Determination of S-phenylmercapturic acid in urine as an indicator of exposure to benzene

S-phenylmercapturic acid (S-PMA) was measured in urine from 145 subjects ex posed to low benzene concentrations in the air (C-I, benzene). The 8-h, tim e-weighted exposure intensity of individual workers was monitored by means of charcoal tubes and subsequent gas-chromatographic analysis after desorpt ion with CS2. S-PMA excretion level in urine was determined by high-perform ance liquid chromatography with fluorescence detection. The following linea r correlation was found between S-PMA concentrations in urine and benzene c oncentrations in the breathing zone: log(S-PMA, mu g/g creatinine) = 0.712 log (C-I-benzene, ppm) + 1.644 (n = 145, r = 0.74, P < 0.001). The geometri c mean (GSD) of S-PMA concentrations in urine from 45 subjects occupational ly not exposed to benzene but smoking more than 20 cigarettes/day was 7.8 m u g/g creatinine (2.11), the corresponding value among non-smokers being 1. 0 mu g/g creatinine (2.18). It is concluded that the urinary level of S-PMA can be regarded as a useful indicator of exposure to benzene. (C) 1999 Pub lished by Elsevier Science Ireland Ltd. AU rights reserved.