1,721,003 research outputs found
Identification of the metabolites of n-hexane, cyclohexane, and their isomers in men's urine
No full textThe main metabolites of n-hexane, cyclohexane, 2-methylpentane and 3-methylpentane were detected in urine samples obtained from workers exposed in shoe factories
N-N-dimethylformamide concentration in environmental and alveolar air in an artificial leather factory
No full textN-N-Dimethylformamide was determined every hour during the eight hours of the work shift in the alveolar air of eight workers employed in an artificial leather factory and in the breathing zone of the eight workers. The alveolar ventilation of each worker was measured for 10 minutes during the work shift. Alveolar dimethylformamide concentration (Ca) was correlated with the environmental concentration (Ci) in six of the eight workers. The amount of dimethylformamide retained per litre of ventilated air, calculated as the difference (Ci - Ca), was correlated with environmental concentration in seven of the eight workers. Lung uptake of dimethylformamide per minute was correlated with environmental concentration in all eight workers. The ratios between alveolar and environmental concentration (Ca/Ci x 100) and the lung retention of dimethylformamide, calculated by the formula (1 - Ca/Ci) x 100, were 27.8% and 72.2% respectively. They did not show any correlation with environmental concentration, exposure time, or alveolar ventilation
Urinary excretion of the metabolites of n-hexane and its isomers during occupational exposure
No full textEnvironmental exposure to commercial hexane (n-hexane, 2-methylpentane, and 3-methylpentane) was tested in several work places in five shoe factories by taking three grap-air samples during the afternoon shift. Individual exposure ranges were 32-500 mg/m3 for n-hexane, 11-250 mg/m3 for 2-methylpentane, and 10-204 mg/m3 for 3-methylpentane. The metabolites of commercial hexane in the urine of 41 workers were measured at the end of the work shift. 2-Hexanol, 2,5-hexanedione, 2,5-dimethylfuran, and gamma-valerolactone were found as n-hexane metabolites and 2-methyl-2-pentanol and 3-methyl-2-pentanol as 2-methylpentane and 3-methylpentane metabolites. The presence of metabolites in the urine was correlated with occupational exposure to solvents. n-Hexane exposure was correlated more positively with 2-hexanol and 2,5-hexanedione than with 2,5-dimethylfuran and gamma-valerolactone. A good correlation was also found between total n-hexane metabolites and n-hexane exposure. 2-Methyl-2-pentanol and 3-methyl-2-pentanol were highly correlated with 2-methylpentane and 3-methylpentane exposure. The results suggest that the urinary excretion of hexane metabolites may be used for monitoring occupational exposure to n-hexane and its isomers
Neurotoxic metabolites of "commercial hexane" in the urine of shoe factory workers
No full textUrinary metabolites were tested in 41 shoe-factory workers exposed to a mixture of 10 solvents among which "commercial hexane" was the prevailing component. Cyclohexanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, and trichloroethanol were determined in connection with exposure to cyclohexane, 2-methylpentane, 3-methylpentane, and trichloroethylene, respectively. 2-Hexanol, 2,5-hexanedione, 2,5-dimethylfuran, and gamma-valerolactone were all determined in connection with n-hexane exposure only. 2,5-Hexanedione was the principal n-hexane metabolite found in the workers' urine. This finding of the experimentally proven neurotoxin 2,5-hexanedione in the urine of shoe-factory workers exposed to "commercial hexane" is consistent with the idea that this compound is responsible for the development of neuropathy in this group of individuals
Solvent exposure in a shoe upper factory- 1. n-Hexane and acetone concentration in alveolar and environmental air and in blood
