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

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

Comprehensive Evaluation of Dietary Exposure and Health Risk of Polychlorinated Naphthalenes.

Intake from food is considered an important route of human exposure to polychlorinated naphthalenes. To our knowledge, several studies have quantified dietary exposure but only in European countries and measuring only a few of the 75 congeners. In addition, the influence of source diversity on human exposure has seldom been assessed. We analyzed 192 composite food samples composed of 17,280 subsamples from 24 provinces in China to measure the concentrations of polychlorinated naphthalenes and estimate their daily intake and potential health risks on a national scale. The estimated cancer risk was in the range of 6.8 × 10-8 to 4.6 × 10-7. We compared our findings for 75 congeners with reports in the literature that quantified only 12 congeners. We estimate that these 12 congeners contribute only approximately 4% to the total mass daily intake of polychlorinated naphthalenes and 70% to the total toxic equivalent quantity, indicating underestimation of dietary exposure. The contributions of combustion-associated congeners to the total concentrations of polychlorinated naphthalenes were in the range of 31-52%, suggesting that the ongoing unintentional release of these compounds from industrial thermal processes is an important factor in polychlorinated naphthalene contamination and human exposure in China.

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.

Characterizing the emissions of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) from electric arc furnaces during steel-making.

The amount of steel produced using electric arc furnaces (EAFs) has been increasing in recent years. In this study, stack gases from EAFs in steelmaking plants were analyzed to determine if they are also dominant sources of polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/F) emissions in China. Isotope dilution high-resolution gas chromatography high-resolution mass spectrometry for qualitative and quantitative analysis of PBDD/F congeners revealed that the mean PBDD/F mass concentrations were 271.1-9467.8 pg Nm-3 for the preheating stages (PS) of three EAF plants and that the corresponding toxic equivalents (TEQs) were 10.8-971.2 pg TEQ Nm-3. The PBDD/F mass concentration from the smelting stage (SS) at plant E3 was 261.9 pg Nm-3 (4.5 pg TEQ Nm-3). The PBDD/F emission factors (EF) during the preheating stage for the three plants were 0.0356-1.51 µg TEQ t-1, and the EF was 0.0359 µg TEQ t-1 during the E3 smelting stage. PBDD/Fs were found to contribute 2.39-67.85% to the total mass and 2.84-57.68% to the total dioxin TEQ. These wide fluctuations were caused by differences in the composition of feeding materials and the working temperature of bag filters. Overall, the results indicate that PBDD/F emissions from EAF steelmaking should receive increased attention. The PBDD/F congener patterns among the three EAF plants were variable, possibly because of differences in raw materials. The results presented herein will facilitate assessment of the contribution of EAFs to total PBDD/F emissions in China and investigations of PBDD/F emissions at different stages of steelmaking processes using EAFs.

Polychlorinated Biphenyl Emissions from Steelmaking Electric Arc Furnaces.

Electric arc furnaces (EAFs) in steelmaking plants are a major source of dioxins. Preheating of steelmaking raw materials is widely used in EAFs to reduce energy consumption. Few studies have investigated emissions of dioxin-like polychlorinated biphenyls (PCBs) from EAFs, and the PCB emission levels and characteristics during preheating are unknown. In this study, PCB concentrations and distributions in stack gases emitted during EAF preheating were determined. The average dioxin-like PCB concentrations in stack gases emitted during preheating of three EAFs were 1236.1, 81,664.4, and 669.8 pg/Nm3, respectively. These values were greatly influenced by the composition of the steelmaking raw materials. The PCB profiles in all samples were dominated by less-chlorinated homologs. PCB emission factor for preheating in the EAFs is 0.58 µg WHO-TEQ/ton averagely, indicating significant emissions of PCBs from preheating process. The data will be useful for developing approaches for preventing and controlling PCB emissions from EAFs.

Rare earth elements unintentionally released from global industrial activities.

