Title: The Nature, Extent, Health Risks, and Treatment of Metal-Affected Drinking Water in Bangladesh
1Public 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
2The 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.
3The 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.
4Melanosis of the chest
Keratosis of the palms
(Photograph by Richard Wilson, 2005)
5Keratosis of the feet
Blackfoot disease
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7Multimetal 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.
8Multimetal 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.
Metal Recommended Dietary Allowance (µg/day) Exposure from Water, Rice, and Soil (µg/day)
As Se Zn Not determined 55 11,000 200 46 7,300
9Project 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.
10Sample 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.
11Analysis of All Tubewells
Element Average Concentration (µg/L) WHO Health-Based Guideline (µg/L) of Unsafe Tubewells
As B Ba Cr Fe Mn Mo Ni Pb Sb Se U Zn 29 lt50 140 4.7 2,700 800 1.4 11 0.5 1.6 lt1 2.5 15 10 500 700 50 NA 400 70 70 10 20 10 2 NA 33 0 0 1 NA 78 0 1 1 0 0 48 NA
12Analysis 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).
13Toxic Effects from Exposure in Drinking Water
Element Toxicity
As B Ba Cr Mn Mo Ni Pb U Cancers and skin and vascular diseases in humans. Developmental and reproductive diseases in animals. Hypertension in humans. Inadequate evidence of carcinogenicity in humans. Neurological and liver diseases in humans. Osteoporosis and gout-like symptoms in humans. Skin diseases in humans. Developmental and reproductive diseases in rats. Cancer, hypertension, and neurological, developmental, and reproductive diseases in humans Kidney and bone diseases in humans.
14Correlation 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.
Element As As As As
Bualda Fulbaria Jamjami Komlapur
As B Ba Cr Fe Mn Mo Ni Pb Sb Se U Zn pH Depth Age Users
-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
15Analysis 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.
16Analysis of Tubewells with Unsafe Concentrations
of Arsenic
Element Average Concentration (µg/L) WHO Health-Based Guideline (µg/L) of Unsafe Tubewells
As B Ba Cr Fe Mn Mo Ni Pb Sb Se U Zn 84 lt50 220 9.5 7,300 870 2.0 31 1.2 2.3 lt1 0.9 21 10 500 700 50 NA 400 70 70 10 20 10 2 NA 100 0 0 5 NA 59 0 5 5 0 0 14 NA
17Analysis 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
18Analysis of Tubewells with Safe Concentrations of
Arsenic
Element Average Concentration (µg/L) WHO Health-Based Guideline (µg/L) of Unsafe Tubewells
As B Ba Cr Fe Mn Mo Ni Pb Sb Se U Zn lt7 lt50 110 2.4 400 770 1.2 1.0 lt0.2 1.2 lt1 3.2 12 10 500 700 50 NA 400 70 70 10 20 10 2 NA 0 0 0 0 NA 87 0 0 0 0 0 64 NA
19Analysis 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)
20Analysis 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.
21Analysis of All Tubewells
Element of Unsafe Tubewells if As is Safe of Unsafe Tubewells if As is Unsafe
As B Ba Cr Fe Mn Mo Ni Pb Sb Se U Zn 0 0 0 0 NA 87 0 0 0 0 0 64 NA 100 0 0 5 NA 59 0 5 5 0 0 14 NA
- 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.
22The 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.
23The 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.
24The 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.
25The 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.
26The 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.
27Conclusions 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.
28Conclusions 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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