Combined Effects of Chemicals: An Essential Element in Risk Extrapolation for Aquatic Ecosystems

Abstract

Joint toxic action of compounds in aquatic ecosystems is a factor that should be taken into consideration when environmental quality criteria are derived from the outcomes of toxicological tests in the laboratory. Many risk-extrapolation procedures calculate so-called ‘safe' environmental criteria for single compounds, regardless of possible interactions. However, additivity of toxic effects of different compounds, even at very low concentrations has been demonstrated by many different researchers. The possibility to integrate the aspect of joint toxic action into risk-extrapolation protocols is discussed against the background of the available scientific evidence.