Farmers in developing countries are dying in their thousands from a mysterious kidney disorder, which has been termed as "Chronic Kidney Disease of Unknown Etiology" (CKDu).

The disease is running rife through farmers from the rice paddy regions of Sri Lanka, and in El Salavdor, it is the second leading cause of death among male adults, posing a greater risk to health there than diabetes, AIDS, and leukemia combined. A new study has now linked the unexplained deaths to the use of a herbicide patented by the giant biochemical company, Monsanto.

The CKDu originally manifested in Sri Lanka a couple of decades ago, and has spread rapidly throughout the country’s farming communities where it now affects up to fifteen per cent of adults. Over the years, 400,000 people have been affected and 20,000 have died from the disease. The Sri Lankan Ministry of Health reported that the condition did not appear to follow risk factors normally associated with chronic kidney diseases, such as diabetes, hypertension or kidney inflammation.

The recent study, which was published in the Swiss-based International Journal of Environmental Research and Public Health, may now be able to explain how the CKDu develops: it has suggested that a widely used glyphosate-based herbicide can become a fatal brew once it is combined with the metals often contained in hard water or soil, and that the resulting toxic compounds can destroy kidney tissue.

Soil can contain metals such as arsenic and cadmium, and the metal content of hard water can be made up of many different elements, including calcium, magnesium, strontium, and iron. The study states that glyphosate, a molecule patented as a herbicide by Monsanto in the 1970s, can form “strong complexes with metal ions,” complexes that are capable of retaining nephrotoxic metals and delivering them to the kidney. Glyphosate is an toxic molecule in its own right, but is not harmful enough to cause the type of deleterious effect on kidney tissue observed in CKDu. Combined with other metal elements, however, it appears to become a deadly poison. The herbicide, known commercially as "Roundup," can be easily ingested via consumption of contaminated hard water, in food, or through the skin. The findings of the study, which was conducted by Channa Jayasumana (Rajarata University, Sri Lanka), Sarath Gunatilake (California State University, USA) and Priyantha Senanayake (Hela Suwaya Organization, Sri Lanka), indicated that up to 96 per cent of patients had consumed “hard or very hard water for at least five years, from wells that receive their supply from shallow regolith aquifers.”

"The phosphorous atom in the phosphonic group in the glyphosate/AMPA molecule can possibly be replaced by As (Arsenic)," an excerpt from the study explained. "Following dermal and respiratory absorption of glyphosate, it can form complexes with nephrotoxic metals and As derived from rice, vegetables and tobacco within the circulation."

Glyphosate-metal complexes (GMCs) are not evacuated via normal liver’s detoxification process, and the researchers believe that the toxic complexes may accumulate in the body over a long period of time, so that it could take many years before signs of the CKDu are observed in affected individuals. This hypothesis is based on the fact that agrochemicals have been used in the affected areas since the 1970s, but the CKDu did not begin to afflict the population until the 1990s.

The spread of the disease is thought to be due to the fact that glyphosate is easily ingested through a variety of different means, and also because, once it has reacted to form hard complexes, its half-life can increase from 47 days up to 22 years. This means that it can potentially accumulate in increasingly large amounts, multiplying the risk of exposure, a fact of even greater concern when one considers that it is used in copious quantities throughout countries like Sri Lanka.

The researchers noted that Roundup is used alongside triple-super-phosphate (TSP) fertilizer which contains arsenic and heavy metals.

"…Within a couple of weeks after the spraying of glyphosate farmers apply triple phosphate (TSP) to the paddy fields," said the authors. "Recent findings have shown that the TSP available in Sri Lanka is contaminated with significant amounts of Cd (Cadmium), Cr (Cromium), Ni (Nickel) and Pb (lead). Furthermore, it was also found that TSP used in Sri Lanka is a very rich source of arsenic."

According to the study, even the World Health Organisation had associated the CKDu with arsenic, cadmium and pesticide contamination, along with hard water consumption. It also proposed that other outbreaks of kidney disorders in Nicaragua, Costa Rica and Andra Pradesh in India, could also be attributed to the use of Roundup.

A series of articles published in the journal Science last year claimed that developing countries need stronger pesticide regulation, and an international body to carry out regular pesticide safety assessments. The special report suggested that new technologies must be developed in order to make pesticides safer, ultimately producing crops that will not require pesticides at all.

Jeffery Dangl, a biology professor at the University of North Carolina, United States, and his colleagues, revealed advances in the understanding of plant immune systems and DNA sequencing that have allowed the production of crops that are less susceptible to pests and disease.

"We lose 20 to 30 per cent of our global food supply to pests and pathogens every year," Dangl told SciDev.Net. "If you reduce plant diseases and recover that, you could feed 20 to 30 per cent more calories to people."

The research could potentially have the greatest impact in developing countries, where currently there is poor regulation of pesticide use.

"One often sees farmers throwing chemicals on their plants, using their hands, and without proper clothing, and they often use fungicides and pesticides that are no longer allowed in the developed world," explained Dangl. "There’s poor regulation and poor administration of the regulation."

Reducing contamination of the environment and food by pesticides would seem to be a very positive step forward in farming, though engineering such pesticide-resistant crops would surely require some genetic modification to achieve that result. This fact that could prove to be an emotive issue for those opposed to GM foods, an issue that has provoked strong reactions over the past few decades.

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