Conversation Questions Regarding Glyphosate

By Eric Sachs

Have questions about glyphosate, the main active ingredient in Roundup? We have answers.

See below for some of the top questions we’ve received on this subject through The Conversation. And if you have questions of your own, feel free to ask us

  1. Some studies have shown that consistent exposure to the glyphosates in Monsanto’s round up maybe causing health issues. Why use it?

Safety is a top priority for us at Monsanto. All of our herbicides including glyphosate are rigorously tested and then reviewed by third-party scientists at government agencies.

Glyphosate is one of the most widely used and thoroughly evaluated herbicides in the world. Many scientists have conducted studies and field research with glyphosate herbicides and published their results in peer-reviewed scientific journals. The overwhelming consensus is that glyphosate, when used properly, poses no adverse effects to people, wildlife or the environment.  To take just one example, three internationally recognized toxicologists published a peer-reviewed safety evaluation of glyphosate in 2000.  The authors reviewed over 188 documents, and concluded that glyphosate “is placed in U.S. EPA’s least toxic category (IV) for acute oral, dermal and inhalation toxicity.  Thus, [glyphosate] is considered to be practically nontoxic by all these routes of exposure.*”

Sustainability is also important to us. We’re trying to find ways to help farmers grow crops in ways that use resources efficiently and minimize impact on the environment. Glyphosate is one way we achieve this. 

*SOURCE: Safety Evaluation and Risk Assessment of the Herbicide Roundup and Its Active Ingredient, Glyphosate, for Humans, by Gary M. Williams, Robert Kroes, and Ian C. Munro, Regulatory Toxicology and Pharmacology, Volume 31, Pages 117-165 (2000).

  1. Have you done the research on the long-term effects of pesticides and herbicides that you use? How do we know they are truly not harmful?

We take the safety of the pesticide products we make, sell and use very seriously. All pesticide products (including herbicides) must go through regulation, including extensive safety testing and enforceable label instructions for safe use.  In the United States, for example, the EPA requires a thorough safety assessment for each pesticide product before it approves the product for sale and use in the U.S.  If you’d like more information about how the EPA evaluates the safety of pesticides, you can visit their website for a detailed explanation. You can also take a look at this article from Food Safety News, which discusses the safety of approved pesticide residues and tolerances.  

Glyphosate, an active ingredient in Roundup branded herbicides, has a long history of safe use.  Because sustainable agriculture is important to us, we’re always looking for ways to help farmers use resources efficiently while minimizing the environmental impact

  1. Is roundup eradicating the Monarch butterfly?

Experts who study butterflies say there are a number of factors that may contribute to the fluctuations in monarch populations migrating from the U.S. to Mexico at any given period of time, including logging of overwintering sites in Mexico, weather events (e.g., freezing temperatures and drought), predation, pathogens and parasites, availability of host plants and nectar sources across their migration range, and climate change.

Recent news coverage has narrowly focused on farming and farmers’ use of herbicides like glyphosate, which is a key ingredient of Roundup. We believe farming can coexist with natural wonders like monarch butterflies. That’s why Monsanto is working with experts from universities, nonprofits and government agencies to find ways to help monarchs. If you’re interested, this blog post on our website gives more details.

  1. Does the implementation of round-up ready crops lead to more use and dependence on glyphosate?

Farmers have choices when it comes to weed control, but yes, Roundup Ready crops have led to more farmers choosing to use of glyphosate. We believe that this is generally a good thing because glyphosate compares favorably to a lot of the herbicides it replaced. Check out this Biofortifed blog post that discusses how glyphosate compares to some other herbicides.

Plus, glyphosate is one of the most thoroughly evaluated herbicides in the world. When used according to label directions, glyphosate has a history of safe use for people, wildlife and the environment.

  1. Does spraying Round Up on the ground contaminate the drinking water below?

Because glyphosate–an active ingredient in Roundup agricultural herbicides–binds tightly to most soils, it has a low potential to move through soil to contaminate groundwater.


Glyphosate is one of the most thoroughly evaluated herbicide ingredients in the world, and while the Environmental Protection Agency, which is the U.S. agency that registers or licenses pesticides for use in the United States, prohibits absolute safety claims for all pesticide products (including those approved for use in organic production) they have determined that glyphosate, like other approved pesticide products, poses no unreasonable risk to people, wildlife or the environment.

If you’re interested in learning more about glyphosate, check out these background materials on our website.

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