The mystery kidney disease is mostly found in areas with 'hard' ground water (water containing Calcium, Magnesium, Strontium and Iron and other chemicals) except in Sri Lanka's northern province where the ground water is also hard.
N-(phosphonomethyl) glycine a widely used herbicide better known as glyphosate, could be helping carry heavy metals toxic to kidneys, occurring naturally and in agro-chemicals such as phosphate fertilizer, the researchers said.
Chronic kidney disease of unknown etiology (CKDu) first appeared in Sri Lanka's rice growing areas in the north central province in the 1990s and has been spreading into other areas including the South, with over 20,000 estimated deaths so far.
Glyphosate was originally used as a de-scaling agent to clean out calcium and other mineral deposits in hot water systems, the study said.
De-scaling agents tie themselves to on metals like Calcium and Magnesium and makes them water soluble.It was later sold as a herbicide by US-based Monsanto under the brand name 'Round up' and was under patent until 2000. By 2012 China became the largest producer of glyphosate in the world.
Other researchers have earlier found Arsenic in hair and nails of victims and even healthy individuals in the affected areas.
The researchers cite findings saying the affected rice growing areas are naturally rich in heavy metals including Nickel, Chromium, Cobalt and others.
The chemical could also be ingested into the body through other ways.
The researchers said farmers in Sri Lanka do not use protective gear and glyphosate is also dissolved in hard water before spraying. They have detected Glyphosate in their urine after spraying.
The compound can be breathed in and get into the body through the skin after dissolving in sweat, the paper said.
Other research had found Cadmium and Arsenic in rice and tobacco grown in Sri Lanka. Farmers also ate rice as a staple and also chewed tobacco.
"The phosphorous atom in the phosphonic group in the glyphosate/AMPA molecule can possibly be replaced by As (Arsenic)," the researchers said.
"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."