Chlorinated and Brominated Polycyclic Aromatic Hydrocarbons from Metallurgical Plants

Occurrence of halogenated organic contaminants in surface sediments of the Yangtze River estuary and its adjacent marine area

Halogenated organic contaminants, such as chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs), are some of the most important emerging environmental pollutants. However, empirical data on Cl/Br-PAHs in estuarine and marine ecosystems are limited, rendering assessments of Cl/Br-PAH contamination in estuarine and offshore environments uncertain. Here the occurrence, sources, and ecological risks of 7 Cl-PAHs and 18 Br-PAHs were determined in surface sediments of the Yangtze River Estuary (YRE), a highly urbanized and industrialized area, and its adjacent marine area. The concentrations of Cl-PAHs ranged from 4.50 to 18.38 ng g-1 (average 7.19 ng g-1), while those of Br-PAHs ranged from 4.80 to 61.18 ng g-1 (average 14.11 ng g-1). The dominant Cl-PAH and Br-PAH in surface sediment were 9-chlorofluorene (17.79%) and 9-bromofluorene (58.49%), respectively. The distributions and compositions of Cl/Br-PAHs in the surface sediments varied considerably due to complex hydrodynamic and depositional conditions in the YRE and its adjacent marine area, as well as differences in physicochemical properties of different Cl/Br-PAHs. Positive matrix factorization revealed that the primary sources of Cl/Br-PAHs in the study area were e-waste dismantling (33.6%), waste incineration (23.2%), and metal smelting (11.0%). According to the risk quotient, the Cl/Br-PAHs in sediments posed no toxic risk to aquatic organisms.

Identification and seasonal variation of specific particulate bound (halogenated) polycyclic aromatic hydrocarbons in air from different metal industrial parks in Northwest China

During the process of industrial heating, a large amount of polycyclic aromatic hydrocarbons (PAHs) and their halogenated compounds (Cl/Br-PAHs) can be formed. However, there is still limited understanding of the chemicals from different metal smelting industrial parks. This study evaluated the seasonal variations, composition profiles, and source allocations of the atmospheric particulate-bound PAHs and Cl/Br-PAHs in different metal industrial parks in a typical industrial city in northwest China. The results showed that the main PAHs produced by metal smelting were low molecular weight isomers, and the concentrations of Cl-PAHs were lower compared to Br-PAHs. The main Br-PAHs were 1-Br-Pyr and 4-Br-Pyr, while 9-Cl-Fle, 1-Cl-Pyr, and 6-Cl-BaP were the dominated Cl-PAH isomers. No significant difference was found in the concentrations among the sites, whereas the levels of the target chemicals were higher during cold months compared to warm months. The main source of PAHs was coal combustion and gasoline vehicle emission during metal smelting, and that of Cl/Br-PAHs was also industrial coal burning. In addition to the primary source, the secondary chlorination of parent PAHs was also a significant source of Cl-PAHs in the production of high purity aluminum. This study suggests that Cl-PAHs and Br-PAHs may behave differently in the atmosphere.

Atmospheric occurrences and bioavailability health risk of PAHs and their derivatives surrounding a non-ferrous metal smelting plant

Non-ferrous metal smelting emits large amounts of organic compounds into the atmosphere. Herein, 20 parent polycyclic aromatic hydrocarbons (PPAHs), 9 nitrated PAHs (NPAHs), 14 chlorinated PAHs (ClPAHs), and 6 alkylated PAHs (APAHs) in atmospheric samples from a typical non-ferrous metal smelting plant (NMSP) and residential areas were detected. In NMSP, benzo[a]pyrene, dibenz[a,h]anthracene, 6-nitrochrysene, 9-chlorofluorene, and 1-methylfluorene were the predominant compounds in the particulate phase, while phenanthrene constituted 57.3% in the gaseous phase. The concentration of PAHs in residential areas around NMSP was 1.8 times higher than that in the control area. Additionally, there was a significant negative correlation between the concentration and the distance from the NMSP. In terms of health risks, although the skin penetration coefficient of PM2.5 is smaller than that of the gaseous phase, dermal absorption of PM2.5 posed a greater threat to the population, the incremental lifetime cancer risk (ILCR) of NMSP was 1.8 × 10-4. After considering bioavailability, BILCR decreased by 1-2 orders of magnitude in different regions, and dermal absorption decreased more than inhalation intake. Nevertheless, the dermal absorption of PM2.5 in NMSP still presents a probable carcinogenic risk. This study provides a necessary reference for the subsequent control of NMSP contamination.

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

Collapse

MESH Headings

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

Collapse

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.

Collapse

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.

Halogenated polycyclic aromatic hydrocarbons in Chinese traditional sausages with high salt: Profiles in market samples and formation during home cooking

Halogenated polycyclic aromatic hydrocarbons (XPAHs) are likely to be generated by the reaction between polycyclic aromatic hydrocarbons (PAHs) and halide ions and therefore pose a great threat to high salt food safety. The aim is to explore the profiles of PAHs/XPAHs in market sausages and their formation during home cooking. Concentrations of PAH24 and XPAH18 in 36 market samples were 5.18-408.52 μg/kg and 0.05-0.41 μg/kg, respectively. Smoked sausages exhibited significantly higher concentrations of PAHs than non-smoked sausages. While ready-to-eat sausages presented notably higher XPAH levels than raw sausages. Furthermore, overcooking, such as baking at 220 °C, could result in an exaggerated increase in PAHs. Meanwhile, the increased chlorinated PAH levels after cooking indicated the unintentional formation of XPAHs during sausage cooking. Based on the ILCR model, the intake of 12.7 g/d for males and 10.8 g/d for females is the maximum threshold to achieve negligible risk levels (10-6).

