- A constitutional ban on transgenic corn production in Mexico is expected to be approved this month and has been lauded by the government as a measure to protect the country’s native corn varieties.
- In recent years, Mexico issued controversial presidential decrees to ban human consumption of transgenic corn and its use in dough and tortillas, claiming genetically modified varieties have adverse health impacts.
- Mexico is the largest importer of U.S. transgenic corn, and in December, an independent USMCA panel ruled the claims that consumption causes negative health impacts weren’t scientifically supported.
- Mexico’s large-scale import of U.S. genetically modified corn is considered by local experts to be a risk to small and Indigenous farmers, as they say it exposes native species of the crop to potential cross-pollination with transgenic seeds.
This month, Mexico’s two legislative houses are expected to approve an amendment that will prohibit the cultivation of transgenic corn in the country’s Constitution, a historic decision that farmers’ organizations and leaders of the national agricultural industry are applauding — though not fully celebrating.
While the constitutional change proposed by President Claudia Sheinbaum will ban nationwide production of transgenic corn in Mexico, the import and human consumption of genetically modified corn will still be permitted in the country as will the use of the herbicide glyphosate. In December, an independent panel ruled in favor of the U.S., stating that Mexico’s efforts to ban the importation of transgenic corn on human health grounds weren’t scientifically supported.
This continued import of large-scale U.S. genetically modified corn is considered to be a threat by local experts, who assert the transgenic seeds — as well as the herbicide glyphosate commonly used in their production — represent a threat to native species of the crop that have existed for thousands of years and continue to be produced by small and Indigenous farmers nationwide.
Given that Sheinbaum’s Morena Party holds a majority in both legislative houses, the constitutional amendment is likely to pass with ease in the upcoming weeks, as has been the case with several other recently approved reforms.
“The constitutional reform is a good and positive step,” said María Leticia López Zepeda, executive director of the National Association of Commercial Businesses for Farmers (ANEC). “But it doesn’t protect all the country’s corn, which to us as Mexicans is part of our identity, our biodiversity and our culture.”
Mexico is the birthplace of modern corn, and the import of genetically modified varieties from the U.S. into the country has been a long-standing point of contention among national farming groups, multinational seed producers, political parties and nongovernmental organizations. Mexico is the largest export destination for U.S. produced corn and, from January through October 2024, the U.S. sent $4.8 billion worth of corn to Mexico. Most of the U.S. corn sent to Mexico is genetically modified, and in the U.S. more than 90% of the nation’s corn is produced using the technique.

While Mexico produces white corn, it uses the U.S. imported yellow corn as feed for livestock animals and in industrial operations. A prevailing fear of many industry members in Mexico is that the genetically modified yellow corn seeds will mix with native varieties of the crop that have been cultivated for centuries by small and Indigenous farmers. There are at least 59 different varieties of corn harvested by more than 4 million farmers nationwide, and the white variety of the crop is used in many of Mexico’s staple and most emblematic foods — tortillas, tamales, dough, esquites, flour, cornmeal, soups and beverages — and is a symbol of national identity and pride.
Furthermore, experts argue that the constitutional amendment to prohibit the cultivation of transgenic corn acts solely as a formalization of an existing ban, issued in 2013, that already outlawed the practice in Mexico. They claim that the new legislation, while a positive step, comes up short in offering more protections to small and Indigenous farmers trying to keep genetically modified seeds imported from the U.S. from pollinating their land and crops.
“Unfortunately, what we’re seeing is that native varieties of corn are now very contaminated by transgenic seeds and that the spread has advanced,” said Tania Montserrat Téllez Serrano, coordinator of political impact at the civil society organization Semillas de Vida. “It is principally Indigenous communities that have conserved the diversity of our native corn and seeds, which are passed down by families and communities to harvest the crop for consumption. The risk is that the imported genetically modified seeds will be integrated into these communities and that the native varieties will be lost.”

