Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 32

to joints are possible. Clearly, we are prepared to take some of these risks, since
these activities provide us with evident advantages. Some examples of imposed
risks are living in polder regions beneath sea level, protected by dunes and dikes, the
threat of natural catastrophes in hurricane-prone areas of the world and of terrorist
attacks.
Risks from contaminated sites typically are in the category of imposed risks:
humans can only avoid, or at best reduce the risks, by adapting their lifestyle or, in
the most extreme case, by moving to a place where the soil has not been impacted by
soil contamination. From the perspective of Risk Assessment, it is very important
to realise that risk is not necessarily a bad thing. Being at risk is part of our life;
many risks will never impact human health, and there are many risks we are not
even aware of.
When contaminants are present in soil there is a risk by definition, since there
is 'a probability' (the chance, although miniscule at very low concentrations, that
human beings or soil organisms are exposed to these contaminants) and 'an effect'
(impact on human health or ecosystem health, when contaminants indeed intrude on
humans or soil organisms). The whole idea behind Risk Assessment is not to find
out whether there are risks, but to investigate whether or not the risks are accept-
able . Nevertheless, risk assessors often use the phrase 'no risks' when in fact 'no
unacceptable risks', or more concretely 'acceptable risks' is meant. Often, regula-
tors or stakeholders seduce the risk assessor into using the 'no risks' qualification,
since the 'no unacceptable risk' qualification (double denial), or 'acceptable risks',
is more difficult to interpret and often provokes further discussion.
Risk Assessment can also be used to support the optimal allocation of financial
resources in contaminated sites projects.
1.5.3 Procedure
Risk Assessment (aka: Risk Analyses) is a process which serves the purpose of
examining risks and, when possible, quantifying risks. It is an old concept. Risk
Assessment can almost be considered as a science unto itself. It is used in widely
differing disciplines such as environmental engineering, the design of building con-
structions, financial impact assessments or in the military. Analogous to risks, we
are dealing with Risk Assessment daily, mostly without realising it. When a person
crosses the road, for example, that person makes a judgement on the chance of being
hit by a passing vehicle and the following consequences.
The Risk Assessment framework is illustrated by the light-shaded boxes in
the contaminated site management framework, in Fig. 1.3 . The first step in the
Risk Assessment framework includes two different activities, namely, the Exposure
Assessment (aka: dose assessment) and the Hazard Assessment (aka: effect assess-
ment), mainly used in Human Health Risk Assessment. Conventionally, the deter-
mination of exposure is performed for human beings or larger animals, and not so
much for smaller soil-dwelling organisms. Ideally, the amount of a contaminant that
reaches the blood stream (in case of systemic effects, i.e., related to effects in the
whole body after systemic circulation and, hence, absorption and distribution in the