Human Exposure Pathways - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 459

CSOIL exposure model (Brand et al. 2007 ; Van den Berg 1991 / 1994 / 1995 ), the
UK CLEA exposure model (DEFRA and EA 2002 ), the French INERIS' expo-
sure model (INERIS 2003 , 2009 ), the Swedish model for the derivation of Soil
Quality Standards (Naturvårdsverket 2009 ), and the Californian CalTOX exposure
model (CalTOX, University of California 1993, California Department of Toxic
Substances Control 2009 ). Moreover, calculated exposure through vegetable con-
sumption is included in almost all human health-based Soil Quality Standards,
worldwide. For the derivation of the human health-based Soil Quality Standards in
the Netherlands, for example, exposure due to vegetable consumption is important
for all metals (Lijzen et al. 2001 ): the contribution of exposure due to vegetable con-
sumption to total exposure is more than 90% for cadmium and cobalt and between
80% and 90% of the total exposure for copper, mercury, molybdenum and zinc.
Exposure through vegetable consumption also contributes a large fraction of the
total exposure for several organic contaminants (Lijzen et al. 2001 ): over 90% for
several aromatic contaminants (phenols, catechol, resorcinol and hydroquinone),
for some chlorinated contaminants (hexachlorobenzene, pentachlorophenol, several
PCBs, chlorophenols) and for several pesticides (DDT, DDE, aldrin, carbofuran,
propoxur, atrazine, di(2-ethylhexyl)phthalate). For many dioxins this contribution is
close to 80%.
Although the same procedures for Risk Assessment generally apply to crops
grown on agricultural sites, this section does not primarily relate to Risk Assessment
for this land use. The reason for this is that agricultural produce usually is distributed
widely, and vegetables from a contaminated site will be distributed together with
vegetables from other sites. Therefore it is unlikely that one person will consume
a large fraction of their vegetables from a single contaminated agricultural source.
Moreover, contamination of metals, pesticides and nutrients at agricultural sites is
often a matter of controlling the addition of contaminants to the site (rate of fer-
tilizer, pesticide and nutrient application, respectively), rather than a question of
remediation of contaminated land.
The theory exposed in this chapter, however, is fully applicable to assess the
human health risks in the framework of Food Safety.

11.2.2 Conceptual Model

11.2.2.1 Principles

The calculation of exposure through the consumption of vegetables is performed in
two stages:

• the calculation of contaminant concentrations in the edible parts of vegetables;

• the calculation of human exposure through consumption of contaminated

vegetables.

The calculation of contaminant concentrations in the edible parts of vegetables,
the representative concentration in vegetables, is the combined result from uptake,