Human Exposure Pathways - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 466

the concentration of organic contaminants in vegetables is based on an adapted
Trapp and Matthies model (see Chapter 9 by Trapp and Legind, this topic). In this
model the partitioning of contaminants between pore water and roots and the sub-
sequent translocation to the upper plant parts is calculated, in order to estimate the
contaminant concentration in the above-ground plant parts.
Finally, in Tier 3, a standardised measurement protocol has been developed. This
protocol allows for sampling of a significant number of representative vegetables in
the field, for which the edible parts of the plants are treated in the laboratory in anal-
ogy with standard kitchen preparation. Subsequently, the measured concentrations
can be used in an exposure calculation or, when appropriate, compared to acceptable
concentrations in vegetables.
11.2.6 Further Considerations
To assess the risk due to vegetable consumption it is essential to include exposure
due to soil ingestion (see Chapter 7 by Bierkens et al., this topic) in most cases,
because hand-mouth contact is relatively intensive during gardening, also for adults.
People with “Vegetable gardens” often consume more vegetables than the general
population. In Swartjes et al. ( 2007 ) a 10% higher consumption rate of potatoes
was derived for this group of people, in the Netherlands. For most vegetables the
consumption rate for people with gardens is approximately 70% higher for adults
and schoolchildren and 20% higher for babies and pre-school children.
In many developed countries, a relatively high percentage of vegetables gardens
are used by immigrants. In these cases, the quality of a Risk Assessment is
improved when the vegetable package relates to the specific vegetables that these
immigrants grow.
11.2.7 Reliability and Limitations
In Swartjes ( 2007 ) it was demonstrated that the variation in calculated exposure
through vegetable consumption between seven European models was substantial,
i.e., substantially higher than the variation in calculated exposure through soil inges-
tion, but much lower than the variation in calculated exposure through indoor air
inhalation. It is generally recognised, however, that the most uncertain aspects of
this calculation is in the assessment of the representative concentration in vegetables
(see Chapter 8 by McLaughlin et al., for metals; Chapter 9 by Trapp and Legind, for
organic contaminants, this topic).
11.3 Exposure Through Consumption of Animal Products
Human exposure through consumption of animal products from contaminated sites
is potentially significant, as some contaminants (for example, dioxins, PCB) can
bioaccumulate in the food chain (see Fig. 11.2 for the transfer of contaminants into
a cow as an example).