Environmental Engineering Reference
In-Depth Information
Vietnam.(Berg. et.al.. 2001,.2007,.Buschmann.et. al..2007,.Nguyen.et.al..2009).
and.Cambodia.(JICA.1999,.Polya.et.al..2003)..Individuals.can.be.exposed.to.
arsenic.through.several.pathways,.but.the.most.critical.one.is.daily.diet.and.
drinking.water.ingestion..Toxicological.studies.show.that.both.trivalent.and.
pentavalent.soluble.arsenic.compounds.are.rapidly.absorbed.from.the.gastro-
intestinal.tract.and.can.be.further.metabolized..Reduction.of.As.(V).to.As.(III).
followed.by.oxidative.methylation.of.As.(III).takes.place.to.form.mono-,.di-,.
or.trimethylated.products.(Hughes.2002)..Oral.pathway.exposure.of.organic.
arsenic.compounds.is.less.toxic.since.organic.arsenicals.are.less.extensively.
metabolized.and.more.rapidly.eliminated.in.urine.than.inorganic.arsenicals.
(ATSDR. 2007,. WHO. 2004).. There. is. no. evidence. that. arsenic. is. essential. in.
human. bodies.. In. contrast,. chronic. oral. consumption. of. arsenic. is. consid-
ered.to.cause.an.adverse.impact.on.human.beings,.known.as.“arsenicosis”.
or.“arsenic.poisoning.disease.”.Arsenicosis.can.cause.skin.lesions,.pigmen-
tation.of.the.skin,.and.the.development.of.hard.patches.of.skin.on.the.palm.
of. the. hands. and. soles. of. the. feet.. Arsenic. poisoning. inally. leads. to. skin,.
bladder,.kidney,.and.lung.cancers,.as.well.as.diseases.of.the.blood.vessels.of.
the.legs.and.feet..Diabetes,.high.blood.pressure,.and.reproductive.disorders.
may.also.be.the.side.effects.of.chronic.arsenic.exposure.(ATSDR.2007,.Tseng.
1977,.WHO.2004)..In.Cambodia,.unsafe.levels.of.arsenic.in.shallow.ground-
water.were.irst.reported.by.JICA.(1999).in.its.irst.unpublished.draft.report.
named. “The. study. on. groundwater. development. in. Southern. Cambodia”.
to. the. Cambodia. Ministry. of. Rural. Development.. Consequently,. numer-
ous.studies.have.been.conducted.and.documented..Polya.et.al..(2003,.2005),.
Stanger. et. al.. (2005),. Berg. et. al.. (2007),. Buschmann. et. al.. (2007),. Quicksall.
et.al..(2008),.Sthiannopkao.et.al..(2008),.and.Luu.et.al..(2009).have.described.
the.distribution.of.arsenic.in.shallow.Cambodian.groundwater..The.chemi-
cal,.biological,.and.physical.processes.that.control.the.heterogeneous.arsenic.
distribution. in. groundwater. have. also. been. widely. studied. (Benner. et. al..
2008,.Berg.et.al..2007,.Buschmann.et.al..2007,.Kocar.et.al..2008,.Lear.et.al..2007,.
Polizzotto.et.al..2008,.Polya.et.al..2003,.2005,.Robinson.et.al..2009,.Rowland.
et. al.. 2008).. Arsenic. treatment. systems,. modiied. from. traditional. sand. il-
ters,.have.also.been.developed.to.enhance.arsenic.removal.from.groundwa-
ter. following. seasonal. and. spatial. variations. in. groundwater. composition.
(Chiew. et. al.. 2009)..In. addition,. studies. of.baseline.concentrations.of. As.in.
human.hairs,.nails,.and.urine.have.been.used.to.assess.potential.biomarkers.
of.As.exposure.(Berg.et.al..2007,.Gault.et.al..2008,.Kubota.et.al..2006,.Sampson.
et.al..2008)..The.development.of.visual.arsenicosis.symptoms.have.been.gen-
erally. assumed. to. follow. 8-10. years. of. consumption. of. water. with. unsafe.
level.of.arsenic;.however,.new.cases.discovered.in.Cambodia.have.followed.
exposure.times.as.short.as.3.years,.due.to.extremely.elevated.arsenic.levels.
(3500.μg/L),.socioeconomic.status,.and.malnutrition.(Sampson.et.al..2008)..In.
Kandal.alone,.by.using.groundwater.quality.and.population.data,.Sampson.
et. al.. (2008). have. estimated. that. 100,000. people. are. at. high. risk. of. chronic.
arsenic.exposure..The.objectives.of.the.present.study.were.(1).to.determine.
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