Glyphosate, also known commercially as Round Up, is one of the most widely used herbicides that has been adopted by farmers around the world.

You may be confused if glyphosate is safe or not as there is conflicting opinions and evidence. A United Nations agency believes that it is carcinogenic, however the Environmental Protection Agency says it is safe to use if the manufacturer’s instructions are followed. The below evidence extracted from 14 scientific journals strongly refutes the EPA’s stance and shows how harmful this toxic herbicide is in a variety of ways, from being a tumour promotor, impairing behaviour, gut health and fertility as well as having negative consequences on wildlife.

Cancer & Tumors

A study published in the journal of Food and Chemical Toxicology in September 2013 found that “Glyphosate induces human breast cancer cell growth via estrogen receptors” [8].

A study published in 2014 in the Journal of Environmental Science Europe found that “rats fed GM maize and/or Roundup in their water over their entire lifespan revealed significantly increased risk of massive mammary tumours in the females, along with kidney and liver damage… The exposed animals also had a shortened life span compared to the controls“ [3].

“A 26-month long-term study in rats conducted by Bio/dynamics revealed multitudes of tumours in glands and organs. They occurred (from highest to lowest incidence) in the following organs: pituitary, thyroid, thymus, mammary glands, testes, kidney, pancreas, liver and lungs. Pituitary, thyroid and thymus glands control body and immune function, and disruption can induce disease, including cancer.” [4]

Behaviour Impairment

“Glyphosate-based herbicides have been shown to induce behavioural impairments, and “Glyphosate-based herbicide exposure leads to despair behaviour.” The data from this study reinforces “the essential link between gut microbiota and toxicity in mice and suggest that observed intestinal dysbiosis could increase the prevalence of neurobehavioral alterations.” [2]

In May 2019 a study published in the Journal of Neuroendocrinology found that “glyphosate‐based herbicide exposure during the peripartum period affects maternal brain plasticity, maternal behaviour” in rats. [9]


A study published in December 2017 on human sperm concluded, “at the particular dose used in the present study, Roundup can cause male sub-fertility.” The amount of Round Up used in the study was “at the relatively low concentration of 1 mg/L (which) has adverse effects on sperm motility, and this may be related to the observed reduction in mitochondrial staining.” [10]

Another study published in 2019 in the Science of the Total Environment states “our results also show that exposure to low, environmentally relevant concentrations of Roundup® can also impair planarian sexual reproduction… Glyphosate and glyphosate-based herbicides have been shown to decrease the reproduction of aquatic vertebrates and invertebrate organisms.” [12]

A published study released in 2019 states that crabs exposed to 1mg/L if glyphosate for one month showed “significant decrease in sperm count”, “lower sperm count was also observed in vitro, in gonads exposed to glyphosate” and “an apparent interference of glyposate with the androgenic gland was seen in vitro.” [14]


A study on four frog species published in the journal of Environmental Toxicology in 2009 “showed decreased snout‐vent length at metamorphosis and increased time to metamorphosis, tail damage, and gonadal abnormalities. These effects may be caused, in some part, by disruption of hormone signalling, because thyroid hormone receptor β mRNA transcript levels were elevated by exposure to formulations containing glyphosate.” [5]

A study conducted in 2016 and published in the Environmental Toxicology and Pharmacology journal concludes “that glyphosate and the Roundup® formulation is developmentally toxic to the forebrain and midbrain” in zebrafish [6].

A journal review published in August 2019 states “that glyphosate perturbed the gut microbiota of honeybees, which led to a negative impact on the overall health of the hosts and allowed for increased vulnerability to pathogens and malnutrition”. [13]

Gut Health

In January 2019 a study published in NeuroToxicology found glyphosate causes gut “dysbiosis, a phenomenon which is characterised by an imbalance between beneficial and pathogenic microorganisms. The overgrowth of bacteria such as clostridia generates high levels of noxious metabolites in the brain, which can contribute to the development of neurological deviations.” [1]

In May 2019 a study published in the Journal of Neuroendocrinology found “that gut microbiota is significantly altered by the exposure to the pesticides, with significant alteration of the phyla Bacteroidetes and Firmicutes” in rats. [1]

A study released in 2019 concludes that “Environmental pollutants insecticides or herbicides as glyphosate produce intestinal dysbiosis” and that “Glyphosate impacts on central nervous system and others neurobiological disorders, due to the gut-brain axis.” [2]


1. Yassine Aitbali, Saadia Ba-M’hamed, Najoua Elhidar, Ahmed Nafis, Nabila Soraa, Mohamed Bennis (May–June 2018). “Glyphosate based- herbicide exposure affects gut microbiota, anxiety and depression-like behaviours in mice” Journal of Neurotoxicology and Teratology.

