Exposure to toluene increases the urinary excretion of D-glucaric acid

Workers at a printing plant exposed to low concentrations of toluene (43-401 mg/m3, median 155 mg/m3) had increased urinary D-glucaric acid (3.55-5.12 mmol/mol creatinine) excretion at the end of the shift compared with controls (2.45-3.35 mmol/mol creatinine). No increase was found after the summer holiday (1.92-2.89 mmol/mol creatinine) but excretion had increased two weeks later (4.05-5.55 mmol/mol creatinine). These changes in the excretion of D-glucaric acid were not correlated to levels of exposure, to changes of urinary hippuric acid and o-cresol half lives (three to eight hours), nor to o-cresol/hippuric acid concentration ratios when measured at the end of daily exposure. Since a significant intra and interindividual variability of urinary D-glucaric acid was found in all groups, urinary D-glucaric acid excretion is suitable to monitor group but not individual exposure.