Life cycle impact assessment (LCIA) and comparative risk assessment (RA) use the same building blocks for analyzing fate and potential effects of toxic substances. It is tacitly assumed that emission-effect calculations can give uniform and decisive answers in debates on toxicity problems. For several decades, mainstream policy sciences have taken a different starting point when analyzing decision making on complex, controversial societal issues. Such controversies in essence are thought to be caused by the fact that different actor coalitions adhere to a different, but in scientific terms equally reasonable, conceptualization or "framing" of the problem. A historical, argumentative analysis of the Dutch chlorine debate and the Swedish PVC debate shows that this is also true in the discussions on toxic substances. Three frames have been identified, which were coined the "risk assessment frame," "the strict control frame," and the "precautionary frame." These frames tacitly disagree about the extent of knowledge/ignorance about the impacts of substances, the robustness/fallibility of emission-reduction schemes, and the robustness/vulnerability of nature. The latter frame, adhered to by environmentalists, seeks to judge substances mainly on their inherent safety. Under the current institutional arrangements and practices, RA and LCIA are executed mainly in line with the philosophy expressed by the risk assessment frame. This article gives various suggestions for dealing with framing in debates on toxic substances. One of the options is elaborated in somewhat more detail, i.e., the development of multiple indicators and calculation schemes for RA and LCIA that reflect the different frames. An outline is given for a possible indicator system reflecting the precautionary principle.