Pragmatic Approach for Health Risk Assessment of Bauxite Tailing Waste Materials - Environmental Contamination: Health Risks and Ecological Restoration - page 92

Bauxite.is.screened.and.washed.after.mining,.in.order.to.remove. organ-
ics.and.under-.or.over-sized.ore..This.ore.extraction.process.generates.tail-
ings.predominantly.comprised.of.over-.and.under-sized.bauxite,.which.may.
constitute.up.to.30%.of.the.mined.ore.tonnage..Tailings.dams.are,.therefore,.
required.to.be.expanded.as.a.routine.part.of.the.mining.process..Like.most.
mining.operations,.including.dam.expansion,.there.will.be.occasions.when.
elevated.levels.of.dust.occur..A.key.driver.for.this.study.was.the.complaints.
raised. by. local. residents. living. in. closer. proximity. to. such. a. bauxite. stor-
age.facility.on.account.of.dust.fall-out.and.chemical.exposure..In.addition.to.
the.harmful.effects.of.dust.particulates.on.human.health,.some.metals.and.
metalloids.can.also.cause.adverse.health.effects.if.the.exposure.is.excessive,.
particularly.in.the.long.term..This.study.is.aimed.to.identify.and.prioritize.
potential.environmental.hazard.that.may.exist.at.a.bauxite.tailings.storage.
facility,.as.part.of.an.overall.effective.management.strategy.
Criteria.for.the.rehabilitation.of.mine.sites.in.Australia.have.become.more.
stringent,. given. the. increasing. awareness. of. potential. detrimental. envi-
ronmental. effects. caused. by. exposure. to. metals. and. metalloids. that. form.
part.of.mine.waste..Relevant.to.this.report.under.the.risk.assessment.frame.
(enHealth.2004),.we.will.evaluate.all.the.pathways.that.could.lead.to.expo-
sure.to.bauxite/soil.waste.
Where. there. are. no. speciic. health. investigation. levels. (HILs). for. mined.
land,.NEPM.guideline.values.exist.for.soil..EPHC.(the.Environmental.Health.
Council,.Australia).has.set.the.National.Environmental.Protection.Measure.
(NEPM).for.health-based.investigation.levels.(HIL).in.soil.for.residential.set-
tings.(NEPC.1999);.the.investigation.involves.detecting.metal.content.in.soil,.
including.detection.of.metals.such.as.arsenic.(As).(100.mg/kg),.beryllium.(Be).
(20.mg/kg),. cadmium. (Cd). (20.mg/kg),. chromium. (Cr III ). (12%),. chromium.
(Cr VI ). (100.mg/kg),. cobalt. (Co). (100.mg/kg),. copper. (Cu). (1000.mg/kg),. lead.
(Pb). (300.mg/kg),. manganese. (Mn). (1500.mg/kg),. mercury. (Hg). (15.mg/kg.
inorganic.mercury),.nickel.(Ni).(600.mg/kg),.and.Zinc.(Zn).(7000.mg/kg),.and.
reported. urban. background. level. for. vanadium. (V). (20-500.mg/kg). (NEPC.
1999).. The. NEPM. guideline. recommends. that. further. investigation. be. con-
ducted.if.total.elemental.concentration.in.soil.exceeds.the.HIL..In.the.absence.
of.site-speciic.bioavailability.data,.it.is.usually.assumed.to.be.100%.for.risk.
assessment.purposes..The.advantage.of.using.site-speciic.bioavailability.data.
is.that.they.can.be.used.for.a.more.reined.risk.assessment.(Ng.et.al..2010).
For. risk. assessment,. if. the. bioavailability. of. a. contaminant. is. unknown,.
then. the. standard. precautionary. practice. encourages. the. use. of. 100%. bio-
availability..This.is.recognized.as.a.very.conservative.approach..A.realistic.
risk-based.approach.is.to.measure.bioavailability.(BA).or,.at. the.very. least,.
the.bioaccessibility.(BAC).of.the.metal.of.interest..The.concept.of.BA.and.BAC.
is.discussed.in.the.following.
The.bioavailability.of.heavy.metals.and.metalloids.from.contaminated.land.
has.been.assessed.using.mammals,.including.rodents.(Ng.and.Moore.1996,.
Ng. et. al.. 1998),. meadow. voles. (Pascoe. et. al.. 1994),. dogs. (Groen. et. al.. 1994),.