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Background: Bladder cancer has been linked to several occupations that involve the use of solvents, including those used in the dry-cleaning industry., Objectives: We evaluated exposure to solvents and risk of bladder cancer in 1182 incident cases and 1408 controls from a population-based study., Methods: Exposure to solvents was quantitatively assessed using a job-exposure matrix (CANJEM). Exposure to benzene, toluene and xylene often co-occur. Therefore, we created two additional sets of metrics for combined benzene, toluene and xylene (BTX) exposure: (1) CANJEM-based BTX metrics and (2) hybrid BTX metrics, using an approach that integrates the CANJEM-based BTX metrics together with lifetime occupational histories and exposure-oriented modules that captured within-job, respondent-specific details about tasks and chemicals. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using logistic regression., Results: Bladder cancer risks were increased among those ever exposed to benzene (OR = 1.63, 95% CI: 1.14-2.32), toluene (OR = 1.60, 95% CI: 1.06-2.43), and xylene (OR = 1.67, 95% CI: 1.13-2.48) individually. We further observed a statistically significant exposure-response relationship for cumulative BTX exposure, with a stronger association using the hybrid BTX metrics (OR Q1vsUnexposed  = 1.26, 95% CI: 0.83-1.90; OR Q2vsUnexposed  = 1.52, 95% CI: 1.00-2.31; OR Q3vsUnexposed  = 1.88, 95% CI: 1.24-2.85; and OR Q4vsUnexposed  = 2.23, 95% CI: 1.35-3.69) (p-trend=0.001) than using CANJEM-based metrics (p-trend=0.02)., Impact: There is limited evidence about the role of exposure to specific organic solvents, alone or in combination on the risk of developing bladder cancer. In this study, workers with increasing exposure to benzene, toluene, and xylene as a group (BTX) had a statistically significant exposure-response relationship with bladder cancer. Future evaluation of the carcinogenicity of BTX and other organic solvents, particularly concurrent exposure, on bladder cancer development is needed., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

With the development of the chemical industry, benzene, toluene, ethylbenzene, and xylene (BTEX) have gradually become the major indoor air pollutants. Various gas treatment techniques are widely used to prevent the physical and mental health hazards of BTEX in semi-enclosed spaces. Chlorine dioxide (ClO 2 ) is an alternative to chlorine as a secondary disinfectant with a strong oxidation ability, a wide range of action, and no carcinogenic effects. In addition, ClO 2 has a unique permeability which allows it to eliminate volatile contaminants from the source. However, little attention has been paid to the removal of BTEX by ClO 2 , due to the difficulty of removing BTEX in semi-enclosed areas and the lack of testing methods for the reaction intermediates. Therefore, this study explored the performance of ClO 2 advanced oxidation technology on both liquid and gaseous benzene, toluene, o-xylene, and m-xylene. The results showed that ClO 2 was efficient in the removal of BTEX. The byproducts were detected by gas chromatography-mass spectrometry (GC-MS) and the reaction mechanism was speculated using the ab initio molecular orbital calculations method. The results demonstrated that ClO 2 could remove the BTEX from the water and the air without causing secondary pollution.

Objective: This study was designed to conduct a retrospective and systematic occupational health risk assessment (OHRA) of enterprises that used benzene, toluene, and xylene (BTX) in Shanghai, China., Methods: All data for the study were obtained from 1,705 occupational health examination and evaluation reports from 2013 to 2017, and a semiquantitative model following Chinese OHRA guidelines (GBZ/T 298-2017) was applied for the assessment., Results: The selected enterprises using BTX were mainly involved in manufacturing of products. Using the exposure level method, health risk levels associated with exposure to BTX were classified as medium, negligible, or low. However, the risk levels associated with benzene and toluene were significantly different according to job types, with gluers and inkers exhibiting greater health risks. For the same job type, the health risk levels assessed using the comprehensive index method were higher than those using the exposure level method., Conclusion: Our OHRA reveals that workers who are exposed to BTX still face excessive health risk. Additionally, the risk level varied depending on job categories and exposure to specific chemicals. Therefore, additional control measures recommended by OHRA guidelines are essential to reduce worker exposure levels., (Copyright © 2021 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

Objective: To study the effects of combined occupational exposure of benzene, toluene, and xylene on human metabolism at an overall level, and to screen biomarkers related to the combined occupational exposure of benzene, toluene, and xylene, and to explore the mechanism of early health effects preliminarily caused by combined occupational exposure of benzene, toluene, and xylene by identification of biomarkers and retrieval of metabolic pathways. Methods: A shoe-making company was selected as the research site. Twenty subjects for the exposed group and the control group were selected separately, and urine of the subjects was collected. The metabolic profiles of the samples were collected by liquid chromatography time-of-flight mass spectrometry, and professional metabolomics and multivariate statistical analysis software were used to establish PCA and OPLS-DA analysis models to screen potential biomarkers and identify biomarkers. Finally, based on the dynamic changes and trends of potential biomarkers between groups, the mechanism of body damage caused by benzene, toluene, and xylene was initially explored. Results: Urine metabolomics analysis showed that the metabolic profile of urine samples of the benzene, toluene, and xylene combined exposure group was different from that of the control group. 27 potential biomarkers that were closely related to the combined exposure of benzene, toluene, and xylene were screened and identified. These potential biomarkers were enriched in 16 metabolic pathways, of which 3 pathways were significantly enriched ( P <0.05) , respectively, lysine metabolism, amino sugar metabolism, and nucleotide sugar metabolism. Conclusion: The metabonomics method can well reflect the changes in the metabolome of urine samples in the occupational population after the combined exposure of benzene, toluene, and xylene, which will help us better evaluate the risk of combined exposure of benzene, toluene, and xylene and prevent and control their health risks.

