Understanding Glyphosate: Its Uses, Concerns, and Global Impact
What is Glyphosate?
Glyphosate is an organophosphorus compound - specifically a phosphonate - commonly utilized as a broad-spectrum herbicide for the purpose of killing undesired vegetation (i.e., weeds) in agricultural, public, and home garden settings. It achieves this purpose by competitively inhibiting plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP), which is an enzyme chiefly produced by plants and microorganisms and forms a crucial component in the biosynthesis of folates and aromatic amino acids – without which, plant growth, development, and survival are not possible1.
Significantly, this particular metabolic pathway is absent in animals, making it a unique feature of plant and microbial biology2. Thus, given its broad-spectrum effectiveness and selective action, Glyphosate proved to be an attractive means of invasive weed control. As such, upon being first introduced into the market more than 40 years ago, under the trade name ‘Roundup’, Glyphosate containing herbicides have been adopted for use in wide range of agricultural settings3.
Notably, this adoption was further encouraged by the introduction of ‘Roundup Ready’ crops, which are plant lines genetically modified to resist Glyphosate’s inhibitory action, thereby enabling farmers to eradicate weeds without threatening the health of their crops.
Since the time it was introduced, Glyphosate containing herbicides have become ubiquitous within the agricultural sectors, and are now manufactured by at least several dozen chemical companies worldwide. To this point, there are approximately 500 unique Glyphosate containing products registered for use in Australia, from residential gardens through to commercial farming operations4. Between 1994 and 2014, more than 9.5 million tonnes of Glyphosate were applied to crops, globally5. Notably, in 2007 twice as much Glyphosate was used in the United States as the next most heavily applied pesticide – Atrazine.
Why the Concern?
Though touted as being a ‘less toxic’ than the alternatives that pre-dated it, the human health and environmental implications of Glyphosate use has since become a matter of significant public concern, particularly following a report published in 2015 by the International Agency for Research on Cancer (IARC), a branch of the World Health Organization (WHO) 1,3.
This report, also known as IARC Monograph 112 (available on IARC’s website), evaluated the carcinogenicity of a number of organophosphate insecticides and herbicides, including Glyphosate6. Following a review of more than 1000 studies, performed by a series of independent experts free from vested interests (i.e., financial conflicts), IARC classified Glyphosate as “probably carcinogenic to humans” (Group 2A).
This conclusion was based on a finding of “limited” evidence of cancer in humans (derived from real-world exposure data) and “sufficient” evidence of cancer in experimental animal studies utilizing pure Glyphosate (i.e., 100 % concentration). For an overview of the IARC classification of substances and their associated level(s) of evidence, please see Table 1 below.
In addition to being deemed “probably carcinogenic to human”, IARC also concluded that there was “strong” evidence for genotoxicity, both for pure Glyphosate and for Glyphosate containing formulations.
Why the Controversy?
As can be surmised from the news media’s coverage of Glyphosate in recent years, these findings have generated substantial debate within the public health and safety space. Contributing to this controversial debate are the findings of a recent public health investigation, performed by the Centre for Disease Control and Prevention (CDC), which detected traces amounts of Glyphosate in more than 80 % of urine samples drawn from both children and adults residing in the United States7.
This finding thus raised concerns about the pervasiveness and persistence of Glyphosate in the environment - particularly its potential to accumulate in eco-systems and/or enter the food chain. Notably, one factor contributing to the pernicious ubiquity of Glyphosate is its half-life in various environmental settings, which directly influences its continued presence in soil, water, and air. Such persistence allows Glyphosate to remain active long enough to influence agricultural processes, but also heightens the risk of runoff into waterways and leaching into groundwater, further amplifying human exposure. In soil-based environments, for example, the half-life of Glyphosate ranges between 2 and 197 days, with a typical field half-life of 47 days8.
