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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 42 (1978), S. 91-103 
    ISSN: 1432-1246
    Keywords: Toluene ; Absorption ; Elimination ; Workload ; Biological monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six healthy male subjects exposed to various concentrations of toluene in inspired air (50, 100, and 150 ppm) under controlled conditions of rest or physical exercise, showed markedly little differences in the rate of respiratory solvent uptake. On the whole the intra-individual variations proved as important as the between subjects variations. For a given level of physical exercise the lung clearance appeared most affected by fluctuations in respiratory minute volume. In our experimental group the uptake rate was not significantly influenced by the amount of body fat. Toluene concentrations in expired air (CE) during the first 4 h after an exposure cannot be considered a reliable measure for the individual toluene uptake. This parameter appears to reflect the influence of a number of host factors which do not affect — or at least not in the same way — the toluene uptake by itself. As a consequence the observed variability of toluene in the expired air was always much greater than for the related lung clearances. The single most important factors explaining differences in respiratory solvent excretion, were the respiratory minute volume in the post-exposure period and, after exposures at rest, the amount of body fat. The mean excretion amounted to about 4 % of the total uptake within 24 H after the end of the exposure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 44 (1979), S. 99-107 
    ISSN: 1432-1246
    Keywords: Toluene ; Urinary hippuric acid ; Energetical load ; Aliphatic hydrocarbons ; Heliorotagravure printing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of a number of factors possibly affecting the relation between urinary hippuric acid excretion and the exposure level to toluene was studied in a population of heliorotagravure printers. It was observed that the hippuric acid excretion rates, after 4 h and 8 h from the onset of the exposure, were in better agreement with the average toluene concentrations in work room air than either the urinary metabolite concentrations alone or corrected for urine density. Apart from differences in exposure level, a substantial proportion of the interindividual variability in hippuric acid excretion could be explained by differences in energetical load during the exposure. It was thereby not possible to elucidate the full extent to which this factor influences the metabolite excretion. In good agreement with previous experimental findings, the hippuric acid excretion rate apparently does not depend on the time of urine sampling during the exposure, provided that at least 4 h have elapsed from the onset.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 61 (1989), S. 243-247 
    ISSN: 1432-1246
    Keywords: Ethylene glycol monomethyl ether ; Respiratory uptake ; Human exposure ; Methoxyacetic acid ; Urinary excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The uptake of EGME and the urinary excretion of its major metabolite (MAA) was studied in seven male volunteers during experimental exposure to EGME at rest. The exposure concentration was set at 16 mg/m3, the present Threshold Limit Value. A high retention (0.76) remained unchanged during the 4-h exposure period. In combination with a constant pulmonary ventilation and a fixed exposure concentration this resulted in an uptake rate that showed no significant variation in time. The total amount of EGME inhaled corresponded to a dose of only 0.25 mg/kg. During and up to 120h after the start of the exposure, MAA was detected in the urine. The elimination half-life was on average 77.1 h. The total amount of MAA excreted was calculated by extrapolation and averaged 85.5% of the inhaled EGME. The pharmacokinetic data are compared with those obtained from other human exposure studies to ethylene glycol ethers (EGEE and EGBE).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 43 (1979), S. 53-62 
    ISSN: 1432-1246
    Keywords: Toluene ; Urinary hippuric acid ; Experimental exposure ; Work load ; Biological monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between the individual toluene uptake and the urinary hippuric acid excretion was studied under experimental conditions. Six healthy male subjects were exposed to various concentrations in inspired air (50, 100, 125, 150, and 200 ppm) at rest or under different levels of physical effort. The hippuric acid excretion near the end of the exposure appeared under all circumstances directly proportional to the time-weighted uptake rate of toluene. The correlation between respiratory uptake rate and the rate of metabolite excretion near the end of the exposure period proved not to be systematically influenced by personal factors such as body weight, amount of body fat, urine flow rate and urinary pH. The relatively pronounced differences in background excretion of hippuric acid and, perhaps, distribution phenomena of toluene between different tissues under heavy workload conditions, can partly explain the greater variability in metabolite excretions as compared to the individual uptake rates. The correlation between the individual uptake rate of toluene and the hippuric acid excretion proved substantially better when using the end exposure excretion rate as exposure parameter as compared with the end exposure hippuric acid concentration, even after correcting the latter for urine density. Reasonable biological limit values complying to an acceptable time-weighted toluene dose were found to be 3000–3500 mg/l and 2.0–2.5 mg/min, resp. for average hippuric acid concentrations and excretion rates in spot samples during the second half of a complete work shift.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 61 (1989), S. 249-254 
    ISSN: 1432-1246
    Keywords: Ethylene glycol ethers ; Alkoxyacetic acids ; Pentafluorobenzylbromide ; Gas chromatography ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A sensitive and specific method for the determination in urine of alkoxyacetic acids, the metabolites of ethylene glycol monoalkyl ethers, was developed by combining the advantages of two previously described methods. The acids were determined gas chromatographically as their pentafluorobenzylesters. The alkylation with pentafluorobenzylbromide was performed after dissolving the dry residue of lyophilized urine in methanol. Quantitative derivatization was obtained when the urinary pH was adjusted to pH 7.0, when the reagent concentration was 5% v/v, and when the reaction mixture was heated at 90°C for 3 h. Sample clean-up was performed by adding bidistilled water and the esters were extracted with methylene chloride with high yields (95%). Alkoxyacetic acid concentrations in the range of 0.1 to 200 mg/l could be determined with an average imprecision of ± 3.5%.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 59 (1987), S. 243-250 
