An organ-based approach to dose calculation in the assessment of dose-dependent biological effects of ionising radiation in Arabidopsis thaliana

• Plant dosimetry needs a more detailed model than currently available.
• A simple dosimetric organ-based model for Arabidopsis thaliana is proposed.
• This model is then applied and compared for 241Am, 90Sr and 133Ba.
• DCC values are shown to deviate from those obtained with the ERICA tool.
• Deviations from the ERICA tool might help to refine dose–effect relationships.

There is a need for a better understanding of biological effects of radiation exposure in non-human biota. Correct description of these effects requires a more detailed model of dosimetry than that available in current risk assessment tools, particularly for plants. In this paper, we propose a simple model for dose calculations in roots and shoots of Arabidopsis thaliana seedlings exposed to radionuclides in a hydroponic exposure setup. This model is used to compare absorbed doses for three radionuclides, 241Am (α-radiation), 90Sr (β-radiation) and 133Ba (γ radiation). Using established dosimetric calculation methods, dose conversion coefficient values were determined for each organ separately based on uptake data from the different plant organs. These calculations were then compared to the DCC values obtained with the ERICA tool under equivalent geometry assumptions. When comparing with our new method, the ERICA tool appears to overestimate internal doses and underestimate external doses in the roots for all three radionuclides, though each to a different extent. These observations might help to refine dose–response relationships. The DCC values for 90Sr in roots are shown to deviate the most. A dose–effect curve for 90Sr β-radiation has been established on biomass and photosynthesis endpoints, but no significant dose-dependent effects are observed. This indicates the need for use of endpoints at the molecular and physiological scale.