In February 2023, Mexican President Andrés Manuel López Obrador issued a presidential decree restricting the use of genetically modified (GM) corn in tortillas and other minimally processed corn products to protect public health and the environment. The U.S. government challenged those measures as unfair trade barriers under the U.S.-Mexico-Canada Agreement (USMCA).

In response to the trade dispute, Mexico has produced a series of scientific analyses and other documents in defense of its policies. The documents offer a comprehensive summary of the scientific evidence of health risks associated with GM corn and glyphosate.

• Read about the science in Mexico presented in our article, New scientific analyses underpin Mexico’s restrictions on GM corn and glyphosate due to health risks, by Timothy A. Wise and Stacy Malkan. November 27, 2024.
  
• Read an interview with Dr. María Elena Álvarez-Buylla, professor of molecular genetics, epigenetics, and development at Mexico’s National Autonomous University. Until the end of September, Dr. Álvarez-Buylla was the head of Mexico’s national science agency, CONAHCYT, the National Council of Humanities, Science and Technology. 

• Official documents are available in English and Spanish on the IATP resources page, along with more background and analysis. All dispute documents are available with free registration from the U.S. International Trade Administration site for the trade dispute.

CONAHCYT scientific analysis

This document compiling science on the health risks of GM corn and glyphosate was produced by CONAHCYT, Mexico’s National Council for Humanities, Science and Technology 

• Scientific Dossier on Genetically Modified Corn and its Effects: Effects of GM corn on human health, the environment and biodiversity, including the biocultural richness of native corn in Mexico, CONAHCYT, October 25, 2024. English translation prepared for U.S. Right to Know by Babel, a Mexico City translation firm. Here is the document in Spanish. 

Media coverage:

• Arman estudio sobre maíz transgénico para afrontar controversia en el seno del T-MEC, La Jornada, Sept. 30, 2024 
• Destacan efectos dañinos del maíz transgénico, La Jornada, Oct 28, 2024
• Maize continues to be the talk of the town, La Jornada magazine supplement, Ojarasca (p.18) November 2024. English translation and article in Spanish. 

Trade dispute documents and scientific analyses 

Key English language documents:

• Mexico’s Presidential Decree on GM Corn and Glyphosate (February 2023) 
• Initial written complaint by US: (January 2024) 
• Initial written submission of Mexican government (March 2024)
• US rebuttal, with science annexes (May 2024): 
• Mexico rebuttal, with appendices responding to US science annexes (June 2024)

Submissions from NGOs and expert witnesses

Submissions from non-governmental organizations invited by the trade tribunal (March 2024) are posted on the IATP resource page.

Analysis and resources 

Timothy A. Wise has been researching and writing about Mexican agriculture and the battle over GM corn for two decades. His past analysis and writings on GM corn in Mexico are available on his author page. His key recent publications on the trade dispute include:

• Analysis: Mexico Defends GM Corn Restrictions with Science: An analysis of Mexico’s response in the USMCA dispute, Timothy A. Wise, IATP Blog, March 14, 2024. (Also available in Spanish.)
• Analysis: Takeaways from Mexico’s final rebuttal in GM corn trade dispute, Timothy A. Wise, IATP Blog, June 20, 2024. (Also in Spanish on Contralinea)
• Science, Precaution, and Mexico’s GMO Corn Restrictions, Food Tank, February 15, 2023.
• Hardline U.S. Stance Ignores Non-GM Corn Opportunity for U.S. Farmers, Ken Roseboro and Timothy A. Wise, Food Tank, February 27, 2024. (Also published in Spanish on Contralinea in Mexico.)
• Mexico Calls U.S. Bluff on Science of GMO Corn Restrictions, Food Tank, March 30, 2023.
• Worlds Collide on Science of Public Health, IATP, June 20, 2023.
• U.S. Flails in GM Corn Dispute with Mexico, IPS News, August 19, 2024. (also available in Spanish)
• The US-Mexico Trade War Over GM Corn Heats Up, Truthdig, October 14, 2024. (In Spanish on Contralinea.)
• Chapter 7 from Wise’s book, title, publisher, year: Monsanto Invades Corn’s Garden of Eden in Mexico

More resources

• NGO webinar panel on science submissions to tribunal:  [Watch] Science, regulation & human health: Justifications for Mexico’s GM corn restrictions

• Expert Panel to Mexico GM Corn Tribunal: Respect the Science, Common Dreams, April 25, 2024. (Also in Spanish on Pie de Pagina and PopLab.)
  
• IATP analysis of the new Agricultural Biotechnology provisions in USMCA: Understanding the Agricultural Biotechnology Provisions in the U.S.-Mexico-Canada Agreement March 2, 2022
  
• Pervasive presence of transgenes and glyphosate in maize-derived food in Mexico,” Gonzalez-Ortega et al, Agriculture and Sustainable Food Systems, Sept. 2017. (Key journal article documenting GM corn and glyphosate in tortillas and other corn-based foods in Mexico.)

Media coverage of trade dispute

• Reuters report, March 6, 2024: Mexico waiting on US proof that GM corn safe for its people, deputy ag minister says

• The U.S.-Mexico tortilla war, Alexander Zaitchik, FERN & The Nation, May 28, 2024. (Also in Spanish from Contralinea.)

• Experts Warn of Toxins in GM Corn Amid US-Mexico Trade Dispute, Jessica Corbett, Common Dreams, March 26, 2024. [Cites FOE, CFS, and IATP comments and critiques]

• ‘We are defending your products:’ Emails reveal coordination between US government, industry in foreign trade disputes, Carey Gillam and Johnathan Hettinger, The New Lede, March 21, 2024. (submitted to the Guardian)

• Mexico smacks US over GM corn and glyphosate, Carey Gillam, Unspun, March 18, 2024.

• US health advocacy groups support Mexico in GMO trade dispute, Johnathan Hettinger, The New Lede, April 24, 2024.

• US says Mexico ‘abandoned science’ in GM corn limitations, Johnathan Hettinger, The New Lede, May 3, 2024.

• “The US-Mexico GMO Corn Standoff” – Two-part audio podcast interview with Tim Wise on Mexico’s GM corn fight, by Errol Schweizer, The Checkout, April 2024: Part 1 and Part 2. 

• Mexico Brings Science to a Trade Fight Over GMO Corn, Ernesto Hernandez-Lopez, Common Dreams, March 19, 2024.

• As Rumours Swirl That Mexico Has Lost USMCA Case on GM Corn Ban, Sheinbaum Pledges to Protect Mexico’s Native Corn, by Nick Corbishley. November 15, 2024