Environmental and biological monitoring of benzene during self-service automobile refueling

False positives and false negatives in benzene biological monitoring

Benzene is a commonly used industrial chemical that is a significant environmental pollutant. Occupational health specialists and industrial toxicologists are concerned with determining the exact amount of exposure to chemicals in the workplace. There are two main approaches to assess chemical exposure; air monitoring and biological monitoring. Air monitoring has limitations, which biological monitoring overcomes and could be used as a supplement to it. However, there are several factors that influence biological monitoring results. It would be possible to assess exposure more accurately if these factors were taken into account. This study aimed to review published papers for recognizing and discussing parameters that could affect benzene biological monitoring. Two types of effects can be distinguished: positive and negative effects. Factors causing positive effects will increase the metabolite concentration in urine more than expected. Furthermore, the parameters that decrease the urinary metabolite level were referred to as false negatives. From the papers, sixteen influential factors were extracted that might affect benzene biological monitoring results. Identified factors were clarified in terms of their nature and mechanism of action. It is also important to note that some factors influence the quantity and quality of the influence of other factors. As a result of this study, a decision-making protocol was developed for interpreting the final results of benzene biological monitoring.

Occupational fatigue and health of gas station workers: A review

BACKGROUND

Occupational health factors such as shift work, sleep, fatigue, and work environment jeopardise the health and safety of gas station workers. This calls for new research to investigate how the working environment and characteristics impact the occupational health of workers at gas stations. However, minimal research has been conducted in this field, especially those involving psychological and behavioural factors, occupational stress, and so forth.

OBJECTIVE

This review was performed to investigate the present condition of the occupational risk of gas station workers in this safety-critical position.

METHODS

Five databases (Web of Science, ScienceDirect, PubMed, Google Scholar, and PsycINFO) were searched for relevant peer-reviewed studies. Results were selected according to these criteria: studies on fatigue, shift work, sleep, and physical and mental health of gas station employees; published on or before November 11, 2021; papers in English.

RESULTS

Twenty studies were considered for the final analysis. The results showed that shift work at gas stations leads to psychological and physiological problems. The psychological consequences included anxiety, stress, and depression, while the physiological consequences included biochemical changes and lifestyle consequences.

CONCLUSION

Shift work and the specific working environment of gas station employees adversely affect their sleep, stress levels, physical and mental health, and turnover intention. This systematic review allowed us to consider the occupational risk factors that can lead to sickness or accidents and contribute to reducing these risk factors. Realistic countermeasures ought to be established and interventions must be explored to mitigate risks to life, property, and the environment in operating gas stations.

Correlation between Workers’ Characteristics and Health Complaints Due to Exposure to Organic Solvents in the Sidoarjo Offset Printing

Introduction: Organic solvents are chemicals that are often used by the printing industry and contain Benzene, Toluene, and Xylene which are toxic to humans. Chemicals that contain organic solvents are ink, glue, and others. Workers who are regularly exposed to organic solvents can have health complaints. The purpose of this study was to determine the correlation between workers’ characteristics and health complaints due to exposure to organic solvents in the Sidoarjo offset printing. Methods: This research was an observational study with cross sectional design. Population in this research was 30 workers. The sampling technique used simple random sampling and from the calculation results were obtained 24 respondents. This study had an independent variable, which was workers’ characteristics consisting of age, smoking habits, and work tenure. The dependent variable was health complaints of printing workers. Data collection used questionnaires and interviews. The research data were analyzed using fisher’s exact test to show the correlation between workers’ characteristics and health complaints. Results: The result of the analysis test found that there was no correlation between age (p=0.386) and smoking habits (p=0.376) with health complaints of workers. Moreover, the analysis test showed that work tenure variable had a correlation with health complaints of workers (p=0.041). Conclusion: A factor related to health complaints of workers was work tenure.Keywords: health complaints, organic solvents, worker characteristics

Correlation between Workers’ Characteristics and Health Complaints Due to Exposure to Organic Solvents in the Sidoarjo Offset Printing

Introduction: Organic solvents are chemicals that are often used by the printing industry and contain Benzene, Toluene, and Xylene which are toxic to humans. Chemicals that contain organic solvents are ink, glue, and others. Workers who are regularly exposed to organic solvents can have health complaints. The purpose of this study was to determine the correlation between workers’ characteristics and health complaints due to exposure to organic solvents in the Sidoarjo offset printing. Methods: This research was an observational study with cross sectional design. Population in this research was 30 workers. The sampling technique used simple random sampling and from the calculation results were obtained 24 respondents. This study had an independent variable, which was workers’ characteristics consisting of age, smoking habits, and work tenure. The dependent variable was health complaints of printing workers. Data collection used questionnaires and interviews. The research data were analyzed using fisher’s exact test to show the correlation between workers’ characteristics and health complaints. Results: The result of the analysis test found that there was no correlation between age (p=0.386) and smoking habits (p=0.376) with health complaints of workers. Moreover, the analysis test showed that work tenure variable had a correlation with health complaints of workers (p=0.041). Conclusion: A factor related to health complaints of workers was work tenure.Keywords: health complaints, organic solvents, worker characteristics

Gasoline Vapor Emissions During Vehicle Refueling Events in a Vehicle Fleet Saturated With Onboard Refueling Vapor Recovery Systems: Need for an Exposure Assessment

Background: Gasoline contains large proportions of harmful chemicals, which can be released during vehicle refueling. Onboard Refueling Vapor Recovery (ORVR) can reduce these emissions, but there is limited research on the system's efficacy over time in an actual vehicle fleet. The aims of this study are: (1) determine the feasibility of using an infrared camera to view vapor emissions from refueling; (2) examine the magnitude of refueling-related emissions in an ORVR-saturated fleet, to determine need for an exposure-assessment. Methods: Using an infrared camera optimized for optical gas imaging of volatile organic chemicals, refueling was recorded for 16 vehicles at six gas stations. Pumps were inspected for damage, refueling shut-off valve functioning, and presence of Stage II Vapor Recovery. Vehicle make/model and age were recorded or estimated. Results: Vapor emissions were observed for 14 of 16 vehicles at each station, with severity varying substantially by vehicle make/model and age. Use of an infrared camera allowed for identification of vapor sources and timing of release, and for visualizing vapor trajectories. Discussion: Notably emissions occurred not only at the beginning and end of refueling but also throughout, in contrast to a prior study which did not detect increases in atmospheric hydrocarbon levels mid-refueling. Future studies are vitally needed to determine the risk to individuals during typical refueling in an ORVR saturated vehicle fleet. We recommend comprehensive exposure-assessment including real-time monitoring of emitted volatile organic compounds paired with infrared gas-imaging and measurement of internal dose and health effects of gas station customers.

