Environmental profile, distributions and potential sources of halogenated polycyclic aromatic hydrocarbons

Mechanism of cytochrome P450s mediated interference with glutathione and amino acid metabolisms from halogenated PAHs exposure

Epidemiological evidence indicates that exposure to halogenated polycyclic aromatic hydrocarbons (HPAHs) is associated with many adverse effects. However, the mechanisms of metabolic disorder of HPAHs remains limited. Herein, effects of pyrene (Pyr), and its halogenated derivatives (1-chloropyrene (1-Cl-Pyr), 1-bromopyrene (1-Br-Pyr)) on endogenous metabolic pathways were investigated, in human hepatoma (HepG2) and HepG2-derived cell lines expressing various human cytochrome P450s (CYPs). Non-targeted metabolomics results suggested that 1-Br-Pyr and Pyr exposure (625 nM) induced disruption in glutathione and riboflavin metabolism which associated with redox imbalance, through abnormal accumulation of oxidized glutathione, mediated by bioactivation of CYP2E1. Conversely, CYP2C9-mediated 1-Cl-Pyr significantly interfered with glutathione metabolism intermediates, including glycine, L-glutamic acid and pyroglutamic acid. Notably, CYP1A1-mediated Pyr-induced perturbation of amino acid metabolism which associated with nutrition and glycolipid metabolism, resulting in significant upregulation of most amino acids, whereas halogenated derivatives mediated by CYP1A2 substantially downregulated amino acids. In conclusion, this study suggested that Pyr and its halogenated derivatives exert potent effects on endogenous metabolism disruption under the action of various exogenous metabolic enzymes (CYPs). Thus, new evidence was provided to toxicological mechanisms of HPAHs, and reveals potential health risks of HPAHs in inducing diseases caused by redox and amino acid imbalances.

Degradation of multiple PAHs and co-contaminants by microbial consortia and their toxicity assessment

The anthropogenic activities toward meeting the energy requirements have resulted in an alarming rise in environmental pollution levels. Among pollutants, polycyclic aromatic hydrocarbons (PAHs) are the most predominant due to their persistent and toxic nature. Amidst the several pollutants depuration methods, bioremediation utilizing biodegradation is the most viable alternative. This study investigated the biodegradation efficacy using developed microbial consortium PBR-21 for 2-4 ringed PAHs named naphthalene (NAP), anthracene (ANT), fluorene (FLU), and pyrene (PYR). The removal efficiency was observed up to 100 ± 0.0%, 70.26 ± 4.2%, 64.23 ± 2.3%, and 61.50 ± 2.6%, respectively, for initial concentrations of 400 mg L-1 for NAP, ANT, FLU, and PYR respectively. Degradation followed first-order kinetics with rate constants of 0.39 d-1, 0.10 d-1, 0.08 d-1, and 0.07 d-1 and half-lifet 1 / 2  of 1.8 h, 7.2 h, 8.5 h, and 10 h, respectively. The microbial consortia were found to be efficient towards the co-contaminants with 1 mM concentration. Toxicity examination indicated that microbial-treated PAHs resulted in lesser toxicity in aquatic crustaceans (Artemia salina) than untreated PAHs. Also, the study suggests that indigenous microbial consortia PBR-21 has the potential to be used in the bioremediation of PAH-contaminated environment.

Polycyclic aromatic hydrocarbons and their halogenated derivatives in soil from Yellow River Delta: Distribution, source apportionment, and risk assessment

The distribution of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (HPAHs) in surface soils from the petroleum industrial area of the Yellow River Delta (YRD) in China were investigated. The total concentrations of 16 PAHs ranged from 19.6 to 1560 ng/g, while 22 HPAHs ranged from 2.44 to 14.9 ng/g. Moreover, a high degree of spatial distribution heterogeneity was observed for both PAHs and HPAHs, which is likely attributed to the distinct industrial activities in studied area. The combustion of biomass and petroleum were identified as primary sources of soil PAHs and HPAHs in the YRD. Furthermore, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[g,h,i]perylene exhibited high ecological risks (with risk quotients of 1.47, 1.44, and 1.02, respectively) in specific sites within the YRD. Considering the high toxicity of HPAHs and their potential joint environmental effects with PAHs, continuous attention should be directed towards the environmental risks associated with both PAHs and HPAHs.

