Contemporary radiation doses to murine rodents inhabiting the most contaminated part of the EURT

The contemporary radiation doses to the organs and tissues of murine rodents inhabiting the most contaminated part of the EURT were estimated. The bones of animals trapped in 2005 at territories with a surface ⁹⁰Sr contamination of 24–40 MBq/m² were used for dose reconstruction. The concentration of ⁹⁰Sr in the animals' skulls was measured using the nondestructive method of bone radiometry. The dose estimation procedure included application of the published values of absorbed fractions of beta-radiation energy for different combinations of source and target organs, accounting for the distribution of radionuclide by organs and tissues. Twelve conversion coefficients were obtained to link the skeleton ⁹⁰Sr concentration and doses to eleven organs and the whole body. The whole-body dose rate on the 45th day after the beginning of exposure normalised to whole-body activity is 0.015 (mGy day⁻¹)/(Bq g⁻¹). The estimation yields the following values of doses for Microtus agrestis, Sylvaemus uralensis and Clethrionomys rutilus, respectively: maximum absorbed doses in the skeleton: 267, 121 and 160 mGy; mean whole body internal doses: 37, 14 and 23 mGy; mean internal dose rates on the last day before trapping: 1.2; 0.44 and 0.75 mGy/day. Approaches to the assessment of doses to foetuses and to offspring before weaning were also developed. - Highlights: • Doses to murine rodents inhabiting the most contaminated part of EURT are estimated. • Coefficients linking skeleton ⁹⁰Sr concentration and organ doses are suggested. • Maximal contemporary mice skeleton dose is 267 mGy per life. • Average whole body dose rate exceeds 1 mGy/day