London (27.8.10) – Glyphosate was first introduced as a broad-spectrum systemic weedkiller some 40 years ago, very effective at dealing with a wide variety of grasses, broadleaf, and woody plants. Under its trade name “Roundup” it is widely used in agriculture, horticulture, silviculture and gardening. In the U.S. it is the most widely used herbicide.

Glyphosate has been rated least dangerous in comparison to other herbicides and pesticides, such as those from the organochlorine family. Roundup has a U.S. Environmental Protection Agency (EPA) Toxicity Class of III for oral and inhalation exposure. It has been rated as class I (Severe) for eye irritation (1).

In a new paper, a group of workers in Argentina (2) cast doubt on its lack of toxicity. Earlier reports of neural defects and craniofacial malformations from regions where glyphosate-based herbicides were used led the authors to undertake an embryological study of the effect of low doses of glyphosate on the development both of the African clawed frog Xenopus laevis and of chicken embryos. The method they used was to inject pure glyphosate together with adjuvant directly into the embryos, certainly a vigorous procedure in their determination to explore toxicity effects.

Sure enough, both the frog and the chick embryos were “highly abnormal”, leading the authors to worry about the clinical findings from human offspring in populations exposed to glyphosate-based herbicides in agricultural fields.

These are indeed worrying findings but not, perhaps, quite so worrying as one might imagine. Professor Wayne Parrott of the University of Georgia was doubtful because he could not see that proper controls had been performed. His view was that, for all we know, the experimenters could have injected holy water into the embryos and obtained the same effect. Injecting either Roundup or glyphosate gave similar results which begs the question: what would have happened if they had injected adjuvant instead? How do they know it was not the effect of injection itself that caused the problem? Moreover, no hypothesis was offered to explain the glyphosate action.

Dr. Parrott’s view is that even if the results are properly confirmed, the average woman probably has little to worry about as long as she does not inject Roundup into her embryos. “After all”, he said, “a toxin cannot cause damage if there is no exposure. The ‘information’ in the discussion section of the paper (about the human consequences of the use of herbicides) and pesticides is not referenced, and hence must be considered anecdotal or hearsay”.

The authors quote an epidemiological study in Paraguay which claimed that the offspring of women exposed during pregnancy to herbicides showed 52 cases of malformations (3, 4). But the chemicals in the Paraguay study (described in the title of the paper as “agrotoxics”) were not necessarily glyphosate, and they do not give the rate of malformations in the control group. This one sentence in Professor Parrott’s view is a gross misrepresentation of data and there may be some way to go before we may have confidence in the toxicity conclusion, particularly as the authors agree that “Further studies are required to confirm these findings….”

Incidentally and curiously, something similar was reported 15 years ago when scientists at the Safety laboratory of Tanabe Seiyaku Company in Osaka found that both caffeine and phenobarbital caused cardiovascular malformations in chicken embryos (5). Professor Parrott may not have been that far out with his comment about holy water.

It seems that the response to the glyphosate paper has provoked strong reactions in various quarters. Amnesty International reports that “community activists from La Leonesa, a small town located within an area of large scale rice production in the Argentinean Chaco Department, went to attend a talk that was to be given by Professor Andres Carrasco (one of the authors of the glyphosate toxicity paper), a scientist and doctor from the Buenos Aires University Medical School….. A delegation (comprising two provincial deputies, a former public official and members of the neighboring community) came to La Leonesa to hear the talk.) However, the talk was suspended because the delegation was attacked by a group of around 100 people who threatened them and beat them.”

Amnesty has put out an “Urgent Action” appeal (4) calling for an impartial investigation of the violence (but not of the paper), swift action to ensure local safety and security, protection by the local authorities of the right to freedom of expression and, where credible evidence exists of the negative effects of the spraying of agro-chemicals, for the authorities to monitor and investigate.

It is always right to protect freedom of expression and of people carrying out their legitimate activities within the law. We therefore await with interest similar appeals by Amnesty International in support of the genetically modified apple trees destroyed by anti-GM activists at the Julius Kühn Institute in Germany (6) even though they were in a special safety tent, of a GM-wheat field trial destroyed in Saxony-Anhalt (7), genetically modified grapes wrecked by anti-GM protesters at a government research site in France (8) and, indeed, of the farmer in Italy whose field of Bt-maize was destroyed and placards left behind bearing a skull and crossbones and reading: “Danger — Contaminated — G.M.O.” (9).

They are just the beginning; when Amnesty has appealed about those cases there are many more waiting for them.


1. Glyphosate. Wikipedia (

2. Alejandra Paganelli, Victoria Gnazzo, Helena Acosta, Silvia L. López and Andrés E. Carrasco (9.8.2010). Glyphosate-based herbicides produce teratogenic effects on vertebrates by impairing retinoic acid signaling. Chemical Research in Toxicology (

3. Benítez Leite, S., Macchi, M. A., and Acosta, M. (2009) Malformaciones Congénitas asociadas a agrotóxicos. Archivos de Pediatría del Uruguay, 80(3), 237–246 (

4. Fear for safety – Argentina: Community activists in La Leonesa. Amnesty USA (12.8.10) (

5. T. Kobayashi, A. Nishida, A. Kurokawa and F. Ariyuki (1995). Cardiovascular malformations indiced by caffeine and phenobarbital in chick embryos. AATEX (Alternatives to Animal Testing and Experimentation), 3, 17 (

6. Apple trees destroyed. GMO Safety (3.6.09) (

7. Wheat field trial destruction: GM opponents must pay. GMO Compass (19.6.09) (

8. French protesters destroy biotech grapevines. Taiwan News (15.8.10) (

9. Elizabeth Rosenthal (23.8.10). In the fields of Italy, a conflict over corn. New York Times (


  Another scare: this time it’s glyphosate