Atmospheric occurrences and health risk assessment of polycyclic aromatic hydrocarbons and their derivatives in a typical coking facility and surrounding areas

Coking facilities release large quantities of polycyclic aromatic hydrocarbons (PAHs) and their derivatives into the ambient air. Here we examined the profiles, spatial distributions, and potential sources of atmospheric PAHs and their derivatives in an industrial coking plant and its surrounding environment (gaseous and particulate). The mean concentrations of PAHs, nitrated PAHs (NPAHs), chlorinated PAHs (ClPAHs), and brominated PAHs (BrPAHs) in the air of the coking facility were 923, 23.8, 16.7 and 4.25 ng m-³, respectively, 1-2 orders of magnitude higher than those in the surrounding area and the control area. Linear regressions between contaminant concentrations and distance from the coking facility suggested that the concentrations of PAHs (r2 = 0.82, p < 0.05), NPAHs (r2 = 0.77, p < 0.01), and BrPAHs (r2 = 0.62, p < 0.01) were negatively correlated with distance. Additionally, the particle-bound fractions of PAHs and their derivatives were significantly correlated with their molecular weights (p < 0.01). Based on the calculation of the gas/particle partitioning coefficients (log KP) for PAHs and their derivatives and the corresponding subcooled liquid vapor pressures (log PL), the slope values for PAHs, NPAHs, ClPAHs, and BrPAHs ranged from -1 to -0.6, indicating that deposition of PAHs and their derivatives occurred through both adsorption and absorption. Five emissions sources were identified by positive matrix factorization (PMF), including coking emissions, oil pollution, industrial and combustion sources, secondary formation, and traffic emissions, with coking emissions accounting for more than 50% of total emissions. Furthermore, the results of the health risks assessment suggested that atmospheric PAHs and their derivatives in the coke plant and surrounding area negatively impacted human health.

Spatiotemporal variability of PAHs and their derivatives in sediments of the Laizhou Bay in the eastern China: Occurrence, source, and ecological risk assessment

To understand the pollution status and risk levels in the Laizhou Bay, the spatiotemporal distribution, source, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs) and 20 substituted PAHs (SPAHs) were studied in surface sediments in 2022. The findings indicated significant seasonal differences in the concentrations of PAHs and SPAHs under the influences of precipitation, temperature, light, and human activities, with higher storage levels in summer than in spring, and there was also a spatial distribution trend of estuary > coast > offshore. 2-Nitrofluorene (2-NF) and 2-methylnaphthalene (2-MN) were the most abundant components of SPAHs in both spring and summer, with levels of 21.44 ng/g and 17.89 ng/g in spring, 43.22 ng/g and 25.51 ng/g in summer, respectively. The results of the diagnostic ratio and principal component analysis - multiple linear regression identified sources of PAHs and SPAHs as combustion sources, including petroleum, coal, and biomass. The risk level of PAHs was low-to-moderate according to the toxicity equivalent quotient (TEQ) and risk quotient. A novel calculation method based on TEQ was proposed to assess the ecological risk of SPAHs, and the results indicated that the risk level of SPAHs was moderate-to-high.

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.

The last 50 years of organic contamination of a highly anthropized tributary of the Po River (Italy)

We examined the temporal profiles of many organic micropollutants analysed in a sediment core sampled from a highly anthropized tributary of the Po River, the Lambro River. Analysed for extractable organic halogens (EOX), total petroleum hydrocarbons (C₁₀-C₄₀TPH), polycyclic aromatic hydrocarbons (PAHs), common legacy pollutants (DDTs, PCBs), halogenated flame retardants (PBDEs, DBDPE, TBBPA-bis, TCBPA, TBBPA, HBCDs), organotins (TBT, TPhT), antimicrobials (TCS, TCC), fragrances (AHTN, HHCB) and phthalates (DMP, DEP, DnBP, BBP, DEHP, DnOP), the dated sediment core revealed the historical record of 50 years of chemical contamination discharged into the Lambro and thereby the Po River. In this regard, the peak levels of PCBs and DDTs found in Lambro sediments were also identified in other sediment cores collected from the Po River prodelta in the Adriatic Sea, thus hundreds of kilometres downstream (Combi et al., 2020). The highest risk to aquatic organisms was associated with decades of high levels of C₁₀-C₄₀ TPH, PBDEs, PCBs, PAHs, DDTs, EOX, TCC, AHTN and DEHP, which in different periods of the contamination history, showed exceedances of guideline/threshold values. C₁₀-C₄₀ TPH and TCC, for example, were very high in the 1960s, whereas PCBs, DDTs, and PBDEs, peaked from the 1980s onward. The corresponding sums of PEC quotients ranged between 0.48 and 28.63, with a mean value (±SD) for the entire recording period of 10.62 ± 9.83. Environmental legislations and improved wastewater treatments were the main drivers of the recent downward trends observed for most of the chemicals investigated. Floods in turn resulted in macroscopic yet temporary improvements in the chemical quality of the tributary, conveying contaminated sediments into the Po River.

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.

Levels, profiles and potential human health risks of brominated and parent polycyclic aromatic hydrocarbons in soils around three different types of industrial areas in China

Brominated polycyclic aromatic hydrocarbons (Br-PAHs) are an emerging class of persistent organic pollutants with toxicity similar to dioxins. Industrial thermal processes have been identified as major sources of Br-PAHs in the current environment. However, studies on soil contaminations with Br-PAHs around industrial areas were scarce. In this study, 18 Br-PAHs and 16 PAHs were analyzed in soils around an electronic waste dismantling area (EDA), an industrial area that mainly performed steel smelting (SSP), and an industrial area mainly performed secondary copper smelting (SCS). The mean concentrations of Br-PAHs and PAHs were 1362 pg/g and 1034 ng/g, 582 pg/g and 13,938 ng/g, and 307 pg/g and 2211 ng/g in the soil around EDA, SSP, and SCS, respectively. The order of Br-PAH concentrations among three industrial areas was inconsistent with that of PAHs, suggesting that there may be some differences in contamination characteristics of Br-PAHs in three types of industrial areas. The significant correlation between Br-PAHs and parent PAHs indicated that direct bromination may be the main formation pathway of Br-PAHs in soils in EDA. The result of principal component analysis further revealed that the congener pattern of Br-PAHs in soils around EDA is different from that of SSP and SCS. It was found that the ratio of 1-BrPyr and 3-BrFlu can be applied to identify environmental contamination with Br-PAHs from e-waste dismantling. The health risk assessment results showed that there were some soil samples with carcinogenic risks above the risk threshold in each industrial area, and deserve our concern.

