Assessment of the Radiation Dose to Biota and Humans during the Discharge of Iodine by Radiopharmaceutical Production

The production activities of radiopharmaceutical enterprises involve the discharge of technogenic 131I. Based on the example Karpov Scientific Research Institute of Physics and Chemistry (Obninsk), a method for assessing the radioecological situation around the enterprise in long-term dynamics is shown by determining the content of this radionuclide in the components of the natural environment, as well as the dose loads on biota and humans. A model assessment of the average annual volume activity of a radionuclide based on a Gaussian model of scattering and transport of impurities in the atmosphere, allowing us to determine it at any point of the terrain, has been conducted. It was determined that the dose loads on biota varied from 0.5 µGy/day (for bees) to 8.7 µGy/day (for earthworms) and were significantly lower than environmentally safe exposure levels (100 000 and 10 000 µGy/day, respectively). Adult radiation doses ranged from 0.5 to 1.3 µSv/year, which does not exceed the quota of the Karpov Scientific Research Institute dose limit of 300 µSv/year. The necessity of taking into account both the molecular and aerosol forms of 131I in the assessment of the radioecological situation in order to prevent underestimation of the dose load by up to two times is emphasized. The obtained assessments of the radioecological situation around the Karpov Scientific Research Institute in the years 2015–2021 indicate the absence of negative radiation and environmental effects on humans and their environment. The assessment algorithm can be applied to other enterprises producing radioactive iodine discharges.