Glyphosate: is it that bad?- A blog by Felipe Becerra Sanchez
What is it?
Glyphosate is a non-selective herbicide that inhibits an enzyme involved in three amino acids biosynthesis (phenylalanine, tyrosine and tryptophan). Glyphosate is mainly absorbed through the leaves, and then internally distributed to rest of the plant. The enzyme inhibition causes a diversion in the energy from other processes, and after few a days the plant turns yellow and dies.
Why it is so popular?
Glyphosate can be used as a non-selective herbicide, and also can be used in the cultivation of glyphosate-resistant plants. The first glyphosate-resistant crops were soybeans and corn, two of the most important worldwide crops. The development of these glyphosate-resistant plants allowed the application of glyphosate to control weeds without killing the crop plant.
What was used before glyphosate?
Paraquat and diquat are two chemicals used for the same purpose as glyphosate. These compounds kill the plant tissue on contact by the production of superoxide anions. Both of them are toxic for animals and they have been associated with the development of Parkinson disease. Paraquat is banned in the European Union.
Another example of herbicide is Atrazine. It is the second most used pesticide in the US. Although its herbicide activity is inhibiting a protein involved in the photosynthesis, no present in animals, it has shown to be toxic for animals. The finding of atrazine in groundwater led to its prohibition in the European Union.
How toxic is glyphosate?
Despite the International Agency for Research on Cancer classifying glyphosate as ‘probably carcinogenic for humans’, the European Food Safety Authority, the FAO and the WHO have published several reports classifying it as ‘substance that is unlikely to be carcinogenic’, and that the daily intake if any, would be too low to cause any carcinogenic effect.
A study published by Seralini in 2012 became viral because it showed pictures of rats fed with GMO corn and glyphosate in the drinking water that developed tumours. Besides, feeding rats with glyphosate in its drinking water, the measurements and statistics were far from meeting scientific procedures, and the rats were susceptible to develop tumours when the food intake was not restricted. This article was retracted one year after its publication but not before causing a full media coverage and damaging the perception of glyphosate by the general public.
Torretta et al. (2018) published a review on glyphosate environmental and human toxicity, in which they concluded; ‘Despite numerous studies regarding the dangers resulting from the extensive use of glyphosate, it is NOT possible to attribute a clear and unambiguous definition to glyphosate, especially regarding its potentially harmful effects on humans.’
Herbicides, like pesticides, or even medicines are chemicals that interfere with the ‘normal’ metabolism of plants, insects or humans. In all the cases it is absolutely indispensable the appropriate use of them. The risk of glyphosate is not in its use, it is the carelessly handling that can lead to high exposures, groundwater contamination etc.
Glyphosate might be the most used herbicide, but at expenses of other herbicides that have higher toxicities and entail higher environmental risks. The future of herbicides should be better education, regulation of its application, and research in new and more environmentally friendly compounds.