The main products of styrene biotransformation excreted in human urine are mandelic and phenylglyoxylic acids. Phenylethylene oxide seems to be the first metabolite; this compound has been reported to be mutagenic and carcinogenic. The polarographic determination of mandelic acid has been used for about 20 years in Czechoslovakia as an exposure test for persons occupationally exposed to styrene. Only single cases of health damage have been reported to be due to styrene exposure during this time. Recently, however, elevated frequencies of chromosomal aberrations in peripheral lymphocytes have been observed in persons exposed to styrene in Czechoslovakia. The amount of phenylethylene oxide that can be formed in the human body during exposure to 50 ppm of styrene in air during a workshift is about 0.7 g. It would be hardly justifiable now to believe that styrene is not carcinogenic and mutagenic in man. The present Czechoslovakian maximum allowable concentration of styrene (200 mg/m³) should be reduced, and the concentration of 50 mg/m³ may be recommended as reasonable at this time. The corresponding biological limit value of mandelic acid might be 300 mg/l of urine from the last 2 h of the workshift.

Key terms evaluation; exposure test; hazard; industry; mandelic acid; metabolism; phenylglyoxylic acid; styrene; styrene oxide