Abstract
To evaluate the intensity of worker exposures to mixed solvents, the concentrations of hippuric acid (HA), methylhippuric acids (MHAs), and methyl isobutyl ketone in end-of-shift urine were examined in male workers who had been simultaneously exposed to 15.2 ppm toluene, 13.9 ppm xylenes, and 16.7 ppm methyl isobutyl ketone for 8 hours. Regression equations were calculated between the intensity of the exposure of each solvent to which workers were simultaneously exposed and the urinary concentration of the metabolites or a solvent corresponding to the solvent to which they were exposed. These equations were then compared with the corresponding regression equations of three groups of workers, each of which was exposed to only one of the solvents. The results of the exposure to a low concentration of the solvent indicated that each component had a minimal pharmacokinetic effect on the concentrations of urinary excretions from other solvents. The hazard index (k) and biological hazard index (kB) values for mixed exposure were calculated to be 0.619 and 0.64, respectively. The findings of this study also indicate that the biological hazard index for mixed exposures can be used to evaluate body exposure of workers exposed to relatively low amounts of these mixed solvents.
