Kira, S; Ogata, M; Horii, S; Ebara, Y; Otsuki, S; Kawai, T; Yasugi, T
A study of urinary excretion of cresols and methanol (67561) in a solvent sniffer who inhaled a solvent containing toluene (108883) and methanol was conducted. Serial urine samples were collected from a 32 year old male hospitalized twice for inhaling a paint thinner that contained toluene and methanol. The estimated concentrations of toluene and methanol that he inhaled were 3067 and 12,350 parts per million, respectively. The patient did not experience any visual disturbances or show any evidence of optical nerve changes, common sequelae of methanol poisoning. The urine samples were analyzed for hippuric-acid (495692), o-cresol (95487), m-cresol (108394), p-cresol (106445), and methanol. The maximum excretion rates of hippuric-acid, o-cresol, m-cresol, p-cresol, and methanol after the first hospitalization were 23.7 milligrams (mg) per minute (min) and 15.3, 11.6, 199.5, and 226.7 micrograms (microg)/min, respectively. The corresponding estimated biological halflives were 730, 690, 787, 1956, and 350min. The maximum excretion rates of hippuric-acid, o-cresol, m-cresol, p-cresol, and methanol after the second hospitalization were 12.7mg/min and 11.9, 3.7, 75.5, and 183.7microg/min, respectively. The corresponding halflives were 704, 623, 887, 912, and 318min. Regression equations were developed for the excretion of o-cresol as a function of hippuric-acid excretion in the early stages of end/exposure. The equations underestimated o-cresol excretion during the first 180min after exposure. The authors suggest that the prolonged elevated concentrations of urinary o-cresol may reflect a metabolic interaction between toluene and methanol or reduced elimination of hippuric-acid mediated by toluene.