Airborne Benzene Research Articles

Synergy of Lithium, Cobalt, and Oxygen Vacancies in Lithium Cobalt Oxide for Airborne Benzene Oxidation: A Concept of Reusing Electronic Wastes for Air Pollutant Removal

In this study, a recovery strategy of turning cathode materials of waste lithium-ion batteries, lithium cobalt oxide (LiCoO2), into high-performance catalysts for the oxidation of airborne benzene is investigated. Part of the Co3+ in LiCoO2 was leached out from the [CoO6] octahedra by HNO3 solution via the disproportion reaction with the deintercalation of interlayer Li+ ions, resulting in the formations of Li, Co, and O vacancies. The presence of Li and O vacancies facilitated gaseous benzene adsorption and subsequent activation of adsorbed benzene, and the Co vacancies together with the oxygen vacancies induced the generation of plenty of active surface oxygen species, accordingly the catalytic activity of the acid-modified LiCoO2 was greatly improved with good resistance to the alternative “heating-cooling” operation and stability from 0.8 to 2.3 vol % of humidity. More importantly, the acid modification process is green since the HNO3 solution could be reused many times to produce effective catalysts,...

Determinants of airborne benzene evaporating from fresh crude oils released into seawater

Benzene, toluene, ethylbenzene, xylenes, naphthalene and n-hexane evaporating from a thin oil film was measured for 30 min in a small-scale test system at 2 and 13 °C and the impact of physicochemical properties on airborne benzene with time after bulk oil release was studied. Linear mixed-effects models for airborne benzene in three time periods; first 5, first 15 and last 15 min of sampling, indicated that benzene content in fresh oil, oil group (condensate/light crude oil) and pour point were significant determinants explaining 63–73% of the total variance in the outcome variables. Oils with a high pour point evaporated considerably slower than oils with a low pour point. The mean air concentration of total volatile organic compounds was significatly higher at 13 °C (735 ppm) compared to 2 °C (386 ppm) immediately after release of oil, but at both temperatures the concentration rapidly declined.

Facile and green synthetic strategy of birnessite-type MnO2 with high efficiency for airborne benzene removal at low temperatures

Volatile organic compounds (VOCs) are notorious for global air pollution. It is key to find a material with high and stable activity to catalytically oxidize VOCs at low temperatures. In this paper, benzene, as a typical VOC contaminant, could be completely oxidized on a highly efficient and moisture-resistant birnessite MnO2 at temperatures significantly lower than the reported values in literature. The best catalyst (H-MnO2 (30-0.2-6)) could be tailored via a facile and green process by engineering a proper combination of treatment temperature (30 °C), HNO3 aqueous concentration (0.2 M) and treatment period (6 h). The thus-obtained MnO2 exhibited a stable removal efficiency of ˜94% for 318 ppm of benzene under a high space velocity of 120 L·g−1 h−1 and 1.5 vol.% H2O at 250 °C. XRD, SEM, (HR)TEM, EDS mapping, XPS, H2-TPR, O2-TPD and pyridine adsorption IR were combined with the deliberately designed C6H6-TPD, surface oxidation reaction of benzene and CO2-TPD to disclose the tremendous role of acid treatment in benzene oxidation. The increased acid sites and acidity of the acid-treated surface promoted the adsorption and activation of gaseous benzene, and the lattice oxygen and surface adsorbed oxygen became more facile and reactive due to the generated active oxygen vacancies via acid treatment, these two favorable factors together with the easy desorption of reaction products resulting in the excellent performance of the acid-treated sample. Finally, the acid treatment method can be extended to most of other crystal structures of manganese dioxides except α-MnO2.

Effect of Benzene Exposure on the Urinary Biomarkers of Nucleic Acid Oxidation in Two Cohorts of Gasoline Pump Attendants.

