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1.
Anal Bioanal Chem ; 412(8): 1769-1784, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32043201

RESUMO

Simultaneous speciation of benzenediol isomers (BDIs), 1,2-benzenediol (catechol, CC), 1,3-benzenediol (resorcinol, RS), and 1,4-benzenediol (hydroquinone, HQ), was investigated by differential pulse voltammetry (DPV) using a graphite paste electrode (GPE) modified with Prussian blue-polyaniline nanocomposite. The modified GPE showed good stability, sensitivity, and selectivity properties for all the three BDIs. Prussian blue-doped nanosized polyaniline (PBNS-PANI) was synthesized first by using mechanochemical reactions between aniline and ferric chloride hexahydrate as the oxidants and then followed by the addition of potassium hexacyanoferrate(II) in a solid-state and template-free technique. The material was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The DPV measurements are performed in phosphate electrolyte solution with pH 4.0 at a potential range of - 0.1 to 1.0 V. The proposed modified electrode displayed a strong, stable, and continuous three well-separated oxidation peaks towards electrooxidation at potentials 0.20, 0.31, and 0.76 V for HQ, CC, and RS, respectively. The calibration curves were linear from 1 to 350.5 µM for both HQ and CC, while for RS, it was from 2 to 350.5 µM. The limit of detection was determined to be 0.18, 0.01, and 0.02 µM for HQ, CC, and RS, respectively. The analytical performance of the PBNS-PANI/GPE has been evaluated for simultaneous determination of HQ, CC, and RS in creek water, commercial hair dye, and skin whitening cream samples with satisfactory recoveries between 90 and 106%. Overall, we demonstrated that the presence of NS-PANI and PB resulted in a large redox-active surface area that enabled a promising analytical platform for simultaneous detection of BDIs. Graphical abstract.


Assuntos
Compostos de Anilina/química , Derivados de Benzeno/análise , Ferrocianetos/química , Nanoestruturas/química , Derivados de Benzeno/química , Calibragem , Eletrodos , Humanos , Concentração de Íons de Hidrogênio , Isomerismo , Cinética , Limite de Detecção , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Chemosphere ; 242: 125281, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896191

RESUMO

In this study, the potential of pulverized waste tires (PWTs), either on their own or mixed with soil (well graded sand), to act as adsorptive fill materials was evaluated by conducting laboratory tests for accessing their adsorption and geotechnical properties. PWT (0, 5, 10, 15, 25, and 100 wt%) was mixed with soil to evaluate the removal of benzene, toluene, ethylbenzene, and xylene (BTEX) components and two heavy metal ions (Pb2+ and Cu2+). Adsorption batch tests were performed to determine the equilibrium sorption capacity of each mixture. Subsequently, compaction, direct shear, and consolidation tests were performed to establish their geotechnical properties. The results showed that BTEX had the strongest affinity based on the uptake capacity by the soil-PWT mixtures. The adsorption of BTEX increased for greater PWT content, with pure PWT having the highest adsorption capacity toward BTEX removal: uptake capacities for xylene, ethylbenzene, toluene, and benzene were 526, 377, 207 and 127 µg/g sorbent, respectively. Heavy metal removal was increased by increasing the amount of PWT up to 10 wt%, and then decreased beyond this ratio. Compacted soil-PWT mixtures comprising 5-25 wt% PWT have relatively low dry unit weight, low compressibility, adequate shear capacity for many load-bearing field applications, and satisfactory adsorption of organic/inorganic contaminants, such that they could also be used as adsorptive fill materials.