Objective: To learn about the cardiovascular health effects of workers expose to benzene-toluene-xylene and noise in painting workshop of automobile manufacturing enterprises, and to provide intervention measures and strategies for the health of workers. Methods: The effects of noise exposure, benzene-toluene-xylene exposure and combined exposure on workers' blood pressure and electrocardiogram were analyzed through epidemiological investigation, workplace monitoring and occupational health examination in several automobile enterprises which had carried out occupational hazard factors monitoring and occupational health examination in our hospital from April to October 2017. Results: There were differences in age, sex, working years, smoking, drinking and physical exercise among workers in different exposure groups ( P <0.05) . The systolic blood pressure level of workers in benzene-toluene-xylene exposure group and combined exposure group was significantly different comparing with control group ( P < 0.05) , After the factors of age and working years were adjusted. The abnormity rate of electrocardiogram in workers were not statistically significant in all groups ( P >0.05) . Conclusion: The benzene-toluene-xylene exposure and noise combined with benzene-toluene-xylene exposure in painting workshop of automobile manufacturing enterprises has positive influence on the systolic blood pressure of workers. Regular physical examination and health intervention measures should be strengthened to improve health.

The assessment of benzene, toluene, ethyl-benzene, and xylene (BTEX)-contaminated soil toxicity was performed using a sulfur-oxidizing bacteria (SOB) assay. The experiments were set up using an individual pollutant in a 25-mL bottle sealed with a rubber stopper and aluminum cap since BTEX are volatile. A large headspace volume (14 mL) was kept in the reactors to provide enough oxygen for the SOB. Soil samples were spiked with BTEX compounds in the concentration range of 1-1000 mg/kg. In reactors without BTEX compounds, approximately 85% of the theoretically required oxygen was consumed. Whereas, the reactors with benzene consumed in the range of 82-64% (5-100 mg/kg), those with toluene consumed 76-53% (1-50 mg/kg), those with ethyl-benzene consumed 44-71% (5-100 mg/kg), and those with xylene consumed 64-71% (1-10 mg/kg) of the theoretically required oxygen. The effective concentrations responsible for 50% growth inhibition (EC 50 ) for benzene, toluene, ethyl-benzene, and xylene detection were 130.2, 1.2, 15.2, and 0.7 mg/kg, respectively. These results suggest that this SOB-based bioassay can detect BTEX pollutants in soils., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Benzene, toluene and xylene (BTX) are aromatic hydrocarbons with inconclusive evidence of lung carcinogenicity. The aim of this research was to assess the associations between occupational exposures to BTX agents and lung cancer., Methods: In a population-based case-control study of lung cancer, occupational histories were obtained and exposures were assessed by experts. Unconditional multivariate logistic regression was used to estimate ORs and 95% CIs, among men, between various metrics of occupational exposure to BTX and lung cancer, while adjusting for established and possible risk factors., Results: Considerable overlap was found between occupational exposure to BTX, where the majority of exposed participants were exposed to all three chemicals. Lung cancer was associated with exposure to benzene (OR=1.35; 95% CI 0.99 to 1.84), toluene (OR=1.31; 95% CI 0.99 to 1.74) and xylene (OR=1.44; 95% CI 1.03 to 2.01). While these results were adjusted for smoking and other recognised and possible lung cancer risk factors, they were not mutually adjusted among the three BTX agents., Conclusions: Our study provides suggestive evidence that occupational exposure to one or more of the BTX agents may be associated with lung cancer., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Objectives: While several monocyclic aromatic hydrocarbons are classified as definite or possible carcinogens to humans, little data exist on their role in prostate cancer (PCa). We examined occupational exposure to benzene, toluene, xylene (BTX) and styrene and PCa risk in a population-based case-control study in Montreal, Canada., Methods: Cases aged ≤75 years diagnosed with PCa in 2005-2009 (n=1920) and population controls frequency-matched on age (n=1989) provided detailed work histories. Experts evaluated the certainty, frequency and concentration of exposure to monocyclic aromatic hydrocarbons in each job lasting ≥2 years. Logistic regression estimated OR and 95% CIs for PCa risk, adjusting for potential confounders., Results: Exposures to BTX were highly intercorrelated, except for durations of exposure at substantial levels. Ever exposure to any BTX was associated with overall PCa (OR 1.27, 95% CI 1.05 to 1.53), while the OR for styrene was 1.19. However, increases in risk were largely confined to low-grade tumours, with ORs of 1.33 (95%CI 1.08 to 1.64) and 1.41 (95% CI 0.85 to 2.31) for ever exposure to any BTX and styrene, respectively, and a duration response pattern for any BTX. Risks for low-grade tumours were elevated among men exposed ≥25 years at substantial levels of benzene (OR 2.32) and styrene (OR 2.44). Some cumulative exposure categories showed increased risks but without clear trends., Conclusion: Exposure to any BTX was associated with higher risks of overall PCa. Prolonged exposures at the substantial level to benzene and styrene increased risks of low-grade tumours. These novel findings were independent from PCa screening., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2018. No commercial re-use. See rights and permissions. Published by BMJ.)

