Assessing Health Risks from Arsenic Intake by Residents in Cambodia - Environmental Contamination: Health Risks and Ecological Restoration - page 70

As × IR EF ED

AT BW

× ×

w

ADD = . (5.1)

×

.

where
ADD.is.the.average.daily.dose.from.ingestion.(mg/kg/day)
As w .is.the.arsenic.concentration.in.water.(mg/L)
IR.is.the.water.ingestion.rate.(L/day)
EF.is.the.exposure.frequency.(days/year)
ED.is.the.exposure.duration.(year)
AT.is.the.average.time/life.expectancy.(days)
BW.is.the.body.weight.(kg)

ADD
RfD

. (5.2)

HQ =

.

where
HQ.is.the.hazard.quotient.(risk.is.considered.occurring.if.HQ.>.1.00)
RfD.is.the.oral.reference.dose.(RfD.=.3.×.10 −4 .mg/kg/day)

R = 1 exp( SF ADD) − − × . (5.3)

.

where.SF.is.a.slope.factor,.equal.to.1.5.mg/kg/day.
The. survey. results,. which. were. used. in. risk. computation,. are. shown. in.
Table.5.2,.and.calculated.results.of.risk.assessments.are.presented.in.Table.5.3..
Although.there.was.a.signiicantly.regional.difference.in.arsenic.uptake.of.
residents.in.each.of.the.study.areas.(Kruskal-Wallis.test,.p.<.0.0001),.no.sig-
niicant. difference. in. gender. (Mann-Whitney's. U. test,. p.=.0.06.>.0.05). and.
age. groups. (Kruskal-Wallis. test,. p.=.0.24.>.0.05). were. observed,. suggesting.
that.individual.ADD.of.arsenic.was.not.affected.by.the.different.gender.and.
age.groups.of.Cambodia.residents;.this.is.likely.due.to.the.regional.differ-
ences. of. arsenic. levels. in. groundwater.. A. positive. signiicant. correlation.
between. average. arsenic. daily. dose. (ADD). and. arsenic. levels. in. ground-
water. (As w ). (r s . (568).=.0.92,. p.<.0.01). and. a. positive. signiicant. correlation. of.
ADD.with.ED.(r s .(568).=.0.43,.p.<.0.0001).were.obtained,.revealing.that.ADD.
was.correlated.with.As w .and.ED..In.addition,.negatively.signiicant.correla-
tion.between.ADD.and.body.weight.(BW).(r s .(568).=.−0.12,.p.<.0.01).was.also.
observed.. However,. no. signiicant. association. between. ADD. and. IR. was.
found..This.is.more.likely.due.to.high.IR.in.low.arsenic.contaminated.areas.
(Table. 5.2).. Recently,. Nguyen. et. al.. (2009). reported. that. Vietnam. residents.
who. consumed. untreated. groundwater. (As.>.100.μg/L). ingested. arsenic. at.
the.rate.of.1.1.×.10 −3 .−.4.3.×.10 −3 .mg.As/kg/day..Saipan.and.Ruangwises.(2009).
used. a. duplicate.diet. study. to. show. that. Ronphibun. residents. of. Thailand.
ingested.an.average.2.1.×.10 −3 .mg.As/kg/day..The.present.study.clearly.indi-
cates.that.residents.in.the.Kandal.province.study.area.of.Cambodia.ingest.