Roundup hurts hearts?

January 2015
Pesticide spraying. CC photo by Global Water Partnership on Flickr
There could be as many as five million agricultural workers in the developing world who suffer an episode of pesticide poisoning each year. Some of these are accidental and some are, sadly, due to attempted suicide. In these latter cases, death is strongly associated with high blood glyphosate levels. Glyphosate is, of course, the active ingredient of Roundup herbicide used on, and accumulated by, GM 'Roundup Ready' crops.
Roundup intoxication commonly leads to heart malfunction. Anecdotal evidence from hunters describe rabbits dying suddenly after crossing a Roundup-sprayed field, and pet owners have described dogs dying of seizures after exposure to Roundup-sprayed lawns.
Despite these, Roundup's benign image remains intact [1]. But the evidence that the herbicide is far from physiologically inert is mounting.
The latest published Roundup toxicity study sought to explain the link between the herbicide and cardiac function problems.
A French team, led by Steve Gress, investigated what happened when strips of rat and rabbit heart, stimulated to contract by electrical impulses, were exposed to Roundup or its active ingredient, glyphosate. The herbicide used was 'Roundup Ultra' which is freely available in France and which has 36% glyphosate plus 16% of an undeclared adjuvant added to increase the effectiveness of the glyphosate.
What they found was that glyphosate on its own had no effect. Roundup, however, progressively and irreversibly impaired the contractile function of the heart tissue. Further investigations of the mechanism of Roundup damage suggested that the vital flow and exchange of metal ions (sodium, calcium and potassium) in the heart cells was being blocked.
The picture suggested by these findings is that the adjuvants added to Roundup to breach plant protective structures so that the glyphosate can penetrate into the plant cells and kill them, are also able to compromise the integrity of animal cell membranes. Glyphosate, which is inert if kept outside the cell, is thus brought into contact with the cells' metal ions which it binds and immobilises. Roundup's active ingredient may not kill the heart cells, but it could be destroying their function and kill the animal.
The concentrations of Roundup and glyphosate used in this experiment modelled those found in the blood passing through the heart of a suicide or accidental poisoning victim, and was much higher than levels used in routine agriculture. Much of the world's population now seems to be drip-fed Roundup and glyphosate in their food, water and environment [2], but surely the odd dysfunctional heart cell resulting from chronic low-level exposure won't kill anyone.
Or will it?
Bear in mind that: 
  1. Exposure to Roundup and glyphosate starts in the womb and continues throughout life [3]
  2. Our exposure to Roundup is steadily rising due to increasing commercialisation of Roundup Ready food and feed crops, due to increased spraying of such GM crops in response to emerging Roundup-resistant weeds, and due to regulators who have no qualms about setting a maximum residue level (MRL) to suit farmers' desire to spray rather than to safeguard consumers. 
  3. The damaging effect of Roundup on heart cells found in Gress's experiment was irreversible, and therefore cumulative over time. 
No one's going to keel over from heart-failure after eating a few lentils dried down with Roundup, but a lifetime of Roundup gnawing away at your heart cells could be a part of the oddly parallel increase in heart disease and Roundup application now showing up in America [4]. 
We urgently need in-depth scientific testing of the effects of chronic exposure to Roundup on all organ systems, and clinical trails. Keep asking for it. 
[1] GLYPHOSATE: SAFE AS SALT? - GMFS (Archive), February 2009 
  • Steeve Gress, et al., 2014, Cardiotoxic electrophysiological Effects of the Herbicide Roundup in Rat and Rabbit Ventricular Myocardium In Vitro, Cardiovascular Toxicology 2.12.14
  • Rosemary Mason, How Roundup Poisoned my Nature Reserve,  Science in Society 64, Winter 2014


  1. Round Up/glyphosate is being used extensively these days on non-GM crops. It is being used as a "desiccant" or "ripening agent". It is sprayed on shortly before harvest to ensure that all of the crop is ripe i.e. killed to ensure there are no "green" seeds. Major crops being ripened this way include wheat, peas, lentils etc.

    Note that the EPA in the States recently upped the allowable glyphosate residue on crops by almost a factor of 3.

  2. Any glyphosate absorbed has a half life of mere hours in the human body, which is why suicide attempts with glyphosate don't work so well. Ian Forrester is right about it's use as a ripening agent but it's only used where the growing season for the crop at hand is normally too short to ensure the crop is ripe or dry in time. Hence, it's rarely used in the US for ripening, but more so in Canada and, probably, given, Scotland's climate, there too! This means, if it's banned, Scotland will see a decrease in crop production with increases in mold in what is still harvested.

    Ironically, GMO RR crops cannot be ripened with glyphosate as they are unaffected by it. So, if the goal of banning GMO's is to decrease glyphosate in the harvest, doing so may well have the opposite effect.

    But, in any case, the article is dead wrong. No study has ever found any health problems with glyphosate (used for 40 years) that has stood up to peer review.

    One must wonder if there would even be any concern for glyphosate but for its association with GMO's. For instance, Nature has made maize, "Altrazine Ready", a far more toxic, to us, herbicide. Yet, no concern, until, someone GM's another crop to be Altrazine ready. So, all this glyphosate concern is nothing but a front for anti-gmoers to try to get GMO's banned on philosophical grounds, To, wit, to paraphrase Prince Charles, treading on God's domain. Kind of like flying. But we are destined to let slip the surly bonds of Earth.

  3. It’s absolutely right to question things like Roundup/Glyphosate given its prominence, and there’s a whole lot of evidence building up that it’s far from benign.
    There’s so much confusion, stats, and debate and spin it’s hard for folk to understand. Who’s right? Who’s wrong? Well for a start it’s easier to pay attention to independent voices, as opposed to those whose selective scientific evidence has been generously funded by the companies selling the product in question. And then other well-funded peers congratulate and pat each other on the back, and nit-pick and try to stifle debate and inconvenient truths discovered by those looking properly at the full big picture elsewhere. Because that’s how it looks from the outside looking in.

    Personally for me it’s always been about pollution. We can’t keep pumping megatonnes of pollution up into the air, and into the rivers and seas, and lacing the land and our food crops with more and more poisons. And now directly right into DNA and the building blocks of life itself. And then thinking up solutions to problems created that only create more and bigger problems further down the line. Because I’m old enough and have paid enough attention to see with is what keeps happening, especially with techno-fixes – old and new. Just because no one looked at a problem for 40 years doesn’t mean it didn’t exist. One day the planet will be too toxic to live healthily on. Maybe we already reached that day.


Thanks for your comment. All comments are moderated before they are published.