[Health evaluation of indoor air carcinogens: first addendum to the basic scheme. Communication from the German Committee on Indoor Guidelines].

According to the German Committee on Indoor Guidelines valid data on the usual occurrence of a carcinogenic substance in indoor air (e. g. the 95(th) percentile or reference value) and its exposure-risk relationship must be available for health evaluation. Depending on the mechanism of action of the substance the Committee decides which dose-response relationship is appropriate.Given a valid exposure-risk relationship the concentration of an indoor air carcinogen associated with a theoretical cancer risk of 10(-6) following lifetime exposure has to be estimated. The obtained concentration has to be compared to its reference value.If the concentration obtained from the exposure-risk relationship exceeds the reference value, it will be used as a risk-related guideline. If the concentration of the reference value is associated with a cancer risk above 10(-6), the reference value will be used as preliminary guideline.