Assessment of exposure of gas station attendants in Sri Lanka to benzene, toluene and xylenes

Exposure to benzene, toluene and p-, m-, o-xylene (BTX) was studied in 29 gas station attendants and 16 office workers in Sri Lanka. The aim of this study was to assess the exposure level and identify potential exposure mitigating measures. Pre- and post-shift samples of end-exhaled air were collected and analysed for BTX on a thermal desorption gas chromatography mass spectrometry system (TD-GC-MS). Urine was collected at the same timepoints and analysed for a metabolite of benzene, S-phenyl mercapturic acid (SPMA), using liquid chromatography-mass spectrometry (LC-MS). Environmental exposure was measured by personal air sampling and analysed by gas chromatography flame ionization detection (GC-FID). Median (range) breathing zone air concentrations were 609 (65.1-1960) μg/m³ for benzene and 746 (<5.0-2770) μg/m³ for toluene. Taking into account long working hours, 28% of the measured exposures exceeded the ACGIH threshold limit value (TLV) for an 8-h time-weighted average of 1.6 mg/m³ for benzene. Xylene isomers were not detected. End-exhaled air concentrations were significantly increased for gas station attendants compared to office workers (p < 0.005). The difference was 1-3-fold in pre-shift and 2-5-fold in post-shift samples. The increase from pre-to post-shift amounted to 5-15-fold (p < 0.005). Pre-shift BTX concentrations in end-exhaled air were higher in smokers compared to non-smokers (p < 0.01). Exposure due to self-reported fuel spills was related to enhanced exhaled BTX (p < 0.05). The same was found for sleeping at the location of the gas station between two work-shifts. Benzene in end-exhaled air was moderately associated with benzene in the breathing zone (r = 0.422; p < 0.001). Median creatinine-corrected S-phenyl mercapturic acid (SPMA) was similar in pre- and post-shift (2.40 and 3.02 μg/g) in gas station attendants but increased in office workers (from 0.55 to 1.07 μg/g). In conclusion, working as a gas station attendant leads to inhalation exposure and occasional skin exposure to BTX. Smoking was identified as the most important co-exposure. Besides taking preventive measure to reduce exposure, the reduction of working hours to 40 h per week is expected to decrease benzene levels below the current TLV.

Predictors of blood volatile organic compound levels in Gulf coast residents

To address concerns among Gulf Coast residents about ongoing exposures to volatile organic compounds, including benzene, toluene, ethylbenzene, o-xylene, and m-xylene/p-xylene (BTEX), we characterized current blood levels and identified predictors of BTEX among Gulf state residents. We collected questionnaire data on recent exposures and measured blood BTEX levels in a convenience sample of 718 Gulf residents. Because BTEX is rapidly cleared from the body, blood levels represent recent exposures in the past 24 h. We compared participants' levels of blood BTEX to a nationally representative sample. Among nonsmokers we assessed predictors of blood BTEX levels using linear regression, and predicted the risk of elevated BTEX levels using modified Poisson regression. Blood BTEX levels in Gulf residents were similar to national levels. Among nonsmokers, sex and reporting recent smoky/chemical odors predicted blood BTEX. The change in log benzene was -0.26 (95% CI: -0.47, -0.04) and 0.72 (0.02, 1.42) for women and those who reported odors, respectively. Season, time spent away from home, and self-reported residential proximity to Superfund sites (within a half mile) were statistically associated with benzene only, however mean concentration was nearly an order of magnitude below that of cigarette smokers. Among these Gulf residents, smoking was the primary contributor to blood BTEX levels, but other factors were also relevant.

Human biomarker interpretation: the importance of intra-class correlation coefficients (ICC) and their calculations based on mixed models, ANOVA, and variance estimates

Human biomonitoring is the foundation of environmental toxicology, community public health evaluation, preclinical health effects assessments, pharmacological drug development and testing, and medical diagnostics. Within this framework, the intra-class correlation coefficient (ICC) serves as an important tool for gaining insight into human variability and responses and for developing risk-based assessments in the face of sparse or highly complex measurement data. The analytical procedures that provide data for clinical and public health efforts are continually evolving to expand our knowledge base of the many thousands of environmental and biomarker chemicals that define human systems biology. These chemicals range from the smallest molecules from energy metabolism (i.e., the metabolome), through larger molecules including enzymes, proteins, RNA, DNA, and adducts. In additiona, the human body contains exogenous environmental chemicals and contributions from the microbiome from gastrointestinal, pulmonary, urogenital, naso-pharyngeal, and skin sources. This complex mixture of biomarker chemicals from environmental, human, and microbiotic sources comprise the human exposome and generally accessed through sampling of blood, breath, and urine. One of the most difficult problems in biomarker assessment is assigning probative value to any given set of measurements as there are generally insufficient data to distinguish among sources of chemicals such as environmental, microbiotic, or human metabolism and also deciding which measurements are remarkable from those that are within normal human variability. The implementation of longitudinal (repeat) measurement strategies has provided new statistical approaches for interpreting such complexities, and use of descriptive statistics based upon intra-class correlation coefficients (ICC) has become a powerful tool in these efforts. This review has two parts; the first focuses on the history of repeat measures of human biomarkers starting with occupational toxicology of the early 1950s through modern applications in interpretation of the human exposome and metabolic adverse outcome pathways (AOPs). The second part reviews different methods for calculating the ICC and explores the strategies and applications in light of different data structures.

Real-time monitoring of respiratory absorption factors of volatile organic compounds in ambient air by proton transfer reaction time-of-flight mass spectrometry

Respiratory absorption factors (AFs) are essential parameters in the evaluation of human health risks from toxic volatile organic compounds (VOCs) in ambient air. A method for the real time monitoring of VOCs in inhaled and exhaled air by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) has been developed to permit the calculation of respiratory AFs of VOCs. Isoprene was found to be a better breath tracer than O₂, CO₂, humidity, or acetone for distinguishing between the expiratory and inspiratory phases, and a homemade online breath sampling device with a buffer tube was used to optimize signal peak shapes. Preliminary tests with seven subjects exposed to aromatic hydrocarbons in an indoor environment revealed mean respiratory AFs of 55.0%, 55.9%, and 66.9% for benzene, toluene, and C8-aromatics (ethylbenzene and xylenes), respectively. These AFs were lower than the values of 90% or 100% used in previous studies when assessing the health risks of inhalation exposure to hazardous VOCs. The mean respiratory AFs of benzene, toluene and C8-aromatics were 66.5%, 70.2% and 82.3% for the three female subjects; they were noticeably much higher than that of 46.4%, 45.2% and 55.3%, respectively, for the four male subjects.

