ABDUL KASEN lifted a green leaf “bandage” to reveal a large growth on the
palm of his hand. The chances are that his cancer came from 20 years of drinking
water from a village well laced with arsenic. Five of his six children also have
skin blemishes and melanomas associated with the poison.
His well, in the village of Barai Kandi near Dhaka, the capital of
Bangladesh, is one of an estimated 2 million out of a total of 4 million in the
country that contain dangerous amounts of arsenic. On my Saturday morning visit
to the village with Akhtar Ahmad of the Bangladeshi government’s National
Institute of Preventive and Social Medicine in Dhaka—the first by anyone
equipped to test the water—we found that all the water supplies were
contaminated.
The villagers asked us for advice. We found the well containing the least
contaminated water and suggested they all drink from that. But what if they
wanted safer water? Should they dig deeper or shallower, farther from the
village or closer? We didn’t know the answer. British scientists at a conference
in Dhaka told us that they might have answers in three months. But our visit was
two years ago this week. And the answers have yet to arrive.
Advertisement
At the centre of the dilemma over what advice to give the local people lies
an extraordinary row between British geologists. One side claims that the other
is threatening to undermine efforts to help millions of Bangladeshis who, for
the past 20 years, have been unknowingly drinking underground water laced with
arsenic washed down from the Himalayas.
The debate matters because new boreholes are still being sunk almost daily in
Bangladesh. Where they are sunk and to what depth is crucial to the health of
the locals who will rely heavily on the water supplied for drinking as well as
irrigation.
John McArthur of University College London, whose team was the first to
report on the geochemistry behind the world’s largest outbreak of arsenic
poisoning, is accusing researchers at the British Geological Survey (BGS) of
withholding vital figures. The BGS carried out the first comprehensive chemical
testing of borehole water in Bangladesh almost two years ago. It has already
concluded that water drunk by up to 40 million Bangladeshis contains arsenic at
sometimes hundreds of times the recommended safety level of 10 micrograms per
litre. But McArthur says that the BGS has refused to allow him access to most of
the measurements made on over 2000 water samples taken during the survey.
McArthur says the embargo is preventing scientists in Bangladesh and
elsewhere from reaching agreement on how the arsenic got into the water. “The
BGS holds the only comprehensive data set capable of proving which [theory] is
right,” he says. The answer dictates where safer wells can be dug in the absence
of practical chemical treatments for the poisoned wells.
The BGS’s David Kinniburgh, one of the project leaders, denies the charge. He
insists figures will be available later this year and that they contain no big
surprises. “If I had thought any of the data would change the world I would have
put it out,” he says.
The roots of the arsenic crisis go back a generation to when most
Bangladeshis drank water from rivers and ponds that were often contaminated by
sewage. Thousands died each year from gastrointestinal diseases. International
agencies such as UNICEF devised a plan to sink boreholes into the sands of the
Ganges river delta that covers much of Bangladesh and the neighbouring Indian
state of West Bengal. Today, there are more than 4 million such boreholes
supplying water to 95 per cent of Bangladesh’s villagers.
Unfortunately, nobody thought to check the underground water for natural
poisons until symptoms began to emerge, first in West Bengal (New
Scientist, 16 September 1995, p 14) and later in Bangladesh. It is now
clear that for over a decade villagers have been drinking water containing more
than 1 milligram of arsenic per litre, 100 times the international safety
limit.
Whole villages now show symptoms ranging from skin blemishes to lung
diseases, skin cancers and liver failure. Doctors predict that unless urgent
action is taken, there will be an epidemic of arsenic-related deaths across
southern Bangladesh. Allan Smith, an epidemiologist from the University of
California at Berkeley, has warned the WHO that within a few years, one in ten
deaths in the region could be due to arsenic poisoning.
Late last year, the Bangladeshi government began screening the country’s
boreholes. But finding the estimated 2 million affected wells is a major task
because contamination levels vary drastically—even between neighbouring
boreholes. Cheap, easy-to-use testing kits that would allow villagers to locate
safe water are not yet available.
But how does arsenic enter water from the sands? Dipankar Chakraborti, head
of the School of Environmental Studies at Jadavpur University in Calcutta, who
first exposed the disaster, argued that village pumps have lowered water levels
and allowed oxygen to attack the arsenic-bearing iron pyrite deposits in the
sediment. The resulting oxidation has released the arsenic into the water. His
theory was accepted at the first international scientific conference on the
disaster, held in Dhaka two years ago. He said again this month: “There may be
many mechanisms involved, but oxidation of pyrite is undoubtedly one of
ٳ.”
But both McArthur and Kinniburgh have independently concluded that his theory
is probably wrong. The essential process, they say, is not oxidation but
reduction. Much of the arsenic is bound to iron oxyhydroxide compounds in the
top 40 metres of the delta sediments. Away from the surface, rotting vegetation
has consumed all the oxygen dissolved in water, creating an environment in which
these compounds release iron and arsenic. But although McArthur agrees with
Kinniburgh that reduction is the most likely explanation, he fears that without
more complete figures it will not be possible to convince local scientists such
as Chakraborti of this.
“With many people in Bangladesh and India still convinced of the oxidation
argument, it is a tragedy not to have published the data,” McArthur says.
“Pyrite oxidation would happen mainly in shallow wells [less than 10 metres
deep], and the answer will be to dig deeper wells. But iron reduction would
happen at deeper levels and the answer will be shallow wells.”
But Kinniburgh remains firm about not publishing the information early. “We
didn’t put all the data in the first report because in some cases we were not
sure of it, and in other cases it was not important. Also we wanted to have the
first chance to look at our data properly.” He says his final report will be
complete in April and published later this year.
Kinniburgh collected his samples in early 1998 and in June of the following
year he published some of the figures, with his preliminary conclusion that
reduction was to blame. But McArthur had already scooped him in Nature
in September 1998, using a much smaller amount of data from his own study of 46
wells in central Bangladesh to reach the same conclusion.
There is no love lost between the two. Last October, Kinniburgh told New
Scientist that McArthur had been guilty of “rushing into print” and of
“drawing a general conclusion from insufficient data”.
There is another potential culprit complicating the story: agricultural
fertilisers. Kinniburgh says that his figures do show “unusually high phosphate
concentrations” in the region’s water, but he does not believe fertiliser is to
blame. McArthur argues that without the unpublished research the issue remains
up in the air.
McArthur has spent the past six months writing letters to officials in the
BGS, the British government’s Department for International Development (DFID),
which funded the research, and the government of Bangladesh demanding release of
the data. He asked Clare Short, the overseas development secretary, if the DFID
will “explain why confidentiality is an interest placed above that of the
welfare of the people of Bangladesh and West Bengal”. He told New
Scientist, “If this were the US, I would have had this data by now through
the Freedom of Information Act.” For McArthur, the failure of foreign water
experts to spot the arsenic problem 20 years ago is reason enough for complete
openness now.