Chemistry Reference
In-Depth Information
Auto
emissions
Industrial
emissions
Crustal
weathering
Surface and
ground water
Ambient
air
Soil
Animals
Plants
Paint
pigments
Tobacco
Plumbing
Can solder
Inhaled
air
Drinking
water
Dust
Food
Man
FIGURE 1
Sources and routes of lead exposure in the general population. Modifi ed from
Skerfving (1993).
Lead carbonate hydroxide has had a widespread
use as pigment in house paint in some countries,
and weathering, chalking, and peeling paint may
cause heavy exposure (Rosner
et al
., 2005). Another
large-scale source of exposure is organolead added to
gasoline. At combustion in the engine, organic lead is
transformed into the inorganic lead oxide and is emit-
ted almost entirely as such. This causes exposure to
inorganic lead, in particular in people living in areas
with heavy traffi c. Also, industrial emissions, both
from large- and small-scale industries and producers
as well as recycling activities, may cause exposure in
neighborhood populations, and exposed workers may
bring the exposure home to their families in the form
of lead dust carried in clothing, hair, or on the skin.
the city of Lucknow, India, and Hashisho and El-Fadel
(2004) an average of 2860 ng/m
3
in urban Beirut. Simi-
lar levels (yearly mean, 2800 ng/m
3
) were observed in
the Valley of Mexico in 1987, when lead was still added
to gasoline in relatively high concentrations. Until 1997,
lead in gasoline was reduced by > 98.5%, and in 2002,
the yearly mean air-lead concentration had dropped to
70 ng/m
3
(Schnaas
et al
., 2004).
Lead exposure through inhalation, and also inges-
tion, is increased near lead-emitting industries. The
variation in air-lead levels is, of course, great. For exam-
ple, air-lead concentrations near lead acid battery recy-
cling plants in Brazil varied from 70 to 18,300 ng/m
3
(Paoliello and De Capitani, 2005). Near an Australian
lead smelter (in Port Pirie) a mean of 2150 ng/m
3
was
obtained approximately 600 m from the blast furnace
(Esterman and Maynard, 1998), and in British Columbia
a mean level of 300 ng/m
3
was found at two stations
within 2 km from the smelter, in contrast to 1100 ng/m
3
during a previous period when an older lead smelter
was in use (Hilts, 2003).
Additional inhalation exposure occurs through
cigarette smoking, although the association between
smoking and blood-lead concentration may, to some
extent, be confounded by alcohol intake (Grandjean
et al
., 1981). The lead content in a cigarette is 3-12
2.4.1.2 Inhalation
The exposure through ambient air largely depends
on any use of leaded gasoline. In areas where the air
levels of Pb are low, food is the dominating source of
lead uptake, whereas high air concentration can lead to
a situation where inhalation is of signifi cance, or even a
dominating source. Ikeda
et al
. (2000) studied the con-
tribution of lead in air at levels in the order of 75 ng/m
3
and estimated that air then contributed approximately
half of the absorbed lead in women living in Tokyo and
Kyoto. In cities where leaded gasoline is still in use, or
has only recently been phased out, mean air-lead lev-
els in the order of 200-400 ng/m
3
is common in resi-
dential areas (He
et al
., 2004; Lu
et al
., 2003). Levels are
higher in areas with heavy traffi c. For example, Kaul
et al
. (2003) reported 2000-3900 ng/m
3
in such areas in
g.
Approximately 2% of this is inhaled into the active
smoker, leaving most of the lead in the environmental
tobacco smoke. As a consequence, there is an associa-
tion between children's lead exposure and environ-
mental tobacco smoke (Baghurst
et al
., 1992; Willers
et al
., 1992). Moreover, cigarette smoking in workplaces
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