Benzene In Air Research Articles

Trans,trans-muconic acid as a biomarker of non-occupational environmental exposure to benzene.

Excretion of trans,trans-muconic acid (2,4-hexadienedioic acid; t,t-MA), a potential biomarker of low-level exposure to benzene, was determined in 32 smokers and 82 nonsmokers. In smokers the median background excretion of t,t-MA was 0.13 (0.06-0.39) mg/g creatinine and was significantly higher (P < 0.05) than the value of 0.065 (0.02-0.59) mg g creatinine in nonsmokers. For nonsmokers, the correlation between t,t-MA excretion and environmental exposure to benzene in ambient air, which was determined during the 8-day study period by personal diffusion samplers, was not significant (r = 0.164, P = 0.18). Nonsmokers living in the city tended to have higher t,t-MA excretion rates than nonsmokers living in the suburbs. However, the difference was only significant for nonsmokers from nonsmoking homes. For the same location (suburb or city), smoking at home leads to a marginal increase in t,t-MA excretion of the nonsmoking members of the household. In a further study with eight nonsmokers we found that dietary supplementation with 500 mg sorbic acid significantly increased (P < 0.001) the mean urinary t,t-MA excretion from 0.08 (0.04-0.12) to 0.88 (0.57-1.48) mg/24 h. Under study conditions 0.12% of the sorbic acid dose was excreted in urine as t,t-MA, thereby indicating that a typical dietary intake of 6-30 mg/day sorbic acid accounts for 10-50% of the background t,t-MA excretion in nonsmokers, and for 5-25% in smokers. As a consequence, sorbic acid in the diet is a significant confounding factor in assessing low-level benzene exposure if t,t-MA excretion in urine is used as a biomarker.

Determination of Benzene, Toluene and Xylene in Ambient Air of Calcutta for Three Years During Winter

Calcutta is known to have serious air pollution problems. Benzene, toluene and xylene (BTX) in the ambient air were monitored during the winter from 1992 to 1994 inclusive. Activated carbon traps were used for sampling and a simple packed column gas chromatography methodology was used for analyses in this study. Samples were collected in 5 locations in Calcutta. Concentrations were found to be much higher than that found in similar studies performed elsewhere. The average benzene concentrations during the winter in 1992, 1993 and 1994 were 1004 µg m−3, 7082 µg m−3 and 491 µg m−3 respectively. The average compositional ratios of benzene:toluene:xylene (B:T:X) in winter were 1:0.39:0.05, 1:0.16:0.04 and 1:0.26:0.13 for 1992, 1993 and 1994 respectively. The toluene/benzene concentration ratio in the samples varied from 1.033 at the end of summer to 0.092 at the end of winter. This variation has been determined to be the result of variation in atmospheric persistence of the released compounds due to thermal inversion. It is estimated that 5280 coal burning stoves per square kilometre are used for cooking in Calcutta. The median concentration of benzene, toluene and xylene in the smoke plume above the coal burning stove used for cooking, was found to be 5497 µg m−3, 4080 µg m−3, and 962 µg m−3 respectively. The compositional ratio of B:T:X for the coal burning cooking stoves was therefore 1:0.74:0.18. Automobile exhausts from different types of vehicles were also analysed for BTX. This study suggests that the primary sources of this high concentration of benzene are automobile exhaust and large number of coal burning stoves.

Geographical Distribution of Benzene in Air in Northwestern Italy and Personal Exposure

Geographical Distribution of Benzene in Air in Northwestern Italy and Personal Exposure

Geographical distribution of benzene in air in northwestern Italy and personal exposure.

Benzene is a solvent strictly related to some industrial activities and to automotive emissions. After the reduction in lead content of fuel gasoline, and the consequent decrease in octane number, an increase in benzene and other aromatic hydrocarbons in gasoline occurred. Therefore, an increase in the concentration of these chemicals in the air as primary pollutants and as precursors of photochemical smog could occur in the future. The objectives of this study were to describe the benzene air pollution at three sites in northwestern Italy throughout 1991 and 1994; to examine the relationship between benzene air pollution in indoor, outdoor, and personal air as measured by a group of nonsmoking university students; and to determine the influence of environmental tobacco smoke on the level of benzene exposure in indoor air environments. The results indicate a direct relationship between population density and levels of contamination; an indoor/outdoor ratio of benzene air pollution higher than 1 during day and night; a similar level of personal and indoor air contamination; and a direct relationship between levels of personal exposure to benzene and intensity of exposure to tobacco smoke. Human exposure to airborne benzene has been found to depend principally on indoor air contamination not only in the home but also in many other confined environments.