Toxicity of methyl tertiary-butyl ether on human blood lymphocytes

Methyl tertiary-butyl ether (MTBE) is a synthetic solvent widely used as oxygenate in unleaded gasoline. Few studies have addressed the cellular toxicity of MTBE on some cell lines, and so far, no comprehensive study has been conducted to investigate the probable immunotoxicity of this compound. In this study, the toxicity of MTBE on human blood lymphocytes was evaluated. Blood lymphocytes were isolated from healthy male volunteers' blood, using Ficoll polysaccharide followed by gradient centrifugation. Cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, glutathione levels, and damage to mitochondria and lysosome were determined in blood lymphocytes after 6-h incubation with different concentrations of MTBE (0.1, 0.5, 1, and 2 mM). Our results showed that MTBE, in particular, decreased cell viability, which was associated with significant increase at intracellular ROS level and toxic alterations in mitochondria and lysosomes in human blood lymphocytes. Moreover, it was shown that MTBE strongly provoked lipid peroxidation and also depleted glutathione level at higher concentrations. Interestingly, MTBE exhibited its cytotoxic effects at low concentrations that may resemble to its concentrations in human blood following occupational and environmental exposure. It is therefore concluded that MTBE was capable of inducing oxidative stress and damage to mitochondria and lysosomes in human lymphocytes at concentrations ranging from 5 to 40 μg/L, which may be present in human blood as a result of environmental exposure.

Glutathione S-Transferase Gene Polymorphisms: Modulator of Genetic Damage in Gasoline Pump Workers

This study investigated genetic damage in gasoline pump workers using the cytokinesis blocked micronucleus (CBMN) assay. Blood and urine samples were collected from 50 gasoline pump workers and 50 control participants matched with respect to age and other confounding factors except for exposure to benzene through gasoline vapors. To determine the benzene exposure, phenol was analyzed in urinary samples of exposed and control participants. Urinary mean phenol level was found to be significantly high (P < 0.05) in exposed workers. The CBMN frequency was found to be significantly higher in gasoline pump workers (6.70 ± 1.78) when compared to control individuals (2.20 ± 0.63; P < 0.05). We also investigated influence of polymorphisms of GSTM1, GSTT1, and GSTP1 genes on CBMN frequency. The individuals having GSTM1 and GSTT1 null genotypes had significantly higher frequency of CBMN (P < 0.05). Our study indicates that chronic and long-term exposure of gasoline vapors can increase genotoxic risk in gasoline pump workers.

Breath analysis: technical developments and challenges in the monitoring of human exposure to volatile organic compounds

At present, there is a growing concern about human quality of life. In particular, there is an awareness of the impact of volatile organic compounds (VOCs) on the environment and human health, so the monitoring of human exposure to VOCs is an increasingly urgent need. Biomonitoring is theoretically more accurate compared with traditional ambient air monitoring, and it plays an essential role in human environmental exposure assessment. Breath analysis is a biomonitoring method with many advantages, which is applicable to assessments of human exposure to a large number of VOCs. Techniques are being developed to improve the sensitivity and precision of breath analysis based on in-direct and direct measurements which will be reviewed in this paper. This paper briefly reviews the frequently used methods in both of these categories, specifically highlighting some promising new techniques. Furthermore, this review also provides theoretical background knowledge about the use of breath analysis as a biomonitoring tool for human exposure assessment. A review of the application of breath analysis to human exposure monitoring during last two decades is also provided according to occupational/non-occupational exposure. Obstacles and potential challenges in this field are also summarized. Based on the gradual improvements in the theoretical basis and technology reviewed in this paper, breath analysis is an enormous potential approach for the monitoring of human exposure to VOCs.

New Look at BTEX: Are Ambient Levels a Problem?

Benzene, toluene, ethylbenzene, and xylene (BTEX) are retrieved during fossil fuel extraction and used as solvents in consumer and industrial products, as gasoline additives, and as intermediates in the synthesis of organic compounds for many consumer products. Emissions from the combustion of gasoline and diesel fuels are the largest contributors to atmospheric BTEX concentrations. However, levels indoors (where people spend greater than 83% of their time) can be many times greater than outdoors. In this review we identified epidemiological studies assessing the noncancer health impacts of ambient level BTEX exposure (i.e., nonoccupational) and discussed how the health conditions may be hormonally mediated. Health effects significantly associated with ambient level exposure included sperm abnormalities, reduced fetal growth, cardiovascular disease, respiratory dysfunction, asthma, sensitization to common antigens, and more. Several hormones including estrogens, androgens, glucocorticoids, insulin, and serotonin may be involved in these health outcomes. This analysis suggests that all four chemicals may have endocrine disrupting properties at exposure levels below reference concentrations (i.e., safe levels) issued by the U.S. Environmental Protection Agency. These data should be considered when evaluating the use of BTEX in consumer and industrial products and indicates a need to change how chemicals present at low concentrations are assessed and regulated.

Health risk assessment of ambient air concentrations of benzene, toluene and xylene (BTX) in service station environments

A comprehensive evaluation of the adverse health effects of human exposures to BTX from service station emissions was carried out using BTX exposure data from the scientific literature. The data was grouped into different scenarios based on activity, location and occupation and plotted as Cumulative Probability Distributions (CPD) plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ) at 50% (CEXP50) and 95% (CEXP95) exposure levels. HQ50 and HQ95 > 1 were obtained with benzene in the scenario for service station attendants and mechanics repairing petrol dispensing pumps indicating a possible health risk. The risk was minimized for service stations using vapour recovery systems which greatly reduced the benzene exposure levels. HQ50 and HQ95 < 1 were obtained for all other scenarios with benzene suggesting minimal risk for most of the exposed population. However, HQ50 and HQ95 < 1 was also found with toluene and xylene for all scenarios, suggesting minimal health risk. The lifetime excess Cancer Risk (CR) and Overall Risk Probability for cancer on exposure to benzene was calculated for all Scenarios and this was higher amongst service station attendants than any other scenario.

An evidence-based analysis of epidemiologic associations between lymphatic and hematopoietic cancers and occupational exposure to gasoline

The presence of benzene in motor gasoline has been a health concern for potential increased risk of acute myelogenous leukemia and perhaps other lymphatic/hematopoietic cancers for approximately 40 years. Because of the widespread and increasing use of gasoline by consumers and the high exposure potential of occupational cohorts, a thorough understanding of this issue is important. The current study utilizes an evidence-based approach to examine whether or not the available epidemiologic studies demonstrate a strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers. Among 67 epidemiologic studies initially identified, 54 were ranked according to specific criteria relating to the relevance and robustness of each study for answering the research question. The 30 highest-ranked studies were sorted into three tiers of evidence and were analyzed for strength, specificity, consistency, temporality, dose-response trends and coherence. Meta statistics were also calculated for each general and specific lymphatic/hematopoietic cancer category with adequate data. The evidence-based analysis did not confirm any strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers based on the epidemiologic studies available to date. These epidemiologic findings, combined with the evidence showing relatively low occupational benzene vapor exposures associated with gasoline formulations during the last three decades, suggest that current motor gasoline formulations are not associated with increased lymphatic/hematopoietic cancer risks related to benzene.

The use of biomonitoring data in exposure and human health risk assessment: benzene case study

Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10(-5) excess cancer risk (2.9 µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.

The possibilities will take your breath away: breath analysis for assessing environmental exposure

Human breath is the gaseous exchange with the blood and thus contains trace organic contaminants and metabolites representative of environmental doses. Sampling and analysis of gaseous components in human breath offers a noninvasive and quick means of qualitatively and quantitatively assessing internalized doses of environmental contaminants. Although the humid and complex nature of breath is a challenge for detection of part-per-trillion to part-per-billion concentrations of environmental contaminants, recent advances in chemical analysis and instrumentation are allowing determination of environmental exposure and disease detection.

