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PubMed2002

Biological monitoring of exposure to mixtures.

This short review is aimed at establishing general principles of biological monitoring for chemical mixtures. When interactions occur, they appear to be toxicokinetic in nature, often resulting from competition between two or more substances for the same biotransformation enzymes. A threshold is frequently observed for such an interaction, so that it might not influence the relationship between the absorbed dose and the value of the relevant biomarker. The extent of the interaction between pairs of chemicals also depends on the extent of biotransformation of each compound. As a result, the measurement of the parent compound or its metabolite will be differentially influenced by the presence of an interfering chemical. Biological limit values (BLV) are often established from the correlation between the bioindicator concentration in a given biological medium and the airborne concentration of the parent compound. When this relationship is derived from exposure to pure chemicals, it might not always yield an appropriate BLV for monitoring exposure to a mixture that includes this particular chemical. Under certain conditions such as the stability of mixture composition, a single biomarker such as 1-hydroxypyrene in PAH exposure can be used to reflect the overall exposure to a mixture. Finally, there is clearly a need for a greater research effort on the toxicology of mixtures to make biological monitoring a useful tool in occupational health.

Animals↗
PubMed2000

Toxicokinetic modelling of methyl formate exposure and implications for biological monitoring.

A toxicokinetic (TK) model was developed to describe the inhalation exposure in humans to methyl formate (MF), a catalyst used in foundries, and to discuss biological monitoring. The TK model consisted of four compartments: MF, the metabolites--methanol (MeOH) and formic acid (FA)--and, in addition, a urinary compartment describing the saturable reabsorption of FA. Levels of MeOH and FA in urine, from an experimental study (100 ppm MF, 8 h at rest), validated the present model. The TK model describes well the general behaviour of MeOH and FA in urine after MF exposure. A nonlinear and a linear relationship respectively, was predicted between MF exposure and FA or MeOH excretion in urine, and this has previously been seen after occupational MF exposure. The present model has been modified to simulate MeOH exposure as well. Generally low exposures (concentration or exercise) produce only marginal increases in FA urinary excretions, but when exposure is elevated, urinary FA excretion increases because of saturation in the mechanism of reabsorption. Using FA urinary excretion as the critical indicator, because of its link to health effects, an occupational exposure limit value for MF of no greater than 50 ppm should be selected (based on predictions with the TK model). MeOH in urine can be considered as a biomarker for MF at low exposure, because of lower background values and of a linear relationship with exposure. At higher exposures, however, FA could be used as a biomarker as it becomes progressively more sensitive. But the use of biological monitoring for MF is difficult because of individual variations in background values. Under the present state of knowledge both FA and MeOH should be used to estimate only group exposures, rather than individual exposures.

Environmental Monitoring↗
PubMed1997

Nicotinamide adenine dinucleotide synthetase activity in erythrocytes as a tool for the biological monitoring of lead exposure.

OBJECTIVE: The objective of this study was to evaluate the usefulness of nicotinamide adenine dinucleotide synthetase (NADS) activity for the biological monitoring of lead exposure. METHODS: The subjects were 76 male lead workers and 13 normal volunteers (7 males and 6 females). NADS activity and blood lead concentration (Pb-B) was determined in each subject. Delta-aminolevulinic acid dehydratase (ALAD) activity was determined in 58 lead workers out of 76 subjects. RESULTS: NADS activity in the lead workers ranged from 0.08 to 1.1 mumol/h per g of hemoglobin (gHb) and decreased linearly (r = -0.867) as Pb-B increased up to 81.6 micrograms/dl. The pattern of depressed activity of NADS was different from that of ALAD activity, which decreased rapidly and reached a plateau at the Pb-B level between 40 and 60 micrograms/dl. The Pb-B levels inducing 50% inhibition of the enzyme activities were calculated to be 43 micrograms/dl and 20 micrograms/dl for NADS and ALAD, respectively. At the Pb-B level of 40 micrograms/dl, NADS activity showed high validity (1.77) with predictivity of 0.92 at the cut-off level of 0.4 mumol/h per gHb, which were higher than those of ALAD activity. CONCLUSIONS: These results show an apparent dose-effect relationship of NADS activity versus Pb-B. NADS activity can be used for the biological monitoring of lead exposure.

