Arsenic in tube well water in Bangladesh: Health and economic impacts and implications for arsenic mitigation

Abstract

A national drinking water quality survey conducted in 2009 furnished data that were used to make an updated estimate of chronic arsenic exposure in Bangladesh. About 20 million and 45 million people were found to be exposed to concentrations above the national standard of 50 µg/L and the World Health Organization's guideline value of 10 µg/L, respectively. From the updated exposure data and all-cause mortality hazard ratios based on local epidemiological studies, it was estimated that arsenic exposures to concentrations > 50 µg/L and 10-50 µg/L account for an annual 24 000 and perhaps as many as 19 000 adult deaths in the country, respectively. Exposure varies widely in the 64 districts; among adults, arsenic-related deaths account for 0-15% of all deaths. An arsenic-related mortality rate of 1 in every 16 adult deaths could represent an economic burden of 13 billion United States dollars (US)inlostproductivityaloneoverthenext20years.Arsenicmitigationshouldfollowatwo−tieredapproach:(i)prioritizingprovisionofsafewatertoanestimated5millionpeopleexposedto> 200µg/Larsenic,and(ii)buildinglocalarsenictestingcapacity.TheeffectivenessofsuchanapproachwasdemonstratedduringtheUnitedNationsChildren′sFund2006−2011countryprogramme,whichprovidedsafewatertoarsenic−contaminatedareasatacostofUS) in lost productivity alone over the next 20 years. Arsenic mitigation should follow a two-tiered approach: (i) prioritizing provision of safe water to an estimated 5 million people exposed to > 200 µg/L arsenic, and (ii) building local arsenic testing capacity. The effectiveness of such an approach was demonstrated during the United Nations Children's Fund 2006-2011 country programme, which provided safe water to arsenic-contaminated areas at a cost of US 11 per capita. National scale-up of such an approach would cost a few hundred million US dollars but would improve the health and productivity of the population, especially in future generations.

Full text

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
Policy & practice
839
Arsenic in tube well water in Bangladesh: health and economic impacts
and implications for arsenic mitigation
Sara V Flanagan,a Richard B Johnstonb & Yan Zhenga
Introduction
Exposure to arsenic through drinking water sourced from
groundwater is a global public health problem that is particu-
larly devastating in Bangladesh.1,2 According to survey data
from 2000 to 2010, an estimated 35 to 77 million people in
the country have been chronically exposed to arsenic in their
drinking water in what has been described as the largest mass
poisoning in history.2,3 In rural areas, 97% of the population
relies on tube wells4 installed since the 1970s to reduce disease
from ingestion of pathogen-laden surface waters. Unfortunate-
ly, this has resulted in a population highly exposed to arsenic
but with limited means or incentives for seeking safe water
alternatives. First detected in well water in the early 1990s,
arsenic is released from sediment by biogeochemical processes
that promote reducing environments.5,6 e tube wells, aord-
ably priced at about 100 United States dollars (US$), draw
the arsenic-containing groundwater from a shallow depth of
10–70 m.3 Groundwater from depths > 150 m usually contains
less arsenic3 and can be a sustainable drinking water source.7
e health implications of chronic arsenic exposure in
such a large population are substantial.2 Between 2000 and
2003, 4.94 million tube wells throughout Bangladesh were
tested for arsenic and marked as safe or unsafe.8,9 Since then,
well switching has partially succeeded in reducing exposure.10
However, sustaining the behaviour change required for long-
term sharing of wells is dicult. Additionally, severely aected
areas have few if any safe water options and need alternative
drinking water sources. Areas showing high proportions
of unsafe wells (i.e. wells whose water contains arsenic in
concentrations > 50 µg/L, the Bangladeshi drinking water
standard) are largely the same areas experiencing the highest
arsenic concentrations (oen > 200 µg/L). is suggests that
interventions targeting areas with the highest proportion of
unsafe wells are also likely to reach the population exposed to
the highest arsenic concentrations and hence at highest risk
of experiencing adverse health outcomes.11 Mitigating the
problem of water containing high levels of arsenic requires a
sizeable investment in the water supply infrastructure. is
paper provides evidence that such investment is economically
justied when the health and economic burdens of unabated
arsenic exposure are considered.
Arsenic exposure from drinking water in
2009
e 2009 Bangladesh Multiple Indicator Cluster Survey
(MICS) included collection of drinking water for arsenic
tests from 15 000 randomized households nationwide.11 e
National Drinking Water Quality Survey report used an esti-
mated national population of 164 million to estimate that 22
million and 5.6 million people are drinking water with arsenic
concentrations > 50 µg/L and > 200 µg/L, respectively. Accord-
ing to preliminary census gures for 2011, the population of
Bangladesh is about 142.3 million. Based on this gure, the
people drinking water having arsenic concentrations > 50 µg/L
and > 200 µg/L are approximately 19 million and 5 million,
respectively. ese estimates may be revised upwards when the
nal 2011 census gure is released. e proportion of water
samples with arsenic in excess of permissible limits was found
to be lower in the MICS survey than in previous national well
surveys, which suggests important progress in mitigation
(Table 1), although dierences in sample collection (e.g. use
of household drinking water versus source water) could also
explain the dierence.11
Abstract A national drinking water quality survey conducted in 2009 furnished data that were used to make an updated estimate of chronic
arsenic exposure in Bangladesh. About 20 million and 45 million people were found to be exposed to concentrations above the national
standard of 50 µg/L and the World Health Organization’s guideline value of 10 µg/L, respectively. From the updated exposure data and all-
cause mortality hazard ratios based on local epidemiological studies, it was estimated that arsenic exposures to concentrations > 50 µg/L
and 10–50 µg/L account for an annual 24 000 and perhaps as many as 19 000 adult deaths in the country, respectively. Exposure varies
widely in the 64 districts; among adults, arsenic-related deaths account for 0–15% of all deaths. An arsenic-related mortality rate of 1 in
every 18 adult deaths could represent an economic burden of 13 billion United States dollars (US$) in lost productivity alone over the next
20 years. Arsenic mitigation should follow a two-tiered approach: (i) prioritizing provision of safe water to an estimated 5 million people
exposed to > 200 µg/L arsenic, and (ii) building local arsenic testing capacity. The effectiveness of such an approach was demonstrated
during the United Nations Children’s Fund 2006–2011 country programme, which provided safe water to arsenic-contaminated areas at
a cost of US$ 11 per capita. National scale-up of such an approach would cost a few hundred million US dollars but would improve the
health and productivity of the population, especially in future generations.
a Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, United States of America.
b Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
Correspondence to Yan Zheng (e-mail: yzheng@ldeo.columbia.edu).
(Submitted: 13 December 2011 – Revised version received: 12 August 2012 – Accepted: 20 August 2012 – Published online: 14 September 2012 )

