Ecologically acceptable concentrations when assessing the environmental risks,of pesticides under European Directive 91/414/EEC

Pesticides are authorized in the European Union under Directive 91/414/EEC. This is a two-stage process that involves EU-wide assessment for Annex I listing followed by individual Member State assessment. Recently the concept of an Ecologically Acceptable Concentration (EAC) has been used during both stages of environmental risk assessments. The EAC is a concentration at which no unacceptable ecological effects occur and has been interpreted as a concentration at which acceptable effects may be allowed to occur. This article reviews the implications of the EAC concept for pesticides risk assessment and proposes improvements to make its use more objective.