2004 WINNER

The newly discovered fern that could
stop a mass killer

By Amarendra Swarupl
Winner of the 20-28 category

Amarendra Swarup, 20-28 age group winner, finds that there is hope for the thousands of sufferers of arsenic poisoning or arsenicosis in Bangladesh

In a small cramped village clinic with peeling walls and languid fans, a doctor begins to examine a 14-year-old boy, the latest in a long line of patients. His palms and feet are covered with an intricate network of tiny gangrenous lesions, rivalling the finest mosaics Rome ever produced, and he is scared of dying. The doctor mutters soothing sounds, gives him some medicine for the pain and sends him away. There is little else she can do to halt his funeral march. The village has a thousand different names, the boy could be any one of the estimated 100,000 people suffering from arsenic poisoning or arsenicosis in Bangladesh, and the doctor is yet another helpless health official framed in the headlights of the biggest mass poisoning in history.

Over 29 million people live with the spectre of contracting arsenicosis from contaminated tube wells in Bangladesh alone, and many millions more across the Indian subcontinent are thought to be at risk. The tragedy is that this humanitarian disaster was inadvertently created by the very organisations that sought to help these impoverished individuals. In the 1970s, Unicef and the Bangladesh government instigated a mammoth exercise of digging tube wells across Bangladesh in an attempt to eradicate the surface waterborne diseases that afflicted much of the population. The programme was successful in drastically cutting the incidence of infectious diseases such as acute gastro intestinal disease and dysentery, particularly among children. However, it seems now, with the benefit of hindsight, that they may have been unwittingly writing their epitaph instead.

A pioneering study by Dipankar Chakraborti, an epidemiologist at Jadavpur University, Calcutta, India, spotlighted the first chronic arsenic poisoning cases in neighbouring West Bengal in the 1980s. By 1995, the Bangladesh government had concluded that the problem existed and was widespread. The ensuing furore, partly also fuelled by allegations of professional and bureaucratic negligence, has been accompanied by studies suggesting up to half of Bangladesh's estimated 10 million tube wells could be contaminated with arsenic at levels above the World Health Organisation (WHO) safety limit of 10 micrograms per litre. The culprit is generally held to be the leaching of natural arsenic sediment deposits into the ground water over millennia.

Arsenicosis is a painful, lingering killer. Prolonged exposure in drinking water can lead to skin lesions, gangrene, cancer and neurological changes. There is no cure and it is estimated that in Bangladesh 3,000 people die every year from arsenic-related cancer. According to Chakraborti, this may only be the beginning as the WHO estimates that, if left untreated, sustained exposure may lead to one in 10 people dying from arsenic-related diseases. More frightening, other studies have indicated that toxic amounts may also be accumulating in rice crops grown in these regions. Most methods of decontaminating tube wells are either prohibitively expensive or involve the generation of large volumes of toxic waste. In desperation, local health officials have taken to painting contaminated wells red and safe wells green in an effort to alert people, though at current rates, Unicef claims "it will take… 30 years to complete the testing".

Bleak though the situation is, there could be a scientific solution. New research by Mark Elless and his team at the Edenspace corporation in Dulles, Virginia, has shown that a recently discovered species of fern, Pteris vittata (brake fern), is capable of rapidly removing arsenic from drinking water and accumulating it in its shoots instead. Their repeated experiments with the brake fern showed that it is capable of reducing an initial arsenic water concentration of 200 micrograms/L by a hundredfold within 24 hours. Further, for concentrations up to 500 micrograms/L, there is a rapid reduction within 18 hours, and complete removal of arsenic within 48 hours. Most importantly, their experiments show that the ferns can be used repeatedly to remove arsenic from water continuously.

The method, known as phytofiltration, has far-reaching implications in places such as Bangladesh, as it provides a potentially cheap method for decontamination. Elless points out that the fern species are perennial, and much of the stored arsenic can be removed through extracting the plant sap. Thus, they can be used repeatedly, and offer a significantly cheaper and environmentally friendly alternative to other proposed methods, such as chemical treatment systems and bioremediation. Further, the plants are ideally suited to warm humid climates and can be grown directly in water.

As with any new research, however, there are also those who have their doubts. Some, such as Chakraborti, are sceptical of approaches that seek to decontaminate tube wells and favour instead a return to exploiting the large surface waters of Bangladesh. Others point to the difficulties of dealing with the vast daily volumes of water used and the lack of infrastructure. Elless himself admits that extending their discoveries to treating the Bangladesh epidemic is a long-term goal.

Nevertheless, whatever caveats may be raised, there is hope at least now that the epitaph may yet be rewritten.