Bringing Sustainable Management of Contaminated Sites into Practice – The Role of Policy and Regulations - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 1034

(1) Politicians have to consider the perception of non-experts. The perception of the
public might frame the questions to be asked during an assessment. A formal
scientific assessment may not fully answer the political questions.
(2) If scientific assessments are made very detailed and very specific, they almost
dictate the decision to the risk manager. On the one hand this simplifies and
accelerates the decision-making, while on the other hand the autonomous role
of the decision-maker is reduced. This trade-off calls for a dynamic interplay
between assessment and management of risk.
(3) Whether a certain risk is acceptable is not a scientific issue but an individual
choice, if it concerns a single person, or a political setting if a large group
of people is concerned. Scientists can assess the likelihood of occurrence of
an adverse effect. However, if they act according to the scientific tradition
that there is no effect unless it is proven beyond all statistical doubt, Risk
Management will not be very protective. Risk Assessment will, on the other
hand, fail to come to a decision, if every kind of effect shall be excluded.
According to Shrader Frechette ( 1996 ), scientists involved in Risk Assessment
must avoid false positive conclusions about risk as well as false negative
ones.
Risk Assessment usually should result in a decision: “risk” or “no risk”. In
many cases however, the decision between these two opposite endpoints is dif-
ficult and costly. The assessor experiences, often for a long time, a situation
where a risk cannot be proved to be present or to be absent with a high degree
of probability. The less doubt is desired about the decision, the more effort is
necessary. This leads to another question in Risk Assessment: How much doubt
is tolerable?
(4) Risk Assessments can involve statements about complicated and poorly under-
stood phenomena. Even for situations with adequate dose-effect relationships,
a no-effect level (or negligible risk level for carcinogens) may be estimated, but
cannot be verified in practice. To detect low levels of risk, very large sample
sizes are needed. Scientific proof is possible in theory, but not in practice. This
problem has been labelled as “trans-scientific” by Weinberg ( 1972 ).
If a Risk Assessment is hampered by lack of information, large uncertainties and
numerous trans-scientific questions, it may not be very powerful in helping to make
decisions. Some people might claim: it is the best we have, because it is the only
way to make an objective decision. Others are more sceptical: wrong decisions are
wrong even if objective! It is clear that Risk Assessment cannot solve all problems in
decision-making in uncertain situations, which may lead to provocative statements
like O'Brien ( 1994 ): “Scientists should move away from the hubris of assimila-
tive capacity estimation and Risk Assessment to the wisdom of a precautionary
orientation”. One might also say that if scientific Risk Assessment is hardly pos-
sible, a more intuitive political perception of risk (like the precautionary principle)
might provide better guidance in decision-making. Therefore, a modern view on
Risk Assessment does not separate Risk Assessment from Risk Management. Risk