Methodology for determining action levels for clean-up of contaminated urban and agricultural environments

A methodology for determining justified action levels for clean-up of contaminated environments has been elaborated based upon dose reductions and monetary costs associated with the clean-up or remedial measures. Action levels can be expressed as dose or contamination levels above which clean-up is justified and below which it is not. This paper discusses the factors needed to determine such action levels. The most important of these factors are the efficiency of the clean-up and the monetary costs of the clean-up operation. Examples of justified action levels for clean-up of urban and agricultural environments have been determined from uncertainty analyses. With selected parameter distributions for clean-up of urban and semi-urban environments, justified action levels for clean-up are found to be in the range of about 1-10 mSv y(-1). With selected parameter distributions for agricultural countermeasures, action levels for reduction of activity content in milk have been determined to be from less than 100 Bq L-1 up to a few thousand Bq L-1, corresponding to residual individual ingestion doses of about 0.1-0.5 mSv y(-1). The presented methodology, which can be extended to include more complex environments, can in a simple way give the decision maker an indication of when it is justified to clean a contaminated environment.