Assuntos
Derivados de Benzeno/análise , Metais Pesados/análise , Poluentes do Solo/análise , Resíduos Sólidos/análise , Adsorção , Benzeno/análise , Modelos Teóricos , Eliminação de Resíduos , República da Coreia , Solo/química , Tolueno/análise , Xilenos/análise
3.
Environ Pollut ; 255(Pt 1): 113100, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31542674

RESUMO

Diesel-fueled buses have been replaced by Compressed Natural Gas (CNG) to minimize the high level of emissions in urban areas. However, differences in indoor exposure levels to Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in those vehicles have not been investigated so far. The primary aim of this study was to determine if passengers are exposed to different BTEX levels when using buses powered by CNG or by diesel, and further explore if indoor levels are influenced by external air quality. For this purpose, BTEX air concentrations were measured in bus cabins (CNG and diesel), parking stations and in a background urban area using passive air samplers. Results showed that BTEX concentrations inside vehicles were higher than outside, but no significant differences were found between buses powered by CNG or by diesel. In CNG vehicles, high and significant positive correlation was found between benzene and the number of journeys in the same route (rs = 0.786, p < 0.05), vehicle operating time (rs = 0.738, p < 0.05), exposure time (rs = 0.714, p < 0.05) and exposure index (rs = 0.738, p < 0.05), but this was not observed for diesel vehicles. Benzene in bus cabins was found to be significantly below reference value for human health protection. However, excepting p-xylene, all other aromatic pollutants have a mean concentration significantly above the lowest effect level (p ≤ 0.002 for all comparisons). Additionally, higher BTEX levels in cabin buses than in outdoor air suggest the presence of other emission sources in indoor cabins. These findings emphasize the need for further studies to fully characterize indoor emission sources in order to minimize the negative impact of BTEX exposure to human health.


Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Gás Natural/toxicidade , Tolueno/análise , Emissões de Veículos/análise , Xilenos/análise , Poluentes Atmosféricos/análise , Poluição do Ar , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental/métodos , Humanos , Veículos Automotores
4.
Chemosphere ; 237: 124451, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31394440

RESUMO

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of BTEX in Kuala Lumpur City Centre, Kuala Terengganu, Kota Kinabalu and Fraser Hill were conducted using Online Gas Chromatograph. For comparison, BTEX at selected hotspot locations were determined by active sampling method using sorbent tubes and Thermal Desorption Gas Chromatography Mass Spectrometry. The hazard quotient (HQ) for non-carcinogenic and the life-time cancer risk (LTCR) of BTEX were calculated using the United States Environmental Protection Agency (USEPA) health risk assessment (HRA) methods. The results showed that the highest total BTEX concentrations using continuous monitoring were recorded in the Kuala Lumpur City Centre (49.56 ±â€¯23.71 µg/m3). Toluene was the most dominant among the BTEX compounds. The average concentrations of benzene ranged from 0.69 ±â€¯0.45 µg/m3 to 6.20 ±â€¯3.51 µg/m3. Measurements using active sampling showed that BTEX concentrations dominated at the roadside (193.11 ±â€¯114.57 µg/m3) in comparison to petrol station (73.08 ±â€¯30.41 µg/m3), petrochemical industry (32.10 ±â€¯13.13 µg/m3) and airport (25.30 ±â€¯6.17 µg/m3). Strong correlations among BTEX compounds (p<0.01, r>0.7) at Kuala Lumpur City Centre showed that BTEX compounds originated from similar sources. The values of HQ at all stations were <1 indicating the non-carcinogenic risk are negligible and do not pose threats to human health. The LTCR value based on benzene inhalation (1.59 × 10-5) at Kuala Lumpur City Centre were between 1 × 10-4 and 1 × 10-5, representing a probable carcinogenic risk.


Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Monitoramento Ambiental/métodos , Medição de Risco , Tolueno/análise , Xilenos/análise , Benzeno/toxicidade , Derivados de Benzeno/toxicidade , Carcinógenos/análise , Carcinógenos/toxicidade , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Malásia , Tolueno/toxicidade , Xilenos/toxicidade
6.
Environ Sci Process Impacts ; 21(7): 1193-1203, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31204424

