelial (HK-2) cells. Collectively, our findings suggest that E2 likely plays a crucial protective role in PCB138-induced HUA and kidney injury in female mice. Our research highlights the existence of sexual dimorphism in kidney injury secondary to HUA induced by POPs, which could provide guidance for individuals of different genders in preventing kidney injury caused by environmental factors.

Peroxymonosulfate activation by graphene oxide-supported 3D-MoS2/FeCo2O4 sponge for highly efficient organic pollutants degradation

To address conventional powder catalysts' recovery and aggregation issues that greatly restrain their practical application, a recoverable graphene oxide (GO)-supported 3D-MoS₂/FeCo₂O₄ sponge (SFCMG) was developed through a simple impregnation pyrolysis method. SFCMG can efficiently activate peroxymonosulfate (PMS) to produce reactive species for rapid degradation of rhodamine B (RhB), with 95.0% and 100% of RhB being removed within 2 min and 10 min, respectively. The presence of GO enhances the electron transfer performance of the sponge, and the three-dimensional melamine sponge serves as a substrate to provide a highly dispersed carrier for FeCo₂O₄ and MoS₂/GO hybrid sheets. SFCMG exhibits a synergistic catalytic effect of Fe and Co, and facilitates the redox cycles of Fe(III)/Fe(II) and Co(III)/Co(II) by MoS₂ co-catalysis, which enhances its catalytic activity. Electron paramagnetic resonance results demonstrate that SO₄^•-, ·O₂^- and ¹O₂ are all involved in SFCMG/PMS system, and ¹O₂ played a prominent role in RhB degradation. The system has good resistance to anions (Cl^-, SO₄^2-, and H₂PO₄^-) and humic acid and excellent performance for many typical contaminants degradation. Additionally, it works efficiently over a wide pH range (3-9) and possesses high stability and reusability with the metal leaching far below the safety standards. The present study extends the practical application of metal co-catalysis and offers a promising Fenton-like catalyst for the treatment of organic wastewater.

Salinity determines performance, functional populations, and microbial ecology in consortia attenuating organohalide pollutants

Organohalide pollutants are prevalent in coastal regions due to extensive intervention by anthropogenic activities, threatening public health and ecosystems. Gradients in salinity are a natural feature of coasts, but their impacts on the environmental fate of organohalides and the underlying microbial communities remain poorly understood. Here we report the effects of salinity on microbial reductive dechlorination of tetrachloroethene (PCE) and polychlorinated biphenyls (PCBs) in consortia derived from distinct environments (freshwater and marine sediments). Marine-derived microcosms exhibited higher halotolerance during PCE and PCB dechlorination, and a halotolerant dechlorinating culture was enriched from these microcosms. The organohalide-respiring bacteria (OHRB) responsible for PCE and PCB dechlorination in marine microcosms shifted from Dehalococcoides to Dehalobium when salinity increased. Broadly, lower microbial diversity, simpler co-occurrence networks, and more deterministic microbial community assemblages were observed under higher salinity. Separately, we observed that inhibition of dechlorination by high salinity could be attributed to suppressed viability of Dehalococcoides rather than reduced provision of substrates by syntrophic microorganisms. Additionally, the high activity of PCE dechlorinating reductive dehalogenases (RDases) in in vitro tests under high salinity suggests that high salinity likely disrupted cellular components other than RDases in Dehalococcoides. Genomic analyses indicated that the capability of Dehalobium to perform dehalogenation under high salinity was likely owing to the presence of genes associated with halotolerance in its genomes. Collectively, these mechanistic and ecological insights contribute to understanding the fate and bioremediation of organohalide pollutants in environments with changing salinity.