(1) Background: The oxidized guanine derivatives excreted into urine, products of DNA and RNA oxidation and repair, are used as biomarkers of oxidative damage in humans. This study aims to evaluate oxidative damage in gasoline pump attendants occupationally exposed to benzene. Benzene is contained in the gasoline but it is also produced from traffic and from smoking. (2) Methods: Twenty-nine gasoline pump attendants from two major cities of Saudi Arabia and 102 from Italy were studied for urinary 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo), 8-oxo-7,8-dihydroguanosine (8-oxoGuo), and S-phenyl-mercapturic acid (SPMA) for benzene exposure and urinary cotinine for smoking status assessment by liquid chromatography-tandem mass spectrometry. Airborne benzene was also assessed in the Italian group by gas-chromatography with flame ionization detector (GC-FID). (3) Results: The results suggest that high levels of benzene exposure can cause an accumulation of SPMA and bring about the formation of the oxidation biomarkers studied to saturation. At low exposure levels, SPMA and oxidation biomarker levels were correlated among them and were associated with the smoking habit. (4) Conclusions: The study confirms the association between benzene exposure and the excretion of nucleic acid oxidation biomarkers and enhances the importance of measuring the smoking habit, as it can significantly influence oxidative damage, especially when the exposure levels are low.

Urinary and air biomonitoring of occupational exposure to benzene in oil pit workers

The purpose of this study is to evaluate the personal exposure to benzene and its relationship with biomonitoring and quantitative risk assessment among the personnel working and living near oil pits. This study was conducted in one of oil subsidiary companies in Kharg in 2017. Airborne benzene exposure was evaluated over 8-h periods during work-shift by using personal active samplers. Urinary O-Cresol levels were determined using GC-FID for separation and detection. The highest mean concentration of airborne benzene was at monitoring location, A (0.53 ppm), monitoring location H (0.59 ppm) in the spring, monitoring location M (0.72 ppm) and monitoring location P (0.8 ppm) in the summer, which was more than suggested by the American Conference of Governmental Industrial Hygienists. No direct linear relationship was found between the concentration of airborne benzene, age, work experience, urinary creatinine, and O-Cresol in this study (p > .05). No significant difference was observed between urinary O-Cresol and benzene in occupational groups and different seasons (p > .05). The highest mean quantitative risk of cancers was observed in summer (1.21 ± 0.47). According to the results of this study, urinary biomarker O-Cresol is not a suitable measure for evaluating exposure to environmental benzene.

The potential of biochar as sorptive media for removal of hazardous benzene in air

Airborne benzene is hazardous even at sub-ppm levels. Therefore, an effective strategy is required for its removal, such as the use of a sorbent with large adsorption capacity or high breakthrough volume. To meet the goal, the performance for the removal of benzene was assessed by loading benzene at 5 Pa inlet partial pressure against seven types of biowaste-derived biochar: (1) paper mill sludge, (2) conventional biochar with magnetic properties, (3) biochar composites with carbon nanotubes (CNTs), (4) gasification biochar from mixed feedstock, (5) gasification biochar from a single feedstock, (6) modified gasification biochar, and (7) activated carbon (AC) as a reference. The 298 K maximum adsorption capacities (mg g−1), when measured at a benzene inlet pressure of 5 Pa (or 50 ppm in ultrapure nitrogen) and flow rate of 50 mL atm min−1, varied widely for different biochars, from 0.35 (MS: Swine manure + plastic mulch film waste) to 144 mg g−1 (XC-1: biochar from mixed feedstock); their 10% breakthrough volumes (BTV) were in the range of 0.22–492 L g−1, respectively. The experimental data (capacity vs. benzene outlet partial pressure) could be fitted to either two or three linearized Langmuir isotherms with distinctive sorption mechanisms ((1) a retrograde region (Type III isotherm: 0 to ∼0.2 Pa), (2) an intermediate pressure region (0.2 and 2.0 Pa), and (3) a higher pressure region (>2 Pa)) which was also confirmed similarly by Freundlich, Dubinin–Radushkevich, and Elovich fitting. About 65% of the maximum capacity was achieved in the retrograde region. The strongest biochar sorbent, XC-1, showed similar performance as activated carbon to prove its feasibility toward air quality management (AQM) applications.

