by Klaus Becker, Berlin

The question whether radon in above-ground situations represents a health hazard is important not only because of the high economic and social costs associated with radon surveys and the reduction of radon levels in homes, in the remediation of former uranium mining areas (e.g. in Saxony, Eastern Germany), etc., but - perhaps more importantly - because the radon controversy became an important test case for the validity of the LNT hypothesis, the collective dose concept, current RBE estimates, and other central issues of legislation and regulatory control of low radiation doses. On the one hand, some institutions claim, based on miners’ and a few case-control epidemiological studies, that large numbers of additional lung cancers in the population are due to residential radon. On the other hand, various recent studies, e.g. with never-smoking women in high radon areas, as well as animal and cell experiments indicate thresholds, perhaps even biopositive effects including the reduction of other types of cancer in areas with increased residential radon levels.

A survey of recent data leads to the following conclusions:

1. There is no international agreement regarding intervention levels for residential radon old and new buildings, and at the work place.

2. Linear extrapolation from very high miner exposures to low levels in homes is not feasible because of the very different conditions and many confounders in mines, as well as uncertain dosimetry. Epidemiological studies indicating an increased residential lung cancer risk are subject to substantial errors, in particular regarding radon dosimetry and the retrospective determination of smoking habits. Thus is evidently impossible to detect a possible minor contribution of radon, in case it should exist.

3. There are indications for an U-shaped dose-effect relationship and or threshold around 1000 Bq/m3. In all but a few exceptional cases, the cost/benefit ratio does not justify residential radon reduction, environmental remediation programs, or costly construction regulations, and radon balneology has been shown to be beneficial for arthritis, Morbus Bechterew, etc.

4. Such findings have obvious consequences for low dose radiation risk assessment and regulatory control for radiation protection in general as well as low-dose cost/benefit assessment, with its various socio-economic and ethical aspects. The key question is apparently: How much of a society’s limited resources should be devoted to the reduction of highly hypothetical instead of REAL individual or public health risks

Prof. Dr. Klaus Becker Radiation, Science & Health Boothstr. 27, D-12207 Berlin Phone/Fax 004930-772-1284 E-mail: prof.dr.klaus.becker@t-online.de For pre-prints.