Remediation of environmentally persistent organic pollutants (POPs) by persulfates oxidation system (PS): A review

Over the past few years, persistent organic pollutants (POPs) exhibiting high ecotoxicity have been widely detected in the environment. Persulfate-oxidation hybrid system is one of the most widely used novel advanced oxidation techniques and is based on the persulfate generation of SO₄^-∙ and ∙OH from persulfate to degrade POPs. The overarching aim of this work is to provide a critical review of the variety of methods of peroxide activation (e.g., light activated persulfate, heat-activated persulfate, ultrasound-activated persulfate, electrochemically-activated persulfate, base-activated persulfate, transition metal activated persulfate, as well as Carbon based material activated persulfate). Specifically, through this article we make an attempt to provide the important characteristics and uses of main activated PS methods, as well as the prevailing mechanisms of activated PS to degrade organic pollutants in water. Finally, the advantages and disadvantages of each activation method are analyzed. This work clearly illustrates the benefits of different persulfate activation technologies, and explores persulfate activation in terms of Sustainable Development Goals, technical feasibility, toxicity assessment, and economics to facilitate the large-scale application of persulfate technologies. It also discusses how to choose the most suitable activation method to degrade different types of POPs, filling the research gap in this area and providing better guidance for future research and engineering applications of persulfates.

Historical evolution of polycyclic aromatic hydrocarbon pollution in Chaihe Reservoir from 1863 to 2018

Pollution from polycyclic aromatic hydrocarbons (PAHs) spreads and changes worldwide. The pollution evolution in the regional water environment evolves in response to multiple factors, requiring considerable attention. PAH heterogeneity in the sediment core from Chaihe Reservoir was investigated to indicate dynamic changes in PAH pollution levels and sources and propose recommendations for controlling PAHs. Dynamic PAH patterns showed that the overall decline in PAH pollution was in association with local anthropogenic activities, temperature, and precipitation over the period 1863-2018. Nevertheless, coal, oil, and natural gas consumptions still played significant roles in transferring PAHs to the reservoir. Meanwhile, there were dominant local origins, including grass, wood, and coal combustion. The results highlight that the joint action of natural and anthropogenic interventions mitigated PAH pollution in the reservoir. Promoting improved fuels, new energy vehicles, and cleaner energy may further lower PAH pollution.

Mapping the Contribution of Biomass Burning to Persistent Organic Pollutants in the Air of the Indo-China Peninsula Based on a Passive Air Monitoring Network

Biomass burning (BB) is an important source of atmospheric persistent organic pollutants (POPs) across the world. However, there are few field-based regional studies regarding the POPs released from BB. Due to the current limitations of emission factors and satellites, the contribution of BB to airborne POPs is still not well understood. In this study, with the simultaneous monitoring of BB biomarkers and POPs based on polyurethane foam-based passive air sampling technique, we mapped the contribution of BB to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Indo-China Peninsula. Spearman correlations between levoglucosan and 16 PCBs (r_s = 0.264-0.767, p < 0.05) and 2 OCPs (r_s = 0.250-0.328, p < 0.05) confirmed that BB may facilitate POP emissions. Source apportionment indicated that BB contributed 9.3% to the total PCB and OCP mass. The high contribution of positive matrix factorization-resolved BB to PCBs and OCPs was almost consistent with their concentration distributions in the open BB season but not completely consistent with those in the pre-monsoon and/or monsoon seasons. Their contribution distributions may reflect the use history and geographic distribution in secondary sources of POPs. The field-based contribution dataset of BB to POPs is significant in improving regional BB emission inventories and model prediction.

Assessing the health risk of hyperuricemia in participants with persistent organic pollutants exposure - a systematic review and meta-analysis