No full textAcetone and n-Hexane concentrations were determined in the environmental air of a shoe upper factory and in the alveolar air and venous blood of the workers employed. The ratio between alveolar and environmental n-hexane concentration (Ca/Ci) was found to be steady during the 4.5 hours of exposure studied, and independent of alveolar ventilation and n-hexane environmental concentration. Lung uptake per minute was correlated with environmental concentration. In the case of acetone the Ca/Ci ratio was found to increase with exposure time, but to be independent of alveolar ventilation and environmental acetone concentration. A correlation was still found between lung uptake and environmental acetone concentration. The correlation found between Ca and Ci suggests the hypothesis that occupational exposure can be studied by testing the alveolar air concentration of individual exposed workers in the case of hexane. Since in the case of acetone the Ca/Ci ratio increases with exposure time, it is necessary to know the time of exposure in order to estimate environmental exposure from alveolar acetone concentration. Blood concentration was correlated with environmental and alveolar concentration in the case of hexane, correlated with alveolar concentration in the case of acetone. © 1978 Springer-Verla
Urinary excretion of n-hexane metabolites in rats and humans
No full textExposure to n-hexane, a component of many industrial solvent mixtures, is known to cause polyneuropathy in man. The concentration of metabolites in urine following exposure may be useful in biological monitoring. In a comparative study experimental animals (rat, rabbit and monkey) were subjected to single inhalatory treatments of 6, 12 and 24 h with 5,000 ppm of pure n-hexane. At the end of the treatments and at intervals thereafter, urine, and in rats also blood, were collected and analyzed for n-hexane and its metabolites. While the urine of rats contained 2-hexanol, 3-hexanol, methyl n-butyl ketone, 2,5-dimethylfuran, y-valerolactone and 2,5-hexanedione, rabbit and monkey urine were found to contain only 2-hexanedione, rabbit and monkey urine were to contain only 2-hexanol, 3-hexanol, methyl n-butyl ketone and 2,5-hexanedione. Within 72 h of the end of exposure, the principal metabolite was 2,5-dimethylfuran in rats and 2-hexanol in rabbits and monkeys. In all three species the excretion rates of methyl n-butyl ketone, 3-hexanol and 2-hexanol peaked several hours earlier than 2,5-hexanedione (and gamma-valerolactone and 2,5-dimethylfuran in rats). In all species 2,5-hexanedione was still detectable in urine 60 h following exposure. n-Hexane metabolites in rat blood were 2-hexanol, methyl-n-butyl ketone, 2,5-dimethylfuran and 2,4-hexanedione. The first two, as well as n-hexane itself, were found in maximum concentration immediately after termination of exposure, while 2,5-dimethylfuran and 2,5-hexanedione, with the longer exposure times, peaked some hours later. The data from urine collected at the end of exposure were compared with those obtained in a parallel study in humans occupationally exposed to a mixture of hexane isomers. Humans chronically exposed to 10-140 ppm n-hexane had 2,5-hexanedione concentrations in urine ranging from 0.4 to 21.7 mg/l, i.e., in the same proportion as rats exposed once for 6 or 12 h to 5,000 ppm
Decline of blood and alveolar toluene concentration following two accidental human poisonings
No full textIn two workers admitted to hospital because of a coma due to an accidental occupational exposure to a mixture of solvents, the level of toluene was respectively 823-1122 micrograms/l in the blood and 53-38 micrograms/l in the alveolar air on the second day of admission (36 h after the accidental exposure). On the fifth day, 112 h after exposure, the toluene level was 120-45 micrograms/l in the blood and 3-1 micrograms/l in the alveolar air. The urinary excretion of o-cresol, calculated as a toluene equivalent, was 0.8-0.9 mg on the second day and 1.7-1.6 mg on the third day. Urinary hippuric acid, as a toluene equivalent, was 1.7-1.4 g on the second day and 1.3-0.7 g on the third day. A half-life of between 19 and 21 h was calculated for toluene both in the blood and in the alveolar air
Toluene concentrations in the blood and alveolar air of workers during the workshift and the morning after
