Appropriate measures for minimising and controlling the debris environment have been clearly identified in the past. This paper addresses the cost / benefit ratio of debris mitigation. The costs are determined by the system and subsystem modifications and the fuel needs for orbit manoeuvres associated with debris mitigation. The benefit can be expressed in spacecraft that will not run into a damaging collision due to debris mitigation. Direct and indirect benefits are considered. The analysis was performed by an upgraded version of the long term debris environment model LUCA. First results are presented. A significant impact on the cost benefit ratio is the bandwidth of the growth of the future population due to uncertainties related to the traffic models, statistical effects, etc. The related bandwidth is quantified and it is shown, which spatial regions could be subject to uncontrolled population growth taking into account also economic considerations.