RESUMO

Coupling of chemical oxidation using persulfate with bioremediation has been proposed as a method to increase remedial efficacy at petroleum hydrocarbon contaminated sites. To support this integrated treatment approach, an understanding of persulfate impact on the indigenous microbial community is necessary for system design. As sulfate-reducing bacteria (SRB) are active in most aquifer systems and can utilize the sulfate generated from the degradation of persulfate, this study assessed the impact on SRB and the supporting anaerobic microbial community when exposed to persulfate in a continuous flow system. A series of bioreactors (1000 L) packed with anaerobic aquifer material were operated for an 8 month acclimatization period before being continuously subjected to benzene, toluene, ethylbenzene and xylenes (total BTEX 3 mg L-1). After 2 months, the bioreactors were then exposed to an unactivated persulfate solution (20 g L-1), or an alkaline-activated persulfate solution (20 g L-1, pH 12) then effluent-sampled for 60 days following. A combination of culture and molecular-based techniques were used to monitor SRB presence and structural profiles in the anaerobic SRB-specific and broader microbial community. Post-exposure, the rate of BTEX mass removal remained below pre-exposure values; however, trends suggest that full recovery would be expected. Rebound of SRB-specific and the associated microbial community to pre-exposure levels were observed in all exposed bioreactors. Structural community profiles identified recovery in both microbial species and diversity indices. Findings from this investigation demonstrate robustness of SRB in the presence of a supporting microbial community and, thus, are suitable organisms for target use during bioremediation in an integrated system with persulfate.


Assuntos
Derivados de Benzeno/análise , Reatores Biológicos/microbiologia , Desulfovibrio/crescimento & desenvolvimento , Água Subterrânea/química , Microbiota , Sulfatos/química , Poluentes Químicos da Água/análise , Anaerobiose , Biodegradação Ambiental , Oxirredução
7.
Sci Total Environ ; 659: 1090-1099, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31096324

RESUMO

The hazardous air pollutants like benzene, toluene, ethylbenzene and xylene (BTEX) are considered as toxic because of their role in ozone formation and adverse effects on human health. Owing to this, the present study was carried out at six spatially distributed sites in Delhi from November 2017- June 2018. Activated charcoal tubes were used to collect samples of BTEX and were further analyzed using GC-FID. The minimum BTEX concentration was found at institutional site (9.94 µg/m3) and maximum at roadside site (103.12 µg/m3) with the average of 46.66 µg/m3. Also, the levels of BTEX were 1.18-1.74 times higher during rush hours as compared to non-rush hours. The high T/B ratio (2.26-3.41) observed is the indication of the traffic-originated sources of emission. The cancer risks calculated for benzene at probability 0.50 ranged as 1.29E-06 - 1.80E-05, whereas 4.09E-06 - 3.40E-05 at probability 0.95, which were higher than the acceptable value of 1.0E-06. The non-cancer health risks in terms of hazard index were observed less than unity i.e. within acceptable limit. The total ozone formation potential (OFP) was obtained as 207.51 ±â€¯123.40 µg/m3 with maximum potential by toluene. Such high levels of BTEX, cancer risks and OFP obtained in the study especially at roadside and connectivity hub are harmful for people residing near these areas, and also to large commuters, who are exposed to such emissions during travelling.


Assuntos
Poluentes Atmosféricos/análise , Exposição Ambiental/estatística & dados numéricos , Ozônio/análise , Benzeno/análise , Derivados de Benzeno/análise , Monitoramento Ambiental , Humanos , Índia , Medição de Risco , Estações do Ano , Tolueno/análise , Xilenos/análise
8.
Environ Monit Assess ; 191(5): 286, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30997562

RESUMO

Benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations were measured in beauty salons (BS) and in the urine of the beauty practitioners and a control group. Indoor and outdoor concentrations of BTEX were measured in 36 randomly selected salons. Before- and after-shift urinary BTEX were measured from one female non-smoker employee in each salon, and repeated three times. Clinical symptoms in that beautician were assessed by a physician. Thirty-six unexposed women were included as the control group. Cancer and non-cancer risks of exposure were assessed using deterministic and stochastic methods. Average indoor concentrations of BTEX were higher than those in the ambient air. Urinary BTEX concentrations in the beauty practitioners were significantly higher than in the control group. Linear regression showed that 77% of urinary benzene and toluene variations can be explained by their airborne concentrations. A positive significant relationship was found between age and urinary BTEX concentrations. Although the BTEX cancer and non-cancer risks were not significant, BTEX led to irritation of the eyes, throat, lung, and nose. In addition, toluene caused menstrual disorders among beauty practitioners. These results suggest that it is essential to decrease the exposure of beauty practitioners to BTEX compounds.


Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Tolueno/análise , Xilenos/análise , Poluentes Atmosféricos/análise , Beleza , Monitoramento Ambiental/métodos , Feminino , Humanos , Modelos Lineares , Medição de Risco/métodos
9.
Environ Pollut ; 249: 518-526, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30933751

RESUMO

Nail salon technicians face chronic exposure to volatile organic compounds (VOCs), which can lead to adverse health outcomes including cancer. In this study, indoor levels of formaldehyde, as well as benzene, toluene, ethylbenzene and xylene, were measured in 6 Colorado nail salons. Personal exposure VOC measurements and health questionnaires (n = 20) were also performed; questionnaires included employee demographics, health symptoms experienced, and protective equipment used. Cancer slope factors from the United States Environmental Protection Agency (US EPA) and anthropometric data from the Centers for Disease Control and Prevention were then used to estimate cancer risk for workers, assuming 20-yr exposures to concentrations of benzene and formaldehyde reported here. Results show that 70% of surveyed workers experienced at least one health issue related to their employment, with many reporting multiple related symptoms. Indoor concentrations of formaldehyde ranged from 5.32 to 20.6 µg m-3, across all 6 salons. Indoor concentrations of toluene ranged from 26.7 to 816 µg m-3, followed by benzene (3.13-51.8 µg m-3), xylenes (5.16-34.6 µg m-3), and ethylbenzene (1.65-9.52 µg m-3). Formaldehyde levels measured in one salon exceeded the Recommended Exposure Limit from the National Institute for Occupational Safety and Health. Cancer risk estimates from formaldehyde exposure exceeded the US EPA de minimis risk level (1 × 10-6) for squamous cell carcinoma, nasopharyngeal cancer, Hodgkin's lymphoma, and leukemia; leukemia risk exceeded 1 × 10-4 in one salon. The average leukemia risk from benzene exposure also exceeded the US EPA de minimis risk level for all demographic categories modeled. In general, concentrations of aromatic compounds measured here were comparable to those measured in studies of oil refinery and auto garage workers. Cancer risk models determined that 20-yr exposure to formaldehyde and benzene concentrations measured in this study will significantly increase worker's risk of developing cancer in their lifetime.


Assuntos
Poluentes Atmosféricos/análise , Indústria da Beleza , Monitoramento Ambiental/métodos , Exposição Ocupacional/análise , Compostos Orgânicos Voláteis/análise , Adulto , Benzeno/análise , Derivados de Benzeno/análise , Colorado , Formaldeído/efeitos adversos , Formaldeído/análise , Humanos , Neoplasias Nasofaríngeas/induzido quimicamente , Hipersensibilidade Respiratória , Inquéritos e Questionários , Tolueno/análise , Estados Unidos , United States Environmental Protection Agency , Xilenos/análise
10.
Artigo em Inglês | MEDLINE | ID: mdl-30875733

RESUMO

Public concern regarding the use of products with chemicals has increased in Korea, following reports indicating that hazardous chemicals in products, such as disinfectants, can cause fatal lung disease. Despite the widespread use of car colorant products, little is known regarding their potential health risks. The purpose of this study was to determine the potential health risks of substances that exist in car colorant products. Thirteen car colorant products were purchased from the Korean market and 15 commonly used chemicals were analyzed. Exposure and risk assessments were conducted in two assessment stages (screening and refined). The analysis showed that all of the examined products contained toluene, ethylbenzene, and xylene. The maximum concentration of toluene was 52.5%, with a median concentration of 10.8%. Tier 1 (screening) assessment showed that four chemicals (toluene, ethylbenzene, xylene, and 2-butoxyethanol) may pose health risks, but tier 2 (refined) assessment showed that these chemicals do not pose any risk. However, these chemicals were present in all of the examined products, and government regulations did not control their concentrations in these products. Therefore, we suggest that levels of toluene, ethylbenzene, and xylene in car colorant products should be regulated to protect public health.


