Introduction to Ecological Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 593

influence from human activities, often seen as the basis of Ecological Integrity, is
not necessarily the optimal condition for the soil ecosystem. Although many human
activities are widely recognized as a major plague on ecological systems, humans
may also, generally for their own benefit, enhance the soil ecosystem. From this
perspective, the condition of pristine ecosystems may not always be considered as
the ideal goal for a managed ecosystem, but it can be used as a reference point (or
baseline, or benchmark) for an ecosystem.
Contrary to Human Health Risk Assessment, which focuses on one sin-
gle (although extremely complex) species (i.e., human beings), Ecological Risk
Assessment focuses on the total soil ecosystem including numerous completely dif-
ferent species (see Section 13.2.2 ). Protection of the soil ecosystem is important
because of its intrinsic value (as was stated at the 1992 United Nations Conference
on Environment and Development (UNCED) in Rio de Janeiro (United Nations
1992 ), but also because of the Ecosystem Services of the soil. Man depends on
healthy soil for his survival and supply of food, energy and clean groundwater. For
the provision of these services, organisms are important. Therefore, if we want to
protect these services, we have to protect the organisms performing them. However,
effects on the ecosystem cannot be assessed as the sum of the effects on all sepa-
rate species involved. In fact, a major problem in Ecological Risk Assessment is the
extrapolation of observations from individual and population levels to the ecosys-
tem level (Eijsackers et al. 2008 ). Therefore, in an ideal Risk Assessment approach
the ecosystem is considered from a holistic perspective , that is, as the whole system
of mutually dependent organisms and abiotic parameters with regard to the whole
series of Ecosystem Services.
Another complicating factor is that there are different stakeholders with regard
to the soil ecosystem, who have different interests in the way the soil ecosystem
functions. In other words, there is no general interest in, and not one ideal state
for the soil ecosystem. This is another challenge for decision-makers in deciding
which of the various preferences are to be adopted, see Rutgers ( 2008 ) who showed
that different stakeholders in the Hoeksche Waard in the Netherlands have different
preferences.
Many different Ecological Risk Assessment tools are used around the world for
similar purposes. Therefore, Swartjes et al. ( 2008 ) made the case for harmonisation,
that is, improving the international consistency in the technical parts of Ecological
Risk Assessment procedures, at least at the European level.
13.5.2 Risk Characterisation
As explained in Section 1.5.3 , from a more general Risk Assessment perspective,
Risk Characterisation could be preceded by two steps, namely, the exposure assess-
ment (representing 'chance' in Risk Assessment terms) and the Hazard Assessment
(representing 'effect' in Risk Assessment terms). However, in Ecological Risk
Assessment these steps are often combined. The reason for this is that there are
no (or fewer) ethical obstructions, as opposed to Human Health Risk Assessment,