Airborne Benzene Concentrations Research Articles

Airborne Benzene Concentrations Increase Trans, Trans-Muconic Acid (tt-MA) Levels and Liver Function in Workers in The Manufacturing Industry

The use of benzene as a solvent in the manufacturing industry can be dangerous because it is volatile, toxic, and carcinogenic. Exposure to benzene occurs through inhalation of the chemical in the air, which can enter the human body through the respiratory system. The levels of trans, trans-Muconic Acid (tt-MA), which is used to metabolize benzene, can be affected by the amount of exposure to the chemical. This study aims to determine the differences in exposure to benzene in the air by measuring the tt-MA indicators and liver function of workers in the manufacturing industry. This research uses an observational and cross-sectional approach, with a population of 158 employees from both administration and production units. The sample size for the study is 16 respondents, selected using the consecutive sampling technique. The research instrument uses a questionnaire and examines urine samples using the in-house method. Blood samples are examined using IFCC 37 C. The data is processed using the independent-sample t-test and Pearson correlation. The results show that the level of benzene in the air is below the threshold of 0.5 ppm. However, there is a significant difference in the results of tt-MA and SGOT (p<0.05), while the levels of SGPT (p>0.05) show no significant differences. In conclusion, there are differences in the tt-MA and SGOT exposure levels between workers in the production and toxicity units, while SGPT does not show significant differences. It is recommended that the industry maximizes the use of local exhaust ventilation and prohibits smoking.

Using Urinary Biomarkers to Estimate the Benzene Exposure Levels in Individuals Exposed to Benzene

Urinary benzene metabolites trans, trans-muconic acid (t, t-MA), and S-phenyl mercapturic acid (S-PMA) are often used as biomarkers of internal exposure to benzene. However, there are few reports on using urinary benzene metabolites to estimate airborne benzene concentrations in individuals exposed to benzene. In this study, t, t-MA, and S-PMA were analyzed by UPLC-MS/MS, and a simple pharmacokinetic model was used to calculate the daily intake (DI) of benzene based on the levels of urinary t, t-MA, and S-PMA in occupational individuals. The back-calculated airborne benzene levels (BCABL) were obtained from the DI of benzene. Among the exposed subjects (n = 84), the median BCABL (3.67 mg/m3) based on t, t-MA was very close to the median level of measured airborne benzene (3.27 mg/m3, p = 0.171), and there was no effect of smoking or dietary habits on t, t-MA-based BCABL. In the control subjects (n = 49), the levels of measured airborne benzene were all below the quantitation limit (0.024 mg/m3), and the BCABL (0.002-0.25 mg/m3) calculated by S-PMA was close to this background level. Our study suggests that the t, t-MA-based BCABL can reflect the actual airborne benzene level in a range of 1.10-86.91 mg/m3 and that the S-PMA-based BCABL is more reliable for non-professional benzene exposure.

Oil Spill Fate and Trajectory Simulation for Sierra Leone's Offshore Exploration Basin, Using the Savanah-1X Well as the Focal Point

ABSTRACTThe demand for crude oil and petroleum products have subsequently led to an increase in the likelihood of occurrence of oil spills. It is therefore imperative to understand the impacts of these spills on humans and the environment. Developing appropriate oil spill response and remediation techniques can be achieved by understanding the fate and likely trajectory of different types of oils, once they come in contact with the sea surface. Though still at the nascent stage of oil and gas exploration, the Sierra Leone basin is known to hold large undeveloped hydrocarbon reserves which are being exploited with the aim of contributing to national development. With the availability of oil spill modelling tools, and owing to the fact that environmental conditions vary over time, there is the need to carry out routine studies on the likely behavior of a spill offshore Sierra Leone. This study aims to develop a prediction model that would aid in understanding the fate, trajectory and uncertainties of oil spilled on Sierra Leone waters in the dry, rainy, and harmattan seasons. In order to analyze the trajectory of a spill in the Sierra Leone basin, the GNOME software was used. Furthermore, ADIOS2 was also employed to analyze the weathering processes of the spill. The results obtained from GNOME showed that during the dry and rainy seasons, approximately 15% of oil would be stranded on the shores of Sierra Leone, within three – five days. Owing to the permanently warm water temperatures in the Gulf of Guinea basin, a high percentage of the oil is expected to evaporate and disperse within few days of the spill. The weathering models from ADIOS2 reveal that 34% of oil would be lost to evaporation in the dry season, and 36% and 38% will be lost in the rainy and harmattan seasons respectively. Furthermore, it can be seen that dispersion accounts for 2.5% of oil lost in the dry season, 7.8% during the rainy season and 6.2% in the harmattan period. Within 5-days, ADIOS2 reveals a stable water-in-oil emulsion, leading to an increase in viscosity and density. Airborne benzene concentration is expected to be high on the first day of the spill, but would decrease as the days go by. Based on these results, it is recommended that oil spill response personnel are professionally trained, and equipment must be available to respond to spills in a timely and efficient manner.

