Natural remedy: Prof. Madhusnata De and her students at the lab

Each time she visits Atghara, a village in southern West Bengal, geneticist Madhusnata De advises children, men and women between 10 and 25 years of age to consume three cups of black tea each day. It?s a prescription that De hopes will help the people there fight the damage that chronic arsenic poisoning has wreaked in their bodies. Atghara is among hundreds of villages across eastern India where groundwater used for drinking is laced with high levels of arsenic.

Now Atghara is also where scientists are pitting black tea against arsenic. De, a geneticist at the Vivekananda Institute of Medical Sciences (VIMS), Calcutta, and her colleagues have been trying to hunt down natural remedies to counter the ravages of chronic arsenic poisoning. The effort to coax people to consume black tea follows nearly five years of laboratory research as well as a series of animal experiments to determine the effect that black tea might have on exposure to arsenic.

?We picked tea because it is a common drink, and less expensive than other agents that may offer similar benefits,? said Dr Geeta Talukder, a senior consultant at VIMS. Some scientists have cautioned that there is no evidence yet to suggest that black tea will prevent arsenic damage in humans, but VIMS researchers say the tea-versus-arsenic strategy is worth pursuing. They plan to study the effect of black tea consumption on chromosomal damage in people who live in the arsenic-affected village.

The department of biotechnology supported the first studies at VIMS on the search for natural remedies to tackle chronic arsenic poisoning, but the National Tea Research Foundation is now funding the project.

?We?re not trying to help the tea industry,? said Talukder. ?Whatever the results ? positive or negative ? we?ll publish them.? The VIMS researchers say the results of the impact of tea on chromosomal damage are expected only at the end of 2005.

Environmental scientists have cautioned that India?s arsenic problem may be more widespread than thought earlier. While West Bengal is the worst affected zone, a study by Dipankar Chakraborti at the Jadavpur University last year raised the spectre that other parts of middle Ganges plain in eastern India may also be affected. Chakraborti analysed water from 205 tubewells in Bihar and found that more than 100 had arsenic levels five times the maximum allowed limit.

A mid-1990s analysis by Chakraborti had said that over one million people across hundreds of villages in West Bengal were consuming water with dangerous levels of arsenic. Prolonged arsenic ingestion causes skin lesions, liver and spleen damage, as well as skin cancer. Researchers also believe that bladder, genitourinary, and lung cancers in residents of these villages may be attributed to arsenic.

Although arsenic is recognised as a human carcinogen, how it causes cancer was unclear for a long time. Then, in the late 1990s, Tom Wei, a researcher at Columbia University?s School of Public Health, showed that arsenic causes chromosomal damage.

Three years ago, Wei and his colleagues showed that this genetic damage was driven by free radicals, or reactive oxygen species, a class of molecules known to be highly toxic to biological material.

The researchers observed a dose-dependent generation of reactive oxygen species in mammalian cells exposed to arsenic ? the higher the exposure, the greater the generation of free radicals. Arsenic induces within five minutes a three-fold increase in the production of free radicals by the cells exposed to arsenic, Wei had reported in the Proceedings of the National Academy of Sciences. Two years ago, the researchers also showed that the induction of free radicals was significantly reduced in the presence of antioxidant enzymes.

At the VIMS, Talukder and her colleagues began to look for natural substances with antioxidants that could combat free radical damage. In one study, they showed that genetic damage to cells by arsenic could be prevented by garlic extracts. A preliminary study five years ago indicated that black tea also had a protective effect against arsenic. ?Tea contains substances called polyphenols which are known to act against free radicals,? said VIMS geneticist De.

The researchers followed that up with a series of studies on mice to determine how black tea affects chromosomal damage. In the latest study published last month in the Indian Journal of Experimental Biology, Sandeep Poddar, DBT project scientist at the VIMS, has authenticated previous findings that tea significantly decreased the chromosomal damage caused by arsenic.

Through experiments on laboratory mice, Poddar found that administration of black tea infusion daily for six days, simulating human consumption, reduced the effects of a moderate concentration of sodium arsenite. The study also found that the addition of iron as a dietary supplement to the mice did not alter the protective action of tea. But giving both tea and iron did not increase the protective action of tea.

However, scientists caution that more studies are needed before black tea can be recommended as a protective agent against chronic arsenic poisoning.

Although animal studies use the same concentration of tea taken by humans, the total tea consumption by the animals in relation to body weight in such experiments is much higher the daily human consumption.