    ISSN: 1432-1246
    Keywords: Carbon disulfide ; 2-Thiothiazolidine-4-carboxylic acid (TTCA) ; Experimental exposure ; Respiratory uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six human volunteers were exposed to 10 and 20 ppm carbon disulfide at rest and to 3 and 10 ppm carbon disulfide under a 50 W level of physical exercise during four consecutive periods of 50 min. At the start of the experiments, at the end of the exposure periods and during the post-exposure period, urine was sampled and the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) was determined. It was established that only a small percentage, ranging from 0.7 to 2.2% of the absorbed carbon sulfide was transformed into TTCA. The excretion rate of TTCA (μmol TTCA h−1) was found to be the best parameter in evaluating the respiratory uptake of carbon disulfide over a range of 37.9 to 163.3 mg CS2 compared to the urinary concentration of TTCA (mole TTCA ml−1) or the creatinine corrected concentration of TTCA (mmol TTCA mol−1 creatinine). The total amount of TTCA (μmol TTCA) excreted proved to be independent of the urinary flow (ml h−1), the estimates of the individual fatty tissue content and the urinary pH. No correlation was found between the respiratory uptake of carbon disulfide (mg CS2) and the excretion rate of TTCA within each exposure condition of 3, 10 or 20 ppm carbon disulfide, respectively.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 59 (1987), S. 233-242 
    ISSN: 1432-1246
    Keywords: Experimental exposure ; Carbon disulfide ; Respiratory uptake ; Respiratory elimination ; Workload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six human volunteers were exposed to 10 and 20 ppm carbon disulfide at rest and to 3 and 10 ppm carbon disulfide under a 50 W level of physical exercise during four consecutive periods of 50 min. Every 5 min a sample was taken from the mixed exhaled air in which the concentration of carbon disulfide was determined. It was established that only an apparent steady state was reached during this exposure period. The retention values were established as 0.374 (SD = 0.106; n = 239) for exposure to 10 ppm carbon disulfide at rest and as 0.410 (SD = 0.103; n = 239) for exposure to 20 ppm carbon disulfide at rest. During exposure to 10 ppm and 3 ppm carbon disulfide, combined with a 50 W level of physical exercise, the retention values decreased to 0.286 (SD = 0.083; n = 239) and 0.277 (SD = 0.049; n = 239) respectively. Thereby, the measured individual retention values of carbon disulfide show considerable interindividual differences. The respiratory uptake of carbon disulfide (mg CS2) proved significantly influenced by the amount of body fat estimated from skinfold thickness measurements. The respiratory elimination of carbon disulfide in the exhaled air can be described by means of a two-exponential decay.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 49 (1982), S. 251-263 
    ISSN: 1432-1246
    Keywords: n-Hexane ; Experimental exposure ; Respiratory absorption ; Respiratory elimination ; Venous blood ; Workload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The respiratory uptake rate of n-hexane showed considerable differences in six healthy male persons, exposed at rest to 360 mg/m3 and 720 mg/m3 of n-hexane in inspired air and to 360 mg/m3 under different levels of physical exercise. These differences could partly be explained by a positive correlation with the amount of body fat. At rest also a strong influence of the respiratory minute volume and respiratory frequency on the uptake rate could be proven. The average uptake rate remained virtually constant over a range of 20 to 60 W of continuous external physical load, indicating that under these circumstances the inspired n-hexane concentration alone predominantly determines the uptake rate. The respiratory elimination during the first hours after an exposure was also subject to important inter- and intraindividual fluctuations. The pulmonary ventilation rate at the moment of breath sampling had a pronounced influence on the measured exhaled concentration. On the other hand, there was no apparent effect of the amount of body fat. Generally, the correlation between the amount of n-hexane taken up and breath concentrations at different time intervals was rather poor. n-Hexane concentrations in peripheral venous blood reacted rapidly to changes in exposure conditions, but not in the same proportion as the uptake rate. The blood concentration proved more closely related to respiratory n-hexane retention than to the uptake rate, reflecting the state of saturation of different body tissues. At rest this parameter was clearly influenced by the amount of body fat. A decrease in relative blood perfusion of fatty tissue could explain why such relation was not found during exposure combined with physical effort.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 42 (1978), S. 105-117 
    ISSN: 1432-1246
    Keywords: Toluene ; Venous blood ; Experimental exposure ; Workload ; Biological monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The application as biologic exposure parameter of the toluene concentration in venous blood during and after an exposure to this solvent was experimentally studied. Under carefully controlled conditions 6 healthy male subjects were exposed to various concentrations of toluene in inspired air (50, 100, 125, 150 and 200 ppm) at rest or under different levels of physical effort. Peripheral venous concentrations (Cv) were followed in relation to the individual toluene uptake. A relatively constant relation was found between uptake rate of toluene and Cv under steady state conditions. Empirically, for lung clearances at rest and for differing inspired concentrations (CI), this relation was given by: Cv (mg/l) = 0.303 CI (mg/1) x Lung clearance (1/min). Under constant CI (50 ppm) and lung clearances varying from rest values to values under a continuous exercise of 50 W, the regression equation became: Cv (mg/l) = 0.328 CI (mg/l) x Lung clearance (1/min). Under non-steady state conditions no simple relation existed between uptake rate and Cv, indicating that equally no simple connection could be made between Cv and the calculated mixed venous concentration, or, extrapolating, the expected toxic load of most inner organs. In relation to the individual dose, Cv always presented a much greater variability than the toluene uptake by itself. The observed differences, both intra-individually as between subjects, were mostly statistically significant. Apparently Cv was influenced by some host factors in another manner than the uptake rate. In this respect evidence was obtained that the local blood perfusion and the amount body fat were involved to a certain extent. For this reason Cv proved a somewhat less satisfactory individual dose-parameter.
    Type of Medium: Electronic Resource
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