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
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Policy & practice
Mitigation of arsenic in tube well water in Bangladesh Sara V Flanagan et al.
Modelling arsenic-related
mortality
Chronic arsenic exposure is linked to a
range of dose-dependent conditions, in-
cluding cancers of the skin, bladder, kid-
ney and lung,12–14 as well as skin lesions,
arterial hypertension and cardiovascular
disease, pulmonary disease, peripheral
vascular disease, diabetes mellitus and
neuropathy.2 In Bangladesh, the risk of
dying from ingestion of arsenic in drink-
ing water has been shown to depend on
the level of arsenic exposure.15,16 Sohel et
al. analysed survival data for 1991–2000
from a health and demographic surveil-
lance system covering 115 903 people
in Matlab (Table 2). Aer adjusting for
potential confounders such as age, sex,
education and asset score (as an indica-
tor of household wealth), they found
that arsenic exposure through drinking
water accounts for considerable excess
mortality among adults in rural Ban-
gladesh.15
e Health Eects of Arsenic Lon-
gitudinal Study (HEALS), which fol-
lowed a cohort of 11 746 people in
Araihazar subdistrict from October
2000 to February 2009,16 also showed
that arsenic exposure is associated with a
higher risk of death (Table 3). Although
both Argos et al. and Sohel et al. found
this increased risk even at low exposure
levels (10–50 µg/L), historical exposure
to concentrations > 50 µg/L arsenic may
have introduced bias.17 To reduce the
risk of bias, the population exposed to
0–10 µg/L was used as a reference group,
but because of uncertainties in lifetime
exposure history in both studies, the
dose category may have been assigned
incorrectly, especially at the lower dose.
Sohel et al. attempted to construct an
exposure history for each subject but
was unable to do so for those already de-
ceased. Additionally, Sohel et al. found
the hazard ratio (HR) to be higher for
all non-accidental deaths than for any of
the three known arsenic-related causes
of death – cancer, cardiovascular prob-
lems, infection – at an exposure level of
10–50 µg/L (Table 2),15 which suggests
that factors other than arsenic exposure
could have inuenced the ndings.
Although the HRs from these studies
are fraught with uncertainties that bear
further investigation, we used them to
estimate arsenic-related mortality in
Bangladesh because they were the best
data available.
To assess the impact of arsenic
exposure on mortality in Bangladesh,
we calculated the excess deaths from
the estimated risk of death (hazard)
among adults in each arsenic exposure
category (Table 2 and Table 3). e
MICS 2009 drinking water quality sur-
vey provided the population exposure
estimates.11 From the resulting popu-
lation attributable fraction (PAF) we
estimated the annual number of deaths
for each district by using the area’s adult
population (based on the census and the
age distribution from the Bangladesh
Demographic and Health Survey 2007)18
and an estimate of the crude death rate.
Because Bangladesh has no active vital
registry system, we used a crude death
rate for adults (> 15 years old) of 8.5
deaths per 1000 population, a gure
based on WHO mortality estimates19
and consistent with ICDDR,B Health
and Demographic Surveillance System
observations in Matlab and with crude
death rates in other countries of south-
ern Asia.
Using Sohel et al.’s HR for non-
accidental deaths, we modelled excess
deaths for all districts and arrived at
an annual total of nearly 43 000 deaths,
representing about 5.6% of all deaths,
as being attributable to chronic arsenic
exposure at current exposure levels
(Table 4). On the basis of Sohel’s cause-
specic mortality HRs, about 1 in 16
cancer deaths, 1 in 36 cardiovascular
disease deaths and 1 in 19 deaths from
infections are attributable to arsenic
exposure. We used Sohel et al.’s HR
for non-accidental deaths because
Argos et al.’s HR for the 10–50 μg/L
exposure level is implausible, since it is
Table 1. Arsenic concentration in drinking water and proportions exposed as
determined by testing during national surveys, Bangladesh
Arsenic
concentration
(µg/L)
BGS/DPHE 2000 (n = 3 534) MICS 2009 (n = 14 442)
Proportion (%) Cumulative (%) Proportion (%) Cumulative (%)
0–10 57.9 57.9 68.0 68.0
10.1–50 17.1 75.1 18.7 86.6
50.1–100 8.9 84.0 7.2 93.8
100.1–150 4.2 88.2 1.4 95.2
150.1–200 2.9 91.1 1.4 96.6
200.1–250 2.1 93.2 1.1 97.8
250.1–300 1.8 94.9 0.4 98.2
300+ 5.1 100 1.8 100
BGS, British Geological Survey; DPHE, Department of Public Health Engineering; MICS, Multiple Indicator
Cluster Survey.
Table 2. Hazard ratios (HRs) for death from arsenic exposure, by cause of death and average arsenic concentration in drinking water,
in a cohort of 115 903 people,15 Bangladesh
Average arsenic concentration
(μg/L)
HR for cause of death (95% CI)
Nonaccidental Cancer Cardiovascular Infection
< 10a1.00 1.00 1.00 1.00
10–49 1.16 (1.06–1.26) 1.10 (0.77–1.59) 1.03 (0.82–1.29) 1.09 (0.92–1.30)
50–149 1.26 (1.18–1.36) 1.44 (1.06–1.95) 1.16 (0.96–1.40) 1.30 (1.13–1.49)
150–299 1.36 (1.27–1.47) 1.75 (1.28–2.40) 1.23 (1.01–1.51) 1.51 (1.31–1.75)
≥ 300 1.35 (1.23–1.48) 1.56 (1.06–2.30) 1.37 (1.07–1.77) 1.59 (1.33–1.91)
CI, confidence interval.
a Reference category.

