RESUMO
BACKGROUND: Benzoic acid contained in some food can hinder the biological monitoring of hippuric acid in urine, which is frequently used as an exposure index of toluene and xylene. METHOD: 20 male examinees who are not exposed to organic solvents in their jobs were given a bottle of drink containing benzoic acid(70 mg/dl) and took it. Urine samples were taken from every person just before, in 1.5 hrs after, and in 3 hrs after taking the drink. Hippuric acid in urine was analyzed with improved Ogata and Taguchi method and creatinine with Jaffe method. RESULT: Mean hippuric acid concentrations in urine just before, in 1.5 hrs after, and in 3 hrs after taking the drink were 0.59+/-0.21 g/g creatinine, 2.75+/-0.98 g/g creatinine, 1.04+/-0.58 g/g creatinine, respectively. And, each group had statistically significant differences (p<0.01). There were no statistically significant differences between two groups categorized by age, smoking, and drinking. CONCLUSION: From the results, we suggest that when hippuric acid concentration in urine is used as a exposure index of toluene, it should be surveyed whether the food containing benzoic acid was taken or not.