Environmental Engineering Reference
In-Depth Information
When. considering. other. sources. of. Al. intakes,. food. will. account. for. an.
intake. of. 2.4.mg. Al/day. (i.e.,. 0.034.mg/kg. b.w./day,. assuming. 100%. bio-
availability);.2.L.water.consumption.per.day.with.a.3%.bioavailable.Al.will.
account.for.a.daily.intake.of.Al.at.6.μg/day..Clearly,.the.major.source.of.Al.
intake. is. food. and. not. the. dust.. If. one. adds. all. sources. to. the. aforemen-
tioned. exposure. routes. to. dust,. the. total. intake. per. day. (2.444.mg). is. still.
much.lower.than.the.TDI.of.70.mg/day.(or.1.mg.Al/kg.b.w./day.for.an.adult).
with.a.HI.of.0.035.
Similarly,.for.a.young.child.of.14.kg.b.w..the.equivalent.TDI.of.14.mg.of.Al.
from.all.exposure.routes.is.allowed..Children.breathe.12.m
3
/day.and.ingest.
100.mg.soil/day.via.hand-to-mouth.activity.(NEPC.1999)..The.absorbed.daily.
intakes. of. Al. from. dust. ingestion. and. dust. inhalation. were. calculated. to.
be. 144.8. and. 1.14.μg,. respectively,. with. a. HI. of. 0.01. (a. safety. factor. of. 96)..
Assuming. a. total. Al. dietary. intake. for. a. child. is. 50%. of. that. of. an. adult.
(1.2.mg. Food. Al,. 0.003.mg. water. Al),. the. HI. would. be. 0.096.. It. can. be. con-
cluded.that.the.risk.of.Al.due.to.its.presence.in.bauxite.dust.is.low.
Vanadium
Mild. respiratory. distresses,. such. as. cough,. wheezing,. chest. pain,. runny.
nose,. or. sore. throat,. have. been. associated. with. acute. V. exposure.. In. one.
case. study,. 0.06.mg. V/m
3
. as. vanadium. pentoxide. induced. coughing. and.
mucus.formation..Based.on.the.0.06.mg.V/m
3.
and
.
a.safety.(uncertainty).fac-
tor.applies,.the.MRL.(minimum.risk.level).is.2.μg/m
3
.(ATSDR.1992)..Factory.
workers.exposed.chronically.to.V.dusts.complained.of.nausea.and.vomiting..
Exposure.to.vanadium.via.inhalation.could.be.considered.to.be.more.signii-
cant.than.acute.oral.exposure..For.this.reason,.we.will.focus.on.this.route.of.
exposure,.with.special.reference.to.PM
10
.vanadium.concentrations.as.found.
during.this.study.
PM
10
. vanadium. ranged. from. 134.4. to. 254.7.mg/kg. in. the. bauxite. tailing.
ine.dust,.with.the.highest.concentration.found.in.the.west.dam.(SE.and.NE).
samples..Assuming.PM
10
.is.in.the.upper.end.of.NEPM.value.of.50.μg/m
3
.and.
the.dust.has.the.highest.concentration.of.255.mg.V/kg,.the.HI.for.vanadium.
exposure.would.be.0.015.when.compared.with.the.MRL.as.shown.as.follows:
255 mg/kg
=
µ
255 g/g or 255 ng/mg or 255 pg/ g
µ
.
3
3
3
g/m
3
.
V
=
5 g/m 255 pg/ g 12 75 pg/m or 12 75 ng/m or
0
µ
×
µ
=
,
0
.
0 0
.
13
µ
air
3
3
HI
=
0 013 g m 2 g m 0 015 a safety factor of 154
.
/
/ /
=
.
(
)
m
m
.
We. conclude. that. there. is. a. safety. factor. of. 154. times. when. compared.
to. the. MRL. even. assuming. that. vanadium. in. the. dust. is. more. soluble.
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