Is it relevant to take into account the multipollution context in freshwater radioecology?

J. Garnier-Laplace, A. Boudou, C. Adam, B. Fraysse, 0. Ausseil, J.M. Porcher J.P. Baudin and C. Casellas Actes du congrès ECORAD, 3-7 sept 2001, Aix en Provence, France Radioprotection - Colloques, volume 37, C1-185 / C1-190.

Should realism of radioecological evaluations be enhanced while taking into, account the deleterious influence of stable pollutants on aquatic organisms which can be physiologically stressed, and therefore can modify their response to radionuclide bioaccumulation? Transfer experiments in a multipollution context involved metals (Cd, Zn), organic pollutants (PCBs, PAHs, oestrogenomimetics) and radionuclides (radioactive isotopes of Co, Cs, and Ag). The chosen biological models were a freshwater bivalve (Dreissena polymorpha) and a carnivorous fish (Oncorhynchus mykiss). Chronic metallic waterborne exposures (1-4 µg/l Cd and/or 170-250 µg/L Zn) led to a decrease in radionuclide bioaccumulation with respect to the reference group (Ag and Cs for fish with respectively – 60% and 134Cs and -30%; Co for bivalve with -50%, on average); while no effect was noticed with other radionuclide/organism pairs (Co for fish, Cs and Ag for bivalve). Prior exposure to organic micropollutants enhanced 57Co and 134Cs uptake kinetic parameters from water and retention time in fish; the radionuclide contamination levels of exposed groups were always higher than those obtained from the reference groups (+10% to +60% as a function of the organic micropollutant). Some explanations are given for these first results that underline the relevancy of this new research field.