Adult↗
PubMed1997

Occupational exposure to polycyclic aromatic hydrocarbons in a graphite-electrode producing plant: biological monitoring of 1-hydroxypyrene and monohydroxylated metabolites of phenanthrene.

OBJECTIVE: The objective of this study was to assess external and internal exposure to polycyclic aromatic hydrocarbons (PAHs) of workers who are employed in a graphite-electrode producing plant. Additionally we wanted to contribute to the question of biological limit values in order to reduce exposure to tolerable levels. METHODS: At five different working places 12 stationary and 16 personal air measurements were carried out to determine the concentrations of phenanthrene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene and dibenz[a, h]anthracene in air. In addition, we investigated the excretion of 1-, 2 + 9-, 3- and 4-hydroxyphenanthrene and of 1-hydroxypyrene in the urine of 67 workers by a very sensitive and practical high-performance liquid chromatographic (HPLC) method with fluorescence detection; 2- and 9-hydroxyphenanthrene could not be separated with our analytical method. RESULTS: During the production of graphite electrodes significantly higher PAH exposures were found in the baking and impregnation area than in the crushing, graphitisation and conditioning area. The results of personal air measurements (mean values of the sum of eight PAHs) are: 29.3 (baking), 23.4 (impregnation), 5.2 (crushing), 1.3 (graphitisation) and 0.4 microgram/m3 (conditioning). Stationary air measurements yielded similar concentrations. Workers employed in the baking and impregnation areas excreted the highest amount of PAH metabolites in urine. The 1-hydroxypyrene concentrations (median) were: 23.4 (baking), 22.0 (impregnation), 9.6 (crushing), 1.8 (graphitisation) and 2.3 micrograms/g creatinine (conditioning). The corresponding concentrations of the sum of monohydroxylated phenanthrene metabolites (median) were: 23.1, 36.0, 10.4, 4.6 and 7.6 micrograms/g creatinine. Within the monohydroxylated phenanthrene metabolites 3-hydroxyphenanthrene predominates with a percentage of 43%. Our results showed that a benzo[a]pyrene concentration in air of 2 micrograms/m3 would lead to 1-hydroxypyrene concentrations in urine of 20-74 micrograms/g creatinine. That means that corresponding values in the literature which lie between 4.4 and 6.2 micrograms/g creatinine are due to other conditions of exposure and cannot be applied to graphite-electrode producing plants. CONCLUSIONS: Although to date there are no obligatory biological exposure limits for metabolites of PAHs in urine, it must be concluded that the internal PAH exposure is too high at some work places in this plant, as is generally the case in graphite-electrode producing plants. This is probably caused by skin absorption of PAHs. So for the prevention of health hazards by PAH, internal exposure must be measured using biological monitoring. Although it has not been possible to establish biological exposure limits for PAHs until now, we suggest a reduction in skin contact with these substances and thereafter use of the 90th percentile of the results of biological monitoring as "action levels" for corrective measures.

Air↗
PubMedDate not supplied

[Occupational exposure to nickel in Tuscany: analysis of a biological monitoring register for the period 1991-1998].

OBJECTIVE: The study assesses the time trend in exposure to nickel among factory workers in Florence, via data on biological monitoring. A data-base of nickel in urinary samples (Ni-U mg/l) was created for the period 1991 to 1998. METHODS: The data-base contained 2.138 samples, measured by atomic absorption (GF-AAS),from 893 workers. Subjects came from 157 factories in various manufacturing sectors, especially electroplating, mechanical workshops, jewellery. RESULTS: Ni-U levels were correlated with manufacturing sector. The highest levels were found among workers from electroplating industries, where exposure was mainly due to water-soluble nickel compounds. The eight-year time trend showed a statistically significant decrease in Ni-U values, with a sharper drop during the last two-year period. Age, sex and number of samples per subject were not statistically related to this trend. CONCLUSION: The observed Ni-U decrease could be related to the efficacy of new legislation introduced in Italy during the study period (Law 626/94 and subsequent laws), but also to the intense labour inspection activities that officials of National Health Service performed, which were rightly focused on nickel exposure in different manufacturing sectors. This study confirms the usefulness for occupational risk evaluation of a biological monitoring data-base of routinely collected data.

Adult↗
PubMedDate not supplied

Assessment of occupational health risk from multiple exposure: review of industrial solvent interaction and implication for biological monitoring of exposure.