Quantitative characterization of resident' exposure to typical semi-volatile organic compounds (SVOCs) around a non-ferrous metal smelting plant

To comprehensively characterize residents' exposure to major semi-volatile organic compounds (SVOCs), samples of indoor floor wipes, size-segregated airborne particles, gaseous air, food, and paired skin wipes were simultaneously collected from residential areas around a large non-ferrous metal smelting plant as compared with the control areas, and three typical SVOCs (including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and halogenated PAHs (HPAHs)) were determined. Comparison and correlation analysis among matrices indicated PAHs were the major contaminants emitted from metal smelting activities compared to HPAHs and PCBs, with naphthalene verified as the most important characteristic compound, and their accumulation on skin may be a comprehensive consequence of contact with floor dust and air. While patterns of human exposure pathways for the SVOCs were found to be clearly correlated to their vapor pressure, dermal absorption was the major contributor (51.1-76.3%) to total carcinogenic risk (TCR) of PAHs and HPAHs for surrounding residents, especially for low molecular weight PAHs, but dietary ingestion (98.6%) was the dominant exposure pathway to PCBs. The TCR of PAHs exceeded the acceptable level (1 × 10-4), implying smelting activities obviously elevated the health risk. This study will serve developing pertinent exposure and health risk prevention measures.

Hazardous implications of halogenated polycyclic aromatic hydrocarbons in feedstuff: Congener specificity and toxic levels in feed ingredients and feeds

Studies have shown that halogenated polycyclic aromatic hydrocarbons (HPAHs), including chlorinated (ClPAHs) and brominated PAHs (BrPAHs), could be hazardous pollutants due to their pervasive occurrence in the environment. However, their accumulation properties and toxic potentials in animal feedstuffs remain unclear. This study investigated 75 congeners of parent PAHs, ClPAHs, and BrPAHs in animal-based feed ingredients and fish and swine feeds in Japan using a GC/Orbitrap MS system. The total parent PAHs ranged from below the method detection limit ( Collapse

Key Words

• Animal feed
• HPAH derivatives
• Orbitrap GC/MS
• Risk assessment
• TEQ

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MESH Headings

• Animals
• Swine
• Polycyclic Aromatic Hydrocarbons/analysis
• Environmental Pollutants
• Gas Chromatography-Mass Spectrometry
• Japan
• Environmental Monitoring

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Grants Collapse

Affiliation(s)

Prasun Goswami National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, 305-0856, Ibaraki, Japan
Takeshi Ohura Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Nagoya 468-8502, Japan; Graduate School of Agriculture, Meijo University, 1-501 Shiogamaguchi, Nagoya 468-8502, Japan.
Ryotaro Suzuki Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Nagoya 468-8502, Japan
Natsuki Koike Graduate School of Agriculture, Meijo University, 1-501 Shiogamaguchi, Nagoya 468-8502, Japan
Mafumi Watanabe National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, 305-0856, Ibaraki, Japan
Keerthi S Guruge National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, 305-0856, Ibaraki, Japan; Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku-oraikita, Izumisano, Osaka 598-8531, Japan.

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Parent and halogenated polycyclic aromatic hydrocarbons exposure in aluminum smelter workers: Serum levels, accumulation trends, and association with health indicators

Polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (HPAHs) can be unintentionally formed and released during industrial thermal processes. However, information on internal exposure and health risks of PAHs and HPAHs for thermal industry workers is very limited. In this study, serum samples from 220 aluminum smelter workers in East China were analyzed, and the relationship between the levels of these pollutants and various health indicators was also assessed. The workers had markedly higher serum concentrations of PAHs and HPAHs than the controls. The serum concentrations of ∑13PAHs and ∑9HPAHs increased with increasing age and occupational exposure duration in male workers. A positive correlation was observed between the ∑13PAH and ∑9HPAH serum concentrations, and the concentration of ∑13PAHs was approximately 50 times higher than that of ∑9HPAHs. For benzo[a]pyrene equivalent (BaPeq)-based risk assessment, the contribution of PAHs and HPAHs to the risk was 80 % and 20 % in the workers. PAHs and HPAHs showed a positive association with pulmonary hypofunction, hypertension and abnormal electrocardiogram. This study indicates occupational exposure to these toxic pollutants remains a significant issue and provides evidence that elevated serum levels of ∑13PAHs and ∑9HPAHs may be associated with an increased risk of lung and cardiovascular diseases.

Nanopolystyrene size effect and its combined acute toxicity with halogenated PAHs on Daphnia magna

