Environmental Engineering Reference
In-Depth Information
partitioning coefficient (Kow) and the molecular weight of the contaminant. The
Dutch CSOIL model uses a single expression for all organic contaminants, while
the US Risk Assessment Guidelines for Superfund (US EPA
2004b
) uses empirical
values for inorganic contaminants and an empirical expression based on Kow and
molecular weight for the organic contaminants.
The exposure due to dermal contact further depends on the concentration in the
water, the body surface of a child/adult, the fraction of exposed skin during shower-
ing or bathing, the exposure time, the relative sorption factor and the body weight.
11.4.3 Input Parameters
11.4.3.1 Consumption of Drinking Water
The intake of drinking water depends on age, climate (intake increases significantly
at temperatures over 25
◦
C), physical activity and cultural differences. Water can
be consumed directly, in the form of other drinks (e.g., tea, coffee, soup) or indi-
rectly in connection to food preparation. Bottled water can contribute to the total
consumption. WHO's drinking water guideline values for potentially toxic contam-
inants (WHO
1993
and updates, WHO
2006
) are based on an intake of 2 L/d for an
adult weighing 60 kg, 1 L/d for children with a body weight of 10 kg and 0.75 L/d
for bottle-fed babies with a body weight of 5 kg. Children have a greater intake per
kg body weight and are more sensitive to many contaminants.
Many models, including the European model for Risk Assessment of chemicals
(ECB
2003
) and CSOIL (Brand et al.
2007
) use the drinking water consumption
rates suggested by WHO. A number of national surveys have shown that the average
intake is less than the WHO-values, though it varies widely between individuals.
In the IEUBK model for calculating the exposure of children to lead (US
EPA
2002b
), the US EPA uses age specific drinking water ingestion rates, see
Table
11.5
.
ECETOC (
2001
) recommends an average intake of drinking water of 1.1 L/d for
adults and 0.5 L/d for children in the age 1-11 years, based on UK studies.
Table 11.5
Age dependent
drinking water ingestion rates
used in the IEUBK-model
Drinking water
ingestion rate
[L
d
−
1
]
Age [years]
·
0-1
0.20
1-2
0.50
2-3
0.52
3-4
0.53
4-5
0.55
5-6
0.58
6-7
0.59
US EPA (
2002b
)
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