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expert reaction to ‘GMOs, Herbicides, and Public Health’

In an opinion piece in The New England Journal of Medicine, two scientists have recommended that the US delay implementing use of a specific herbicide to be used on GM plants, and also that wider labeling takes place of foods which contain GM components.


Prof. Ottoline Leyser, Director of the Sainsbury Laboratory, University of Cambridge, said:

“The authors make a common mistake in discussions about GM. They have confused GM with a particular application for GM, namely herbicide tolerance. They argue that food should be labelled as GM because of possible risks from the herbicides that can be applied to herbicide tolerant crops. However, many GM crops are not herbicide tolerant, and many herbicide tolerant crops are not GM.

“If the aim of food labeling is to allow consumers to identify products that may contain herbicide residues, there should be labeling to inform consumers about herbicide application.”


Dr Joe Perry, former Chair of the European Food Safety Authority GMO Panel, said:

“The article by Landigran & Benbrook raises several issues, but not all are of concern to European consumers.  In the EU, all GMOs are assessed for toxicity, allergenicity and nutritional quality.  Herbicide resistance in weeds and the indirect effects of herbicides on biodiversity are real potential problems that merit and receive attention when applications to cultivate GM crops in Europe are assessed.

“The remaining issue, the classification by the IARC of glyphosate as a carcinogen, is controversial and not yet accepted by the EU. Within the EU, the toxicity of herbicides such as glyphosate is assessed under different regulations from those of GMOs. However, intensive and independent animal feeding trials* conducted recently found no adverse effects of the consumption of GM crops treated with glyphosate.”

* by the independent GRACE project –


Prof. Huw Jones, Head of Cereal Transformation Lab at Rothamsted Research, said:

“The safe use of herbicides is paramount and appropriate safety measures should prevail. However, herbicides that kill weeds and not crops are everywhere and are not the unique preserve of GMOs. There is no logic in tightening the risk assessment of herbicides only when it involves GMOs. The principle of breeding safe new high-yielding, climate-resilient, pest and disease-resistant crop varieties using biotechnology is too important to get bogged down in weed control.”


Prof. Anthony Trewavas FRS, Emeritus Professor of Cell Biology at the University of Edinburgh, said:

“The WHO classes glyphosate as ‘probably carcinogenic’. Only the cancer agency of the WHO made this claim. The WHO agency on pesticide residues, the US Environment Protection Agency and most importantly the German Federal Institute for Risk Assessment that contains easily the largest toxicological data base on glyphosate, disagree with this designation.

“This latter organisation points out that the WHO cancer committee claims are based on very few documents, mainly on animals and with limited evidence in humans and of course ignore the importance of dose. This same WHO cancer committee also placed hairdressing, art glass, night shifts, tea bag manufacturing and grapefruit juice in the same ‘probably carcinogenic’ class along with emissions from frying food but not those from grilled food.”


Jim Orson, National Institute of Agricultural Botany (NIAB), said:

“Glyphosate was first registered in the US in 1974 and therefore measuring the percent increases in use with 1974 as the base year is bound to come up with a large figure. The increase of tenfold for global use is even more specious because in most of the world it was introduced after 1974 (for instance, the first use in the UK was 1976 according to the UK Chemical Registration Directorate).

“Quoting 2,4-D was in Agent Orange is often erroneously referenced by those who oppose pesticides. The problem with Agent Orange was the contaminants (dioxins) which do not occur in current 2,4-D formulations.

“I have been discussing with colleagues in mainland Europe the IARC decision that it was a possible carcinogen. My understanding is that it is not clear whether IARC took its decision based on formulated glyphosate products or on the active substance. That is an issue that requires clarification before we have a wider debate on hazard versus risk.”


Prof. Johnjoe McFadden, Professor of Molecular Genetics at the University of Surrey, said:

“The authors conflate GMOs with herbicide use.  In many parts of the world use of GMO, particularly pest-resistant (bt) crops have dramatically decreased chemical use and consequent risk of poisoning to farmers.

“All chemicals, including biochemicals, may be dangerous if consumed in large enough doses. Glyphosate (‘Roundup’) is safer than most other herbicides and is biodegradable, which is why farmers, conventional or GM, use it.  Limits should be placed on herbicide levels in food but don’t use it an excuse to attack GMO’s.”


‘GMOs, Herbicides, and Public Health’ by Philip Landrigan and Charles Benbrook published in The New England Journal of Medicine  on Wednesday 19 August. 


Declared interests

Prof. Ottoline Leyser:
Employment and paid consultancies
Director, The Sainsbury Laboratory, University of Cambridge
Company of Biologists, Editor of “Development”
European Research Council, grants board member
Ad hoc payments for one off consultancies for universities and research institutes, funders etc.
Gatsby Foundation, Plant Science Advisor
Norwich Research Park Science Advisory Board
Current Opinion in Plant Biology, Co-Editor in Chief
Biotechnology and Biological Science Council occasional committee work

Other organisations (unpaid)
Umea Plant Science Centre: Advisory Board Member
Gregor Mendel Institute, Vienna: Advisory Board Member
Max Planck Institute for Developmental Biology, Tubingen: Advisory Board Member
European Molecular Biology Organisation: Member
Athena Forum: Chair
Clare College, Cambridge: Fellow
Society of Biology: Fellow and Education
Royal Society: Fellow and Council member, Chair, Science Policy Advisory Group
National Academy of Science, USA: Foreign associate
Leopoldina: Member
International Plant Molecular Biology: President
British Society for Developmental Biology: Chair
Sense About Science: Plant science panel member
Science and Plants for Schools: Grant holder
International Plant Growth Substances Association: Council member
Numerous academic Journals: Advisory Editorial Board member
Science Media Centre: Trustee

Current Research Funding
Gatsby Foundation
European Research Council


Others: None declared

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