Nanoplastics (NPs, diameter <1 μm) not only have toxicity but also change the toxicity of other pollutants in water. To date, the nanopolystyrene (nano-PS) size effect and its combined toxicity with halogenated polycyclic aromatic hydrocarbons (HPAHs) remain unclear. In this study, the single toxicity, combined toxicity, and mode of action of the binary mixture of polystyrene (PS) and HPAH were examined. At the same time, the nano-PS size effect on combined toxicity was also discussed. According to our results, the 48 h acute toxicity test results showed that 30 nm PS was highly toxic (EC50-48 h = 1.65 mg/L), 200 nm PS was moderately toxic (EC50-48 h = 17.8 mg/L), and 1 μm PS was lowly toxic (EC50-48 h = 189 mg/L). The NP toxicity decreased with increasing size. HPAHs were highly toxic substances to Daphnia magna (EC50-48 h = 0.12-0.22 mg/L). The mode of action of PS and HPAHs was antagonistic according to the toxicity unit method (TU), additive index method (AI), and mixture toxicity index method (MTI). The size effect of nano-PS operates via two mechanisms: the inherent toxicity of nano-PS and the sorption of pollutants by nano-PS. The former impacts the combined toxicity more than the latter. In the binary mixed system, the larger the particle size and the higher the proportion of NPs in the system, the less toxic the system was. Linear interpolation analysis can be used to predict the combined toxicity of a mixed system with any mixing ratio.

Integration approach of transcriptomics and metabolomics reveals the toxicity of Anthracene and its chlorinated derivatives on human hepatic cells

Polycyclic aromatic hydrocarbons (PAHs) and Chlorinated PAHs (Cl-PAHs) are ubiquitous environmental contaminants. The toxicological information of anthracene (Ant) and its chlorinated derivatives is quite limited. In this study, an integrated metabolomic and transcriptomic analysis approach was adopted to assess the toxic effects triggered by Ant and its chlorinated derivatives, 2-chloroanthracene (2-ClAnt) and 9,10-dichloroanthracen (9,10-Cl2Ant), at human-relevant levels on human normal hepatocyte L02 cells. The cell viability test showed no significant effects on the viability of L02 cells exposed to Ant, 2-ClAnt and 9,10-Cl2Ant at doses of 5-500 nM for 24 h. However, based on transcriptomic analysis, Ant, 2-ClAnt and 9,10-Cl2Ant exposure at human-relevant levels obviously perturbed global gene expression in L02 cells and induced the differential expression of several genes related to cancer development. As the number of genes related to cancer development altered by 9,10-Cl2Ant is the largest, 9,10-Cl2Ant posed greater risks of tumor development than Ant and 2-ClAnt did. Metabolomics analysis demonstrated that Ant, 2-ClAnt and 9,10-Cl2Ant caused significant metabolic perturbation in L02 cells. Pathway enrichment analysis indicated that Ant, 2-ClAnt and 9,10-Cl2Ant mainly perturbed the lipid metabolism and nucleotide metabolism pathway. However, 9,10-Cl2Ant caused a wider perturbation to metabolic pathways than Ant and 2-ClAnt did. In addition, dysregulation of nucleotide metabolism perturbed by Ant, 2-ClAnt and 9,10-Cl2Ant may be associated with the genomic instability and further carcinogenesis.

Insight into personal exposure characteristics and health effects of PM2.5 and PM0.25-bound PAHs and their derivatives with different heating ways in the Fenwei Plain, China

Personal exposure (PE) to polycyclic aromatic hydrocarbons (PAHs) and their derivatives in particulate matter with two aerodynamic sizes of 2.5 and 0.25 μm (PM2.5 and PM0.25) from rural housewives was studied in the Fenwei Plain, China. A total of 15 households were divided into five different groups based on the type of solid fuel and heating device used, including biomass briquette-furnace (BBF), biomass-elevated Kang (BEK), outdoor lump coal-boiler (OLC), indoor briquette coal-stove (IBC), and electricity (ELE). The PE concentrations of the PAHs and biomarkers in urine collected from the participants were determined. The results showed that the PE concentrations of total quantified PAHs in the biomass group (i.e., BBF and BEK) were 2.2 and 2.0 times higher than those in the coal groups (i.e., OLC and IBC) in PM2.5 and PM0.25, respectively. The housewives who used biomass as fuel suffered from higher potential health impacts than the coal fuel users. The incremental lifetime cancer risk for the PAHs in PM2.5 in the BBF and BEK groups exceeded the international safety threshold. Furthermore, the PE concentrations of oxygenated PAH (o-PAHs) in PM2.5 and PM0.25 in the biomass groups and the nitrated PAHs (n-PAHs) in PM0.25 in the coal groups showed strong correlations with the biomarkers. The results of this study proved the associations between exposure to the different classes of PAHs and health hazards. The findings could also serve as a guideline in establishing efficient measures for using solid fuels for cooking and household warming in northern China.

