Glyphosate Herbicide: A Risky Public Health Concern. Glyphosate is an herbicide commonly used by farmers, consumers, and local parks alike. It is the main ingredient in Roundup, made by the biotech company Monsanto (who also is the highest producer of genetically modified seeds). Glyphosate is the most heavily sprayed herbicide in the world.

Introduced in the 1970s as a “safer” pesticide option, glyphosate is applied to kill weeds as well as help to ripen certain crops. It is non-selective, meaning it will kill most plants. Glyphosate works by interfering with an enzyme pathway called the shikimic acid pathway. Humans do not have this enzyme; however, our gut bacteria do.

Glyphosate: A Public Health Concern

Glyphosate is an herbicide commonly used by farmers, consumers, and local parks alike. It is the main ingredient in Roundup, made by the biotech company Monsanto (who also is the highest producer of genetically modified seeds). Glyphosate is the most heavily sprayed herbicide in the world.

Introduced in the 1970s as a “safer” pesticide option, glyphosate is applied to kill weeds as well as help to ripen certain crops. It is non-selective, meaning it will kill most plants. Glyphosate works by interfering with an enzyme pathway called the shikimic acid pathway^[1]. Humans do not have this enzyme, however, our gut bacteria do.

When glyphosate was first introduced to farmers, it was mainly used prior to planting a field or for weed control in areas that were not used for growing crops. Initial safety testing for toxicity was limited. While a review of safety published in 2000 stated that glyphosate was safe^[2], more recent papers suggest that the interpretation of safety needs to be reevaluated^[3] and that Monsanto may have interfered with some of the research^[4]. Most of these studies also examined glyphosate alone, and not in combination with other toxic ingredients found in herbicides like Roundup.

The statement by the World Health Organization concluding that glyphosate is “probably carcinogenic to humans” would seem to be the catalyst to minimize use, but unfortunately, that is not the case. The use of glyphosate has grown exponentially since it was first introduced – nearly 100 times more since the seventies^[5]. Not only is the herbicide being used more often by farmers, but also in higher amounts. As a result of the emergence of glyphosate-resistant weeds, farmers are forced to use more herbicide in combination with other pesticides to achieve the same results^[6].

Numbers have also increased with the introduction of “Roundup Ready” GMO glyphosate-tolerant crops^[7]. This begins a vicious cycle where genetically engineered crops are increasing, and as a result, more glyphosate is used. More than half of the total volume of glyphosate used in the U.S. from 1974 to 2014 was sprayed in the last ten years^[8].

Where are you exposed to glyphosate?

Potential exposure to glyphosate herbicide goes beyond those who are directly spraying the herbicide. Glyphosate has been found in water and soil, potentially contaminating communities in neighboring agricultural regions^[9]. Many community areas also use Roundup to control weeds in areas heavily used by people for leisure activities like parks and town squares.

A consensus statement published by Scientists in 2016 called for additional research to examine safety data in terms of daily intake, stating current estimates are based on outdated science^[10]. The scientists indicate that the use of glyphosate closer to harvest has also increased, further increasing exposure to the herbicide in our food. Farmers in damp climates may spray close to harvest to help dry the crop more quickly^[11].

In our food system, glyphosate is found in nearly all the global soybean supply. Glyphosate is used on many crops, especially maize, soy, canola, wheat, barley, oats, and edible beans. The U.S. Department of Agriculture tested soybeans for glyphosate residues in 2011 and found reside in 90% of all samples^[12].

The concern goes beyond the crop itself but expands to many processed foods. The Environmental Working Group (EWG) conducted a study to examine the presence of glyphosate residue in non-organic oat-based breakfast cereals and foods marketed to children. The report found glyphosate in every single tested product (28 different samples), and all but two were at higher levels than the EWG has concluded as safe^[13]. More recently, the EWG conducted another independent test examining wheat-based products, including pasta and wheat-based cereals. The testing again found glyphosate residue in all the products, although the cereals were in smaller amounts suggesting the potential of cross-contamination^[14].

Interestingly, the FDA only recently began testing food for glyphosate residue, and in 2016 released data that found the herbicide in two-thirds of corn and soybean samples, along with many other crops^[15].

As glyphosate is used to control weed growth in vineyards, CALPIRG conducted a test on twenty popular beer and wine samples to assess for glyphosate residue. Consumers are assured that this is a safe practice because the herbicides are not sprayed on the grapes themselves, but instead on the weeds. CALPIRG found glyphosate residue in 19 of the 20 samples of beer and wine, suggesting that glyphosate is likely to be much more widespread in our food and drink supply than imagined^[16].

