Societal sensitivity to environmental quality is increasing at the same time as the accumulated evidence of poor past practices are becoming conspicuous. Much of present day contamination of the environment was made by agencies which cannot be identified or companies which no longer exist. It is debatable whether polluters should be liable for former actions which accorded to the prevailing laws and scientific knowledge of the time. However, the tendency is increasingly for organizations to be held responsible for the errors of the past where these have produced costly and persistent contamination problems in the present. Examples are contamination of soils or groundwater through dumping of chemicals or leaching of toxins from wastes.
In the UK in 1992, it was estimated that the cost of cleaning up contaminated land was in excess of 30 billion pounds. Completion of a register of contaminated land has been delayed indefinitely by the Government amid fears by property developers that it might erode the value of sites and bring demands for an expensive clean up, and concerns by the Government that inner city regeneration programmes could be adversely affected.