“…Solvent workers: This group were artisans, who had been engaged in making sandal, shoe, and leather at small factories using solvent mixtures containing mainly n-hexane, xylene, and toluene. Concentrations of metabolites of solvents in urine samples taken from the workers in the morning before work for 2,5-hexanedione (HD), methylhippuric acid (MHA), and hippuric acid (HA) ( Table 1) were higher than those of male Japanese without solvent exposure, i.e., 0.25 ± 0.23 mg/g Creatinine (Cn) for HD, 0.028 ± 0.021 g/g Cn for MHA, and 0.14 ± 0.71 g/g Cn for HA, respectively (mean ± SD) 29,30) . 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) .…”