Human Exposure Pathways - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 461

11.2.2.3 Representative Concentration in Vegetables

To be able to determine the representative concentration in vegetables, the most
relevant vegetables must be selected. For site-specific Risk Assessment it is possible
to focus on the vegetables that are actually growing on the specific site at the moment
of the assessment. However, this assumption may not be appropriate or practical, for
the following reasons:

• These vegetables are not always appropriate for the long term representative

concentration, because the type of vegetables might change every few years.

• On many contaminated sites no (representative) vegetables are present at the time

when the assessment is made.

In addition, Risk Assessments are often designed to take into account the pos-
sibility of growing vegetables without experiencing unacceptable adverse effects
on human health. This requirement implies that, independent of the vegetables
currently growing on the site, attention should be focused on a representative con-
sumption pattern. For the Netherlands, for example, relevant vegetables are potato,
carrot, beet, radish, onion, tomato, cucumber, cauliflower, cabbage, lettuce, spinach,
endive, french bean, string bean, nave beans, kidney beans and rhubarb. Other edible
vegetables in the Netherlands are asparagus, leek, celery, brussel sprouts, eggplant,
okra, green pepper, pod, pea, marrow, lentil, courgette, maize, corn and broccoli.
Obviously, relevant vegetables significantly vary in different regions in the world.
Note that the calculation of the representative concentration in vegetables offers
more flexibility in the choice of vegetables than field measurements. In the latter
case, there is no other option than focusing on the type of plant (vegetable or non-
vegetable) that is available, unless vegetables are planted and grown specially. When
there are no vegetables at all, representative vegetable concentrations can be calcu-
lated. If measurements are necessary, for example to take some special site-specific
factors into account, and there are no vegetables present, measurements of non-
edible plants can be made, assuming that uptake in non-edible plants is related to
that in vegetables, or again, vegetables may be grown specially for measurement.

11.2.3 Mathematical Equations

11.2.3.1 Principles

As an example of quantifying exposure through vegetable consumption, the pro-
cedure used in the Netherlands is described. This procedure could, however, be
used universally. In a general form, the exposure through vegetable consumption
is calculated as follows:

Q vegetable i ×

C vegetable i × f home - grown × f bioavailability

Exposure vegetables =

W

(11.1)