Glyphosate

By Jade Greene 

This potent and controversial herbicide has been in the news lately as President Trump signed an executive order directing the Secretary of Agriculture to boost the domestic supply of glyphosate. Why does this matter for farms, people, and the environment? 

What is Glyphosate?

Glyphosate (pronounced gly-fow-sate) is a synthetic compound originally developed as a water-softening agent. Researchers later discovered that it was highly effective at killing weeds. It is most commonly marketed under the trade name Roundup and has become the most widely used herbicide in the United States.

While this article focuses on agricultural use, glyphosate is also commonly applied by land managers to control invasive species, and by landscaping companies and homeowners to manage weeds in lawns and garden beds.

How Does It Work?

Glyphosate works by interfering with the shikimate pathway in plants, which prevents them from producing essential amino acids. Without these amino acids, the plant cannot survive.

It is minimally absorbed through plant roots and is most effective when sprayed directly on leaves. Many formulations include a surfactant, which helps the product adhere to leaf surfaces. Each year, hundreds of millions of pounds are used to control a wide variety of grasses, broadleaf weeds, and woody plants. (source)

How and Why Do Farmers Use It?

Weeds are the bane of every farmer’s existence. Weeds compete with crops for nutrients, water, light, and space, reducing yields and profitability. Managing weeds is one of the central challenges of farming.

Historically, farmers controlled weeds through tillage, the process of turning over the soil to disrupt weed growth. While effective, frequent tillage leads to soil erosion and the loss of valuable topsoil. As soil conservation practices gained traction in the mid-20th century, many farmers sought alternatives as they turned away from tilling. Enter – herbicides. 

Herbicides became the primary solution to weeds on conventional farms. Glyphosate, first introduced for agricultural use in 1974, is a non-selective herbicide, meaning it kills most plants it contacts.

A major shift occurred in 1996 with the introduction of “Roundup Ready” crops, genetically modified varieties of corn, soybeans, and other crops engineered to tolerate glyphosate. This allowed farmers to spray fields to kill weeds without harming the crop itself, dramatically increasing glyphosate use.

Glyphosate is the most used herbicide in the United States. It has become ubiquitous and essential to large, conventional farms. Many farmers know no other way to control weeds and rely on artificial amends to get crop yields.

Glyphosate is prohibited in organic farming and other methods (explored further below) have been employed to reduce weeds.

Farmer applying Glyphosate to a monoculture field.

Why is it a Problem?

Manufacturers argue that glyphosate does not harm humans or animals because they do not possess the shikimate pathway found in only plants. However, concerns remain.

Human Health Concerns:

• In 2015, the International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic to humans,” citing links to non-Hodgkin lymphoma and other cancers (source, source).
• Glyphosate residues have been detected in food products, and debate continues over the long-term health implications of chronic, low-level exposure (source).
• Surfactants added to glyphosate formulations have been shown to cause acute and chronic health effects (source).
• Glyphosate has a negative effect on both the human microbiome because many bacteria also use the shikimate pathway (source).

The U.S. Environmental Protection Agency (EPA), however, has concluded that glyphosate is “not likely to be carcinogenic to humans” when used according to label instructions. (source) The White House has made their position clear with the recent executive order directing the Secretary of Agriculture to boost the domestic supply of glyphosate.

Interestingly enough, since 2021, the main chemical in Roundup sold for residential use was quietly switched from glyphosate to other, unknown-to-the-public herbicides, after many cancer lawsuits we filed (source).

Environmental Concerns:

• Mining Phosphate: To produce glyphosate, phosphate as raw material is required, which can not be synthesized in a laboratory. Phosphate is only found in a few areas of the world, including Florida, Idaho, and China. Rock phosphate is mined using invasive techniques that “involves stripping away the soil off mountaintops, which destroys vegetation, contaminates water and creates noise and air pollution that is detrimental to wildlife and the environment for years to come.” (source)
• Soil Health: Glyphosate binds tightly to soil particles, which can allow it to accumulate in soil or move into waterways through erosion and runoff (source). Some research suggests it may interfere with plant uptake of certain micronutrients (source), leading to weakened plants and less nutrient dense food for people. Additionally, soil microbiome is negatively impacted as many bacteria also use the shikimate pathway (source).
• Herbicide Resistance (aka “Superweeds”): Just as antibiotic overuse has led to resistant bacteria, repeated herbicide use has led to herbicide-resistant weeds, nicknamed “superweeds.” Species like Palmer amaranth have developed resistance to glyphosate, forcing farmers to use additional or older herbicides and, in some cases, abandon heavily infested fields (source).
• Aquatic Health: Glyphosate can enter waterways through runoff, particularly if applied before rainfall. Studies have found that glyphosate and surfactants may negatively affect fish, amphibians, and aquatic invertebrates (source).

A phosphate mine, Case Western Reserve University

What are Alternatives?

Reducing glyphosate use, especially on large conventional farms, can be challenging, but many farmers are already implementing alternative approaches that emphasize soil health and ecological balance. These include:

• Crop rotation and crop diversity, which help break weed, pest, and disease cycles
• Cover cropping, which suppresses weeds and protects soil between main crops
• Building soil fertility, so crops are more competitive against weeds
• Hand weeding
• Organic-approved herbicides

Regenerative and organic farms in Bucks County are using these practices successfully. You can explore local farms on our Local Food Map.

Cover crops and crop diversity on display at Bluestem Botanicals.

Learn More

To dive deeper into the connection between soil health, farming practices, and human health, join us for What Your Food Ate & Why It Matters on April 9 at Delaware Valley University. Anne Biklé, along with a panel of doctors and farmers, will explore how the way we grow food impacts both ecosystem and human well-being. Tickets and more information can be found here.

Do you think we should ramp up domestic supply of glyphosate or focus on alternative, regenerative approaches?

Sources:

• Civil Eats – Roundup’s Other Problem: Glyphosate is Sourced from Controversial Mines
• Forbes – Roundup Lawsuit Update
• International Agency for Research on Cancer – IARC Monograph on Glyphosate
• National Library of Medicine – Computational modelling provides insight into the effects of glyphosate on the shikimate pathway in the human gut microbiome
• National Library of Medicine – Glyphosate, Roundup and the Failures of Regulatory Assessment
• National Library of Medicine – Glyphosate surfactant herbicide poisoning and management
• National Pesticide Information Center – Glyphosate Technical Fact Sheet 
• US Environmental Protection Agency – Glyphosate