HUMAN EXPOSURE TO STYRENE .3. ELIMINATION KINETICS OF URINARY MANDELIC AND PHENYLGLYOXYLIC ACIDS AFTER SINGLE EXPERIMENTAL EXPOSURE

To obtain the necessary information on the elimination kinetics of the main urinary metabolites in humans after styrene exposure (mandelic (MA) and phenylglyoxylic acids (PGA)), which is required in order to develop a biomonitoring program suitable for industrial exposure situations, human experimental exposures were carried out at concentrations of 50 to 200 ppm and durations of 4 to 8h, limiting the total exposure to 800 ppm.h (TWA at the TLV). MA analysis in urine was performed by silylation and gas chromatography. PGA was reduced to MA prior to analysis as previously described. The post exposure elimination of MA and PGA was found to follow biphasic kinetics, the elimination of PGA being slower than that of MA (MA: t1/2 at 0-20 h = 3.9 h, at 30-60 h = 24.7 h; PGA: t1/2 at 0-50 h = 10.5 h). The correlation of the urinary elimination of MA and PGA with exposure was studied at different post exposure times in order to select the sampling period suited best for biological exposure monitoring. The product balance of uptake and elimination confirmed that in contrast to the situation in animals, only an insignificant amount of styrene is metabolized to hippuric acid in humans. The discussion of the data obtained in this study with regard to the toxicity of styrene showed the need for epidemiological field studies using simultaneous air, biological, and medical monitoring. At present, such a study is being carried out in the polyester plastic industry. © 1979 Springer-Verlag.