Benzene, Toluene, Ethylbenzene, Xylenes Research Articles

The effect of temperature on hydrocarbon profiles and the microbial community composition in North Saskatchewan River water during mesoscale tank tests of diluted bitumen spills

Despite many studies of diluted bitumen (DB) behavior during spills in saltwater, limited information is available on DB behavior in fresh water. This study examined the collective weathering processes on changes of fresh DB spilled in the North Saskatchewan River water and sediment mixture in a mesoscale spill tank under average air/water temperatures of 14 °C/15 °C and 6 °C/2 °C. Temporal changes of the hydrocarbon and microbial community compositions in the water column were assessed during the two 35-day tests under intermittent wave action. The contents of total organic carbon (TOC), benzene/toluene/ethylbenzene/xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAHs) in water decreased with time during both tests. The final contents remained at higher values in warm water (15 °C) than in cold water (2 °C) after the collective weathering processes. A quick response of the main phyla, Proteobacteria and Actinobacteria, was observed, where the members of Proteobacteria enriched during both DB spills. In contrast, the members of Actinobacteria reduced with time. The microbial shifts coincided with the changes of PAHs in the waters at both temperatures. A comparison of the physical properties and chemical compositions of fresh and weathered DBs at both temperatures showed that the oil had undergone weathering that increased oil density and viscosity due to losing the light oil fraction with boiling points < 204 °C and emulsifying with water. This corresponded to losses of 19.0 wt% and 17.2 wt% of the fresh DB at 15 °C and 2 °C tests, respectively. For organic compounds in the DB with boiling points > 204 °C, there were small losses of saturates and 2- & 3-ring PAH aromatics (more during the 15 °C test than the 2 °C test), and negligible losses in the subfractions of resins and asphaltenes by the ends of the tests. <1.0 wt% of the DB was recovered from the bottom sediment, regardless of the temperature.

Contaminant characterization at pesticide production sites in the Yangtze River Delta: Residue, distribution, and environmental risk

The Yangtze River Delta (YRD) is the largest pesticide-producing region in the world. Contamination of pesticide production sites has always been a focus of public attention. Twenty pesticide production sites in YRD were selected to analyze the residue, distribution, and environmental risk of organic contaminants in soil and groundwater. A total of 194 organic chemicals were detected in all soil and groundwater samples from the 20 sites. Eighty-eight constituents of concern (COCs) exceeded the comparison values of Regional Screening Levels (RSLs), and 80 % exceeded the RSLs by more than five times. The toxic effects of COCs in soil and groundwater were dominated by the carcinogenic risk, referred as “non-threshold”. Benzene toluene ethylbenzene & xylene (BTEX) and chloroaliphatic hydrocarbons (CAHs) were the most prevalent at pesticide sites in YRD rather than pesticides, followed by chlorobenzene, chlorophenols, and polycyclic aromatic hydrocarbons (PAHs). CAHs and BTEX could penetrate up to 24 m, while the others were primarily limited to 12 m. Most pesticide production sites showed a great contamination depth of >8 m, some even deeper than 20 m, posing a great risk of contamination to the confined aquifer. Due to the close interconnection of soil with water bodies, the shallow groundwater and adjacent surface water resources are also susceptible to suffering from environmental risk. More than half of the pesticide production sites in the YRD consist primarily of low-permeable clay layers, making in-situ contamination remediation difficult. This study provides a basis for developing remediation technology for pesticide sites in YRD and an ecological reference for further cleaning production and green manufacturing in the pesticide industry.

Synthetic Biology Toolbox, Including a Single-Plasmid CRISPR-Cas9 System to Biologically Engineer the Electrogenic, Metal-Resistant Bacterium Cupriavidus metallidurans CH34.

