PARENT SESSION

5B a - RA/ Ranking and Chemical Specific
Poster Hall
8:30 AM - Tuesday, 29 April 2003
Chair: Loonen, H.¹, ¹
Co-chair: McCarty, L.², ²

(TUP/196) Comparative Risk Assessment of Products.

Becker-Van Slooten, Kristin¹, Payet, Jerome², ¹ CECOTOX-ENAC Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland² GECOS-ENAC Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

ABSTRACT- Current methods in Environmental Risk Assessment (ERA) are based on the assessment of a safety level for the use of chemicals, and generally aim to be conservative. Such methods, based on the Predictive No Effect Concentration (PNEC) or the Hazardous Concentration for 5% of species (HC5), do not offer good discriminating power between the toxicity of substances nor an accurate assessment of the uncertainty. However, more and more studies comparing toxicological impact of substitutable products are now published (e.g.: deicers, antifouling, fungicides, etc), whilst no methods are available for the comparative risk assessment of products. Indeed, the objective in comparative assessment is to achieve best estimates. The main parameters influencing the final results are linked to the choice of the ecotoxicological parameters (No Observed Effect Concentration, Effect Concentration) and the endpoint (reproduction, lethality). Furthermore, the importance of the chosen mathematical models is analyzed comparing parametric and non-parametric models for the uncertainty assessment. An innovative method adapted for Comparative Risk Assessment of Products based on all the species tested will be presented. The main methodological problems like time and temporal scale or threshold calculation will be outlined, illustrated with a case study on comparative assessment of products. Focusing on the variability of the ecotoxicological indicator, the results underline the strength of an indicator based on the standard error on the geometric mean or the median (using bootstrap) compared to an indicator based on the most sensitive species. Furthermore, an assessment using non-parametric methods appears to be more accurate than parametric ones, with respect to the asymmetry of the distribution.

Key words: Aquatic ecotoxicology, Comoparative Risk Assessment, Terrestrial ecotoxicology, non parametric estimator