The term "contaminated land" is defined in the Environmental Protection Act 1990. It refers to the presence of polluting substances on a site (usually in the soil) in certain concentrations above background levels, which may cause harm (directly or indirectly) to humans, animals, vegetation or structures. Numerous land uses have the potential to contaminate sites, some of the more significant are:
There are a variety of ways in which pollutants may enter the natural environment:
In addition to these causes and sources of contamination, further dispersion of contaminants may occur as a result of soil disturbance and movement, wind dispersal, or leaching and drainage into surface and groundwater. The main emphasis of current policy is on restoring contaminated land so that it can be reused for some beneficial purpose such as housing, public open space, new industry or agriculture. Reclamation of this land is justified by the need to conserve unused land, to protect the countryside and to encourage the regeneration of declining industrial areas and inner cities. The regeneration of inner cities is currently receiving much attention but the problem is not solely confined to urban areas, e.g. former land-based disposal sites are now being redeveloped, many of which are in rural or semi-rural locations.