Corn and the USMCA
Corn is one of Mexico’s most sacred crops and, while its original production dates back some 10,000 years, its emergence as a hot-button political issue between Mexico and the U.S. began 31 years ago, following the 1994 passage of the North American Free-Trade Agreement, now known as the United States-Mexico-Canada Agreement, or USMCA.
In 1994, Mexico began to import low-cost U.S. corn, despite that the country produced enough corn to meet national consumption and feedstock demands at that time, according to María Elena Álvarez-Buylla, former director of Mexico’s Science and Technology Council (CONACYT).
“It was at that point Mexico abandoned food self-sufficiency in favor of a competitive market,” López at ANEC said. “The rationale was that if corn production is not profitable and that it requires a lot of work to cultivate it, why don’t we just import it for cheaper?”
Both López and Álvarez-Buylla, who was the director CONACYT during the administration of former President Andrés Manuel López Obrador, claim that it was the adoption of these free market, neoliberal policies that allowed for genetically modified corn to enter the country, thus jeopardizing the country’s native corn varieties and the harvests of small and Indigenous farmers.
“In Mexico our Indigenous and small farming communities have demonstrated a robust resistance to these neoliberal efforts and aren’t willing to abandon cultivation of their native corn species nor self-sustenance,” Álvarez-Buylla said. “Mexico is fully capable of producing its own yellow corn to feed its livestock and meet industrial needs, and I think it would benefit Mexico to return to produce what we need and cease to import transgenic corn, which uses large quantities of agrochemicals that have negative health impacts, such as glyphosate.”
This debate — whether transgenic and genetically modified corn have negative health impacts — has been a central issue between Mexico and the U.S. in recent years, particularly in the context of the USMCA.

In 2020, former President López Obrador issued a decree that ordered a gradual phaseout of transgenic corn and glyphosate use in the country by 2024, claiming both were damaging to the health of Mexican citizens. In 2023, he issued an updated decree, which prohibited human consumption of genetically modified corn, particularly in tortillas and dough. These decrees faced resistance from the U.S. and ultimately led to a legal dispute under the USCMA.
On Dec. 20, the U.S. announced that an independent panel had ruled in its favor and that Mexico’s claims that transgenic corn has negative health impacts “are not based on science and undermine the market access that Mexico agreed to provide in the USMCA.”
“Whoever says that transgenic corn has a negative health impact is lying,” said Juan Cortina, president of Mexico’s National Agriculture Council. “We’ve been using transgenic corns in Mexico for 30 years, as well as in the rest of the world, and nothing has been proven to support claims that there is any health impact.”
Because Mexico lost the ruling, the phaseout of glyphosate and import ban on it were, in effect, also canceled.
Cortina added that glyphosate is used on many crops in large-scale harvests, such as sorghum, soybeans and berries, and that it is only contaminating when used irresponsibly or in excess.
“In the U.S., there are hundreds of thousands of hectares that use glyphosate in the production of corn, and there aren’t any health problems associated with it,” he said.
The debate over the potential health impacts of glyphosate has persisted for years. While the Environmental Protection Agency determined in 2020 that “that there are no risks of concern to human health when glyphosate is used in accordance with its current label,” in 2023, Michael Antoniou, a professor of molecular genetics and toxicology at King’s College London, wrote that “in studies on animals exposed to regulatory-relevant doses of glyphosate and commercial glyphosate-based herbicide formulations, adverse effects were observed in multiple organs and systems.”
Antoniou concluded that “the consumption of imported US GM corn at the high levels typical for Mexican citizens has the potential to result in serious negative health outcomes.

Without corn, there is no country
President Sheinbaum’s decision to seek the constitutional ban of domestically produced transgenic corn is considered by many in the industry to be a sign of things to come during her administration. The USMCA will likely be a prominent topic of debate throughout her government, particularly during a heated trade environment with U.S. President Donald Trump, who had threatened to impose 25% tariffs on all Mexican goods entering the U.S. beginning in February (Trump has since paused the tariffs for 30 days).
While Sheinbaum’s initial move to improve control over Mexico’s corn industry was seen by some as too soft or watered down, sources say it sets the stage for what will likely be continued debate over the bilateral corn relationship. Sheinbaum, similar to López Obrador, has decried neoliberal economic policy that she claims stripped Mexico of some of its most emblematic institutions and agricultural products, such as corn.
“Without corn, there is no country,” Sheinbaum said in public comments Jan. 26, repeating a popular national refrain in Spanish: Sin maíz no hay país. “Our corn has enormous genetic diversity, which is part of our culture and biological diversity. We will protect it.”
Banner image: A variety of corns and beans native to Mexico. Image by Alan de La Cruz via Unsplash (Public domain).
Indigenous Comcaac serve up an oceanic grain to preserve seagrass meadows