[Occupational medicine limit values for hazardous materials in the Federal Republic of Germany].

In all industrial countries ambient air quality guides for working materials are introduced serving the objective of protecting health in groups of workers, if exposure takes place solely or predominantly by way of inhaling noxious substances. Individually there may be, however, a lot of marginal conditions modifying atmospheric dose-response relationships. Therefore today in many countries biological monitoring became an additional approach in the prevention of occupational health risks. In this connection in the Federal Republic of Germany a second safety-barrier Biological Tolerance Values for Working Materials (BAT-values) were established. For carcinogenic substances, however, scientifically well founded health protection criteria cannot be established. But, from practical point of view, certain biological quality guides should be useful for carcinogenic substances too, especially for skin penetrating compounds. This was the background to establish Equivalents of Exposure for Carcinogenic Compounds, standing for correlations between the concentration of a carcinogen in the air of the workplace and the concentration of the agent or its metabolites in biological material, resulting from mere inhalation. Substance concentrations in biological materials being higher than predicted from concentration in the air of the workplace are suspicious of an additional skin absorption. For risk assessment, from industrial-hygienic point of view, it is a good approach to quantify the exposure by air monitoring. From clinical point of view it is a better one to exclude adverse effects by biological monitoring. For prevention of health risks it is the best way to do both.