An Analysis of the Fate and Trajectory Simulation of Bonny Light Crude From The Dangote Single Point Mooring(SPM) Terminal Off the South Atlantic Ocean, Lagos Nigeria

ABSTRACT Crude oil is predicted to become one of the most detrimental sources of anthropogenic pollution to the marine environment. To meet Nigeria's energy need, Dangote Industries Ltd. was granted licence to build a refinery in the Lekki Free Trade Zone in 2014. There is a significant risk of oil spill from the Single Point Mooring terminal of the refinery as it shares close proximity to the Lekki deep seaport, closeness to the shoreline, sensitive environmental receptors as well as social spots (beaches and resorts). To address this gap, this study aims to design a stochastic model for oil spill prediction for the SPM terminal in order to provide an understanding of the trajectory, fate and uncertainties of spilled oil at different environmental and hydrodynamic conditions. The GNOME software was used to model oil spill trajectory in the SPM terminal while ADIOS2 modelled Bonny light crude weathering characteristics. The best guess solution and the minimum regret analysis shows the possibility of oil beaching on the coastline of Lagos, Edo and Delta State as well as the Gulf of Guinea. The fate simulation for 5 days revealed that evaporation will account for 23% and 27% of oil loss in dry and wet season while dispersion will account for 1.3% and 1.6% in the same time period. Within the same time period, Bonny light crude will form a stable emulsion that will increase the viscosity and density of oil. Also, 66% and 59% of oil was remaining after 5 days, while airborne benzene concentration evaporated in 36 hours and 12 hours in the dry and wet season respectively. The results obtained in this research work suggest that, the window of opportunity need to be utilised by stockpiling equipment and mechanical responders for shoreline clean-up to avoid the oil possibly beaching along the Coastline of Lagos, Edo and Delta state as well as countries on the Gulf of Guinea.

Distribution of the environmental and socioeconomic risk factors on COVID-19 death rate across continental USA: a spatial nonlinear analysis.

The COVID-19 outbreak has become a global pandemic. The spatial variation in the environmental, health, socioeconomic, and demographic risk factors of COVID-19 death rate is not well understood. Global models and local linear models were used to estimate the impact of risk factors of the COVID-19, but these do not account for the nonlinear relationships between the risk factors and the COVID-19 death rate at various geographical locations. We proposed a local nonlinear nonparametric regression model named geographically weighted random forest (GW-RF) to estimate the nonlinear relationship between COVID-19 death rate and 47 risk factors derived from the US Environmental Protection Agency, National Center for Environmental Information, Centers for Disease Control and the US census. The COVID-19 data were employed to a global regression model random forest (RF) and a local model GW-RF. The adjusted R2 of the RF is 0.69. The adjusted R2 of the proposed GW-RF is 0.78. The result of GW-RF showed that the risk factors (i.e. going to work by walking, airborne benzene concentration, householder with a mortgage, unemployment, airborne PM2.5 concentration and per cent of the black or African American) have a high correlation with the spatial distribution of the COVID-19 death rate, and these key factors driven from the GW-RF were mapped, which could provide useful implications for controlling the spread of the COVID-19 pandemic.