Different behaviors of birnessite-type MnO2 modified by Ce and Mo for removing carcinogenic airborne benzene

Abstract In this study, Mo6+ and Ce3+, which are the typical high- and low-valence modifiers, were comparatively used as structural and catalytic promoters for birnessite-type MnO2 to remove gaseous benzene. Various characterizations were performed to elaborate how the surface properties of the nanomaterials led to the observed catalytic behaviors. The Mo species existed as highly dispersed MoO3 over the Mo MnO2 while Ce was incorporated into the MnO2 lattice. The activities of the lattice oxygen and oxygen vacancies over the Mo MnO2 were comparable to those of the pristine MnO2, thus resulting in similar catalytic performance. However, the replacement of lattice Mn by Ce inhibited the regular growth of the birnessite crystals and caused distortion of MnO2 lattice. Thanks to the high activity of the lattice oxygen, oxygen vacancies and surface adsorbed oxygen, benzene decomposition was significantly improved over the Ce MnO2. Ce MnO2(0.8) with a nominal Ce/Mn atomic ratio of 0.8 exhibited stable conversion of ∼90% for 395 ppm of benzene in dry gas under 120 L g−1 h−1 of space velocity and 350 °C. Moreover, under similar reaction conditions, the Ce MnO2(0.8) could also stand up water vapor and kept a moderate activity of 60% with 50% of relative humidity.

Chlorophytum comosum–bacteria interactions for airborne benzene remediation: Effect of native endophytic Enterobacter sp. EN2 inoculation and blue-red LED light

This study was performed to determine the effect of plant–endophytic Enterobacter sp. EN2 interactions and blue-red LED light conditions on gaseous benzene removal by plants. It was found that under consecutive benzene fumigation for three cycles (18 days), inoculation of the strain EN2 into sterilized and non-sterilized native C. comosum resulted in significantly increased gaseous benzene removal compared to that in non-inoculated groups under the same light conditions (P < 0.05). Remarkably, EN2 colonization in inoculated plants under LED conditions was higher than under fluorescence conditions as the EN2 could grow better under LED conditions. Strain EN2 possesses NADPH that is used to facilitate benzene degradation and modulate plant growth under benzene stress by bacterial IAA production and ACC deaminase activity; higher IAA and lower ethylene levels were found in inoculated plants compared to non-inoculated ones. These contributed to better benzene removal efficiency. Interestingly, under fumigation for 16 cycles (67 days), there was no difference in gaseous benzene removal between inoculated plants and non-inoculated plants under the same light conditions at initial benzene concentrations of 5 ppm. This is probably due to EN2 reaching maximum growth under all treatments. However, C. comosum exhibited better benzene removal under LED conditions than under fluorescence conditions during 16 cycles, possibly due to better photosynthetic performance and plant growth, leading to more NADPH, and eventually enhanced benzene removal efficiency. Hence, the most efficient acceleration of benzene removal was provided by inoculation of strain EN2 onto C. comosum under blue-red LED light conditions.

Effect of Individual/Co-culture of Native Phyllosphere Organisms to Enhance Dracaena sanderiana for Benzene Phytoremediation

Benzene-tolerant phyllosphere microorganisms isolated from Dracaena sanderiana were identified as Pantoea sp. B11 and Staphylococcus sp. B12. Inoculating D. sanderiana with these microorganisms growing under 70 and 348 mg/m3 of airborne benzene showed a higher benzene removal efficiency than D. sanderiana without inoculation. Under 348 mg/m3 of benzene, inoculating D. sanderiana with Staphylococcus sp. B12 can remove benzene higher than inoculating D. sanderiana with Pantoea sp. B11 and co-culture between Staphylococcus sp. B12 and Pantoea sp. B11. In addition, individual Staphylococcus sp. B12 had higher ability to bio-remediate benzene than individual Pantoea sp. B11 and co-culture. Staphylococcus sp. B12 can also produce high indole-3-acetic acid (IAA) and harbor 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, which can protect plant from the stress. Photosystem II activity and chlorophyll content of D. sanderiana were decreased clearly under exposure with a 348 mg/m3 of benzene. Inoculating D. sanderiana with Staphylococcus sp. B12 had significantly higher photosystem II activity and chlorophyll content than inoculating D. sanderiana with Pantoea sp. B11 and co-cultures. In co-culture inoculation, Pantoea sp. B11 inhibited growth of Staphylococcus sp. B12, which can probably decrease benzene removal efficiency. Application of Staphylococcus sp. B12 can enhance benzene phytoremediation efficiency in D. sanderiana and protect plant from benzene stress.