Voyaging of halogenated polycyclic aromatic hydrocarbons, an emerging group of pollutants, on micro-mesoplastics in the marine environment

The limited existing research on the accumulation of hazardous chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs) in micro-mesoplastics (mMPs) motivated this investigation. We collected mMPs from the coastal environments of Sri Lanka and Japan. Out of 75 target compounds analyzed, 61 were detected, with total parent PAH concentrations reaching 16,300 and 1770 ng/g plastic in Sri Lanka and Japan, respectively. The total parent PAH concentrations in mMPs from the southern Sri Lankan coastline were relatively higher than those from the eastern coastline. Phenanthrene and naphthalene were the dominant parent PAH congeners in most mMP samples. Chlorinated pyrenes and brominated naphthalene were predominant among halogenated PAHs. The estimated toxic equivalency quotient (TEQ) ranged from 0.67 to 1057 ng-TEQ/g plastic, with the highest levels observed in polystyrene (PS) particles from the southern Sri Lankan coast. Benzo[a]pyrene and dibenzo[a,h]anthracene exhibited elevated TEQ for parent PAHs, whereas dichloropyrene, and dibromopyrene represented the highest TEQs for ClPAHs and BrPAHs, respectively. The data evidenced that several HPAH congeners can increase the PAH-like toxicity (∼86%) in mMPs. This study provides insights into the accumulation of parent and halogenated PAHs in mMPs, highlighting their potential combined implications in marine and terrestrial ecosystems.

Emission characteristics of (halogenated) polycyclic aromatic hydrocarbons during printed circuit board combustion and estimated emission intensity of a typical e-waste dismantling site in South China

The pollution of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (Cl/Br-PAHs) caused by electronic waste dismantling activities have attracted considerable attention. The present study investigated the emissions and formation of PAHs and Cl/Br-PAHs based on the combustion of printed circuit boards simulating electronic waste dismantling process. The emission factor of ΣPAHs was 648 ± 56 ng/g, which was much lower than that of ΣCl/Br-PAHs (8.80 × 104 ± 9.14 × 103 ng/g). From 25 to 600 °C, the emission rate of ΣPAHs reached a sub-peak of 7.39 ± 1.85 ng/(g•min) at 350 °C, then increased gradually with the fastest rate of 19.9 ± 21.8 ng/(g•min) at 600 °C, whereas that of ΣCl/Br-PAHs was the fastest at 350 °C with a rate of 597 ± 106 ng/(g•min), then decreased gradually. The present study suggested that the formation pathways of PAHs and Cl/Br-PAHs are by de novo synthesis. Low molecular weight PAHs were readily partitioned into gas and particle phases, whereas high molecular weight fused PAHs were only detected in oil phase. However, the proportion of Cl/Br-PAHs in particle and oil phases were different from that of gas phase, whereas similar to that of the total emission. In addition, PAH and Cl/Br-PAH emission factors were used to estimate the emission intensity of pyrometallurgy project in Guiyu Circular Economy Industrial Park, and it was shown that approximately 1.30 kg PAHs and 176 kg Cl/Br-PAHs would be emitted annually. This study revealed that Cl/Br-PAHs would be formed by de novo synthesis, and for the first time provided the emission factors of Cl/Br-PAHs during the heat treatment process of printed circuit board, as well as estimated the contribution of pyrometallurgy, a new electronic waste recovery technology, to environmental Cl/Br-PAH pollution, which provides potential scientific information for governmental decision-making on the control of Cl/Br-PAHs.

Biodegradation of Benzo[a]pyrene by a White-Rot Fungus Phlebia acerina: Surfactant-Enhanced Degradation and Possible Genes Involved

Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants that pose a threat to human health. Among these PAHs, benzo[a]pyrene (BaP), a five-ring compound, exhibits high resistance to biodegradation. White-rot fungus Phlebia acerina S-LWZ20190614-6 has demonstrated higher BaP degradation capabilities compared with Phanerochaete chrysosporium and P. sordida YK-624, achieving a degradation rate of 57.7% after 32 days of incubation under a ligninolytic condition. To further enhance the biodegradation rate, three nonionic surfactants were used, and the addition of 1 or 2 g·L-1 of polyethylene glycol monododecyl ether (Brij 30) resulted in nearly complete BaP biodegradation by P. acerina S-LWZ20190614-6. Interestingly, Brij 30 did not significantly affect the activity of manganese peroxidase and lignin peroxidase, but it did decrease laccase activity. Furthermore, the impact of cytochrome P450 on BaP degradation by P. acerina S-LWZ20190614-6 was found to be relatively mild. Transcriptomic analysis provided insights into the degradation mechanism of BaP, revealing the involvement of genes related to energy production and the synthesis of active enzymes crucial for BaP degradation. The addition of Brij 30 significantly upregulated various transferase and binding protein genes in P. acerina S-LWZ20190614-6. Hence, the bioremediation potential of BaP by the white-rot fungus P. acerina S-LWZ20190614-6 holds promise and warrants further exploration.