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253 841
Policy & practice
Mitigation of arsenic in tube well water in Bangladesh
Sara V Flanagan et al.
not signicant at the 0.05 signicance
level, is higher than for the 50–150 μg/L
exposure group, and predicts nearly
twice as many excess deaths as Sohel et
al.’s HR (Table 5). Interestingly, under
either study the excess deaths among
people exposed to arsenic concentra-
tions of 10–50 μg/L (below the national
standard) represent from 45% to 62%
of all arsenic-related deaths. However,
a proportion of the population that is
currently in the 10–50 μg/L exposure
group may have been exposed to higher
arsenic concentrations in the past and
have an increased risk of death reective
of previous rather than current expo-
sure. In light of this, we used the total
number of arsenic-attributable deaths
– about 43 000 deaths per year – for our
economic impact assessment, since it
more accurately reects total exposure,
past and present.
Economic implications
We estimated the economic losses re-
sulting from the arsenic-related mortal-
ity burden by calculating lost productiv-
ity in terms of per capita gross domestic
product (GDP). According to estimates
by the International Monetary Fund,
the per capita GDP for Bangladesh in
2009 was 1465 purchasing power parity
dollars. If we assume steady economic
growth and an average loss of 10 years
of productivity per arsenic-attributable
death, over the next 20 years arsenic-
related mortality in Bangladesh (1 of
every 18 deaths) could lead to a loss
of US$ 12.5 billion, provided arsenic
exposure (> 10 μg/L) remains the same
as in 2009. We made this estimate using
Sohel et al.’s HRs and a discount rate of
5%.20 Our assumption of an average loss
of 10 years of productivity per arsenic-
attributable death was based on lost
productivity owing to deaths from types
of cancer known to be arsenic-related
and may be a conservative assumption
because medical care capacity in Ban-
gladesh is limited. e average person
dying of cancer in the United States of
America loses 15.4 years of life and, for
the four types of cancer linked to arse-
nic exposure (skin, bladder, kidney and
lung), the average loss ranges from 11 to
18 years.2,21 Although life expectancy in
the United States is higher than in Ban-
gladesh, the proportion of time people
spend working is probably higher in
Bangladesh, so any loss of life in Ban-
gladesh would translate into a greater
reduction in lifetime productivity.
Because the loss in GDP attributable to
deaths does not take into account health
costs or other costs to society, it prob-
ably underestimates the full economic
burden. is burden can be expected to
grow as the country develops and life
expectancy rises. e morbidity burden
will also increase as diagnostic tests
improve and better treatment methods
prolong the lives of people with chronic
arsenic-related disease, and the costs of
medical care will increase in tandem.
Consequences of delaying
action
In Bangladesh, arsenic-related diseases
and deaths will increase in the future be-
cause the latency period aer exposure
lasts several decades.2 Studies on chronic
arsenic exposure in utero and in early
childhood suggest an increased risk of
fetal loss, infant death, reduced birth
weight and impaired cognitive func-
tion in children, as well as signicantly
higher risks of impaired lung function,
renal cancer and death from lung can-
cer, lung disease and acute myocardial
infarction later in life.22–26 Since an entire
generation has now grown up exposed to
arsenic, some children will become “ar-
senic orphans” as their caretakers suc-
cumb to arsenic-related diseases. ese
children may also be exposed to arsenic
themselves, which would perpetuate the
cycle of arsenic-related disease.
It is illustrative to examine the
impact of arsenic exposure on children
not yet born, whose future health will be
aected by the concentration of arsenic
in the water they begin drinking in utero,
as shown by several studies.22–27 We con-
template three scenarios for population
exposure to arsenic in concentrations
> 50 µg/L: in the rst and worst, expo-
sure is constant beginning in 2000; in
the second and best, exposure has been
eliminated by 2010; in the third and most
realistic, exposure is reduced to 13%
by 2010 (as found in MICS 2009) and
completely eliminated by 2030. How will
these exposure scenarios aect today’s
children in the future? e proportion
of eventual deaths attributable to arsenic
exposure above the national standard
in each year’s birth cohort ranges from
0% when exposure to drinking water
containing arsenic in concentrations
> 50 μg/L has been eliminated by the
respective year, to 5.8% if the exposure
level remains the same as in 2000. Over-
all, only 1.1% of eventual deaths in the
2000–2030 cohorts would be attributable
to arsenic if exposure to concentrations
> 50 µg/L had been eliminated by 2010.
However, if exposure levels throughout
2000–2030 were to remain the same as in
2000, 5.8% of all eventual deaths in the
2000–2030 cohort would be attributable
to arsenic. e most likely scenario will
lie in between: if exposure to arsenic in
concentrations > 50 µg/L is eliminated
by 2030, 2.4% of the cohort’s future
deaths will be attributable to arsenic.
In absolute terms, if about 90 million
children are born between 2000 and
2030, between 1 and 5 million of their
eventual deaths will be attributable to ex-
posure to arsenic concentrations above
the national standard, depending on the
exposure scenario. is exercise shows
that any population- level reduction in
arsenic exposure will result in decreased
arsenic-related morbidity and mortality
among children yet to be born. Similarly,
any failure to sustain progress in arsenic
mitigation will result in deaths that could
have been prevented among members of
future generations. However, because
of uncertainty and individual variation
in arsenic exposure and the latency pe-
riod before disease onset, these analyses
are qualitative and semiquantitative
predictions at best.
Table 3. Hazard ratios (HRs) for death from arsenic exposure, by cause of death and
baseline arsenic concentration in drinking water, in a cohort of 11 746 people,16
Bangladesh
Baseline arsenic
concentration (μg/L)
Cause of death
All-cause HR (95% CI) Chronic disease HR (95% CI)
< 10.1 1.00 1.00
10.1–50.0 1.34 (0.99–1.82) 1.33 (0.94–1.87)
50.1–150.0 1.09 (0.81–1.47) 1.22 (0.87–1.70)
150.1–864.0 1.68 (1.26–2.23) 1.68 (1.21–2.33)
CI, confidence interval.

