Mammalian toxicity of herbicides used in intensive GM crop farming

Abstract The toxicity of major herbicides on mammalian physiology is reviewed, with a focus on herbicides associated with agricultural systems employing genetically modified crops: glyphosate, 2,4-D, dicamba, glufosinate, quizalofop, sulfonylurea, imidazolinones, mesotrione, and isoxaflutole. Other products used in intensive agriculture worldwide are discussed: paraquat, atrazine, metolachlor, acetochlor, and alachlor. The frequent withdrawal of toxic ingredients creates the impression that herbicides are increasingly safe, but also implies that their initial assessment was insufficient. We highlight knowledge and technical gaps in the determination of safety thresholds: long-term effects of herbicides and their combinations at environmental levels (i.e., real-life exposure scenarios), epigenetics effects, and impacts on the gut microbiome are insufficiently tested. Most of the studies are focused on a few usual suspects (glyphosate, 2,4-D, atrazine), and the toxicology of some major herbicides remains underexplored. This amplifies the inescapable gap between the introduction of a new herbicide and the detection of its health effects.