The International Commission on Radiological Protection (ICRP) has released for comment/consultation a draft publication entitled Environmental Protection: Transfer Parameters for Reference Animals and Plants.
The ICRP’s radiation protection program has been expanded to include protection of the environment from ionizing radiation; specifically, preventing or reducing harm to the environment, maintenance of biological diversity, conservation of species, and health of habitats, communities and ecosystems (ICRP, 2007). In order to achieve this objective, the ICRP has decided to use a system of simplified Reference Animals and Plants (RAPs) for assessing effects of radiation on non-human biota, based on the concept developed by Pentreath (2009).
The extent to which plants and animals are exposed to radiation can be measured directly, or estimated using exposure modeling. In the absence of empirical data, however, a set of reference data values that could be used to estimate exposure to radionuclides in aquatic and terrestrial environments is required. The subject draft publication is intended to provide appropriate transfer parameters for transfer of radionuclides to the RAPs from the relevant environmental compartments (i.e. soil, water and air).
CNSC staff has reviewed the subject document from the perspective of environmental protection and the following comments are provided for your consideration.
The document is generally well written and avoids ambiguities. It, however, encompasses a limited set of organism types that might be considered as typical of the terrestrial, freshwater, and marine environments. This has resulted in the designation of 12 RAPs, and excluded some key species in the food chain such as freshwater invertebrates. In contrast to current work being done under the auspices of the IAEA’s EMRAS II program on development and publication of a handbook for wildlife transfer factors, which is based on a fairly extensive database, the subject ICRP document is based on a limited database and appears to be less comprehensive.
Furthermore, there are discrepancies between the two documents with respect to the values for concentration ratios (CR) reported e.g. the CR for uranium in trout (it is 21 in the current ICRP draft vs. 100 in the IAEA document). In the ICRP document, it is unclear if conversation factors were utilized to convert CR values for organs into CR values for whole organisms, given that only CR values for the latter are listed. This discrepancy can result in differences of opinion among stakeholders (e.g. licensees and regulators) about which values to apply in their assessments.
The RAP approach essentially involves extrapolation from other data, and most of the values presented in this document are derived rather than empirical. There should be a discussion included which addresses QA/QC analysis and representativeness of the source data used in this document. Otherwise, this will present difficulties with respect to defensibility of the derived CR values presented in the document.
Overall, this document may be of limited utility for the purposes of risk assessment. There are also many typographical errors which could have been easily corrected. Specific and typographical/editorial comments are presented in the table below.
Line # Comment
184 Speciation of the radionuclide may also influence uptake by biota.
252 In section 1.2.1, under physical and chemical processes, environmental transformation of radionuclides (i.e. speciation, decay, etc.) should be included.
328 Include terrestrial birds in the inhalation pathway.
336 Include ingestion of detritus and sediment in this exposure pathway.
372 Include benthic invertebrates in Figure 1.2.
891 Table 3.2; bee is listed as a RAP for flying insect. This may not be appropriate as bees have a life cycle (i.e. caste system) that is very different from typical flying insect.
1142 Table 4.1, the row with element K has no CR values.
1153 Table 4.2, the row with element K has no CR values.
1201-1206 Only transfer from soil to bees is considered. Inhalation pathway for bees is also relevant, as bees forage over long distances.
1235 The use of CR data for trout as surrogate for frog may not be appropriate; given that most of the adult life stage of frog is terrestrial. This, however, is elucidated further in the document on lines 1253 -1257.
1263 Table 4.3, the rows with elements Ir and S have no CR values.
1321 Adult flatfish also receive an external dose from close contact with sediment.
See below There are inconsistencies between the Baseline Concentration Ratio (CR) tables in Section 4 and the Detailed Statistical Information on Concentration Ratios tables in Annex A. The Section 4 tables should be made consistent with the source data in Annex A. Specifically:
1603 Table A.1.2 has no CR values for element S. This data should be included or on Line 1153, table 4.2, element S for pine tree should not be identified as coming from statistical information.
1614 Table A.1.3 has no CR values for elements Ra and Ru. This data should be included or on Line 1153, table 4.2, element S for earthworm should not be identified as coming from statistical information.
1626 Table A.1.6 includes CR values for element Ra. On Line 1142, Table 4.1, element Ra for duck should be identified as coming from statistical information.
1626 Table A.1.6 has no CR values for element Tc. This data should be included or on Line 1142, table 4.1, element Tc for duck should not be identified as coming from statistical information.
1629 Table A.1.7 has no CR values for element U. This data should be included or on Line 1142, table 4.1, element U for rat should not be identified as coming from statistical information.
1674 Table A.3.1 includes CR values for element K. On Line 1278, table 4.4, element K for brown seaweed there is no CR value. It is unclear why the value from table A.3.1 was not included.
1686 Table A.3.3 includes CR values for element K. On Line 1278, table 4.4, element K for flatfish there is no CR value. It is unclear why the value from table A.3.3 was not included.
1686 Table A.3.3 includes CR values for element Ni. On Line 1278, Table 4.4, element Ni for flatfish should be identified as coming from statistical information.
34 Indent between section number and title.
70 The typo “…environmentasl...” should be corrected.
146 The typo “…theoreticl…” should be corrected.
152 The typo “…intentended…” should be corrected.
375 Figure 1.2 Aquatic exposure pathways for fish and seaweed. The numbering the figure begins at (iii). This figured should be re-numbered to begin at (i).
546 Numbering of paragraphs have restarted to (39) when it should be (42).
567 – 568 Sentence has been repeated in line 562.
920 The typo “…eslewhere…” should be corrected.
974 The typo “…w…” should be corrected.
1232 The typo “…extsneive…” should be corrected.
2124 – 2143 The titles of the tables for derived concentration for terrestrial ecosystems are included but the actual tables are missing. These tables should be included.
2147 – 2158 The titles of the tables for derived concentration for freshwater ecosystems are included but the actual tables are missing. These tables should be included.
ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37 (2-4).
Pentreath, R.J., 2009. Radioecology, radiobiology, and radiological protection: frameworks and fractures. J. Environ. Radioactv. 100 (1019-1026).