Emissions of BTEX (benzene, toluene, ethylbenzene and xylene) from the petrochemical industry are characterized by a low pollutants concentration and the absence of oxygen. Biodegradation of these pollutants using nitrate as the electron acceptor is of key interest to reuse the residual gas for inertization purposes. However, the biological mineralization of BTEX is often limited by their recalcitrant nature and the toxicity of the secondary metabolites produced. The potential of an anoxic biotrickling filter for the treatment of a model O 2 -free BTEX-laden emission at inlet individual concentrations of ~700mgm -3 was here evaluated. A UV oxidation step was also tested both in the recycling liquid and in the inlet gas emission prior to biofiltration. Removal efficiencies >90% were achieved for both toluene and ethylbenzene, corresponding to elimination capacities (ECs) of 1.4±0.2gm -3 h -1 and 1.5±0.3gm -3 h -1 , respectively, while ~45% of xylene (EC=0.6±0.1g m -3 h -1 ) was removed at a liquid recycling rate of 2mh -1 . Benzene biodegradation was however limited by the accumulation of toxic metabolites in the liquid phase. The oxidation of these intermediates in the recycling liquid by UV photolysis boosted benzene abatement, achieving an average EC of 0.5±0.2gm -3 h -1 and removals of ~40%. However, the implementation of UV oxidation as a pretreatment step in the inlet gas emission resulted in the deterioration of the BTEX biodegradation capacity of the biotrickling filter. Finally, a high bacterial diversity was observed throughout the entire experiment, the predominant phyla being Proteobacteria and Deinococcus-thermus., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Brazilian gas station workers are chronically exposed to benzene, toluene, xylene (BTX) during their working time. Describe below two cases of latin female gas station workers with benzene poisoning symptoms and miscarriage history., Case Presentation: In both cases were identified complex chromosomal rearrangements (CCR) with fluorescence in situ hybridization, applied to whole chromosome paints by chromosomes 1, 2 and 4. The lower natural killer cell (NK) cells have also been observed in cases correspondents, especially the rare type of NK (NKbright) in their peripheral blood cells., Conclusions: It is known that acquired chromosomal aberrations are positively correlated with cancer and reproductive risk. In concordance, lower NK cytotoxicity increases the risk for cancer, as well. Thus, this is the first study providing hints on a possible causative relation of lower NK cytotoxicity and increase rates of chromosomal rearrangements including CCRs.

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BackgroundA large body of cross-sectional studies have indicated a correlation between exposure to benzene series and increased rates of menstrual abnormalities in female workers, but these findings are confusing as evidence in the field of preventive medicine. ObjectiveTo provide a more rigorous scientific basis for early prevention of reproductive function impairment through systematic review of independent studies. MethodsA comprehensive search was conducted for scientific articles published between January 1987 and July 2022, encompassing databases such as PubMed, Medline, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang Data, and CQVIP. A meta-analysis was conducted on literature that met the stringent criteria for case-control studies, featuring well-defined and consistent datasets. A meticulous investigation was executed to ascertain the collective odds ratio (OR) linked to menstrual abnormalities, encompassing diverse categories such as component, dosage, cumulative exposure dosage, and age groups. The prevalence and corresponding risk fractions were estimated by calculating frequency distributions and attributing risk percentages (AR). ResultsA total of 53 papers of case-control studies were included in the meta-analysis, involving 27068 benzene series-exposed female workers and 22857 control female workers. During inhalation exposure to benzene series, benzene, toluene, and xylene all increased the risk of female menstrual abnormalities (OR=3.46, 95%CI: 2.79, 4.30, AR=29.37%). The OR value elevated with the increase of joint exposure concentration (OR=2.57-4.33), the OR value of the low cumulative exposure group was lower than that of the high cumulative exposure group (OR=2.81 vs 3.86, P < 0.01), and the OR value of the group aged 18 to 36 years old was higher than that of the group aged 18 to 45 years old (OR=5.83 vs 2.93, P < 0.01). The OR value discrepancy was apparent among the groups with single and multi-components of benzene, toluene, and xylene at different concentrations (OR=2.39-6.42, 95%CI: 1.26, 9.06). The symptom dimensions of menstrual abnormalities with a higher AR were abnormal menstrual volume (AR=47.12%), followed by abnormal menstrual cycle (AR=38.68%). The symptoms that were greatly influenced by the exposures were: irregular menstrual cycle (OR=3.33, 95%CI: 2.94, 3.79, AR=51.25%, n=1103), menorrhagia (OR=3.02, 95%CI: 2.76, 3.30, AR=46.73%, n=2262), dysmenorrhea (OR=3.22, 95%CI: 2.69, 3.84, AR=44.18%, n=3183), and prolonged menstrual duration (OR=2.20, 95%CI: 1.99, 2.43, AR=37.02%, n=1452). Conclusion Through inhalation exposure to benzene series, a higher concentration of combined benzene, toluene, and xylenes may increase the risk of menstrual abnormalities in female workers of childbearing age. The OR value of menstrual abnormalities is varied by chemical composition, exposure dose, cumulative exposure dose, and age. Volume and cycle of menstruation are affected by the exposure, and the most common symptoms are dysmenorrhea, menorrhagia, irregular cycle.