Differential gene expression profiles of human leukemia cell lines exposed to benzene and its metabolites

Benzene is a well-known environmental pollutant that can induce hematotoxicity, aplastic anemia, acute myelogenous leukemia, and lymphoma. Benzene toxicity is likely mediated through metabolites induced by means of multiple pathways. Although benzene metabolites are known to induce oxidative stress and disrupt the cell cycle, the mechanism underlying leukemogenesis is not fully understood. The aim of this study was to analyze the genome-wide expression profiles of human promyelocytic leukemia HL-60 cells that had been exposed to benzene and its metabolites. This was carried out using whole human genome oligonucleotide microarrays to ascertain potential biomarkers. Genes that were differentially expressed (>1.5-fold and p-values <0.05) after exposure to benzene (BZ), hydroquinone (HQ), and 1,4-benzoquinone (BQ) were then classified with GO, KEGG and GSEA pathway annotation. All genes that were identified were then functionally categorized as being involved in the cell cycle, the p53 signaling pathway, apoptosis, the MAPK signaling pathway, or the T cell receptor signaling pathway. Functionally important genes were further validated by means of real-time RT-PCR. The results showed that EGR1, PMAIP1, AR, CCL2, CD69, HSPA8, SLC7A11, HERPUD1, ELK1, and MKI57 genes altered their expression profiles. Similar expression profiles were also found in human erythromyeloblastoid leukemia K562 cells and in human leukemic monocyte lymphoma U937 cells. In conclusion, gene expression profiles along with GO, KEGG and GSEA pathway annotation analysis have provided an insight into the leukemogenesis as well as highlighted potential gene-based biomarkers of human leukemia cell lines when they are exposed to benzene and its metabolites.

Trends of VOC exposures among a nationally representative sample: Analysis of the NHANES 1988 through 2004 data sets

Exposures to volatile organic compounds (VOCs) are ubiquitous due to emissions from personal, commercial and industrial products, but quantitative and representative information regarding long term exposure trends is lacking. This study characterizes trends from1988 to 2004 for the 15 VOCs measured in blood in five cohorts of the National Health and Nutrition Examination Survey (NHANES), a large and representative sample of U.S. adults. Trends were evaluated at various percentiles using linear quantile regression (QR) models, which were adjusted for solvent-related occupations and cotinine levels. Most VOCs showed decreasing trends at all quantiles, e.g., median exposures declined by 2.5 (m, p-xylene) to 6.4 (tetrachloroethene) percent per year over the 15 year period. Trends varied by VOC and quantile, and were grouped into three patterns: similar decreases at all quantiles (including benzene, toluene); most rapid decreases at upper quantiles (ethylbenzene, m, p-xylene, o-xylene, styrene, chloroform, tetrachloroethene); and fastest declines at central quantiles (1,4-dichlorobenzene). These patterns reflect changes in exposure sources, e.g., upper-percentile exposures may result mostly from occupational exposure, while lower percentile exposures arise from general environmental sources. Both VOC emissions aggregated at the national level and VOC concentrations measured in ambient air also have declined substantially over the study period and are supportive of the exposure trends, although the NHANES data suggest the importance of indoor sources and personal activities on VOC exposures. While piecewise QR models suggest that exposures of several VOCs decreased little or any during the 1990's, followed by more rapid decreases from 1999 to 2004, questions are raised concerning the reliability of VOC data in several of the NHANES cohorts and its applicability as an exposure indicator, as demonstrated by the modest correlation between VOC levels in blood and personal air collected in the 1999/2000 cohort. Despite some limitations, the NHANES data provides a unique, long term and direct measurement of VOC exposures and trends.

Review of pesticide urinary biomarker measurements from selected US EPA children's observational exposure studies

Children are exposed to a wide variety of pesticides originating from both outdoor and indoor sources. Several studies were conducted or funded by the EPA over the past decade to investigate children’s exposure to organophosphate and pyrethroid pesticides and the factors that impact their exposures. Urinary metabolite concentration measurements from these studies are consolidated here to identify trends, spatial and temporal patterns, and areas where further research is required. Namely, concentrations of the metabolites of chlorpyrifos (3,5,6-trichloro-2-pyridinol or TCPy), diazinon (2-isopropyl-6-methyl-4-pyrimidinol or IMP), and permethrin (3-phenoxybenzoic acid or 3-PBA) are presented. Information on the kinetic parameters describing absorption and elimination in humans is also presented to aid in interpretation. Metabolite concentrations varied more dramatically across studies for 3-PBA and IMP than for TCPy, with TCPy concentrations about an order of magnitude higher than the 3-PBA concentrations. Temporal variability was high for all metabolites with urinary 3-PBA concentrations slightly more consistent over time than the TCPy concentrations. Urinary biomarker levels provided only limited evidence of applications. The observed relationships between urinary metabolite levels and estimates of pesticide intake may be affected by differences in the contribution of each exposure route to total intake, which may vary with exposure intensity and across individuals.

Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling

Benzene, toluene, m/p-xylene and o-xylene (BTX) are toxic volatile organic compounds and ubiquitous air pollutants. Smoking and consumer products are indoor sources of BTX, whereas traffic and industrial activities are primary sources contributing to outdoor levels of BTX. The aim of this study was to characterize exposure of children to BTX by personal air sampling using diffusive samplers and by analysis of end-exhaled air. For this study, 101 children of 10-11 years of age were recruited from four primary schools in Southern Turkey during the warm season (May 2008). Two schools were situated in a residential area near primary and secondary iron and steel works (Payas) and two schools were located in a non-industrialized city (Iskenderun). The children and their parents were visited at home for an interview and to identify possible sources of BTX in the residence. Median concentrations of benzene determined by diffusive samplers were higher in Payas (4.1 microg/m(3)) than in Iskenderun (2.7 microg/m(3), p<0.001). For toluene, no differences were observed, whereas for xylene isomers air concentrations tended to be lower for children living in Payas. The median end-exhaled air concentrations were 8.2, 29, 3.8, and 5.7 pmol/L for benzene, toluene, m/p-xylene and o-xylene, respectively (Payas), and 6.9, 25, 4.9, and 6.0 pmol/L, respectively (Iskenderun). Concentrations of toluene in end-exhaled air were 50% higher in children living with household members who smoked indoors (p<0.05) and benzene in end-exhaled air was more than 3-fold higher for those children who were exposed to tobacco smoke inside a vehicle (p<0.001). End-exhaled concentrations of benzene were also higher in children living in a residence with an attached garage (p<0.05). These exposure modifying factors were not identified when using the results obtained with diffusive samplers.

