BIOLOGICAL MONITORING OF STYRENE EXPOSURE AND POSSIBLE INTERFERENCE OF ACETONE COEXPOSURE

The object of this study is the evaluation of some of the toxicokineti c effects of exposure to low concentrations of styrene, and the possib le influence of simultaneous exposure to acetone. To this end we studi ed 19 workmen simultaneously exposed to both solvents. During a week o f 4-h work shifts, the workmen underwent daily personal environmental monitoring and the collection of urine samples, at both the beginning and the end of the work period, for the determination of mandelic acid (MA) and phenylglyoxylic acid (PGA). The presence of the solvents in the atmosphere was evaluated using passive personal monitoring and gas chromatography. Average exposure to styrene and acetone were respecti vely 72.2 mg/m(3) and 225.7 mg/m(3). MA and PGA were quantified by hig h-performance liquid chromatography (HPLC). The daily urinary concentr ation averages, both at commencement and at the end of work shifts, of both the metabolites studied and of the sum of the two, were in stati stically significant linear correlation with the average daily styrene exposure. Concentrations of MA and PGA in urine samples collected at the start of the work shift averaged 61.5 mg/g creatinine and 45.2 mg/ g creatinine respectively: representing 41% and 72% of those at the en d of the work shift which were 148.3 and 62.6 mg/g creatinine, respect ively. With equal exposure to styrene, the average urinary concentrati ons of MA and PGA at both the beginning and end of the work shift incr eased significantly (P < 0.001) during the working week. Moreover, we found that with equal exposure to styrene, urinary excretion of MA, PG A and MA + PGA at the end of the shift was inversely correlated with t he intensity of acetone exposure (r = 0.4659, 0.3410 and 0.4542 respec tively, P < 0.001). In conclusion, these results express slower urinar y kinetics of styrene metabolites than is usually described in the lit erature, and favor a tendency to accumulate MA and PGA in the organism as a consequence of the retardation of urinary excretion kinetics. Ac etone apparently represents one of the determining factors in this int erference.