Effect of polycyclic aromatic hydrocarbons on cancer risk causally mediated via vitamin D levels

Polycyclic aromatic hydrocarbons (PAHs) widely exist in environmental substrates and are closely related to individual circulating vitamin D levels and tumorigenesis. Therefore, we proposed to evaluate the relationship between PAH exposure, vitamin D, and the risks for 14 cancer types via a causal inference framework underlying the mediation analysis. We evaluated seven urine monohydroxylated PAH (OH-PAH) and serum vitamin D concentrations of 3306 participants from the National Health and Nutrition Examination Survey between the 2013 and 2016 survey cycles and measured PAH concentrations in 150 subjects from the Nanjing cohort. We observed a significant negative dose-response relationship between increased OH-PAH levels and vitamin D deficiency. Each unit increase in ∑OH-PAHs could lead to a decrease in vitamin D levels (βadj  = -0.98, Padj  = 2.05 × 10-4 ). Body mass index could have interaction effects with ∑OH-PAHs and affect vitamin D levels. Coexposure to naphthalene and fluorene metabolites mutually affected vitamin D levels. Notably, vitamin D could causally mediate the relationship between OH-PAHs and nine types of cancer (e.g., colorectal cancer, liver cancers, etc.). This study first emphasizes the causal cascade of individual OH-PAHs, vitamin D, and cancer risk, providing insights into prevention via the environment.

Global squid contamination by halogenated polycyclic aromatic hydrocarbons and its trade induced risk transfer

Squid is traded globally as an important food resource. However, the occurrence of carcinogenic halogenated polycyclic aromatic hydrocarbons (HPAHs) in squid and the risk of their transfer through trade is little understood or recognized. Here, we comprehensively evaluated the occurrence and risk transfer by quantifying the congener-specific concentrations of HPAHs in 121 squid samples collected from the Pacific, Atlantic and Indian oceans. This was the first time that nine of the 36 target chlorinated and brominated PAH congeners had been detected in squid. The HPAHs exhibited growth-dilution effects in the squid. The lipid content of squid was the most significant factor influencing HPAH bioaccumulation, while differences in squid growth and local ocean contamination influenced by geographical distribution also affected HPAH bioaccumulation. The redistribution and risk transfers of HPAHs in squid as a food could be affected by international trading. The cancer risks from squid consumption in China and Mexico were increased by 50 % and 30 %, respectively, because of international squid trading.

Environmental impacts of the widespread use of chlorine-based disinfectants during the COVID-19 pandemic

Chlorinated disinfectants are widely used in hospitals, COVID-19 quarantine facilities, households, institutes, and public areas to combat the spread of the novel coronavirus as they are effective against viruses on various surfaces. Medical facilities have enhanced their routine disinfection of indoors, premises, and in-house sewage. Besides questioning the efficiency of these compounds in combating coronavirus, the impacts of these excessive disinfection efforts have not been discussed anywhere. The impacts of chlorine-based disinfectants on both environment and human health are reviewed in this paper. Chlorine in molecular and in compound forms is known to pose many health hazards. Hypochlorite addition to soil can increase chlorine/chloride concentration, which can be fatal to plant species if exposed. When chlorine compounds reach the sewer/drainage system and are exposed to aqueous media such as wastewater, many disinfection by-products (DBPs) can be formed depending on the concentrations of natural organic matter, inorganics, and anthropogenic pollutants present. Chlorination of hospital wastewater can also produce toxic drug-derived disinfection by-products. Many DBPs are carcinogenic to humans, and some of them are cytotoxic, genotoxic, and mutagenic. DBPs can be harmful to the flora and fauna of the receiving water body and may have adverse effects on microorganisms and plankton present in these ecosystems.

Effects of microplastic sorption on microbial degradation of halogenated polycyclic aromatic hydrocarbons in water

Halogenated PAHs (HPAHs) are ubiquitous in the environment and have a toxicity similar to that of dioxin. Microplastics exist widely in the environment, and their sorption allows them to act as carriers of HPAHs, potentially changing the bioavailability of HPAHs. However, to the best of our knowledge related studies are limited. In this study, degrading bacteria of five HPAHs were cultivated from mangrove sediments. Among them, the Hyphomicrobium genus has good degradation ability on 9-BrAnt, 2-BrPhe and 2-ClPhe. The degradation process is in line with the first-order degradation kinetic characteristics. The kinetic equations of five kinds of HPAHs showed that the degradation half-lives are 0.65 days (2-BrFle), 0.79 days (9-ClPhe), 1.50 days (2-ClAnt), 5.94 days (9-BrPhe) and 14.1 days (9-BrAnt). The greater the number of benzene rings and the heavier the halogen substituents, the slower the degradation of HPAHs. The sorption of microplastics inhibited the biodegradation of HPAHs, and the degradation half-life of HPAHs will be extended from 0.65 to 14.1 days (the average is 4.59 days) to 1.71-9.93 days (average 5.40 days) for PA, 0.70-35.2 days (average 12.8 days) for PE, 6.02-28.2 (average 15.7 days) days for POM, and 4.60-24.0 (average 19.2 days) days for PP, which is mainly related to the partition coefficient between microplastics and water. This study provides a reference for reducing the uncertainty of the ecological risk assessment of HOCs in the aquatic environment.