Development of a priority list of chemical mixtures occurring at 1188 hazardous waste sites, using the hazdat database

Under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund) section 104 mandate, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986 USC 9604 (i)(2), the Agency for Toxic Substances and Disease Registry (ATSDR) is to identify individual substances and combinations of substances that pose the greatest public health hazard at hazardous waste sites. This has led to certain mandated activities of the Agency, including development of toxicological profiles, identification of data gaps, and, ultimately, establishment of a research agenda. The Agency has also developed HazDat, a database that captures pertinent information from public health assessments conducted at hazardous waste sites. As a preliminary step, data from sites have been analysed to identify the combinations of chemicals found in various environmental media. The most frequently found combinations were perchloroethylene (PERC) and trichloroethylene (TCE) in water (23.5% of sites); chromium (Cr) and lead (Ph) in soil (20.5%); benzene and toluene in air (3.5%); PERC, 1,1,1-trichloroethane (1,1,1-TCA) and TCE in water (11.6%); Cr, cadmium (Cd) and Pb in soil (12.0%); and benzene, PERC and TCE in air (2.2%). The findings of this analysis can be enhanced by factoring into the algorithm paramenters such as toxicity, source contribution, and likelihood of human exposure similar to that used for the Agency's priority list of 275 single substances. Assessment of the impact of chemical mixtures on human health is a formidable task, and estimating the toxicity of such mixtures, including the role of chemical interactions, is an equally demanding challenge. Because limited experimental data exist for chemical interactions, alternative methods such as predictive approaches and in vitro techniques are needed to address the many substances and their potential combinations.

Monitoring of benzene, toluene and p-xylene in urban air with differential optical absorption spectroscopy technique

Instruments based on the differential optical absorption spectroscopy (DOAS) technique are used for monitoring air pollutants in urban areas all over the world. In Göteborg (Sweden) the DOAS technique has been used for several years for continuous monitoring of aromatic hydrocarbons and other traffic-related air pollutants. In the present study, measurements of benzene, toluene and p-xylene performed by DOAS have been evaluated. In an intercomparison study, adsorbent sampling and gas chromatography were used for measurements at the same sites as the DOAS instruments. The evaluation illustrated that the quality of the DOAS measurements was unsatisfactory even at concentrations exceeding the recommended lower limits. The proportions of benzene, toluene and p-xylene are usually uniform in vehicle polluted urban air. A significant deviation from the expected proportions may be used as an indication that the performance of a DOAS instrument should be checked.

On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.

There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration from 17 to 62.3 micrograms/m3 even if the actual distance was small. A larger increase was observed when a car was left with the engine running at a distance 2 m from the zero emission vehicle: We measured an increment of benzene concentrations from 15.2 to 174.4 micrograms/m3 with a car equipped with a catalytic converter, and from 19.1 to 386.3 micrograms/m3 with a car without such a converter.

On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry

On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry

Monitoring of benzene in the 10 μm and 14 μm region

We investigated the possibility of benzene monitoring in the ν 14-band in the 10 μm region and ν 4-band in the 14 μm region with regard to industrial applications. We were able to detect 80 ppm of benzene in ambient air.

Multicomponent vapor transport model for viscous, transitional, and molecular flow

A multicomponent vacuum flow and vapor transport model for a long outgassing tube has been developed and verified experimentally. The model includes advective and diffusive vapor transport processes for a wide range of gas flow, from viscous to molecular. Existing single component approaches to the separation of vacuum flow into molecular and viscous fractions have been extended to include multicomponent transport with partial advection and interdiffusion. A set of nonlinear partial differential equations describing vacuum flow and transport in a tube are derived and solved with an iterative numerical scheme. Comparison of model simulations with laboratory measurements of vapor transport in a long vacuum sampling tube showed that the model accurately represents the process of interdiffusion in all flow regimes. Advection was accurately simulated by the model for all vapor components in fully viscous flow. Partial advection and tube limited diffusion in the transition flow range were also well simulated by the model for an argon–air mixture, while benzene–air and 1,1,1-trichloroethane–air mixtures showed slightly less than predicted partial advection. Reduced advection with these latter compounds may be due to the many energy storage modes available to the multiatomic molecules, which result in less momentum transfer than would be predicted by methods that assume fully elastic collisions between molecules.

Ambient Air Benzene Concentrations in Canada (1989-1993): Seasonal and Day of Week Variations, Trends, and Source Influences

Abstract Since 1987, the Pollution Measurement Division of the Environmental Protection Service, Environment Canada, has operated a field program for measuring benzene in ambient air. With the cooperation of provincial and municipal environmental agencies, samples have been collected at over 30 urban and rural monitoring sites across the country. Samples are collected in evacuated canisters and analyzed by gas chromatography with a mass-selective detector. Using data from all sites, the composite average benzene concentration for Canada over the years 1989 to 1993 was 3.6 μg/m3 and the composite median was found to be 2.6 μ/m3. Benzene concentrations are highest at urban sites near major streets and at sites influenced by industrial sources. For eighteen urban and suburban trend sites (those with no nearby industrial sources), composite annual median benzene concentrations decreased by 20% between 1989 and 1993. For the same period, median benzene concentrations decreased by 33% at four trend sites with n...