What are the health risks and controversies of glyphosate herbicide exposure?

As glyphosate is widespread in our food supply, it is essential to understand the impact of potential exposure. While Monsanto and other agriculture corporations will assert that there is no evidence that glyphosate is unsafe for humans, it is now becoming more apparent that this is not the case.

Glyphosate is toxic to human cells, even more so than other herbicides^[17].

Farmworkers and those living and working in agricultural communities are most at risk, but all consumers should be concerned now that it is rampant in our food supply. One study found glyphosate residues in the blood and urine of farmworkers, making it clear that direct contact leads to measurable levels in the body^[18]. Another study examining adults in Southern California found levels of glyphosate in the body have increased over 1000% in the last 20 years^[19].

There have been many studies examining potential adverse health outcomes associated with the use of glyphosate and Roundup. Some are association studies in humans, while others are animal studies.

Cancer

As previously mentioned, the WHO has classified glyphosate as “probably carcinogenic to humans”^[20]. There have been several well-publicized lawsuits against Monsanto for the role Roundup has played in the development of cancer. In 2019 a jury awarded $80 million in damages to a man who claimed Roundup caused his cancer, opening the door for hundreds of other lawsuits against Roundup. The man in the case was diagnosed with Non-Hodgkins lymphoma (NHL), a type of cancer that has been examined concerning increasing numbers in farmworkers^[21]. As NHL cases doubled in the U.S. between 1975 and 2006, the association with glyphosate needs more research. One study also suggested that there may be an increase in multiple myeloma with glyphosate exposure, but more research is necessary to examine further^[22].

Organ damage

Several studies on rats found kidney and liver changes with elevated liver enzymes in relation to glyphosate^[23]. There is also a significant observational association between chronic kidney disease and male agricultural workers in areas with heavy glyphosate usage in combination with hard water^[24].

Gut dysbiosis and celiac disease.

While humans and animals don’t contain the enzyme that glyphosate targets from the shikimic pathway, the microbes in our body do. The attack on this enzyme may be how glyphosate negatively affects our gut bacteria. Dysbiosis, or an imbalance of the healthy bacteria in the human gut, has been associated with glyphosate^[25]. Glyphosate may change the bacteria in the gut, encouraging “bad” bacteria that may be pathogenic in increased numbers while reducing healthy bacteria.

Disruption in the microbiome is also seen in honey bees, where exposure to glyphosate can disrupt the healthy gut bacteria leading to potential health issues^[26]. Given recent concerns in decreases in the population of honeybees, and the critical role they play as pollinators for the environment, scientists are examining this more carefully.

A recent paper also examined the association between the rise of celiac disease and the use of glyphosate.

The authors argue that many of the known complications of celiac disease, such as the increased risk of NHL and impairments in detoxification enzymes, are known associations with glyphosate use^[27].  Additionally, alterations and dysbiosis are associated with the development of celiac.

• Neurological diseases.While more research is needed, the same authors who wrote the paper on the relationship between celiac disease and glyphosate wrote an additional paper citing an association between glyphosate and neurological conditions such as Alzheimer’s and Parkinson’s^[28]. While the paper suggests multiple pathways in this connection, the underlying suggestion is that glyphosate depletes manganese in the body (as seen in a study with cow’s fed Roundup Ready feed). Manganese is a protective nutrient against free radical damage in the cells. The authors suggest that the lack of manganese can lead to the oxidative damage of mitochondria, the energy producers in our cell. Mitochondrial damage is a characteristic of autism and Alzheimer’s.

• Congenital malformations and hormone disruption.

  Pigs fed glyphosate contaminated soybeans have had increases in congenital malformations^[29], while birth defects have been noted people living near agricultural areas using glyphosate-tolerant crops^[30]. Pregnant rats exposed to glyphosate resulted in reproductive development impairment in baby rats^[31]. Additional studies have shown potential endocrine disruption, with developing babies and children most at risk. The difficulty in studying the hormone disruption is that effects are not always known right away because exposure early in life can lead to health issues later in life.

What is the current status of glyphosate in the U.S.?

Human exposure to glyphosate is not well understood despite the significant increase in use worldwide.  Only recently has food been tested by the FDA. Further, the impact of glyphosate, in combination with GMOs or in products like Roundup, which uses glyphosate in conjunction with other chemicals, could potentially increase the toxic burden.

Scientists and consumers are calling for increases in independent testing outside of the biotech companies to better understand the impact on human health. Small numbers of towns and communities are developing independent bans on the use of synthetic pesticides like Roundup in community areas, but more oversight is necessary to protect everyone^[32].