Chlorinated Polycyclic Aromatic Hydrocarbons Induce Immunosuppression in THP-1 Macrophages Characterized by Disrupted Amino Acid Metabolism

Frequent chlorinated polycyclic aromatic hydrocarbon (Cl-PAH) occurrence in environmental samples and emerging detection in human serum have warned of their underestimated risks. Studies showed that some Cl-PAHs exhibit dioxin-like properties, implying immunotoxic potential but lacking direct evidence and specific mechanisms. Here, we integrated a high-content screening (HCS) system and high-resolution mass spectrometry to investigate the immune dysfunction and metabolic disruption induced by Cl-PAHs and their parent PAHs (PPAHs) in THP-1 macrophages. Both 9-chloroanthracene and 2,7-dichlorofluorene exerted clear immunosuppression on THP-1 mφs, while their PPAHs exhibited different immune disturbances. Interestingly, Cl-PAH/PPAHs induced complex alterations in the multicytokine/chemokine network, including biphasic alterations with initial inhibition and later enhancement. Furthermore, the protein-protein interaction results revealed that inflammatory cytokines are the core of this complicated network regulation. Connecting immune phenotypes and metabolomics, amino acid metabolism reprogramming was identified as a potential cause of Cl-PAH/PAH-induced immunotoxicity. Phytosphingosine and l-kynurenine were proposed as candidate immunosuppression biomarkers upon Cl-PAH exposure. This article provides direct immunotoxicity evidence of Cl-PAHs without activating AhR for the first time and discusses the contribution of metabolites to Cl-PAH/PPAH-induced immune responses in macrophages, highlighting the potential of developing new methods based on immunometabolism mechanisms for toxic risk evaluation of environmental chemicals.

Bioremediation of hazardous pollutants from agricultural soils: A sustainable approach for waste management towards urban sustainability

Soil contamination is perhaps the most hazardous issue all over the world; these emerging pollutants ought to be treated to confirm the safety of our living environment. Fast industrialization and anthropogenic exercises have resulted in different ecological contamination and caused serious dangerous health effects to humans and animals. Agro wastes are exceptionally directed because of their high biodegradability. Effluents from the agro-industry are a possibly high environmental risk that requires suitable, low-cost, and extensive treatment. Soil treatment using a bioremediation method is considered an eco-accommodating and reasonable strategy for removing toxic pollutants from agricultural fields. The present review was led to survey bioremediation treatability of agro soil by microbes, decide functional consequences for microbial performance and assess potential systems to diminish over potentials. The presence of hazardous pollutants in agricultural soil and sources, and toxic health effects on humans has been addressed in this review. The present review emphasizes an outline of bioremediation for the effective removal of toxic contaminants in the agro field. In addition, factors influencing recent advancements in the bioremediation process have been discussed. The review further highlights the roles and mechanisms of micro-organisms in the bioremediation of agricultural fields.

A novel hydrocyclone for use in underground DNAPL phase separation

Halogenated organic solvents are the most commonly detected pollutants in groundwater and are particularly toxic and harmful. How to separate these dense nonaqueous phase liquid (DNAPL) pollutants efficiently from groundwater has become an important research question. Here, a novel hydrocyclone with annular overflow structure was designed, which eliminated the short-circuit flow of the traditional hydrocyclone and solved the problem of overflow entrainment caused by the enrichment of droplets near the locus of zero vertical velocities (LZVV) into turbulence. The flow field characteristics of this novel hydrocyclone were studied using Computational Fluid Dynamics (CFD) simulation and compared with the traditional hydrocyclone. It was found that the annular gap structure of the novel hydrocyclone increased the tangential velocity of the outer vortex. Moreover, the radius of the LZVV was expanded outward by 0.17 mm, which reduced the possibility of droplets with small particle sizes in the second phase escaping from the overflow pipe. The collective effect was to eliminate the short-circuit flow. This novel hydrocyclone was able to separate DNAPL pollutants with low consumption and high efficiency, across a range of inlet velocity from 4 to 6 m/s. The maximum separation efficiency was 99.91 %. In addition, with trichloroethylene (TCE) as the target pollutant, the maximum volume fraction of the dispersed phase in the hydrocyclone was located on the side wall of the hydrocyclone. Taken together, we believe that this work will provide a low-cost, efficient separation method for the separation of groundwater- contaminated liquid mixtures. Furthermore, it has broad application prospects in the field of heterotopic remediation of groundwater.

