Evaluation of exposure to mixed solvents by analysis of urinary metabolites and solvents: content ranges.

To evaluate worker's exposure to mixed solvents, equations for the calculation of the biological hazard index, which is defined as biological levels tolerable for exposure to mixture, were developed. When biological levels of exposure indicators were not affected by coexposure, rules similar to those for airborne monitoring could be applied. Namely, when the components had additive effects, the biological hazard index was calculated from the concentration of urinary metabolites or parent solvents, by an equation which was essentially similar to the equation for the calculation of the hazard index. In the present study, the confidence limits of the biological hazard index and predictive limits for individual specimens were calculated. These equations could be used under the condition that the uptake, metabolism and elimination of solvents were practically unaffected by coexposure. When urinary metabolites or solvents of some components of a mixed solvent alone were determined and those of the remaining components were not determined, the concentration of urinary metabolites or solvents of remaining components were estimated from the airborne concentration of the other components.