Permeation of gasoline, diesel, bioethanol (E85), and biodiesel (B20) fuels through six glove materials

Biofuels and conventional fuels differ in terms of their evaporation rates, permeation rates, and exhaust emissions, which can alter exposures of workers, especially those in the fuel refining and distribution industries. This study investigated the permeation of biofuels (bioethanol 85%, biodiesel 20%) and conventional petroleum fuels (gasoline and diesel) through gloves used in occupational settings (neoprene, nitrile, and Viton) and laboratories (latex, nitrile, and vinyl), as well as a standard reference material (neoprene sheet). Permeation rates and breakthrough times were measured using the American Society for Testing and Materials F739-99 protocol, and fuel and permeant compositions were measured by gas chromatography/mass spectrometry. In addition, we estimated exposures for three occupational scenarios and recommend chemical protective clothing suitable for use with motor fuels. Permeation rates and breakthrough times depended on the fuel-glove combination. Gasoline had the highest permeation rate among the four fuels. Bioethanol (85%) had breakthrough times that were two to three times longer than gasoline through neoprene, nitrile Sol-Vex, and the standard reference materials. Breakthrough times for biodiesel (20%) were slightly shorter than for diesel for the latex, vinyl, nitrile examination, and the standard neoprene materials. The composition of permeants differed from neat fuels, e.g., permeants were significantly enriched in the lighter aromatics including benzene. Viton was the best choice among the tested materials for the four fuels tested. Among the scenarios, fuel truck drivers had the highest uptake via inhalation based on the personal measurements available in the literature, and gasoline station attendants had highest uptake via dermal exposure if gloves were not worn. Appropriate selection and use of gloves can protect workers from dermal exposures; however, current recommendations from the National Institute for Occupational Safety and Health should be revised to account for contemporary fuel formulations that routinely contain ethanol.

Benzene exposure: an overview of monitoring methods and their findings

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.

Sampling of benzene in environmental and exhaled air by solid-phase microextraction and analysis by gas chromatography-mass spectrometry

Benzene is classified as a Group I carcinogen by the International Agency for Research on Cancer (IARC). The risk assessment for benzene can be performed by monitoring environmental and occupational air, as well as biological monitoring through biomarkers. The present work developed and validated methods for benzene analysis by GC/MS using SPME as the sampling technique for ambient air and breath. The results of the analysis of air in parks and avenues demonstrated a significant difference, with average values of 4.05 and 18.26 microg m(-3), respectively, for benzene. Sampling of air in the occupational environment furnished an average of 3.41 and 39.81 microg m(-3). Moreover, the correlations between ambient air and expired air showed a significant tendency to linearity (R (2) = 0.850 and R (2) = 0.879). The results obtained for two groups of employees (31.91 and 72.62 microg m(-3)) presented the same trend as that from the analysis of environmental air.

Toward an "omic" physiopathology of reactive chemicals: thirty years of mass spectrometric study of the protein adducts with endogenous and xenobiotic compounds

Cancer and degenerative diseases are major causes of morbidity and death, derived from the permanent modification of key biopolymers such as DNA and regulatory proteins by usually smaller, reactive molecules, present in the environment or generated from endogenous and xenobiotic components by the body's own biochemical mechanisms (molecular adducts). In particular, protein adducts with organic electrophiles have been studied for more than 30 [see, e.g., Calleman et al., 1978] years essentially for three purposes: (a) as passive monitors of the mean level of individual exposure to specific chemicals, either endogenously present in the human body or to which the subject is exposed through food or environmental contamination; (b) as quantitative indicators of the mean extent of the individual metabolic processing which converts a non-reactive chemical substance into its toxic products able to damage DNA (en route to cancer induction through genotoxic mechanisms) or key proteins (as in the case of several drugs, pesticides or otherwise biologically active substances); (c) to relate the extent of protein modification to that of biological function impairment (such as enzyme inhibition) finally causing the specific health damage. This review describes the role that contemporary mass spectrometry-based approaches employed in the qualitative and quantitative study of protein-electrophile adducts play in the discovery of the (bio)chemical mechanisms of toxic substances and highlights the future directions of research in this field. A particular emphasis is given to the measurement of often high levels of the protein adducts of several industrial and environmental pollutants in unexposed human populations, a phenomenon which highlights the possibility that a number of small organic molecules are generated in the human organism through minor metabolic processes, the imbalance of which may be the cause of "spontaneous" cases of cancer and of other degenerative diseases of still uncharacterized etiology. With all this in mind, it is foreseen that a holistic description of cellular functions will take advantage of new analytical methods based on time-integrated metabolomic measurements of a new biological compartment, the "adductome," aimed at better understanding integrated organism response to environmental and endogenous stressors.

ATSDR evaluation of health effects of benzene and relevance to public health

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Benzene. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of benzene. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.

Multipronged evaluation of genotoxicity in Indian petrol-pump workers

Petrol (gasoline) contains a number of toxicants. This study used human biomonitoring to evaluate the genotoxic effects of exposure to benzene in petrol fumes in 100 Indian petrol-pump workers (PPWs) and an equal number of controls. The study was corroborated with in silico assessments of the Comet assay results from the human biomonitoring study. An in vitro study in human lymphocytes was also conducted to understand the genotoxicity of benzene and its metabolites. In a subset of the population studied, higher blood benzene levels were detected in the PPWs (n = 39; P < 0.01) than the controls (n = 18), and 100-250 ppb benzene was also detected in air samples from the petrol pumps. PPWs had higher levels of DNA damage than the controls (P < 0.01). In addition, the micronucleus assay was performed on lymphocytes from a subset of the subjects, and the micronucleus frequency for PPWs was significantly higher (n = 39; 14.79 +/- 3.92 per thousand) than the controls (n = 18; 7.54 +/- 3.00 per thousand). Human lymphocytes were treated in vitro with benzene and several of its metabolites and assayed for DNA damage with the Comet assay. Benzene and its metabolites produced significant (P < 0.05) levels of DNA damage at and above concentrations of 10 microM. The metabolite, p-benzoquinone, produced the greatest amount of DNA damage, followed by hydroquinone > benzene > catechol > 1,2,4,-benzenetriol > muconic acid. This study demonstrates that, using sensitive techniques, it is possible to detect human health risks at an early stage when intervention is possible. possible.

Variability of albumin adducts of 1,4-benzoquinone, a toxic metabolite of benzene, in human volunteers

A putative haematotoxic and leukaemogenic metabolite of benzene, 1,4-benzoquinone (1,4-BQ), reacts rapidly with macromolecules. The authors previously characterized levels of the albumin (Alb) adduct (1,4-BQ-Alb) of this reactive species in populations of workers exposed to benzene. Since high levels of 1,4-BQ-Alb were also measured in unexposed workers from those investigations, the current study was initiated to determine potential sources of 1,4-BQ in the general population. A single blood sample was collected from 191 healthy subjects from the Research Triangle area, NC, USA, to determine the baseline 1,4-BQ-Alb levels and contributing sources. The median 1,4-BQ-Alb at baseline was 550?pmol?g(-1) Alb (interquartile range 435-814?pmol?g(-1)). A second blood sample was collected approximately 3 months later from a subgroup of 33 subjects to estimate the within- and between-person variation in 1,4-BQ-Alb. Standardized questionnaires were administered to collect information about demographic, dietary and lifestyle factors. Multiple linear regression models identified several significant contributors to 1,4-BQ-Alb levels, including gender, body mass index (BMI), the gender-BMI interaction, automobile refuelling, smoking status, and consumption of fruit and the artificial sweetener, aspartame. The authors predicted that these background levels of 1,4-BQ-Alb were equivalent to occupational exposures between 1 and 3 parts per million of benzene. Mixed effects linear models indicated that the random variation in adduct levels was about equally divided between and within subjects. The observations indicate that levels of 1,4-BQ-Alb cover a wide range in the general population, and they support the hypotheses that demographic, diet and lifestyle factors are contributing sources.

