The study, published in the journal Environmental Health, found that continuous exposure to very low doses of the herbicide Roundup might be linked to liver and kidney damage.
The researchers looked at how genes changed in rats that were given a commercial Roundup formulation containing 0.1 parts per billion of glyphosate (the active ingredient in Roundup) over a two-year period.
The amount of glyphosate the rats were exposed to was well below what is allowed in U.S. drinking water today. The “maximum contaminant level goal” for glyphosate in U.S. drinking water is set at 700 parts per billion.
The researchers found “a distinct and consistent alteration in the pattern of gene expression” in both the liver and kidneys of the rats given low doses of Roundup.
Researchers often use animal studies to determine whether there is cause for concern for human exposure. The researchers say their findings show “potential significant health implications for human, domesticated animals and wildlife populations.”
The study was led by Michael Antoniou of the Nuclear Biology Group at King’s College London.
“The findings of our study are very worrying as they confirm that a very low level of consumption of Roundup weed killer over the long term can result in liver and kidney damage,” Antoniou said in a statement. “Our results also suggest that regulators should re-consider the safety evaluation of glyphosate-based herbicides.”
The researchers suspect exposure to Roundup caused changes in the rats’ hormonal system (the endocrine system). They say the damage could have come from the active ingredient in Roundup, glyphosate, other chemicals in the Roundup formulation, or the combination of chemicals.
This study follows up on a controversial Roundup study by another group published in 2012 that found liver and kidney damage in rats.
More from Brian Bienkowski of Environmental Health News.
In the 2012 study, different groups of rats were fed mixtures of genetically modified corn and Roundup. Researchers, led by Gilles-Éric Séralini, a professor of molecular biology at the University of Caen in France, reported cancers and other health impacts from both the corn itself and the herbicide.
But the experiment design and results were highly controversial; the paper was retracted and eventually republished last year …
In the current study, Antoniou and colleagues compared the female mice from the 2012 group and found big differences in their genes compared to rats that were not fed Roundup.
Roundup is a widely-used herbicide. Monsanto, the maker of Roundup, produces genetically modified “Roundup-Ready” crops that are resistant to the herbicide. It allows farmers to widely spray the herbicide on their corn, cotton, and soybean crops to control weeds without damaging their crops.
These types of crops today account for more than 92-94% of all the cotton, corn, and soybeans grown in the U.S. today, according to the U.S. Department of Agriculture.
Monsanto did not respond to a request for an interview. The company’s website says “glyphosate-based” herbicides have been extensively studied and are safe when used correctly.
California, in the meantime, is considering listing glyphosate as a chemical “known to the state to cause cancer.”