Richtwerte für Toluol und gesundheitliche Bewertung von C7-C8-Alkylbenzolen in der Innenraumluft : Mitteilung des Ausschusses für Innenraumrichtwerte.

The German Committee on Indoor Guide Values issues indoor air guide values to protect public health. For health evaluation of inhaled toluene a number of valid studies in humans is available. Toluene is a neurotoxic substance and the guide values are based on deficits in neurobehavioural tests observed at workers with chronic exposure of 337 mg toluene/m³. For the derivation of guide values the assumed continuous exposure is considered by a factor of 4.2, the interindividual variability by a factor of 10 and the elevated respiratory rate in children as compared to adults by a factor of 2. The resulting health hazard guide value (guide value II) is 4 mg toluene/m³. As the difference to the former indoor air guide value of 1996 for toluene is only caused by the slightly changed extrapolation factor for continuous exposure, the committee maintains the guide value II of 3 mg toluene/m³ and the precautionary guide value (guide value I) of 0.3 mg toluene/m³ indoor air. As all C7-C8 alkylbenzenes are neurotoxic the committee evaluates toluene, ethylbenzene and the xylenes as a group. In order to achieve a total evaluation the ratios of concentration and respective guide value of each compound were added. The total guide values I and II are regarded to be complied with if the corresponding sum falls below 1.