Radiological Benchmarks for Effects on Aquatic Biota at the Oak Ridge Reservation

The diversity of non-human biota is a specific challenge when developing and applying dosimetric models for assessing exposures of flora and fauna from radioactive sources in the environment. Dosimetric models, adopted in Publication 108, provide dose coefficients (DCs) for a group of reference entities [Reference Animals and Plants (RAPs)]. The DCs can be used to evaluate doses and dose rates, and to compare the latter with derived consideration reference levels (DCRLs), which are bands of dose rate where some sort of detrimental effect in a particular RAP may be expected to occur following chronic, long-term radiation exposure, as outlined in Publication 124. These dosimetric models pragmatically assume simple body shapes with uniform composition and density, homogeneous internal contamination, limited sets of idealised sources of external exposure to ionising radiation for aquatic and terrestrial animals and plants, and truncated radioactive decay chains. This pragmatic methodology is further developed and systematically extended in this publication, which supersedes the DC values of Publication 108. Significant methodological changes since Publication 108 include: implementation of a new approach for external exposure of terrestrial animals with an extended set of environmental radioactive sources in soil and in air; considering an extended range of organisms and locations in contaminated terrain; transition to the contemporary radionuclide database of Publication 107; assessment-specific consideration of the contribution of radioactive progeny to DCs of parent radionuclides; and use of generalised allometric relationships in the estimation of biokinetic or metabolic parameter values. These methodological developments result in changes to previously published tables of DCs for RAPs, and revised values are provided in this publication. This publication is complemented by a new software tool, called ‘BiotaDC’, which enables the calculation of DCs for internal and external exposures of organisms with user-defined masses, shapes, and locations in the environment and for all radionuclides in Publication 107.

Section: Extension Of the Existing Icrp Dosimetric Systemmentioning

confidence: 99%

ICRP Publication 136: Dose Coefficients for Non-human Biota Environmentally Exposed to Radiation

Ulanovsky¹,

Copplestone²,

Batlle³

2017

“…Criteria for truncation of decay chains are commonly based on the selection of an upper limit for the half-life of a daughter to be accounted for in the given chain. Selection of the upper limit varies in the literature, and it can be found as 1 d (Amiro, 1997), 30 d (Jones, 2000;DOE, 2002), 180 d (Yu et al, 1993), and 100 y (Higley et al, 2003). An approach, adopted in Publication 108, used the value of 10 d as the chain cut-off criterion, following an approach introduced in the FASSET and ERICA projects (Larsson, 2004(Larsson, , 2008 and used in the ERICA tool (Brown et al, 2008).…”

Section: Effect Of Radioactive Progeny On Dccsmentioning

confidence: 99%

Dosimetry for animals and plants: contending with biota diversity

Ulanovsky

2016

Diversity of living organisms and their environmental radiation exposure conditions represents a special challenge for non-human dosimetry. In order to contend with such diversity, the International Commission on Radiological Protection (ICRP) has: (a) set up points of reference by providing dose conversion coefficients (DCCs) for reference entities known as 'Reference Animals and Plants' (RAPs); and (b) used dosimetric models that pragmatically assume simple body shapes with uniform composition and density, homogeneous internal contamination, a limited set of idealised external radiation sources, and truncation of the radioactive decay chains. This pragmatic methodology has been further developed and extended systematically. Significant methodological changes include: a new extended approach for assessing doses of external exposure for terrestrial animals, transition to the contemporary ICRP radionuclide database, assessment-specific consideration of the contribution of radioactive progeny to dose coefficients of parent nuclides, and the use of generalised allometric relationships in the estimation of biokinetic or metabolic parameters. The new methodological developments resulted in a revision of the DCCs for RAPs. Tables of the dose coefficients have now been complemented by a web-based software tool, which can be used to calculate a user-specific DCC for an organism of arbitrary mass and shape, located at user-defined height above the ground, and for an arbitrary radionuclide and its radioactive progeny.

“…Many of these models are providing the basis of the current studies being made within FASSET (Copplestone et al, 2001) including comparisons using Monte Carlo simulations. Variations of these environmental geometry categories are also already commonly applied (Amiro, 1997;Jones, 2000;Higley et al, 2003a,b,c;USDOE, 2002). An equally important consideration is that of the possible range of 'environmental' geometries within which these dose models could be set.…”

Section: Dose Models and Exposure Geometriesmentioning

confidence: 99%

“…The procedures necessary to do this can be simple or complex, and tiered approaches can be introduced to facilitate their use. The graded-approach system developed by the USDOE (using dose-limit standards) and which is used at some USDOE sites and facilities (Jones, 2000;Higley et al, 2003a,b,c;USDOE, 2002), and the approach recommended to the CNSC by its Advisory Committee on Radiological Protection (ACRP, 2002) based on aspects of the tiered approach of Environment Canada's ecotoxicological risk assessment, plus the graded approach of the USDOE for some of its contaminated sites, are all illustrative of systems developed, or under development, as such compliance tools. These approaches and methodologies also provide data and information relevant to other managerial requirements and assessments.…”

Section: Dose Consideration Levels For Non-human Speciesmentioning

confidence: 99%

A framework for assessing the impact of ionising radiation on non-human species

Valentin¹

2003

In its 1990 Recommendations, the ICRP indicated that it believed that the standards of environmental control needed to protect man to the degree currently thought desirable would ensure that other species are not put at risk. The ICRP considers that its system of radiological protection has provided a fairly good indirect protection of the human habitat. However, no internationally agreed criteria or policies explicitly address protection of the environment from ionising radiation, and it is difficult to determine or demonstrate whether or not the environment is adequately protected from potential impacts of radiation under different circumstances. The present report suggests a framework, based on scientific and ethical-philosophical principles, by which a policy for the protection of non-human species could be achieved. The primary purpose of developing such a framework is to fill a conceptual gap in radiological protection; it does not reflect any particular concern over environmental radiation hazards. The proposed framework is designed to harmonise with the ICRP's approach to the protection of human beings, but does not intend to set regulatory standards. Instead, the proposed framework is intended to be a practical tool to provide high-level advice and guidance for regulators and operators. An agreed set of quantities and units, a set of reference dose models, reference dose-per-unit-intake (or unit exposure), and reference fauna and flora are required to serve as a basis for the more fundamental understanding and interpretation of the relationships between exposure and dose and between dose and certain categories of effect, for a few, clearly defined types of animals and plants. As a first step, a small set of reference fauna and flora with supporting databases will be developed by the ICRP. Others can then develop more area- and situation-specific approaches to assess and manage risks to non-human species.