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expert reaction to EFSA’s conclusions on glyphosate safety

The European Food Safety Authority has published its reassessment of the safety of glyphosate, a component of herbicides. The report concludes that glyphosate is unlikely to cause cancer in humans.


Dr Peter Jenkinson, Genotoxicologist and MD of CEHTRA France & UK, said:

“The EFSA conclusion on the genotoxic and carcinogenic risk assessment of the active substance glyphosate, and the contradictory conclusion they achieved in comparison to that of IARC, highlights the importance of the assessment process used in each case.

“The EFSA assessment was focussed on the active substance glyphosate itself, rather than on formulations that include glyphosate and other co-formulants. Those other co-formulants may have produced confounding results in some cases and their relevance to the glyphosate products on sale in Europe is unclear.

“Furthermore, EFSA included in their assessment additional studies or data that were not assessed by IARC, which may have contributed to the contrary conclusion.

“But critically, EFSA followed a weight of evidence approach whereas IARC took the view that if one study showed a positive result then it took precedence over negative studies, even though there may be many more negative than positive studies.  In fact, IARC also took the opportunity to analyse the results of some studies using statistical methods not defined by the study authors in their protocol; this approach may be considered to be unjustified. In this way they may have identified studies as positive when in fact the study authors considered them to be negative.

“So, whilst at face value the opinions of IARC and EFSA appear to be contrary, the reality is that they are not directly comparable. The database that the two groups considered were not identical and the methods used to draw their conclusions were different.

“Which conclusion or opinion is ‘correct’ depends on your point of view on the methods used by the two agencies. For me, the EFSA methodology is the one that is more scientific, pragmatic and balanced.”


Prof. David Coggon, Professor of Occupational and Environmental Medicine at the University of Southampton, said:

“When comparing the different conclusions arrived at by IARC in March 2015 and now EFSA, it is important to bear in mind that EFSA and IARC operate within different frameworks.

“IARC is about the assessment of cancer hazard – i.e. the likelihood that a chemical might, at least in some circumstances, cause cancer in humans. EFSA is concerned principally with whether there is sufficient confidence that a pesticide, when used according to the conditions of its approval, will not pose an unacceptable risk to human health or the environment.

“The level of precaution that is applied in the face of scientific uncertainty depends on value judgements, and is not a scientific question (although scientists try to assess levels of uncertainty and communicate them to risk managers). I suspect that what EFSA will have looked at is whether, given the levels of precaution that are currently applied in the regulation of pesticides more generally, the uncertainties about possible risks of cancer from glyphosate are sufficient to warrant regulatory restrictions.”




All our previous output on this subject can be seen at this weblink:


Declared interests

Dr Peter Jenkinson: “I am an expert genotoxicologist that is employed by a consultancy company that works for companies in the chemical industry including the plant protection product industry. However, my main focus is on industrial chemicals, not agrochemicals; and I have no commercial interest in glyphosate or glyphosate products.”

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