UK scientists say they have conducted an unprecedented, long-term study showing a link between Roundup - one of the most widely used herbicides in the world - and severe liver damage in test rats.
The research sparked further debate in the international scientific community over the potential health hazards to people caused by exposure to the well-known weed killer.
Scientists from King's College London, whose findings were published in the journal, Nature , earlier this month, said their tests used cutting-edge technology to demonstrate that "extremely low doses" of the herbicide administered to rats through their drinking water had caused "non-alcoholic fatty liver disease (NAFLD)" over a two-year period.
NAFLD can lead to more serious liver disease such as cirrhosis, and increases the risk of other illnesses including diabetes, heart attacks and strokes.
"The study is unique in that it is the first to show a causative link between consumption of Roundup at a real-world environmental dose and a serious disease condition," the report said.
In recent years, there have been an increasing number of studies alleging links between herbicides - used to help grow genetically modified crops - to a wide range of health issues including birth defects, reproductive and neurological problems, cancer, and even DNA damage.
Monsanto, the maker of Roundup, has repeatedly denied the accusations , insisting the product is safe for humans.
A number of scientists and researchers say there has been insufficient evidence to prove herbicides cause health problems for people.
“We know Roundup, the commercial name of glyphosate based herbicides, contains many other chemicals which, when mixed together, are 1,000 times more toxic than glyphosate on its own,” he stated at the meeting."
NAFLD currently affects 25% of the US population and similar numbers of Europeans. Risk factors include being overweight or obese, having diabetes, or having high cholesterol or high triglycerides (a constituent of body fat) in the blood. However, some people develop NAFLD even if they do not have any of these known risk factors. The new study raises the question of whether exposure to Roundup is a hitherto unrecognized risk factor.