Environmental Protection: Transfer Parameters for Reference Animals and Plants

Abstract

In Publication 103 (ICRP, 2007), the Commission included a section on the protection of the environment, and indicated that it would be further developing its approach to this difficult subject by way of a set of Reference Animals and Plants (RAPs) as the basis for relating exposure to dose, and dose to radiation effects, for different types of animals and plants. Subsequently, a set of 12 RAPs has been described in some detail (ICRP, 2008), particularly with regard to estimation of the doses received by them, at a whole-body level, in relation to internal and external radionuclide concentrations; and what is known about the effects of radiation on such types of animals and plants. A set of dose conversion factors for all of the RAPs has been derived, and the resultant dose rates can be compared with evaluations of the effects of dose rates using derived consideration reference levels (DCRLs). Each DCRL constitutes a band of dose rates for each RAP within which there is likely to be some chance of the occurrence of deleterious effects. Site-specific data on Representative Organisms (i.e. organisms of specific interest for an assessment) can then be compared with such values and used as a basis for decision making. It is intended that the Commission's approach to protection of the environment be applied to all exposure situations. In some situations, the relevant radionuclide concentrations can be measured directly, but this is not always possible or feasible. In such cases, modelling techniques are used to estimate the radionuclide concentrations. This report is an initial step in addressing the needs of such modelling techniques. After briefly reviewing the basic factors relating to the accumulation of radionuclides by different types of biota, in different habitats, and at different stages in the life cycle, this report focuses on the approaches used to model the transfer of radionuclides through the environment. It concludes that equilibrium concentration ratios (CRs) are most commonly used to model such transfers, and that they currently offer the most comprehensive data coverage. The report also reviews the methods used to derive CRs, and describes a means of summarising statistical information from empirical data sets. Emphasis has been placed on using data from field studies, although some data from laboratory experiments have been included for some RAPs. There are, inevitably, many data gaps for each RAP, and other data have been used to help fill these gaps. CRs specific to each RAP were extracted from a larger database, structured in terms of generic wildlife groups. In cases where data were lacking, values from taxonomically-related organisms were used to derive suitable surrogate values. The full set of rules which have been applied for filling gaps in RAP-specific CRs is described. Statistical summaries of the data sets are provided, and CR values for 39 elements and 12 RAP combinations are given. The data coverage, reliance on derived values, and applicability of the CR approach for each of the RAPs...

Accuracy in dosimetry of diagnostic agents: impact of the number of source tissues used in whole organ S value-based calculations

“…Other differences between the ICRP voxelized and the CE stylized reference phantoms are between definitions of different tissues as for example the colon and lungs. In the ICRP voxelized reference phantoms, the colon is divided into three sections the left colon (RC-stem), right colon (LC-stem), and rectosigmoid colon (RS-stem) [5,6]. In the CE stylized reference phantoms, the colon is divided into two sections the upper large intestine and the lower large intestine [11].…”

“…In the CE stylized reference phantoms, the colon is divided into two sections the upper large intestine and the lower large intestine [11]. The lungs are represented as one source and target tissue in the CE stylized reference phantoms, in our ICRP voxelized reference phantoms calculations the lungs were represented as one source tissue and four target tissues (bronchi basal cells, bronchi secretory cells, bronchiolar secretory cells, and alveolar-interstitial) [5,6]. The fractional weights of these four lung tissues were bronchi basal cells (1/6), bronchi secretory cells (1/6), bronchiolar secretory cells (1/3), and alveolar-interstitial (1/3) [6].…”

“…Dosimetric calculations representing the ICRP methodology were performed using the ICRP Publication 110 voxelized reference phantoms [5], ICRP Publication 133 SAF [6] calculated using ICRP Publication 107 nuclear decay data [10], and ICRP Publication 103 tissue weighting factors [7]. Representing the CE stylized reference phantoms the OLINDA/EXM version 1.0 [11] software was used, which uses tissue weighting factors from ICRP Publication 60 [4] and organ weights from ICRP Publication 89 [12].…”

“…Using a previously published comprehensive data set consisting of sixteen patients receiving 68 Ga-DOTA-TATE, we examine the impact of source tissue number on estimates of the patient's effective dose coefficient. The analysis was performed using radionuclide S values based on Cristy-Eckerman stylized reference phantoms (CE stylized reference phantoms) [3] using tissue-weighting factors, w T , from the International Commission on Radiological Protection (ICRP) Publication 60 [4], which were compared to the recent ICRP Publication 110 voxelized reference phantom series (ICRP voxelized reference phantoms) and specific absorbed fractions (SAF) from ICRP Publication 133 [5,6], using w T from ICRP Publication 103 [7].…”

Radiological impact assessment approaches for Life Cycle Assessment: a review and possible ways forward

“…The approach is similar to that developed for the assessment of human impact, based on a set of Reference Animals and Plants defined as hypothetical entities with assumed biological characteristics that are used to relate exposure to dose and dose to effects. Committee 5 published in 2008 a first set of Reference Animals and Plants along with their relevant databases (ICRP 2008), followed by two more reports covering approaches to model the transfer of radionuclides to non-human biota (ICRP 2009) and to extend the application of the radiological protection system to different exposure conditions, e.g. unplanned events) (ICRP 2014).…”