BackgroundWorkers engaged in benzene-exposed or benzene-containing solvent-exposed operations in China are predominantly subjected to a low concentration of benzene series compounds, and prolonged exposure to low concentrations of benzene, toluene, and xylene (BTX) may have implications for blood pressure. ObjectiveTo investigate the influence of low-concentration BTX exposure on the blood pressure of workers, aiming to provide a basis for enterprises to devise associated health management strategies to mitigate the occurrence of hypertension among workers exposed to low concentrations of BTX. MethodsUsing a cross-sectional design, 884 workers from a petroleum refining enterprise in Hainan who participated in an occupational health examination in 2022 were selected as the study population, and were divided into an exposure group of 649 workers and a control group of 235 workers based on their reporting of BTX exposure or not. Data on workplace BTX concentrations and health examinations of the study subjects were collected and questionnaires were administered. In addition, S-phenylmercapturic acid (S-PMA), hippuric acid (HA), and methyl hippuric acid (MHA, including the three isomers 2-MHA, 3-MHA, and 4-MHA) were measured in the urine of the workers using high-performance liquid chromatography-tandem triple quadrupole mass spectrometry to assess internal BTX burden. The effects of low-concentration BTX exposure on blood pressure were analyzed. ResultsIn 2022, the concentrations of benzene, toluene, and xylene of all monitoring points did not exceeded the national limits by either time-weighted average (TWA) or short-term exposure limit (STEL), indicating low-concentration BTX exposure. Regarding the internal burden of BTX, the concentrations of benzene metabolite S-PMA, toluene metabolite HA, and xylene metabolites 3-MHA and 4-MHA in the urine samples in the exposure group were higher than those in the control group (P < 0.05). The correlation analysis showed a positive correlation between urinary S-PMA concentration and diastolic blood pressure in the workers (r=0.265, P < 0.05). Differences in systolic and diastolic blood pressure distributions were statistically significant among workers grouped by sex, age, work years, educational levels, monthly income, body mass index (BMI), alcohol use, dietary oil, and types of residential address (P < 0.05). Significant differences in systolic blood pressure distribution were observed among workers by smoking status and levels of labor intensity (P < 0.05). Compared with the control group, the workers in the exposure group exhibited a significant increase in diastolic blood pressure (P < 0.05). The results of multiple linear regression showed that age, sex, and BMI had statistically significant effects on systolic blood pressure (P < 0.05), while age, work years, and BMI had statistically significant effects on diastolic blood pressure (P < 0.05). The systolic blood pressure of age > 35 years, male, overweight and obese workers was significantly higher than that of age ≤ 35 years, female, and underweight workers, and the diastolic blood pressure of age > 35 years, work years > 5 years, and obese workers was higher than age ≤35 years, ≤5 years of service, and underweight workers. Low-concentration BTX exposure was one of the main influencing factors for elevated diastolic blood pressure, and the exposed workers showed a 1.337 mmHg increase in diastolic blood pressure compared to the control group (P < 0.05). ConclusionLow-concentration BTX exposure, work years > 5 years, and obesity may elevate blood pressure among petroleum refininig workers. Regular blood pressure monitoring and enhanced health interventions for this occupational group are warranted.

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to evaluate the beneficiation plant environment in a more scientific and reasonable way, this paper took the workshop environment of the beneficiation plant as the research object. This paper divided the beneficiation plant into 7 evaluation units according to its functions. The evaluation indices are dust, noise, light environment, microclimate, benzene, toluene and xylene. This paper combines the G1 method and the entropy weight method to evaluate the weight of each evaluation index, the element extension model of the concentrator working environment is established by the element analysis method, and the matter element analysis method is used to establish an evaluation index system of a beneficiation plant in East China. The results show that the evaluation level of the breaking workshop and the auxiliary facilities are unqualified, the auxiliary facility is qualified, the culling workshop, culled yard and accessory building are medium, the screening workshop and grinding workshop are good. [ABSTRACT FROM AUTHOR]

Sheet-like ZSM-5 zeolites with varied b-axis thicknesses (92, 160, 264 and 407 nm, respectively) and equivalent Si/Al molar ratios (ca. 150) were prepared using urea as additive in the aluminosilicate gels, and studied with respect to their performance in benzene alkylation with methanol. The ZSM-5 samples have similar textural properties and acidic properties. Catalytic tests show that these catalysts exhibit comparable benzene conversions of ca. 64% at 400 °C and WHSV of 2 h−1. The correlation between the selectivity of toluene and xylene and the ZSM-5 crystal size in the b-axis can be established. As the b axis length is decreased from 407 to 92 nm, the selectivity to toluene and xylene increases obviously from 80.3 to 87.4%, which is attributed to enhanced diffusion property of ZSM-5 zeolite. This finding provides an alternative strategy to improve the selectivity of toluene and xylene in the alkylation of benzene with methanol over ZSM-5-based catalysts. [ABSTRACT FROM AUTHOR]

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one‐pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non‐natural three‐enzyme cascade for one‐pot conversion of biobased l‐phenylalanine into ethylbenzene. The key rate‐limiting photodecarboxylase was subjected to structure‐guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3‐fold higher productivity. With this improved photodecarboxylase, an optimized two‐cell sequential process was developed to convert l‐phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one‐pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals. [ABSTRACT FROM AUTHOR]

This work reports the development of an electrochemical sensor for the simultaneous determination of benzene, toluene and xylene (BTX). The sensor was prepared by coating the glassy carbon electrode (GCE) with reduced graphene oxide (RGO) film, decorated with gold nanoparticles (AuNP), by electrodeposition. Surface modification with AuNP/RGO‐GCE favored the electron transfer process and increased the active area, providing greater sensitivity for the sensor. The AuNP/RGO‐GCE sensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). Quantitative analyses of BTX were carried out using the differential pulse voltammetry (DPV) technique, after optimization of the parameters that influence the sensor performance. The sensor showed a linear response in the 30–240 μM concentration range, with a detection limit range of 1.8–2.2 μM, 2.2–2.7 μM, and 2.0–2.6 μM, and quantification limit range of 6.2–7.3 μM, 7.2–8.9 μM, and 6.6–8.8 μM, respectively for B, T and X. In addition to the satisfactory repeatability and stability, in the determination of BTX, the method still showed good selectivity even in the presence of molecules with similar chemical structure, such as: catechol, p‐benzoquinone, resorcinol, ethanol, pyrene and in the presence of K+, Mg2+ and Pb2+ ions. The device was successfully applied for the determination of the analytes (BTX) in water samples from fuel station separator boxes, where recovery rates close to 100 % (97.8 % to 103.1 %) were obtained. The results obtained suggest that the AuNP/RGO‐GCE sensor has strong potential for detecting BTX in wastewater discharge from industrial processes. [ABSTRACT FROM AUTHOR]