Exposure to rare earth elements (REY) in the environment can lead to adverse effects on human health. Industrial activities unintentionally produce fly ash, and a small fraction of fly ash that remains uncaptured by air pollution control devices can enter the atmosphere and contribute as a primary source of airborne fine particle matter (PM). The occurrence of REY in industrial sourced fine PM affects the environment and human health. There is relatively minimal information regarding the human health hazards and biological effects of REY in fine PM produced during industrial activities, especially for non-occupational people. In addition, REY are powerful source-specific tracers for airborne PM from industries. Therefore, relevant research on REY in fine PM from industrial processes not only contributes to understanding and preventing environmental pollution but can also provide basic data for reducing human exposure. This paper provides an overview of the research status and latest advances in various industrial processes, especially their distribution characteristics, influencing factors, tracer application, and biological effects of REY in fine PM from coal-fired power plants. We also suggest future research directions in light of existing problems.

Atmospheric emissions of fine particle matter bound rare earth elements from industry.

Unintentional releases of rare earth elements (REEs), emerging environmental pollutants, from global industries contribute to atmospheric pollution. However, a gap remains regarding the recognition of REYs in industrial fine particulate matter (PM) as a primary source of atmospheric PM. Here, we identified the characteristic of REEs in PM from 114 large-scale industries covering 13 important sectors. Based on the derived emission factors, 13 industrial sources in China emit 136,914 kg of REEs annually, with cement, coal power and coking responsible for 105,226, 12,635, and 11,940 kg/year, respectively. Source-specific elemental profiles were achieved and can be used to allocate the sources of REEs in atmosphere. The average daily intake of REEs from industrial fine PM inhalation was 11.72 ng/(kg·day) for children and 7.41 ng/(kg·day) for adults, pivotal data for assessing health risks. This study is important for sustainable industrial development and human wellness.

Diagnosis of cervical lymphoma using a YOLO-v7-based model with transfer learning.

To investigate the ability of an auxiliary diagnostic model based on the YOLO-v7-based model in the classification of cervical lymphadenopathy images and compare its performance against qualitative visual evaluation by experienced radiologists. Three types of lymph nodes were sampled randomly but not uniformly. The dataset was randomly divided into for training, validation, and testing. The model was constructed with PyTorch. It was trained and weighting parameters were tuned on the validation set. Diagnostic performance was compared with that of the radiologists on the testing set. The mAP of the model was 96.4% at the 50% intersection-over-union threshold. The accuracy values of it were 0.962 for benign lymph nodes, 0.982 for lymphomas, and 0.960 for metastatic lymph nodes. The precision values of it were 0.928 for benign lymph nodes, 0.975 for lymphomas, and 0.927 for metastatic lymph nodes. The accuracy values of radiologists were 0.659 for benign lymph nodes, 0.836 for lymphomas, and 0.580 for metastatic lymph nodes. The precision values of radiologists were 0.478 for benign lymph nodes, 0.329 for lymphomas, and 0.596 for metastatic lymph nodes. The model effectively classifies lymphadenopathies from ultrasound images and outperforms qualitative visual evaluation by experienced radiologists in differential diagnosis.

Development, Validation, and Comparison of 2 Ultrasound Feature-Guided Machine Learning Models to Distinguish Cervical Lymphadenopathy.

ABSTRACT: The objective of this study is to develop and validate the performance of 2 ultrasound (US) feature-guided machine learning models in distinguishing cervical lymphadenopathy. We enrolled 705 patients whose US characteristics of lymph nodes were collected at our hospital. B-mode US and color Doppler US features of cervical lymph nodes in both cohorts were analyzed by 2 radiologists. The decision tree and back propagation (BP) neural network were developed by combining clinical data (age, sex, and history of tumor) and US features. The performance of the 2 models was evaluated by calculating the area under the receiver operating characteristics curve (AUC), accuracy value, precision value, recall value, and balanced F score (F1 score). The AUC of the decision tree and BP model in the modeling cohort were 0.796 (0.757, 0.835) and 0.854 (0.756, 0.952), respectively. The AUC, accuracy value, precision value, recall value, and F1 score of the decision tree in the validation cohort were all higher than those of the BP model: 0.817 (0.786, 0.848) vs 0.674 (0.601, 0.747), 0.774 (0.737, 0.811) vs 0.702 (0.629, 0.775), 0.786 (0.739, 0.833) vs 0.644 (0.568, 0.720), 0.733 (0.694, 0.772) vs 0.630 (0.542, 0.718), and 0.750 (0.705, 0.795) vs 0.627 (0.541, 0.713), respectively. The US feature-guided decision tree model was more efficient in the diagnosis of cervical lymphadenopathy than the BP model.