Assuntos
Automóveis , Corantes/efeitos adversos , Derivados de Benzeno/efeitos adversos , Derivados de Benzeno/análise , Humanos , República da Coreia , Medição de Risco , Tolueno/efeitos adversos , Tolueno/análise , Xilenos/efeitos adversos , Xilenos/análise
11.
Chemosphere ; 224: 85-92, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30818198

RESUMO

Infants and children under 6 years old spend most of daily time in Child Care Centers (CCCs), especially in the tropical regions like Singapore. Environmental exposure and associated risk during this early critical developmental stage is of great public concern. In this study, seven representative volatile organic compounds (VOCs) and five typical phthalates were analyzed in the indoor and outdoor air samples collected from 32 Singapore CCCs. The median of total VOC and phthalate concentration in indoor air was 19.03 and 5.41 µg m-3; respectively. For both indoors and outdoors environment, benzene, toluene and xylene were the dominant VOC contributors (more than 68%). For indoor air phthalates, di(2-ethylhexyl) phthalate and di-butyl phthalate (DBP) accounts for 60-76%. The level of both VOCs and phthalates in indoor environment was significantly higher than that in outdoor, with an average indoor/outdoor ratio of 1.24 and 1.45; respectively. A strong correlation (r > 0.50, p < 0.05) was observed between indoor and outdoor air compounds. VOC and phthalate levels have no significant difference between CCCs with split-unit and centrally ventilated air conditioners. Monte Carlo simulation was used to estimate exposure uncertainty and variability for the risk assessment. Overall, the concentrations of VOC were below the healthy reference values from either EPA Integrated Risk Information System (IRIS) or Singapore guideline. However, similar to other countries' report, benzene, DBP, ethylbenzene and naphthalene were at levels that could exceed the stringent standards such as Office of Environmental Health Hazard Assessment (OEHHA) cancer and reproductive health-based benchmarks.


Assuntos
Poluentes Atmosféricos , Creches , Ácidos Ftálicos , Compostos Orgânicos Voláteis , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Benzeno/análise , Derivados de Benzeno/análise , Pré-Escolar , Exposição Ambiental/análise , Humanos , Lactente , Medição de Risco , Singapura , Tolueno , Compostos Orgânicos Voláteis/análise , Xilenos/análise
12.
Chemosphere ; 224: 743-750, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30851526

RESUMO

As a typical class of environmental endocrine disruptors, bisphenol A poses a potential threat to the sustainable survival and reproduction of living beings and human beings. In this study, the interaction between Trametes versicolor laccase and bisphenol A (BPA) was studied by molecular docking simulation, and the catalytic degradation of BPA was verified by experiments. The conditions for the laccase production of T. versicolor were optimized by orthogonal design, and the degradation of BPA was studied using its crude enzyme solution. The optimum degradation conditions were obtained by response surface methodology (RSM). Ultimately, the transformation products after 3 and 6 h of reaction were detected by gas chromatography-mass spectrometry. Docking results demonstrated that the reaction between laccase and BPA was spontaneous, and the degradation rate in 24 h reached 88.76%. RSM results showed that the highest BPA degradation rate of 97.68% was reached after 1 h reaction at 44.6 °C, 5 mg/L initial BPA concentration, and pH 5.20. The intermediate products of BPA catalyzed by laccase included ethylbenzene, p-xylene, and cyclohexanone 1-methyl-4-isopropenyl-2-cyclohexenol. This finding reveals that BPA degradation by the crude laccase from T. versicolor starts from the C atoms between two benzene rings that connect BPA. Compared with expensive pure enzyme, the crude laccase solution prepared by T. versicolor showed greater efficiency in BPA degradation. This work provides theoretical references and experimental methods for the biological processing of harmful pollutants.