Cupriavidus metallidurans CH34 exhibits extraordinary metabolic versatility, including chemolithoautotrophic growth; degradation of BTEX (benzene, toluene, ethylbenzene, xylene); high resistance to numerous metals; biomineralization of gold, platinum, silver, and uranium; and accumulation of polyhydroxybutyrate (PHB). These qualities make it a valuable host for biotechnological applications such as bioremediation, bioprocessing, and the generation of bioelectricity in microbial fuel cells (MFCs). However, the lack of genetic tools for strain development and studying its fundamental physiology represents a bottleneck to boosting its commercial applications. In this study, inducible and constitutive promoter libraries were built and characterized, providing the first comprehensive list of biological parts that can be used to regulate protein expression and optimize the CRISPR-Cas9 genome editing tools for this host. A single-plasmid CRISPR-Cas9 system that can be delivered by both conjugation and electroporation was developed, and its efficiency was demonstrated by successfully targeting the pyrE locus. The CRISPR-Cas9 system was next used to target candidate genes encoding type IV pili, hypothesized by us to be involved in extracellular electron transfer (EET) in this organism. Single and double deletion strains (ΔpilA, ΔpilE, and ΔpilAE) were successfully generated. Additionally, the CRISPR-Cas9 tool was validated for constructing genomic insertions (ΔpilAE::gfp and ΔpilAE::λPrgfp). Finally, as type IV pili are believed to play an important role in extracellular electron transfer to solid surfaces, C. metallidurans CH34 ΔpilAE was further studied by means of cyclic voltammetry using disposable screen-printed carbon electrodes. Under these conditions, we demonstrated that C. metallidurans CH34 could generate extracellular currents; however, no difference in the intensity of the current peaks was found in the ΔpilAE double deletion strain when compared to the wild type. This finding suggests that the deleted type IV pili candidate genes are not involved in extracellular electron transfer under these conditions. Nevertheless, these experiments revealed the presence of different redox centers likely to be involved in both mediated electron transfer (MET) and direct electron transfer (DET), the first interpretation of extracellular electron transfer mechanisms in C. metallidurans CH34.

Occupational exposure to BTEX and styrene in West Asian countries: a brief review of current state and limits.

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.

Soil and groundwater remediation proposal for hydrocarbons in a tropical aquifer

This paper deals with a proposal for the remediation of soils and groundwater contaminated with hydrocarbons in a tropical aquifer, due to leaks from underground tanks in a gas station in Venezuela. The hydrocarbon measured values such as TPHs (Total Petroleum Hydrocarbons) and BTEX (Benzene, Toluene, Ethylbenzene, Xylenes) in soils and groundwater exceeded the international standards. The remediation proposal was designed using kinetic models from the modified Monod equation for two coupled bioreactors, used as a design variable for the Chemical Oxygen Demand (COD). For soil treatment, the sequence was formed by a Soil-Slurry Sequencing Batch Reactor (SS-SBR) and an Upflow Anaerobic Filter separately in three phases (UAF-3SS), operating for 80% and 99% of COD removal, respectively. For groundwater treatment, it was set that the SBR-UAF-3SS sequence performs a COD removal of 60% and 99%, respectively.

Fluorescence-estimated oil concentration (Foil) in the Deepwater Horizon subsea oil plume

Tracking the subsea oil plume during the 2010 Deepwater Horizon Oil Spill (DWH) was conducted using in situ fluorescence via vertical profilers (n = 1157) and discrete sample chemical analyses (n = 7665). During monitoring efforts, discrete samples provided a coarse picture of the oil plume footprint, but the majority of the samples were below standard analytical detection limits for petroleum hydrocarbons. In situ fluorescence data improved the spatial and temporal resolution of the subsea oil plume characterization. Here we synthesized millions of continuous fluorescence data points from hundreds of contemporaneously discrete samples collected to demonstrate how fluorescence could serve as a proxy for Benzene-Toluene-Ethylbenzene-Xylene (BTEX) concentration. Data mined from Gulf Science Data repository were well correlated, and geographically and temporally aligned to provide direct comparisons. Described here are the methods used to calibrate the fluorescence data and to spatially approximate the three-dimensional geographic extent of the oil plume.

Fabrication of C-Doped TiO&lt;sub&gt;2&lt;/sub&gt; Nanosphere for BTEX Degradation of Paint Thinners with Visible Light Irradiation

Carbon (C)-doped TiO2 nanospheres were produced using a solvothermal method, and then characterised with transmission electron microscopy, powder X-ray diffraction pattern and X-ray photoelectron spectroscopy. The C was doped into the TiO2 nanosphere as planned, and the photocatalytic oxidations were studied in environmental chambers under simulative conditions. C-doped TiO2 nanospheres' photocatalytic performance was evaluated by removing benzene, toluene, ethylbenzene, xylenes (BTEX) of paint thinners via the illumination of visible light. A degradation ratio of 93.4% in 90 min exhibited high photocatalytic activity.