2. Rueda-Ruzafa, L., Cruz, F., Roman, P., Cardona, D. (December 2019) “Gut microbiota and neurological effects of glyphosate.” Journal of NeuroToxicology.

3. Séralini, G.E., Clair, E., Mesnage, R., Defarge, N., Malatesta, M., Hennequin, D. & Spiroux de Vendômois, J. “Republished study: Long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize”. Environ. Sci. Eur. 26 (2014) 14.

4. Samsel, A., Seneff, S. (2015) “Glyphosate, pathways to modern diseases IV: cancer and related pathologies.

5. Howe. C, Berrill. M, Pauli B, (2009) Toxicity of glyphosate‐based pesticides to four North American frog species. Journal of Environmental Toxicology.

6. Nicole M. Roy, Bruno Carneiro, Jeremy Ochs, (2016) “Glyphosate induces neurotoxicity in zebrafish” Journal of Environmental Toxicology and Pharmacology.

7. Thongprakaisang S., Thiantanawat, A., Rangkadilok, N,. Suriyo, T,. Satayavivad, J., “Glyphosate induces human breast cancer cells growth via estrogen receptors”. Journal of Food and Chemical Toxicology. Volume 59, September 2013, Pages 129-136

8. Dechartres, J., Pawluski, J., Gueguen, M. et. al (07 May 2019) “Glyphosate and glyphosate‐based herbicide exposure during the peripartum period affects maternal brain plasticity, maternal behaviour and microbiome”

9. Anifandis, G., Amiridis, G., Dafopoulos, K., Daponte, A., Dovolou, E., Gavriil, E., Psarra, A. G. (2017). The In Vitro Impact of the Herbicide Roundup on Human Sperm Motility and Sperm Mitochondria. Toxics, 6(1), 2.

10. Zhang, L., Rana, I., Shaffer, R., Taioli, E., & Sheppard, L. (2019). Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence. Mutation Research/Reviews In Mutation Research, 781, 186-206. doi: 10.1016/j.mrrev.2019.02.00

11. Rueda-Ruzafa, L., Cruz, F., Roman, P., & Cardona, D. (2019). Gut microbiota and neurological effects of glyphosate. Neurotoxicology, 75, 1-8. doi: 10.1016/j.neuro.2019.08.006

12. Córdova López, A., Sarmento, R., de Souza Saraiva, A., Pereira, R., Soares, A., & Pestana, J. (2019). Exposure to Roundup® affects behaviour, head regeneration and reproduction of the freshwater planarian Girardia tigrina. Science Of The Total Environment, 675, 453-461. doi: 10.1016/j.scitotenv.2019.04.234

13. Ledoux, M., Hettiarachchy, N., Yu, X., Howard, L., & Lee, S. (2019). Penetration of glyphosate into the food supply and the incidental impact on the honey supply and bees. Food Control, 106859. doi: 10.1016/j.foodcont.2019.106859

14. Canosa, I., Zanitti, M., Lonné, N., Medesani, D., López Greco, L., & Rodríguez, E. (2019). Imbalances in the male reproductive function of the estuarine crab Neohelice granulata, caused by glyphosate. Ecotoxicology And Environmental Safety, 182, 109405. doi: 10.1016/j.ecoenv.2019.109405

By nutritionist Chrissy

Chrissy is a university qualified nutritionist who graduated with honours at La Trobe University in Melbourne. One of her favourite hobbies is to read the scientific literature on how to optimise health. When she’s not reading, writing or working she’s with her 3 children outdoors, practicing yoga, jogging or cooking up a storm in the kitchen. Chrissy has overcome some debilitating chronic health issues (low mood, adrenal fatigue, insomnia, very bad acne to name a few) with the power of nutrients and correcting gut health, at 39 she now feels better than she did in her 20’s.