A SIMPLE AND SENSITIVE LC-MS/MS METHOD FOR THE DETERMINATION OF S-PHENYLMERCAPTURIC ACID IN HUMAN URINE

Benzene is an important environmental and occupational pollutant, and recognized as human carcinogen. S-phenylmercapturic acid (SPMA) is a highly specific biomarker of exposure to benzene, applied in occupational toxicology to assess low levels of benzene exposure. The objective of this study was to develop and validate a one-step liquid extraction bioanalytical method for the quantification of SPMA in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method was applied to the evaluation of benzene exposure in an occupational setting. The assay was linear from 0.5 to 500 ng mL-1 (r>0.99), accurate (91.4-105.2%) and precise, with CV% between 4.73 and 9.96%. SPMA was stable in urine for 90 days at -20 °C. Airborne benzene concentrations, urinary levels of SPMA and t,t-MA were significantly higher in gas station workers (n=30) in comparison to outdoor workers (n=14) and individuals non-occupationally exposed to benzene (n=34). Benzene airborne levels had higher correlation with urinary SPMA (r=0.532, p<0.001) than with t,t-MA (r=0.338, p=0.04), demonstrating the applicability of this biomarker for monitoring low levels of benzene exposure.

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.

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.

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.

Urinary S-phenylmercapturic Acid as a Key Biomarker for Measuring Occupational Exposure to Low Concentrations of Benzene in Chinese Workers

This study analyzed the level of urinary S-phenylmercapturic acid (U-SPMA) for low benzene exposure in a group of Chinese shoe-making workers. Urinary samples from 55 workers exposed to benzene at levels lower than 10 parts per million (ppm) were collected at postshift. U-SPMA level was determined using high-performance liquid chromatography/mass spectrography (HPLC/MS) method. Good linearity of U-SPMA was observed within the range from 10 to 320 μg/L (r = 0.9994). Concentration of airborne benzene ranged from 0.71 to 32.17 mg/m³, and three segments were divided with different levels of exposure (≤6.0, 6.0 to 10.0, 10 to 32.5 mg/m³), the median U-SPMA concentrations were 49.55, 102.15, and 335.69 μg/g Cr, respectively. A good linear correlation was found between U-SPMA levels and airborne benzene concentrations. The selected method could be applied for detecting other working conditions in China.

An Analysis of Historical Exposures of Pressmen to Airborne Benzene (1938–2006)

Benzene is an aromatic hydrocarbon that, with sufficient cumulative lifetime doses, can cause acute myelogenous leukemia. Because of its volatility and solvent properties, it was used in the printing industry in inks, ink solvents, and cleaning agents from the 1930s to the 1970s. This analysis represents the first known attempt to gather and synthesize the available data on historical airborne benzene concentrations in printing facilities and exposures to pressmen. The sources of fugitive benzene vapors from printing operations have been identified as evaporation from ink fountains, exposed sections of the printing cylinder, the paper web, the paper post exit, and spilled ink. In addition, specific activities that could lead to benzene exposure, such as filling the fountains, using solvents to clean the press, and using solvents as personal cleaning agents, potentially occurred multiple times per work period. Eighteen studies were identified that reported workplace airborne concentrations in printing facilities between 1938 and 2006. Typical benzene air concentrations, considering both personal and area samples of various durations, were as high as 200 p.p.m. in the 1930s through the 1950s, 3-35 p.p.m. in the 1960s, 1.3-16 p.p.m. in the 1970s, 0.013-1 in the 1980s, and far less than 1 p.p.m. in the 1990s and 2000s. The decrease in benzene air concentrations by the late 1970s was likely to be linked to the decreased benzene content of printing materials, increased engineering controls, and to more stringent occupational exposure limits.

Sensitivity to input parameters of Mobile6.2-AERMOD simulated emissions and concentrations

This study investigates the sensitivity of simulated emissions and airborne NO2 and benzene concentrations to model input parameters. Emission factors were estimated using Mobile6.2 and ambient concentrations were estimated using AERMOD. The simulation was performed for Huron Church Road in Windsor, Ontario, Canada, an arterial road 9 km in length with an average vehicle speed of 50 km/h. Eight scenarios were developed such that one input parameter was changed at a time in the first seven scenarios and compared with the base case. Results showed that emission factors were most sensitive to the choice of vehicle composition (Ontario versus default), followed by the choice of vehicle age distribution (Ontario versus default), and the average speed of vehicles. Simulated concentrations were sensitive to the hour-of-day variation in emission (mainly due to variation in vehicle counts) and when this was not considered, the annual mean concentrations were likely overestimated by up to 27% and maximum hourly concentrations were underestimated. The findings provide insights into determining the level of details of input parameters required for estimation of emissions and concentrations.