Relationships between levels of volatile organic compounds in air and blood from the general population

The relationships between levels of volatile organic compounds (VOCs) in blood and air have not been well characterized in the general population where exposure concentrations are generally at parts per billion levels. This study investigates relationships between the levels of nine VOCs, namely, benzene, chloroform, 1,4-dichlorobenzene, ethylbenzene, methyl tert-butyl ether (MTBE), tetrachloroethene, toluene, and m-/p- and o-xylene, in blood and air from a stratified random sample of the general US population. We used data collected from 354 participants, including 89 smokers and 265 nonsmokers, aged 20-59 years, who provided samples of blood and air in the National Health and Nutrition Examination Survey (NHANES) 1999-2000. Demographic and physiological characteristics were obtained from self-reported information; smoking status was determined from levels of serum cotinine. Multiple linear regression models were used to investigate the relationships between VOC levels in air and blood, while adjusting for effects of smoking and demographic factors. Although levels of VOCs in blood were positively correlated with the corresponding air levels, the strength of association (R(2)) varied from 0.02 (ethylbenzene) to 0.68 (1,4-DCB). Also the blood-air relationships of benzene, toluene, ethylbenzene, and the xylenes (BTEX) were influenced by smoking, exposure-smoking interactions, and by gender, age, and BMI, whereas those of the other VOCs were not. Interestingly, the particular exposure-smoking interaction for benzene was different from those for toluene, ethylbenzene, and the xylenes. Whereas smokers retained more benzene in their blood at increasing exposure levels, they retained less toluene, ethylbenzene, and xylenes at increasing exposure levels. Investigators should consider interaction effects of exposure levels and smoking when exploring the blood-air relationships of the BTEX compounds in the general population.

ATSDR evaluation of potential for human exposure to benzene

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the toxicological profile for benzene. The primary purpose of this article is to provide interested individuals with environmental information on benzene that includes production data, environmental fate, potential for human exposure, analytical methods, and a listing of regulations and advisories.

Toward better exposure assessment strategies--the new NIOSH initiative

NIOSH has embarked on a project to update its exposure sampling strategies manual. The current NIOSH strategy has a number of limitations. This is an opportunity to develop a robust and comprehensive exposure assessment strategy. Some of the key features of such a strategy are outlined. The importance of accurate professional judgment and exposure modeling is discussed. Bayesian statistics offers a rational approach to integrating sampling data, professional judgments, and the outputs of exposure models in a comprehensive framework.

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

OBJECTIVE

Personal exposure to airborne benzene is influenced by various outdoor and indoor sources. The first aim of this study was to assess the benzene exposure of a sample of urban inhabitants living in an inner-city neighborhood of Florence, Italy, excluding exposure from active smoking. The secondary objective was to differentiate the personal exposures according to personal usage patterns of the vehicles.

METHODS

A sample of 67 healthy non-smokers was monitored by passive samplers during two 4-weekday campaigns in winter and late spring. Simultaneously, benzene measurements were also taken for a subset of participants, inside and outside their houses. A 4-day time microenvironment activity diary was completed by each subject during each sampling period. Other relevant exposure data were collected by a questionnaire before the sampling. Additional data on urban ambient air benzene levels were also available from the public air quality network. The passive samplers, after automated thermal desorption, were analyzed by GC-FID.

RESULTS

Benzene personal exposure levels averaged 6.9 (SD=2.1) and 2.3 (SD=0.7) microg/m(3) in winter and spring, respectively. Outdoor and indoor levels showed high correlation in winter and poor in spring. In winter the highest benzene personal exposure levels were for people traveling by more public transport, followed by users of only car and by users of only bus respectively.

CONCLUSIONS

The time spent in-transport for work or leisure makes a major contribution to benzene exposure among Florentine non-smoking citizens. Indoor pollution and transportation means contribute significantly to individual exposure levels especially in winter season.

PBTK modeling demonstrates contribution of dermal and inhalation exposure components to end-exhaled breath concentrations of naphthalene

BACKGROUND

Dermal and inhalation exposure to jet propulsion fuel 8 (JP-8) have been measured in a few occupational exposure studies. However, a quantitative understanding of the relationship between external exposures and end-exhaled air concentrations has not been described for occupational and environmental exposure scenarios.

OBJECTIVE

Our goal was to construct a physiologically based toxicokinetic (PBTK) model that quantitatively describes the relative contribution of dermal and inhalation exposures to the end-exhaled air concentrations of naphthalene among U.S. Air Force personnel.

METHODS

The PBTK model comprised five compartments representing the stratum corneum, viable epidermis, blood, fat, and other tissues. The parameters were optimized using exclusively human exposure and biological monitoring data.

RESULTS

The optimized values of parameters for naphthalene were a) permeability coefficient for the stratum corneum 6.8 x 10(-5) cm/hr, b) permeability coefficient for the viable epidermis 3.0 x 10(-3) cm/hr, c) fat:blood partition coefficient 25.6, and d) other tissue:blood partition coefficient 5.2. The skin permeability coefficient was comparable to the values estimated from in vitro studies. Based on simulations of workers' exposures to JP-8 during aircraft fuel-cell maintenance operations, the median relative contribution of dermal exposure to the end-exhaled breath concentration of naphthalene was 4% (10th percentile 1% and 90th percentile 11%).

CONCLUSIONS

PBTK modeling allowed contributions of the end-exhaled air concentration of naphthalene to be partitioned between dermal and inhalation routes of exposure. Further study of inter- and intraindividual variations in exposure assessment is required to better characterize the toxicokinetic behavior of JP-8 components after occupational and/or environmental exposures.

Personal exposure to benzene from fuel emissions among commercial fishers: comparison of two-stroke, four-stroke and diesel engines

Commercial fishers are exposed to unburned hydrocarbon vapors and combustion products present in the emissions from their boat engines. The objective of this study was to measure personal exposure to benzene as a marker of fuel exposure, and to predict exposure levels across categories of carbureted two-stroke, four-stroke and diesel engines. A self-monitoring approach, employing passive monitors, was used to obtain measurements of personal exposure to benzene over time. Mixed-effect linear regression models were used to predict exposure levels, identify significant effects and determine restricted maximum likelihood estimates for within- and between-person variance components. Significant fixed effects for engine type and refueling a car or truck were identified. After controlling for refueling, predicted benzene exposure levels to fishers on boats equipped with two-stroke, four-stroke and diesel engines were 58.4, 38.9 and 15.7 microg/m3, respectively. The logged within-person variance component was 1.43, larger than the between-person variance component of 1.13, indicating that the total variation may be attributable to monitor placement, environmental conditions and other factors that change over time as well as differences between individual work practices. The health consequences of exposure to marine engine emissions are not known. The predicted levels are well below those at which health effects have been attributed, however.