Atmospheric emissions of particulate matter-bound heavy metals from industrial sources.

Although industrial activities are significant contributors to atmospheric releases of particulate matter (PM) and associated toxic substances that lead to adverse human health effects, a knowledge gap exists concerning the human health risk resulting from such activities owing to lack of evaluation of industrial emissions. Here, we comprehensively characterized and quantified PM from 118 full-scale industrial plants. The dominant (97.9 %) PM showed diameters of <2.5 µm; 79.0 % had diameters below 1 µm. Annual atmospheric releases of Fe and heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn) contained in fine PM from these global industrial activities are estimated to be 51,161 t and 69,591 t, respectively. Emissions of heavy metals from these industries cause increased cancer risk, estimated to range from 1461 % to 50,752 %. Five crystalline compounds (ZnO, PbSO4, Mn3O4, Fe3O4, Fe2O3) that can indicate specific industrial sources are identified. Global annual emissions of these toxic compounds in fine PM from the industrial sources are estimated to be 78,635 t. The Global South displayed higher emissions than the Global North. These results are significant for recognizing regional health risks of industrial emissions.

Atmospheric emissions of hexachlorobutadiene in fine particulate matter from industrial sources.

Hexachlorobutadiene (HCBD) is a concerning chemical that is included in the United States Toxic Substances Control Act, and the Stockholm Convention. Knowledge of the sources of HCBD is insufficient and is pivotal for accurate inventory and implementing global action. In this study, unintentional HCBD release and source emission factors of 121 full-scale industrial plants from 12 industries are investigated. Secondary copper smelting, electric arc furnace steelmaking, and hazardous waste incineration show potential for large emission reductions, which are found of high HCBD emission concentrations of > 20 ng/g in fine particulate matter in this study. The highest HCBD emission concentration is observed for the secondary copper smelting industry (average: 1380 ng/g). Source emission factors of HCBD for the 12 industries range from 0.008 kg/t for coal fire power plants to 0.680 kg/t for secondary lead smelting, from which an estimation of approximately 8452.8 g HCBD emissions annually worldwide achieved. The carcinogenic risks caused by HCBD emissions from countries and regions with intensive 12 industrial sources are 1.0-80 times higher than that without these industries. These results will be useful for formulating effective strategies of HCBD control.

Occurrences and spatial distributions of dioxin-like polychlorinated biphenyls in chlorobenzene and chloroethylene manufacturing processes in China.

As a group of pollutants listed in the Stockholm Convention, polychlorinated biphenyls (PCB) should be eliminated and their releases should be controlled. For this purpose, a complete PCB emission inventory is urgently required. Current unintentional releases of PCB were dominantly focused on waste incineration and non-ferrous metal production industries. The formation of PCB in chlorinated chemical manufacturing processes is poorly understood. In this study, occurrences and inventory of dioxin-like PCB (dl-PCB) in three typical chemical manufacturing processes, including chlorobenzene and chloroethylene production processes, were investigated. The bottom residues, which were high boiling point by-products after rectification tower, contained higher concentration of PCB than other stage samples in monochlorobenzene production and trichloroethylene production processes. The PCB concentrations were as high as 1.58 ng/mL and 152.87 ng/mL, respectively, which should be further concerned. The toxic equivalent quantities (TEQ) of dl-PCB in monochlorobenzene, trichloroethylene, and tetrachloroethylene products were 0.25 µg TEQ/t, 1.14 µg TEQ/t, and 5.23 µg TEQ/t, respectively. The mass concentration and TEQ of dl-PCB determined in this research can be used for the further development of dl-PCB emission inventory from these chemical manufacturing industries. In addition, temporal and spatial trends of PCB releases from typical chemical manufacturing processes from 1952 to 2018 in China were clarified. The releases increased rapidly in the latest two decades and presented an expansion tendency from the southeast coastal areas to northern and central areas. The continuing upward trend for the output and the high dl-PCB TEQ of chloroethylene indicated significant releases of PCB from chemical manufacturing processes and should receive more attention.