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) such as benzene, toluene, and xylene are toxic air pollutants which are released into the atmosphere by various human activities such as gasoline production and use, chemical manufacturing and incineration of certain waste. These pollutants are also harmful to the environment, causing harm to plants, aquatic life, and soil quality. Therefore, it is important to implement measures to reduce emissions from these substances. The purpose of this paper is to evaluate the air pollutants caused by benzene, toluene, and xylene at Kazakhstan Petrochemical Industries Inc. LLP in 2021–2022. In order to calculate the sample size for this crosssectional study, the preliminary evaluation findings from a related study that measured the concentration of hydrocarbons in petrochemical facilities were employed. 281 samples were gathered between the winter and summer of 2022. The national institute for occupational safety and health (NIOSH) methods of 1501 was applied to conduct the sampling and analysis of pollutants. The air was sampled using a charcoal tube sampler that was attached to a pump. The chemicals were then extracted using the solvent carbon disulfide (CS2 ), and samples were then analyzed using a capillary-equipped gas chromatography-mass spectrometer. The collected data were analyzed by SPSS software version 23.0. The findings demonstrated that benzene concentrations in the sampling areas throughout the winter and summer were higher than the recommended value advised by the American conference of governmental industrial hygienists (ACGIH). [ABSTRACT FROM AUTHOR]

Styrene, benzene, toluene, ethylbenzene, and xylenes (SBTEX) are established neurotoxicants. SBTEX contains hazardous air pollutants (HAPs) that are released from the petrochemical industry, combustion process, transport emission, and solvent usage sources. Although several SBTEX toxic assessment studies have been conducted, they have mainly relied on ambient measurements to estimate exposure and limit their scope to specific locations and observational periods. To overcome these spatiotemporal limitations, an air quality modeling system over the US Gulf region was created, predicting the spatially and temporally enhanced SBTEX modeling concentrations from May to September 2012. Due to the incompleteness of SBTEX in the official US Environmental Protection Agency (EPA) National Emission Inventory (NEI), the Hazardous Air Pollutions Imputation (HAPI) program was used to identify and estimate the missing HAP emissions. The improved emission data were processed to generate the chemically speciated hourly gridded emission inputs for the Comprehensive Air Quality Model with Extensions (CAMx) chemical transport model to simulate the SBTEX concentrations over the Gulf modeling region. SBTEX pollutants were modeled using the Reactive Tracer feature in CAMx that accounts for their chemical and physical processes in the atmosphere. The data show that the major SBTEX emissions in this region are contributed by mobile emissions (45 %), wildfire (30 %), and industry (26 %). Most SBTEX emissions are emitted during daytime hours (local time 14:00–17:00), and the emission rate in the model domain is about 20–40 t h -1 , which is about 4 times higher than that in the nighttime (local time 24:00–04:00, about 4–10 t h -1). High concentrations of SBTEX (above 1 ppb) occurred near the cities close to the I-10 interstate highway (Houston, Beaumont, Lake Charles, Lafayette, Baton Rouge, New Orleans, and Mobile) and other metropolitan cities (Shreveport and Dallas). High styrene concentrations were co-located with industrial sources, which contribute the most to the styrene emissions. The HAPI program successfully estimated missing emissions of styrene from the chemical industry. The change increased total styrene emissions by 22 %, resulting in maximum ambient concentrations increasing from 0.035 to 1.75 ppb across the model domain. The predicted SBTEX concentrations with imputed emissions present good agreement with observational data, with a correlation coefficient (R) of 0.75 (0.46 to 0.77 for individual SBTEX species) and a normalized mean bias (NMB) of -5.6 % (-24.9 % to 32.1 % for the individual SBTEX species), suggesting their value for supporting any SBTEX-related human health studies in the Gulf region. The SBTEX data were published at Zenodo (10.5281/zenodo.7967541) (Wang et al., 2023), and the HAPI tool was also published at Zenodo (10.5281/zenodo.7987106) (Wang and Baek, 2023). [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (AlF) distributions, but otherwise quite similar textural and acidic properties, have been prepared by employing tetrapropylammonium hydroxide (TPAOH) and n-butylamine (NBA) as organic structure-directing agents (OSDAs). Systematical investigations demonstrate that AlF is preferentially located at the intersections in MFI topology when TPAOH is adopted. In contrast, less AlF is positioned therein as NBA is utilized. Density functional theory (DFT) calculations reveal that the transition-state complexes cannot be formed in the straight and sinusoidal channels due to their much smaller sizes than the dynamic diameters of transition states, whereas there are adequate spaces for the formation of transition states at the intersections. Benefitting from abundant AlF at the intersections, which provides more acid sites therein, H-ZSM-5 synthesized from TPAOH is more active relative to the counterpart obtained from NBA. At a WHSV of 4 h−1 and 400 °C, the former catalyst gives a 52.8% conversion, while the latter one affords a 45.9% conversion. Both catalysts display close total selectivity towards toluene and xylene (ca. 84%). This study provides an efficient way to regulate the distribution of acid sites, thereby enhancing the catalytic performance of H-ZSM-5 zeolite in the titled reaction. [ABSTRACT FROM AUTHOR]

