The Determination of Trans, Trans-Muconic Acid in Urine as an Indicator of Occupational Exposure to Benzene

Abstract

Recently the determination of muconic acid (MA; milligrams/gram creatinine) in urine has been proposed as a suitable biomarker for the monitoring of low level exposure to benzene. A sample of 171 subjects employed in a factory was studied for personal exposure to benzene [CI, benzene (parts per million)] and excretion of AM. The 8-hour time-weighted exposure intensity of individual workers was monitored by means of charcoal tubes. MA excretion level in urine was determined by high performance liquid chromatography with ultraviolet detection. The following linear correlation was found between MA concentrations in urine and benzene concentrations in the breathing zone log MA(mg/g creatinine) = 0.549 log CI, benzene (ppm) – 0.18 (n = 171, r = 0.614, p < 0.0001) MA concentrations in urine from 100 nonexposed subjects (50 smokers >20 cigarettes/day and 50 nonsmokers) were also determined [geometric mean of 0.207 mg/g creatinine (1.5) and 0.067 mg/g creatinine (2.1), respectively]. In the current study, the levels of MA in smokers were about three times higher than those in nonsmokers. The study results indicate that the urinary level of MA can be regarded as a useful indicator of occupational exposure to benzene.