Metal-Catalyzed Formation of Organic Pollutants Intermediated by Organic Free Radicals

Metal compounds play important roles in the formation of organic pollutants during thermal-related processes. However, the metal-catalyzed predominant organic pollutants have not previously been characterized nor have any detailed catalytic mechanisms been clarified. Here, we preciously distinguished the multiple organic free radical intermediates on metal catalyst surfaces during the organic pollutant formation through laboratory and theoretical studies. Differences between the organic free radical intermediate species, concentrations, and formation mechanisms under the catalysis of different metal compounds were investigated. The results were verified mutually with the differed characteristics of organic pollutant products. CuO predominantly catalyzed the formation of highly chlorinated phenoxy radical intermediates and dioxins. High proportions of semiquinone radicals and oxygen-containing derivatives were found on ZnO surfaces. Differently, methyl-substituted phenoxy radicals and long-chain products formed on Al₂O₃ surfaces. The results will be instructive for the target emission control of priority organic pollutants during thermal-related processes rich in different metal compounds.

Prediction study on the distribution of polycyclic aromatic hydrocarbons and their halogenated derivatives in the atmospheric particulate phase

Polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (X-PAHs), which generally produced from photochemical and thermal reactions of parent PAHs, widely exist in the environment. They are semi-volatile organic chemicals (SVOCs) and the partitioning between gas/particulate phases affects their environmental migration, transformation and fate, which further impacts their toxicity and health risk to human. However, there is a large data missing of the experimental distribution ratio in the atmospheric particulate phase (f), especially for X-PAHs. In this study, we first checked the correlation between experimental f values of 53 PAH derivatives and their octanol-air partitioning coefficients (log K_OA), which is frequently used to characterize the distribution of chemicals in organic phase, and yielded R² = 0.803. Then, quantum chemical descriptors derived from molecular structural optimization by M06-2X/6-311 +G (d,p) method were further employed to develop Quantitative Structure-Property Relationship (QSPR) model. The model contains two descriptors, the average molecular polarizability (α) and the equilibrium parameter of molecular electrostatic potential (τ), and yields better performance with R² = 0.846 and RMSE = 0.122. The mechanism analysis and validation results by different strategies prove that the model can reveal the molecular properties that dominate the distribution between gas and particulate phases and it can be used to predict f values of other PAHs/X-PAHs, providing basic data for their environmental ecological risk assessment.

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 and current practices of recycling waste printed circuit boards: A review of the recent progress in pyrometallurgy

Over the last few decades, a substantial amount of e-waste including waste printed circuit boards (WPCBs) has been produced and is accumulating worldwide. More recently, the rate of production has increased significantly, and this trend has raised some serious concerns regarding the need to develop viable recycling methods. The presence of other materials in the WPCBs, such as ceramics and polymers, and the multi-metal nature of WPCBs all contribute to the increased complexity of any recycling process. Among the viable techniques, pyrometallurgy, with the inherent ability to process the waste independent of its composition, is a promising candidate for both rapid and large-scale treatment. In the present study, firstly, the principles of the pyrometallurgical methods for WPCB recycling are discussed. Secondly, the different unit operations of thermochemical pretreatment including incineration, pyrolysis, and molten salt processing are reviewed. Thirdly, the smelting processes for the recovery of metals from WPCBs, as well as the issues surrounding slag formation and subsequent treatment are explained. Fourthly, alternative methods for the recovery of polymers and ceramics, in addition to metal recycling, are elucidated. Fifthly, emission control techniques and the potential for energy recovery are evaluated.

Insights into the hepatotoxicity of pyrene and 1-chloropyrene using an integrated approach of metabolomics and transcriptomics

The toxicity of pyrene (Pyr) and its chlorinated species have not be comprehensively and clearly elucidated. In this study, an integrated approach of metabolomics and transcriptomics were applied to evaluate the hepatotoxicity of Pyr and 1-chloropyrene (1-Cl-Pyr) at human exposure level, using human L02 hepatocytes. After 24 h exposure to Pyr and 1-Cl-Pyr at 5-500 nM, cell viability was not significantly changed. Transcriptomics results showed that exposure to Pyr and 1-Cl-Pyr at 5 and 50 nM obviously altered the gene expression profiles, but did not significantly induce the expression of genes strongly related to the activation of aryl hydrocarbon receptor (AhR), such as CYP1A1, CYP1B1, AHR, ARNT. Pyr and 1-Cl-Pyr both induced a notable metabolic perturbation to L02 cells. Glycerophospholipid metabolism was found to be the most significantly perturbed pathway after exposure to Pyr and 1-Cl-Pyr, indicating their potential damage to the cell membrane. The other significantly perturbed pathways were identified to be oxidative phosphorylation (OXPHOS), glycolysis, and fatty acid β oxidation, all of which are related to energy production. Exposure to Pyr at 5 and 50 nM induced the up-regulation of fatty acid β oxidation and OXPHOS. The similar result was observed after exposure to 5 nM 1-Cl-Pyr. In contrast, exposure to 50 nM 1-Cl-Pyr induced the down-regulation of OXPHOS by inhibiting the activity of complex I. The obtained results suggested that the modes of action of Pyr and 1-Cl-Pyr on energy production remarkably varied not only with molecular structure change but also with exposure concentration.

