Mexico’s act of resistance over GM corn

By Timothy Wise

On March 17, Mexican President Claudia Sheinbaum Pardo signed into law a constitutional reform banning the cultivation of genetically modified corn. The action followed a December ruling by a trade tribunal, under the US-Mexico-Canada (USMCA) trade agreement, in favor of a US complaint that Mexico’s 2023 presidential decree, with broad restrictions on the consumption of GM corn, constituted an unfair trade practice by prohibiting the use of GM corn in tortillas.

The Mexican government publicly disagreed with the ruling, claiming that the arbitrators had failed to consider the scientific evidence Mexico presented in the yearlong case. But the government chose to comply, rescinding the three specific parts of the decree deemed by the panel to limit future GM corn imports. Still, the government left intact the decree’s measures phasing out the use of the herbicide glyphosate, establishing a protocol for tracking GM corn imports into the country, and banning the cultivation of GM corn in the country.

 The constitutional amendment enshrines that last measure in a more permanent manner. While GM corn has faced planting restrictions for more than a decade, the constitutional ban represents an important act of resistance and sovereignty, particularly in light of the flawed decision by the tribunal.

Trade panel fails to consider evidence

Corn is central to Mexico’s agriculture, cuisine, nutrition, and culture. Mexico is the center of origin for corn, where the crop was domesticated thousands of years ago. It remains at the core of the country’s farming, diet, and culture. As President Sheinbaum acknowledged in approving the constitutional ban on GM corn cultivation, “Sin maiz no hay pais” – without corn there is no country.

Mexico presented strong evidence that GM corn has cross-pollinated native corn varieties, gene flow that threatens to undermine the genetic integrity of the country’s 64 “landraces” and more than 22,000 varieties adapted by farmers over millennia to different soils, altitudes, climates, foods, and customs. 

In defense of Mexico’s 2023 decree, the panel acknowledged that the government presented scientific evidence from qualified and reputable sources of “risks to human health arising from the direct consumption of GM corn grain in Mexico, and risks to native corn of transgenic contamination arising from the unintentional, unauthorized, and uncontrolled spread of GM corn in Mexico.” (That evidence is summarized in an extensive publication from Mexico’s national science agency, CONAHCYT.)

The trade tribunal dismissed concerns about such risks in its ruling, in the process repeating several fallacies about the robust scientific evidence presented by the Mexican government. In effect, the tribunal gave itself a pass on reviewing the scientific evidence of risks to human health by ruling that Mexico had not conducted an approved risk assessment “based on relevant scientific principles,” a reference to prevailing international codes for such processes. 

The panel also failed to evaluate the evidence of risks to native corn. The tribunal argued that no special protection from GM corn was needed because gene flow already takes place from non-GM hybrid varieties of corn, and GM contamination is no different from non-GM gene flow. “Mexico has not demonstrated how the threat to the traditions and livelihoods of indigenous and farming communities from GM corn is greater than the threat posed by non-native, non-GM corn,” the panel wrote. 

This lazy logic flows easily from biotech industry talking points, and it makes no sense at all in the birthplace of corn. In effect, the tribunal claimed that cross-pollination from hybrid corn, “could equally threaten the genetic integrity of native corn.” The discredited notion of “substantial equivalence” between GM crops and their conventionally bred hybrid counterparts has been further undermined by new research techniques that show distinct gene expressions in the cells of GM plants. 

Those techniques were explained in some detail in expert testimony submitted by molecular geneticist Michael Antoniou, but the panel never got his testimony translated, nor those of three other experts. Not surprisingly, the ruling had no mention of Dr. Antoniou’s contribution.

Equating contamination from GM corn with that of hybrid corn is a serious misreading of the science and of Mexico’s culture. GM by definition – and by explicit definitions in the constitutional amendment – involves crossing species boundaries, introducing, for example, a gene from a bacterium into a corn plant to repel insects. In contrast, hybrid corn is produced by cross-breeding different corn varieties. The resulting hybridized offspring remains pure corn, with no non-corn genes in its DNA. 

Mexican farmers have a long history of developing some of their own cross-pollinated varieties, intentionally combining a native variety with a hybrid that has properties the farmer desires. Mexican agronomists sometimes call these criollo varieties, which continue to be open-pollinating, by design, so farmers can propagate them themselves. 

Such cross-pollination has nothing in common with unwanted contamination from GM corn. Gene-flow from GM corn, imposed on farmers without their informed consent, is an entirely undesired outcome offering no benefits for the farmer. They call it “genetic pollution.” It can pose a long-term risk to native landraces. Transgenic traits do not necessarily reveal themselves after contamination. That means farmers can unknowingly spread such contamination from their pollen year after year to other corn plants. 

Mexican researchers discovered such contamination in their 2013 survey of native corn varieties. Biotechnologist Antonio Serratos contributed to that survey, discovering an impressive number of native corn varieties growing in the small plots of agricultural land within the sprawl of Mexico City. While he was encouraged by the corn diversity he found, he reported that some of the native varieties he tested had transgenic traits in their DNA. 

