GLYPHOSATE: what does the research actually say?
HERBICIDE & DESICCANT
Glyphosate is a broad-spectrum herbicide used for weed control on fields & lawns and to dry out grain crops before harvest.
FOODS WITH GLYPHOSATE
The most common foods with residue include oats, corn, soybeans, canola, wheat, barley, beans, & lentils.
THE SHIKIMATE PATHWAY
Glyphosate acts by inhibiting an enzyme in the shikimate pathway, preventing the synthesis of amino acids essential for plant growth.
This chemical has been assumed safe for humans because we do not have this metabolic pathway.
However, bacteria do, so glyphosate exposure can cause gut dysbiosis (which DOES have an significant impact on human health).
STATE OF THE RESEARCH
Evidence is not conclusive about the short & long term effects of glyphosate on human & environmental health.
Some studies find it perfectly safe and others the opposite.
Notably, much of the research is funded by industries with interest in certain study outcomes—on both sides of the issue.
in vitro: DNA damage, estrogen interference, increased oxidative stress, nutrient binding, inflammation, cancer, etc
in vivo: impact on cardiovascular system, intestinal permeability, celiac disease, dysbiosis, nervous system development & function, fertility & reproduction, autism, etc
epidemiological: few effects overall, increased risk for non-Hodgkin’s lymphomas in exposed farmers
AMINO ACID ANALOGUE
Glyphosate has a similar chemical structure to glycine.
If mistakenly substituted in polypeptide chains, it can distort or inactivate essential proteins & enzymes.
CULPRIT OR SIDEKICK?
Although glyphosate is often the active ingredient in mixed herbicides, some hypothesize that added surfactants are more problematic.
Hence, glyphosate-based herbicides (GBHs) are found more toxic than plain glyphosate.
EXPERT DISAGREEMENT
To add confusion, 2 regulatory boards make opposite statements about glyphosate safety:
IARC: “probably carcinogenic to humans”
(considered plain glyphosate & GBHs, included in vitro & in vivo but few epidemiological studies)
EFSA: “unlikely to represent a carcinogenic hazard for humans”
(considered plain glyphosate only, included human epidemiological studies only)
WHAT LEVEL IS SAFE?
This question is as philosophical as scientific (and very controversial).
Currently, if food residue tests below “accepted levels”, it is considered safe.
However, long-term exposure to very low levels has technically never been studied.
OTHER CONSIDERATIONS
Beyond human health, there are concerns about glyphosate build-up in soil & water, wildlife impacts, and herbicide-resistant weeds.
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References
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Costas-Ferreira, C., Durán, R., & Faro, L. R. F. (2022). Toxic Effects of Glyphosate on the Nervous System: A Systematic Review. International journal of molecular sciences, 23(9), 4605. https://doi.org/10.3390/ijms23094605
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National Pesticide Information Center Glyphosate General Fact Sheet. [(accessed on 27 September 2023)]. Available online: http://npic.orst.edu/factsheets/glyphogen.html
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