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interpretation of risk ranking across compounds seems to be very consistent and
possibly more appropriate and precise than the interpretation of quantification of
ecological risks at the level of HC5-NOEC in terms of impacts (as treated in the val-
idation study section). The ranking of contaminants with respect to their potential
environmental risks appears rather robust.
14.6.2 SSDs and Ranking Sites
For the other use, the X
Y read-off, one can assess the potential of contaminated
soils to affect test species assemblages (PAF) or the probability that a randomly
selected test species is affected (PES). If one would consider a suite of contami-
nated sites (such as a suite of contaminants), one can predict the fractions of test
species that would be affected in those soils. When re-thinking the conceptual
meaning of the output as obtained, the output in fact provides an
ecotoxicological
“ranking of the contaminated soils (based on toxic pressure quantification, through
PAFs)”, in the sense that the higher the estimated PAF or PES, the more toxic a
soil is for tested soil organisms (Klepper et al
.
1998
),
and probably also for natural
species assemblages when exposed in such a soil.
Again, one could think of one
or two contaminated sites being the benchmarks for comparative ranking purposes
(“this site is three times more hazardous than benchmark site X”), but there may
be practical problems in selecting such benchmarks. In the Section on validation,
Fig.
14.5
showed how
sites
are ranked regarding the relative expected impacts of
site contamination, like the contaminant ranking of Fig.
14.6
.
→
14.6.3 SSDs, Rankings and Weighting in SSDs
In ranking compounds or sites, one should acknowledge here that one treats all
species as equal points in SSD models. Some authors have proposed weighted SSD
modeling to account for differences in ecological or societal importance of species
(see Section
14.8.2
). The outcome of the simple ranking with SSDs might change
if valued species are weighted. In other words, a ranking of sites with unweighted
SSDs ranks the array of sites according to only their potential to affect the species
in the data set of tested species (the Hazard Potential interpretation
sensu stricto
).
14.7 SSDs and Cost Effectiveness of Environmental Management
Environmental management is often expensive.
Preventing soil contamination using Criterion Assessments may imply major
costs, e.g. when the environmental impacts of newly produced contaminants (like
pesticides) are high. Compounds might be banned when expected risks are too high,
while use limitations may in some cases be prescribed to keep soil concentrations
below the soil quality standard. Banning a pesticide implies that the multi-year
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