Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 50

Worldwide the Soil Quality Standards used differ to a large extent. This is
partly due to differences in the purpose of the Soil Quality Standards, but the
technical frameworks also show many differences. Provoost et al. ( 2006 ) com-
pared Soil Quality Standards for eight metals and metalloids, from Canada,
Flanders (Belgium), France, Germany, the UK, the Netherlands, Norway, Sweden,
Switzerland and the USA. For most contaminants they found differences between
the highest and lowest value of more than a factor of 1000. They concluded that
some of these differences could be explained by political differences, such as the
choice of protection targets and risk levels. Some of the other differences between
Soil Quality Standards, however, are explained by technical/scientific differences
between the procedures used in the different countries. Swartjes and Carlon ( 2007 )
came to similar conclusions for Soil Quality Standards used in 16 European coun-
tries. They found even higher differences for organic contaminants. Swartjes ( 2007 )
concluded that differences between seven European exposure models, important
instruments in the derivation of human health-based Soil Quality Standards, can
result in widely different risk appraisals for the same exposure scenarios, espe-
cially for contaminants that are mobile and even more for contaminants that are
volatile. Therefore, the need for a higher consistency of Risk Assessment tools is
acknowledged in Europe (Swartjes et al. 2009 ).
1.7.3 Measurements
Measurements in contact media can significantly improve the quality of a site-
specific Risk Assessment. The kind of measurements that are possible and the
benefits of these measurements vary. In this section, a general view concerning
measurements in contact media will be given. In the introductionary chapters on
Human Health Risk Assessment (see Chapter 6 by Swartjes and Cornelis, this
topic), Ecological Risk Assessment (see Chapter 13 by Swartjes et al., this topic)
and Groundwater-related Risk Assessment (see Chapter 17 by Swartjes and Grima,
this topic) the most important measurements are described in more detail.
First, direct input parameters could be measured, such as the concentration in
human blood or body tissue (Human health Risk Assessment), or the number of
earthworms in soil (Ecological Risk Assessment). Second, basic input parameters
could be measured, such as the concentrations in soil compartments, or in contact
media. Third, s upportive input parameters could be measured, such as soil proper-
ties or input parameters that relate to long-time human behaviour, if relevant for the
site over the relevant time span.
Measuring of supportive, basic or direct input parameters have both advantages
and disadvantages. Generally speaking, the reliability of the assessment of the actual
Risk Assessment improves when more supportive measurements are available, even
more so when basic input parameters are measured and the most often when direct
measurements are performed. The disadvantage, however, is that measurements are
expensive and generally more expensive in the order of supportive, basic and direct
input parameters, and, therefore, not always suited for routine Risk Assessment.