Industrial source identification of polyhalogenated carbazoles and preliminary assessment of their global emissions.

Polyhalogenated carbazoles (PHCZs) are emerging global pollutants found in environmental matrices, e.g., 3000 tonnes of PHCZs have been detected in the sediments of the Great Lakes. Recognition of PHCZ emissions from ongoing industrial activities worldwide is still lacking. Here, we identify and quantify PHCZ emissions from 13 large-scale industries, 12 of which previously have no data. Congener profiles of PHCZs from investigated industrial sources are clarified, which enables apportioning of PHCZ sources. Annual PHCZ emissions from major industries are estimated on the basis of derived emission factors and then mapped globally. Coke production is a prime PHCZ emitter of 9229 g/yr, followed by iron ore sintering with a PHCZ emission of 3237 g/yr. China, Australia, Japan, India, USA, and Russia are found to be significant emitters through these industrial activities. PHCZ pollution is potentially a global human health and environmental issue.

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 characteristics and formations of polybrominated dibenzo-p-dioxins and dibenzofurans.

Polybrominated dibenzo-p-dioxins and furans (PBDD/Fs) are emerging persistent organic pollutants (POPs) that have similar or higher toxicities than the notorious dioxins. Toxicities, formation mechanisms, and environmental fates of PBDD/Fs are lacking because accurate quantification, especially of higher brominated congeners, is challenging. PBDD/F analysis is difficult because of photolysis and thermal degradation and interference from polybrominated diphenyl ethers. Here, literatures on PBDD/F analysis and environmental occurrences are reviewed to improve our understanding of PBDD/F environmental pollution and human exposure levels. Although PBDD/Fs behave similarly to dioxins, different congener profiles between PBDD/Fs and dioxins in the environment indicates their different sources and formation mechanisms. Herein, potential sources and formation mechanisms of PBDD/Fs were critically discussed, and current knowledge gaps and future directions for PBDD/F research are highlighted. An understanding of PBDD/F formation pathways will allow for development of synergistic control strategies for PBDD/Fs, dioxins, and other dioxin-like POPs.

Concentrations and profiles of persistent organic pollutants unintentionally produced by secondary nonferrous metal smelters: Updated emission factors and diagnostic ratios for identifying sources.

Secondary nonferrous metal smelters are important sources of unintentionally produced persistent organic pollutants (UPOPs) including polychlorinated biphenyls (PCBs), polychlorinated naphthalenes, pentachlorobenzene, and hexachlorobenzene. Quantifying UPOP emissions by the main sources is an important step when evaluating UPOP emissions and establishing an inventory. In this study, field investigations were performed to allow UPOP emissions and distributions in stack gases emitted by secondary nonferrous metal smelters to be compared. A total of 25 stack gas samples were collected from secondary copper smelters (SCus), secondary zinc smelters, and secondary lead smelters in China. The mean toxic equivalent concentrations (TEQs) and mass concentrations of most of the UPOPs were highest in the secondary zinc smelter stack gas samples, next highest in the SCu stack gas samples, and lowest in the secondary lead smelter stack gas samples. The mean dioxin-like PCB and polychlorinated naphthalene TEQs were ∼8.9 and ∼6.6 times higher in stack gases from a SCu equipped with an oxygen-enriched smelting furnace than in stack gases from a SCu with a converter furnace. The mean PCB-118 to PCB-123 ratios and CN-10 to CN-35 ratios varied strongly and could be used as diagnostic ratios for apportioning the sources of UPOPs in the environment. Emission factors for dioxin-like PCBs, polychlorinated naphthalenes, pentachlorobenzene, and hexachlorobenzene in stack gases from secondary nonferrous metal smelters were derived and updated. The results improve our understanding of UPOP emission and provide data for establishing UPOP emission inventories for secondary nonferrous metal smelters.