Inter-comparison of absorbed dose rates for non-human biota

Abstract

A number of approaches have been proposed to estimate the exposure of non-human biota to ionizing radiation. This paper reports an inter-comparison of the unweighted absorbed dose rates for the whole organism (compared as dose conversion coefficients, or DCCs) for both internal and external exposure, estimated by 11 of these approaches for selected organisms from the Reference Animals and Plants geometries as proposed by the International Commission on Radiological Protection. Inter-comparison results indicate that DCCs for internal exposure compare well between the different approaches, whereas variation is greater for external exposure DCCs. Where variation among internal DCCs is greatest, it is generally due to different daughter products being included in the DCC of the parent. In the case of external exposures, particularly to low-energy beta-emitters, variations are most likely to be due to different media densities being assumed. On a radionuclide-by-radionuclide basis, the different approaches tend to compare least favourably for (3)H, (14)C and the alpha-emitters. This is consistent with models with different source/target geometry assumptions showing maximum variability in output for the types of radiation having the lowest range across matter. The intercomparison demonstrated that all participating approaches to biota dose calculation are reasonably comparable, despite a range of different assumptions being made.

Protection of the environment from ionising radiation in a regulatory context (PROTECT): Assessment approaches – practicality, relevance and merits

“…In part, this is a consequence of the different organisms considered in the three models. It is also in agreement with other comparisons of models/approaches used to estimate exposure of biota which have demonstrated that the dosimetry components generally estimate comparable results [1][2][3]. The greater variability observed in estimated RQ values between models when assuming 1 Bq kg −1 in freshwater sediments may be the consequence of RESRAD-BIOTA using terrestrial soil-soil water k d values rather than freshwater sediment-water k d values [10].…”

“…A number of models/approaches/tools to estimate the exposure of wildlife to ionising radiation have been produced or are being developed for use in assessments [1][2][3]. Many of the approaches use some form of tiered (iterative) assessment consistent with approaches used for other stressors.…”

Findings and recommendations from an international comparison of models and approaches for the estimation of radiological exposure to non-human biota

“…Estimates were made for seven radionuclides ( 3 H, 14 C, 60 Co, 90 Sr, 137 Cs, 238 U and 241 Am) chosen to cover a range of energies and radiation types. The results of this exercise are described fully by Vives i Batlle et al [5].…”

Comparison of Photon and Electron Absorbed Fractions in Voxel-Based and Simplified Phantoms for Small Animals

“…1) The ICRP has assessed absorbed fractions (AFs), the fraction of energy emitted by a radiation source which is absorbed within the target organ, in Reference Animals and Plants for understanding dose responses, radiation-related side-effects and the consequences of such effects. 2) The assessment has been performed only in the whole bodies of the Reference Animals for simplified dosimetric models which do not include internal organs except for the Reference Deer. 3) Besides the efforts of ICRP for radiation protection of animals, many various studies have been done on dosimetry of small animals, such as rats and mice, which are widely used in preclinical evaluations of radiopharmaceuticals.…”