A recent scientific review claims the weed killer glyphosate raises the risk of developing the cancer non-Hodgkin lymphoma by 41 percent. But deciding what causes cancer can be complicated and there are lots of people and organisations on different sides arguing for against this. So in this edition of More or Less, we look at the disagreements and how the authors of the review came up with the results. With cancer epidemiologist Dr Geoffrey Kabat, Toxicologist Dr Luoping Zhang and statistician Sir David Spiegelhalter. Producer: Darin Graham Presenter: Charlotte McDonald Editor: Richard Vadon