No full textOccupational toluene exposure was studied during the workshift and the morning after by the analysis of environmental air, alveolar air, and blood. Environmental toluene exposure was measured by both continuous and instantaneous sampling. Instantaneous environmental toluene concentrations correlated better with alveolar toluene concentrations (r = 0.94; n = 155) than with blood toluene concentrations (r = 0.71; n = 52). Continuous environmental toluene concentrations correlated better with blood toluene concentrations (r = 0.84; n = 65) than with alveolar toluene concentrations (r = 0.52; n = 46). During the workshift and the morning after, blood and alveolar toluene concentrations correlated significantly with each other (r = 0.75; n = 66 and r = 0.67; n = 52). In a group of workers who were exposed to a mean environmental toluene concentration of 146 micromilligrams the concentrations of toluene in the alveolar air and blood the morning after were 3.2 micromilligrams (SD = 1.7) and 27.5 micromilligrams (SD = 12.7) respectively. With regard to the morning after toluene determinations, blood concentrations correlated (r = 0.52; n = 52; p less than 0.001) better than the alveolar concentrations with the corresponding afternoon values (r = 0.36; n = 52; p less than 0.01). The decline of the toluene concentrations from the end of one workshift to the start of the next exposure indicated a mean toluene half life of 3.8 hours in the alveolar air and of 4.5 hours in blood and therefore the 17 hour interval between two consecutive workshifts was insufficient for the complete elimination of absorbed toluene
Physiologicomathematical model for studying human exposure to organic solvents: kinetics of blood/tissue n-hexane concentrations and of 2,5-hexanedione in urine
No full textThe physiologicomathematical model with eight compartments described allows the simulation of the absorbtion, distribution, biotransformation, excretion of an organic solvent, and the kinetics of its metabolites. The usual compartments of the human organism (vessel rich group, muscle group, and fat group) are integrated with the lungs, the metabolising tissues, and three other compartments dealing with the metabolic kinetics (biotransformation, water, and urinary compartments). The findings obtained by mathematical simulation of exposure to n-hexane were compared with data previously reported. The concentrations of n-hexane in alveolar air and in venous blood described both in experimental and occupational exposures provided a substantial validation for the data obtained by mathematical simulation. The results of the urinary excretion of 2,5-hexanedione given by the model were in good agreement with data already reported. The simulation of an exposure to n-hexane repeated five days a week suggested that the solvent accumulates in the fat tissue. The half life of n-hexane in fat tissue equalled 64 hours. The kinetics of 2,5-hexanedione resulting from the model suggest that occupational exposure results in the presence of large amounts of 2,5-hexanedione in the body for the whole working week
Partition coefficients of some industrial aliphatic hydrocarbons (C5-C7) in blood and human tissues
No full textSaline/air, blood/air, olive oil/air, and tissue/air (lung, kidney, liver, brain, muscle, heart, and fat) partition coefficients were determined for nine aliphatic hydrocarbons: n-pentane, 2,2-dimethylbutane, 3-methylpentane, 2-methylpentane, methylcyclopentane, n-hexane, cyclohexane, 3-methylhexane, and n-heptane. Blood/air partition coefficients were found to range between 0.38 (n-pentane) and 1.9 (n-heptane) and the value of the tissue/air partition coefficients rose from n-pentane to n-heptane. The tissue/air partition coefficients were significantly correlated with the blood/air partition coefficients (r = 0.92-0.98). According to the slope of the regression lines, the mean solubility of the nine aliphatic hydrocarbons in the different tissues was higher than in blood by the factors: lung 1.4 (range 1.2-2.1) heart 3.9 (range 0.5-4.5), liver 5.6 (range 5.5-13.5), kidney 5.2 (range 1.6-5.8), brain 6.5 (range 5.8-10.7), muscle 7.6 (range 1.8-8.8), and fat 205 (range 104-254). The blood/air and olive oil/air partition coefficients were significantly correlated with the boiling points and the molecular weights of the aliphatic hydrocarbons studied
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