Publication: Sunday Sun
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Paper Date: Sun, Jan 24, 2002
Byline: Terry Ally
Last week the Barbados Water Authority (BWA) made
a significant announcement which raised no eyebrows and ruffled no feathers,
indicating that its public relations was so good that no one understood the
gravity of the situation. It announced that the island’s largest water
catchment – The Belle – had a high level of nitrate-nitrogen in the water.
In the same breath, it also said, according to one Press report, that there was
“no evidence that there has ever been either bacteriological or chemical
contamination” of the island’s water supply – another very profound
statement.
What’s the big issue?
One recent study in Iowa, United States, showed that nitrate can cause bladder
cancer and another in Britain showed that nitrate can cause gullet cancer.
Nitrate comes from human sewage, livestock manure, fertilisers, cemeteries and
landfills, and the BWA failed to explain – or reporters failed to report –
how bacteriological or chemical contamination of drinking water could be so
categorically ruled out. The level found in 2000 was 9.4 milligrammes per litre
(also expressed as part per million or ppm) which was just under the World
Health Organisation’s standard of 10 ppm for drinking water.
The BWA did not reveal the 2001 level.
In 1996, the Weekend Nation reported islandwide nitrate-nitrogen levels at
between 6.0 and 8.0 ppm. Now in 2000 it is 9.4 ppm, but it does not mean that it
is a straightforward upward curve. It is a little more complicated because there
are a number of variables to consider. Take the Barbados Water Loss Study done
in the mid-1990s, for example. It showed very high levels during the El Niño
droughts of 1994, yet when El Niño faded and the rains came, the levels
plummeted.
“It simply means dilution and dispersal,” an environmental chemist
explained.
The levels have to be closely examined within environment contexts to determine
a trend from a spike.
The news report of February 16, 1996, quoted Bob Dawson of Stanley Association
(the same company doing The Belle Study) as saying that one theory was that the
bulk of the nitrate pollution was coming from populations in the rural areas,
upstream of underground water courses. If the theory was correct, he said, there
may be a need to provide water treatment in those areas or at the wellhead which
could cost about $50 million. He also said it pointed to the need for the use of
more efficient fertilisers to reduce nitrate seepage into the ground.
Bacterial contamination in drinking water wells was non-existent because the
water was being chlorinated and that gives no indication as to whether bacteria
from waste water was reaching the aquifer. Unchlorinated water in agricultural
wells gives a clue – the contamination level was astronomical.
So what is the solution? Why another pollution study to add to the volumes that
were done since squatting was officially sanctioned in The Belle? If all the
potential sources are known, why not just sewer The Belle?
It’s not that easy, said a BWA official. First, they have to know how much is
coming from human and agricultural activities before knowing how to stem the
flow. If the authority goes ahead and sewers, it could lead to increased
construction and human activity and that could lead to nitrates being replaced
by another contaminant; that is why it is so important to determine all the
possible environmental impacts. The final decision could just be to build a new
water treatment plant.
Nitrogen is the nutrient found in agricultural applications like fertilisers. It
also naturally occurs in organic forms from decaying plants, animals, and in
human waste and waste water. Bacteria located in the soil and pore spaces of the
coral rock convert it to nitrate. Nitrate is the primary source of nitrogen
which is required by plants for their survival. Nitrate contamination occurs
when there is more nitrate in the soil than plants can use. It is very soluble
and easily dissolved in water and extremely difficult to remove. Only three
processes can remove it: (1) demineralisation by distillation or reverse osmosis
(which the Spring Garden Desalination Plant uses); (2) ion exchange which has
shortcomings and additional environmental problems, and (3) blending through
dilution.
Home filters, water softeners and boiling will not work. In fact, boiling is the
worst thing to do because it increases the concentration of nitrates in the
water.
Methemoglobinemia or “blue baby syndrome” is the well-known health risk. In
the first few months of life, there are certain types of bacteria which live in
the digestive system of babies. These bacteria change nitrate into toxic nitrite
which reacts with haemoglobin (which carries oxygen to all parts of the body) to
form methemoglobin, which does not carry oxygen. As a result, a baby fed on
water containing high levels of nitrate-nitrogen gradually suffocates. As the
baby gets older, around three months, the digestive system develops and stomach
acid kills most of the bacteria that convert nitrate to toxic nitrite.
New studies now show that nitrate can cause cancer in adults. In an article
published in the May 2001 edition of the journal Epidemiology, University of
Iowa researchers reported on a study done on 22 000 Iowa women for bladder
cancer as a result of nitrate-nitrogen in drinking water.
They found that 20 per cent of ingested nitrate is transformed in the body to
nitrite, which can then undergo transformation in the stomach, colon and bladder
to form N-nitroso compounds which are known to cause cancer in a variety of
organs in more than 40 animals species, including higher primates.
“The United States Environmental Protection Agency drinking water standard is
10 ppm nitrate-nitrogen. Our study suggests that nitrate levels much less than
that could be a serious health concern,” Peter Weyer, association director of
the University of Iowa Centre for Health Effects of Environmental Contamination,
said in an article published by the Environmental News Service.
Researchers found that women whose average drinking water nitrate exposure level
was greater than 2.46 ppm were 2.83 times more likely to develop bladder cancer
than women in the lowest nitrate exposure level of less than 0.36 ppm.
Last week, researchers at Glasgow University in Scotland linked increased use of
nitrate fertilisers to an alarming increase in gullet cancer in Britain. The
cancer rate increased by 300 per cent in the last 20 years, prompting
investigative studies. The researchers led by Professor Kenneth McColl
discovered a link between nitrates in fruit and vegetables and gullet cancer.
“We are still carrying out this study and are certainly not saying people
should stop eating vegetables,” he was quoted by the Guardian newspaper. “It
appears that the mass production of vegetable in the Western world since the
last world war may be the underlying factor that has led to such huge increases
in this form of cancer.”
He said organic produce would not be any healthier because nitrates also come
from natural fertilisers like manure.
So should we limit the amount of tap water we drink and vegetables we eat in
Barbados? It’s a difficult question without hard data. When standards are set,
the social context of a country has to be factored in.
Nitrate comes from many sources and can be ingested through drinking water or
foods such as fruit and vegetables. If it is determined that a human body can
tolerate a maximum level of, say, 10 ppm, then it first has to be ascertained
just how much is coming from each source based on the average Barbadian diet.
If, for example, Barbadians ingest 4 ppm through foods, then the maximum level
in water should be 6 ppm and standards set accordingly. However, Barbados does
not do such research and borrows heavily from the Environmental Protection
Agency, the European Union, or Codex Alimentarius which set limits based on
dietary data from larger countries.
At this time, the only real solution is for Government to act swiftly and
decisively to either remove the source of nitrate-nitrogen in The Belle water,
or construct another reverse osmosis plant to treat the water.
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