Xenobiotic Organic Compounds in a Landfill Leachate

Landfilling is a predominant method of waste disposal in most of the countries. Amongst the disadvantages of landfills use is the generation of gas and leachate which can possibly lead to the contamination of groundwater. Thus, examining of hazardous constituents of leachate such as xenobiotic organic compounds (XOCs) is essential to contain any unwanted impacts on the environment. In this study, leachate samples were collected from Al Amirat un engineered landfill in Muscat in order to examine the presence of XOCs. The results have showed the presence of some kinds of polychlorinated biphenyls (PCBs), pesticides, BTEX (benzene, toluene, ethyl benzene, xylene) and phthalates in low quantities. The concentrations of XOCs were only a small fraction of the total carbon content of leachate, but environmentally relevant leachate pollution levels were estimated to persist for decades to centuries. Thus, leachate should be collected regularly by means of newly constructed boreholes to avoid any risk to the environment. Such old un engineered landfills need to be well capped and rehabilitated to minimize their impacts on the environment.

Integrated on-site collection and off-site analysis of airborne molecular contamination in cleanrooms for integrated circuit manufacturing processes

Both long-term on-site collection and off-site analysis methods were conducted to investigate airborne molecular contaminants (AMCs) in a semiconductor wafer cleanroom. The removal efficiency of SO2 and NO2 for chemical filters on a make-up air unit (MAU) in the cleanroom is approximately 50%, though this value does not meet the removal efficiency mentioned in the GB 36306 standard. The removal efficiencies of SO2, H2S, NO, NO2, NH3, and TVOC were approximately 76.5%, 50.9%, 83.5%, 99.3%, 94.8%, and 97.1% after the fan filter unit (FFU) was equipped with a chemical filter. AMCs mainly include benzene, toluene, ethylbenzene, xylene (BTEX), alkanes and alkenes, though BTEX accounts for 77% of the total. VOC concentrations in cleanrooms fitted with FFU chemical filters and where the process equipment was not in operation were found to be lower than those at domestic residences and slightly higher than those found in commercial aircraft cabin air. The daily average TVOC concentrations were negatively correlated with temperature (R2 = 0.46, p < 0.01) and positively correlated with humidity (R2 = 0.26, p < 0.01). The daily average NH3 concentrations were negatively correlated with T (R2 = 0.19, p < 0.05) and positively correlated with RH (R2 = 0.18, p < 0.01). Dibutyl phthalate (DBP) and dioctyl phthalate/diethylhexyl phthalate (DOP/DEHP) were detected in the new sealing joint strips in the HEPA filters. Phthalates and organophosphates were not detected in the new filter papers.

Investigation of the Presence Volatile Organic Compounds (BTEX) in the Ambient Air and Biogases Produced by a Shiraz Landfill in Southern Iran

The generation and emission of volatile organic compounds (VOCs) affects the environment and air quality, playing an important role in global warming, depletion of atmospheric ozone and emission of unpleasant odors, but also directly affect human health. This study investigated the health risks of benzene, toluene, ethylbenzene, xylene (BTEX) compounds and biogas released in and around the municipal landfill. Sampling of the VOCs was carried out by the 1501NIOSH method from 8 points over 5 months. The samples were analyzed for BTEX in the ambient air of the landfill, resulting in 0.03–18.09 ppm concentrations, while for biogases a 0.08–25.2 ppm range was found. Assessment of definite health and potential risks showed that the lifetime cancer risk (LCR) for benzene and hazard quotient (HQ) for the BTEX components in all studied sampling sites are higher than the acceptable standard. The high concentration of benzene measured in ambient air indicated that petroleum compounds containing benzene and its derivatives have the highest value in the category of BTEX compounds among all emissions. Therefore, high concentrations of volatile compounds derived from VOCs, especially benzene, should be reduced at the site with control engineering measures.