Biological monitoring of exposure to low concentrations of benzene in workers at a metallurgical coke production plant: new insights into S-phenylmercapturic acid and urinary benzene

Context: Urinary S-phenylmercapturic acid (SPMA) and benzene (U-Ben) are usually measured at the end of the work shift (ES), although their kinetic of elimination is not clearly known.Objective: To investigate SPMA and U-Ben elimination 16 h after the ES, in 93 coke production workers exposed to low benzene concentrations.Materials and methods: Airborne benzene (A-Ben) was measured by passive samplings, while SPMA, U-Ben, methyl-tert-butyl ether (U-MTBE), cotinine (U-Cot) and creatinine were determined on urine samples collected at ES and before the beginning of the next work shift (next BS).Results: Median A-Ben concentrations were 17.2 µg/m3 in the personal and 34.7 µg/m3 in the stationary samplings. SPMA was always detectable, whereas U-Ben was below the limit of quantification in 26.7% of the ES and 35.6% of the next BS samples, and U-MTBE in more than the 80.0% of the samples. At both the sampling times, SPMA and U-Ben showed a positive dependence on personal A-Ben, as well as on creatinine and U-Cot values.Discussion and conclusion: SPMA and U-Ben at the next BS were dependent on the exposure to low benzene concentrations suffered in the previous work shift, prompting a reconsideration of the urine sampling time recommended by the American Conference Governmental Industrial Hygienists (ACGIH).

Trends of BTEX in the central urban area of Iran: A preliminary study of photochemical ozone pollution and health risk assessment

The Environmental Protection Agency (USEPA) has identified Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) as hazardous air pollutants. In this study, BTEX sampling was conducted at 20 sites during summer 2015 and winter 2016 in Yazd. Concentrations of BTEX were analyzed using a gas chromatograph with a flame ionization detector (GC-FID). In addition, ozone formation potential (OFP) and the health risks of BTEX were calculated. Spatial mapping was accomplished using the Kriging method. The obtained concentrations of total BTEX ranged from 8 to 560 μg/m3. The highest average individual values belonged to toluene and xylene (38 ± 42 and 41 ± 45 μg/m3, respectively). Seasonal variation showed a downward trend from summer to winter. The peak BTEX emissions occurred in the evenings, due to rush hour traffic and meteorological factors. Spatial analysis showed that the maximum levels of BTEX occurred on high traffic roads or near fuel stations. Significant correlation coefficients between benzene and other BTEX compounds revealed that BTEX were emitted from main sources including gasoline vehicles and stations. The mean ratio of toluene/benzene (T/B) in summer (1.8) was more than winter (1.4). The seasonal changes in T/B ratio possibly were attributed to photochemistry, meteorology, and emission aspects. The OFP values were 720 ± 729 and 375 ± 319 μg/m3 in summer and winter, respectively. OFPs, ranked maximum to minimum, were as follows: xylene > toluene > ethylbenzene > benzene. Although the values of the non-cancer risk of BTEX were under permissible recommended level, a cancer risk still exists because of high values of airborne benzene.

