Roundup causing cancer?

20 Apr 2015

In late March, the International Agency for Research on Cancer (IARC) announced that glyphosate would be added to its list of agents that are “probably carcinogenic to humans”. The IARC is an agency within the World Health Organization so the announcement has been widely reported. This news has delighted those who oppose GM technology and/or pesticides. There are many “we told you so” articles on their websites and in the popular press. 

Does glyphosate really cause cancer? I am no expert on this issue but have been looking at the comments made by UK scientists ( and also, I have read an excellent blog which carefully weighs up the evidence used by the IARC when coming to its preliminary conclusion ( Interestingly, the latter quotes a huge American study which shows that farm workers are less likely to get the cancer in question (non-Hodgkin lymphoma) than the general population.

The IARC admits that it is working from a very limited database of studies on the subject. This reminds me of the Daily Mail type of article where one quoted study suggests that there is evidence that a particular food type causes cancer and yet within a few weeks there is another study that concludes the opposite.  The following diagram really puts such studies into context. The blobs are the average result for an individual study but the inevitable error in each study often means that a blob on the right or left hand side of the vertical line may not be significantly different to the line. According to the blog to which I referred, this is the case for the few studies on glyphosate and non-Hodgkin lymphoma. 

There are two reasons for me potentially to panic over the IARC announcement. One is that I have handled glyphosate over the last forty years or so and also, if it is true, then there could be implications for the availability of the herbicide. However, I am not even concerned after reading the comments on the evidence.

It is worth mentioning that the IACR list of known carcinogens includes alcoholic beverages, emissions from coal fires, untreated or mildly treated mineral oils, outdoor air pollution, solar radiation, soot, wood dust and smoking tobacco. I suggest that it is worth paying more attention to our exposure to these than the so-called ‘probable’ risk from glyphosate but please remember that pesticides should always be handled with care.

After researching the issue, I am also a lot more reassured about my coffee addiction (see the diagram).  In fact, I was once so concerned about my intake that I asked my GP if it was possible to drink too much coffee. He thoughtfully put down his cup of coffee and said “I hope not”. The diagram is also a comfort to those, like me, who love a glass of wine. A couple of years ago I heard a talk by an eminent scientist at the University of East Anglia who concluded that a healthy diet could be based on red wine and chocolate. Now where are those Easter eggs I have to finish eating? For health reasons you understand.