Biodegradation of p-xylene-a comparison of three psychrophilic Pseudomonas strains through the lens of gene expression.

p-Xylene is considered a recalcitrant compound despite showing a similar aromatic structure to other BTEXs (benzene, toluene, ethylbenzene, xylene isomers). This study evaluated the p-xylene biodegradation potential of three psychrophilic Pseudomonas strains (Pseudomonas putida S2TR-01, Pseudomonas synxantha S2TR-20, and Pseudomonas azotoformans S2TR-09). The p-xylene metabolism-related catabolic genes (xylM, xylA, and xylE) and the corresponding regulatory genes (xylR and xylS) of the selected strains were investigated. The biodegradation results showed that the P. azotoformans S2TR-09 strain was the only strain that was able to degrade 200mg/L p-xylene after 60h at 15°C. The gene expression study indicated that the xylE (encoding catechol 2,3-dioxygenase) gene represents the bottleneck in p-xylene biodegradation. A lack of xylE expression leads to the accumulation of intermediates and the inhibition of biomass production and complete carbon recovery. The activity of xylene monooxygenase and catechol 2,3-dioxygenase was significantly increased in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg, respectively) in the presence of p-xylene. The expression of the ring cleavage enzyme and its encoding gene (xylE) and activator (xylS) explained the differences in the p-xylene metabolism of the isolated bacteria and can be used as a novel biomarker of efficient p-xylene biodegradation at contaminated sites.

BTEX and formaldehyde levels at a suburban site of Agra: Temporal variation, ozone formation potential and health risk assessment

Benzene, Toluene, Ethyl-Benzene, Xylene (BTEX) and Formaldehyde (HCHO) are volatile organic compounds (VOCs) having adverse effects on air quality and on human health. Limited studies reporting BTEX and Formaldehyde concentrations and assessing their human health risk are available for India. The present study investigates the BTEX and HCHO concentrations and their carcinogenic and non-carcinogenic risk to humans at a suburban site of Agra during January 2017–December 2019. The average concentration of ΣBTEX was 80.2 ± 20.8 μg/m 3 ranging from 37.9 to 151.8 μg/m3 with Benzene concentration exceeding National Ambient Air Quality Standards (NAAQS) annual limit. Diurnal pattern of BTEX showed morning and evening peaks while Formaldehyde showed higher concentrations during afternoon. Higher concentrations of BTEX were observed during the winter season however, Formaldehyde showed higher concentrations during summer season. B/T ratio suggested vehicular emission may be the primary source of VOCs at the study site. Among BTEX, Toluene showed maximum ozone forming potential (OFP). The cancer risks for Benzene and Formaldehyde were higher than 1 × 10−6 (more than the acceptable value). Hazard index for BTEX were within acceptable limit while for Formaldehyde health quotient was 1.

Volatile organic compounds (VOCs) in indoor air and tap water samples in residences of pregnant women living in an area of unconventional natural gas operations: Findings from the EXPERIVA study

BackgroundNortheastern British Columbia (Canada) is an area of unconventional natural gas (UNG) exploitation by hydraulic fracturing, which can release several contaminants, including volatile organic compounds (VOCs). To evaluate gestational exposure to contaminants in this region, we undertook the Exposures in the Peace River Valley (EXPERIVA) study. ObjectivesWe aimed to: 1) measure VOCs in residential indoor air and tap water from EXPERIVA participants; 2) compare concentrations with those in the general population and explore differences related to sociodemographic and housing characteristics; and 3) determine associations between VOC concentrations and density/proximity to UNG wells. MethodsEighty-five pregnant women participated. Passive air samplers were analyzed for 47 VOCs, and tap water samples were analyzed for 44 VOCs. VOC concentrations were compared with those from the Canadian Health Measure Survey (CHMS). We assessed the association between different metrics of well density/proximity and indoor air and tap water VOC concentrations using multiple linear regression. Results40 VOCs were detected in >50% of air samples, whereas only 4 VOCs were detected in >50% of water samples. We observed indoor air concentrations >95th percentile of CHMS in 10–60% of samples for several compounds (acetone, 2-methyl-2-propanol, chloroform, 1,4-dioxane, hexanal, m/p-xylene, o-xylene, styrene, decamethylcyclopentasiloxane, dodecane and decanal). Indoor air levels of chloroform and tap water levels of total trihalomethanes were higher in Indigenous participants compared to non-Indigenous participants. Indoor air levels of chloroform and acetone, and tap water levels of total trihalomethanes were positively associated with UNG wells density/proximity metrics. Indoor air BTEX (benzene, toluene, ethylbenzene, xylenes) levels were positively correlated with some well density/proximity metrics. ConclusionOur results suggest higher exposure to certain VOCs in pregnant women living in an area of intense unconventional natural gas exploitation compared with the general Canadian population, and that well density/proximity is associated with increased exposure to certain VOCs.