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
842
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Mitigation of arsenic in tube well water in Bangladesh Sara V Flanagan et al.
Table 4. Population attributable fraction (PAF) of deaths from arsenic exposure and arsenic-attributable excess deaths (ED) per year for
different arsenic concentrations in drinking water, by district, Bangladesh, 2011
District 2011 adult
population
(thousands)
PAF
(Sohel et al.)15
PAF
(Argos et al.)16
Annual no. of arsenic-attributable ED by arsenic concentration
(in μg/L) and in total (Sohel et al.)15
ED
(Argos et al.)16
10–49 50–149 150–299 ≥ 300 Total deaths
Bagerhat 931 0.036 0.045 133 103 41 8 285 361
Bandarban 244 0.013 0.024 28 0 0 0 28 51
Barguna 562 0.003 0.005 13 0 0 0 13 23
Barisal 1459 0.019 0.031 158 24 20 40 241 392
Bhola 1120 0.003 0.006 32 0 0 0 32 59
Bogra 2147 0.022 0.034 293 90 29 0 412 619
Brahamanbaria 1789 0.090 0.116 240 373 273 485 1371 1765
Chandpura1524 0.115 0.152 77 324 461 640 1503 1976
Chittagonga4783 0.041 0.062 1140 383 98 72 1694 2514
Chuadanga 715 0.087 0.116 296 173 49 12 531 708
Comillaa3379 0.130 0.162 356 1066 1262 1064 3748 4673
Cox’s Bazar 1449 0.004 0.006 34 13 0 0 47 68
Dhaka 7564 0.020 0.026 555 435 305 0 1295 1662
Dinajpur 1892 0.007 0.013 115 0 0 0 115 212
Faridpur 1189 0.133 0.171 511 439 292 112 1354 1737
Feni 905 0.088 0.084 177 392 88 21 678 649
Gaibandha 1496 0.071 0.107 633 189 49 32 902 1364
Gazipur 2123 0.006 0.009 63 23 30 0 116 170
Gopalganj 732 0.145 0.171 223 341 267 73 904 1069
Habiganj 1312 0.089 0.115 542 356 101 0 999 1294
Jamalpur 1443 0.015 0.063 76 0 0 0 76 781
Jessore 1747 0.040 0.120 380 86 32 0 498 1785
Jhalokathi 380 0.096 0.038 552 511 303 66 1431 123
Jhenaidah 1119 0.023 0.104 65 10 0 0 75 991
Joypurhat 579 0.077 0.028 449 247 43 0 739 140
Khagrachari 387 0.002 0.003 4 3 0 0 7 8
Khulna 1461 0.056 0.076 414 214 49 19 696 952
Kishoreganj 1817 0.085 0.107 659 489 123 44 1315 1666
Kurigram 1306 0.048 0.079 446 71 23 0 540 883
Kushtia 1231 0.050 0.076 407 119 0 0 526 796
Lakshmipur 1090 0.090 0.119 343 251 77 165 835 1106
Lalmonirhat 796 0.017 0.031 113 0 0 0 113 209
Madaripur 732 0.119 0.154 246 223 212 61 742 961
Magura 582 0.083 0.104 204 157 20 30 410 515
Manikganj 878 0.093 0.116 363 275 30 30 698 870
Maulvibazar 1212 0.097 0.096 208 76 44 17 345 989
Meherpur 415 0.080 0.143 403 360 68 0 830 507
Munshiganj 905 0.066 0.073 85 221 120 85 511 561
Mymensingh 3212 0.047 0.074 1018 239 22 21 1301 2035
Naogaon 1641 0.024 0.043 322 10 0 0 332 597
Narail 455 0.092 0.111 116 136 97 10 360 432
Narayanganj 1845 0.047 0.055 160 269 306 0 735 870
Narsingdi 1403 0.052 0.066 236 217 87 85 626 788
Natore 1080 0.004 0.006 28 11 0 0 39 57
Nawabganj 1041 0.045 0.055 169 161 74 0 403 487
Netrokona 1406 0.115 0.136 570 585 188 43 1386 1636
Nilphamari 1159 0.029 0.053 288 0 0 0 288 530
Noakhalia1957 0.117 0.138 415 740 441 365 1962 2305
Pabna 1591 0.042 0.059 295 144 127 0 566 795
Panchagarh 625 0.017 0.032 93 0 0 0 93 170
(continues. . .)