“In Mexican fields, transgenic native maize is being created,” he told me at the time. ”If [GM] maize seeds are sold or exchanged, the contamination will grow exponentially. That is the point of no return.” 

The tribunal’s misguided reasoning has particular importance for indigenous communities that value the integrity of native corn as part of their cultural heritage. In fact, Mexico argued in the dispute with the U.S. that respect for indigenous cultural rights, guaranteed in the USMCA, should include protection from contamination of both crops and foods. The panel gave itself a pass on that one as well, ruling that if Mexico wasn’t going to protect native corn from hybrids its measures would not serve to protect native corn from GMOs. 

 Seed-sharing under threat

 Calling Mexico’s GM corn restrictions excessive and ineffective in protecting native varieties, the tribunal’s alternative recommendation for controlling such unwanted gene flow was even more misguided. It suggested that “the informal seed exchange practices of indigenous and farming communities” were among the “underlying issues” Mexico should address to prevent contamination. 

Limiting seed-sharing is entirely at odds with the science of seed diversity and evolution, says researcher Erica Hagman, who helped prepare Mexico’s defense in the USMCA dispute. Mexico’s rich corn diversity is the direct result of millennia of adaptive practices by farmers in their fields. That is how Mexico produced the 22,000-plus distinct varieties of native corn identified in the 2013 survey: Farmers saved, exchanged, and experimented with different varieties to create corn better adapted to the local environment and the nutritional and cultural preferences of their communities. The tribunal’s suggestion that Mexico should limit such seed-sharing to prevent GM corn contamination runs completely counter to the practices of in situ conservation of agricultural biodiversity.

“The attempt to limit the free exchange of seeds is dangerous for the processes of constant diversification that indigenous peoples have carried out,” says Erica Hagman. ”The approach also shows a serious lack of commitment to respect and protect human rights, particularly those of indigenous peoples and peasant communities. This is rooted in free trade agreements, which subordinate public to private interests.”

 Mexico’s constitutional ban on GM corn cultivation ensures that such misguided reasoning will not guide public policy. The amendment was strengthened by proposals from civil society that extended the ban to new genetically engineered seeds by banning any crops “produced with techniques that overcome the natural barriers of reproduction or recombination, such as transgenics.” This limits some of the new generations of genetically engineered crops, putting Mexico ahead of Europe in its limits on such technologies.

While the constitutional reform does not include some of the original language restricting GM corn consumption, no doubt in deference to the trade ruling, the final version shows a clear preference for non-GM crops, leaving the door open to tighter regulation.

Ignoring evidence of GM health risks

On the risks of GM corn and its associated herbicides to public health, the panel was equally sloppy, ignoring the reams of scientific evidence Mexico presented in its defense. The tribunal rejected Mexico’s argument that existing risk-assessment procedures failed to meet Mexico’s own standard of zero-tolerance for GM corn in tortillas, given Mexicans’ exponentially higher exposure due to their corn-based diets. 

Far from ruling that Mexico failed to present adequate scientific evidence to justify its policies, the tribunal simply declined to address the disturbing evidence, including links between GM corn varieties, particularly insecticidal Bt corn, and a range of health effects including effects on male fertility, immunological alterations, kidney and liver toxicity, and damage to the digestive system, liver and pancreas. Also among the ignored evidence – residues from glyphosate-based herbicides remain in substantial quantities on GM corn and other food crops, and studies link higher exposure to glyphosate in early life to cancer, adverse early neurodevelopment, lower birth weight, and reproductive birth effects – effects that also show up in lab animals exposed to glyphosate.

It is no wonder the Mexican government proceeded with its constitutional amendment to ban the cultivation of GM corn. This is “a major step forward for the defense of native corn varieties, the health of the Mexican population, and the protection of Mexico’s biocultural heritage associated with corn,” said Tania Monserrat Téllez from the Sin Maíz No Hay País coalition.

While Mexico chose to comply with the flawed USMCA ruling, there is little evidence that Mexicans will stop fighting to keep GM corn out of their tortillas. 

Recent polls showed that more than 80% of Mexicans want tortillas free of GM corn. A new mill is now open, dedicated to handling only non-GM corn, and the government is redoubling efforts to increase domestic production of non-GM corn for the sector. The original presidential decree still calls for the phaseout of glyphosate-based herbicides and mandates procedures for tracking GM corn coming into Mexico.

A “Right to Food” law passed last year calls for labeling all foods that contain GM ingredients. That process could take time to implement, but don’t be surprised if consumer and tortilla industry groups act sooner to agree on a voluntary label for GM-free tortillas. 

 It’s time to give Mexicans what they want: GM-free fields and tortillas, and food sovereignty.

(Timothy A. Wiseis the author of Eating Tomorrow: Agribusiness, Family Farmers, and the Battle for the Future of Food (New Press 2019) and a researcher at Tufts University’s Global Development and Environment Institute.)

(Opinion columns published in The New Lede represent the views of the individual(s) authoring the columns and not necessarily the perspectives of TNL editors.)