Benzene exposure: An overview of monitoring methods and their findings

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Abstract

Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person's total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,t-muconic acid (t,tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences in metabolic rates compared to occupational or animal doses, and the presence of polymorphisms need to be considered when evaluating risks from environmental exposures to individuals or potentially susceptible populations.

Introduction

Human exposure characterization is a necessary component of environmental and occupational epidemiological studies, risk characterizations and risk management. Exposure science links emissions of a toxicant with dose and public health [1], [2]. Adverse health effects of benzene, in particular blood diseases such as leukemia and aplastic anemia, were initially noted in occupational settings in which the benzene air concentrations were tens to hundreds of ppm [3], [4]. That observation, along with toxicological studies of benzene in animals resulted in the establishment of workplace standards in many countries limiting the air concentrations that workers can be exposed to (Table 1). Current epidemiological studies are still investigating what level of benzene exposure leads to blood diseases and other adverse effects in healthy workers, how to extrapolate health effects to environmental exposures and to provide evidence for risk characterization and management of benzene exposure to the public. The assessment of exposure is often the weakest portion of epidemiological studies and improved methods for extrapolation to environmental exposures based on direct inhalation and dermal exposure assessment and biomarker data are needed to be properly ascertain what health outcomes identified in occupational setting are relevant to the general population for current environmental exposures. This manuscript reviews benzene air concentrations and exposures in both occupational and environmental settings along with methodologies for sample collection and analysis. The impact of air concentrations outdoors, indoors and in transit along with activity patterns on personal exposure is discussed. The applicability of different biomarkers of benzene exposure across different magnitude of exposure is also evaluated.

Occupational exposures occur within the petrochemical industry and in manufacturing that require aromatic solvents or glues that contain benzene such as rubber production, shoe manufacturing, and printing [5], [6], [7], [8]. Environmental exposures to the general population are predominantly through inhalation due to benzene's volatility. Benzene is a component of gasoline, thus emissions from mobile sources are major contributors to the benzene air concentrations where gasoline engines are prevalent [9], [10], [11]. Benzene is also present in cigarette smoke so smokers and individuals who inhale environmental tobacco smoke (ETS) or second hand smoke (SHS) are exposed to benzene above background ambient air levels. A key to determining exposure is the understanding of activities of workers and populations at risk. The benzene levels in the microenvironment encountered and the activities and behaviors that lead to contact change with time [12], [13]. These parameters, combined with biomarker measurements can help define the exposure to dose relationships and lead to approaches that can define how best to reduce benzene exposures.

Section snippets

Air samples

To determine benzene and other non-polar volatile organic compounds (VOCs) air concentrations, the major pathway for benzene exposure, samples are collected from the air on either an adsorbent or by trapping whole air in a container. Passive vapor monitors or badges which collect VOCs based on diffusion are commonly used in occupational settings to measure ppm concentration levels present within the personal or breathing zone air as they present little burden to the wearer [14], [15]. Passive

Biomarkers

The measurement of benzene in blood, breath or urine definitively documents a benzene exposure. However, the biological resident time of benzene in the body is minutes to hours [102] so it is difficult to determine the actual and in some cases even the relative exposures across individuals from a single benzene measurement in blood or breath unless details of when the sample was collected relative to the exposure are known.

Discussion

Benzene exposures still commonly occur within both occupational and environmental settings, though they have been declining over the last several decades. Occupational exposures are now typically below the regulatory standard of 1 ppm and often below 0.1 ppm. However, identifying higher exposures, exceeding 10's of ppm exist in small, unregulated workplaces is an important data gap. Environmental exposures among the general population are much lower than occupational exposures, ranging from <1 to

Conflicts of interest

None declared.

Acknowledgement

The author is supported in part by the NIEHS sponsored UMDNJ Center for Environmental Exposures and Disease, Grant #: NIEHS P30ES005022.

References (139)

  • G. Tranfo

    Validation of an HPLC/MS/MS method with isotopic dilution for quantitative determination of trans,trans-muconic acid in urine samples of workers exposed to low benzene concentrations

    Journal of Chromatography B: Analytical Technologies in the Biomedical & Life Sciences

    (2008)
  • T. Schettgen

    Fast determination of urinary S-phenylmercapturic acid (S-PMA) and S-benzylmercapturic acid (S-BMA) by column-switching liquid chromatography–tandem mass spectrometry

    Journal of Chromatography B: Analytical Technologies in the Biomedical & Life Sciences

    (2008)
  • L. Sabatini

    Validation of an HPLC-MS/MS method for the simultaneous determination of phenylmercapturic acid, benzylmercapturic acid and o-methylbenzyl mercapturic acid in urine as biomarkers of exposure to benzene, toluene and xylenes

    Journal of Chromatography B: Analytical Technologies in the Biomedical & Life Sciences

    (2008)
  • O. Wong

    Regulation of occupational exposures in China [comment]

    Regulatory Toxicology & Pharmacology

    (2003)
  • P. Manini

    Environmental and biological monitoring of benzene exposure in a cohort of Italian taxi drivers

    Toxicology Letters

    (2006)
  • P. Manini

    Biological monitoring of low benzene exposure in Italian traffic policemen

    Toxicology Letters

    (2008)
  • P. Navasumrit

    Environmental and occupational exposure to benzene in Thailand

    Chemico-Biological Interactions

    (2005)
  • P. Navasumrit

    Potential health effects of exposure to carcinogenic compounds in incense smoke in temple workers

    Chemico-Biological Interactions

    (2008)
  • S. Gokhale et al.