Diffusive uptake rates for passive air sampling: Application to volatile organic compound exposure during FIREX-AQ campaign

Passive (diffusive) sampling using sorbents is an economical and versatile method of measuring pollutants in air, including volatile organic compounds (VOCs). Diffusive uptake rates (UTRs) are needed for each analyte to obtain average concentrations during a specific passive sampling time duration. Here, a simultaneous active/diffusive ambient air sampling technique on Tenax®TA was employed to measure 24-hours, 7, 14 and 28-days UTRs of up to 27 VOCs, including benzene, toluene, ethylbenzene, xylenes (BTEX), C6–C12 hydrocarbons, benzenes derivatives, tetrachloroethylene, pinenes and limonene. Samples were analyzed via thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for desired analytes. Seven-day UTR values ranged from 0.17 to 0.59 mL/min and many compounds exhibited a linear relationship with UTR and time duration up to 14 or 28 days. This may be the most comprehensive UTR tabulation of VOCs on Tenax®TA for time periods of 24 hours –28 days available. These rates were applied to VOC data measured during the 2019 NASA/NOAA Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign, with goals to determine the chemical composition of western US wildfire smoke and to assess human exposure to air toxics. Summer 2019 exposure levels of BTEX at five Northwestern cities were low and the cancer risk due to benzene was assessed during FIREX-AQ to be background or 1 × 10−6. The UTRs derived here can be useful in applications of diffusive sampling, including estimation of sub-chronic to chronic human exposure risk of air toxics and wildfire smoke.

Lethal and sublethal effects of diluted bitumen and conventional oil on fathead minnow (Pimephales promelas) larvae exposed during their early development.

The increasing extraction of bitumen from the oil sands region in Canada is creating a need for transport. Spills from current and projected pipelines represent a significant environmental risk, especially for freshwater ecosystems. The toxicity of diluted bitumen (dilbit) on freshwater fish is largely unknown. This study assessed the toxicity of two dilbits (Clearwater McMurray and Bluesky) and compared their toxicity to a conventional oil (Lloydminster Heavy) on fathead minnow (Pimephales promelas) larvae. Larvae were exposed to various concentrations of the water-accommodated fraction (WAF) of the oils during 7 days from hatching. In the WAF treatments, the concentrations of volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, xylene (BTEX), hydrocarbons containing 6 to 10 carbon atoms (C6-10), and polycyclic aromatic hydrocarbons (PAHs) and their alkylated forms were measured. Both dilbits contained higher concentrations of light components, while the conventional oil contained the highest concentrations of PAHs and alkylated PAHs. The Clearwater McMurray dilbit induced a higher mortality, with a maximum of 65.3%, while the other oils induced a similar mortality up to 16.5% and 18.6% for Lloydminster and for Bluesky, respectively. All three oils induced an increase in gene expression of the phase I detoxification enzyme (cyp1a) with increasing total hydrocarbon concentrations. All three exposures induced a similar increase in glutathione S-transferase (GST) activity, but no change in gst gene expression. For the Bluesky and Lloydminster exposures, an increase in malondialdehyde concentration was also observed, suggesting a rate limiting capacity of GST and phase II enzymes to perform the biotransformation of the PAH metabolites. Overall, this study brings new insights on the toxicity of dilbits in comparison to conventional oils on early life stages of North American freshwater fish and demonstrated that dilbits can be more toxic than conventional oils, depending on their composition and diluent proportions.

Pyrolytic oil with aromatic-rich hydrocarbons via microwave-induced in-situ catalytic co-pyrolysis of empty fruit bunches with a waste truck tire