Based on a systematic review and meta-analysis of articles published in PubMed, Embase, Cochrane, and Web of Science, we identified nine articles that provide evidence of the relationship between persistent organic pollutants and hyperuricemia. Our researchers assess the quality of the included studies and their risk of bias using the recommended method and tool. This study uses meta-analyses of the random effects of each exposure and outcome to estimate combined odds ratios (ORs) and 95% confidence intervals (CIs). We found that the risk of hyperuricemia was strongly associated with three perfluorinated compounds, PFNA, PFOA, and PFOS, with the OR(95%CI) of 1.26 (1.07-1.47), 1.44(1.15-1.79), and 1.23(1.01-1.50) respectively. We also found a weak association between two other perfluorinated compounds, PFDA and PFHxS. Other than that, the summary ORs (95% CIs) of incident hyperuricemia were 2.34 (1.79-3.08) for DDT, 3.25(2.40-4.39) for DDE, 2.57 (1.37-4.81) for PCBs and 3.05(2.22-4.19) in trans-nonanchlor. Therefore, DDT and its breakdown product, DDE, PCBs, and trans-nonanchlor have also been linked with an increased risk of hyperuricemia in humans. This study finds that persistent organic pollutant is a critical factor for hyperuricemia, and further studies in specific regions will be considered in the future.

Brominated flame retardants (PBDEs and HBCDs) and perfluoroalkyl substances (PFASs) in wild boars (Sus scrofa) from Central Italy

Twenty-six samples of wild boar liver and muscle from the Central Apennine Mountain (Italy) were analysed for 19 perfluoro-alkyl substances (PFASs), 10 polybrominated diphenylethers (PBDEs) and 3 hexabromocyclododecanes (HBCDs). All samples were analysed by gas chromatography-tandem mass spectrometry for PBDEs and liquid chromatography-tandem mass spectrometry for PFASs and HBCDs, using an in-house developed analytical procedure. The brominated flame retardants (BFR) levels in livers were negligible: Σ₁₀PBDEs reached a maximum value of 0.079 μg/kg, whereas HBCDs were not quantified in almost all of the samples analysed. BFR concentrations in muscles were higher, but not significantly therefore, for Σ₁₀PBDEs lower bound, a mean value of 0.045 μg/kg (0.005-0.155 μg/kg range) was measured, while α-HBCD was quantified with a maximum of 0.084 μg/kg in 9 of the samples. Only two muscles contained all 3 HBCD isomers at concentrations of approximately 0.200 μg/kg. Σ₁₉PFAS in the 26 wild boar livers was in the range 31.9-228 μg/kg, with a mean value of 87.7 μg/kg, reaching levels significantly higher than in muscles, which exhibited a mean concentration of 3.08 μg/kg (0.59-9.12 μg/kg range). Perfluorooctanesulfonic acid (PFOS) was the most prevalent compound in all liver samples, accounting for more than half of the total PFASs contamination, confirming that the liver is the primary target organ for PFOS exposure Perfluorotridecanoic acid (PFTrDA), which accounts for 25-30-% of the total contamination, was the most abundant compound in the muscle, followed by PFOS. The estimated daily intake (EDIs) of BFRs remained below the estimated chronic human daily dietary intake (D_r,h) defined from European Food Safety Authority (EFSA). Furthermore, the exposure to PFASs in muscle was 7.7 times lower than the EFSA's tolerable daily intake (TDI). In contrast, exposure due to liver consumption was significant: the EDI exceeded the EFSA's 2020 TDI by approximately 7 times.

Formation and Inventory of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Other Byproducts along Manufacturing Processes of Chlorobenzene and Chloroethylene

Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated byproducts [e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] formed during the commercial manufacturing processes and present in organochlorine products are rarely reported. The knowledge on the occurrences and fate of unintentional persistent organic chemicals in the manufacturing of organochlorine chemical is necessary for accurate assessment of the risks of commercial chemicals and their production. Here, PCDD/Fs were tracked throughout chlorobenzene and chloroethylene production processes (from raw materials to final products) by target analysis. Other byproducts that can further transform into PCDD/Fs were also identified by performing non-target screening. As a result, the PCDD/F concentrations were mostly the highest in bottom residues, and the octachlorinated congeners were dominant. Alkali/water washing stages may cause the formation of oxygen-containing byproducts including PCDD/Fs and acyl-containing compounds, so more attention should be paid to these stages. PCDD/Fs were of 0.17 and 0.21-1.2 ng/mL in monochlorobenzene and chloroethylene products, respectively. Annual PCDD/F emissions (17 g toxic equivalent in 2018) during chlorobenzene and chloroethylene production were estimated using PCDD/F emission factors. The results can contribute to the improvement of PCDD/F inventories for the analyzed commercial chemicals.