843
Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
Policy & practice
Mitigation of arsenic in tube well water in Bangladesh
Sara V Flanagan et al.
Mitigation strategy
According to the model, Comilla is
the district with the highest number
of arsenic-related deaths – 3748 adult
deaths in 2009. is is because many
people there are exposed to high arse-
nic concentrations (Table 4). Resulting
losses in productivity could amount to
US$ 1.1 billion over the next 20 years
in Comilla alone.20 Supplying safe water
to the district’s population by install-
ing water points with no more than 50
people per water point, as well as small
communal piped water systems serving
a few hundred households, would cost
approximately US$ 44.2–49.2 million
depending on the choice of water supply
technology.20 is would be a fraction of
the economic losses that would result
from continued arsenic exposure, and
the health benets to generations not yet
born would be incalculable. Despite the
considerable capital costs involved, the
benets of an immediate investment in
an improved water supply system would
far outweigh the costs. Sustainability
and appropriateness for a given setting
should drive the choice of one arsenic
mitigation technology over another.20
e water sector in Bangladesh
urgently needs to nd a sustainable
way to supply safe water to people in
areas with high arsenic exposure and to
build capacity for local arsenic testing
for surveillance.28 Because of the dose–
response relationship that character-
izes arsenic-related health problems, the
public health benets of new safe water
supplies can be maximized by targeting
grossly contaminated areas (i.e. with
concentrations > 200 μg/L) rst. Such
areas are usually the ones having the
highest proportion of wells with water
that has arsenic concentrations > 50
μg/L. e Department of Public Health
Engineering (DPHE) of Bangladesh
and the United Nations Children’s Fund
(UNICEF) have succeeded in increasing
access to safe water in Comilla for a per
capita cost of only US$ 11 by following
this approach. Complete coverage of Co-
milla with safe water could be achieved
for an additional US$ 32 million. anks
to the provision of safe water points in
communities at risk as well as public
education and social mobilization, the
population drinking arsenic-safe water
in the intervention area in Comilla in-
creased steadily from 75% in 2007 to 81%
in 2009.29 However, in control areas ac-
cess to arsenic-safe water decreased from
93% in 2007 to 83% in 2009, perhaps
because of the continued installation of
new and inexpensive but contaminated
shallow tube wells and because adher-
ence to well switching has declined as
memories of arsenic awareness-raising
activities have begun to fade. e greatest
improvements in access were achieved
among the poorest population quintiles
in intervention areas, which points to
success in targeting people living in
poverty and extreme poverty.
As these examples suggest, past
achievements can be lost if arsenic miti-
gation eorts are not sustained. Markings
on wells from previous testing campaigns
have now worn o and the motivation
for promoting arsenic-safe water has
waned. e top-down blanket testing
approach of the past le no infrastructure
in place for monitoring existing wells or
for testing new wells.30 Building testing
capacity locally will lead to sustained
awareness in areas with high arsenic
exposure and give people more control
over their water supply, although instill-
ing a social norm of periodically testing
well water is essential for sustainability.
Implementing a local pay-for-use testing
system has already been found eec-
tive at motivating households to test
wells and, in turn, has strengthened the
commitment of the local population to
undertake arsenic mitigation measures.
By making it possible for people to know
which local wells are contaminated and
which ones are safe31 and by strategically
providing new water supply systems to
the populations most exposed to arsenic,
compliance with the national drinking
water arsenic standard can be facilitated.
Progress will not be even, however, since
some areas will prove more challenging
than others.32 Social acceptability and
sustainability are crucial factors to be
considered when choosing among arse-
nic mitigation strategies, in addition to
the costs of the technologies involved.20
For example, technologies for removing
arsenic from contaminated water would
cost an average of four times as much
over a span of 20 years as delivery of safe
water obtainable from other sources, and
would require high maintenance. us,
technologies that avoid arsenic contami-
District 2011 adult
population
(thousands)
PAF
(Sohel et al.)15
PAF
(Argos et al.)16
Annual no. of arsenic-attributable ED by arsenic concentration
(in μg/L) and in total (Sohel et al.)15
ED
(Argos et al.)16
10–49 50–149 150–299 ≥ 300 Total deaths
Patuakhali 966 0.023 0.042 188 0 0 0 188 346
Pirojpur 703 0.044 0.074 232 23 8 0 263 447
Rajbari 662 0.021 0.070 174 99 0 23 295 397
Rajshahi 1639 0.051 0.028 150 81 46 11 288 395
Rangamati 380 0.014 0.025 44 0 0 0 44 81
Rangpur 1826 0.023 0.040 333 30 0 0 364 625
Satkhira 1257 0.054 0.149 196 107 0 36 339 1604
Shariatpur 730 0.110 0.074 465 317 311 93 1186 459
Sherpur 850 0.055 0.063 718 184 18 0 920 455
Sirajganj 1957 0.039 0.085 219 37 24 0 281 1423
Sunamganja1556 0.151 0.146 659 1192 127 34 2012 1936
Sylhet 2168 0.054 0.057 370 513 90 25 999 1063
Tangail 2275 0.040 0.064 621 118 30 0 769 1236
Thakurgaon 879 0.003 0.006 26 0 0 0 26 48
Total 90 657 0.056 0.074 19 140 13 250 6504 3823 42 717 56 425
a One of five districts having the highest number of arsenic-attributable deaths per year (based on Sohel et al.’s hazard ratios).
(. . .continued)

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
844
Policy & practice
Mitigation of arsenic in tube well water in Bangladesh Sara V Flanagan et al.
nation, rather than remove arsenic, are
more cost-eective in the long term.33
Conclusion
In Bangladesh, ongoing exposure to
arsenic in drinking water calls for re-
newed and sustained mitigation eorts.
Exposure to arsenic could be eliminated
by 2030 if the government invested a
small fraction of its annual GDP growth
in providing an arsenic-safe water supply
and improving water quality monitoring
and surveillance activities. Reductions in
arsenic-related mortality would be noted
within about 40 years, as suggested by
observations in similarly exposed popu-
lations in Chile and, Taiwan (China),
where arsenic-related cancer mortality
started to decline gradually about 20
or 25 years aer measures to reduce
exposure were initiated and coronary
heart disease mortality declined even
faster.24,34–37 e current generation may
face the latent eects of lifetime exposure
to arsenic even aer switching to a safe
water source, but for future generations,
arsenic-attributable disease and death
would be a thing of the past. If, on the
other hand, population-wide chronic
arsenic exposure is allowed to continue
unchecked or to worsen as the popula-
tion grows and installs more private tube
wells, future generations will be saddled
with enormous health and productivity
costs. Appropriate interventions and ro-
bust investments, if undertaken now, can
prevent this from happening. ■
Acknowledgements
is paper reects the views of the
authors only and not those of UNICEF.
e authors thank Astrid van Agthoven,
Syed Adnan Ibna Hakim, Mi Hua, Deqa
Ibrahim Musa, Hans Spruijt and Siping
Wang of UNICEF Bangladesh, as well as
the Bangladesh Bureau of Statistics and
the Department of Public Health and
Engineering. is work was conducted
when all authors were aliated with the
Water, Environmental Sanitation Sec-
tion of UNICEF Bangladesh. Yan Zheng
is also currently aliated with Queens
College, City University of New York.
Funding: UKAid, UNICEF and the
Government of Bangladesh funded the
SHEWA-B project and the MICS Water
Quality Survey.
Competing interests: None declared.
Table 5. Population attributable fraction (PAF) of deaths and excess deaths (ED)
from arsenic exposure based on hazard ratios from two published sources,
Bangladesh
Arsenic
concentration
(µg/L)
Percentage
exposed
PAF
(Sohel et al.)15
PAF
(Argos et al.)16
ED
(Sohel et al.)15
ED
(Argos et al.)16
< 10 68.0 0 0 0 0
10.1–50 18.7 0.138 0.254 19 140 35 210
50.1–150 8.6 0.206 0.083 13 250 5302
150.1–300 3.0 0.265 0.405 6504 9945
> 300 1.8 0.259 0.405 3823 5969
Total 100.0 0.056 0.074 42 717 56 425
> 50 μg/L only 13.4 0.030 0.027 23 577 21 215

