Health Concerns Over Roundup Herbicide and Glyphosate Exposure

Dark Leafy Greens Are a Source of Folate
Chemicals Being Applied to a Crop Field

Glyphosate is the most widely used chemical herbicide in the world. Originally introduced commercially as Roundup, the formulation is now off patent with multiple companies producing similar products. Herbicides are chemicals used to prevent weeds or other undesirable plants from growing. When the agricultural company Monsanto first made genetically modified corn and soybeans that were resistant to glyphosate exposure, it dramatically increased the use of the herbicide on crop fields. Recent data suggests global usage of glyphosate is in excess of 825 million kilograms or 1.8 billion pounds per year (Benbrook 2016).

And while the safety of glyphosate has long been touted by Monsanta, data suggesting potential harms has slowly been building. Considering how much glyphosate is used, human exposure through the environment and the food chain is inevitable. Somewhat shockingly, the FDA only started testing food for glyphosate residues in 2016 (FDA 2022). Yet the amount of published data available on actual human exposure levels is extremely minimal. Of the data that we do have, children appear to have higher exposure than adults, ranging from 0.28 μg/L to 4.04 μg/L found in urine samples (Gillezeau 2020). 

Regulatory Problems

Similar to problems in the pharmaceutical industry, the bodies that regulate pesticide and herbicide use have close ties to industry. This creates a revolving door, with regulators having financial ties to the industry they are regulating (Novotny 2022). Obviously, this is less than ideal and often promotes industry friendly, non-scientific regulations that may not be in the public’s best interest. 

One of the biggest failures in glyphosate regulation is that most testing focuses just on glyphosate, the “active ingredient,” and not the entire Roundup herbicide formulation. Considering that other components in Roundup have been estimated to be one-thousand times more toxic than glyphosate, this feels like a considerable oversight (Seralini 2015). Research on these adjuvant compounds shows that they may disrupt both the nervous system and the hormonal systems of the human body. 

Health Effects of Glyphosate

Cancer

In 2015, the International Agency for Research on Cancer concluded that glyphosate is a probable carcinogen based on published animal studies and human exposure data (IARC 2015). Research suggests that glyphosate can damage human deoxynucleic acid (DNA) which may be of particular relevance for inducing some types of blood cancer (Marino 2021). 

Arguments have been raised back and forth, with some groups showing no association between glyphosate exposure and blood cancers (Boffetta 2021), while others have found a link (Zhang 2019). One research group pointed out that the differing results were based on assumptions around potential exposure levels and the time it takes for cancer to develop (Kabat 2021). It’s a simple reminder about how study methodology can profoundly change research outcomes. 

Other recent research on prenatal exposure to pesticides, including glyphosate, shows potential risks. Neuroblastomas, a type of childhood cancer, has also been linked to prenatal glyphosate exposure and may be of concern (Khan 2022). 

Toxic Effects on the Nervous System

A similar pattern emerges in the research on the effects of glyphosate on the nervous system. While some meta-analyses are adamant as to a lack of negative effects (Moser 2022, Chang 2022), other studies are just as adamant that glyphosate exposure produces clear alterations in both the structure and function of the human nervous system (Costas-Ferreira 2022). Based on the published studies, it appears likely that glyphosate can disrupt brain cell communication, increase oxidative stress and inflammation in the central nervous system and cause problems with cellular energy production (Costas-Ferreira 2022).  

Reproductive Harms

A recent meta-analysis exploring hormonal changes in animal studies due to glyphosate exposure came to a stark conclusion. Based on lowered testosterone levels and effects on other hormone levels, the researchers concluded that glyphosate “could have major effects on the health of the reproductive system.” They stated that monitoring of glyphosate levels in food and water should be considered a necessity to protect human reproductive health (Mohammadi 2021).  

Gastrointestinal Damage

Another concern from glyphosate formulations is damage to the gastrointestinal system. Animal studies have shown that glyphosate causes damage to the gut microbiota, the healthy bacteria that line the gastrointestinal tract. One study found that low-dose, lifelong exposure caused intestinal damage, negative changes to gut flora and behavioral changes in mice (Del Castilo 2022).

A separate study in rats found that glyphosate exposure damaged gut flora in ways that led to male reproductive toxicity (Liu 2022). A combination oral and inhalation study of glyphosate in rats found that exposure caused oral allergies and precancerous lesions throughout the digestive system (Serra 2021). 

Chemical Application to a Farm Field

A review article in 2019 describes how glyphosate inhibits an important enzyme found in the beneficial bacteria along the digestive tract, while sparing pathological organisms. This may explain the damage seen to the gut flora, allowing for these “bad” bacteria to overgrow. In the article, the authors speculate that these bacteria may produce toxins that can have negative effects on the central nervous system, possibly leading to behavioral disorders or other negative mental health outcomes. However, the authors caution that more research is needed to fully understand the potential effects (Ruzafa 2019).  

Antibiotic-Resistant Bacteria

Antibiotic-resistant bacteria are a growing problem. As bacteria become resistant to more and more antibiotics, bacteria that are completely resistant to treatment are starting to emerge. The risks of a post-antibiotic world could make regular surgical and other standard medical procedures life-threatening due to untreatable infections. And while overuse of antibiotics is a major culprit for producing antibiotic resistance, evidence is also pointing to glyphosate as a potential cause. 

Recently, multidrug-resistant bacteria have been emerging from countries clustered around the equator. Interestingly, standard antibiotic use is quite low in many of these countries, suggesting some other mechanism for the emergence of antibiotic resistance. Since glyphosate acts as an antibiotic, the emergence of resistant bacteria could be due to high levels of glyphosate exposure. While standard antibiotic use is low in these countries, glyphosate use is often exceedingly high, typically to treat glyphosate-resistant crops (Raoult 2021). Studies have shown increased levels of antibiotic-resistance genes and greater swapping of genetic resistance between bacterial species with exposure to herbicides, including glyphosate (Liao 2021). The data available raises significant concerns, however, more research is needed to know the full real-world effects.

Conclusion 

The health effects of glyphosate are controversial. However, data continues to accrue showing potential concerns for numerous negative effects on health, from cancer to intestinal damage, to the development of antibiotic-resistant bacteria. Based on the data, valid concerns exist for the health effects of glyphosate. Hopefully, with more awareness and more research, safer approaches to herbicides and weed control can emerge, reducing our reliance on chemicals with potentially negative consequences on human health. 

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