Improvement of the AMI method [Assessment of the Median Impact] for the assessment of toxic stress on ecosystems in LCA

The AMI method [Assessment of the Median Impact] facilitates the assessment of impacts on ecosystems in LCA [Life Cycle Assessment] while taking into account different levels of diversity: the diversity of the chemicals (an LCA commonly consists of more than 300 chemicals) and the diversity of ecosystems, which can vary in terms of complexity and the robustness of the species. The AMI method is based on the median response of ecotoxic tests for multiple species. Aquatic toxicity characterisation factors and associated uncertainty are calculated for more than 400 chemicals using data from OPP99 and ECETOC. The level of uncertainty is related to the number of species tested. It is demonstrated that this approach can yield a reliable result with a high level of discrimination between substances. The relevance of toxicity assessment can be improved by the inclusion of chronic data. Such data can be used in the AMI method when data for at least four species are available. In the absence of chronic data, assessment based on acute toxicity data, including calculation of the uncertainty, is necessary. This requires identification of the origin of the variability in the ecotoxic results, considering key parameters like: chemical, species, endpoint (Lethal Concen-tration/ Effect Concentration or No Observed Effect Concentration), type of effect (lethality, growth, reproduction . . .) and test duration. The results of the associated analysis are based on data from 15000 tests and underline the importance of the number of data to reduce the uncertainty interval.