Environmental Engineering Reference
In-Depth Information
Fig. 23.3
A general view of the different steps to be taken in Risk Assessment
effects of contaminants and the need for remediation. These model conclusions can
be substantiated by actual measurements of exposure or even epidemiological data.
In theory the following assessments are possible:
•
Qualitative information about the history of a site which is assessed by experts.
•
Results from chemical analyses of soil and groundwater samples are compared
with soil and Groundwater Quality Standards.
•
Results from chemical analyses of soil and groundwater samples are used to
compute exposure with exposure models. Exposure is than compared with toxi-
cological references to allow conclusion about risk for human health or ecological
functions.
•
Exposure can be measured instead of estimated with models. Results from these
measurements can be compared with toxicological references to allow conclusion
about risk for human health or ecological functions.
•
Measurement of exposure can also be used as input to a toxicological dose
response model.
•
Adverse effects can be assessed by epidemiological studies at the site.
In general, the less prediction the more reliable is the assessment, but the more
difficult is the investigation. This trade-off could lead to a system of assessment
methods with various levels of sophistication. However one should be aware that
the traditional investigation protocols that have been adopted in various national
contaminated site policies do not sufficiently recognise the trade-off between cost
of investigation and the level of detailed information needed to make a deci-
sion. Usually a fixed sequence of investigations seems to be mandatory. Historical
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