Discovery of significant atmospheric emission of halogenated polycyclic aromatic hydrocarbons from secondary zinc smelting

Chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are emerging persistent organic pollutants. Current knowledge on the emissions of Cl/Br- PAHs is far insufficient for source control, much less on their formation mechanisms. In this field study, Cl/Br-PAHs formation mechanisms were proposed from the macro perspective of practical secondary metal smelting industries. We found secondary zinc smelting as a significant source of Cl/Br-PAHs (9553 ng/m³ in stack gas), exceeding concentrations from other metal smelting sources by 1-2 orders of magnitude. Cl/Br-PAH emission characteristics differed between various secondary metal smelting processes, indicating dominance of different formation mechanisms. Cl/Br-PAHs with fewer rings were dominant from secondary zinc smelting and secondary copper smelting. Differently, emissions from secondary aluminum smelting were dominated by congeners with more rings. The differences in congener profiles were attributable to the catalytic effects of metal compounds during smelting activities. Zinc oxide and copper oxide dominantly catalyzed dehydrogenation reactions, contributing to the formation of intermediate radicals and subsequent dimerization to Cl/Br-PAHs with fewer rings. Differently, aluminum oxide induced alkylation reactions and accelerated ring growth, resulting in the formation of Cl-PAHs with more rings. The newly proposed mechanisms can successfully explain the emission characteristics of Cl/Br-PAHs during smelting activities, which should be important implication for Cl/Br-PAHs targeted source control.

p-Phenylenediamine Antioxidants in PM2.5: The Underestimated Urban Air Pollutants

The wide use and continuous abrasion of rubber-related products appears to be leading to an incredible release of p-phenylenediamine (PPD) antioxidants in the environment. However, no related research has been conducted on the pollution characteristics and potential health risks of PM_2.5-bound PPDs. We report for the first time the ubiquitous distributions of six emerging PPDs and a quinone derivative, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPDQ), in PM_2.5 from urban areas of China. Atmospheric contamination levels of PM_2.5-bound PPDs were found to be mostly in pg m^-3 amounts between 2018 and 2019. Urban vehicle rubber tire abrasion was found to probably contribute to the PPDs in PM_2.5 and accounted for their significant spatiotemporal-dependent concentration variations. Furthermore, 6PPDQ, an emerging oxidation product of 6PPD in the environment, was first quantified (pg m^-3) with a total detection rate of 81% in the urban PM_2.5, demonstrating its broad existence. On the basis of the determined ambient concentrations, the annual intakes of PPDs and 6PPDQ for adults were not low, indicating their possible human health risks induced by long-term exposure. This study confirms the widespread occurrence of PPDs and 6PPDQ in PM_2.5, showing that the pollution of such compounds in urban air should not be underestimated.

Spatial and temporal variation, source identification, and toxicity evaluation of brominated/chlorinated/nitrated/oxygenated-PAHs at a heavily industrialized area in eastern China

Some derivatives of polycyclic aromatic hydrocarbons (PAHs) such as chlorinated and brominated PAHs (Cl/BrPAHs), nitrated and oxygenated PAHs (N/OPAHs) have attracted significant concern due to their high toxicity. Knowledge of the profiles, formation mechanisms, and potential sources of these toxic chemicals near the industrial complexes is essential for their pollution control and management. In this study, we monitored Cl/BrPAHs, N/OPAHs, and PAHs at 24 sampling sites near a heavily industrialized area (steel, chemical, and rubber plants) using passive air samplers during the heating period (7 December 2019 to 15 April 2020) and the non-heating period (2 June 2020 to 4 October 2020). The total average concentrations of 16 BrPAHs, 8 ClPAHs, 17 NPAHs, 6 OPAHs, and 18 PAHs during both sampling periods were 471 pg/m³, 229 pg/m³, 312 pg/m³, 2120 pg/m³, and 63.1 ng/m³, respectively. Except for NPAHs, BrPAHs, ClPAHs, OPAHs, and PAHs all showed higher levels during the heating period. The spatial distributions of Cl/BrPAHs, N/OPAHs, and PAHs exhibited a similar pattern, with the highest concentrations detected in the vicinity of the steel industry. Congener profiles of PAH derivatives indicated that mono-substituted low molecular weight compounds (2-3 rings) were dominant. The major formation mechanisms of halogenated PAHs were discussed by correlation analysis and relative Gibbs free energies, and direct bromination of parent PAHs could be the major formation mechanism of BrPAHs in this study. Diagnostic ratios showed that NPAHs were mainly derived from primary emissions, but the contribution of secondary formation was increased at heavily contaminated sites. The positive matrix factorization model extracted four Cl/BrPAHs, three N/OPAHs, and four PAHs factors, and the result showed that PAHs and their derivatives mainly derived from industrial and combustion sources, photochemical reactions, vehicle emissions, and crude oil volatilization, etc.

Contribution of atmospheric deposition to halogenated polycyclic aromatic hydrocarbons in surface sediments: A validation study

Surface sediments are both sinks and sources of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) in the environment. It is important to study the source of Cl/Br-PAHs in the surface sediment for controlling the ecological risk of Cl/Br-PAHs. Clues from the previous research suggested that atmospheric deposition may be one of the main sources of Cl/Br-PAHs in sediment. However, due to the lack of matched sediment and atmospheric Cl/Br-PAHs data, the contribution of atmospheric deposition to Cl/Br-PAHs in sediment has not been confirmed. This study investigated the characteristics of 37 Cl/Br-PAHs and validated the contribution of atmospheric sedimentation to Cl/Br-PAHs in sediment by a case study in the surface sediments of the Chaobai River, China. To the best of our knowledge, four Cl-PAHs and eleven Br-PAHs were found in the sediments for the first time. The total concentrations of 18 Cl-PAH species were 76-2301 pg/g, while those of Br-PAHs were 6-238 pg/g. The toxic equivalent quantities (TEQ) of the Cl-PAHs in surface sediments in the water conservation area and in the urban comparison area were 0.73 pg TEQ/g and 2.21 pg TEQ/g, respectively. The TEQ of the Br-PAHs in surface sediments in the water conservation area and in the urban comparison area were 2.85 × 10^-2 pg TEQ/g and 6.6 × 10^-2 pg TEQ/g, respectively. Based on the characteristics comparison and correlation analysis of Cl/Br-PAHs in both sediment and ambient air, it was initially confirmed the contribution of atmospheric deposition to Cl-PAHs in sediments. However, there was no conclusion of Br-PAHs in sediment similar to Cl-PAHs in sediment. It was inferred that the sources of Br-PAHs in sediment were different from Cl-PAHs in sediment.

