Abstract
A group of people in a printing works who were occupationally exposed to toluene (n=94) was used to investigate the relationship between the toluene concentration in the air, the toluene level in the blood and the hippuric acid excretion in the urine. The toluene analyses in the air and in the blood were carried out using gas chromatography, and the hippuric acid determinations were carried out using spectrophotometry. The upper normal limit of the toluene concentration in the blood (calculated from a control group not exposed to solvents; n=30) was found to be 15 μg toluene per 100 ml blood. In the exposed test subjects, a close relationship was found between the toluene concentration in the blood and that in the air, while a dependency of the hippuric acid excretion in the urine on the toluene concentration in the blood or in the air could not be statistically confirmed. However, phenol determinations in urine that were carried out at the same time showed a highly significant correlation with the excretion of hippuric acid in the urine of the subjects exposed to toluene. This calls into question the suitability of phenol determinations in urine for monitoring people exposed to benzene while also being exposed to toluene. In addition to the determination of hippuric acid in urine, a toluene analysis in the blood is recommended as a criterion for individual exposure for monitoring people exposed to toluene.