 
2009
 
4520
50   
10


50
50-10
1900024000

        
150
        
13 18 
   

51
200 
2
2006
112011

        

摘要
孟加拉国民用井水中的砷：控制砷暴露对健康和经济的影响和意义
使用2009 年孟加拉国全国饮用水水质调查的数据，对
孟加拉国慢性砷暴露状况作出最新评估。据发现，分别
有2000万和4500 万人口饮用水砷浓度超过50 μg/L的
国家标准和10 μg/L的世界卫生组织指导值。基于这些
最新砷暴露数据，结合当地人群由饮用水砷暴露导致的
死亡风险率的流行病学研究成果, 可估算到砷暴露浓度>

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253 845
Policy & practice
Mitigation of arsenic in tube well water in Bangladesh
Sara V Flanagan et al.
50μg/L和10〜50μg/L分别造成每年2.4 万以及可能多
达1.9 万的成人死亡。64 个省份的差异很大；在成年人
中，砷相关的死亡占所有死亡人数的0%至15%。由于每
18 个死亡的成年人中就有1 个与砷相关的死亡使生产力
下降, 这造成相当于未来20 年130 亿美元（US$）国民生
产总值的经济损失。降低砷暴露可两条路线并进：（一）
优先为饮用水砷浓度> 200 μg/L的约500 万暴露人口提
供安全的饮用水，及（二）建立地方砷检测能力。此方
法的有效性在联合国儿童基金 2006-2011 年孟加拉国
计划中得以示范，以人均11 美元的成本为砷危害地区安
全供水。在孟加拉国全国范围推广这样的方案将花费数
亿美元，但会提高国民的健康状况和避免国民生产力的
损失，造福子孙后代。
Résumé
Arsenic dans l’eau des puits tubulaires au Bangladesh: impacts sanitaires et économiques, et implications en vue de sa
réduction
Une enquête nationale sur la qualité de l’eau potable, menée en 2009,
a fourni des données qui ont été utilisées pour faire une estimation
actualisée de l’exposition chronique à l’arsenic au Bangladesh. On a
découvert qu’environ 20 et 45 millions de personnes étaient exposées
à des concentrations supérieures à la norme nationale de 50 µg/l et à
la valeur indicative de 10 µg/l de l’Organisation mondiale de la Santé,
respectivement. À partir des données d’exposition actualisées et des
ratios de risque de mortalité toutes causes confondues, sur la base
d’études épidémiologiques locales, on a estimé que l’exposition à
des concentrations d’arsenic supérieures à 50 µg/l et entre 10-50 µg/l
étaient à l’origine de 24 000, voire jusqu’à 19 000 décès annuels d’adultes
dans le pays, respectivement. L’exposition varie considérablement
dans les 64 districts. Chez les adultes, les décès associés à l’arsenic
représentaient 0% à 15% de tous les décès. Un taux de mortalité associé
à l’arsenic de 1 pour 18 décès d’adultes pourrait représenter au cours
des 20 prochaines années un fardeau économique de 13 milliards de
dollars américains (USD), en termes de perte de productivité seulement.
La diminution de la quantité d’arsenic doit suivre une approche à deux
niveaux: (i) considérer comme prioritaire la fourniture d’eau potable à
environ 5 millions de personnes exposées à plus de 200 µg/l d’arsenic, et
(ii) générer la capacité locale à effectuer des tests sur la teneur en arsenic.
L’efficacité d’une telle approche a été démontrée lors du programme
national 2006-2011 du Fonds des Nations unies pour l’enfance, qui a
fourni de l’eau potable à des zones contaminées par l’arsenic, pour un
coût de 11 USD par habitant. L’application à l’échelle nationale d’une
telle approche coûterait quelques centaines de millions de dollars, mais
permettrait d’améliorer la santé et la productivité de la population, en
particulier pour les générations futures.
Резюме
Мышьяк в колодезной воде в Бангладеш: влияние на здоровье и экономику и предпосылки
уменьшения вредного воздействия мышьяка
Для оценки длительного воздействия мышьяка в Бангладеш были
использованы данные национального исследования качества
питьевой воды, проведенный в 2009 г.. Около 20 и 45 миллионов
человек оказались подвержены воздействию концентраций
мышьяка, превышающих национальный стандарт, равный
50 мкг/л, и нормативное значение Всемирной организации
здравоохранения, равное 10 мкг/л, соответственно. Из
уточненных данных воздействия и соотношений риска общей
смертности, полученных из локальных эпидемиологических
исследований, было установлено, что воздействие мышьяка
в концентрациях > 50 мкг/л и 10–50 мкг/л является причиной
соответственно 24 000 и, возможно, не менее 19 000 смертей
среди взрослого населения в стране. Степень воздействия
колеблется в широких пределах в 64 районах: среди взрослого
населения число смертей, связанных с воздействием мышьяка,
составляет 0-15% от общего числа смертей. Уровень смертности
от мышьяка, составляющий 1 случай на каждые 18 смертей среди
взрослого населения, может стать причиной экономического
ущерба в размере 13 млрд. долл. США только в результате
снижения производительности труда в течении последующих
20 лет. Для уменьшения воздействия мышьяка следует
придерживаться двухъярусного подхода: (i) отдавая приоритет
снабжению безопасной водой примерно 5 млн. человек,
подверженных концентрации мышьяка > 200 мкг/л, и (ii) открывая
местные учреждения для лабораторных исследований мышьяка.
Эффективность подобного подхода была продемонстрирована
при осуществлении Государственной программы Детского фонда
ООН в 2006–2011 гг., в рамках которой зараженные мышьяком
районы обеспечивались чистой водой, и расходы на которую
составили 11 долл. США на душу населения. Расширение
подобного подхода в масштабе страны стоило бы несколько млн.
долл. США, но улучшило бы здоровье и производительность труда
населения, особенно будущих поколений.
Resumen
El arsénico en el agua procedente de pozos entubados en Bangladesh: El impacto sobre la salud y la economía y las
implicaciones en la mitigación de los efectos del arsénico
Una encuesta nacional sobre la calidad del agua potable llevada a
cabo en 2009 proporcionó los datos que se emplearon para realizar un
cálculo actualizado de la exposición crónica al arsénico en Bangladesh.
Se descubrió que aproximadamente 20 millones de personas están
expuestas a concentraciones superiores al nivel nacional de 50 µg/L y
unos 45 millones a concentraciones por encima del valor de referencia
de la Organización Mundial de la Salud de 10 µg/L. Partiendo de los datos
actualizados sobre la exposición y los cocientes de riesgo de mortalidad
por todas las causas basados en estudios epidemiológicos, se calculó
que la exposición al arsénico en concentraciones superiores a 50 µg/L
y entre 10–50 µg/L causan, respectivamente, 24 000 y hasta 19 000
muertes entre los adultos en el país. La exposición varía mucho en los
64 distritos. Entre las personas adultas, los fallecimientos relacionados
con el arsénico explican entre el 0 y el 15% de todas las muertes. La tasa