Transcriptomics and metabolomics analyses provide insights into the difference in toxicity of benzo[a]pyrene and 6-chlorobenzo[a]pyrene to human hepatic cells

The toxicological information of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs), as derivatives of PAHs, is still relatively lacking. In this study, a combination of transcriptomics and metabolomics approach was adopted to explore the changes in toxicity to human L02 hepatocytes after chlorination of benzo[a]pyrene (B[a]P) at 6 position. In general, 6-Cl-B[a]P produced a stronger toxicity to human hepatic cells than did parent B[a]P. When exposure concentrations were 5 and 50 nM, 6-Cl-B[a]P caused a weaker transcriptomic perturbation relative to B[a]P, whereas a stronger metabolomic perturbation, a stronger oxidative stress and a stronger inhibition effect on cell viability were caused by 6-Cl-B[a]P than did parent B[a]P. Pathway enrichment analysis indicated that 6-Cl-B[a]P produced a more widely perturbation to metabolic pathways than did B[a]P. Although they both significantly impaired the function of mitochondrial electron transport chain (ETC), the exact mechanism is different. B[a]P suppressed the expression of 20 genes regulating mitochondrial ETC mainly via AhR activation. However, 6-Cl-B[a]P produced a stronger inhibition on the activities of complexes I and V than did B[a]P. Meanwhile, 6-Cl-B[a]P also exhibited a stronger inhibition effect on mitochondrial β oxidation of fatty acid. Furthermore, 6-Cl-B[a]P and B[a]P both significantly disturbed the nucleotide metabolism, glycerophospholipid metabolism and amino acid metabolism in L02 cells.

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.

Congener profiles and process distributions of polychlorinated biphenyls, polychlorinated naphthalenes and chlorinated polycyclic aromatic hydrocarbons from secondary copper smelting

Secondary copper smelting is an important industrial source of unintentionally produced persistent organic pollutants (UPOPs) emissions. Herein, field study on industrial-scale plants was conducted to clarify the levels and profiles of polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and chlorinated polycyclic aromatic hydrocarbons (> 3 rings, Cl-PAHs) from secondary copper smelting plants. The three UPOPs emission levels from the oxygen-enriched smelting furnace were higher than that from the anode furnace, which was attributed to the low-grade raw materials used. The toxic equivalent quantity concentrations of Cl-PAHs were 1.3-4.4 and 4.6-18.9 times higher than that of PCBs and PCNs, respectively. Thus, the emission control of Cl-PAHs in the secondary copper industry should be of concern. The chlorination degree of PCBs and PCNs was ~4 after the gas-cooling stage but was reduced to 1-2 in the stack outlet. This result indicated that the PCBs and PCNs congeners that were generated during the cooling stage were mainly higher-chlorinated. After purification by air pollution control devices (APCDs), the high-chlorinated congeners were removed simultaneously with the fly ash, whereas the low-chlorinated congeners may be regenerated and transferred into the stack gas due to possible memory effect within the APCDs.

Occurrence of chlorinated and brominated polycyclic aromatic hydrocarbons from electric arc furnace for steelmaking

Chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are persistent organic pollutants with potential carcinogenic toxicities that are even higher than those of their parent PAH congeners. Current knowledge of Cl/Br-PAH sources and emission characteristics is lacking. Electric arc furnace (EAF) steelmaking is a potential source for Cl/Br-PAHs, considering that preheating of raw materials before they enter the EAF could produce suitable conditions for Cl/Br-PAHs formation. In this field study, we identified EAFs as an important source of Cl/Br-PAHs and clarified their emission concentrations, fingerprints by gas chromatography coupled with high-resolution magnetic mass spectrometry. Potential formation mechanisms of Cl/Br-PAHs were also proposed. The mass concentration ranges for Σ₁₈Cl-PAHs and Σ₁₈Br-PAHs in stack gas were 25.85-4191 ng Nm^-3 and 1.02-341 ng Nm^-3, respectively. The variation of concentration indicated that the steel scrap composition greatly affected the production of Cl/Br-PAHs. The congener ratios including 6-chlorobenzo [a]pyrene/3-chlorofluoranthene and 1-chloroanthracene/1-chloropyrene could be used to estimate the influence of industrial sources on Cl-PAH occurrences in the air. Ring structure growth was the dominant formation pathway for Cl/Br-PAHs, distinctly different from dioxin formation mechanisms dominated by precursor dimerization and chlorination.

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

Halogenated polycyclic aromatic hydrocarbons (HPAHs) are high lipophilic and degradation-resistant, which have been detected in the air, water, sediment and biota. HPAHs tend to have strong adverse effects on animals and humans. Although we have realized HPAHs are emerging contaminants which needs to be paid attention, there is still a lack of their individual commercial standards. This makes it difficult for understanding HPAHs comprehensively. This review is devoted to collect all the results have reported, and give a systemic look of their global distributions, influence factors and sources. Compared with air, studies on other environmental matrices (water and sediment) are more limited. The researches on organisms are fewest. Comparing the studied congeners, there are more studies on ClPAHs than BrPAHs. Human activities contribute mostly to their occurrence. Further, we then also introduce the toxicity and analytical methods to better understand HPAHs. The future research directions are also provided. Through this review, we can conclude there is an urgent need to develop analysis methods and ecologic risk assessment for better exploring HPAHs. Effective methods should be done to control HPAHs. Therefore, this review can provide a good basis for researchers to understand and control global pollution.

