ICRP publication 108 introduced the concept of Reference Animals and Plants (RAPs) for environmental radiation protection. This was in analogy to the use of a Reference Person in radiation protection for human individuals and makes use of endpoints such as mortality and reproductive success of these reference organisms to evaluate the potential negative effects of radiation on an ecosystem. However, it is widely recognized that an ecosystem cannot be completely described as a simple collection of organisms, and complex properties emerge from the interaction of its individuals. Therefore, the individual organism approach based on the human model might not be enough for radiation protection of ecosystems. A more holistic approach might be warranted, with more appropriate endpoints such as diversity and changes in ecosystem balance.
Bacteria and other unicellular organisms were not included among the reference organisms due to their high resistance to radiation. However, recent studies have shown that low radiation doses can have a wide range of effects on bacteria, from inducing stress to enhancing growth and changing composition of bacterial communities, and potentially inducing resistance to antibiotics. This suggests that smaller organisms should not be ignored when considering environmental radiation protection, and on the contrary, could even serve as a tool to monitor ecosystem health and response to radiation.
Moreover, the 12 Reference Animals and Plants chosen came mainly from temperate climates in northern regions and might not be representative for other types of ecosystems. Information on more reference organisms might be necessary for other types of ecosystems but not readily available for quick reference. The environmental radiation protection community could benefit from a collaborative database with curated information on different organisms, as is already done in several fields in biology and life sciences. A document could then be developed with guidance on how to decide local dose criteria based on key radiobiological data of representative organisms in a local ecosystem. An open database that aggregates relevant data would additionally facilitate application of machine learning techniques to the highly complex problem of evaluating the potential impact of radiation in an ecosystem.
Keywords: environmental protection; non-human biota
I think both organism level approaches and ecosystem approaches are complimentary to each other, specially because reference levels and RAPS might be easier and quicker to apply. I mainly think bacteria can be used as a tool to monitor ecosystems, and its the ecosystem itself that should be protected, but this can also indirectly protect them (or rather protect the balance of species in bacterial communities that can have an impact on the whole ecosystem).
Edith, thank you for your interesting presentation. Do you think an ecosystem approach using some of the endpoints you mentioned could replace the current approach, or would it also be necessary to continue to use reference levels and RAPs? Also, do you think that effects seen in bacteria are mainly useful as an indicator of ecosystem health, or is there a need to explicitly protect microorganisms?