Due to its excellent properties, polydimethylsiloxane (PDMS) foam has recently attracted significant academic and industrial attention. In this study, a facile and green method was developed for PDMS foam synthesis. The PDMS foam was prepared by using the gas foaming method with eco-friendly materials, namely NaHCO3 as a blowing agent and acetic acid as the catalyst. By changing the ratios of the reactants and the curing temperature, foams with varying properties were obtained. The water contact angle of the obtained PDMS foams ranged from 110° to 139°. We found that the PDMS foams can be compressed to a maximum strain of 95% and retain their original size, showing excellent mechanical properties. The synthesized PDMS foams were tested as an absorbent to remove benzene, toluene, and xylene (BTX) from the water. It exhibited good selectivity, outstanding reusability, and absorption capacity. Its capability to remove a large amount of organic solvent from the water surface suggests the great promise of PDMS foam in recovering spilled organic compounds from water, with excellent separation performance for continuous treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] Advancing the practical application of catalytic oxidation technology demands for illustrating the synchronous conversion behavior of various volatile organic compounds (VOCs) over catalysts. Here, the mutual effects of benzene, toluene and xylene (BTX) were examined for their synchronous conversion on the surface of the MnO 2 nanowire. Competitive adsorption of xylene (absorption energy (E ads): −0.889 eV) facilitated its prior conversion and impeded the oxidization of toluene and benzene over the catalyst. The turnover frequencies were 0.52 min−1 (benzene), 0.90 min−1 (toluene) and 2.42 min−1 (xylene) for mixed BTX conversion over the MnO 2. Doping MnO 2 with K+, Na+ and Ca2+ could enhance its ability to oxidize the individual VOCs but did not alter the conversion mechanism of mixed BTX over the catalyst. When reducing the competitive effects in the adsorption of BTX, the oxidation performance of catalysts would depend on their ability to oxidize toluene and benzene. K-MnO 2 showed superior properties, i.e. specific surface area, highly low-valent Mn species, high lattice oxygen content, and abundant oxygen vacancy, and then exhibited superior performance during long-term operation (90% conversion in 800 min). The present study uncovered the co-conversion mechanism of multiple VOCs and significantly leveraged the catalytic oxidization technology for VOCs removal in practical application. [ABSTRACT FROM AUTHOR]

The health risk and burden of disease induced by exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) in the outdoor air in Tehran, 2019 were assessed based on the data of five fixed stations with weekly BTEX measurements. The non-carcinogenic risk, carcinogenic risk, and disease burden from exposure to BTEX compounds were determined by hazard index (HI), incremental lifetime cancer risk (ILCR), and disability-adjusted life year (DALY), respectively. The average annual concentrations of benzene, toluene, ethylbenzene, and xylene in the outdoor air in Tehran were 6.59, 21.62, 4.68, and 20.88 μg/m3, respectively. The lowest seasonal BTEX concentrations were observed in spring and the highest ones occurred in summer. The HI values of BTEX in the outdoor air in Tehran by district ranged from 0.34 to 0.58 (less than one). The average ILCR values of benzene and ethylbenzene were 5.37 × 10-5 and 1.23 × 10-5, respectively (in the range of probable increased cancer risk). The DALYs, death, DALY rate (per 100,000 people) and death rate (per 100,000 people) induced by BTEX exposure in the outdoor air in Tehran were determined to be 180.21, 3.51, 2.07, and 0.04, respectively. The five highest attributable DALY rates in Tehran by district were observed in the districts 10 (2.60), 11 (2.43), 17 (2.41), 20 (2.32), and 9 (2.32), respectively. The corrective measures such as controlling road traffic and improving the quality of vehicles and gasoline in Tehran could reduce the burden of disease from BTEX along with the health effects of other outdoor air pollutants. [ABSTRACT FROM AUTHOR]

Styrene, Benzene, Toluene, Ethylbenzene, and Xylenes (SBTEX) are established neurotoxicants. These SBTEX are hazardous air pollutants (HAPs) and released from the petrochemical industry, combustion process, transport emission, and solvent usage sources. Although several SBTEX toxic assessment studies have been conducted, they have mainly relied on ambient measurements to estimate exposure and limiting their scope to specific locations and observational periods. To overcome these spatiotemporal limitations, an air quality modeling system over the U.S. Gulf region was created predicting the the spatially and temporally enhanced SBTEX modeling concentrations from May to September 2012. Due to the incompleteness of SBTEX in the official US EPA National Emission Inventory (NEI), Hazardous Air Pollutions Imputation (HAPI) program was used to identify and estimate the missing HAPs emissions. The improved emission data was processed to generate the chemically-speciated hourly gridded emission inputs for the Comprehensive Air Quality Model with Extensions (CAMx) chemical transport model to simulate the SBTEX concentrations over the Gulf modeling region. SBTEX pollutants were modeled using a "Reactive Tracer" feature in CAMx that accounts for their chemical and physical processes in the atmosphere. The data shows that the major SBTEX emissions in this region are contributed by mobile emission (45%), wildfire (30%), and industry (26%). Most SBTEX emissions are emitted during daytime hours (local time 14:00 -17:00), and the emission rate in the model domain is about 20 - 40 t hr-1, which is about 4 times higher than that in the night-time (local time 24:00 - 4:00, about 4 - 10 t hr-1). High concentrations of SBTEX (above 1 ppb) occurred near the cities close to the I-10 interstate highway (Houston, Beaumont, Lake Charles, Lafayette, Baton Rouge, New Orleans, and Mobile) and other metropolitan cities (Shreveport and Dallas). High Styrene concentrations were co-located with industrial sources, which contribute the most to the Styrene emissions. The HAPI program successfully estimated missing emissions of Styrene from the chemical industry. The change increased total Styrene emissions was increased by 22% resulting in maximum ambient concentrations increasing from 0.035 ppb to 1.75 ppb across the model domain. The predicted SBTEX concentrations with imputed emissions present good agreement with observational data, with a correlation coefficient (R) of 0.75 (0.46 to 0.77 for individual SBTEX species) and normalized mean bias (NMB) of -5.6% (-24.9% to 32.1% for individual SBTEX species), suggesting their value for supporting any SBTEX-related human health studies in the Gulf region. [ABSTRACT FROM AUTHOR]