Accurate and ultrasensitive determination of 72 parent and halogenated polycyclic aromatic hydrocarbons in a variety of environmental samples via gas chromatography-triple quadrupole mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (XPAHs) are ubiquitous in various environmental media. Analytical problems, however, make it difficult to accurately determine their concentrations. To develop a satisfactory analytical method suitable for a diversity of PAHs and XPAHs in multiple environmental samples, we evaluated three commercial analytical columns (DB-5MS, Select PAH, and Rxi-PAH) for better chromatographic separation and optimized the analytical conditions for gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). Comparison of the abilities of the columns to separate peaks revealed that the Rxi-PAH was the best column for both PAH and XPAH analyses. Optimization of analytical conditions for GC-MS/MS resulted in sensitivities for PAHs and XPAHs that were 4.2-fold-2600-fold higher than the sensitivities of GC-high-resolution MS (GC-HRMS) (an example of a traditional analytical method). Although there were no statistically significant differences between the instrumental detection limits (IDLs) of PAHs and XPAHs measured by GC-HRMS, the IDLs of XPAHs were significantly lower than those of PAHs when measured by GC-MS/MS. This difference could be attributed to the unique ionization patterns of XPAHs in the GC-MS/MS analysis, which suppressed background noise and increased the analytical sensitivity. Analyses of PAHs and XPAHs in grilled chicken, vehicle exhaust, sea sediment, ambient air, and indoor dust via the analytical method optimized in this study revealed that the proposed method was sufficiently sensitive, comprehensive, and versatile for risk assessment purposes, and could eliminate interferences associated with the co-elution of target PAHs and XPAHs.

Characterization of Mining-Related Aromatic Contaminants in Active and Abandoned Metal(loid) Tailings Ponds

This study reports on the compositional diversity of organic compounds in metal(loid)-bearing tailings samples from both active and abandoned tailings ponds. Tailings samples were qualitatively analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS). In addition, the priority PAHs (16), PAEs (6), and phenols (2) were quantitatively analyzed using gas chromatography-mass spectrometry (GC-MS). We attribute the presence of some of aromatic organics in studied tailings ponds to particular sources. Mineral floatation reagents are likely the major sources of small-ring aromatics in tailings ponds, and products from metallurgical processing and burning of fossil fuels in the mining area or further afield are also possible contributors and might be the main source of large-ring aromatics. We found that tailings ponds abandoned for decades can still have organics concentrations at levels of concern. Large-ring aromatics are generally more toxic than other contaminants, and these were more abundant in abandoned tailings ponds. This suggests that these large-ring organics do not readily decompose or biodegrade into less toxic byproducts, as do volatiles and many other organic compounds. Our aromatic contaminants database provides an important starting point for researchers to investigate and compare similar contaminants that might be also present in other tailings ponds and emphasizes the necessity of considering their transformations over time.

Field study of PAHs with their derivatives emitted from e-waste dismantling processes and their comprehensive human exposure implications

Extensive electronic waste (e-waste) recycling might be an important emission source of polycyclic aromatic hydrocarbons (PAHs) mixture, which might induce negative effects on the employees. In the present work, atmospheric pollution patterns of PAHs and their derivatives were determined in five different workshops to dismantle waste printed circuit boards (WPCBs) via thermal treatment. The results showed that mass concentrations of PAHs, chlorinated PAHs (ClPAHs), brominated PAHs (BrPAHs), oxy-PAHs (OPAHs) as well as carbazole (CBZ) were ranged from 1.53 × 10⁴-2.02 × 10⁵, 32.3-364, 8.29-1.13 × 10³, 923-1.39 × 10⁴ and 225-1.95 × 10³ pg·m^-3, respectively. Electric heating furnaces (EHF) workshops emitted relatively higher contaminants than other disposal sectors. OPAHs was found to be the most predominant derivatives of PAHs with 9,10-anthraquinone (83.0%) has the absolute superior in EHFTV, while benzo(a)anthracene-7,12-dione (>45.0%) was found to be the highest congener in other workshops, respectively. 9,10-Cl₂Phe exhibited the largest contributions to the ΣClPAHs whereas the composition profiles of BrPAHs varied among five workshops. In addition to direct chlorination of parent PAHs, thermal degradation of halogenated flame retardants incorporated into plastic materials might dominate the generation of Cl/BrPAHs from e-waste dismantling activities. The specific isomeric ratios of BrPAHs (3-BrFlu/1-BrPyr and 1-BrPyr/3-BrFlu) might be used to discriminate other emission sources from pyrolysis of WPCBs. However, their specific application as novel tracers for source identification should be further verified with more studies. The emitted PAHs mixture with their derivatives in all dismantling workshops posed carcinogenic risks to these dismantling workers via inhalation, particularly the workshop using electric heating furnaces to treat router. Nevertheless, new loadings of PAHs derivatives observed from e-waste dismantling activities, as well as their comprehensive health risk assessment provides us with a fresh perspective on the source appointment and potential adverse consequences of PAHs. More attention needs to be paid to the potential carcinogenic risks of exposure to PAHs and their derivatives from e-waste dismantling processes.

Characteristics of chlorinated and brominated polycyclic aromatic hydrocarbons in the Pearl River Estuary

The spatial distribution of halogenated polycyclic aromatic hydrocarbons (H-PAHs) (8 chlorinated PAHs (Cl-PAHs) and 9 brominated PAHs (Br-PAHs)), in the Pearl River Estuary (PRE) was investigated. The total concentrations of 17H-PAHs in sediment samples were ranged from 1.4 ng g^-1 to 40.9 ng g^-1 with an average concentration of 14.7 ng g^-1. The average H-PAH concentration in the suspended particulate matters (SPMs) (475.6 ng g^-1) was 30 times higher than that in the sediments (14.7 ng g^-1), and H-PAHs were rarely detected in the aqueous phase. The dominant H-PAHs in sediments were 9,10-dichloroanthracene (31.2%) and 9-chlorophenanthrene (32.0%); 2/9-chlorofluorene (27.4%) was prominent in surface SPMs, while no significant dominant congeners were found in bottom SPMs. Principal component analysis showed that the congener profiles of H-PAHs in sediments were different from those of SPMs especially for surface SPM samples which might be caused by point source discharges of H-PAHs from the coast of the PRE. In general, riverine inputs were the major source of H-PAHs in the PRE, and SPMs were important carriers for transporting H-PAHs. Diagnostic analyses showed that the H-PAHs might originate from waste incineration and automobile emissions in the Pearl River Delta (PRD).