Air samples versus biomarkers for epidemiology

BACKGROUND

It has been speculated on theoretical grounds that biomarkers are superior surrogates for chemical exposures to air samples in epidemiology studies.

METHODS AND RESULTS

Biomarkers were classified according to their position in the exposure-disease continuum-that is, parent compound, reactive intermediate, stable metabolite, macromolecular adduct, or measure of cellular damage. Because airborne exposures and these different biomarkers are time series that vary within and between persons in a population, they are all prone to measurement error effects when used as surrogates for true chemical exposures. It was shown that the attenuation bias in the estimated slope characterising a log exposure-log disease relation should decrease as the within- to between-person variance ratio of a given set of air or biomarker measurements decreases. To gauge the magnitudes of these variance ratios, a database of 12,077 repeated observations was constructed from 127 datasets, including air and biological measurements from either occupational or environmental settings. The within- and between-person variance components (in log scale, after controlling for fixed effects of time) and the corresponding variance ratios for each set of air and biomarker measurements were estimated. It was shown that estimated variance ratios of biomarkers decreased in the order short term (residence time < or =2 days) > intermediate term (2 days < residence time < or =2 months) > long term biomarkers (residence time >2 months). Overall, biomarkers had smaller variance ratios than air measurements, particularly in environmental settings. This suggests that a typical biomarker would provide a less biasing surrogate for exposure than would a typical air measurement.

CONCLUSION

Epidemiologists are encouraged to consider the magnitudes of variance ratios, along with other factors related to practicality and cost, in choosing among candidate surrogate measures of exposure.

Gene expression profile in bone marrow and hematopoietic stem cells in mice exposed to inhaled benzene

Acute myeloid leukemia and chronic lymphocytic leukemia are associated with benzene exposure. In mice, benzene induces chromosomal breaks as a primary mode of genotoxicity in the bone marrow (BM). Benzene-induced DNA lesions can lead to changes in hematopoietic stem cells (HSC) that give rise to leukemic clones. To gain insight into the mechanism of benzene-induced leukemia, we investigated the DNA damage repair and response pathways in total bone marrow and bone marrow fractions enriched for HSC from male 129/SvJ mice exposed to benzene by inhalation. Mice exposed to 100 ppm benzene for 6h per day, 5 days per week for 2 week showed significant hematotoxicity and genotoxicity compared to air-exposed control mice. Benzene exposure did not alter the level of apoptosis in BM or the percentage of HSC in BM. RNA isolated from total BM cells and the enriched HSC fractions from benzene-exposed and air-exposed mice was used for microarray analysis and quantitative real-time RT-PCR. Interestingly, mRNA levels of DNA repair genes representing distinct repair pathways were largely unaffected by benzene exposure, whereas altered mRNA expression of various apoptosis, cell cycle, and growth control genes was observed in samples from benzene-exposed mice. Differences in gene expression profiles were observed between total BM and HSC. Notably, p21 mRNA was highly induced in BM but was not altered in HSC following benzene exposure. The gene expression pattern suggests that HSC isolated immediately following a 2 weeks exposure to 100 ppm benzene were not actively proliferating. Understanding the toxicogenomic profile of the specific target cell population involved in the development of benzene-associated diseases may lead to a better understanding of the mechanism of benzene-induced leukemia and may identify important interindividual and tissue susceptibility factors.

Naphthalene and its biomarkers as measures of occupational exposure to polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAH) include compounds with two or more fused benzene rings, many of which are carcinogens. Industrial sources produce hundreds of PAH, notably in the coke- and aluminium-producing industries. Because PAH are distributed at varying levels between gaseous and particulate phases, exposure assessment has been problematic. Here, we recommend that occupational exposures to naphthalene be considered as a potential surrogate for occupational PAH exposure for three reasons. Naphthalene is usually the most abundant PAH in a given workplace; naphthalene is present almost entirely in the gaseous phase and is, therefore, easily measured; and naphthalene offers several useful biomarkers, including the urinary metabolites 1- and 2-hydroxynaphthalene. These biomarkers can be used to evaluate total-body exposure to PAH, in much the same way that 1-hydroxypyrene has been applied. Using data from published sources, we show that log-transformed airborne levels of naphthalene are highly correlated with those of total PAH (minus naphthalene) in several industries (creosote impregnation: Pearson r= 0.815, coke production: r= 0.917, iron foundry: r= 0.854, aluminium production: r= 0.933). Furthermore, the slopes of the log-log regressions are close to one indicating that naphthalene levels are proportional to those of total PAH in those industries. We also demonstrate that log-transformed urinary levels of the hydroxynaphthalenes are highly correlated with those of 1-hydroxypyrene among coke oven workers and controls (r= 0.857 and 0.876), again with slopes of log-log regressions close to one. These results support the conjecture that naphthalene is a useful metric for occupational PAH exposure. Since naphthalene has also been shown to be a respiratory carcinogen in several animal studies, it is also argued that naphthalene exposures should be monitored per se in industries with high levels of PAH.

Variability of environmental exposures to volatile organic compounds

Although studies of occupational exposure to volatile organic compounds (VOCs) often partition variability across groups, and between and within persons, those of environmental exposure to VOCs have not involved such partitioning. Using data from the Environmental Protection Agency's total exposure assessment methodology (TEAM) studies, we partitioned exposure variability across cities, and between and within persons for nine VOCs. The estimated variance components decreased in the order: within-person > between-person > across city. Despite their smaller magnitudes, estimates of between-person and across-city variance components were sufficiently large to provide reasonable contrast for informative epidemiology studies of most VOCs. Estimates of between-person variance components for environmental VOCs were similar to those published for occupational VOCs (groups defined by job and factory). However, estimates of within-person variance components were much greater for environmental VOCs, probably due to the greater diversity of locations (including the workplace) visited by the general public over time. For benzene and perchloroethylene, we used a simple model to calculate numbers of personal measurements required to relate the exposure level to health outcome statistically. About 10 times more personal measurements would be required to investigate perchloroethylene exposure as compared to benzene exposure; this disparity reflects the greater within-subject variability of perchloroethylene data compared to benzene data. We conclude that variability should be partitioned for environmental VOC exposures in much the same manner as for occupational exposures. There should be sufficient variability in the levels of most VOCs across cities and between subjects to provide reasonable contrast for informative epidemiology studies, as we illustrate for exposures to benzene. Yet, epidemiologists should be wary of investigating environmental VOCs without preliminary data with which to estimate the variance structure of exposure variables.

