The German Chemicals Act stipulates that certain existing chemicals must be reported to the competent authority, if they exhibit properties which indicate they may be hazardous, either alone or in combination with other chemicals (§ 4 (6) ChemG). In summer 1982, an Advisory Committee on Existing Chemicals of Environmental Relevance (BUA), consisting of representatives from science, chemical industry, and governmental authorities, was established at the Society of German Chemists (GDCh). Its purpose was to seek appropriate solutions for dealing with chemicals which are relevant to health and the environment through the adoption of voluntary measures. It is the responsibility of this committee to selected and examine existing chemicals for environmental or health purposes as authorized by § 4 (6) ChemG. In doing so, exclusively scientific criteria are to be applied. In view of the estimated number of about 100000 chemicals in the inventory of existing chemicals of the European Community (EINECS), a selection on the basis of strictly quantitative criteria is not feasible. Even if the necessary resources were available, reliable data for a quantitative evaluation are lacking in most cases. Consequently, a pragmatic approach had to be developed for carrying out a selection on the basis of the limited data available. For this purpose, chemicals were compiled from various priority lists: the presence of these chemicals in the environment has been proved or is highly probable; they are industrially important, or are manufactured in large quantities. Approximately 4500 substances were compiled in this manner. From this total, about 1000 chemicals were selected on the basis of their occurrence in the environment and their industrial significance. After elimination of those substances which are subject to special legal regulations, materials of natural origin, inorganic chemicals, and chemicals which are unstable in the environment, a remainder of 512 chemicals was obtained. For these chemicals data were collected in respect to eight selection criteria covering environmental exposure and effects. For selection purposes these data were scored (scoring procedure). This approach resulted in a list of 60 substances which may be of environmental relevance and which consequently should be treated with priority. In continuation with this work the Advisory Committee now presents a second list of 75 chemicals which are environmentally relevant. The production volume of these chemicals served as an additional criterion. This second selection is, again, associated with considerable uncertainty, since the data employed are partially incomplete, and because their scientific quality could not be checked individually in all cases. This means that, analogously to the chemicals of the first list, this list may also include chemicals which are not hazardous to the environment, and on the other hand, some environmentally hazardous substances may have been omitted. Again, a conclusive evaluation is not feasible until all available data have been collected in separate substance reports and possibly lacking data have been obtained by means of appropriate testing.