How to avoid glyphosate herbicide exposure?

The best way to avoid glyphosate herbicide is to eat certified organic food^[33], even better if the produce is grown locally and found at a farmer’s market where you can have a conversation with the farmer. Some small farmers may not be able to afford the organic certification but will still avoid using glyphosate.

You can also get involved with your local leaders to promote bans on the use of synthetic pesticides like Roundup in your local parks and recreation areas. Choose alternative non-toxic products for your own yard as well.

The science is compelling enough to avoid glyphosate, even in small amounts.

Given Bayer, the owner of Monsanto has more than 42,000 lawsuits in progress^[34], we can expect more information to come to the surface. In the meantime, it makes sense to protect yourself from exposure of the chemical by choosing organic foods and non-toxic gardening supplies.

References:

^[1] “Glyphosate General Fact Sheet.” Accessed May 5, 2020. http://npic.orst.edu/factsheets/glyphogen.html#whatis.

^[2] Williams, G. M., R. Kroes, and I. C. Munro. “Safety Evaluation and Risk Assessment of the Herbicide Roundup and Its Active Ingredient, Glyphosate, for Humans.” Regulatory Toxicology and Pharmacology: RTP 31, no. 2 Pt 1 (April 2000): 117–65. https://doi.org/10.1006/rtph.1999.1371.

^[3] Mesnage, R., N. Defarge, J. Spiroux de Vendômois, and G. E. Séralini. “Potential Toxic Effects of Glyphosate and Its Commercial Formulations below Regulatory Limits.” Food and Chemical Toxicology: An International Journal Published for the British Industrial Biological Research Association 84 (October 2015): 133–53. https://doi.org/10.1016/j.fct.2015.08.012.

^[4] “Monsanto’s Role in Roundup Safety Study Is Corrected by Journal – Bloomberg.” Accessed May 5, 2020. https://www.bloomberg.com/news/articles/2018-09-27/monsanto-s-role-in-roundup-safety-study-is-corrected-by-journal.

^[5] Myers, John Peterson, Michael N. Antoniou, Bruce Blumberg, Lynn Carroll, Theo Colborn, Lorne G. Everett, Michael Hansen, et al. “Concerns over Use of Glyphosate-Based Herbicides and Risks Associated with Exposures: A Consensus Statement.” Environmental Health 15 (February 17, 2016). https://doi.org/10.1186/s12940-016-0117-0.

^[6] “Trends in Glyphosate Herbicide Use in the United States and Globally | SpringerLink.” Accessed May 5, 2020. https://link.springer.com/article/10.1186/s12302-016-0070-0.

^[7] “Glyphosate-Resistant Crops: Adoption, Use and Future Considerations – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/18078304/.

^[8] “Trends in Glyphosate Herbicide Use in the United States and Globally | Environmental Sciences Europe | Full Text.” Accessed May 5, 2020. https://enveurope.springeropen.com/articles/10.1186/s12302-016-0070-0.

^[9] Myers, John Peterson, Michael N. Antoniou, Bruce Blumberg, Lynn Carroll, Theo Colborn, Lorne G. Everett, Michael Hansen, et al. “Concerns over Use of Glyphosate-Based Herbicides and Risks Associated with Exposures: A Consensus Statement.” Environmental Health 15 (February 17, 2016). https://doi.org/10.1186/s12940-016-0117-0.

^[10] IBID

^[11] IBID

^[12] “Trends in Glyphosate Herbicide Use in the United States and Globally | Environmental Sciences Europe | Full Text.” Accessed May 5, 2020. https://enveurope.springeropen.com/articles/10.1186/s12302-016-0070-0.

^[13] “Roundup for Breakfast, Part 2: In New Tests, Weed Killer Found in All Kids’ Cereals Sampled | EWG.” Accessed May 5, 2020. https://www.ewg.org/release/roundup-breakfast-part-2-new-tests-weed-killer-found-all-kids-cereals-sampled?utm_source=search&utm_medium=ads&utm_campaign=glyphosateincereal&gclid=CjwKCAiAhc7yBRAdEiwAplGxX8dKzk1wIJ-jv9Uw21wPoRt2h-nhPpaP-GBvvCrkTEsJntMNfSSh_RoCJSMQAvD_BwE.

^[14] “Glyphosate Contamination in Food Goes Far Beyond Oat Products | EWG.” Accessed May 5, 2020. https://www.ewg.org/news-and-analysis/2019/02/glyphosate-contamination-food-goes-far-beyond-oat-products.