The pollution profiles and human exposure risks of chlorinated and brominated PAHs in indoor dusts from e-waste dismantling workshops: Comparison of GC-MS, GC-MS/MS and GC × GC-MS/MS determination methods

The toxicities of some chlorinated and brominated polycyclic aromatic hydrocarbons (X-PAHs) are higher than their corresponding parent PAHs. However, the identification and quantitation of X-PAHs in environment are still changeable and limitedly reported. To develop a robust method for routine analysis of X-PAHs in environmental samples, the determination of 34 X-PAHs was performed and compared using different instruments, including gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS/MS) in both electron ionization (EI) and negative chemical ionization (NCI) modes, and comprehensive two-dimensional gas chromatograph-tandem mass spectrometer (GC × GC-MS/MS). GC-EI-MS/MS possessed the highest sensitivity with method detection limits of 2.00-40.0 and 2.00-20.0 pg/g dry weight (dw) for Cl-PAHs and Br-PAHs, respectively. This validated method was then applied to analyze X-PAHs in indoor dusts from a typical e-waste dismantling workshop, and the concentrations of Σ₁₈Br-PAHs (8.80-399 ng/g dw) were higher than Σ₁₆Cl-PAHs (7.91-137 ng/g dw). The toxicity equivalency quantities (TEQs) of Cl-PAHs at e-waste dismantling workshop and Br-PAHs at raw materials crushing workshop showed the highest values of 176 and 453 pg·TEQ/g, respectively. Cl-PAHs and Br-PAHs posed a potential health risk to workers through dust ingestion in workshops. Further attention should be payed to the formation mechanism of X-PAHs and the health risk.

New classes of organic pollutants in the remote continental environment - Chlorinated and brominated polycyclic aromatic hydrocarbons on the Tibetan Plateau

Halogenated polycyclic aromatic hydrocarbons are carcinogenic and ubiquitous environmental organic pollutants. The abundance and sources of these compounds have not been studied in remote environments. We collected and analyzed air, soil, lichen, and moss samples from the Tibetan Plateau. Concentrations of chlorinated polycyclic aromatic hydrocarbons were 0.78-4.16 pg/m³ in air, 3.11-297 pg/g in soil, 260-741 pg/g in lichens, and 338-934 pg/g in mosses. Concentrations of brominated polycyclic aromatic hydrocarbons were 0.15-0.59 pg/m³ in air, 0.61-72.3 pg/g in soil, 33.5-64.9 pg/g in lichens, and 20.5-72.5 pg/g in mosses. The dominant congeners were 9- and 2-chlorophenanthrene, 1-chloropyrene, 3-chlorofluoranthene, and 1-bromopyrene. We found correlations between congener concentrations in lichens and in air, and lichens effectively predicted near-ground atmospheric concentrations of the pollutants. The enrichment of photochemically stable compounds in high-altitude environments is influenced by their physicochemical properties. Principal component analysis with multivariate linear regression of chlorinated polycyclic aromatic hydrocarbons measured in lichens provided an assessment of the relative source contributions, and suggested that in Medog County of Tibetan Plateau, 48% was likely from long-range combustion sources, 26% was from local burning sources, and 26% was from photochemical formation.

Passive air sampling of halogenated polycyclic aromatic hydrocarbons in the largest industrial city in Korea: Spatial distributions and source identification

Some halogenated polycyclic aromatic hydrocarbons (Halo-PAHs) are known to be more toxic than their corresponding parent PAHs, but studies on Halo-PAHs have been somewhat limited. In this study, passive air samplers were used to monitor Halo-PAH and PAH contamination at 20 sampling sites in Ulsan, one of the largest industrial cities in South Korea. The mean concentrations of Σ₂₄ ClPAHs, Σ₁₁ BrPAHs, and Σ₁₃ PAHs were 207 pg/m³, 84 pg/m³, and 26 ng/m³, respectively. Industrial areas displayed higher concentrations of both Halo-PAHs and PAHs than urban and rural areas. Strong correlations between energetically unfavorable Halo-PAHs and their corresponding parent PAHs suggest that the main formation mechanism of Halo-PAHs is not direct halogenation of PAHs. Low molecular weight Halo-PAHs with one halogen atom and their parent PAHs were dominant. The profiles of ClPAHs and BrPAHs in petrochemical, automobile, shipbuilding, and non-ferrous industrial complexes were distinguished. The toxicity equivalency quantities (TEQs) of ClPAHs, BrPAHs, and PAHs at the industrial sites also showed the highest values of 4.2, 0.5, and 18.3 pg-TEQ/m³, respectively, reflecting the high toxicity of Halo-PAHs. To the best of our knowledge, this is the first study reporting atmospheric levels of both ClPAHs and BrPAHs using passive air samplers.

Mesoporous Ce-doped ZnO hollow microspheres for oxidation of 1,2-dichlorobenzene

ZnCe5 microspheres exhibited excellent activity in o-DCB oxidation due to the enhanced reducibility and high concentration of surface active oxygen.

Quantification of Cl-PAHs and their parent compounds in fish by improved ASE method and stable isotope dilution GC-MS

This study aimed at developing a simple and accurate method for determination of emerging chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) in fish by stable isotope dilution gas chromatography tandem mass spectrometry. Fish samples were extracted by improved accelerated solvent extraction (ASE) method. Matrix effects were observed, and matrix-matched calibration was verified with good intra-day and inter day precisions (lower than 16.1% and 15.1% respectively). Method detection limits were 0.10-5.62 ng g^-1 (dry weight) with satisfactory linearity, and recoveries ranged from 50% to 150%, with relative standard deviation values less than 18.5% at different concentration levels. This improved ASE method was proved to be suitable for analyzing Cl-PAHs in fish samples, with good analytical selectivity, linearity, recovery and precision. Furthermore, the composition analysis revealed that chlorinated compounds of phenanthrene, pyrene and acenaphthene were dominated in Cl-PAHs contaminants. The correlationship between the pollution of Cl-PAHs and their corresponding parent structures in fish samples was also analyzed in detail.

