On the application of an environmental radiological assessment system to an anthropomorphic surrogate

Abstract

Recent developments have seen the expansion of the system of radiological protection for humans to one including protection of the environment against detrimental effects of radiation exposure, although a fully developed framework for integration of human and ecological risk assessment for radionuclides is only at an early stage. In the context of integration, significant differences exist between assessment methodologies for humans and the environment in terms of transfer, exposure, and dosimetry. The aim of this elaboration was to explore possible implications of the simplifications made within the system of environmental radiological protection in terms of the efficacy and robustness of dose-rate predictions. A comparison was conducted between human radiological assessment and environmental radiological assessment for an anthropomorphic surrogate, the results for which, produced by both the environmental and human-oriented risk assessment systems, were critically compared and contrasted. The adopted approach split the calculations into several parts, these being 1) physical transfer in an ecosystem, 2) transfer to humans, 3) internal doses to humans, and 4) external doses to humans. The calculations were carried out using both a human radiological assessment and ecological risk assessment system for the same surrogate. The results of this comparison provided indications as to where the 2 systems are amenable to possible integration and where such integration may prove difficult. Initial stage transport models seem to be an obvious component amenable for integration, although complete integration is arguably unattainable as the differences between endpoints mean that the relevant outputs from the models will not be the same. For the transfer and dosimetry components of 2 typical methodologies, it seems that the efficacy of the environmental system is radionuclide-dependent, the predictions given by the environmental system for (90) Sr and (60) Co being unsatisfactory and those for (239) Pu and (210) Po being evidently poor. Integration in this context might take the form of exploring the biokinetic models developed for humans with regard to selected animals and radionuclides. External dose assessment for environmental and human systems provide results for the surrogate that correspond quite closely providing an indication that integration in this regard is perhaps unnecessary.