How glyphosate could be linked to cancer

January 2014
Photo of farm vehicle spraing a field of crops
CC photo of crop spraying in Norfolk - via timparkinson on Flickr
While pro-GM scientists, regulators and industry rally to find reasons to dismiss the science suggesting an increased incidence of tumours in rats fed glyphosate herbicide [1], other studies on the subject are being quietly published.
Scientists at the Indian Institute of Toxicology in Lucknow, have previously reported that glyphosate has tumour-promoting potential in a mouse skin model.  Further investigation, using cultured human skin cells as a 'normal' model, have identified the underlying mechanism.  It seems glyphosate interferes with calcium-ion dependent processes inside the cell.
Calcium plays a pivotal part of the regulation of many key cellular activities including cell development, proliferation, secretion, gene activation, and natural cell death.
While glyphosate as a pure chemical is known to bind to metal ions, any effects inside the cell, where calcium is bound to proteins and may be associated with membranes, are too complex to predict.  However, the Indian team's experiments demonstrated that the herbicide does indeed disrupt calcium function within the cell.

They identified a glyphosate-induced calcium depletion in their cells, along with suppression of vital calcium-dependent enzymes.  Knock-on effects included a down-regulation of the processes leading to natural cell death, and the generation of toxins (reactive oxygen species) by the cells.  These toxins are known to cause cell dysfunction and malignant transformation. 
Their studies on skin cells exposed to glyphosate showed clear dose- and time-dependent effects.  At low levels, the herbicide induced cell proliferation which, in conjunction with a failure of normal cell death, could link to tumour formation, and set the scene for cancer.  At higher levels, glyphosate is toxic and the exposed cells decline.
In  June 2013, Friendsof the Earth and GM Freeze published the results of Europe-wide tests for glyphosate levels in humans.  Urine samples were obtained from 182 volunteers in 18 countries across Europe, including 10 from the UK.  All the volunteers lived in cities and none had handled nor used glyphosate products in the run up the testing.   On average 44 per cent of samples contained traces of glyphosate (70 per cent in the UK).
Glyphosate is used on many crops before harvest and accumulates in many GM crops with inserted glyphosate-tolerance genes.  It can reach ground-water by a number of routes.  Despite this, its presence food, feed and water is rarely monitored.


A substance to which our bodies may be continually exposed, and which can disrupt cell function at such a fundamental level as its calcium balance, could be very damaging indeed.
Glyphosate toxicity studies have always focused on acute toxic effects which only occur at higher doses and have enabled the herbicide to be marketed with a 'safe-as-salt' image [2].  Clearly, lower, non-toxic, 'safe' doses have a real carcinogenic potential. The possibility of a direct link between glyphosate exposure and increasing cancer incidence [3], promoted by escalating levels in the GM food chain seems ever more likely.
Just another reason (if you needed one) not to eat GM food.  It also might be a reason to start pressuring the Department of the Environment and Rural Affairs to disallow the practice of spraying glyphosate on (non-GM) crops as a harvesting aid.

[2] GLYHPOSATE - SAFE AS SALT? - (Document link) GMFS Archive, February 2009

[3]  US PUBLIC HEALTH TRENDS AFTER GM - October 2013    

Jasmine George and Yogeshwer Shukla, 2013, Emptying of Intracellular Calcium Pool and Oxidative Stress Imbalance Are Associated with the Glyphosate-induced Proliferation in Human Skin keratinocytes HaCaT Cells,  ISRN Dermatology

Jasmine George et al., 2010, Studies on glyhphosate-induced carcinogenicity in mouse skin: A proteomic approach, Journal of Proteomics 73:5

GovernmentUrged to Act After Weedkiller Traces Found in Britons, GM Freeze and Friends of the Earth Press Release, 13.06.13

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