Simultaneous determination of forty-two parent and halogenated polycyclic aromatic hydrocarbons using solid-phase extraction combined with gas chromatography-mass spectrometry in drinking water

The coexistence of parent polycyclic aromatic hydrocarbons (PPAHs) and halogenated PAHs (HPAHs) in drinking water has generated much concern recently. However, a method to simultaneously determine these compounds has not been developed. In this study, a method using solid-phase extraction combined with gas chromatography-mass spectrometry for determination of PPAHs and HPAHs in drinking water was established. Forty-two target compounds including 16 PPAHs and 26 HPAHs (16 chlorinated PAHs (Cl-HPAHs) and 10 brominated PAHs (Br-PAHs)) were selected to evaluate the performance. Our results indicate enriching compounds with a LC18 cartridge and eluting with dichloromethane is optimal with recovery of 74.88-119.4%. Method detection limits ranged from 0.34 to 3.37 ng L^-1 when only using 1 L samples. The method accomplished the analysis of trace PPAHs and HPAHs. We found the coexistence of PPAHs and HPAHs including 12 PPAHs, 2 Cl-PAHs and 3 Br-PAHs in tap water samples. Maximum total concentration of PPAHs and HPAHs reached 33.69 ng L^-1 and 3.04 ng L^-1, respectively. Trace Br-PAHs were first detected in drinking water. 6-bromobenzene[a]pyrene was dominated among the HPAHs with a concentration from 2.30 to 2.69 ng L^-1. The simultaneous occurrence of PPAHs and HPAHs in drinking water should receive more attention, and their formation mechanism should be further explored.

Simultaneous determination of polycyclic aromatic hydrocarbons and their chlorinated derivatives in grilled foods

Polycyclic aromatic hydrocarbons (PAHs) are unintentionally generated in foods that are cooked, and dietary ingestion of these PAHs is regarded as the dominant route of exposure to PAHs. Some chlorinated PAHs (ClPAHs) are more toxic than their corresponding parent PAHs and can also be generated in food during cooking. Knowledge of the concentrations of ClPAHs in cooked foods has been limited by the lack of an adequate analytical method for measuring ClPAH concentrations in cooked foods. In this study, we developed an analytical method for simultaneous determination of PAHs and ClPAHs in lipid-rich foods. The combination of a potassium hydroxide silica gel column and an activated carbon cartridge enabled us to simultaneously measure PAH and ClPAH concentrations in raw and grilled fish and meats. Twelve kinds of PAHs (e.g., fluorene [Fle], phenanthrene [Phe], fluoranthene [Flu], and pyrene [Pyr]) were detected in grilled foods. The concentrations ranged from below the limit of quantitation (<LOQ) to 310 ng g^-1. We also detected 9-monochlorinated Phe (9-ClPhe), 3-monochlorinated Flu (3-ClFlu), 8-monochlorinated Flu (8-ClFlu), and 1-monochlorinated Pyr (1-ClPyr); those concentrations ranged from <LOQ to 0.16 ng g^-1. The total concentrations of PAHs were significantly lower in gas-grilled meats than in charcoal-grilled meats. In contrast, the concentrations of ClPAHs were significantly higher in gas-grilled meats than in the charcoal-grilled meats. This pattern could be attributed to the difference of reaction temperatures needed to generate them. Toxic equivalent (TEQ) concentrations, which were calculated based on toxicities relative to benzo[a]pyrene (BaP), were much higher in the grilled foods (0.12-12 ng-BaP_eq g^-1) for PAHs than for ClPAHs (<LOQ to 0.026 ng-BaP_eq g^-1).

Environmental contamination following the Grenfell Tower fire

The Grenfell Tower fire in central London, started within a flat, engulfed the whole 24 storey building in flames, killed 72 people and spread toxic effluent via the plume and particulate deposits. Soil samples from 6 locations up to 1,2 km from the Tower, together with semi-burnt fire debris and char samples, were collected 1 and 6 months after the fire. Additionally, dust samples and condensates were collected from a flat 160 m away from the Tower after 17 months. Samples were analysed for common potentially toxic components of fire effluents and synthetic vitreous fibres. Samples collected within 140 m of the Tower showed, amongst other toxicants, polychlorinated dibenzo-p-dioxin concentrations 60 times greater than UK urban reference soil levels; benzene levels were 40 times greater; levels of 6 key polycyclic aromatic hydrocarbons (PAHs) were approximately 160 times greater. PAHs levels are approximately 20 times greater than those reported from nearby Hyde Park before the fire. To explain the presence of these pyrogenic contaminants char and partially burnt debris were also collected and analysed. Benzene, PAHs, isocyanates and phosphorus flame retardants were found. Hydrogen cyanide and synthetic vitreous fibres were present in both soil and debris. Particulate and pyrogenic contamination in the immediate vicinity is clearly evident, and may have leached out of fire debris, char and dust. Further analysis of the area around the Tower is necessary to understand potential health risks.

Levels and fingerprints of chlorinated aromatic hydrocarbons in fly ashes from the typical industrial thermal processes: Implication for the co-formation mechanism

Municipal solid waste incineration (MSWI) and iron and steel making plants are two of important sources of chlorinated aromatic hydrocarbons (CAHs). In this study, the typical CAHs including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) in fly ash samples collected from MSWI, iron ore sintering (IOS) and steel smelting (SS) plants were simultaneously identified and quantified. The total concentrations of quantified CAHs in different fly ashes showed a large variation (5.88-4255 ng/g). Cl-PAHs were found to be predominant CAH species in most of fly ash samples, and the concentrations of mono-chlorinated PAHs in all fly ashes were obviously higher than those of di-chlorinated PAHs. The fingerprints of CAHs in MSWI fly ashes were mainly characterized by the high content of PCDDs, especially the hexa-CDD homologue. However, in IOS and SS fly ashes, tetra- to hexa-CDF homologues showed the higher abundance, and tetra-to octa-CDFs predominated over tetra- to octa-CDDs by factors of 3-26. The strong concentration correlations were observed between tetra- to octa-CDF homologues, middle-chlorinated PCN and PCB homologues, between tetra- to octa-CDD homologues, between low-chlorinated PCB and PCN homologues, between di-chlorinated PAH homologues, and between deca-CB and highly chlorinated PCN homologues. These results implied that the main formation mechanism of CAHs might be significantly varied with the change of chlorination degree and aromatic ring structure.