Effects of Chronic Exposure to Glyphosate at Very Low Doses in Rats

Item 1 


Robin Mesnage, Matthew Arno, Manuela Costanzo, Manuela Malatesta, Gilles-Eric Séralini and Michael N Antoniou
Environ Health,  doi: 10.1186/s12940-015-0056-1.
http://www.ehjournal.net/content/14/1/70 (Open Access) 


Background: Glyphosate-based herbicides (GBH) are the major pesticides used worldwide. Converging evidence suggests that GBH, such as Roundup, pose a particular health risk to liver and kidneys although low environmentally relevant doses have not been examined. To address this issue, a 2-year study in rats administering 0.1 ppb Roundup (50 ng/L glyphosate equivalent) via drinking water (giving a daily intake of 4 ng/kg bw/day of glyphosate) was conducted. A marked increased incidence of anatomorphological and blood/urine biochemical changes was indicative of liver and kidney structure and functional pathology. In order to confirm these findings we have conducted a transcriptome microarray analysis of the liver and kidneys from these same animals. 

Results: The expression of 4224 and 4447 transcript clusters (a group of probes corresponding to a known or putative gene) were found to be altered respectively in liver and kidney (p < 0.01, q < 0.08). Changes in gene expression varied from −3.5 to 3.7 fold in liver and from −4.3 to 5.3 in kidneys. Among the 1319 transcript clusters whose expression was altered in both tissues, ontological enrichment in 3 functional categories among 868 genes were found. First, genes involved in mRNA splicing and small nucleolar RNA were mostly upregulated, suggesting disruption of normal spliceosome activity. Electron microscopic analysis of hepatocytes confirmed nucleolar structural disruption. Second, genes controlling chromatin structure (especially histone-lysine N-methyltransferases) were mostly upregulated. Third, genes related to respiratory chain complex I and the tricarboxylic acid cycle were mostly downregulated. Pathway analysis suggests a modulation of the mTOR and phosphatidylinositol signaling pathways. Gene disturbances associated with the chronic administration of ultra-low dose Roundup reflect a liver and kidney lipotoxic condition and increased cellular growth that may be linked with regeneration in response to toxic effects causing damage to tissues. Observed alterations in gene expression were consistent with fibrosis, necrosis, phospholipidosis, mitochondrial membrane dysfunction and ischemia, which correlate with and thus confirm observations of pathology made at an anatomical, histological and biochemical level. 

Conclusion: Our results suggest that chronic exposure to a GBH in an established laboratory animal toxicity model system at an ultra-low, environmental dose can result in liver and kidney damage with potential significant health implications for animal and human populations.

Item 2  


*Summary of the above study by Robin Mesnage, Matthew Arno, Manuela Costanzo, Manuela Malatesta, Gilles-Eric Séralini and Michael N Antoniou 

A new peer-reviewed study led by Dr. Michael Antoniou at King’s College London describes the effects on gene function of a very low dose of Roundup weedkiller administered to rats over a 2-year period. The study is unique in that it is the first to look at effects of Roundup on gene expression at environmentally relevant doses. The study confirmed that levels of Roundup that may be found in drinking water can cause liver and kidney damage following long-term consumption.        

Background to study

This experiment was a follow up investigation of the long-term (2-year) toxicity study in rats of Roundup conducted by Gilles-EricSeralini and colleagues (Seralini et al., 2014).

The original investigation administered a commercial Roundup formulation at 0.1ppb (parts per billion)/50ppt (parts per trillion) glyphosate via drinking water for 2 years.

Analysis at an anatomical (organ) and blood/urine biochemical level suggested a higher incidence of liver and kidney damage in the Roundup treatment group compared to the control. Liver and kidney pathologies were also present in the control group due to the advanced age of the animals, but at a lower frequency. 

Purpose of current study

Different patterns of gene function; i.e., which genes are turned off or on and at what level, are known to underlie health and disease status of an organ system. We wanted to investigate whether heightened liver and kidney pathology observed at an anatomical and biochemical level was reflected in the gene expression pattern. Therefore we analysed the pattern of gene function (“transcriptome”), by comparing liver and kidney tissues from the Roundup treatment group with those of the control animals. 


A distinct and consistent alteration in the pattern of gene function was found in both the liver and kidneys of the Roundup treatment group.

A large number (over 4000) of genes were found to be either increased or decreased in function,with many (over 1300) being similarly affected in both organs.

These changes in gene function were consistent between animals and were highly statistically significant. 

A computational (“bioinformatics”) analysis of the alterations in gene function linked these changes to numerous biochemical systems involved in regulating gene expression, respiration, and disturbances in fat metabolism.  

The alterations in gene function were consistent with fibrosis (scarring), necrosis (areas of dead tissue), phospholipidosis (disturbed fat metabolism)and damage to mitochondria (the centres of respiration in cells).

These changes correlate with and thus confirm observations of pathology made at an anatomical, histological (microscopic cellular) and blood/urine biochemical level. 


The glyphosate equivalent dose of Roundup administered in this study is what may be found in drinking water. It is half that permitted in drinking water in the European Union and Australia, and 14,000 times lower than that permitted in drinking water in the USA.

The amount of glyphosate-equivalent Roundup consumed by the animals on a daily basis was many thousands of times below the regulatory set safety limits of glyphosate alone in all regions around the world.

The observed liver and kidney pathologies may have arisen from glyphosate, the adjuvants present in the Roundup formulation, or acombination of the two.

The mechanism by which the Roundup induced this heightened pathology is unknown, but given the extremely low dose at which these effects are observed, this could be through endocrine (hormone system) disruption. 

Relevance to health

These results suggest that long-term consumption of an ultra-low, environmentally relevant dose of Roundup at a glyphosate-equivalent concentration of only 50ppt (parts per trillion) in an established laboratory animal toxicity model system can result in liver and kidney damage, with potential significant health implications for human, domesticated animal and wildlife populations. 

Quote from lead author Dr Michael Antoniou:

“The findings of our study are very worrying as they confirm that a very low level of consumption of Roundup weedkiller over the long term can result in liver and kidney damage. Our results also suggest that regulators should re-consider the safety evaluation of glyphosate-based herbicides.”

Item 3 


by R. Mesnage, N. Defarge, J. Spiroux de Vendomois, G.E. Seralini

Glyphosate-based herbicides (GlyBH), including Roundup, are the most widely used pesticides worldwide. Their uses have increased exponentially since their introduction on the market. Residue levels in food or water, as well as human exposures, are escalating. We have reviewed the toxic effects of GlyBH measured below regulatory limits by evaluating the published literature and regulatory reports. We reveal a coherent body of evidence indicating that GlyBH could be toxic below the regulatory lowest observed adverse effect level for chronic toxic effects. It includes teratogenic, tumorigenic and hepatorenal effects. They could be explained by endocrine disruption and oxidative stress, causing metabolic alterations, depending on dose and exposure time. Some effects were detected in the range of the recommended acceptable daily intake. Toxic effects of commercial formulations can also be explained by GlyBH adjuvants, which have their own toxicity, but also enhance glyphosate toxicity. These challenge the assumption of safety of GlyBH at the levels at which they contaminate food and the environment, albeit these levels may fall below regulatory thresholds. Neurodevelopmental, reproductive, and transgenerational effects of GlyBH must be revisited, since a growing body of knowledge suggests the predominance of endocrine disrupting mechanisms caused by environmentally relevant levels of exposure.

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