Evaluation of biomarkers for occupational exposure to benzene.

To evaluate the relations between environmental benzene concentrations and various biomarkers of exposure to benzene. Analyses were carried out on environmental air, unmetabolised benzene in urine, trans, trans-muconic acid (ttMA), and three major phenolic metabolites of benzene; catechol, hydroquinone, and phenol, in two field studies on 64 workers exposed to benzene concentrations from 0.12 to 68 ppm, the time weighted average (TWA). Forty nonexposed subjects were also investigated. Among the five urinary biomarkers studied, ttMA correlated best with environmental benzene concentration (correlation coefficient, r = 0.87). When urinary phenolic metabolites were compared with environmental benzene, hydroquinone correlated best with benzene in air. No correlation was found between unmetabolised benzene in urine and environmental benzene concentrations. The correlation coefficients for environmental benzene and end of shift catechol, hydroquinone, and phenol were 0.30, 0.70, and 0.66, respectively. Detailed analysis, however, suggests that urinary phenol was not a specific biomarker for exposure below 5 ppm. In contrast, ttMA and hydroquinone seemed to be specific and sensitive even at concentrations of below 1 ppm. Although unmetabolised benzene in urine showed good correlation with atmospheric benzene (r = 0.50, P < 0.05), data were insufficient to suggest that it is a useful biomarker for exposure to low concentrations of benzene. The results from the present study also showed that both ttMA and hydroquinone were able to differentiate the background level found in subjects not occupationally exposed and those exposed to less than 1 ppm of benzene. This suggests that these two biomarkers are useful indices for monitoring low concentrations of benzene. Furthermore, these two metabolites are known to be involved in bone marrow leukaemogenesis, their applications in biological monitoring could thus be important in risk assessment. The good correlations between ttMA, hydroquinone, and atmospheric benzene, even at concentrations of less than 1 ppm, suggest that they are sensitive and specific biomarkers for benzene exposure.

A field method for sampling benzene in end-exhaled air.

A simple and reliable field method is presented for sampling and analysis of benzene in end-exhaled air. The sample is collected directly on an adsorbent tube while the subject exhales through a sampling device consisting of a modified peak expiratory flow meter. To ensure sampling of end-exhaled air, the temperature of the breath is monitored during expiration. The analytes subsequently are thermally desorbed and analyzed by gas chromatography. No sample preparation before analysis is needed, and therefore sample loss is minimized, shipping is easy, storage is possible, and clean up is unnecessary. All these steps have been major problems in earlier methods for breath analysis. The presented method has been applied to the monitoring of benzene. The separation of benzene from other components of exhaled air was good and the detection limit low (0.5 microgram/m3), and therefore benzene could be monitored in occupationally nonexposed nonsmokers. No carry-over in the sampling device or breakthrough could be detected. The samples were stable for at least a week. The combined precision in sampling and analysis was excellent, with a coefficient of variation of 13%.

Contamination of indoor air by toxic soil vapours: a screening risk assessment model

A simple steady-state model is derived for estimating the concentration of vapour-phase contaminants in indoor air, given the contaminant concentration in the soil. The model includes the key mechanisms of transport and dispersion—contaminant partitioning into the soil-vapour phase, molecular diffusion, suction flow, and ventilation rate. It is shown that indoor air concentrations are largely controlled by two variables: soil permeability, and the half-life for contaminant removal from soil. A worked example shows the effect of these two variables on the concentration of benzene in soil that would give rise to a concentration of benzene in indoor air of 5 ppb (the recently proposed U.K. Air Quality Standard).

Gasoline consumption and leukemia mortality and morbidity in 19 European countries: an ecological study.

It is widely recognized that exposure to benzene is a risk factor for leukemia; however, much remains to be clarified about the possible long-term health effects of exposures to low concentrations of benzene. With this in mind an ecological study was carried out in which both gasoline consumption data and data on leukemia mortality and incidence were collected for 19 European countries. Gasoline consumption was taken as an indication for exposure to benzene in ambient air. There appeared to be a weak inverse association between temporal trends in gasoline consumption and temporal trends in leukemia mortality. On the other hand, a weak positive association was found between the age-adjusted myeloid leukemia incidence in 14 areas and the gasoline consumption per square kilometer. However, both findings can easily be explained by other factors, such as changes in prognosis or differences in leukemia case ascertainment. This study is not supportive of an association between gasoline consumption and reported leukemia incidence and mortality rates.