Bull World Health Organ 2012;90:839–846 | doi:10.2471/BLT.11.101253
846
Policy & practice
Mitigation of arsenic in tube well water in Bangladesh Sara V Flanagan et al.
de mortalidad por arsénico de 1 de cada 18 adultos podría representar
una carga económica de 13 mil millones de dólares estadounidenses
(US$) en productividad perdida en los próximos 20 años. La mitigación
de los efectos del arsénico debería seguir un enfoque de dos niveles:
(i) priorizar el suministro de agua salubre a aproximadamente 5 millones
de personas expuestas a niveles de arsénico superiores a 200 µg/L,
y (ii) construir centros locales con capacidad para realizar análisis de
arsénico. La eficacia de tal enfoque quedó demostrada durante el
programa por países 2006-2011 del Fondo de las Naciones Unidas
para la infancia, que suministró agua salubre a las áreas contaminadas
con arsénico con un coste de US$ 11 per cápita. La ampliación de
semejante enfoque a nivel nacional costaría algunos cientos millones
de dólares estadounidenses, pero mejoraría la salud y productividad de
la población, sobre todo de las generaciones futuras.
References
1. Ravenscroft P, Brammer H, Richards K. Arsenic pollution: a global synthesis.
Oxford: John-Wiley and Sons; 2009.
2. Smith AH, Lingas E, Rahman M. Contamination of drinking-water by
arsenic in Bangladesh: a public health emergency. Bull World Health Organ
2000;78:1093–103. PMID:11019458
3. Kinniburgh DG, Smedley PL, editors. Arsenic contamination of groundwater
in Bangladesh. Keyworth: British Geological Survey; 2001.
4. Multiple Indicator Cluster Survey (MICS) 2009. New York: United Nations
Children’s Fund, Bangladesh & Bangladesh Bureau of Statistics; 2010.
Available from: http://www.unicef.org/bangladesh/knowledgecentre_6292.
htm [accessed 21 August 2012]
5. Nickson R, McArthur J, Burgess W, Ahmed KM, Ravenscroft P, Rahman
M. Arsenic poisoning of Bangladesh groundwater. Nature 1998;395:338.
doi:10.1038/26387 PMID:9759723
6. Zheng Y, Stute M, van Geen A, Gavrieli I, Dhar R, Simpson HJ et al. Redox
control of arsenic mobilization in Bangladesh groundwater. Appl Geochem
2004;19:201–14. doi:10.1016/j.apgeochem.2003.09.007
7. Radloff KA, Zheng Y, Michael HA, Stute M, Bostick BC, Mihajlov I et al.
Arsenic migration to deep groundwater in Bangladesh influenced by
adsorption and water demand. Nat Geosci 2011;4:793–8. doi:10.1038/
ngeo1283 PMID:22308168
8. Towards an arsenic safe environment in Bangladesh: World Water Day, 22
March 2010. Dhaka: United Nations, Bangladesh and the Government of
Bangladesh; 2010. Available from http://www.unicef.org/bangladesh/
knowledgecentre_6131.htm [accessed 21 August 2012].
9. Johnston RB, Sarker M. Arsenic mitigation in Bangladesh: national screening
data and case studies in three upazilas. Journal of Environmental Science and
Health 2007;42:1889–96. PMID:17952790
10. Van Geen A. Promotion of well-switching to mitigate the current arsenic
crisis in Bangladesh. Bull World Health Organ 2002;80:732–7. PMID:12378292
11. Bangladesh national drinking water quality survey 2009. Dhaka: United Nations
Children’s Fund, Bangladesh; 2011. Available from: http://www.unicef.org/
bangladesh/knowledgecentre_6868.htm [accessed 21 August 2012].
12. Chen CJ, Kuo T, Wu M. Arsenic and cancers. Lancet 1988;331:414–5.
doi:10.1016/S0140-6736(88)91207-X PMID:2893213
13. Chen CJ, Chen C, Wu M, Kuo T. Cancer potential in liver, lung, bladder and
kidney due to ingested inorganic arsenic in drinking water. Br J Cancer
1992;66:888–92. doi:10.1038/bjc.1992.380 PMID:1419632
14. Smith AH, Goycolea M, Haque R, Biggs M. Marked increase in bladder
and lung cancer mortality in a region of northern Chile due to arsenic in
drinking water. Am J Epidemiol 1998;147:660–9. doi:10.1093/oxfordjournals.
aje.a009507 PMID:9554605
15. Sohel N, Persson L, Rahman M, Streatfield P, Yunus M, Ekstrom E-C et al.
Arsenic in drinking water and adult mortality: a population-based cohort
study in rural Bangladesh. Epidemiology 2009;20:824–30. doi:10.1097/
EDE.0b013e3181bb56ec PMID:19797964
16. Argos M, Kalra T, Rathouz P, Chen Y, Pierce B, Parvez F et al. Arsenic exposure
from drinking water and all-cause and chronic-disease mortalities in
Bangladesh (HEALS): a prospective cohort study. Lancet 2010;376:252–8.
doi:10.1016/S0140-6736(10)60481-3 PMID:20646756
17. Ahsan H, Chen Y, Parvez F, Zablotska L, Argos M, Hussain I et al. Arsenic
exposure from drinking water and risk of premalignant skin lesions in
Bangladesh: baseline results from the Health Effects of Arsenic Longitudinal
Study. Am J Epidemiol 2006;163:1138–48. doi:10.1093/aje/kwj154
