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Science  —  10 minutes

Glyphosate in your food

September 21st, 2020
Raymond Lepage, PhD, Doctor in Biochemistry
Raymond Lepage, PhD, Doctor in Biochemistry
Science popularizer

After Vietnam and Austria (2019), then France (2022) and Germany (2023), the list of countries that have decided to ban glyphosate, or at least substantially limit its use, continues to grow. In early September 2019, the City of Montreal was added to this list, pledging to ban the use of glyphosate across its territory by the end of 2019 (a commitment that has since been postponed until the end of 2021).[1] In early July 2020, it was Quebec City’s turn to promise to follow suit “to the extent possible.”[2] In Canada, the use of glyphosate will be allowed until 2030. Here are a few key facts to help you better understand the situation surrounding this herbicide.

What is an herbicide?

An herbicide or weed killer is defined as a product that kills vegetation, in particular weeds. Some herbicides are non-selective, while others are selective.

Herbicides Non-selective herbicide Selective herbicide
Strength Kills all vegetation, whether useful or harmful Kills only “harmful” vegetation, without affecting useful plants
Use In farming, to prepare the soil or assist in harvesting, as well as in forestry and silviculture, where herbicides are used to clear underbrush, help trees grow faster and make harvesting easier. Lawn care and controlling weeds in gardens

There are also simple and natural herbicides, such as table salt and vinegar, for household use in the garden or to get rid of grass growing between the slabs of a patio. However, these harmless herbicides are of little use on large tracts of farmland or woodland.

What is glyphosate?

Glyphosate, better known by its original brand name Roundup, is a non-selective herbicide developed some 40 years ago by the multinational Monsanto (owned since 2016 by the giant Bayer). Found in nearly 200 products sold in Canada, including several dozen for household use (WeedMaster, WipeOut, etc.), glyphosate is the most widely used herbicide in the country.[4]

How does glyphosate work?

Glyphosate prevents the growth of all natural vegetation (as opposed to some genetically modified plants) by blocking an enzyme (protein) involved in synthesizing amino acids essential for the plant’s survival. The plant enzyme affected by glyphosate does not exist in animals or humans. As a result, glyphosate is theoretically of low toxicity to humans, hence its approval in the 1970s in Canada and almost everywhere around the world.

According to Health Canada, glyphosate is currently approved until 2032 for “[…] use on a wide variety of sites including terrestrial feed and food crops, terrestrial non-food, non-feed and fibre crops, and for non-agricultural, industrial and residential weed management for non-food sites, forests and woodlots, outdoor ornamentals and turf.”[3]

Concerns raised by glyphosate

Over the years, the use of glyphosate has increased considerably due to several factors, two of which are very important: the introduction of plants that are genetically modified to resist herbicides, as well as the growing use of glyphosate at harvest time.

Introduction of plants genetically modified to resist herbicides

Because glyphosate kills all plants, useful or harmful, Monsanto has developed genetically modified (GM) seeds to resist the action of its own herbicide. The introduction of transgenic corn, canola and soybeans in the early 1990s led to a revolution in agriculture. In 2018, it is estimated that in Quebec, GM crops accounted for more than 88% of corn, 71% of soybeans and more than 90% of canola, a spectacular increase in less than 30 years![5] Regardless of what governments decide to do about herbicide use on their territories, it will certainly not be easy for farmers to move away from high-yielding GM seeds and glyphosate until other solutions are found which allow them to achieve their goals. France is already promising to ban glyphosate, but only when alternatives have been found.[6] Closer to home, Quebec Premier François Legault, while aware of the potential dangers of glyphosate, intends to “[...] consult with farmers, too, because there’s a question of productivity, of competitiveness with farmers across the border…. So it’s not a simple issue.”[7]

Growing use of glyphosate at harvest time

The other major concern with glyphosate concerns its presence in food. Before the introduction of GM seeds, glyphosate was used mainly to kill weeds in the off-season, between the harvest of one year and the planting of the next year. This meant that in principle, there was minimal contamination of food exposed to glyphosate at harvest time, many months later. However, the introduction of GM seeds encouraged the use of glyphosate throughout the growing season. Glyphosate is now used just before the harvest of GM plants, as well as in a number of other crops, to speed up ripening, dry them out better and make them easier to gather.[8] This practice inevitably increases the levels of glyphosate in our food.