Passive sampling for volatile organic compounds (VOCs) in air at environmentally relevant concentration levels

A sensitive and reliable method is described for the determination of aromatic and chlorinated hydrocarbons (benzene, toluene, o-, m-, p-xylene, trichloromethane, trichloroethane, trichloroethene and tetrachloroethene) in indoor and outdoor air at environmental concentration levels. The procedure can be easily extended to other VOCs. Using passive samplers the VOCs have been adsorbed onto charcoal during a four-week sampling period and subsequently desorbed with carbon disulfide. After injection with a cold split-splitless multi-injector the VOCs have been separated by capillary gas chromatography. Quantification has been achieved using an electron capture detector (ECD) and a flame ionization detector (FID) switched in series. A limit of about 1 μg/m3 for aromatic hydrocarbons and of about 0.01 μg/m3 for chlorinated hydrocarbons has been obtained. The procedure has been successfully applied in the framework of a field study to measure indoor and outdoor air concentrations in Essen and Borken, two differently polluted areas of Northrhine-Westphalia.

Determination of benzene, aniline and nitrobenzene in workplace air: a comparison of active and passive sampling

There have been numerous investigations on methods for assessing the relative performance of pumped and diffusive sampling techniques for the determination of airborne contaminants. Diffusive sampling is a convenient and cost-effective analytical tool for measuring exposure to chemical hazards in air and has been available as a replacement for pumped sampling for around 20 years. In spite of the considerable amount of work put into their evaluation, diffusive samplers have only been partially successful in replacing pumps. Generally, evaluation studies on diffusive samplers have been concentrated primarily on their accuracy at high concentrations, neglecting the vital aspect of their applicability at lower concentrations (below mg m 3 ) in the field. The present evaluation demonstrates that a Perkin-Elmer-type sampling tube, filled with Tenax TA and operated diffusively, provides a means of sampling that is sufficiently sensitive to measure benzene, aniline and nitrobenzene at concentrations as low as 0.10 mg m 3 . This method gives precise and accurate results that are well within the National Institute for Occupational Safety and Health (NIOSH) acceptability criteria of ±25% accuracy. No correlation is observed between active and diffusive sampling at concentration levels below 0.01 mg m 3 . Retention volumes, thermal desorption recoveries, sampling efficiencies, diffusive uptake rates and concentration effect on sampling performance were investigated. There are no previous reports, on determination of aniline and nitrobenzene in air by diffusive sampling and thermal desorption.

The evaluation of a tenax GR diffusive sampler for the determination of benzene and other volatile aromatics in outdoor air

The applicability of a tube-type diffusive sampler as an environmental monitor for benzene, toluene, ethylbenzene and xylene (BTEX) is reported. Uptake rates have been experimentally determined for a novel type adsorbent, Tenax GR, and compared to theoretical values. It is shown, that the uptake rates are virtually independent of environmental parameters within the experimental conditions studied. The response of the sampler to transient changes in concentrations has been determined in the laboratory. It is found that the sampler is capable of following an extreme concentration profile. Field comparisons with pumped samplers have been performed and good agreement is observed between the results of the two independent methods. The samplers have also been applied as environmental monitors at different locations.

Lyondell legal problems delay Arco sale of notes

Atlantic Richfield Co. (Arco) postponed the sale of $1 billion in debt securities linked to stock in Houstonbased Lyondell Petrochemical until a new investigation into Lyondell's alleged noncompliance with certain environmental laws is completed. A special audit committee appointed by Lyondell's board is conducting the investigation. At issue is the company's compliance with benzene air emission regulations of two process wastewater streams at Lyondell's Channelview, Tex., petrochemical complex and other environmental questions raised by a senior employee within Lyondell's legal department. A Lyondell spokeswoman declines to identify the employee or the additional allegations. Lyondell management, she says, has no reason to believe these allegations are valid. However, management takes seriously any concern raised by an employee. Lyondell reported to state and federal agencies that two pipes at Channelview containing wastewater streams with trace amounts of benzene were not included in its $55 m...

Benzene, toluene and xylenes in air, geographical distribution in the Piedmont region (Italy) and personal exposure

The objectives of this study were the determination of: (a) benzene (B), toluene (T) and xylene (X) air pollution in three sites of the Piedmont region (north-western Italy), (b) the relationship between BTX pollution in indoor, outdoor and personal air measured for a group of non-smoking university students, (c) the influence of environmental tobacco smoke on the level of BTX exposure for indoor air environments. Results indicate (i) a direct relationship between human density and level of contamination and higher toluene pollution, (ii) an indoor/outdoor ratio of > 1 for all the three aromatics, (iii) a similar level of personal and indoor air contamination. Human exposure to BTX air pollution has been found to depend principally on indoor air contamination, not only on home pollution, but also, probably on many other confined environments.