This review is a critical survey and evaluation of recent literature on solvent interactions for the assessment of health risk. It addresses the implications of multiple solvent exposures 1) by examining the influence of solvent-solvent and ethanol-solvent interactions on the biological indices of chemical exposure, and 2) by indicating how the eventual modifying effects can be considered in the biological monitoring of mixed exposure. Reviewed studies reveal the effects of toxicokinetic interactions on the biological parameters, and the gaps in our knowledge. The measurement of potentially toxic molecular species is suggested for the biological monitoring of multiple chemical exposure. This approach appears to be important for drawing better quantitative conclusions on the internal exposure to biologically active chemical species. Finally, research needs arising from the critical analysis of the literature are briefly described.

Biotransformation↗
PubMed1988

Biological monitoring of styrene: a review.

Recent literature about the biological monitoring of styrene-exposed workers is reviewed. Styrene primarily exhibits its toxicity on the central and peripheral nervous systems, although its mutagenicity and chromosome damaging ability also may be relevant. Uptake, transformation and excretion of styrene show that beside the usual biological indicators, such as urinary mandelic and phenylglyoxylic acids (main metabolites), other indicators also may be of interest. These include styrene in expired air, in blood or in urine. Moreover, intermediate or final metabolites such as styrene glycol or mandelic acid in blood also have been proven to be useful in the interpretation of individual values. The most widely used analytical methods for these indicators are gas or high performance liquid chromatography. Correlations between exposure and the different biological indicators mentioned above show that the most reliable indicators are mandelic acid (MA) in urine sampled at the end of the work shift (but not the first day of the week) and the sum of mandelic and phenylglyoxylic acids (MA + PGA) in urine sampled 16 hr after exposure (before the next shift). The biological exposure limit values corresponding to the threshold limit value-time-weighted average (TLV-TWA) of 50 ppm of styrene are 850 mg MA/g creatinine in the end-of-shift sample and 330 mg MA + PGA/g creatinine in the next-morning sample. Other biological indexes, such as styrene glycol (phenyl ethylene glycol) in blood or styrene in urine, look promising but require further research in field situations.

Absorption↗
PubMed1993

Pharmacokinetic modeling as a tool for biological monitoring.

The relationships between biological indicators and exposure or tissue burdens are determined by the pharmacokinetic behaviour of the chemical. They can be studied by pharmacokinetic models of various types. Simple pharmacokinetic models are used here to describe general relationships valid for large groups of chemicals or situations. Important parameters to consider are the half-life of the biological indicator, the individual variability and the exposure variability. Biological sampling strategies are presented for monitoring of groups of workers, or individual workers. For specific chemicals, mainly solvents, more elaborate models can be developed, i.e., physiologically-based pharmacokinetic models including physiological, metabolic and physicochemical parameters. Such models are useful to describe the influence of confounding factors. Physiologically-based pharmacokinetic models can also be developed for metals and metalloids. Antimony is presented here as an example. In conclusion, pharmacokinetic modeling brings much information on sampling time, sample size, limit values, effect of physical workload and of individual physiological parameters.

Antimony↗
PubMed1986

Medical screening and biological monitoring for the effects of exposure in the workplace. Screening and monitoring: tools for prevention.

The mission of the National Institute for Occupational Safety and Health (NIOSH) is the prevention of work-related diseases and injuries. Medical screening and biological monitoring are recognized as important tools of prevention; however, the number of complex and sophisticated tests available has created new problems of choice in this field. Many of these tests have no relevance to preventing work-related diseases or injuries. To provide important guidelines in this area, NIOSH has identified the ten leading work-related diseases and injuries (Table 1). Several of these medical screening and biological monitoring techniques can be applied as tools for prevention. Within this framework, achieving the goal of preventing work-related diseases and injuries can be enhanced by collecting, analyzing, and interpreting information about occupational health problems.

Accidents, Occupational↗
PubMedDate not supplied

[Measurements and environmental and biological monitoring of occupational exposure to inhalation anesthetics].

