Use of the root elongation test to assess uranium toxicity to a higher plant model: case study for uranium and green bean (Phaseolus vulgaris)
Congress title :SETAC Europe 17th Annual Meeting
Congress town :Porto
Congress date :20/05/2007
Few data on effects of radionuclides on higher plants concern chronic exposure to low doses following internal contamination after root absorption and most are inadequate to be used in an ecological risk assessment (ERA). Recently, ERA methodology for radioactive substances has been built on the basis of the existing system for chemicals. For the effect analysis, it relies on the use of 'dose-response' relationships obtained from standardized bioassays. These bioassays had to be adapted to the specificity of radionuclides (technical and radioprotection constraints, radiological dose calculations, radio- and chemo-toxicity). The root elongation test was used to assess the toxicity of uranium on plant roots due to the lack of data, the relevancy of the soil-plant exposure pathway and the high affinity of roots for uranium. Dose-response for growth endpoints often exhibits hormetic and non-linear pattern and mechanistic approaches are often needed to understand this complexity. Here we tested the influence of uranium aqueous speciation on the bioaccumulation and effects of uranium on bean plants roots and highlighted some interfering parameters (e.g. P).