Assuntos
Compostos Benzidrílicos/metabolismo , Biodegradação Ambiental , Disruptores Endócrinos/metabolismo , Lacase/metabolismo , Fenóis/metabolismo , Trametes/metabolismo , Agaricales/metabolismo , Derivados de Benzeno/análise , Catálise , Poluentes Ambientais/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Simulação de Acoplamento Molecular , Trametes/enzimologia , Xilenos/análise
13.
Sud Med Ekspert ; 62(1): 36-42, 2019.
Artigo em Russo | MEDLINE | ID: mdl-30724892

RESUMO

The present study was designed to elucidate the character of the distribution of 2,4- and 2,6-di-tret-butylhydroxybenzenes (2,4-DTBHOB and 2,6-DTBHOB respectively) in the body of the warm-blooded animals (rats) following the administration of the three-fold LD50 dose into the stomach. Both 2,4-DTBHOB and 2,6-DTBHOB were extracted from the blood and the organs of the perished animals by means of two-fold incubation of the sampled tissues in ethyl acetate with the subsequent purification of the isolates by passing the extracts through a L 40/100 mcm silicagel column using hexane:dioxane (8.5:1.5) for 2,4-DTBHOB and hexane:dioxane (97.5:2.5) for 2,6-DTBHOB as eluants. The compounds of interest were identified and quantified by means of TLC, HPLC, and UV-spectrometry. The study has shown that both 2,4-DTBHOB and 2,6-DTBHOB were present in the organs and blood of the poisoned animals in the unmetabolized form. Their largest amounts (mg/100 g) were found in the contents of the stomach, the small intestines with the contents and in the spleen.


Assuntos
Derivados de Benzeno/análise , Toxicologia Forense , Animais , Intestino Delgado/química , Ratos , Baço/química , Estômago/química , Distribuição Tecidual
14.
Artigo em Inglês | MEDLINE | ID: mdl-30791518

RESUMO

Trimethylbenzene (TMB) isomers (1,2,3-TMB, 1,2,4-TMB, and 1,3,5-TMB) are often used as conservative tracers in anaerobic, contaminated aquifers for assessing BTEX (benzene, toluene, ethylbenzene, xylenes) biodegradation at field sites. However, uncertainties exist about the behavior of these compounds under anaerobic conditions. For this reason, the influence of various parameters (temperature, residence time) on the biodegradability of TMB isomers was investigated under denitrifying and sulfate-reducing conditions in microcosms and 1D-column experiments. Soil and groundwater contaminated with a cocktail of aromatic hydrocarbons including the TMB isomers, both collected from an industrial site in Berlin, Germany, were used for the laboratory investigations. A continuous and complete biodegradation of 1,3,5-TMB and 1,2,4-TMB under denitrifying conditions was observed independent of realized temperature (10⁻20 °C) and residence time. Biodegradation of 1,2,3-TMB started after longer lag-phases and was not continuous over the whole experimental period; a strong dependence on temperature and residence time was identified. The biodegradability of all TMB isomers under sulfate-reducing conditions was continuous and complete at higher temperatures (20 °C), whereas no degradation was observed for lower temperatures (10 °C). First-order biodegradation rate constants ranged from 0.05 to 0.21 d-1 for 1,3,5-TMB and 1,2,4-TMB and from 0.01 to 0.11 d-1 for 1,2,3-TMB.


Assuntos
Derivados de Benzeno/química , Biodegradação Ambiental , Derivados de Benzeno/análise , Alemanha , Água Subterrânea/química , Isomerismo , Poluentes do Solo/análise , Temperatura Ambiente , Poluentes Químicos da Água/análise
15.
Environ Pollut ; 247: 607-617, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30711816

