The Nature, Extent, Health Risks, and Treatment of MetalAffected Drinking Water in Bangladesh

1
Public Health Strategies for Western Bangladesh
that Address the Arsenic, Manganese, Uranium and
Other Toxic Elements in Their Drinking Water
Seth H. Frisbie Erika J. Mitchell Lawrence J.
Mastera Donald Maynard Ahmad Z. Yusuf Mohammad Y.
Siddiq Richard Ortega Richard K. Dunn David S.
Westerman Thomas Bacquart Bibudhendra Sarkar
2
The Problem

• The life expectancy in Bangladesh during the
  early-1970s was only 44 years.
• The infant mortality rate (0 to 5 years) was 24.
• Many premature deaths resulted from drinking
  surface water that was contaminated with bacteria.

(Photograph by Jim Monan, 1995)

• Approximately 10,000,000 tubewells have been
  installed since 1971 to supply safe drinking
  water.
• By 1995 Bangladesh had 120,000,000 people,
  approximately 97 of Bangladeshis drank well
  water, and the life expectancy had increased to
  55 years.

3
The Problem

• Chronic arsenic (As) poisoning was first
  diagnosed in 1993.
• In 1997 our team produced the first
  national-scale map of As concentration in
  Bangladeshs groundwater.
• Over 28,000,000 Bangladeshis are drinking water
  with As concentrations above the 50-µg/L national
  standard.
• Over 150,000 Bangladeshis are expected to die
  from skin, bladder, liver, or lung cancer caused
  by chronic As poisoning.

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Melanosis of the chest
Keratosis of the palms
(Photograph by Richard Wilson, 2005)
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Keratosis of the feet
Blackfoot disease
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Multimetal Health Effects

• Over 66,000,000 Bangladeshis are drinking water
  that exceeds WHO health-based guidelines for As,
  Cr, Mn, Ni, or Pb (Frisbie et al. 2002).
• Chronic As poisoning is the most significant
  health risk.

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Multimetal Health Effects

• Sb increases As toxicity and was detected in 98
  of tubewells (Frisbie et al. 2002).
• Conversely, Se and Zn decrease As toxicity and
  are often deficient in Bangladeshs diet (Ortega
  et al. 2003).
• Estimated exposures to As, Se, and Zn from
  Bangladeshs drinking water, rice, and soil.

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Project Goals

• Determine the relative distributions of As and
  other toxic elements in drinking well water from
  western Bangladesh.
• Use these distributions to evaluate, and possibly
  improve, the public health plan for this region.

10
Sample Collection

• Groundwater samples were collected from 4
  neighborhoods in western Bangladesh.
• A total of 18 random samples were collected from
  17 tubewells in each of 3 neighborhoods.
• Access was denied at 1 sampling location
  therefore, a total of 17 random samples were
  collected from 16 tubewells in the fourth
  neighborhood.

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Analysis of All Tubewells
12
Analysis of All Tubewells

• In this neighborhood-scale study and in 2
  national-scale studies of Bangladesh, As, B, Ba,
  Cr, Mn, Mo, Ni, Pb, and U were found above WHO
  health-based drinking water guidelines (BGS/DPHE
  2001 Frisbie et al. 2002).

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Toxic Effects from Exposure in Drinking Water
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Correlation coefficients (r) for the
concentration of As versus the concentrations of
toxic elements in tubewell water from each of the
4 neighborhoods in this study, the pH of this
water, the depth of these tubewells, the age of
these tubewells, and the number of users per
tubewell.
-0.19 -0.39 0.27 0.30 0.24 0.26 -0.30 0.06 0.
08 -0.03 0.01 -0.26
0.60 0.53
-0.03 0.45 -0.04 -0.24 0.39 0.47 0.34 0.09
-0.34 -0.33
0.49 0.52 -0.55
0.18 0.14 0.23 0.21 0.33 0.09 0.25 0.20 -0.18 0.1
4 -0.16 -0.14 -0.32 -0.09 0.03 -0.17
0.16 0.21 0.37 0.40 0.03 0.27 0.07 -0.19 -
0.23
0.49

• Significant linear relationships at the 99
  confidence level are shown in red and italics.
• Significant linear relationships at the 95
  confidence level are shown in white and italics.
• No significant linear relationships at either
  confidence level are shown in plain text.

1.00 0.91 0.91 0.91 0.91 0.91 0.96
1.00
1.00 0.69 0.61 -0.69
1.00 0.74 0.66
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Analysis of All Tubewells

• In this study, as the concentration of As
  increases there are statistically significant
  increases in the concentrations of B, Ba, Cr, Fe,
  Mn, Ni, Pb, Se, and Zn.