    Source apportionment of human personal exposure to volatile organic compounds in homes, offices and outdoors by chemical mass balance and genetic algorithm receptor models

    Science of the Total Environment

    (2008)
  • S. Vainiotalo et al.

    Measurement of 16 volatile organic compounds in restaurant air contaminated with environmental tobacco smoke

    Environmental Research

    (2008)
  • B. Son et al.

    Volatile organic compounds concentrations in residential indoor and outdoor and its personal exposure in Korea [erratum appears in Environ Int 2004;29(February (8)):1109]

    Environment International

    (2003)
  • S.A. Fruin

    Reductions in human benzene exposure in the California South Coast Air Basin

    Atmospheric Environment

    (2001)
  • S. Batterman et al.

    Concentrations and emissions of gasoline and other vapors from residential vehicle garages

    Atmospheric Environment

    (2006)
  • S. Batterman et al.

    Migration of volatile organic compounds from attached garages to residences: a major exposure source

    Environmental Research

    (2007)
  • S.R. Kim et al.

    Concentrations of vehicle-related air pollutants in an urban parking garage

    Environmental Research

    (2007)
  • M.C. Fondelli

    Benzene exposure in a sample of population residing in a district of Florence, Italy

    Science of the Total Environment

    (2008)
  • A.L. Hinwood

    Volatile organic compounds in selected micro-environments

    Chemosphere

    (2006)
  • T. Schupp

    Benzene and its methyl-derivatives: derivation of maximum exposure levels in automobiles

    Toxicology Letters

    (2006)
  • S. Li

    Concentrations and risk assessment of selected monoaromatic hydrocarbons in buses and bus stations of Hangzhou, China

    Science of the Total Environment

    (2009)
  • J.-W. Lee et al.

    Actual commuter exposure to methyl-tertiary butyl ether, benzene and toluene while traveling in Korean urban areas

    Science of the Total Environment

    (2002)
  • D. Som

    Studies on commuters’ exposure to BTEX in passenger cars in Kolkata, India

    Science of the Total Environment

    (2007)
  • R.T. O’Donoghue

    Exposure to hydrocarbon concentrations while commuting or exercising in Dublin

    Environment International

    (2007)
  • P.J. Lioy

    Exposure analysis and assessment in the 21st century

    Inhalation Toxicology

    (1999)
  • J.J. Zhang et al.

    Human exposure assessment in air pollution systems

    The Scientific World Journal

    (2002)
  • R.A. Rinsky et al.

    Leukemia in benzene workers

    American Journal of Industrial Medicine

    (1981)
  • R.A. Rinsky

    Benzene and leukemia. An epidemiologic risk assessment

    New England Journal of Medicine

    (1987)
  • P.R.D. Williams et al.

    Benzene exposures associated with tasks performed on marine vessels (circa 1975 to 2000)

    Journal of Occupational & Environmental Hygiene

    (2005)
  • D.K. Verma et al.

    Benzene in gasoline and crude oil: occupational and environmental implications

    AIHA Journal: A Journal for the Science of Occupational & Environmental Health & Safety

    (2002)
  • L.A. Wallace

    The exposure of the general population to benzene

    Cell Biology & Toxicology

    (1989)
  • L. Wallace

    Environmental exposure to benzene: an update

    Environmental Health Perspectives

    (1996)
  • K. Sexton

    Estimating volatile organic compound concentrations in selected microenvironments using time-activity and personal exposure data

    Journal of Toxicology & Environmental Health Part A

    (2007)
  • F. Meneses

    A survey of personal exposures to benzene in Mexico City

    Archives of Environmental Health

    (1999)
  • R. Pristas

    Passive badges for compliance monitoring internationally

    American Industrial Hygiene Association Journal

    (1994)
  • T.H. Stock

    Evaluation of the use of diffusive air samplers for determining temporal and spatial variation of volatile organic compounds in the ambient air of urban communities

    Journal of the Air & Waste Management Association

    (2008)
  • G.C. Pratt

    A field comparison of volatile organic compound measurements using passive organic vapor monitors and stainless steel canisters

    Environmental Science & Technology

    (2005)
  • S. Wilbur

    ATSDR evaluation of potential for human exposure to benzene

    Toxicology & Industrial Health

    (2008)
  • J.D. Jeffers

    Real-time diode laser measurements of vapor-phase benzene

    Analytical Chemistry

    (2003)
  • P. Tzoumaka

    Experimental measurements of C2–C5 and C6–C10 in urban area of Thessaloniki, Greece

    Fresenius Environmental Bulletin

    (2008)
  • A. Clark

    Comparison of photoionization detection gas chromatography with a Tenax GC sampling tube procedure for the measurement of aromatic hydrocarbons in ambient air

    International Journal of Environmental Analytical Chemistry

    (1984)
  • E. Velasco

    Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 & 2003 field campaigns

    Atmospheric Chemistry and Physics

    (2007)
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