Environmental Engineering Reference
In-Depth Information
Table 10.1 Summary of
findings on blood lead levels in drinking water in publications dating
before 2000
Author/year
Range of lead ingested by
Contribution to BLL
Adults
Children
Elwood et al.
(
1984
)
1 mg
4.9 and 5.5
µ
g/dL
Lacey et al.
(
1985
)
1 mg/L
0.62 mg/L
10
µ
g/L
Bois et al.
(
1989
)
Up to 7 percent of
BLLs
Houk et al.
(
1989
)
50
µ
g/L
Up to 22 percent of
BLLs
Health Canada
(
1992
)
2.9
g per day of
ingested lead
µ
1.45
g are absorbed
(50 percent)
µ
Health Canada
(
1992
)
7.2
g of lead ingested
per day
µ
0.72
g are absorbed
(10 percent)
µ
pipes, pipe
fittings, and pumps contain no more than 8 percent lead while solder and
flux should not contain more than 0.2 percent lead (USEPA
2010
). The earliest
reference we found that attempts to measure lead in blood was probably by Sayre
et al. (
1974
). Since then there has been a large literature on the contribution of lead
to BLL. The
findings published prior to 2000 are summarized in Table
10.1
.
The results in Table
10.1
show an absorption rate of approximately 50 percent
for children under 2 years of age while for adults it can be as high as 22 percent.
This is consistent with
findings in many studies that children are more at risk than
adults. According to Moore et al. (
1985
), children are more at risk because as lead
in water is in soluble form, it is more readily absorbed into the bloodstream than
food containing lead; lead in food tends to combine with other elements to form
compounds that may not be easily digestible. Lacey et al. (
1985
) also support this
finding. They carried out a study in Glasgow on the effects of lead on BLLs in the
diet of 10
12-week-old infants and showed that although lead from baby food was
detectable, it was an almost insigni
-
cant amount when compared with lead ingested
from drinking water. Dust, which is a large contributor to total lead ingestion in
adults, has been shown to contribute insigni
cantly to BLLs in a statistical study
conducted by Elwood et al. (
1984
).
The relationship between lead in water and BLLs is nonlinear (Sherlock et al.
1984
and Moore et al.
1985
). This means that for every unit decrease in lead, a
more than proportionate decline in blood lead level can be achieved (Moore et al.
1985
). Other studies also examine lead exposure from drinking water and other
sources either in terms of its relative contribution (i.e. percentage of total exposure)
or its absolute contribution (i.e. exposure measured in units such as micrograms per
liter). In a study conducted in 1988 in Ontario (Canada) by Graham (
1988
), a
composite sample was used in 40 homes to determine the average amount of lead a
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