By Steve Levine, Ph.D., Senior Science Fellow
Ecotoxicology and Environmental Risk Assessment, Lead
Just last week, a comprehensive U.S. Environmental Protection Agency (EPA) screening program confirmed that glyphosate, a primary ingredient in Roundup brand herbicides, is not an endocrine disruptor. As a long-time Monsanto scientist who has spent my career studying the health and safety of pesticides, including glyphosate, I was happy to see that the safety profile of one of our products was upheld by an independent regulatory agency.
I know that farmers, gardeners and other users rely on this herbicide because of both its effectiveness and its extremely favorable safety profile. Glyphosate’s safety is supported by one of the most extensive worldwide human health databases ever compiled on an agricultural product.
Why does the EPA test for endocrine disruptors?
An endocrine disruptor is a chemical substance that alters the function of the hormonal system and, consequently, causes an adverse effect in a living organism or its offspring. The likelihood such a chemical will cause harmful effects is based on its mode of action, potency and potential for real-world exposure.
Glyphosate was one of more than 50 initial chemicals reviewed as part of EPA’s comprehensive Tier 1 Endocrine Disruptor Screening Program. This program has been under way for years and is mandated by the Food Quality Protection Act (FQPA). Congress enacted FQPA in 1996, and the Act standardized the way the EPA manages the use of pesticides. The Act also directed the U.S. EPA to develop and implement a validated screening and testing program to investigate the potential of chemicals to induce adverse effects through endocrine pathways. I had the opportunity to leverage my expertise in this field and was selected to serve on EPA’s Endocrine Disruption Method Validation Advisory Committee and other federal and international review committees that developed the battery of assays used to assess chemicals for potential endocrine activity.
As part of its comprehensive review program, EPA looked at 11 different validated assays assessing the potential for effects of glyphosate on endocrine pathways in humans and wildlife that are important for growth, development and reproduction. Based on its review of the data, EPA concluded “there was no convincing evidence of potential interaction with the estrogen, androgen or thyroid pathways.” This conclusion is consistent with results from a large body of existing human and wildlife safety studies conducted in accordance with international testing and assessment guidelines.
From the start, EPA was very clear that glyphosate was included on the initial list of compounds to be screened because it met specific exposure criteria; it was not because of any belief that glyphosate could cause endocrine effects. In other words, because glyphosate is used commonly in agriculture, in public spaces and around the home, EPA included it on its initial list. As EPA clearly stated, “Nothing in the approach for generating the initial list provides a basis to infer that by simply being on the list these chemicals are suspected to interfere with the endocrine systems of human or other species, and it would be inappropriate to do so.”
Testing Monsanto’s products for safety
The safety of our products is of the utmost importance to everyone at Monsanto, and we conduct rigorous testing on every product we put on the market. We also provide extensive data to independent experts and are required to provide data to government agencies so that they can evaluate the safety of our products as well.
We are pleased that EPA has completed a rigorous, comprehensive and science-based review of glyphosate. This assessment should give farmers, consumers and other users of glyphosate added assurance about the safety of this important pesticide product.