RESUMO

This study characterized spatio-temporal variations in the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in the vicinity of gas and compressed natural gas (CNG) stations in Tehran, Iran. Health risk assessment (HRA) was computed using Monte Carlo simulations (MCS) for evaluating inhalation lifetime cancer risk (LTCR), the hazard quotient (HQ), and sensitivity analysis (SA) for BTEX exposure in different age groups (birth to <81) and as a function of distance (0-250 m) from the center of the stations. For all monitoring stations, the average values of benzene, toluene, ethylbenzene, and xylene in winter were 466.09 ±â€¯132.25, 873.13 ±â€¯233.51, 493.05 ±â€¯141.22, and 910.57 ±â€¯145.40 µg m-3, respectively. The mean wintertime ratios of T/B for the 12 stations ranged from 1.69 to 2.04. Furthermore, there was no significant relationship between the concentration of BTEX with either the specific month or distance from the center of stations (p > 0.05). Factors promoting BTEX formation in the study region were fuel evaporation and gas/CNG station emissions. The LTCRs for the target compounds in the winter for different age groups and distances from the center of stations was limited to 2.11 × 10-4 to 1.82 × 10-3 and 2.30 × 10-4 to 2.01 × 10-3, respectively, which exceeded proposed values by U.S. EPA. Moreover, the HQs for BTEX for three age groups and distances were limited to between 2.89 × 10-5 and 9.33 × 10-2, which were lower than the acceptable limit (HQs < 1). The results of this work are applicable to similar areas that are heavily populated with vehicular traffic. This study motivates a closer look at mitigation strategies to limit the health effects of carcinogenic emissions such as benzene and ethylbenzene from gas/CNG stations.


Assuntos
Poluentes Atmosféricos/análise , Exposição Ambiental/estatística & dados numéricos , Poluição Ambiental/estatística & dados numéricos , Poluentes Atmosféricos/toxicidade , Benzeno/análise , Derivados de Benzeno/análise , Carcinógenos/análise , Exposição Ambiental/análise , Monitoramento Ambiental/métodos , Poluição Ambiental/análise , Humanos , Irã (Geográfico) , Medição de Risco , Estações do Ano , Tolueno/análise , Xilenos/análise
16.
Chemosphere ; 221: 226-234, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30640005

RESUMO

Indoor potted plants are able to remove volatile organic compounds (VOC) from air, but only few studies have investigated the removal of compounds in mixtures. Here, we present a non-targeted pixel-based fingerprinting analysis documenting the removal of a complex mixture of gasoline VOCs by Hedera helix under dynamic chamber conditions allowing for air exchange and continuous gasoline exposure. For 15 days, the entire potted plant was exposed to gasoline; subsequently, the epigeous plant parts were removed and the soil microcosm (i.e. soil, plant roots and microorganisms) was exposed to gasoline for another eight days. Quantitative analysis was performed for heptane, 3-methylhexane, toluene, ethylbenzene and m,p-xylenes, and the CHEMSIC method (CHEMometric analysis of Selected Ion Chromatograms) was used for non-targeted pixel-based fingerprinting analysis. The quantitative analysis demonstrated that the presence of potted plants or pots without epigeous plant parts led to a reduction of selected VOCs by 16.7-22.6%. The CHEMSIC method confirmed this and revealed that all gasoline VOCs were reduced in concentration when H. helix was present. The estimate for the total VOC removal was in the range of 11-32%. The removal was highest for samples where the epigeous plant parts were absent and compounds known to be hard to degrade by microorganisms such as dimethylcyclopentanes were removed the least compared to compounds more easily degraded by microorganisms such as heptane when epigeous plant parts were removed. All findings support the conclusion that the soil microcosm was the main responsible for the removal of VOCs.


Assuntos
Gasolina , Plantas/metabolismo , Compostos Orgânicos Voláteis/isolamento & purificação , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Derivados de Benzeno/análise , Solo/química , Microbiologia do Solo , Compostos Orgânicos Voláteis/análise
17.
Chemosphere ; 220: 651-657, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30599323

RESUMO

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 (EC50) 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.


Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Biodegradação Ambiental , Bioensaio , Solo/química , Tolueno/análise , Xilenos/análise , Bactérias/metabolismo , Oxirredução , Poluentes do Solo/análise , Enxofre
18.
Nat Prod Res ; 33(3): 435-438, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29553803

RESUMO

Emitted scent volatile profile of an orchid species Zygopetalum maculatum was studied using dynamic headspace sampling technique with four different adsorbent matrices, namely Porapak Type Q polymer (mesh size: 80/100), Tenax (mesh size: 60/80), activated charcoal and graphite. In addition, developmental variations in scent emissions and endogenous volatile levels were also investigated. Gas chromatography-mass spectrometry analysis revealed the presence of 21 volatile compounds in the headspace, which was predominantly enriched with benzenoid compounds. Among these benzenoids, o-diethylbenzene and p-diethylbenzene were the major compounds followed by benzyl acetate and methyl salicylate. Among the phenylpropanoid compounds, 2-phenylethyl acetate was the major volatile. However, as compared to benzenoids, the quantity was much lesser, indicating the inclination of phenylalanine flux towards benzenoid pathway. The outcome of this study has the implications in enhancing fragrance and vase life of orchids of the Sikkim Himalaya region and thus may further help to meet the growing market demand.


Assuntos
Odorantes/análise , Orchidaceae/química , Compostos Orgânicos Voláteis/isolamento & purificação , Adsorção , Derivados de Benzeno/análise , Derivados de Benzeno/química , Derivados de Benzeno/isolamento & purificação , Carvão Vegetal , Flores/química , Cromatografia Gasosa-Espectrometria de Massas , Siquim , Compostos Orgânicos Voláteis/química
19.
Arch Environ Occup Health ; 74(4): 197-205, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29319452

RESUMO

Few studies have evaluated airborne exposures to benzene, toluene, ethylbenzene, and xylenes (BTEX) during operation of two-stroke and four-stroke small engines, such as those in lawn maintenance equipment. Full-shift, 8-hour personal samples were collected during a simulation study to characterize yard maintenance activities including mowing, trimming, and fueling. Short-term, 15-minute personal samples were collected to separately evaluate mowing and trimming exposures. Mean 8-hour time weighted average (TWA) BTEX concentrations were 2.3, 5.8, 0.91, and 4.6 ppb, respectively (n = 2). Mean 15-minute TWA BTEX concentrations were 1.6, 1.8, 0.22, and 1.3 ppb, respectively, during mowing and 1.2, 3.6, 0.68, and 3.3 ppb, respectively, during trimming (n = 3 per task). Measured BTEX concentrations during fueling were 20-110, 61-310, 8-41, and 40-203 ppb, respectively (n = 2, duration 2-3 minutes). These exposure concentrations were well below applicable US occupational exposure limits.


Assuntos
Derivados de Benzeno/análise , Monitoramento Ambiental , Exposição Ocupacional/análise , Tolueno/análise , Xilenos/análise , Poluentes Atmosféricos , Irã (Geográfico)
20.
Food Chem ; 273: 45-51, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30292373

RESUMO

This work evaluated the presence of contaminants in stored rainwater in 36 polyethylene tanks installed in two rural communities of the semiarid of Bahia, Brazil. Carbonyl compounds were analyzed by High Performance Liquid Chromatography (HPLC-UV), BTEX (Benzene, Toluene, Ethylbenzene and Xylenes) by gas chromatoghaphy (GC-FID), and trace elements by inductively coupled plasma optical emission spectrometry (ICP-OES). Seven carbonyl compounds were quantified including acrolein (<3-115 µg L-1), which is considered a potent mutagenic agent, above the potability limit in 75% of the cases. Trace elements such as copper, zinc, barium, aluminum and lead, more frequently found, were also quantified, and lead (<0,56-99 µg L-1) was above the tolerable limit for drinking water of 10 µg L-1 in 73% of the cases. The results show that the stored water in polyethylene cisterns in the Brazilian semiarid region does not present satisfactory conditions for human consumption.


Assuntos
Água Potável/análise , Polietileno , Poluentes Químicos da Água/análise , Acroleína/análise , Benzeno/análise , Derivados de Benzeno/análise , Brasil , Cromatografia Gasosa/métodos , Cromatografia Líquida de Alta Pressão/métodos , Água Potável/química , Armazenamento de Alimentos/instrumentação , Armazenamento de Alimentos/métodos , Metais/análise , Análise Espectral/métodos , Tolueno/análise , Xilenos/análise
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