Derivation of risk-based guide value for vinyl chloride in indoor air. Communication from the German Committee on Indoor Air Guide Values (AIR)

In the European Hazardous Substances Regulation No 1272/2008 vinyl chloride has been classified as known human carcinogen (Carc.1 A). Based on two large epidemiological studies with similar data, the German MAK-Commission derived a linear exposure-risk relationship (ERR) between incidences of angiosarcomas in the liver and cumulative exposure of vinyl chloride. This ERR was adopted by the Committee on Hazardous Substances and also the basis of the quantitative risk assessment of the German Committee on Indoor Air Guide Values. After extrapolation to lifelong continuous exposure by a factor of 5.7 and applying an extra factor of 2 for the more sensible children, this results in a concentration of 2.3 mu g/m(3) vinyl chloride for a life-time risk of 10(-6). A reference value, the 95th percentile of indoor air concentrations is not available. However, several single measurements near contaminated places indicate that an indoor air concentration above the risk-based guide value is not probable.