Microwave-induced in-situ catalytic co-pyrolysis of empty fruit bunch (EFB) with truck tire (TT) using a low-cost heterogeneous catalyst to produce aromatic-rich pyrolytic oil is proposed. In this study, the effect of catalyst type and catalyst-to-feedstock ratio were investigated. Three types of catalysts were used, namely activated carbon (AC), clay (CL) and calcium oxide (CaO), while the catalyst-to-feedstock ratios of 1:5, 2:5, 3:5 were investigated. Although the catalytic co-pyrolysis significantly reduced the yield, high monoaromatic hydrocarbon fraction and BTEX (benzene, toluene, ethylbenzene, xylene) selectivity were observed in the pyrolytic oil. The study showed that the AC-to-feedstock ratio of 2:5 (AC-0.4) contained a high fraction of monoaromatic hydrocarbon (54.32%) with high selectivity of BTEX (30.42%). The elemental analysis also found the AC catalyst produced hydrogen-rich pyrolytic oil with lower undesirable compounds, mainly from oxygenates (ketone group), nitrogen and sulphur compounds. Moreover, the catalytic co-pyrolysis using AC reduces pyrolytic oil's pH value from 4.7 (un-Cat) to pH 5.02 (AC-0.4). However, the AC catalyst had little effect in increasing the higher heating value (HHV) of pyrolytic oil from 42.29 (un-Cat) to 42.47 MJkg−1 (AC-0.4) with a slightly decreased energy recovery from 62.0% (un-Cat) to 56.5% (AC-0.4). The residual gas analysis determined that the dominant gaseous produced from catalytic cracking using AC were CO2 and CH4. A reaction mechanism between the volatiles of EFB and TT is proposed. Overall, the study has successfully demonstrated an approach for producing pyrolytic oil with high monoaromatic fraction and high selectivity of BTEX from in-situ catalytic co-pyrolysis of EFB with TT using low-cost heterogeneous catalyst.

Impact of Industrial Atmospheric Emissions on Ambient Air Quality in Arzew Area, Oran State, Algeria

This work focuses on identifying the source of BTEX (Benzene, Toluene, Ethylbenzene, Xylene) emissions generated by hydrocarbon-related industrial activities and evaluation of its impact on ambient air quality according to European Union (EU) regulations during 2019. The spatial distribution of BTEX concentrations suggest that massive emissions are mainly due to the oil refining activity. BTEX concentration levels at the sampling sites show that benzene was more dominant. Considering the level of atmospheric pollution relative to the indicative value (2µg/m3) recommended by the EU, the ambient air is considered to be quite polluted with benzene content (5.36 µg/m3) produced mainly by emissions from the oil refining industrial complex.

Exposure to BTEX concentration and the related health risk assessment in printing and copying centers.

This study was derived to investigation of BTEX (benzene, toluene, ethylbenzene, xylenes) concentrations in printing and copying centers (PCCs) in Ardabil city of Iran. Fifty-three PCCs were randomly selected from all the 136 number of PCCs and BTEX was sampled form their indoor air. The results showed that the concentration of BTEX in the indoor air PCCs is lower than the OELs (occupational exposure limit) in all cases. The obtained mean concentrations of benzene, toluene, ethylbenzene, and xylene were 93.6±63.2, 150.6±99.2, 34.3±16.8, and 29.5±15.2 μg/m3 respectively. Type of printer, number of printing and copying device, and type of ventilation system had significant influence on the BTEX concentration. The mean inhalation lifetime cancer risk (LTCR) value for benzene and ethylbenzene in the indoor air of the PCCs with LaserJet and inkjet printers was 44.4 × 10-6 and 153.3 × 10-6, and 23.4×10-6 and 54.2× 10-6, respectively, which were higher than EPA (Environmental Protection Agency) and World Health Organization (WHO) recommended limits. The hazard quotient (HQ) of benzene in the indoor air of the PCCs with inkjet printers was >1, which indicates that the non-carcinogenic risks associated with exposure to these compounds are considerable.

Exposures and health impact for bicycle and electric scooter commuters in Taipei

Bicycle and scooter commuters are known to expose to more traffic-related pollutants. Benzene, toluene, ethylbenzene, xylenes (BTEXs), and PM2.5 were measured along four routes during rush hour and non-rush hour periods by cyclists and motorcyclists in Taipei, Taiwan. The health impacts were also evaluated using health impact modeling (HIM) approach. The average exposures of total BTEX and PM2.5 were 20.07 ppb and 23.27 μg/m3 for the cyclists and 33.96 ppb and 27.65 μg/m3 for the motorcyclists, respectively. Riding on an “alternative” route resulted in lower exposure. Scooters could contribute more to PM2.5 exposure than buses/trucks and passenger cars. Cyclists could have a lower risk of all-cause mortality and a single-pollutant HIM was found to result in underestimations. In conclusion, the number of scooters in traffic should be reduced, and commuters should be encouraged to shift from gasoline scooters to bicycles to reduce air pollution.

Contaminant Diffusion through a Novel Coextruded Vapor Barrier

AbstractOrganic contaminant diffusion through a novel multilayer coextruded vapor barrier is examined for benzene, toluene, ethylbenzene, xylenes (BTEX), trichloroethylene (TCE), and tetrachloroeth...