This environmental persistence, combined with its extensive use, has thus created the potential for widespread, chronic low-level exposures to Glyphosate, particularly through the ingestion of contaminated water or food sources. Concerningly, these findings thereby suggest that Glyphosate exposure is not only commonplace within modern society but may also be entirely unavoidable for large segments of the population.
Given the significant public health implications of such widespread, chronic low-level exposure to Glyphosate, experts and public health advocates have called for immediate measures to mitigate risks. However, this call-to-action has yet to be heeded, as there remains disagreement within both the scientific and regulatory communities regarding the risk(s) associated with Glyphosate exposure9.
Unfortunately, at the time of writing, there exists no consensus within the international scientific community as to the carcinogenic potential of Glyphosate containing products, which diminishes the justification of any large-scale mitigative action. Most notably, many governmental health authorities – including Australia’s own independent regulator, the Australian Pesticides and Veterinary Medicines Authority (APVMA) – have expressed a significant degree of scepticism with respect to IARC’s findings, relying instead on their own weight-of-evidence evaluations when determining the safety and regulatory status of Glyphosate4.
The APVMA, alongside international regulatory agencies such as the United States’ Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA), maintains that there is currently no compelling evidence to suggest that Glyphosate poses a carcinogenic risk to humans when as directed by the respective product’s label instructions4,10,11. These organizations argue that IARC's classification of Glyphosate as being "probably carcinogenic to humans" (Group 2A) does not align with the broader body of research, particularly studies examining real-world, lower-dose exposure. In fact, regulators often point out that IARC’s classification criteria are hazard-based, meaning that they assess the degree of potential risk under any exposure scenario, whilst agencies like APVMA conduct risk-based assessments which consider actual levels of exposure4,6.
This difference in approach is a key factor contributing to the ongoing discrepancy in global regulatory stances. However, it is critical to acknowledged that many international regulatory agencies rely predominantly upon industry derived data which are not made publicly available, which complicates efforts to independently validate these findings and fosters scepticism among public health advocates and environmental groups6. Critics argue that reliance on industry-funded research introduces potential bias, as these studies are often conducted or commissioned by the very companies that manufacture Glyphosate-containing products12.
This lack of transparency raises questions about the robustness of regulatory evaluations and whether they adequately address long-term, low-dose exposure risks or the potential synergistic effects of Glyphosate with other chemical formulations present in herbicide products.
Given the divergence between hazard-based and risk-based assessment methodologies, alongside concerns pertaining to data transparency, there is a growing consensus that independent, peer-reviewed research will be necessary to bridge these gaps9. Studies focusing on real-world exposure scenarios, as well as the cumulative effects of chronic, low-level exposure to Glyphosate and its formulations, are particularly crucial. Such efforts might facilitate greater alignment between regulatory agencies, reduce public confusion, and provide clearer guidance on the responsible use of Glyphosate. Until these discrepancies are resolved, public trust in regulatory agencies may remain tenuous, particularly as legal and scientific disputes over Glyphosate continue to unfold.
Moving Forward: Striking a Balance.
Until definitive answers emerge, the debate over Glyphosate will likely persist, reflecting broader tensions between advancing agricultural productivity and safeguarding human and environmental health. Unfortunately, attempts to facilitate the adoption of “safer” alternatives to Glyphosate have proven unsuccessful, largely due to a combination of economic, logistical, and practical barriers13. For instance, many proposed alternatives are associated with higher costs, limited efficacy across a wide spectrum of weed species, and/or greater environmental persistence.
Additionally, transitioning away from Glyphosate invariably necessitates significant changes in farming practices, which may be time-consuming and financially burdensome for farmers, particularly in regions where Glyphosate-resistant crops dominate agricultural systems. Moreover, finding a “safer” alternative herbicide may prove more challenging that one would expect, as diquat-, fluazifop-, and triclopyr-based herbicides also present a number of human health and environmental concerns, for example14,15,16.
