In fact, ACGIH [26] recommended using O-cresal in
urine as biomarker for exposure to toluene, instead of using
hippuric acid as a biomarker of exposure. In Thailand,
however, there have been limitations regarding analytic
technologies, thus hippuric acid has been more favored as
a biomarker of exposure. Most importantly, no food with
a preserving agent should be taken before the test (benzoic
acid) [37].