What do we mean by Risk
The term risk is widely used in different contexts and circumstances, often with differing definitions. In Government publications about the environment,
it has been given the following definition:
Risk is a combination of the probability, or frequency, of occurrence of a defined hazard and the magnitude of the consequences of the occurrence.
The idea of the ˇ§pollutant linkageˇ¨
In the context of land contamination, there are three essential elements to any risk:
„h a contaminant ˇV a substance which is in, on or under the land and has the potential to cause harm or to cause pollution of controlled waters
„h a receptor ˇV in general terms, something that could be adversely affected by a contaminant, such as people, an ecological system or a water body, and
„h a pathway ˇV a means by which a receptor can be exposed to, or affected by, a contaminant.
Each of these elements can exist independently, but they create a risk only where they are linked together ˇV so that a particular contaminant affects a particular
receptor through a particular pathway. This combination of contaminant-pathway-receptor is described as a pollutant linkage.
On any individual site, there may be only a single pollutant linkage or there may be several. Different pollutant linkages may be related ˇV for example, the
same contaminant may be linked to two or more distinct types of receptor by different pathways ˇV or different contaminants may affect the same receptor. Not
all receptors will be relevant in every context. Each pollutant linkage needs to be separately identified, understood and dealt with if appropriate.
Deciding whether risk matters
Without a pollutant linkage, there is not a risk. But even where there is a pollutant linkage the question still needs to be asked as to whether the level of risk
justifies action to deal with the risk. This again will depend on the context.
For example, Government policy for dealing with past land contamination focuses on taking action where there are ˇ§unacceptable risks to human health and
the environmentˇ¨ in relation to the current use of the land and for certain defined receptors. This is carried forward into the definition of contaminated
land under the regulatory regime in Part IIA of the Environmental Protection Act 1990. In planning and development control, the aim is to ensure that there are
no unacceptable risks not only to the receptors relevant to Part IIA but also to others which may be covered by other regimes, but again taking into account the
use of the land ˇV in this case the proposed new use.
The question of whether risk is unacceptable in any particular case involves not only scientific and technical evaluation of the particular circumstances,
but also appropriate criteria to judge the risk (exactly what risk would be unacceptable?). In the context of Part IIA, the Government has provided general
criteria in the statutory guidance. In other contexts, other decision-makers (such as site owners or planning authorities) may need to establish the appropriate