Risk Assessment for Arsenic Exposure from Drinking Water in Vietnam

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Risk Assessment for Arsenic Exposure from
Drinking Water in Vietnam

• Van Anh Nguyen, Sunbaek Bang, Kyoung-Woong Kim
• Soil Environmental Laboratory
• Gwangju Institute of Science and Technology,
  Korea

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Content

• Arsenic general information
• Background of Vietnam
• Arsenic risk assessment in Vietnam through the
  drinking pathway
• - Hazard identification
• - Exposure assessment
• - Risk assessment
• Toxic risk assessment
• Cancer risk assessment

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Arsenic general information

• Arsenic (As) is a metalloid element in group Va
  of the periodic table
• Arsenic can cause both acute and chronic
  poisoning (IPCS INCHEM http//www.inchem.org/docum
  ents/ehc/ehc/ehc018.htmSectionNumber1.1)
• Arsenic is categorized by the USEPA as a
  multi-site human carcinogen through the drinking
  water pathway (National Research Council, 2001)
• Vietnamese standard of 10 µg/L for arsenic in
  2002 (TCVN.2002)

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Background of Vietnam

• Population in Vietnam 82, 032, 300
• Population in Ha Nam Province 820,100 (General
  statistic office of Vietnam http//www.gso.gov.vn/
  default.aspx?tabid427idmid3)
• Average rate using groundwater 30 in the whole
  country 70 in suburban areas (UNEP-RRC.AP,
  Vietnam environment monitor 2000, ISBN
  92-807-2013-9)
• First Official Documentation of Arsenic
• Poisoning
  1999

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Hazard identification

• Groundwater was used since 1995 (Chander et.al.,
  2004)
• Significant levels of arsenic in groundwater
  from various tube-wells in Ha Nam (Chander
  et.al., 2004 Nguyen, 2004)
• Significant skin cancer rate was observed 0.15
  in Vinh Tru, 0.1 in Bo De, 0.05 in Hoa Hau
  (Dang et. al., 2004)

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• Target areas

Ha Nam Province- Vietnam (http//www.hanam.gov.vn)
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Groundwater usage in target area
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Arsenic concentration in groundwater
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Arsenic concentration in groundwater
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Hazard identification

• Arsenic accumulation in human hair samples

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Hazard identification

• Significant monotonic relationship between
  arsenic concentration in hair and groundwater
  samples
• Arsenic in groundwater partly caused arsenic
  accumulation in human body

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Exposure assessment

• ADD Cwater IRwater Cveg IRveg Cmeat
  IRmeat EF
• ED / AT BW
• ADD average daily dose from ingestion
  (mg/kg-day)
• Cx Arsenic concentration in water, in
  vegetable, in fish (mg/L or mg/kg)
• IRx Water ingestion rate (L/day) (assumed
  value)
• EF exposure frequency (days/year) (assumed
  values)
• ED exposure duration (years) (assumed value)
• AT averaging time (days) - Life time (assumed
  value)
• BW body weight (kg), (assumed value)

(USEPA, http//www.epa.gov/iris/subst/0278.htmcon
oral )
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Exposure assessment
The maximum ADD0.0037 mg/kg-day The average
ADD 0.0025 mg/kg-day
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Risk assessment

• Toxic risk assessment
• Hazard Quotient (H.Q.)
• H.Q ADD/RfD
• Risk is considered occurring when HQs gt 1
• Carcinogenic risk assessment
• R 1-exp(-(SFADD))
• SF slop factor

(USEPA, http//www.epa.gov/iris/subst/0278.htmcon
oral )
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Risk assessment
RfD 3.0E-04 mg/kg-day Oral Slope Factor (SF) of
1.5 mg/kg-day ( http//www.epa.gov/iris/subst/0
278.htmconoral)
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Conclusion

• Significant arsenic concentrations were found in
  groundwater in Vinh tru, Bo De, Hoa Hau, while
  those in Nhan Dao were low
• Accumulations of arsenic in human hair samples
  related to elevated arsenic levels in groundwater
  in the target areas
• Exposure to high levels of arsenic in groundwater
  can caused both chronic and carcinogenic effects
  to human health
• Carcinogenic rates were significant

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Thank you for your attention!