Co-occurrence of phthalate esters and perfluoroalkyl substances affected bacterial community and pathogenic bacteria growth in rural drinking water distribution systems

The adverse health effects of phthalate esters (PAEs) and perfluoroalkyl substances (PFAS) in drinking water have attracted considerable attention. Our study investigated the effects of PAEs and PFAS on the bacterial community and the growth of potential human pathogenic bacteria in rural drinking water distribution systems. Our results showed that the total concentration of PAEs and PFAS ranged from 1.02 × 10² to 1.65 × 10⁴ ng/L, from 4.40 to 1.84 × 10² ng/L in rural drinking water of China, respectively. PAEs concentration gradually increased and PFAS slowly decreased along the pipeline distribution, compared to concentrations in the effluents of rural drinking water treatment plants. The co-occurrence of higher concentrations of PAEs and PFAS changed the structure and function of the bacterial communities found within these environments. The bacterial community enhanced their ability to respond to fluctuating environmental conditions through up-regulation of functional genes related to extracellular signaling and interaction, as well as genes related to replication and repair. Under these conditions, co-occurrence of PAEs and PFAS promoted the growth of potential human pathogenic bacteria (HPB), therefore increasing the risk of the development of associated diseases among exposed persons. The main HPB observed in this study included Burkholderia mallei, Mycobacterium tuberculosis, Klebsiella pneumoniae, Acinetobacter calcoaceticus, Escherichia coli, and Pseudomonas aeruginosa. Contaminants including particles, microorganisms, PAEs and PFAS were found to be released from corrosion scales and deposits of pipes and taps, resulting in the increase of the cytotoxicity and microbial risk of rural tap water. These results are important to efforts to improve the safety of rural drinking water.

Adverse health effects of emerging contaminants on inflammatory bowel disease

Inflammatory bowel disease (IBD) is becoming increasingly prevalent with the improvement of people's living standards in recent years, especially in urban areas. The emerging environmental contaminant is a newly-proposed concept in the progress of industrialization and modernization, referring to synthetic chemicals that were not noticed or researched before, which may lead to many chronic diseases, including IBD. The emerging contaminants mainly include microplastics, endocrine-disrupting chemicals, chemical herbicides, heavy metals, and persisting organic pollutants. In this review, we summarize the adverse health effect of these emerging contaminants on humans and their relationships with IBD. Therefore, we can better understand the impact of these new emerging contaminants on IBD, minimize their exposures, and lower the future incidence of IBD.

Soft Magnetic Microrobots for Photoactive Pollutant Removal

"Soft" robotics based on hydrogels appears as an alternative to the traditional technology of "hard" robotics. Soft microrobots are employed for drug delivery and cell manipulation. This work develops magnetic hydrogel-based microrobots using chitosan (CHI) as the body of the micromotor and Fe₃ O₄ nanoparticles to allow for its magnetic actuation. In addition, ZnO nanoparticles are incorporated inside the CHI body of the microrobot to act as an active component for pollutants photodegradation. CHI@Fe₃ O₄ -ZnO microrobots are used for the efficient photodegradation of persistent organic pollutants (POPs). The high absorption of CHI hydrogel enhances the POP photodegradation, degrading it 75% in just 30 min. The adsorption-degradation and magnetic properties of CHI@Fe₃ O₄ -ZnO microrobots are used in five cycles while maintaining up to 60% photodegradation efficiency. The proof-of-concept present in this work represents a simple way to obtain soft microrobots with magnetic actuation and photodegradation functionalities for several water purification applications.