Effect of exogenous methyl jasmonate on airborne benzene removal by Zamioculcas zamiifolia: The role of cytochrome P450 expression, salicylic acid, IAA, ROS and antioxidant activity

The exogenous application of methyl jasmonate (MeJA) has emerged as a promising approach for enhancing plant stress resistance. However, little is known about the effect of exogenous MeJA for promoting airborne benzene removal by plants. Here, we elucidated the effect of various MeJA concentrations on Zamioculcas zamiifolia stress response in relation to antioxidant enzyme activity, indole-3-acetic acid (IAA) contents, reactive oxygen species (ROS) accumulation and the expression levels of cytochrome P450 monooxygenase gene responsible for benzene hydroxylation. Exogenous MeJA at low physiological levels (10, 30 and 50μM) enhanced plant resistance to benzene stress through triggering the activities of antioxidant enzymes, enhancing IAA levels and lowering ROS accumulation. Moreover, MeJA at 10, 30 and 50μM induced the expression levels of P450. Higher expression levels of P450 could indirectly enhance benzene removal ability of the plants. Interestingly, the upregulated P450 trends were consistent with the increasing IAA contents and MeJA concentrations. However, MeJA at high concentrations (100μM) declined gaseous benzene removal due to limited antioxidant activity, low IAA contents and high ROS accumulation as well as closed stomata. Moreover, under 100μM MeJA treatment, high levels of ROS and salicylic acid downregulated the expression levels of P450. Our results provide comprehensive evidence with regard to the exogenous application of MeJA for promoting plant stress resistance and enhancing airborne benzene phytoremediation.

MiR-34a, a promising novel biomarker for benzene toxicity, is involved in cell apoptosis triggered by 1,4-benzoquinone through targeting Bcl-2

Exposure to benzene is inevitable, and concerns regarding the adverse health effects of benzene have been raised. Most investigators found that benzene exposure induced hematotoxicity. In this regard, Our study aimed to explore a novel potential biomarker of adverse health effects following benzene exposure and the toxic mechanisms of benzene metabolites in vitro. This study consisted of 314 benzene-exposed workers and 288 control workers, an air benzene concentration of who were 2.64 ± 1.60 mg/m3 and 0.05 ± 0.01 mg/m3, respectively. In this population-based study, miR-34a expression was elevated in benzene-exposed workers. The correlation of miR-34a with the airborne benzene concentration, S-phenylmercapturic acid (S-PMA) and trans, trans-muconic acid (t, t-MA), all of which reflect benzene exposure, was found. Correlation analysis indicated that miR-34a was associated with peripheral blood count, alanine transaminase (ALT) and oxidative stress. Furthermore, multivariate analysis demonstrated that miR-34a expression was strongly associated with white blood cell count (structure loadings = 0.952). In population-based study, miR-34a had the largest contribution to altered peripheral blood counts, which reflect benzene-induced hematotoxicity. The role of miR-34a in benzene toxicity was assessed using lentiviral vector transfection. Results revealed that 1,4-benzoquinone induced abnormal cell apoptosis and simultaneously upregulated miR-34a accompanied with decreased Bcl-2. Finally, inhibition of miR-34a elevated Bcl-2 and decreased 1,4-benzoquinone-induced apoptosis. In conclusion, miR-34a was observed to be involved in benzene-induced hematotoxicity by targeting Bcl-2 and could be regarded as a potential novel biomarker for benzene toxicity.

Euphorbia milii-Endophytic Bacteria Interactions Affect Hormonal Levels of the Native Host Differently Under Various Airborne Pollutants.

This study was conducted to assess the effect of plant-native endophytic bacteria interactions on indole-3-acetic acid (IAA), ethylene levels, and hormonal balance of Euphorbia milii under different airborne pollutants. IAA levels and airborne formaldehyde removal by E. milii enhanced when inoculated with endophytic isolates. However, one isolate, designated as root endophyte 4, with the highest levels of IAA production individually, declined gaseous formaldehyde removal of plant, since it disturbed hormonal balance of E. milii, leading to IAA levels higher than physiological concentrations, which stimulated ethylene biosynthesis and stomatal closure under light conditions. However, plant-root endophyte 4 interactions favored airborne benzene removal, since benzene was more phytotoxic and the plant needed more IAA to protect against benzene phytotoxicity. As trimethylamine (TMA) was not toxic, it did not affect plant-endophyte interactions. Therefore, IAA levels of root endophyte 4-inoculated E. milii was not significantly different from a noninoculated one. Under mixed-pollutant stress (formaldehyde, benzene, TMA), root endophyte 4-inoculated E. milii removed benzene at the lowest rate, since benzene was the most phytotoxic pollutant with the greatest molecular mass. However, TMA (with greater molecular mass) was removed faster than formaldehyde due to higher phytotoxicity of formaldehyde. Plant-endophyte interactions were affected differently under various airborne pollutants.

