The urinary hippuric acid of workers exposed to the low level and multiple organic solvents

Urinary hippuric acid is a widely used BEI (Biological Exposure Index) for workers exposed to toluene, and it is recommended to use the marker based on population who expose to toluene concentration over 50 ppm. To evaluate the reliability of hippuric acid as a bioindicator for toluene concentration in work-place below 50 ppm accompanied with other solvents exposure, 96 subjects, including 41 subjects in exposure group and 55 subjects in non- exposure group, were examined. Results indicate that urinary hippuric acid is significantly different between exposure group and non-exposure group. Under this condition, we recommend that using hippuric acid as a bioindicator for toluene exposure should base on group observation and elucidation. It shows that the U.S. NISOH recommended BEI value (2.5g/g Cr.) of hippuric acid for toluene exposure worker also meets the requirement of workers, who expose to 100ppm of toluene, of the Republic of China.