Parent and Halogenated Polycyclic Aromatic Hydrocarbons in the Serum of Coal-Fired Power Plant Workers: Levels, Sex Differences, Accumulation Trends, and Risks

Workers in coal-fired power plants are at a high risk of exposure to polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (HPAHs), yet no studies have investigated such exposure of HPAHs. In this study, 12 PAHs and 8 chlorinated PAHs, but no brominated PAHs, were detected in >80% of serum samples from workers of a coal-fired power plant in eastern China. Serum HPAH concentrations were higher in plant workers (16-273 ng/g lipid) than in people without occupational exposure (12-51 ng/g lipid), and serum PAH and HPAH concentrations both in male and female workers were positively correlated with the occupational exposure duration, with an estimated doubling time of 11-17 years. Correlations were found between concentrations of ∑₈HPAHs and ∑₁₂PAHs but not between 7-chlorobenz[a]anthracene (7-ClBaA) and 1-chloropyrene (1-ClPyr) and their respective parent PAHs. In males, total concentrations of PAHs and HPAHs were positively correlated with pulmonary hypofunction and hypertension but not with abnormal electrocardiogram. The benzo[a]pyrene equivalents ratio of ∑₈HPAHs/∑₁₂PAHs was 0.3 ± 0.1. Among the HPAHs in the serum, 9-chlorophenanthrene, 7-ClBaA, and 1-ClPyr showed high health risks. This study is the first report on HPAH exposure in coal-fired power plant workers and provides new evidence on the health risks of PAHs and HPAHs in humans.

Potential Toxicity Risk Assessment and Priority Control Strategy for PAHs Metabolism and Transformation Behaviors in the Environment

In this study, 16 PAHs were selected as the priority control pollutants to summarize their environmental metabolism and transformation processes, including photolysis, plant degradation, bacterial degradation, fungal degradation, microalgae degradation, and human metabolic transformation. Meanwhile, a total of 473 PAHs by-products generated during their transformation and degradation in different environmental media were considered. Then, a comprehensive system was established for evaluating the PAHs by-products' neurotoxicity, immunotoxicity, phytotoxicity, developmental toxicity, genotoxicity, carcinogenicity, and endocrine-disrupting effect through molecular docking, molecular dynamics simulation, 3D-QSAR model, TOPKAT method, and VEGA platform. Finally, the potential environmental risk (phytotoxicity) and human health risks (neurotoxicity, immunotoxicity, genotoxicity, carcinogenicity, developmental toxicity, and endocrine-disrupting toxicity) during PAHs metabolism and transformation were comprehensively evaluated. Among the 473 PAH's metabolized and transformed products, all PAHs by-products excluding ACY, CHR, and DahA had higher neurotoxicity, 152 PAHs by-products had higher immunotoxicity, and 222 PAHs by-products had higher phytotoxicity than their precursors during biological metabolism and environmental transformation. Based on the TOPKAT model, 152 PAH by-products possessed potential developmental toxicity, and 138 PAH by-products had higher genotoxicity than their precursors. VEGA predicted that 247 kinds of PAH derivatives had carcinogenic activity, and only the natural transformation products of ACY did not have carcinogenicity. In addition to ACY, 15 PAHs produced 123 endocrine-disrupting substances during metabolism and transformation. Finally, the potential environmental and human health risks of PAHs metabolism and transformation products were evaluated using metabolic and transformation pathway probability and degree of toxic risk as indicators. Accordingly, the priority control strategy for PAHs was constructed based on the risk entropy method by screening the priority control pathways. This paper assesses the potential human health and environmental risks of PAHs in different environmental media with the help of models and toxicological modules for the toxicity prediction of PAHs by-products, and thus designs a risk priority control evaluation system for PAHs.

Short-Term Exposure Effects of the Environmental Endocrine Disruptor Benzo(a)Pyrene on Thyroid Axis Function in Zebrafish

Benzo(a)Pyrene (BaP) is one of the most widespread polycyclic aromatic hydrocarbons (PAHs) with endocrine disrupting properties and carcinogenic effects. In the present study, we tested the effect of BaP on thyroid development and function, using zebrafish as a model system. Zebrafish embryos were treated with 50 nM BaP from 2.5 to 72 h post fertilization (hpf) and compared to 1.2% DMSO controls. The expression profiles of markers of thyroid primordium specification, thyroid hormone (TH) synthesis, hypothalamus-pituitary-thyroid (HPT) axis, TH transport and metabolism, and TH action were analyzed in pools of treated and control embryos at different developmental stages. BaP treatment did not affect early markers of thyroid differentiation but resulted in a significant decrease of markers of TH synthesis (tg and nis) likely secondary to defective expression of the central stimulatory hormones of thyroid axis (trh, tshba) and of TH metabolism (dio2). Consequently, immunofluorescence of BaP treated larvae showed a low number of follicles immunoreactive to T4. In conclusion, our results revealed that the short-term exposure to BaP significantly affects thyroid function in zebrafish, but the primary toxic effects would be exerted at the hypothalamic-pituitary level thus creating a model of central hypothyroidism.

