Evaluation of hippuric,phenylglyoxylic and mandelic acids in urine as indices of styrene exposure

Summary In addition to those of phenylglyoxylic and mandelic acids, a distinct increase in hippuric acid level was observed in the urine of factory workers who were exposed to styrene at 50 to 200 ppm for 160 min. Comparison of the postexposure levels with respective non-exposure levels and supplements with rat exposure experiments revealed hippuric acid to be a poor indicator of styrene exposure at a moderate degree, while the other two acids are much more adequate indices. At a higher dose of styrene (e.g., 500 mg/kg i.p. or 100 ppm for 8 hrs for rats), however, the urinary levels of phenylglyoxylic and mandelic acids reach plateaus, while hippuric acid level remained proportional to the amount of styrene given.The biological half-life of styrene in human subjects is approximately 8 hrs as measured by the disappearance of phenylglyoxylic and mandelic acids from urine.This work was supported in part by a grant from the Fujiwara Memorial Foundation