The Chernobyl reactor accident: the impact on the United Kingdom.

I had originally thought that by this time, nearly 1 year after the Chernobyl reactor accident, I would be in a position to describe fully its impact on the UK in terms of radiation doses, economics and future emergency planning. However, only one of these is reasonably clear-the radiological impact. We shall continue our measurements, particularly those of activity in persons, and doubtless we shall refine our estimates of collective dose, but they are unlikely to change significantly. We can therefore be certain that the radiological impact on the UK was small and that the health effects will not be detectable. Predictions of the consequences of accidental releases of radionuclides have in the past, perforce, relied upon models of environmental transfer. Data on which the models are based were obtained from investigations of weapons fallout and of routine releases from nuclear facilities. The Chernobyl accident provided a situation of activity deposition that was well characterised in time and in geographical distribution, and measurements along environmental pathways will allow us to validate or refine our models. This accidental deposition reinforced the importance of some effects that we knew about-such as the importance of wet deposition-and will cause us to consider the need to take account of specific situations that we had not considered previously in adequate detail-in particular, the behaviour of radionuclides in upland ecosystems. The overall economic impact is not yet clear and, unfortunately, is unlikely to become so until all restrictions on the movement and slaughter of sheep are removed and the farmers have received compensation. The effect on international trade may never be quantified. Some international agencies are evaluating the consequences of Chernobyl and their reports will become available during 1987. International agreements on intervention levels are also still under discussion and it would be premature to speculate about the need for any fundamental revisions to Emergency Reference Levels and derived quantities. Similarly, we are aware of the need for revision of the national emergency plan, but we are awaiting the government decision on this. One effect of the Chernobyl accident, however, is clear: the public's awareness of radiation issues has reached a new height. Members of the public demand information and advice, and better means of communicating these must be provided. Advice to take some action may provoke unnecessary alarm, but advice that no action is required may be distrusted. We cautiously assume that any dose, no matter how small, has some deleterious effect and yet, in situations of accidental releases, we may tell the public that no actions are required to reduced doses that they may consider appreciable and avoidable. We clearly need to promote a better understanding of the nature and acceptability of the risk of radiation doses in such circumstances and we intend to do so.