Effects found at doses considered safe by regulatory agencies

A multi-institutional international toxicological study has found that low doses of glyphosate-based herbicides cause leukemia in rats. Importantly, half of the leukemia deaths identified in the study groups occurred at an early age.

The first carcinogenicity data from the Global Glyphosate Study (GGS) were presented on Wednesday at the international scientific conference, "Environment, Work and Health in the 21st Century: Strategies and Solutions to a Global Crisis", in Bologna, Italy.

Glyphosate is the world’s most used weedkiller and is found regularly in food, water and human samples.

In this long-term study, glyphosate alone and two commercial formulations, Roundup BioFlow (MON 52276) used in the EU and Ranger Pro (EPA 524-517) used in the US, were administered to rats via drinking water beginning in prenatal life, at doses of 0.5, 5, and 50 mg/kg body weight/day. These doses are currently considered safe by regulatory agencies and correspond to the EU Acceptable Daily Intake (ADI), the EU ADI x 10, and the EU’s No Observed Adverse Effect Level (NOAEL) for glyphosate.

Dr Daniele Mandrioli, the coordinator of the Global Glyphosate Study and the Director of the Ramazzini Institute, stated on Wednesday that “About half of the leukemia deaths seen in the rats exposed to glyphosate and glyphosate-based herbicides occurred at less than one year of age. By contrast no cases of leukemia have been observed below one year of age in more than 1600 Sprague-Dawley rats studied over the past two decades by the US National Toxicology Program (NTP) and the Ramazzini Institute.”

The GGS is the most comprehensive toxicological study ever conducted on glyphosate and glyphosate-based herbicides. It provides vital data for government regulators, policy makers and the general public. It examines the impacts of glyphosate and glyphosate-based herbicides on carcinogenicity, neurotoxicity, multi-generational effects, organ toxicity, endocrine disruption and prenatal developmental toxicity. Multiple peer-reviewed papers from the study are set to be published from early 2024 onwards.

“These findings are of such great relevance for public health that we decided it was vital to present them now in advance of publication. The full data will be made publicly available and submitted for publication in a scientific journal in the coming weeks,” Dr Mandrioli concluded.

The GGS’s findings on glyphosate’s toxicity to the microbiome, which were peer-reviewed and published in late 2022 and presented at the EU Parliament in 2023, also showed adverse effects at doses that are currently considered safe in the EU (0.5 mg/kg bw/day, equivalent to the EU Acceptable Daily Intake).

The GGS previously published a pilot study, which showed endocrine and reproductive toxicity in rats at glyphosate doses currently considered safe by regulatory agencies in the US (1.75 mg/kg bw/day). These findings were later confirmed in a human population of mothers and newborns exposed to glyphosate during pregnancy.

This multi-institutional study, coordinated by the Ramazzini Institute, involves scientists from Europe, the U.S. and South America, giving extra weight to the results. Scientists are involved in the study from the Icahn School of Medicine at Mount Sinai, George Mason University, University of Bologna, University of Copenhagen, Boston College, Italian National Institute of Health, Federal University of Parana, University of California Santa Cruz and Genoa Hospital San Martino.

Source: Ramazzini Institute/Global Glyphosate Study