A lack of consensus in the literature findings on the removal of airborne benzene by houseplants: Effect of bacterial enrichment

Removal rates of benzene and formaldehyde gas by houseplants reported by several laboratories varied by several orders of magnitude. We hypothesized that these variations were caused by differential responses of soil microbial populations to the high levels of pollutant used in the studies, and tested responses to benzene by plants and soils separately. Five houseplant species and tobacco were exposed to benzene under hydroponic conditions and the uptake rates compared. Among the test plants, Syngonium podophyllum and Chlorophytum comosum and Epipremnum aureum had the highest benzene removal rates. The effects of benzene addition on populations of soil bacteria were determined using reverse transcription quantitative PCR (RT-qPCR) assays targeting microbial genes involved in benzene degradation. The total bacterial population increased as shown by increases in the levels of eubacteria 16S rRNA, which was significantly higher in the high benzene incubations than in the low benzene incubations. Transcripts (mRNA) of genes encoding phenol monooxygenases, catechol-2,3-dioxygenase and the housekeeping gene rpoB increased in all soils incubated with high benzene concentrations. Therefore the enrichment of soils with benzene gas levels typical of experiments with houseplants in the literature artificially increased the levels of total soil bacterial populations, and especially the levels and activities of benzene-degrading bacteria.

Exposure to BTEX and Ethers in Petrol Station Attendants and Proposal of Biological Exposure Equivalents for Urinary Benzene and MTBE.

To assess exposure to benzene (BEN) and other aromatic compounds (toluene, ethylbenzene, m+p-xylene, o-xylene) (BTEX), methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) in petrol station workers using air sampling and biological monitoring and to propose biological equivalents to occupational limit values. Eighty-nine petrol station workers and 90 control subjects were investigated. Personal exposure to airborne BTEX and ethers was assessed during a mid-week shift; urine samples were collected at the beginning of the work week, prior to and at the end of air sampling. Petrol station workers had median airborne exposures to benzene and MTBE of 59 and 408 µg m(-3), respectively, with urinary benzene (BEN-U) and MTBE (MTBE-U) of 339 and 780 ng l(-1), respectively. Concentrations in petrol station workers were higher than in control subjects. There were significant positive correlations between airborne exposure and the corresponding biological marker, with Pearson's correlation coefficient (r) values of 0.437 and 0.865 for benzene and MTBE, respectively. There was also a strong correlation between airborne benzene and urinary MTBE (r = 0.835). Multiple linear regression analysis showed that the urinary levels of benzene were influenced by personal airborne exposure, urinary creatinine, and tobacco smoking [determination coefficient (R(2)) 0.572], while MTBE-U was influenced only by personal exposure (R(2) = 0.741). BEN-U and MTBE-U are sensitive and specific biomarkers of low occupational exposures. We propose using BEN-U as biomarker of exposure to benzene in nonsmokers and suggest 1457 ng l(-1) in end shift urine samples as biological exposure equivalent to the EU occupational limit value of 1 p.p.m.; for both smokers and nonsmokers, MTBE-U may be proposed as a surrogate biomarker of benzene exposure, with a biological exposure equivalent of 22 µg l(-1) in end shift samples. For MTBE exposure, we suggest the use of MTBE-U with a biological exposure equivalent of 22 µg l(-1) corresponding to the occupational limit value of 50 p.p.m.

Health risk equations and risk assessment of airborne benzene homologues exposure to drivers and passengers in taxi cabins.