Airborne benzene exposures from cleaning metal surfaces with small volumes of petroleum solvents

Airborne benzene concentrations were measured in a room with controlled air exchange during surface cleaning with two petroleum-based solvents (a paint thinner and an engine degreaser). The solvents were spiked with benzene to obtain target concentrations of 0.001, 0.01, and 0.1% by volume in the liquid. Personal samples on the worker and area samples up to 1.8m away were collected over 12 events (n=84 samples) designed to examine variation in exposure with solvent type, cleaning method (rag wipe or spatula scrape), surface area cleaned, air exchange rate, solvent volume applied, and distance from the cleaned surface. Average task breathing zone concentrations of benzene represented by 18-32 min time-weighted averages were 0.01 ppm, 0.05 ppm, and 0.27 ppm, when the solvents contained approximately 0.003, 0.008, and 0.07% benzene. Solvent benzene concentration, volume applied, and distance from the handling activities had the greatest effect on airborne concentrations. The studied solvent products containing 0.07% benzene (spiked) did not exceed the current OSHA permissible exposure limit of 1 ppm (averaged over 8h) or the ACGIH Threshold Limit Value of 0.5 ppm, in any of the tested short-term exposure scenarios. These data suggest that, under these solvent use scenarios, petroleum-based solvent products produced in the United States after 1978 likely did not produce airborne benzene concentrations above those measured if the concentration was less than 0.1% benzene.

Comparison of exposure measurements to near field–far field modeled results for benzene and base solvents during a cleaning process using plain or 0.1% benzene spiked toluene and xylene

It has been reported that the presence of ≤0.1% benzene in base solvents often used for cleaning is likely to result in exposure concentrations above the current OSHA PEL. This prediction was based upon calculations that depend largely on the concentration of benzene assumed to be present in a solvent mixture. Measurements of exposure during work simulations and more comprehensive modeling studies show that many factors other than the benzene content of the bulk solvent influence personal and area vapor concentrations. This study examines benzene exposure due to trace amounts of benzene in solvents available recently, and whether exposure in excess of the OSHA benzene standard occurs when 10 and 50 mL of base solvents containing up to 0.1% benzene are used during a manual cleaning process in a poorly ventilated room. Breathing zone (BZ) concentrations were measured for benzene, toluene and xylene during repetitions of a cleaning procedure using a small cloth to wipe a metal paint tray with 10 and 50 mL of consumer-grade toluene and xylene alone and toluene spiked with 0.1% benzene. Air samples were collected in the breathing zone (BZ) for 15 min to determine the short-term exposure. Separate 2 hr samples were collected in the BZ and general area to obtain time-weighted average (TWA) exposure concentrations. All samples were analyzed with a GC–FID utilizing NIOSH Method 1501. A near field–far field (NF–FF) model was used in conjunction with Monte Carlo simulation to predict airborne benzene, toluene, and xylene concentrations and to quantify uncertainty in the input parameters of the model. Variables including solvent evaporation time and air movement around the worker during the work activity were analyzed over a range of possible values. The result after 105 iterations of Monte Carlo simulation was a range of possible outcomes and the likelihood that each would occur; these outcomes are compared to the measured airborne concentrations. Cleaning the metal pan with 10–50 mL of toluene or xylene with or without 0.1% benzene did not result in benzene exposures in excess of either the OSHA PEL 8-hr TWA (1.0 ppm) or action level (0.5 ppm). The ratio of predicted or modeled to measured benzene concentration ranged from 0.42 to 2.1. The ratio of predicted or modeled to measured xylene and toluene concentration ranged from 0.92 to 3.7. Application of the NF–FF model under the conditions studied indicates a reasonable degree of reliability in forecasting airborne solvent concentrations under the conditions studied.

