correlation between toluene environmental monitoring and biological index of urinary hippuric acid of workers in the coke industry

introduction: toluene is an organic solvent that it is one of the byproducts in the coke industry. exposure to toluene causes central nervous system dysfunction and others disorders. many workers are exposed to toluene due to leakage from tracks. therefore the aim of this study was to determine the levels of exposure through environmental and biological monitoring of toluene methods: air toluene sampling of air inhaled by 36 coke oven workers was done by using activated charcoal tubes and personal sampling pumps. at the end of the shift, urine samples of workers and control group were collected by urine samplers. air toluene was determined by gc, urinary hippuric acid by hplc and urine creatinine level was determined by auto analyzer. results: the mean of air toluene and urinary hippuric acid levels in exposed and control samples were 14.34 ppm, 0.33 and 0.28 g/g creatinine. air toluene and urinary hippuric acid showed a correlation of r = 0.8. conclusion: toluene twa was lower than the tlv-twa (p=0.000). urinary hippuric acid concentration was also lower than the bei (p=0.008). difference between exposed and unexposed group was not significant. this study showed that hippuric acid because of its interaction with background factors can not be used as a sensitive biomarker for biomonitoring.