This paper reports the data of nitrous oxide (N2O) environmental pollution in 269 operating rooms of 47 hospitals in Italy in 1989-91. In 40% of the operating rooms the N2O concentrations are lower than 50 ppm, limit value proposed by Health Council for new operating rooms. In 65.4% of the operating room studied, N2O mean environmental concentrations are lower than 100 ppm, value proposed by the above-mentioned Health Council as limit value for the already existing operating rooms. Concerning the biological monitoring, the authors report several N2O data in urine (2193), whose levels confirm the data obtained with environmental monitoring. The authors believe that they presently have reliable methods to perform biological and environmental monitoring: the two techniques are complementary in the assessment of the exposure. The method of measuring N2O concentrations as exposure index, both for the environmental and biological monitoring, is considered very useful to simplify the performance of the analyses. In order to assess exposure more precisely, it is however necessary also to determine the environmental and/or biological measure of the other different anaesthetics used.

Air Pollutants, Occupational↗
PubMed1993

Biological monitoring of occupational pesticides exposure.

Two kinds of measurement: (1) enzyme activities in blood, and (2) unchanged pesticides and their metabolites in urine or blood have been used in biological monitoring for assessing exposure to pesticides. The assays of acetylcholinesterase (AChE) activity in whole blood and erythrocytes are mainly applied to estimate inhibition by organophosphates (OPs) and carbamates. A level at 70% of an individual's baseline or of a mean population AChE activity has been recommended as a reference value for exposure control. The measurement of lymphocyte "neuropathy target esterase (NTE)" activity in subjects handling axonopathic OPs is mainly for research application. Analytical methods are available for detecting alkylphosphates, carbamates, pyrethroids, chlorinated hydrocarbons, some herbicides and fungicides, chlordimeform, chlorobenzilate, dichloropropene, dinitrocresol and pentochlorophenol or their metabolites in urine or blood. However, due to lack of significant dose-response or dose-effect relationship, the majority of these determinants can only be used as biological exposure indicators to confirm exposure or to estimate internal dose. Further research in developing adequate indicators and methods for biological monitoring of occupational pesticides exposure is needed. Pre-exposure value and/or reference value of relevant indicators are necessary for assessing the degree of exposure and absorption.

Environmental Monitoring↗
PubMed2003

Biological monitoring of workers after the application of insecticidal pyrethroids.

OBJECTIVES: Pyrethroids are applied as insecticides throughout the world. Human metabolism of pyrethroids results in urinary metabolites that are suitable for biological monitoring. The aim of the study was to evaluate individual exposure due to occupational application of pyrethroids as a precondition for the assessment of health risks. METHODS: Thirty-six workers who applied insecticides and other pesticides in Germany collected samples of their urine (24 h) after having used various pyrethroids (alpha-cypermethrin, cypermethrin, cyfluthrin, deltamethrin, tau-fluvalinate, permethrin, lambda-cyhalothrin) in agriculture, greenhouses or indoor pest control. Biological monitoring was carried out and metabolites were analysed in 61 urine samples by GC-MS: cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid ( cis-Cl(2)CA and trans-Cl(2)CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid ( cis-Br(2)CA), 3-phenoxybenzoic acid (3-PBA) and 4-fluoro-3-phenoxybenzoic acid (FPBA). Forty-five urine specimens collected (24 h) from persons with no occupational exposure to pyrethroids served as controls. Concentrations were related to creatinine content and expressed as microgrammes per gramme creatinine. RESULTS: Control urine samples revealed a considerable background excretion of pyrethroid metabolites by the general population. The 95th percentile of the concentrations of Cl(2)CA and cis-Br(2)CA were 2.1 and 0.1 microg/g creatinine, respectively. FPBA was not detected in any control urine and was found in only one sample within the complete study. After occupational application of pyrethroids the highest concentrations of metabolites in urine samples were detected within the group of indoor pest-control operators. The maximum concentrations (median values) of Cl(2)CA, 3-PBA, and cis-Br(2)CA were 92.4 microg/g (1.8 microg/g), 57.5 microg/g (1.4 microg/g) and 1.1 microg/g (median below detection limit), respectively. Workers in greenhouses excreted metabolites with median concentrations as follows: 2.9 microg/g Cl(2)CA, 0.5 microg/g cis-Br(2)CA and 2.9 microg/g 3-PBA. Medians of the metabolite concentrations in specimens from agricultural workers were below the detection limit with regard to Cl(2)CA and cis-Br(2)CA, but the value was 0.6 microg/g for 3-PBA. Pest-control operators excreted significantly higher concentrations of Cl(2)CA and 3-PBA than workers in agriculture on a collective basis. Comparison of the excreted concentrations of metabolites with values of acceptable daily intake (ADI) of pyrethroids set by WHO revealed that the amount of pyrethroids that had been taken up during occupational application was not considerably higher than the ADI. CONCLUSIONS: As a consequence, we conclude that adverse health effects are not to be expected after workers' occupational exposure to pyrethroids in Germany, provided that the application is carried out properly. Good working practices need to be supported by adequate supervision with regard to occupational hygiene and medicine.

