Environmental Engineering Reference
In-Depth Information
Table 11.6
Intake rate of tap water for children in Sweden
95th percentile
intake of tap water
[L
Age
[years]
Average intake of
tap water [L
d
−
1
]
d
−
1
]
·
·
4
0.131
0.375
8
0.152
0.152
11
0.179
0.575
Livsmedelsverket (
2006
)
Data from the Swedish Food Administration (Livsmedelsverket
2002
) show that
the WHO-values for adults correspond approximately to the 95th-percentile for
water consumption. The average intake of coffee, tea and water in Sweden is 1.2
L/d for women, of which 0.6 L are tap-water. The 95th percentile was 2.4 L/d. For
men, the average intake was 1 L/d, of which 0.3 L were tap water. The 95th per-
centile was 2 L/d. For children, the average intake of tap water and 95th percentiles
(Livsmedelsverket
2006
) are shown in Table
11.6
. These data do not include the
intake of water in the form of soup and other foodstuffs. Therefore, the WHO-value
of 1 L/d is appropriate for a high, but realistic, consumption of drinking water for
children.
11.4.3.2 Data for Volatilisation and Dermal Pathways
In order to calculate exposure due to volatilisation of contaminants in domestic
water, parameters are needed for volatilisation (usually not scenario specific) and
for the exposure (scenario specific). The volatilisation parameters are model spe-
cific and can include data for the mass transfer coefficients for the gas and water
phase respectively and the molecular weight of the contaminant, shower water tem-
perature and original water temperature, droplet size and falling time. The exposure
parameters consist of the inhalation rate and the exposure time. Standard parameters
are found in US EPA (
1991
), Brand et al. (
2007
) and OVAM (
2004
).
Data on exposure parameters and methods to estimate dermal uptake can be
found in US EPA (
2004b
), Brand et al. (
2007
) and OVAM (
2004
).
11.4.4 Reliability and Limitations
Exposure estimates based on contaminant concentration in tap water are relatively
reliable. Average consumption of drinking water is well known although there is a
large variability between individuals. Also, the volatilisation from domestic water
can generally be well described by models. The models are usually derived from
observation of radon emissions from domestic waters for which there exists large
amounts of data compared to what is available for ordinary soil contaminants.
However, variations may be large in human behaviour (duration and frequency of
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