Metabolism of ethylbenzene in the rat during long-term intermittent inhalation exposure

After exposure of rats to atmospheres of 50, 300 or 600 p.p.m. ethylbenzene six hours/day, five days/week, for a max. of 16 weeks, the concn. of ethylbenzene in perirenal fat and the urinary excretion of 1-phenylethanol, omega-hydroxyacetophenone, mandelic, phenylglyoxylic, hippuric and phenaceturic acids were measured at the second, fifth and ninth weeks. Excretion of metabolites into urine increased in a dose-related manner, but less than linearly. The level of exposure, but not the duration of exposure, markedly affected the pattern of the metabolites in the urine. The concn. of ethylbenzene in perirenal fat was low at 50 p.p.m., high at 300 p.p.m. and higher still at 600 p.p.m., but not in proportion to the increased dose.