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Volume 16, Number 2 |
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"Civil and Environmental Engineering at
MIT" |
Search for cleaner water causes major problems with arsenic in Bangladesh public water supply
To save children from dying of diseases spread through polluted surface
water, the government of Bangladesh and international development agencies dug
hundreds of thousands of tube wells around the country starting in the 1970s.
The wells were convenient and the water retrieved from 30 to 100 ft down
didn’t have to be boiled to kill germs, thereby improving health and saving
money in a desperately poor country. As the incidence of chronic waterborne
diseases plummeted, the new water system appeared to be a triumph of public
health,
Created with the best of intentions, this clean water program has led to
“one of the worst environmental disasters in the history of mankind,” says
Borhan Badruzzaman, a visiting scientist from the Bangladesh Univ. of
Engineering and Technology who has worked with Prof. Charles Harvey at the
Parsons Lab. Because of the regional geology, this biologically uncontaminated
water is laced with naturally occurring arsenic in concentrations up to 40 times
over the declared safe level.
Arsenic as a public health problem was first identified in West Bengal,
India, where the geological formations, economic conditions, food habits, and
tube wells are similar to those in Bangladesh. In the early 1990s, people
started to develop arsenicosis, starting with skin rashes and leading to
sometimes fatal problems with the lungs, kidneys, and bladder. Symptoms varied
widely, depending on the arsenic level in the water, the victim’s nutritional
condition (malnourished people are more vulnerable), and individual reaction.
Badruzzaman says, “Some people show skin blisters in six months of drinking
the water, while other people can go for years before symptoms appear.”
Facing a flood of cases in West Bengal, health workers started looking
for similar problems in Bangladesh. “What we found was staggering. Currently,
about 1/3 of the tube wells in Bangladesh pump up water exceeding the arsenic
standard of 50 ppb (parts per billion). In some areas arsenic levels are 2000 ppb, 40 times over the acceptable level for drinking.
Most of the wells register 200 to 400 ppb of arsenic. Drinking that water for a
long time is bound to hurt your body,” notes Badruzzaman. “About 55 million
people are exposed to arsenic poisoning. It’s unimaginable to combat such an
enormous disaster.”
As villagers unknowingly accumulated the toxic heavy metal, eventually
“hundreds of thousands of patients came pouring in clinics with varying
degrees of arsenic-related problems, from skin rashes to the loss of fingers,”
recounts Badruzzaman. Because doctors weren’t expecting to see arsenic
poisoning, they often attributed the skin problems to an inexplicable outbreak
of leprosy.
Researchers at universities around the world are studying different
aspects of the problems, from the geology and hydrology to remediation and
treatment of arsenic poisoning. MIT, led by Prof. Charles Harvey of Parsons Lab,
Columbia Univ., and the US Geological Service are focusing on where the arsenic
originates, how it is released from sediments, and how it moves through the
groundwater. Badruzzaman, Asharf Ali, and Feroze Ahmed run the collaboration with Bangladesh Univ. of Science and
Technology (BUET), and Prof. Shafiqul Islam ‘91 (PhD) is collaborating on the
project from Univ. of Cincinnati.
Fifteen monitoring wells have been established by BUET in Sreenagar, close to the Ganges River, with water and sediment samples
collected and analyzed in Bangladesh, Europe, and North America. Badruzzaman is
"really excited about this work. Our experiments are designed to determine
the chemistry of arsenic release and mobility, with the aim of developing a
model to see how the arsenic is released. As the groundwater is recharged every
monsoon, we’ll learn why the arsenic is moving and how the irrigation wells
are affecting it.”
In recent years Bangladesh has become self-sufficient in grain
production, thanks to widespread irrigation wells and high-yield strains of
rice. Since thousands of wells supply arsenic-laden water to the rice fields,
people are wondering if arsenic is infiltrating the food chain through their
most basic staple food. In addition, all the pumping during the irrigation
season “actually changes the movement of the water and arsenic from one depth
to another,” says Badruzzaman. “Ongoing studies are trying to determine how
much of a role irrigation plays in the mobility of arsenic.”
From their lab and field work, the BUET researchers learned that the
arsenic concentration increases with depth in the aquifer and peaks around 100
to 125 ft down before starting to decrease. Around 400 ft down, a thick layer of
clay prevents water from moving between the aquifers. Underneath the clay lies a
confined supply of arsenic-free water. However, pumping water from that depth
requires substantial power. Many villages have no electricity, and diesel pumps
cost money to install and run.
Given past experience, says Badruzzaman, an additional worry is that
“maybe the deep wells will also become tainted, and after 10 years we’ll
realize that we made the wrong decision to tap them. We have to know more about
the movement of arsenic in groundwater before deciding whether deep wells are
the answer. Now at least we have data to anticipate what’s going on. If we
know how arsenic is released from soil, we can develop computer models that will
predict that given certain environmental conditions, arsenic will or will not
move from Point A to Point B in a certain time. This knowledge will help us plan
where to dig wells, or decide if they can be installed at all.” In any case,
he says. “My perspective is that one cannot provide any unique solution that
will be applicable to the whole country.”
Badruzzaman criticizes a World Bank-funded project run by the government
of Bangladesh to identify and shut down the tainted wells. “They test the
well, paint it red if it’s pumping up water full of arsenic, and tell people
they cannot drink from that well. What’s the alternative? People can’t live
without water! We need simple, cheap remediation techniques.” With the average
income in Bangladesh hovering around $380/year, “you cannot expect someone to
spend $35 to $40 on a unit which also has a sizeable running cost.”
BUET and the United Nations Univ. of Japan have collaborated on various
options for arsenic removal using filtration kits that can be installed at home.
The basic principle is to pour water from the tube well through another
container containing a filter, which draws out the arsenic. The units must be
efficient, easy to maintain and operate, and affordable by an extremely poor
population. These filters are being tested in villages now, and the water
quality monitored by BUET students.
To gain first-hand knowledge of the situation, CEE postdoc Chris Swartz
and students Nicole Keon and Winston Yu traveled to Bangladesh in 2000 with
Charles Harvey. Last year Yu, fellow student Khandaker Ashfaque, and postdoc
Volker Niedan returned to gather further information, and the former two are
carrying out additional fieldwork this year. Harvey and Shafiqul Islam organized
and chaired an NSF-sponsored meeting in Bangladesh in January 2002 to examine
the water resources, geology and geomorphology, ecology, agriculture and
environmental planning issues of the Ganges-Brahmaputra Delta.
Badruzzaman mentions that the country definitely needs international help
to handle the arsenic problem, “because it’s a disaster of a proportion that
nobody can even imagine.” Current figures estimate that 200,000 people already
suffer from the distinctive skin lesions caused by arsenic, and an estimated
7,000 people have died of arsenic-related cancers of the bladder and kidney.
“I hope this project will be successful and gives us the knowledge of
how arsenic moves from one place to another, and whether we can anticipate the
movement and release. That way we’ll be able to plan future action for how to
remove arsenic from the water supply, whether it means using deep wells or
alternate resources.” While research is a slow and deliberate process, “in
the meantime we have to address the effect of arsenic immediately. This whole
problem has two aspects: to provide clean water to the affected people, and to
try to treat those who already show symptoms of arsenic poisoning.”
For more information about this complex problem, Badruzzaman recommends
checking two excellent websites: •
the Bangladesh Arsenic Mitigation and Water Supply Program at http://www.bamwsp.org •
West Bengal India and Bangladesh Arsenic Crisis Centre at http://bicn.com/acic/ |
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