Bone and Head Kidney Radiation Dosimetry for Roach from Radioactively Contaminated Reservoirs: Method Elaboration and Application

To establish causal relationships between radiation exposure and tissue effects, it is necessary to calculate the doses to critical organs and tissues and to evaluate the dose-effect relationship. The tools of non-human biota dosimetry that exist nowadays do not take into account the heterogeneous radionuclide distribution between organs and tissues. In the current study, a computational phantom of the roach body segment was developed based on the assessment of the morphometric parameters of target organs. The spine, ribs and head kidney were considered as target organs for bone and hematological effects of radiation exposure. The dose factors to convert specific activity of incorporated Sr and Cs to dose rates in target organs were calculated based on Monte Carlo simulation of electron and photon transport. One Bq/g of Sr in bone tissue lead to dose rates equal to 1.98, 3.38 and 7.49 μGy/day in the head kidney, ribs and spine, respectively. The accumulation of Cs in the bones results in bone-specific dose rates that are 3-4 times lower than those at the same concentration of Sr. The obtained results were used to calculate doses to the roach from two radioactively contaminated waterbodies of Ural region. Maximum doses were typical of vertebra (1.4 ± 0.2 and 27.0 ± 8.3 mGy/day). They were 1.4-3 times higher than doses head kidney and ribs. One can expect more pronounced bone effects of radiation exposure in the vertebral bodies than in the ribs of fish, and they should be considered as separate target organs in the presence of Strontium isotopes in the environment.