Biological monitoring of exposure to styrene by analysis of combined urinary mandelic and phenylglyoxylic acids.

Human volunteers were exposed in an experimental chamber to styrene (4 or 8 hours at 40 to 200 ppm) in order to obtain a quantitative relationship between exposure and urinary elimination of the metabolites mandelic and phenylglyoxylic acids (MA and PGA). For the analysis of PGA a new GC-method was used, based on reductive transformation of the relatively instable PGA into MA, which is stable enough for shipping and handling until final processing. The analysis of the post-exposure elimination shows that spot urine sampled in the morning after exposure and analysed for the sum of MA and PGA is the most reliable index for reflecing a preceding exposure to styrene.