Murunga and water purification


Two writers, Dr. Pethiyagoda (9-01-2016, Island) and Dr. Weeraratne (11-01-2016 Island) have raised the question why Sri Lankan scientists and government authorities are not moving to Murunga seed (seeds of Moringa Oleifera, or "drumsticks") to exploit its claimed efficiency for water purification- a "green solution". The two writers argue that Murunga seeds can remove alleged toxins from the water in the North Central province (NCP) and alleviate a serious chronic kidney disease (CKD) found in the region. Dr. Weeraratne also refers to an international expert consultation (IEC) held in April 2016 regarding CKD, and says that 27 recommendations were made, and raises ire as to why they were not implemented.

However, the IEC made no mention of using Murunga seed for water purification in any of their recommendations. Since "Murunga seed" has been proposed every season by some writer, let us "think through" the use of Murunga to purify domestic water for the NCP. A family of five would need about 50 liters of water a day, allotting about three liters per person purely for drinking, while a common 35 liters is left for cooking and other needs where the water is ingested/used in other forms. Usually one Murunga kernal is needed for the purification of one liter of water. Hence the family needs 50 kernals of Murunga per day. Seeds have to be prepared everyday for water purification as they go bad once removed from the drumstick. A drumstick may contain a dozen seeds of which several may be bad or discoloured. If we assume about 8 to 10 useful mature seeds per Mururnga drumstick, we need 6-8 drum sticks per day.

Their current market cost is minimally Rs. 25 per day. Of course, if even a tenth of the one million people in the affected area begin to buy Murunga everyday the price will shoot sky high!

But this is not all; the mature Murunga has to be processed before using for cleaning water. There is no ready-made product available in the Lankan market. The seeds have to be removed from the pods, shelled to get clean kernels, crushed in a grinder or "wangediya" and sieved to a fine powder (try this and see what a messy process it is!).

A paste of the powder made with water is shaken vigorously to "activate" it. This paste is added to the 50 liters of water from the well (or other source), stirred thoroughly and allowed to sit for a few hours. During this time turbidity and toxins get absorbed into the murunga-powder in suspension. The water is filtered and used for cooking, drinking etc. One member of the family has to devote (at least) an hour for this daily ritual. At Rs. 800 a day (8-hour work day) typical of NCP labour, this adds Rs 100 to the cost of the 50 liters of water. If done by a junior we may cost it at Rs 50. Hence the total cost is now Rs 75 for 50 liters, i.e., at least Rs 1.50 per liter of water.

Furthermore, what does the farmer do with the filtered sludge which now contains all the pollutants possibly causing kidney disease? He cannot put back the sludge into the soil to re-pollute the soil at a much higher concentration! The farmer may cut his costs by growing Murunga in his back yard. This will imply some labour, and a two-year wait before mature produce Murunga. But unfortunately, another danger looms over him – the threat of bio-accumulation of toxins in the Murunga plant.

The rice plant, when planted in most soils even with less than 5 parts per billion of cadmium is known to concentrate such toxins in its seeds, leaves etc, as shown by the chemical analysis of Sri Lankan rice by Prof. Meharg of Scotland, and confirmed by recent detailed work by the team of Prof. Chandrajith at the geology department, Peradeniya University. This however does not mean that the Sri Lankan rice poses a health risk, because the plant has absorbed not only toxins like cadmium, but large amounts of mitigating substances like zinc and selenium, making it safe for consumption. In fact, the work of Meharg, and Chandrajith and collaborators show that the rice from the WET ZONE contains significantly more cadmium than dry-zone rice! But the wet-zone rice is also compensated by mitigating substances and may be regarded as posing no health risk. It should be noted that oysters and many kinds of fish sold in Europe have more cadmium than Sri Lankan rice, but they are legally marketed because there too, mitigating substances like zinc are present and suppress the effect of cadmium.

Not only rice, many other grasses, plants and trees "bio-accumulate" toxic metals from the soil during its growth. The chemical analyses of the NCP soil and water by independent scientific organizations have shown the absence of significant amounts of metal toxins or residues of pesticides like glyphosate in the NCP. But glyphosate has been banned on the assumption that it is there, and causing chronic diseases! The problem lies in the capacity of plants like rice or murunga to bio-accumulate even from trace concentrations. The WHO-NSF study revealed that lotus root and kohila (Lasia spinosa) were rich in accumulated metal toxins, and recommended their avoidance. The murunga tree's leaves, pods etc., are likely to be rich in toxins. Does murunga have accumulations of mitigating ions in sufficient amounts? While this is likely, no analysis is available, unlike in the case of rice.

Most of the murunga available in Indian groceries in Canada come from South India, and I hesitate to consume the product.

If the murunga kernals have accumulated toxins, adding powdered murunga-seed to water may pollute the water even more! All this shows that before we apply some "magic remedy", or adopt some "trick" triumphantly broadcast by false "internet gurus" like Dr. Mercola, we need to follow the standard route of scientific investigations. These will include a chemical analysis of the murunga pods before use in the water, and a chemical analysis of the water as well as the filtered sludge, especially for Cd, As, Fluoride etc., at parts per billion accuracy before the method can be applied for public use. In Bangladesh, well-meaning international organizations installed "free" tube wells for providing water to rural people, without a chemical analysis of the water obtained from the tube wells. Unfortunately, the tube-well water contained high levels of arsenic, creating a human catastrophe which has gone on for decades. In Sri Lanka, an expensive high-tech water filtration process known as Reverse-Osmosis (RO), often used to purify sea water, was introduced at great cost for giving "clean water" to the residents in the NCP, when it was later found by a team of engineers of the National Water Board that the input water was already quite clean (i.e., no significant amounts of toxins) and did not need expensive RO installations! However, the people have become panicked by the propaganda about the presence of toxins ("Vasha-Visha") and buy RO water at prices ranging from Rs 0.25 to Rs 1.0 per liter, compared to Colombo citizens who get potable piped water for a "thuttuwa".

As we see, even RO water is cheaper than water cleaned using Murunga-seed powder, costing Rs1.50 per liter of water! The cheapest and fastest way to provide clean water to the NCP is to harvest rain water, successfully used even in Uganda where the rainfall is a tenth of that in the NCP. A large (plastic) tank is needed and this initial cost (about Rs. 50,000-70,000 per family) can be amortized over 20-30 years. Then a liter of clean water costs less than one cent. Several organizations in Sri Lanka have experience in this, and are helping the NCP residents to harvest their rainwater, while leaving Murunga to the elite organic-food lobby.

Chandre Dharmawardana,
Ottawa, Canada.

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