The generation of aromatic benzene, toluene, and xylene (BTX) compounds from non-petroleum feedstocks is of particular interest for chemists in the eyes of sustainability. Herein, a novel synthesis of toluene catalyzed by GaN semiconductor nanowire arrays is reported. Using methane and methanol as starting materials, the GaN nanowire arrays can synergistically facilitate the facile generation of toluene under either photo-irradiation or thermal-conditions. The detailed computational studies unveiled different mechanisms involved for the photo- and thermal-toluene synthesis. [ABSTRACT FROM AUTHOR]

ObjectiveTo assess prenatal air toxics exposure and risk for childhood germ cell tumors (GCTs) by histological subtype (yolk sac tumor and teratoma).MethodsIn this case-control study, GCT cases less than 6 years (n = 243) identified from California Cancer Registry records were matched by birth year to cancer-free population controls (n = 147,100), 1984 to 2013. Routinely monitored air toxic exposures were linked to subjects' birth address. Logistic regression estimated GCT risks per interquartile range increase in exposure.ResultsPrenatal exposure to various highly-correlated, traffic-related air toxics during the second trimester increased GCT risk, particularly 1,3-butadiene (odds ratio [OR] = 1.51; 95% confidence interval [CI] = 1.01, 2.26) and meta/para-xylene (OR = 1.56; 95% CI = 1.10, 2.21). Analyses by subtype indicated elevated ORs for yolk sac tumors but not teratomas.ConclusionOur estimated ORs are consistent with positive associations between some prenatal traffic-related air toxics and GCT risk, notably yolk sac tumors.

The aim of introducing occupational exposure limits (OELs) is to use them as a risk management tool in order to protect workers’ health and well-being against harmful agents at the workplace. In this review we identify OELs for benzene, toluene, ethylbenzene, xylene (BTEX), and styrene concentrations in air and assess occupational exposure to these compounds through a systematic literature search of publications published in West Asian countries from 1980 to 2021. OELs for BTEX and styrene have been set in Iran and Turkey to levels similar to those in European countries and the US. The search yielded 49 full-text articles that cover studies of exposure assessment in six countries, but most (n=40) regard Iran. Average occupational exposure to benzene of workers in oil-related industries is higher than recommended OEL, while average occupational exposure to other compounds is lower than local OELs (where they exist). Currently, information about levels of occupational exposure to BTEX and styrene is insufficient in West Asian countries, which should be remedied through OEL regulation and application. Furthermore, coherent research is also needed to determine actual levels of occupational exposure, dose-responses, and the economic and technical capacity of local industries to address current issues.

The increase in the CO2 concentration in the atmosphere has caused a serious global climate problem. Aromatics are important intermediates in chemical production, and by utilizing CO2 in aromatic synthesis not only the effective utilization of CO2 can be realized, but also carbon emission reduction can be effectively achieved. Herein, a bifunctional catalyst prepared by physically mixing Y-doped ZnZrOx metal oxide with the zeolite ZSM-5 was applied to the synthesis of toluene and xylene by the alkylation of benzene using CO2 and H2. The bifunctional catalyst Y0.1/ZSM-5 showed the best reaction performance. 17.3% conversion of CO2, 30.8% conversion of benzene, and 71.6% selectivity of toluene and xylene were achieved. And 96.8% of the liquid-phase products were toluene and xylene. Based on the CO2-TPD, H2–D2 exchange, H2-TPR, EPR, XPS, and in situ DRIFTS results, a small amount of Y doping can effectively increase more oxygen vacancies on the surface of ZnZrOx to promote CO2 adsorption and activation. The activation of hydrogen was enhanced resulting from Y–Zn interactions. In the reaction pathway, Y doping accelerated the conversion of CO2 to HCOO* species to promote the reaction process, allowing more methanol to participate in the benzene alkylation reaction and further improving the CO2 and benzene conversion. [ABSTRACT FROM AUTHOR]

The municipal solid waste (MSW) landfill is recognized as an anthropogenic source of air pollutants that can have a negative impact on human health and the environment. Workers who work at the MSW landfill may be exposed to risk due to the inhalation of substances such as volatile organic compounds (VOCs). Although VOCs account for <1% in landfill gas, they are important because of the high level of toxicity associated with them. Regular monitoring of air quality and risk assessment provides important information in protecting the health of workers at the landfill. This study focuses on a health risk assessment related to VOCs (benzene, toluene and xylene) exposure via inhalation for workers at a landfill Banja Luka, Republic of Srpska, Bosnia and Herzegovina. Additionally, cancer risk and non-cancer risk of benzene, toluene and xylene of workers indicated that occupational exposures were above recommended standard. This implies that landfill workers are exposed to a significant health risk associated with inhalation exposure to VOCs. [ABSTRACT FROM AUTHOR]