Agriculture↗
PubMed1987

Occupational chronic exposure to metals. I. Chromium exposure of stainless steel welders--biological monitoring.

External and internal chromate exposure of 103 stainless steel welders who were using manual metal are welding (MMA), metal inert gas welding (MIG) and both methods, were measured by ambient and biological monitoring. At the working places the maximum chromium trioxide concentrations were 80 micrograms/m3. The median values were 4 micrograms/m3 (MMA) and 10 micrograms/m3 (MIG). The median chromium concentrations in erythrocytes, plasma and urine of all welders were less than 0.60, 9.00 and 32.50 micrograms/l. For biological monitoring purposes, chromium levels in erythrocytes and simultaneously in plasma seem to be suitable parameters. According to our results, chromium levels in plasma and urine in the order of 10 and 40 micrograms/l seem to correspond to an external exposure of 100 micrograms chromium trioxide per cubic metre, the technical guiding concentration (TRK-value). Chromium concentrations in erythrocytes greater than 0.60 micrograms/l indicate an external chromate exposure greater than the TRK-value.

Adult↗
PubMedDate not supplied

[Biological monitoring of environmental benzene exposure in traffic wardens].

Vehicle exhausts are a well known source of aromatic hydrocarbon pollution in urban environments. The paper reports the results of environmental and biological monitoring of benzene exposure in traffic wardens carried out over a 5-hour workshift. Subjects (n = 131) were grouped according to smoking habits and job task as follows: group (A) 52 nonsmoking office workers, (B) 43 nonsmoking outdoor workers, subdivided into (B1) 36 working on foot and (B2) 7 cyclists; (C) 20 smokers office workers, (D) 16 smokers outdoor workers, subdivided into (D1) 11 working on foot and (D1) 5 cyclists. The median indoor environmental benzene concentration (26 micrograms/m3, n = 50) was significantly lower than the outdoor concentration (45 micrograms/m3, n = 43) (p < 0.01); median exposure value of cyclists was 78 micrograms/m3 (n = 12). For biological monitoring, urinary excretion of trans,transmuconic acid was determined in spot samples collected at 7:30 h (MAit) and 12:30 h (MAft). The MAftA median value (63 micrograms/l, range 2-242 micrograms/l) was not statistically different from MAftB (74 micrograms/l, range 15-216 micrograms/l), while the MAftB2 value of 96 micrograms/l was higher than both MAftB1 (71 micrograms/l) and MAftA. In group (B) there was a relationship between airborne benzene levels and MAftB excretion (y = 17.2 + 1.1x, r = 0.62, n = 35, p < 0.01). The influence of smoking on urinary MA excretion was studied by comparing the results obtained in all nonsmokers (AB) with smokers (CD). MAftCD (192 micrograms/l) was significantly higher than MAftAB (69 micrograms/l) (p < 0.01). In smokers, statistically significant relationships were observed between urinary excretion of MAft (y, microgram/l) and cotinine (x, microgram/l) (y = 83 + 0.08x, r = 0.73, n = 23, p < 0.01), and smoking (x, number cigarettes/day) (y = 87.4 + 4.4x, r = 0.53, n = 29, p < 0.01). Comparison between MAft and MAit median excretion values, calculated for each of the 6 exposure groups, showed that MAft was always higher than the corresponding MAit value. A rough estimate of the total dose of benzene ("index of exposure", EI) inhaled by each subject during the 5-hour working shift as a consequence of air pollution and smoking was also made. Considering the entire group of subjects, a significant association was observed between EI and MAft values (y = 43.4 + 0.39x, r = 0.65, n = 104, p < 0.01). Individual values of MA it were correlated with MAft according to the equation y = 43.6 + 0.82x (r = 0.62, n = 105; p < 0.01) and were also positively associated with EI values (y = 42.3 + 0.20x; r = 0.55; n = 74; p < 0.01). In conclusion, the results suggest that the measurement of urinary MA excretion is a poor indicator for assessing environmental benzene exposure at levels below 100 micrograms/m3, such as those seen in this study; MA can however be reliably used as a biomarker for higher exposures such as those, for example, due to smoking.

