GM-troph: A Low Data Demand Ecotoxicity Effect Indicator for Use in LCIA (13+3 pp)

• Published in: The international journal of life cycle assessment 2007-03, Vol.12 (2), p.79-91
• Main Author: Hauschild, Michael
• Format: Article
• Language: English
• Subjects: Algae; Consumers; Crustacea; Crustaceans; data collection; ecosystems; ecotoxicology; fish; Invertebrates; laboratory techniques; Laboratory tests; life cycle impact assessment; Studies; Taxa; Toxic substances; Toxicity; Trophic levels; trophic relationships
• ISSN: 0948-3349; 1614-7502
• DOI: 10.1065/lca2006.12.288

GOAL, SCOPE AND BACKGROUND: The development of ecotoxicity effect indicators (EEIs) for use in life cycle impact assessment (LCIA) has only been going on for about two decades. Traditionally, no-effect indicators have been applied. In this paper we focus on the development of an effect-based (i.e. EC50-based) average indicator, the GM-troph. The indicator is estimated by use of the hazardous concentration for 50% of the covered species (HC50EC50) and is designed to work on a low substance data availability of only three acute data values, which is often required in LCIA. METHODS: The study includes a theoretical description and a test on real data of three different effect-based average approaches (arithmetic mean, geometric mean and median) focusing on their statistical robustness. The data set used for the testing is composed of real ecotoxicity effect data for eleven different substances representing seven different toxic modes of action (TMoA). RESULTS AND DISCUSSION: The theoretical considerations and the test on real data show that the geometric mean is the most robust average estimator for HC50EC50, especially in the frequent situation where data availability is limited to a few data points. Test results indicate that in some cases of unequal representation of the different taxa (or trophic levels) in the underlying data set, estimations of average toxicity (i.e. HC50EC50) may be biased if each single test data (at a species level) is used as data points instead of averages at trophic levels. CONCLUSIONS: and Recommendations. Based on these results, the following recommendations are given for the choice of estimation principle for the EEI: The indicator shall be based on HC50EC50 estimated as the geometric mean of three (average) EC50 values, covering the three main taxa, plants, invertebrates and vertebrates, which represent the three trophic levels of the ecosystem, primary producers, primary consumers and secondary consumers. In practice, the EEI shall be based on data from laboratory tests with algae, invertebrates (crustaceans) and fish. Instead of using the often wide 95% confidence limits, it is recommended to use the range given by the observed maximum and minimum values as limits around the HC50EC50. Further, it is recommended to use EC50(chronic) values when possible. Often, only acute data will be available, and here the use of best estimate assessment factors is recommended to extrapolate from acute to chronic values. As a starting point