In 2015 and 2016, the Canadian Food Inspection Agency (CFIA) detected traces of glyphosate in about a third of the 3,200 food products it tested.[9] However, according to the agency, only 1.6% of the samples tested contained levels of glyphosate above the maximum allowable limit. But even in this case, they said that the contamination posed no danger to human health.[10]

Why ban glyphosate?

Since 2015, the World Health Organization (WHO) has classified glyphosate in the group of probable carcinogens.[11] It is mainly this recommendation that has prompted or is prompting many countries to ban or significantly limit the use of Bayer-Monsanto’s herbicide.

Another factor that has helped fuel public concern is Monsanto’s ongoing efforts to defend the safety of its flagship product. Questionable practices, including “ghostwriting” (studies carried out by Monsanto and countersigned for a fee by scientists who did not participate in the studies), came to light in two lawsuits filed by American farmers suffering from leukemia, which they blamed on glyphosate. These internal Monsanto documents are referred to as the “Monsanto Papers.”[12]

Is it useful to get tested for urinary glyphosate?

Although the test is available in certain specialized laboratories using mass spectrometry, there are currently no reliable and readily available techniques for testing the general population. In addition, criteria for interpreting the results are not yet available. What level is negligible? What level is suspect? Since there is also no treatment to neutralize or reduce glyphosate levels, the test is currently only useful for individuals who are regularly exposed to concentrated glyphosate, primarily to help them improve their methods to protect themselves.

In the meantime, there is no longer any doubt that, given the extent of its use, a little glyphosate will end up on our plates, and subsequently in our urine. With improved detection techniques, we can expect to find it in a growing number of individuals, even if they scrupulously avoid genetically modified foods.[13]

When in doubt, proceed with caution

Can these traces of glyphosate cause cancer, Parkinson’s disease or other serious illnesses? The answer is far from clear. Until we have a more definitive answer, many countries, municipalities and environmental groups are advocating the sensible precautionary principle. For the general public, this principle would require the agri-food industry to use more products that are recognized as safe. While we wait for a clear verdict on the effects of glyphosate on humans, organic foods are proving to be an attractive solution in the eyes of many.

For the reasons mentioned in the paragraph “Is it useful to get tested for urinary glyphosate?,” Biron does not offer a test for glyphosate.

  1. “Montréal va interdire le glyphosate sur son territoire,” TVA Nouvelles, September 5, 2019, (accessed August 17, 2020).
  2. “La Ville de Québec veut bannir le glyphosate de ses activités,” Radio-Canada, July 5, 2020, (accessed August 17, 2020).
  3. Health Canada, “Re-evaluation Decision RVD2017-01, Glyphosate,” (accessed August 17, 2020).
  4. Carex Canada, “Glyphosate,” (accessed August 17, 2020).
  5. Gouvernement du Québec, “OGM en chiffres,” (accessed August 17, 2020).
  6. “Macron réaffirme que la France interdira le glyphosate « au plus tard dans trois ans,” Le Monde [Paris], November 28, 2017, (accessed August 17, 2020).
  7. “Pesticides et autisme, grave et inquiétant, dit François Legault,” TVA Nouvelles, September 5, 2019, (accessed August 17, 2020).
  8. Glyphosate Renewal Group, “Glyphosate Scientific Dossier Submitted,” (accessed August 17, 2020).
  9. “5 questions sur le glyphosate,” Radio-Canada, October 25, 2017, (accessed August 17, 2020).
  10. Government of Canada, “Safeguarding with Science: Glyphosate Testing in 2015-2016,” (accessed August 17, 2020).
  11. World Health Organization, “IARC Monographs Volume 112: evaluation of five organophosphate insecticides and herbicides,” March 20, 2015, (accessed August 17, 2020).
  12. “Les Montsanto Papers, à la base de la controverse sur le glyphosate,” Le Monde [Paris], August 11, 2018, (accessed August 17, 2020).
  13. “Un pesticide jusque dans votre urine,” La Presse [Montreal], June 17, 2020, (accessed August 17, 2020).
Raymond Lepage, PhD, Doctor in Biochemistry
Raymond Lepage, PhD, Doctor in Biochemistry
Science popularizer
For about 50 years, Raymond Lepage worked as a clinical biochemist in charge of public and private laboratories. An associate clinical professor at the Faculty of Medicine of the Université de Montréal and an associate professor at the Université de Sherbrooke, he has also been a consultant, researcher, legal expert and conference speaker. He has authored or co-authored more than 100 publications for scientific conferences and journals, and now devotes part of his semi-retirement to popularizing science.