As such, until such time that the scientific and regulatory communities reach a consensus on the long-term effect of Glyphosate exposure, the debate will continue to be shaped by both public perception and evolving scientific evidence. In the interim, it is important that end-users be made aware of the potential risks associated with Glyphosate use, as well as the steps they can take to mitigate exposure. This includes following label instructions carefully, utilizing personal protective equipment wherever recommended, and the employ of integrated pest management practices that reduce dependency on chemical herbicides.
As the global community continues to debate the safety of Glyphosate, it is imperative to keep the focus on finding solutions that not only protect public health but also support the economic needs of the agricultural industry. The long-term goal should be to achieve a harmonious balance between agricultural innovation, environmental sustainability, and public health protection, ensuring that future generations inherit a healthier and more resilient food system. The role of farmers and agricultural stakeholders cannot be overlooked in this conversation.
They are often on the front lines, balancing the pressures of maintaining crop yields with the responsibility of ensuring food safety and environmental sustainability. Providing these stakeholders with more effective tools for managing weeds, including alternative herbicides, organic practices, and new technologies, will be vital in moving forward.
Moving Forward: How Can ChemAlert Help?
ChemAlert is a robust chemical management system which can play a critical role in addressing concerns surrounding the use of Glyphosate and other chemicals in agricultural settings. By providing comprehensive information on the chemical properties, potential hazards, and regulatory requirements associated with Glyphosate, ChemAlert helps users make informed decisions about its use and mitigation strategies.
ChemAlert offers detailed safety data sheets (SDS) for Glyphosate, outlining potential health risks, recommended safety measures, and first aid procedures. This ensures that users have immediate access to accurate safety information, helping reduce the risk of exposure. In addition, through ChemAlert's tracking and monitoring tools (i.e., Stock Register), users can assess potential exposure levels to Glyphosate across different occupational environments, including agricultural fields, storage facilities, and food processing areas. This can help identify areas of concern and implement corrective actions before risks become significant.
By utilizing the resources provided by ChemAlert, agricultural stakeholders, including farmers, chemical suppliers, and regulatory agencies, can take proactive steps to mitigate potential risks associated with Glyphosate use.
References
1 Kavita Gandhi, Shaila Khan, Mansi Patrikar, Aishwarya Markad, Niraj Kumar, Aaditee Choudhari, Pallavi Sagar, Shreya Indurkar. (2021) Exposure risk and environmental impacts of glyphosate: Highlights on the toxicity of herbicide co-formulants, Environmental Challenges, Volume 4. Source
2 Herrmann, K. M.; Weaver, L. M. (1999). "The Shikimate Pathway". Annual Review of Plant Physiology and Plant Molecular Biology. 50: 473–503. Source
3 Duke, S.O. and Powles, S.B. (2008), Glyphosate: a once-in-a-century herbicide. Pest. Manag. Sci., 64: 319-325. Source
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9 Connolly A, Koch HM. Invited Perspective: The Continuing Debate-Is Glyphosate a Problem, and Can an Organic Diet Protect Us from Exposures? Environ Health Perspect. 2023 Jul;131(7):71304. doi: 10.1289/EHP13053. Epub 2023 Jul 26. PMID: 37493358; PMCID: PMC10370339.
10 epa.gov
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15 Ore A, Olayinka ET. Fluazifop- p-butyl, an aryloxyphenoxypropionate herbicide, diminishes renal and hepatic functions and triggers testicular oxidative stress in orally exposed rats. Toxicol Ind Health. 2017 May;33(5):406-415. doi: 10.1177/0748233716657763. Epub 2016 Jul 4. PMID: 27378613.
16 Michael Bartels, Colin Brown, Git Chung, Melissa Chan, Claire Terry, Sean Gehen, Marco Corvaro. Review of the pharmacokinetics and metabolism of triclopyr herbicide in mammals: Impact on safety assessments. Regulatory Toxicology and Pharmacology, Volume 116, 2020, 104714, ISSN 0273-2300. Source
