Urinary mandelic acid as an exposure test for ethylbenzene.

Absorption of ethylbenzene and excretion of mandelic acid were investigated under controlled conditions in six volunteers, exposed at concentrations of 18, 34, 80, and 200 mg/m3. Retention of ethylbenzene vapours in the lungs was 49 +/- 5%. Elimination of mandelic acid was found to be biphasic, with biological half-life values of 3.1 and 24.5 h. Total excreted mandelic acid accounts for 55 +/- 2% of retained ethylbenzene. The results obtained were applied to devise an exposure test for ethylbenzene, which would enable the precise evaluation of exposure at low ethylbenzene, vapour concentrations (+/- 13%). Exposures, carried out dermally, gave a rationale for the exclusion of the skin as a route of entry of ethylbenzene vapours into the body.