A Critical Review of the System of Radiation Protection. First Reflections of the OECD Nuclear Energy Agency's Committee on Radiation Protection and Public Health (OECD/NEA, 2000)

The Nuclear Energy Agency's (NEA's) Committee on Radiation Protection and Public Health (CRPPH) has a wide remit to consider, offer informed expert views, and develop ideas on topical issues in radiation protection. In 1999 the CRPPH set up a working group to examine Roger Clarke's initiative on `controllable dose', and on the use of collective dose. Some CRPPH members had expressed concern over the use of collective doses when integrated over long time periods and very large populations. Antonio Susanna of ANPA chaired the group; Tony Bandle and I attended from the UK and there were other members from Ireland, France, USA, Canada, Hungary, Finland, Germany Switzerland, Japan and the OECD. This report sets out the outcome of the deliberations of the group and the CRPPH on how the current system of radiation protection could be improved. Ted Lazo of the CRPPH secretariat presented its main findings at the IRPA meeting in May 2000. Eight areas for improvement were identified, i.e. coherence and clarity, justification, optimisation, collective dose, dose limits, triviality, public protection and protection of the environment. The report discusses each of these areas, and points out difficulties in practical application of the topics and deficiencies which need to be addressed. Some of the major points in the document are as follows. The complexity of radiation protection terminology and lack of simple definitions has contributed to poor communication of key messages and a decline in decision-maker confidence. An internationally agreed glossary of terms would help to address this problem. The concept of dose constraint is not used consistently, and (although a good report by NEA and the EC was published in 1996) it is not widely understood. The scope of a `practice' has caused confusion, particularly when considered with the principle of Justification. The report comments that this broad-based principle of Justification is of little practical use in operational radiation protection. The CRPPH refers to justification with a small `j', meaning the choice of actions on a case by case basis, in relation to medical diagnosis or treatments or in deciding whether a particular activity should be allowed. These decisions on questions of (small `j') justification are much more useful and increasingly important to practitioners and stakeholders. The document recognises that optimisation of protection in some situations is difficult and practical guidance would help, for example in dealing with remediation of contaminated sites, and where risks are transferred from one population to another (e.g. workers to the public, or vice versa). Collective dose is the subject of much debate; the concept has been misused, particularly for public exposures, where there can be considerable uncertainties in the assessments. Using the approach of LNT (linear-no-threshold), large collective doses (sometimes aggregated from very small individual doses to large populations and perhaps summed over many years) can be translated into a number of predicted excess fatalities, without any qualification about the associated uncertainties. On the other hand, collective dose is a useful tool in the comparative sense, particularly when selecting options for controlling occupational exposures. It can inhibit the unreasonable use of dose sharing and aids in following trends in operations such as steam generator replacement. Clear operational guidance for the valid application of collective dose is important. On dose limits, the report comments that ICRP's selection of limits is based on scientific considerations, when the choice of the boundary between the acceptable and unacceptable is a societal judgement. Greater transparency is needed on the selection of limits and on for example the rationale for the different worker and public dose limits. Presentation of the concept of triviality, and similarly ` de minimis ' and `below regulatory concern' has been, at best, of limited success and more often has met with significant opposition. Where experts and regulators may judge exposures to be `trivial', members of exposed populations may consider that they are quite significant or even unacceptable. The report notes that regulators are `concerned' with all exposures; however some may judge that certain low levels of exposure do not require regulatory action. Optimisation, dose constraints, zero release and triviality, and how they are applied within the process of authorisation for release, should be examined in the future. The report discusses the role and use of the LNT hypothesis within the system of radiation protection and public protection in particular. The CRPPH considers that this debate will not be useful because LNT will never be proven or disproven through epidemiological studies. Research on radiobiological mechanisms of carcinogenesis appears promising and should continue with the aim of establishing more precisely the dose-effect relationship. One way to improve understanding could be to show the distinctions between the various stages of pubic protection, i.e. understanding of the scientific aspects and uncertainties of radiation risks, development of regulations and political decision making. The distinctions between these three are often blurred and discussions of the use of LNT would profit from a better distinction between those aspects which are scientific and those which involve social judgements - and which should be resolved through social dialogue. The role of the radiation protection expert (scientist, regulator or decision maker) needs to be redefined with this in mind. The ICRP has provided relatively little guidance on environmental radiation protection. The CRPPH comments that the rationale for making (or not making) recommendations should be more thoroughly and openly discussed by ICRP and other stakeholders. Whilst initially conceived as a study on controllable dose and collective dose, the report goes well beyond these issues into a reflection on the whole system of radiation protection. I would commend this 20 page, A5 size, report to anyone who wishes to gain a quick appreciation of the main issues which need to be addressed in radiation protection at the present time. Further work on the evolution of the system of radiation protection is being taken forward by a successor working group of CRPPH, which I have been invited to chair. I am confident that these deliberations will prove equally valuable.

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