Benzene exposure in refinery workers: ExxonMobil Joliet, Illinois, USA (1977-2006)

While petroleum industry studies have indicated low benzene exposure potential for refinery workers, most provide limited data for assessing job or task-related benzene exposures. This study characterizes job and task-specific airborne benzene concentrations and variability over time for the ExxonMobil refinery in Joliet, Illinois from 1977 to 2006. A database of 2289 industrial hygiene air samples, including 1145 non-task (≥180 min) personal samples and 480 task-related (<180 min) personal samples, were analyzed. Samples were grouped by operational status, job, and task. Benzene concentrations were determined for each job category and task bin, with additional analyses conducted to determine whether benzene concentrations changed over time. The results indicate that the benzene concentrations for non-task and task samples were relatively low. For all non-task samples, the arithmetic mean benzene concentration was 0.12 part per million (ppm). The most frequently sampled workers (process technicians during routine operations) had an arithmetic mean benzene concentration of 0.038 ppm. The most frequently sampled task bin (blinding and breaking) had an arithmetic mean benzene concentration of 1.0 ppm. This study provides benzene air concentration data that can be used in combination with job histories to reconstruct historical benzene exposures for workers at the Joliet Refinery over the past 30 years.

Comparison of modeled and measured concentrations of airborne benzene from the use of petroleum-based solvents spiked with low levels of benzene

Airborne benzene concentrations were measured in a room with controlled air exchange during surface cleaning with two petroleum-based solvents (a paint thinner and an engine degreaser). The solvents were spiked with benzene to obtain target concentrations of 0.001, 0.01, and 0.1% by volume in the liquid. Personal samples on the worker and area samples up to 1.8 m away were collected over 12 events (n = 84 samples) designed to examine variation in exposure with solvent type, cleaning method (rag wipe or spatula scrape), surface area cleaned, air exchange rate, solvent volume applied, and distance from the cleaned surface. Average task breathing zone concentrations of benzene represented by 18–32 min time-weighted averages were 0.01 ppm, 0.05 ppm, and 0.27 ppm, when the solvents contained approximately 0.003, 0.008, and 0.07% benzene. Solvent benzene concentration, volume applied, and distance from the handling activities had the greatest effect on airborne concentrations. The studied solvent products containing 0.07% benzene (spiked) did not exceed the current OSHA permissible exposure limit of 1 ppm (averaged over 8 h) or the ACGIH Threshold Limit Value of 0.5 ppm, in any of the tested short-term exposure scenarios. These data suggest that, under these solvent use scenarios, petroleum-based solvent products produced in the United States after 1978 likely did not produce airborne benzene concentrations above those measured if the concentration was less than 0.1% benzene.

Characterization of cancer risk from airborne benzene exposure

Airborne benzene is a ubiquitous environmental air pollutant. However, research regarding ambient environmental benzene exposures and leukemogenesis is lacking. Alternatively, occupational exposure to significantly elevated levels of benzene is associated with acute myeloid leukemia (AML). This investigation uses ambient air monitoring data from six counties in the state of Florida to characterize the extrapolated cancer risk from airborne benzene concentrations. The study uses both a regulatory and comparative risk analysis methodology to appropriately frame “risk” for the public. Between the years 2003 and 2006, 3794 air samples were collected from 23 monitoring stations distributed in Broward, Duval, Orange, Miami-Dade, Hillsborough, and Pinellas counties. The mean benzene concentrations by site ranged from 0.18 to 3.58 ppb. Extrapolated cumulative lifetime exposures ranged from 0.036 to 0.702 ppm-years. Regulatory risk analysis resulted in cancer risk estimates ranging from 4.37 × 10 −6 to 8.56 × 10 −5, all of which exceed the Florida Department of Environmental Protection acceptable risk of 1 × 10 −6. Comparative analysis with the epidemiologic literature indicates the association between benzene exposure and AML is related to cumulative exposures far in excess of 1 ppm-years, with the likely threshold for benzene-induced leukemogenesis of ⩾50 ppm-years cumulative exposure. Based upon the results of this investigation, it is unreasonable to anticipate AML cases in Florida residents as a result of ambient airborne benzene concentrations.

