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(M/MF199) Comparison of acute: chronic ratios for chemicals using the EAT 3 database. Tencalla, F.1, Eadsforth, C.2, Holt, M.3, Lemaire, P.4, Roman, G.5, Wierich, P.6, Worden, J.7, 1 2 3 4 5 6 7 ABSTRACT- For many new and existing chemicals, only a limited amount of toxicity data is available. When conducting the risk assessment of these compounds for the aquatic environment, current regulations define assessment factors. Application of these factors to the lowest aquatic data available for a given chemical allows to extrapolate a "safe level" at which no adverse effects are expected for the aquatic environment. Assessment factors have been assigned to cover species to species, species to ecosystem and acute to chronic extrapolations. Based on the first ECETOC aquatic toxicity database (EAT), an earlier Task Force analysed acute EC50 : chronic NOEC ratios for selected substances and concluded that currently used assessment factors were overly conservative. The EAT database has now been expanded to include 5460 data points on almost 600 chemicals. With the information from the new database (EAT 3), acute to chronic ratio (ACR) calculations were repeated and the results compared to those obtained earlier. Further investigations were carried out, looking specifically at ACR for standard aquatic test species. Also, ACR were calculated for different chemical classes, including organic and inorganic compounds, metals and pesticides. The new results are largely in accordance with earlier findings. Although the spread of the ACR values is wider due to the enlargement of the database, 95th-percentile values remain well below a factor of 1000, especially when taxonomic groups or chemical classes are evaluated separately. Even when all data is pooled, more than 50% of the ACR remain within a factor 10 (0.1 - 10), with less than 10% above 100. Key words: ecotoxicity data, acute, chronic, comparison |
