The environmental risk assessment of chemicals is significantly impeded by the complexity of environmental systems. In particular, the detection and prediction of certain effects caused by chronic low-level exposure or effects on population or ecosystem levels is difficult and methodologically controversial. Here, a modified approach is presented which is to assess the chemicals separately with respect to exposure (first step) and effects (second step). To this end, persistence and spatial range are introduced as two purely exposure-based endpoints. With a simple model of the global circulation, persistence and spatial range are determined for various chemicals, in particular for Persistent Organic Pollutants (POPs). According to the precautionary principle, long-range and persistent compounds are identified as chemicals of particular concern the use of which should be avoided. An outlook on the possible implications of this approach for the regulation of chemicals is given.