n-Hexane metabolism in occupationally exposed workers.

Abstract

ABSTRACr Lung uptake and excretion of n-hexane were studied in ten workers in a shoe factory. Simultaneous samples of inhaled and alveolar air were collected with the aid of a Rhan-Otis valve, personal samplers, and charcoal tubes. Alveolar excretion was monitored during a six hour postexposure period. Uptake was calculated from lung ventilation, the retention coefficient, and environmental concentrations. The amount of exhaled n-hexane was calculated from the decay curve. According to the experimental data, alveolar retention was about 25% of the inhaled n-hexane, corresponding to a lung uptake of about 17%. The postexposure alveolar excretion was about 10% of the total uptake. The main metabolites of n-hexane were identified and measured by capillary GC/MS in spot urine samples collected before, at the end, and 15 hours after the same working shift. Urinary concentrations were low, though related to n-hexane in the air. 2,5-Hexanedione in the end of shift samples gave the best estimate of overall exposure. About 3 mg/g creatinine of 2,5-hexanedione would correspond to about 50 ppm of n-hexane in the air (mean daily exposure).The use of n-hexane is widespread in industry. It is an excellent and inexpensive solvent used especially in glues, varnishes, and paints. Many mixtures are commercially available, and the most common among them contain different proportions of n-hexane and its isomers 2-methyl and 3-methyl pentane, cyclohexane, and methyl ethyl ketone. Occupational exposures have been reported to cause peripheral neuropathies in workers'-3; electrophysiological changes have also been found in subjects exposed to relatively low airborne concentrations. 48 The pharmacokinetics of n-hexane has been widely investigated in rats but much less is known for man. Among the published studies there is little agreement about the retention of inhaled n-hexane and about the proportion which is excreted through the lung during the postexposure period. the metabolism of n-hexane in man, with the aim of evaluating more specifically: (a) the respiratory uptake and elimination in workers occupationally exposed under constant model ventilation conditions; (b) the possible relation between n-hexane uptake and urinary excretion of its metabolites; and (c) the usefulness of either alveolar concentration or urinary excretion of n-hexane metabolites for biological monitoring purposes. MethodThe study was performed on 10 young healthy , and the flow rate 1 ml helium per minute. Particular interest was focused on the following metabolites: 2 and 3-hexanol, 2,5-hexanediol, methyl n-butyl ketone, 2,5 hexanedione, y-valerolactone, and 2,5-dimethylfuran. Authentic samples of each substance were obtained from Fluka AG (Buchs, Switzerland). The urinary metabolites were identified on the basis of gas chromatographic retention time, and their mass spectra were compared with those of authentic samples, using a Finnigan MAT 1020 mass spectrometer (Finnigan MAT, Cincinnati, OH, USA). EQUATIONSIntake, uptake, and alveolar excretion were calc...

n‐Hexane [BAT Value Documentation, 1994]

“…With greatly fluctuating exposure concentrations (45 -405 ppm n-hexane) an average retention rate of 15 % was determined for workers of a shoe factory (10). This value was confirmed by further investigations (46,82). After the end of exposure a large amount of the n-hexane at first retained is exhaled again unchanged (50).…”

Postural Sway Frequency Analysis in Workers Exposed ton-Hexane, Xylene, and Toluene: Assessment of Subclinical Cerebellar Dysfunction

“…As urinary samples were taken approximately 16 hr after the end of last shift (17:00) and the half-life of urinary excretion of HD is 13-14 hr (IPCS, 1991), HD in end-of-shift urine of workers was estimated to be at least twice that in the samples examined, i.e., about 0.8-6 (mean, 2.4) mg/g Cn. These values may correspond to 13-100 (mean 40) ppm of n-hexane in air during work, as it has been reported that 3 mg/g Cn of HD in end-ofshift urine is equivalent to 50 ppm of n-hexane in air (Mutti et al, 1984).…”

Computerized Posturography with Sway Frequency Analysis: Application in Occupational and Environmental Health.

“…HD in end-of-shift urine of workers was estimated to be at least twice that in the samples examined, i.e., about 0.8-6 (mean 2.4) mg/g Cn, as urinary samples were taken approximately 16 hr after the end of last shift (17:00) and the half-life of urinary excretion of HD is 13-14 hr 31) . These values may correspond to 13-100 (mean 40) ppm of n-hexane in air during work, as it has been reported that 3 mg/g Cn of HD in end-of-shift urine is equivalent to 50 ppm of n-hexane in air 32) . Similarly, MHA concentrations in urine of the workers at the end of shift were estimated at approximately 5-19 folds of those in the morning urine, i.e.…”