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Analysis of Tubewells with Unsafe Concentrations
of Arsenic
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Analysis of Tubewells with Unsafe Concentrations
of Arsenic

• Almost all of the home-scale drinking water
  treatment systems currently being used in
  Bangladesh have been designed to remove As, not
  these other toxic elements.
• The statistically significant increases in toxic
  elements with As suggest that these treatment
  systems should be further evaluated for the
  removal of B, Ba, Cr, Mn, Mo, Ni, Pb, and
  possibly other elements.

SONO Filter
AMAL Filter
3 Kalshi Filter
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Analysis of Tubewells with Safe Concentrations of
Arsenic
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Analysis of Tubewells with Safe Concentrations of
Arsenic

• The current practice of testing every tubewell
  for just As will not identify drinking water with
  safe concentrations of other toxic elements.

(Photograph by The World Bank Group, 2005)
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Analysis of Tubewells with Safe Concentrations of
Arsenic

• The following 3-step testing program is proposed
  to provide safe drinking water for very little
  cost and without any delay
• The toxicity and distribution of As relative to
  Mn, U, B, Ba, Cr, Mo, Ni, and Pb suggests that
  the current practice of sampling and testing
  every tubewell in Bangladesh for As to find the
  safest sources of drinking water stay as the
  highest public health priority.
• However, if a sample meets the WHO guideline for
  As, then it should be retested for Mn and U.
• If a sample meets the WHO guidelines for As, Mn
  and U, then it should be retested for B, Ba, Cr,
  Mo, Ni, and Pb.
• Finally, all safe tubewells should be used as
  public drinking water supplies. These safe
  tubewells must be periodically monitored for As,
  Mn, U, B, Ba, Cr, Mo, Ni, and Pb.

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Analysis of All Tubewells

• When the concentration of As goes from safe to
  unsafe, the of tubewells with unsafe
  concentrations of Cr, Ni, and Pb increases.
• When the concentration of As goes from unsafe to
  safe, the of tubewells with unsafe
  concentrations of Mn, and U increases.

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The Inverse Trend Between As and U

• The drinking water in these neighborhoods
  generally has unsafe levels of As and Mn (19 of
  tubewells), or U and Mn (43 of tubewells)
  however, it seldom (4 of tubewells) has unsafe
  concentrations of both As and U together.
• In Jamjami the concentration of As decreases with
  depth (p-value 0.002), and the concentration of
  U increases with depth (p-value 0.04).
• Komlapur, to some extent, also shows these
  trends.
• In contrast, Bualda and Fulbaria do not show any
  trends between As and depth, and U and depth.

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The Inverse Trend Between As and U

• Coarse grained river channel deposits at depth
  may be under oxidizing conditions that remove As
  from groundwater and release U into groundwater.

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The Inverse Trend Between As and U

• In contrast, organic-rich peat and clay,
  regardless of depth, may be under reducing
  conditions that release As into groundwater and
  remove U from groundwater.

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The Inverse Trend Between As and U

• It is important to note that in areas where
  drilling deeper tubewells may access water with
  lower concentrations of As, the water from these
  deeper tubewells may contain increased
  concentrations of U.

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The Inverse Trend Between As and U

• Despite this inverse trend, 4 of the tubewells
  in this study had unsafe concentrations of both
  As and U.
• This is important because the home-scale drinking
  water filters that are being used in Bangladesh
  may not remove U.
• Water treatment filters typically oxidize soluble
  As(III) to insoluble As(V) to remove As by
  absorption or precipitation.
• However, this oxidation may convert insoluble
  U(IV) to soluble U(VI) and potentially increase
  the U concentration of the water after treatment.
• Alternatively, this oxidation may keep dissolved
  U in the VI oxidation state and potentially cause
  no change in the U concentration of the water
  after treatment.

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Conclusions and Recommendations

• As, B, Ba, Cr, Mn, Mo, Ni, Pb, and U were found
  above WHO health-based drinking water guidelines
  in Bangladesh.
• The concentrations of B, Ba, Cr, Fe, Mn, Ni, Pb,
  Se, and Zn can increase as the concentration of
  As increases.
• In contrast, the concentration of U can increase
  as the concentration of As decreases.
• The home-scale drinking water treatment systems
  in Bangladesh have been designed to remove As.
  They must be evaluated for the removal of As, B,
  Ba, Cr, Mn, Mo, Ni, Pb, and U.

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Conclusions and Recommendations

• The current practice of testing every tubewell
  for just As will not identify drinking water with
  safe concentrations of these other toxic
  elements.
• A 3-step testing program to provide safe drinking
  water to a large number of Bangladeshis is
  proposed.

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Sources

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