Adult↗
PubMed2001

The effects of contamination on biological monitoring.

We investigated the frequency and patterns of biological-monitoring-test contamination and the effect of contamination on the growth of test organisms. Overall, the contamination rate was 0.81%, but the rate of contamination varied significantly by sterilization method. Contamination did not appear to inhibit growth of test organisms.

Bacillus subtilis↗
PubMed2004

Biologic monitoring for urinary uranium in gulf war I veterans.

Biologic monitoring for total uranium in urine of Gulf War I veterans concerned about past exposure to depleted uranium (DU) has been offered by the Departments of Veterans Affairs and Defense since the late 1990's. DU, a component of U.S. munitions and tank armor, was first used during that conflict. Two hundred and twenty-seven veterans submitted samples for analysis from January 2000 through December 2002, which included a 24-h urine sample for determination of total urinary uranium concentration and completed questionnaires describing their wartime exposure experiences. Thirty questionnaire items characterizing DU exposure opportunities were collapsed into 19 exposure categories. Urine uranium (U) results were stratified into low and high uranium groups with 0.05 microg U g creatinine as the cut point. Exposure scenarios in the high and low uranium groups were similar in frequency and type with only the presence of retained shrapnel being predictive of a high urine uranium value, as found in the first phase of this surveillance of 169 veterans performed prior to 2000. Twenty-two veterans exhibited U levels in the high range. Isotopic analysis, available for 21 of these 22, revealed that all but three of these samples contained natural and not depleted uranium. These three participants had retained DU shrapnel as a result of their past injuries. Thus, even with an enlarged cohort, elevated urine uranium values in the absence of retained DU fragments are unlikely. The utility of isotopic analysis to more fully characterize uranium biomonitoring results is also demonstrated.

Body Burden↗
PubMed1993

Effect of various exposure scenarios on the biological monitoring of organic solvents in alveolar air. I. Toluene and m-xylene.

The present study was undertaken to investigate the influence of different exposure scenarios on the elimination of toluene and m-xylene in alveolar air and other biological fluids in human volunteers. The study was also aimed at establishing the effectiveness of physiologically based toxicokinetic models in predicting the value of biological monitoring data after exposure to toluene and m-xylene. Two adult male and two adult female white volunteers were exposed by inhalation, in a dynamic, controlled-environment exposure chamber, to various concentrations of toluene (21-66 ppm) or m-xylene (25-50 ppm) in order to establish the influence of exposure concentration, duration of exposure, variation of concentration within day, and work load on respective biological exposure indices. The concentrations of unchanged solvents in end-exhaled air and in blood as well as the urinary excretion of hippuric acid and m-methyl-hippuric acid were determined. The results show that doubling the exposure concentration for both solvents led to a proportional increase in the concentrations of unchanged solvents in alveolar air and blood at the end of a 7-h exposure period. Cumulative urinary excretion of the respective metabolites exhibited a nearly proportional increase. Adjustment of exposure concentration to account for a prolongation of the duration of exposure resulted in essentially identical cumulative urinary excretion of the metabolites. Induced within-day variations in the exposure concentration led to corresponding but not proportional changes in alveolar concentration for both solvents, depending on whether or not sampling preceded or followed peak exposure to solvent. At the end of repeated 10-min periods of physical exercise at 50 W, alveolar air concentrations of both solvents were increased by 40%. Experimental data collected during the present study were adequately simulated by physiologically based toxicokinetic modeling. These results suggest that alveolar air solvent concentration is a reliable index of exposure to both toluene and m-xylene under various experimental exposure scenarios. For clinical situations likely to be encountered in the workplace, physiologically based toxicokinetic modeling appears to be a useful tool both for developing strategies of biological monitoring of exposure to volatile organic solvents and for predicting alveolar air concentrations under a given set of exposure conditions.

Adult↗