PMID:16624965
18. Bangladesh Demographic and Health Survey 2007. Dhaka: National
Institution for Population Research and Training; 2009.
19. Mortality summary estimates for WHO Member States. In: Global burden of
disease estimates 2008. Geneva: World Health Organization; 2011.
20. Making economic sense for arsenic mitigation: a case study of Comilla district.
Dhaka: United Nations Children’s Fund, Bangladesh; 2011. Available from:
http://www.unicef.org/bangladesh/knowledgecentre_6872.htm [accessed
21 August 2012].
21. SEER cancer statistics review 1975–2006. Bethesda: National Cancer
Institute; 2006. Available from: http://seer.cancer.gov/csr/1975_2006/
results_merged/topic_year_lost.pdf [accessed 21 August 2012].
22. Smith AH, Steinmaus C. Health effects of arsenic and chromium in drinking
water: recent human findings. Annu Rev Public Health 2009;30:107–22.
doi:10.1146/annurev.publhealth.031308.100143 PMID:19012537
23. Dauphiné DC, Ferreccio C, Guntur S, Yuan Y, Hammond S, Balmes J et al.
Lung function in adults following in utero and childhood exposure to
arsenic in drinking water: preliminary findings. Int Arch Occup Environ Health
2011;84:591–600. doi:10.1007/s00420-010-0591-6 PMID:20972800
24. Yuan Y, Marshall G, Ferreccio C, Steinmaus C, Liaw J, Bates M et al. Kidney
cancer mortality: fifty-year latency patterns related to arsenic exposure.
Epidemiology 2010;21:103–8. doi:10.1097/EDE.0b013e3181c21e46
PMID:20010213
25. Smith AH, Marshall G, Yuan Y, Fereccio C, Liaw J, von Ehrenstein O et al.
Increased mortality from lung cancer and bronchiectasis in young adults
after exposure to arsenic in utero and in early childhood. Environ Health
Perspect 2006;114:1293–6. doi:10.1289/ehp.8832 PMID:16882542
26. Yuan Y, Marshall G, Ferreccio C, Steinmaus C, Selvin S. Acute myocardial
infarction mortality in comparison with lung and bladder cancer mortality
in arsenic-exposed region II of Chile from 1950 to 2000. Am J Epidemiol
2007;166:1381–91. doi:10.1093/aje/kwm238 PMID:17875584
27. Gardner R, Hamadani J, Grandér M, Tofail F, Nermell B, Palm B et al.
Persistent exposure to arsenic via drinking water in rural Bangladesh despite
major mitigation efforts. Am J Public Health 2011;101(Suppl 1):S333–8.
doi:10.2105/AJPH.2010.300025 PMID:21778503
28. George CM, Zheng Y, Graziano JH, Hossain Z, Rasul SB, Mey JL et al.
Evaluation of an arsenic test kit for rapid well screening in Bangladesh.
Environ Sci Technol 2012. Epub ahead of print 25 Sep 2012 doi:10.1021/
es300253p PMID:22866936
29. SHEWA-B health impact study midline report, November 2009. Dhaka:
International Centre for Diarrhoeal Disease Research, Bangladesh; 2009.
30. Zheng Y, Ravenscroft P, Rahman SM, Hakim SAI. Pay-for-use arsenic testing:
promoting demand-driven mitigation and monitoring in Bangladesh. In:
Proceedings of the International Conference on Arsenic in the Environment; July
22-27 2012; Cairns, Australia.
31. Madajewicz M, Pfaff A, van Geen A, Graziano J, Hussein I, Momotaj H
et al. Can information alone change behavior? Response to arsenic
contamination of groundwater in Bangladesh. J Dev Econ 2007;84:731–54.
doi:10.1016/j.jdeveco.2006.12.002
32. Chen Y, van Geen AF, Graziano JH, Pfaff A, Madajewicz M, Parvez F et al.
Reduction in urinary arsenic levels in response to arsenic mitigation
efforts in Araihazar, Bangladesh. Environ Health Perspect 2007;115:917–23.
doi:10.1289/ehp.9833 PMID:17589600
33. Johnston RB, Hanchett S, Khan MH. The socio-economics of arsenic
removal. Nat Geosci 2010;3:2–3. doi:10.1038/ngeo735
34. Yang C-Y, Chiu H-F, Wu T-N, Chuang H-Y, Ho S-C. Reduction in kidney
cancer mortality following installation of a tap water supply system in
an arsenic-endemic area of Taiwan. Arch Environ Health 2004;59:484–8.
doi:10.1080/00039890409603430 PMID:16381491
35. Chiu H-F, Ho S-C, Yang C-Y. Lung cancer mortality reduction after installation
of tap-water supply system in an arseniasis-endemic area in southwestern
Taiwan. Lung Cancer 2004;46:265–70. doi:10.1016/j.lungcan.2004.05.012
PMID:15541810
36. Marshall G, Ferreccio C, Yuan Y, Bates M, Steinmaus C, Selvin S et al. Fifty-
year study of lung and bladder cancer mortality in Chile related to arsenic
in drinking water. J Natl Cancer Inst 2007;99:920–8. doi:10.1093/jnci/djm004
PMID:17565158
37. Chang C-C, Ho S-C, Tsai S-S, Yang C-Y. Ischemic heart disease mortality
reduction in an arseniasis-endemic area in southwestern Taiwan after
a switch in the tap-water supply system. J Toxicol Environ Health A
2004;67:1353–61. doi:10.1080/15287390490471451 PMID:15371236