Aromatization of light alkanes is pivotal for producing benzene, toluene, and xylene (BTX). However, achieving selective BTX production necessitates advancements in catalytic strategies. This study outlines a methodology to precisely control BTX species selectivity and distribution. The choice of active metal profoundly influences BTX product distribution over ZSM-5 catalysts. Mo/HZSM-5 facilitates n-butane dissociation to hydrocarbon intermediates, favoring benzene-rich products. In contrast, Ga/HZSM-5 enhances toluene and xylene production rates compared to Mo/HZSM-5. Intermediate composition on Mo/HZSM-5 significantly influences final selectivity, with paraffin-rich conditions and high methane conversion yielding benzene-rich products. Adjusting reaction conditions, such as methane recycle and temperature, further fine-tunes product distribution. [Display omitted] • Parameters affecting the selectivity of BTX were examined in n-butane aromatization. • Individual selectivity of BTX depends largely on the metal species. • In the case of Mo/HZSM-5, intermediate composition affects final BTX distribution. • The presence of methane and the reaction temperature also decides the BTX selectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ B-Mg dual-modified ZSM-5 zeolite with complex is designed for alkylation of benzene and methanol. • Abundant and tunable weak Brønsted/Lewis acid sites by isomorphic substitution of B-Mg. • The side reactions of MTO and benzene alkylation with ethylene are inhibited by weak LAS. • 4 %Mg@B2-HZM-5 exhibited lowest EB selectivity (5.3 % in C8) and robust stability (240 h, 20 h−1). High-efficiency production of toluene and xylene from benzene-methanol alkylation is a potential way to optimize the resource structure between petrochemical and coal chemical industry. Herein, the porosity and acidity of ZSM-5 zeolite have been successfully tailored by in-situ Mg- and B-isomorphous substitution. UV–VIS–DRS, FT-IR, NH 3 -TPD and Py-IR characterizations unveiled that B and Mg isomorphous substitution in the framework of ZSM-5 and the detachment of Mg from the framework during calcination can enable the abundant weak Brønsted/Lewis acidic sites and the reduction of strong acidic sites. Thanks to the appropriate acidic density, types and strength to inhibit the alkylation of benzene and ethylene, as well as large mesopore to facilitate the mass transfer, the optimized 4 %Mg@B2-HZM-5 exhibits the excellent alkylation performance of benzene and methanol with a X B of 50.5 %, S T of 52.2 %, S C8 of 36.8 %, S C9+ of 11.0 %, Y EBinC8 of 5.3 %, and robust stability (240 h) at high WHSV (20 h−1). The possible mechanism on 4 %Mg@B2-HZM-5 for benzene alkylation with methanol was also further discussed. This work provides an efficient strategy to modulate the porosity and acidity via B and Mg isomorphous dual substitution to achieve an improved catalytic performance in benzene alkylation with methanol. [ABSTRACT FROM AUTHOR]

The first comparative study of the surface behavior of four small aromatic molecules, benzene, toluene, p-xylene, and o-xylene, adsorbed on graphite at temperatures ≤30 K, is presented. Intermolecular interactions are shown to be important in determining the growth of the molecules on the graphite surface at low (monolayer) exposures. Repulsive intermolecular interactions dominate the behavior of benzene and toluene. By contrast, stronger interactions with the graphite surface are observed for the xylene isomers, with islanding observed for o-xylene. Multilayer desorption temperatures and energies increase with the size of the molecule, ranging from 45.5 to 59.5 kJ mol−1 for benzene and p-xylene, respectively. Reflection absorption infrared spectroscopy gives insight into the effects of thermal processing on the ordering of the molecules. Multilayer benzene, p-xylene, and o-xylene form crystalline structures following annealing of the ice. However, we do not observe an ordered structure for toluene in this study. The ordering of p-xylene shows a complex relationship dependent on both the annealing temperature and exposure. [ABSTRACT FROM AUTHOR]

Toxic gaseous organic air pollutants such as benzene, toluene, ethylbenzene, and xylene isomers (m, p, and o-x) (BTEX) are considered hazardous due to its adverse impacts on human health and on climate change. This review identifies the major research questions addressed so far and the research gap in research articles, published between 2001 and 2022, focusing on the ambient BTEX concentrations in different locations in India along with its sources, ozone formation potential (OFP), and associated health risks. The ambient levels of BTEX were also compared with those of other Asian countries. A comparison of ambient BTEX levels with different microenvironments in India is also presented. BTEX concentrations were found in the range of 30.95 to 317.18 µg m−3 and multi-fold higher in urban environments than those measured in the rural air. In most reported studies, the order of occurrence of BTEX compounds was toluene > benzene > xylene isomers > ethylbenzene and winter had higher concentrations than in other seasons, including summer. As far as BTEX levels in classified areas of urban environments are concerned, traffic locations have shown the highest BTEX concentrations, followed by residential, commercial, and industrial locations. OFP indicated that xylene isomers and toluene contributed to ozone formation. The major gaps in reported studies on BTEX measurement are (1) source apportionment; (2) impact on lower tropospheric chemistry, human health, and climate change; and (3) removal techniques from air. [ABSTRACT FROM AUTHOR]

Benzene, toluene, and xylenes (BTX) commonly co-exist. Exposure to individual components and BTX-rich mixtures can induce hematological effects. However, the hematological effects of long-term exposure to BTX are still unclear, and respective reference levels based on empirical evidence should be developed. We conducted a follow-up study in BTX-exposed petrochemical workers. Long-term exposure levels were quantified by measuring cumulative exposure (CE). Generalized weighted quantile sum (WQS) regression models and Benchmark Dose (BMD) Software were used to evaluate their combined effects and calculate their BMDs, respectively. Many hematologic parameters were significantly decreased at the four-year follow-up (p < 0.05). We found positive associations of CE levels of benzene, toluene, and xylene with the decline in monocyte counts, lymphocyte counts, and hematocrit, respectively (β > 0.010, Ptrend < 0.05). These associations were stronger in subjects with higher baseline parameters, males, drinkers, or overweight subjects (Pinteraction < 0.05). BTX had positive combined effects on the decline in monocyte counts, red-blood-cell counts, and hemoglobin concentrations (Ptrend for WQS indices < 0.05). The estimated BMDs for CE levels of benzene, toluene, and xylene were 2.138, 1.449, and 2.937 mg/m3 × year, respectively. Our study demonstrated the hematological effects of long-term BTX co-exposure and developed 8h-RELs of about 0.01 ppm based on their hematological effects. [ABSTRACT FROM AUTHOR]