Ultrasensitive determination of 39 parent and emerging halogenated polycyclic aromatic hydrocarbons in human serum

Halogenated polycyclic aromatic hydrocarbons (HPAHs) have attracted extensive attention because of their high toxicity and bioaccumulation. However, there has been no report on the content of HPAHs in human tissues and the corresponding analytical method. In this study, a method for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) and 23 HPAHs in human serum was developed and validated. Simple and stable removal of interfering substances in complex serum and the detection of ultra-trace HPAHs are the key difficulties. After 0.5 mL serum was treated with formic acid and 10% isopropanol, samples were prepared by solid phase extraction (SPE) and analyzed by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The recoveries of the method were 65-103%, with low detection limits of 0.001-0.019 ng mL^-1. For HPAHs, the precision was in the range of 0.2-10% according to relative standard deviation (RSD). Subsequently, the developed method was validated for serum samples obtained in hospitals, and 8 PAHs and 12 HPAHs were detected. The concentration of ∑HPAHs was 23 ± 12 ng g^-1 lipid in females and 21 ± 10 ng g^-1 lipid in males, in which phenanthrene and anthracene halogenated derivatives were the main components. The level of HPAHs was correlated with PAHs, which was 23-119 times higher than that of HPAHs. The detected HPAHs contain highly toxic and persistent components, representing an ongoing human health risk, which should receive more attention.

Bromination mechanisms of aromatic pollutants: formation of Br2 and bromine transfer from metallic oxybromides

Bromination mechanisms of aromatic pollutants assume a chief contribution in the observed yields and pattern's distribution of a wide array of dioxin-like toxicants. However, salient features of the governing pathways remain largely speculative. This study presents detail mechanistic insights into two commonly discussed routes; namely: surface-assisted conversion of HBr into Br₂ and direct bromine transfer from oxybromides into a benzene ring. Utilizing iron surfaces, as structural representative of the metallic content in electronic wastes, results from density functional theory calculations portray accessible reactions into the successive dissociative adsorption of HBr over the Fe(100) surface and the subsequent evolution of gas phase bromine molecules. Activation energies for HBr uptake by the plain iron surface reside in the range of 129-182 kJ/mol. Over an oxygen pre-covered surface, dissociative adsorption of HBr leading to bromine molecules requires significantly lower activation energies (45-78 kJ/mol). Likewise, bromination of a benzene ring into a monobromobenzene molecule over Fe(100)_O*Br* (i.e., an oxybromide) configuration ensues with an opening activation energy of ~ 165 kJ/mol. Adsorption of a phenyl radical over an iron-oxybromide forms a phenolate moiety that subsequently desorbs from the surface into a phenoxy radical. Reaction pathways presented herein shall be useful in the ongoing efforts to comprehend the formation and bromination routes of the notorious bromine-bearing pollutants in real scenarios, such as, these encountered in the open burning and primitive thermal recycling of electronic wastes.

On the formation chemistry of brominated polycyclic aromatic hydrocarbons (BrPAHs)

Brominated polycyclic aromatic hydrocarbons (BrPAHs) have been consistently detected in various environmental matrices, and measured at alarming rates in stack emissions. However, formation mechanisms and bromination patterns of BrPAHs remain unclear. This contribution constructs detailed mechanistic pathways for the synthesis of selected BrPAHs (namely bromine-bearing naphthalene, acenaphthylene, anthracene, and phenanthrene). Mapped-out pathways follow the Bittner-Howard's route in the hydrogen abstraction acetylene addition (HACA) mechanism, in which a second C₂HBr molecule is added to the first one. Constructed kinetic model portrays temperature-dependent profiles of major and minor species. Direct loss of an H atom from the acetylenic fragment appears to be more important at elevated temperatures, when compared with further addition of C₂HBr cuts or ring-cyclization reactions. The occurrence of closed-shell Diels-Alder pathway should be inhibited owing to sizable enthalpic barriers. Fukui Indices for electrophilic substitutions (f^-1) establish bromination' s pattern of selected BrPAHs. The diradical character of BrPAHs coupled with electron-deficient C(Br) sites, render BrPAHs as potent precursors for the formation of environmentally persistent free radicals (EPFRs). Findings reported herein shall be useful in comprehending the formation chemistry of BrPAHs, a less-investigated category of toxicants in thermal systems.