Glyphosate, N-(phosphonomethyl) glycine, was introduced in agriculture in 1974 and marketed as a revolutionary solution for weed control. Currently, it is the most widely used herbicide in the world accounting for about 60% of non-selective herbicide sales. Its usage ranges between 600,000 and 750,000 tons annually, with projections suggesting this may increase to nearly a million tons by 2025 (Duke, 2018). Glyphosate’s success skyrocketed with the development of genetically modified (GM) crops that could withstand its effects.
Glyphosate functions by disrupting the shikimic acid pathway, a metabolic route found in plants, fungi, and some microorganisms, but absent in animals. This initially positioned it as a "safe" herbicide. However, its extensive use has sparked growing concerns about potential health risks to humans and the environment.
ENVIRONMENTAL PERSISTANCE
Repeated applications of glyphosate have raised alarms about its potential to contaminate groundwater and accumulate in the environment. Its half-life in soil ranges from 1 to 280 days, depending on factors like soil composition and microbial activity. Its primary metabolite, aminomethylphosphonic acid (AMPA), is even more persistent, with a half-life ranging from 23 to 958 days (Laitinen et al., 2006; Bergström et al., 2011; Bento et al., 2016; Kanisser et al., 2019).
HUMAN HEALTH IMPLICATIONS
Initially deemed safe due to the absence of the shikimic pathway in animals, recent research suggests that chronic exposure to glyphosate have adverse health effects. Its residues have been detected in human and animal urine, with 60–80% of the U.S. population and 44% of Europeans carrying trace amounts (reviewed in Costas-Ferreira et al., 2022). Even low-dose, chronic exposure has raised significant concerns.
Genotoxicity and Cancer Risk. A 2023 study linked lifetime occupational exposure to glyphosate with mosaic loss of chromosome Y (mLOY) (Chang et al., 2023). mLOY is a marker of genotoxicity, which refers to the ability of a substance to damage genetic information within cells. These findings align with the International Agency for Research on Cancer's classification of glyphosate as "probably carcinogenic to humans." (IARC, 2017). However, this conclusion remains disputed by other regulatory agencies, including the European Union and the the Food and Agriculture Organization of the United Nations (FAO) (Tarazona et al., 2017). In addition to glyphosate itself, the adjuvants in commercial formulations, such as polyethoxylated tallow amine, amplify toxicity. These additives enhance the herbicide's penetration into plants but may also facilitate absorption in animals, increasing the potential for adverse effects (Bradberry et al., 2004).
Oxidative Stress and Inflammation. Exposure to glyphosate has been shown associated with increased oxidative stress and inflammatory markers in the body. These physiological changes can have far-reaching consequences for overall health, potentially contributing to the development of various chronic diseases (Sidthilaw et al., 2022).
Impacts on Microbial Communities. Perhaps one of the most overlooked aspects of glyphosate's effects is its impact on microbial communities. These shifts in microbial community composition can have cascading effects. In plants, it may lead to increased susceptibility to pathogens like Fusarium and Rhizoctonia. In animals, it could affect gut health, potentially influencing overall well-being and disease resistance. In humans, alterations in gut microbiota could have implications for various aspects of health, including immunity and metabolism (reviewed in van Bruggen et al., 2021).
Endocrine and Reproductive Health. Glyphosate has also been implicated as an endocrine disruptor, substances that interfere with hormonal systems in the body. Studies have shown that glyphosate can mimic or block natural hormones leading to a reduced sperm quality, altered hormone levels, and potential risks to fetal development during pregnancy (Mendez et al., 2022).
Neurological Impacts. Early-life exposure to glyphosate can disrupt normal cell development by interfering with critical signaling pathways, resulting in impaired differentiation, neuronal growth, and myelination. Glyphosate has also been found to trigger neuroinflammation contributing to nerve cells death. Notably, the doses of glyphosate linked to these neurotoxic effects are significantly lower than the safety thresholds established by regulatory bodies (reviewed in Costas-Ferreira et al., 2022).
Chronic Kidney Disease. Chronic kidney disease (CKD) has been linked to prolonged exposure to pesticides, including glyphosate-based herbicides. In regions where glyphosate use is prevalent, CKD rates are disproportionately high among farming communities. Although multiple factors contribute to CKD risk, glyphosate exposure remains a significant concern (Jayasumana et al., 2014; Gunatilake et al., 2019).
CONCLUSION
While glyphosate remains a widely used herbicide, the potential health risks associated with its use cannot be ignored. As research continues to evolve, it's essential for policymakers, healthcare professionals, and the public to stay informed and engaged in this important issue. To mitigate the risks of glyphosate, individuals can take proactive steps to reduce their exposure in daily life. Key strategies include: (1) prioritizing organic foods and growing your own when possible; (2) using high-quality water filters to remove glyphosate from drinking water; (3) avoiding the use of glyphosate-based herbicides in personal gardening and lawn care; (4) being cautious in public spaces where glyphosate may be used for weed control; (5) thoroughly washing to reduce surface contamination; (6) supporting glyphosate-free initiatives and products and (7) staying informed about local agricultural practices and advocating for stricter regulations.
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