Non-destructive biological and chemical traits to track down long term effects of environmentally relevant low concentrations of pharmaceutical mixtures using two freshwater species


  • Desbiolles Fanny
  • de Jong Laetitia
  • Moreau Xavier
  • Laffont-Schwob Isabelle
  • Malleret Laure
  • Tiliacos Christophe
  • Tiliacos Nicolas
  • Wong-Wah-Chung Pascal

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Up to now, little is known about biological effects of chronic exposure to pollutants mixture at low environmental concentrations. Current bioassays investigate short time exposure (72h or 96h) and high concentrations that are greater than those found in the aquatic environment. Effects of pollutant mixtures are still poorly illustrated and understood even if most ecotoxicologists have pointed out the pertinence of such investigations to assess environmental risk. Moreover, even if normalized bioassays must be reliable, literature reveals contrasting results. Through an interdisciplinary study involving environmental chemists and ecotoxicologists, we screened pollutants commonly and endlessly found at low concentrations. Among them, pharmaceutical compounds represent typically pollutants found at low but persistent concentrations, mainly due to continuous rejects. Thus, in this work, we evaluated the effects of two pharmaceuticals ( carbamazepine and oxcarbazepine) and one metabolite (9-carboxylique acridine acid), taken alone or in combination at very low concentration levels, similar to those found in natural water bodies. To carry out the hereby proposed bioassays, two representative species of freshwater environment have been selected: the macrophyte Lemna minor L., already used in normalized tests and the Metazoan Hydra attenuata Pall., which is foreseen as a good animal model by many scientists. Because of their rapid reproductive ability, these two species are particularly adapted to study the long term exposure effects. We propose an original approach based on multiple biological responses in order to detect deleterious effects of long-term exposure that could not be detected by classical bioassays. For both models, we have retained biological endpoints that could be obtained by non-destructive investigations: optical measurements of primary and secondary metabolites in L. minor and a monitoring of morphological alterations, feeding behavior and reproductive rates in H. attenuata. Our results revealed that both chemical traits such as phytometabolites in the Lemna model and biological ones in the Hydra model may inform on ecotoxicological effects of the compounds investigated. Indeed, the development of new ecotoxicological tools as those proposed here must be encouraged to properly assess the complex biological effects due to chronic exposure to pollutants mixture at low concentrations in water bodies.

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