Interior air environment and health problems of vehicles have attracted increasing attention, and benzene homologues (BHs) including benzene, toluene, ethylbenzene, xylenes, and styrene are primary hazardous gases in vehicular cabins. The BHs impact on the health of passengers and drivers in 38 taxis is assessed, and health risk equations of in-car BHs to different drivers and passengers are induced. The health risk of in-car BHs for male drivers is the highest among all different receptors and is 1.04, 6.67, and 6.94 times more than ones for female drivers, male passengers, and female passengers, respectively. In-car BHs could not lead to the non-cancer health risk to all passengers and drivers as for the maximal value of non-cancer indices is 0.41 and is less than the unacceptable value (1.00) of non-cancer health risk from USEPA. However, in-car BHs lead to cancer health risk to drivers as for the average value of cancer indices is 1.21E-04 which is 1.21 times more than the unacceptable value (1.00E-04) of cancer health risk from USEPA. Finally, for in-car airborne benzene concentration (X, μg/m(3)) to male drivers, female drivers, male passengers, and female passengers, the cancer health risk equations are Y = 1.48E-06X, Y = 1.42E-06X, Y = 2.22E-07X, and Y = 2.13E-07X, respectively, and the non-cancer health risk equations are Y = 1.70E-03X, Y = 1.63E-03X, Y = 2.55E-04X, and Y = 2.45E-04X, respectively.

Estimating Benzene Exposure Level over Time and by Industry Type through a Review of Literature on Korea.

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980–1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990–1994 period, and to 0.1 ppm (n = 294) in the 1995–1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005–2009 period and 4.5 ppm (n = 3,358) for the 2010–2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

작업환경측정 결과를 활용한 벤젠 노출 매트릭스에 대한 연구

Objectives: The aims of this study were to set up benzene exposure matrices according to industry and process and to assess the risk of those occupational exposure to benzene. Methods: The benzene exposure matrices were assembled depending on industry and process, based on an exposure database provided by KOSHA(the Korean Occupational Safety and Health Agency), which was gathered from a workplace hazards evaluation program in Korea. These exposure matrices were assessed by Hallmark Risk Assessment tool. Results: The benzene was treated 412 industries sector(36%), 2,747 business places, and 471 industrial processes according to database. The arithmetic mean of past decade 8 hours time-weighted average of airborne benzene concentrations in the workplace was 0.10722 ppm. 1.07% of the total sample were greater than OEL, and 59.8% were showed less than the limit of detection. The highest risk values(Danger Value) were seen 36 industries including manufacture of general paints and similar product and 12 processes, such as other painting of manufacture of metal fabricated members. Exposure matrices based on employee exposure data base may provide exposure histories and can be used in epidemiological studies. Conclusions: It was found that more attentions should be paid to 36 among 412 industries and 12 of 471 processes, with a higher risk value.

Investigation of gasoline distributions within petrol stations: spatial and seasonal concentrations, sources, mitigation measures, and occupationally exposed symptoms.

We measured levels of VOCs and determined the distributions of benzene concentrations over the area of two petrol stations in all three seasons. Using the concentrations and sampling positions, we created isoconcentration contour maps. The average concentrations ranged 18-1288 μg m(-3) for benzene and 12-81 μg m(-3) for toluene. The contour maps indicate that high-level contours of benzene were found not only at the fuel dispenser areas but also at the storage tank refilling points, open drainage areas where gasoline-polluted wastewater was flowing, and the auto service center located within the station area. An assessment of the benzene to toluene ratio contour plots implicates that airborne benzene and toluene near the fuel dispenser area were attributed to gasoline evaporation although one of the studied stations may be influenced by other VOC sources besides gasoline evaporation. Additionally, during the routine refilling of the underground fuel storage tanks by a tank truck, the ambient levels of benzene and toluene increased tremendously. The implementation of source control by replacing old dispensers with new fuel dispensers that have an efficient cutoff feature and increased delivery speed can reduce spatial benzene concentrations by 77%. Furthermore, a questionnaire survey among 63 service attendants in ten stations revealed that headache was the most reported health complaint with a response rate of 32%, followed by fatigue with 20%. These prominent symptoms could be related to an exposure to high benzene concentrations.