Assessing Health Risks from Arsenic Intake by Residents in Cambodia - Environmental Contamination: Health Risks and Ecological Restoration - page 67

members. of. each. household. where. people. claimed. to. routinely. use. a. tube.
well..Hair.was.cut.from.the.nape.of.the.head,.as.near.as.possible.to.the.scalp,.
using.stainless.steel.scissors..The.collected.hair.samples.were.kept.in.labeled.
ziplock.bags.and.stored.in.darkness.until.analyses.
Sample Analyses
Groundwater.samples.from.the.Kandal.province.study.area.were.diluted.to.
analyze.the.concentrations.of.total.As,.Mn,.and.Ba..Dilution.(1:25).was.made.
for.the.inal.concentration.of.aliquots.to.meet.the.standard.calibration.curve.
as. recommended. by. ICP-MS. analytical. technique.. Dilution. was. done. with.
2%. HNO 3 . (prepared. by. 18.2. MΩ. MilliQ . deionized. water. with. 70%. HNO 3 )..
Similarly,.some.samples.from.the.Kratie.province.study.area.were.treated.in.
the.same.manner,.whereas.all.of.groundwater.samples.from.the.Kampong.
Cham.study.area.were.analyzed.without.any.treatment,.aside.from.centri-
fuging.for.total.arsenic.analysis..Hair.specimens.were.cut.into.small.pieces.
(∼0.3.cm). and. washed. with. the. recommended. method. (Ryabukhin. 1978)..
Washed.hair.specimens.were.dried.at.60°C.overnight.prior.to.digestion..Acid.
digestion. was. performed. using. a. slightly. modiied. version. of. the. method.
described.by.Gault.et.al..(2008)..Approximately.100.±.5.mg.of.two.replicated.
subsamples.of.each.dry-washed.hair.sample.were.weighed.into.acid-cleaned.
polyethylene. tubes.. One. milliliter. of. concentrated. HNO 3 . (70%. HNO 3 ). was.
added.to.each.sample,.and.tubes.were.capped.and.left.at.room.temperature..
After.48.h,.the.digestate.was.diluted.with.9.mL.of.deionized.water.and.cen-
trifuged.at.4500.rpm.for.10.min,.after.which.the.supernatant.was.transferred.
into. a. fresh. acid-cleaned. polyethylene. tube.. A. human. hair. standard. refer-
ence. material. (GBW07601). was. treated. in. the. same. manner. as. the. samples.
to.check.the.precision. and.accuracy.of.digestion.method..Calibration.stan-
dard.solutions.(0.1,.1,.5,.10,.20,.50,.and.100.μg/L).were.prepared.from.a.stock.
solution.(multielement.2A).with.the.above.2%.HNO 3 ..Concentrations.of.total.
arsenic,. manganese,. and. barium. were. analyzed. by. inductively. coupled.
plasma. mass. spectrometry. (ICP-MS,. Agilent. 7500ce).. Iron. concentrations.
were. determined. by. lame. atomic. absorption. spectrometry. (Flame-AAS,.
Perkin.Elmer.5100).
Statistical Analysis
An. SPSS. for. Windows. (Version. 13.0). was. used. to. perform. all. statistical.
analyses.on.the.data..Since.the.experimental.data.sets.were.not.normally.
distributed,.nonparametric.tests.were.performed..Kruskal-Wallis.test.was.
used. to. investigate. the. regional. differences. of. the. arsenic. and. trace. ele-
ment.concentrations.in.groundwater.(As w ),.the.average.daily.dose.(ADD).
of. arsenic,. and. the. arsenic. contents. in. scalp. hair. (As h ).. Concurrently,.
Mann-Whitney's.U.test.was.performed.to.verify.the.gender.differences.of.
ADD. and. As h .. In. addition,. Spearman's. rho.correlation. was. conducted. to.