Problems of the assessment of contaminated mining sites

In Germany there are numerous relics of former mining activities with enhanced levels of radionuclides of the uranium/radium series. Of special importance are the relics of uranium and other non-ferrous ore mining in the three Federal States of Saxony, Thuringia and Saxony-Anhalt. The majority of these relics is situated in densely populated areas. This gives rise to the question whether measures have to be taken to protect the population from detrimental health impacts. Public concern often concentrates on radioactivity. Health impacts may, however, originate from chemically hazardous substances, too. Such substances like, for instance, arsenic, often accompany radioactive contamination in mining relics. Also, mining safety, landscape conservation and other aspects may play a significant role in the decision-making process, especially for large and complex mining sites. This is, however, outside the scope of the present paper, which is confined to the discussion of problems associated with the assessment of mining sites contaminated with both enhanced levels of naturally occurring radionuclides and chemically toxic/carcinogenic substances. Sites with mixed contaminants like mining relics may cause special problems in the assessment of hazards to human health. Different scientific approaches and historic developments led to considerable differences in existing regulations. Both, on the national and international scale efforts are made towards a harmonization. Having reviewed studies carried out in Germany we arrived at the conclusion that generation of a common risk scale for all kinds of hazards seems to be a too challenging problem to be solved within a foreseeable time scale. It is reasonable, at least in principle, to define a unified metric for carcinogenic effects of ionizing radiation and harmful chemicals. Even this needs a lot of research work as a basis for adaptations in the legal systems. What seems to be reasonable and in our opinion is much more important at the current stage is the harmonization of exposure scenarios, pathways and parameters because they are comprehensible to everyone. A comparison of existing provisions and recommendations has proved that the harmonization of parameters used for exposure calculations is of special importance. The ideal solution would be to use the same parameters for the same pathways independently from the specific substance (ingestion rates of plants and soil, breathing rates and dust concentrations). It is problematic, however, to bring parameters in line to each other as this could cause conflicts with other well established provisions in the different fields. On the long run, however, such harmonization is indispensable