Shamya Dasgupta | September, 2002

Kolkata's waste recycling in its wetlands now poses dangers to public health. Vegetables that utilize Kolkata's sewage are increasingly laced with industrial toxins

	Toxic wastes in rivers re-emerge in the food chain

Certain components of sewage do provide valuable nutrients to soil, while others - heavy metals to be exact - find their way into the food chain and cause significant health concerns. Studies conducted down the years in the Eastern Indian metropolis of Kolkata (Calcutta) have produced alarming results. But to date, there appears to have been no progress in dealing with the problem, let alone finding a solution.

Statistics show that vegetables containing toxins grown in the Dhapa-Bantala area in Kolkata comprise about a fourth of the total amount of veggies sold in the Kolkata markets. Kolkata-based journalist Kunal Sengupta points to a particular area in a recent article he wrote: "A pilot study conducted by Central Pollution Control Board (CPCB) and the Calcutta University's Department of Agriculture revealed that the vegetables were contaminated with lead, cadmium and nickel. Scientists conducting the experiment had pointed out that these heavy metals if assimilated in the body in toxic amounts cause serious health hazards."

Distant solutions
Dr. Dhrubojyoti Ghosh is the Chief Environment Officer in the Ministry of Environment of the government of West Bengal. And over the years, he has been one of the main people offering solutions. Ghosh acknowledges that the problem still exists and has "reached an acute stage now". He also says, "The problem of sewage and waste matter reaching the agricultural fields is indeed a huge one. But though we have tried a number of steps, we are far from a stage where we can be positive about anything. It is a big problem for the environment of Kolkata and has resulted in alarming quantities of toxic material being mixed in the food we eat."

Ghosh is not wrong about the "alarming quantities of toxic material". Statistics reveal that the Dhapa-Bantala grown cauliflower contains about 44.1 mg of lead and 3.3 mg of cadmium in every kilogram of produce. Red leafy vegetables like saags (spinach) grown in the area contain 101.5 mg of lead per kilogram of produce. And, significantly, lead and cadmium poisoning can cause brain and kidney damage as well as nervous disorders.

When he had spoken to officials last, Ghosh had been told that the matter is being looked into. He says, "State environment department officials said that an action plan to preserve the wetlands was being given the final touches. They said that they were contemplating changes in the garbage dumping profile of the area, where organic and industrial wastes can be separated."

The east Kolkata wetlands are unique because they're a natural waste-recycling zone. But increasing industrialisation and automobile and factory emission have caused heavy metals like lead, cadmium and nickel to find their way into the soil. In the Kolkata wetlands system, where water flows into agricultural and fish ponds. The sewage water running from municipal pumping stations into the bheris (ponds) and sewage-fed fisheries, has decaying matter broken down by bacteria and sunlight to purify it of putrids. This, needless to say, is not enough considering the amounts of heavy metals.

Kolkata can't cope
The former director of the Geological Survey of India, Sunil Sen Sharma, says that the problem is two-fold and therefore, the solution also has to be directed in two different directions. He says, "One big problem, the basic one, is that the sewage - both liquid and solid - is used everywhere. It is used in the agricultural fields, in the water used for pisciculture, everywhere. The problem there is that the waste disposal system in the city of Kolkata is dead. The second problem, one that I personally think should be addressed with equal interest, is the utilisation of this waste."

Kolkata has a pathetic waste disposal system

Sharma continues, "The problem with the waste disposal system is that it is over 150 years old. The conduits and the canals that were constructed to carry the sewage outside the city are physically incapable of doing it anymore. The out-fall region for this sewage, which is outside the city, are all silted up as well. They need to be cleared. That's the only way the basic problem can be solved."

But it's the second problem dealing with wastes utilisation that poses a conundrum of sorts. Sharma says, "To move towards utilisation of this waste, it is necessary to preserve this waste and for that to happen, the authorities need to work out a two-pronged strategy and that is where the problem arises. Solid waste can easily be used in the power sector. Silting needs to be stopped and once that happens, the waste can be easily channelled wherever necessary. The liquid waste, on the other hand, can be recirculated. The wetlands, where the sewage usually ends up, can be tapped by processes of oxygenation."

In their study of the situation, the former secretary of the Irrigation and Water department of the government of West Bengal, SS Ganguly and executive engineer A. Dasgupta, provided some interesting arguments. The study, the last of its kind, was conducted in the mid 90's in Kolkata. The issue was the potential of the river Kultikong, where the out-fall channel of Kolkata had to be shifted, after the river Bidyadhari became incapable of handling the pressure. River Bidyadhari was the out-fall channel for just over 70 years and today, River Kultikong faces similar problems.

The entire responsibility, as Ganguly and Dasgupta write, cannot be handed over to the government or the other powers that be. The problem stems from the fact that the city, situated on the banks of the river Hooghly, has its natural slope away from the river. The problem is compounded, because the river Kultikong, a natural substitute for Bidyadhari, is 36 kilometres away from Kolkata. As a result, sewage and drainage water has to travel this distance in the carrier conduits and canals. Naturally, in the course of this journey, a substantial amount of suspended materials is deposited in the different reaches of the channel, thus blocking some of the drainage space.

The problem of solid and liquid sewage entering the wetlands and getting mixed with soil and water used in agriculture and pisciculture is not a new one. What is new is the information that alarming quantities of potentially lethal toxins form part of the Kolkata diet - or at least the part of it that comes from these blacklisted areas.

The other significant information is that in spite of being an old problem, no solutions have been discovered, despite years of supposed focus. The problem remains as it was. But with the population increasing with each passing day and industrialisation very much a part of everyday life, the situation is more acute than ever.

Shamya Dasgupta is a Delhi-based freelance journalist.

For more information, visit the following sites:
Kolkata: http://www.calcuttaweb.com/
Heavy Metals: http://www.osha.gov/SLTC/metalsheavy/
Central Pollution Control Board: http://envfor.nic.in/cpcb/
Geological Survey of India: http://www.gsi.gov.in/
Hooghly: http://www.cs.albany.edu/~amit/ganges.html