Benzene and naphthalene in air and breath as indicators of exposure to jet fuel

AIMS

To estimate exposures to benzene and naphthalene among military personnel working with jet fuel (JP-8) and to determine whether naphthalene might serve as a surrogate for JP-8 in studies of health effects.

METHODS

Benzene and naphthalene were measured in air and breath of 326 personnel in the US Air Force, who had been assigned a priori into low, moderate, and high exposure categories for JP-8.

RESULTS

Median air concentrations for persons in the low, moderate, and high exposure categories were 3.1, 7.4, and 252 microg benzene/m3 air, 4.6, 9.0, and 11.4 microg benzene/m3 breath, 1.9, 10.3, and 485 microg naphthalene/m3 air, and 0.73, 0.93, and 1.83 microg naphthalene/m3 breath, respectively. In the moderate and high exposure categories, 5% and 15% of the benzene air concentrations, respectively, were above the 2002 threshold limit value (TLV) of 1.6 mg/m3. Multiple regression analyses of air and breath levels revealed prominent background sources of benzene exposure, including cigarette smoke. However, naphthalene exposure was not unduly influenced by sources other than JP-8. Among heavily exposed workers, dermal contact with JP-8 contributed to air and breath concentrations along with several physical and environmental factors.

CONCLUSIONS

Personnel having regular contact with JP-8 are occasionally exposed to benzene at levels above the current TLV. Among heavily exposed workers, uptake of JP-8 components occurs via both inhalation and dermal contact. Naphthalene in air and breath can serve as useful measures of exposure to JP-8 and uptake of fuel components in the body.

Exposure assessment of monoterpenes and styrene: a comparison of air sampling and biomonitoring

BACKGROUND

Within- and between-worker variance components have seldom been reported for both environmental and biological data collected from the same persons.

AIMS

To estimate these variance components and their ratio for air contaminants and urinary metabolites in two different work environments and to predict the attenuation of exposure-response relationships based on these measures.

METHODS

Parallel measurements of air and urine were performed among workers exposed to monoterpenes in sawmills (urinary metabolite: verbenol) and styrene in reinforced plastics factories (urinary metabolite: mandelic acid).

RESULTS

Among the sawmill workers, variance components of the air and urinary verbenol results were similar; for the reinforced plastics workers the estimated between-worker variance component was greater for styrene in air than mandelic acid in urine. This suggests that attenuation bias would be about equal if air or biological monitoring were employed for monoterpene exposures, but would be greater if urinary mandelic acid were used instead of airborne styrene in an investigation of styrene exposure.

CONCLUSIONS

Personal air samplers provide data with similar or superior quality to urinary metabolites as measures of exposure to these monoterpenes in sawmills and styrene in reinforced plastics factories.

The effects of jet fuel on immune cells of fuel system maintenance workers

Jet fuel is a common occupational exposure among commercial and military maintenance workers. JP-8 jet fuel, a military formulation, has shown immunotoxic effects in mice, but little data exist for humans. The aim of this cross-sectional study was to determine whether immune cell counts in the peripheral blood were altered among tank entry workers at three Air Force bases. After adjusting for covariates, fuel system maintenance personnel (n = 45) were found to have significantly higher counts of white blood cells (P = 0.01), neutrophils (P = 0.05), and monocytes (P = 0.02) when compared with a low-exposure group (n = 78), but no differences were noted in the numbers of total lymphocytes, T-cells, T-helper cells, T-suppressor cells, natural killer cells, and B-cells. Investigations are needed to evaluate the functional ability of these cells to produce lymphokines and cytokines and modulate the immune system.

Passive sampling in combination with thermal desorption and gas chromatography as a tool for self-assessment of chemical exposure

Diffusive samplers for monitoring of air quality are user-friendly devices that can normally be operated by the user himself. Hence these samplers are suitable for self-assessment. Practical and work organisational aspects of self-assessment of chemical exposure were studied in different occupational settings. It was found that the diffusive sampler used in these studies, the Perkin-Elmer tube in combination with thermal desorption, worked well for the purpose and could be correctly handled by the individuals using it. The results from self-assessments agreed well with expert measurements carried out by an occupational hygienist. However, in order to obtain a sustainable system of self-assessment strong organizational support is needed.

Phase II collaborative pilot study: preliminary analysis of central neural effects from exposure to volatile anesthetics in the PACU

Nurses working in the PACU are occupationally exposed to volatile anesthetics that are exhaled by patients. Few studies have quantified this exposure using breath analysis or have characterized biological effects associated with this exposure. Isoflurane is a widely used anesthetic and is a strong respiratory depressant. Exposure to isoflurane has been shown to cause changes in breathing patterns at low doses. However, biological effects of isoflurane exposure have never been addressed in the occupational setting. This study investigates whether occupational exposure to anesthetic gases has a depressive effect on central neural control of breathing. In this study, concentrations of halogenated anesthetics were quantified in pre- and postshift breath samples of nurses working in the PACU on a Friday and the following Monday. After each breath sample was collected, an occlusion pressure measurement was taken as an indicator of central inspiratory drive. Cumulative nitrous oxide and halogenated anesthetics exposure was measured each day using personal sampling monitors placed close to the nurse's mouth. Exposure to nitrous oxide and isoflurane was significantly higher on Monday than on Friday (P <.001). Monday breath isoflurane concentrations (mean +/- SD) increased significantly from 43 +/- 30 parts per billion (ppb) in preshift breath samples to 124 +/- 57 ppb in postshift breath samples (P <.002). On Monday, there was a significant decrease in occlusion pressure from 1.2 +/- 0.37 cm H(2)O in preshift samples to 0.85 +/- 0.43 cm H(2)O in postshift samples (P =.05). There was no statistical difference in pre- versus postbreath isoflurane or occlusion pressure on Friday. These data indicate that after increased exposure to isoflurane, central neurorespiratory activity was depressed.

A review of the USEPA's single breath canister (SBC) method for exhaled volatile organic biomarkers

Exhaled alveolar breath can provide a great deal of information about an individual's health and previous exposure to potentially harmful xenobiotic materials. Because breath can be obtained non-invasively and its constituents directly reflect concentrations in the blood, its use has many potential applications in the field of biomarker research. This paper reviews the utility and application of the single breath canister (SBC) method of alveolar breath collection and analysis first developed by the US Environmental Protection Agency (USEPA) in the 1990s. This review covers the development of the SBC technique in the laboratory and its application in a range of field studies. Together these studies specifically show how the SBC method (and exhaled breath analysis in general) can be used to clearly demonstrate recent exposure to volatile organic compounds, to link particular activities to specific exposures, to determine compound-specific uptake and elimination kinetics, and to assess the relative importance of various routes of exposure (i.e. dermal, ingestion, inhalation) in multi-pathway scenarios. Specific investigations covered in this overview include an assessment of exposures related to the residential use of contaminated groundwater, exposures to gasoline and fuel additives at self-service gas stations, swimmers' exposures to trihalomethanes, and occupational exposures to jet fuel.