Glyphosate - Research and References
In March 2015, the International Agency for Research on Cancer (part of the World Health Organisation), published a report in which glyphosate was identified as a ‘probable carcinogen’ to humans.
There is a maximum residue level (MRL) set for glyphosate, and the residues found in bread do fall below the current MRL; however this level has not been reviewed since the IARC’s announcement.
About the IARC Report
The IARCs decision was made by 17 scientists led by Aaron Blair—an internationally renowned epidemiologist who spent thirty years at the National Cancer Institute, and the author of more than 450 scientific papers.
How did IARC reach this decision?
Three types of data were reviewed: epidemiological studies on humans who had been repeatedly exposed to glyphosate; lab tests on animals; and “mechanistic” analyses, which analyse how a compound can actually cause cancer in our bodies. The animal studies “found excesses of rare tumours”. This was supported by the human studies, which showed “a strong link between people who used or were around glyphosate, and an increased risk of non-Hodgkin’s lymphoma” .
Why not a ‘definite’ carcinogen?
According to lead scientist Aaron Blair, there were good grounds to conclude this . But one of the many human studies did not find a link between people who use glyphosate and the emergence of cancers, so this category was not chosen. Time will tell: The picture may become clearer as more studies are done, as it did in the case of benzene – now universally acknowledged as carcinogenic.
Is glyphosate dangerous below current regulatory limits?
Pesticide industry representatives have implied that, as IARC only evaluates hazards, not the risks associated with exposure, their conclusion only applies to extreme levels well above current regulatory limits. But IARC has identified a totally new hazard – carcinogenicity – and this raises new questions about what level is safe; both the EU and US risk assessments were done before this new hazard was found.
The industry’s claim ignores the fact that the studies IARC examined included low levels of glyphosate exposure. Current regulatory limits need urgent re-assessing.
Glyphosate herbicide operators
IARC found that the studies which showed the clearest link between glyphosate and cancers in humans concerned operators using glyphosate herbicides. This seriously calls into question the safety of farmers and workers who regularly use glyphosate products in their jobs.
New studies that support IARC’s conclusion
Alongside the concerns laid out by IARC, two new studies suggest that the daily consumption of very low levels of glyphosate may indeed pose a health risk. According to UK government data, the average level of glyphosate found in bread is around 0.2mg in up to a third of bread. Given the average amount of bread eaten daily and the average bodyweight of a UK adult, the average person therefore consumes around 78ng of glyphosate per kg body weight every day. This is nearly 20 times the level found to cause liver and kidney damage in one of the recent animal studies (only 4ng per kg body weight per day) .
Damage to gene functions leading to organ damage
Research animals were given Round-up, Monsanto’s patented glyphosate based product, on a daily basis, at a dose equivalent to half the levels permitted in drinking water in the European Union—thousands of times below the regulatory set safety limits of glyphosate alone. The study concluded:
"A distinct and consistent alteration in the pattern of gene expression was found in both the liver and kidneys of the Roundup treatment group ... these 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)" .
Liver and kidney damage at ultra-low environmental doses
A review of regulatory reports and published literature found around 30 studies that indicate glyphosate-based herbicides have toxic effects below regulatory limits. This included studies performed by chemical companies on their own products, and studies looking at the impact of Roundup at a concentration of 0.1 parts per billion, with a glyphosate concentration half that allowed in drinking water by the European Union. The researchers concluded:
"Our results suggest that chronic exposure to a GBH [Glyphosate-based herbicide] 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".
Why did IARC reach a different conclusion to US and EU regulatory bodies?
Regulatory bodies frequently only look at studies undertaken by the pesticide companies themselves. Because these studies are commercially confidential, they are not subject to the normal scientific process of peer review and open publication in the scientific literature, and they are not available for public scrutiny. Importantly, all regulatory bodies, including in the EU, only consider scientific research on the effects of the pure chemical – in this case glyphosate – rather the final product mixtures that farmers, gardeners and many others actually use. By contrast, the IARC reviewed only publically available peer-reviewed studies, and this included studies of actual glyphosate based products like Round-up, as used by those most at risk. Despite what pesticide industry representatives claim, this makes IARC’s results far more relevant when assessing real risk.
What’s the difference between pure glyphosate & glyphosate herbicide products?
Glyphosate as a pure chemical is very rarely used as a herbicide. Instead, it is mixed with other chemicals, known as adjuvants. These improve the efficacy of products – for example easing spraying or ensuring the product sticks to the plant. These mixtures may interact to have an adverse combined effect. Furthermore, whilst these adjuvants are considered ‘inert’, research has shown that some are, themselves, toxic. However, as they are not named by the chemical company as the main ingredient, they are not subject to the same safety testing. Research has shown that glyphosate with adjuvants may be many times more toxic than glyphosate alone .
- [1,2] Interview with Aaron Blair, Ph.D., M.P.H. in Harper Magazine ‘Weed Whackers: Monsanto, glyphosate, and the war on invasive species’, Andrew Cockburn http://harpers.org/archive/2015/09/weed-whackers/7/
- [3,4] 'Transcriptome analysis reflects rat liver and kidney damage following chronic ultra-low dose Roundup exposure' (2015 Environ Health, 2015 Aug 25; 14(1): 70. doi: 10.1186/s12940-015-0056-1)
-  ‘Potential toxic effects of glyphosate and its commercial formulations below regulatory limits’; (Oct 2015; Food and Chemical Toxicology, 84: 133-153) http://www.sciencedirect.com/science/article/pii/S027869151530034X
-  ‘Major Pesticides Are More Toxic to Human Cells Than Their Declared Active Principles’, (Biomed research International, Feb 2014; 2014(2014) Article ID 179691 http://www.hindawi.com/journals/bmri/2014/179691/abs/