Occupational Exposures Associated with Petroleum-Derived Products Containing Trace Levels of Benzene

Benzene may be present as a trace impurity or residual component of mixed petroleum products due to refining processes. In this article, the authors review the historical benzene content of various petroleum-derived products and characterize the airborne concentrations of benzene associated with the typical handling or use of these products in the United States, based on indoor exposure modeling and industrial hygiene air monitoring data collected since the late 1970s. Analysis showed that products that normally contained less than 0.1% v/v benzene, such as paints and paint solvents, printing solvents and inks, cutting and honing oils, adhesives, mineral spirits and degreasers, and jet fuel typically have yielded time-weighted average (TWA) airborne concentrations of benzene in the breathing zone and surrounding air ranging on average from <0.01 to 0.3 ppm. Except for a limited number of studies where the benzene content of the product was not confirmed to be <0.1% v/v, airborne benzene concentrations were also less than current occupational exposure limits (e.g., threshold limit value of 0.5 ppm and permissible exposure limit of 1.0 ppm) based on exceedance fraction calculations. Exposure modeling using Monte Carlo techniques also predicted 8-hr TWA near field airborne benzene concentrations ranging from 0.002 to 0.4 ppm under three hypothetical solvent use scenarios involving mineral spirits. The overall weight-of-evidence indicates that the vast majority of products manufactured in the United States after about 1978 contained <0.1% v/v benzene, and 8-hr TWA airborne concentrations of benzene in the workplace during the use of these products would not have been expected to exceed 0.5 ppm under most product use scenarios. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a document containing exposure modeling scenarios and results, historical benzene content of petroleum-derived products, and air monitoring results.]

Biological monitoring of low benzene exposure in Italian traffic policemen

A comparative evaluation of urinary biomarkers was carried out to characterize benzene exposure in a group of 100 traffic policemen of the city of Parma (Italy). All subjects were monitored once, in two consecutive days characterized by similar climatic conditions but preceded by two windy days. Benzene ambient concentration measured by municipal air monitoring stations was 1 μg/m 3 (Day 1) and 2 μg/m 3 (Day 2). Personal exposure to ambient concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) was assessed by using Radiello ® passive-diffusive samplers in a subgroup of 24 workers. Benzene metabolites, t, t-muconic acid ( t, t-MA) and S-phenylmercapturic acid ( S-PMA) were determined by isotopic dilution liquid chromatography– tandem mass spectrometry on spot urine samples collected at the end of the shift. Urinary benzene (U-B) was determined by solid-phase microextraction gas chromatography–mass spectrometry. Airborne benzene concentration expressed as median [and interquartile range] was 6.07 [0.28–9.53] μg/m 3, as assessed by personal sampling. Urinary concentrations of biomarkers in the whole group were 41.8 [34.1–89.8] μg/g creatinine for t, t-MA, 0.67 [0.23–1.32] μg/g creatinine for S-PMA, and 0.16 [0.13–0.26] μg/l for U-B. Smokers eliminated significantly higher concentrations of unchanged BTEX and benzene metabolites than non-smokers ( p < 0.05). When traffic policemen were distinguished into indoor ( n = 31) and outdoor workers, no significant differences were observed for either airborne benzene or urinary biomarkers. Significantly lower concentrations of S-PMA and U-B were determined in samples collected at Day 1 as compared to Day 2 ( p < 0.0001 and p = 0.003, respectively) suggesting that these biomarkers are enough sensitive and specific to detect changes in airborne benzene concentration even at few μg/m 3.

Simulation of Benzene Exposure during Use of a Mineral Spirit Solvent to Clean Elevator Bearing Housings

ABSTRACT An exposure simulation was conducted to reconstruct and assess a sheet-metal worker's historical exposure to benzene associated with the degreasing and cleaning of parts and equipment during the repair of a soybean elevator head pulley. The simulation was based on an employee description of the specific activities performed in the 1980s. Bulk solvent and airborne benzene concentrations associated with the degreasing and cleaning of parts and equipment using a bucket of mineral spirits solvent and soaked shop towels were measured during the simulation. The mineral solvent was spiked with benzene to represent the historical product formulation. Benzene concentrations in personal and background air samples were below the limits of analytical detection. These data were used to estimate a worker's inhalation and dermal exposure to benzene from the cleaning and degreasing task. The total dose of approximately 0.2 mg benzene estimated based on the simulation results is approximately equivalent to that received from non-occupational sources by individuals living in urban areas. This study demonstrated the utility of an exposure simulation in reconstructing and assessing historical worker exposures in a situation where no useful exposure data were available to characterize the exposure of interest.