^[15] Nutrition, Center for Food Safety and Applied. “Questions and Answers on Glyphosate.” FDA, March 30, 2020. https://www.fda.gov/food/pesticides/questions-and-answers-glyphosate.

^[16] “Glyphosate Pesticide in Beer and Wine | CALPIRG.” Accessed May 5, 2020. https://calpirg.org/feature/cap/glyphosate-pesticide-beer-and-wine.

^[17] Mesnage, Robin, Nicolas Defarge, Joël Spiroux de Vendômois, and Gilles-Eric Séralini. “Major Pesticides Are More Toxic to Human Cells than Their Declared Active Principles.” BioMed Research International 2014 (2014): 179691. https://doi.org/10.1155/2014/179691.

^[18] “Glyphosate Biomonitoring for Farmers and Their Families: Results From the Farm Family Exposure Study – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/14998747/.

^[19] “Excretion of the Herbicide Glyphosate in Older Adults Between 1993 and 2016 | Toxicology | JAMA | JAMA Network.” Accessed May 5, 2020. https://jamanetwork.com/journals/jama/fullarticle/2658306.

^[20] “Carcinogenicity of Tetrachlorvinphos, Parathion, Malathion, Diazinon, and Glyphosate – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/25801782/.

^[21] “Integrative Assessment of Multiple Pesticides as Risk Factors for Non-Hodgkin’s Lymphoma Among Men – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/12937207/.

^[22] De Roos, Anneclaire J., Aaron Blair, Jennifer A. Rusiecki, Jane A. Hoppin, Megan Svec, Mustafa Dosemeci, Dale P. Sandler, and Michael C. Alavanja. “Cancer Incidence among Glyphosate-Exposed Pesticide Applicators in the Agricultural Health Study.” Environmental Health Perspectives 113, no. 1 (January 2005): 49–54. https://doi.org/10.1289/ehp.7340.

^[23] “The Effects of Sub-Chronic Exposure of Wistar Rats to the Herbicide Glyphosate-Biocarb – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/15451553/.

^[24] “Glyphosate, Hard Water and Nephrotoxic Metals: Are They the Culprits Behind the Epidemic of Chronic Kidney Disease of Unknown Etiology in Sri Lanka? – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/24562182/.

^[25] “Glyphosate Suppresses the Antagonistic Effect of Enterococcus Spp. On Clostridium Botulinum – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/23396248/.

^[26] “Glyphosate Perturbs the Gut Microbiota of Honey Bees | PNAS.” Accessed May 5, 2020. https://www.pnas.org/content/115/41/10305.

^[27] Samsel, Anthony, and Stephanie Seneff. “Glyphosate, Pathways to Modern Diseases II: Celiac Sprue and Gluten Intolerance.” Interdisciplinary Toxicology 6, no. 4 (December 2013): 159–84. https://doi.org/10.2478/intox-2013-0026.

^[28] Samsel, Anthony, and Stephanie Seneff. “Glyphosate, Pathways to Modern Diseases III: Manganese, Neurological Diseases, and Associated Pathologies.” Surgical Neurology International 6 (March 24, 2015). https://doi.org/10.4103/2152-7806.153876.

^[29] Krueger, Monika & Schrödl, Wieland & Pedersen, Ib. (2014). Detection of Glyphosate in Malformed Piglets. Journal of Environmental & Analytical Toxicology. 04. 10.4172/2161-0525.1000230.

^[30] “Glyphosate-Based Herbicides Produce Teratogenic Effects on Vertebrates by Impairing Retinoic Acid Signaling – PubMed.” Accessed May 5, 2020. https://pubmed.ncbi.nlm.nih.gov/20695457/.

^[31] Myers, John Peterson, Michael N. Antoniou, Bruce Blumberg, Lynn Carroll, Theo Colborn, Lorne G. Everett, Michael Hansen, et al. “Concerns over Use of Glyphosate-Based Herbicides and Risks Associated with Exposures: A Consensus Statement.” Environmental Health 15 (February 17, 2016). https://doi.org/10.1186/s12940-016-0117-0.

^[32] “Sonoma County Restricts Use of Roundup, Other Synthetic Pesticides.” Accessed May 5, 2020. https://www.pressdemocrat.com/news/9668404-181/sonoma-county-restricts-use-of.

^[33] “Massive Study Finds Eating Organic Slashes Cancer Risks | EWG.” Accessed May 5, 2020. https://www.ewg.org/release/massive-study-finds-eating-organic-slashes-cancer-risks.

^[34] U.S. Right to Know. “Monsanto Roundup & Dicamba Trial Tracker.” Accessed May 5, 2020. https://usrtk.org/monsanto-roundup-trial-tracker-index/.