The concept of biomonitoring comprises the one-off or repeated systemic measurement of concentrations of hazardous substances and their metabolites in biological materials. If the materials are from a human biological source, the concept of human-biomonitoring is usual. In contrast to determining exposure to the human environment (e.g. air quality, food contamination), biomonitoring has the advantage of reflecting the actual, individual exposure of a human organism (e.g. in the form of biomarker). This enables an individual health risk concerning systemic effects to be better described than by solely measuring exposure.

Benzene and toluene are volatile organic compounds (VOC). Their ubiquity means they are found in all indoor air. Due to their toxic potential (benzene—carcinogenic, toluene—neurotoxic) and the quantities in which toluene is found, sometimes actual exposure to toluene must be measured.

One way is to test urine for specific metabolites to monitor the internal burden and dosage. S-phenyl- and S-benzylmercapturic acid (SPMA and SBMA) were selected and their concentrations determined in urine samples from Leipzig children. The results were correlated with the benzene and toluene concentrations of indoor air. Whereas a correlation was found between benzene and SPMA, no connection was established between toluene and SBMA. One of the next targets is to find a correlation between the measuring results and information concerning ailments given in response to questionnaires on the children’s health.