Mexico-US Deadlock over Mexico’s Restrictions on GM maize

TWN Info Service on Biosafety
27 April 2023
Third World Network

Dear Friends and Colleagues

Mexico-US Deadlock over Mexico’s Restrictions on GM maize

In December 2020, Mexican President Andrés Manuel López Obrador issued an executive order that directed the government to “revoke and refrain from granting authorizations” for the use of GM maize in Mexican diets and for “release into the environment” and to phase out glyphosate by January 2024 (Item 1). Mexico is a centre of origin and diversity of maize, with maize central to the identity and culture of its Indigenous Peoples.

In January 2023, the U.S. demanded that Mexico provide scientific evidence to justify what the U.S. government claims are illegal trade restrictions under the U.S.-Canada-Mexico trade agreement (USMCA). In response, Mexico released a revised decree on 13 February, clarifying that any restrictions on GM feed maize, which is the overwhelming majority of U.S. exports, would only be implemented gradually, pending a full review of the science and the availability of adequate supplies of non-GM maize (Item 2). The U.S. government nevertheless filed a formal complaint on March 6 against Mexico.

The revised decree reiterates the immediate ban on the cultivation of GM maize. The revisions clarify that there is no ban on the importation of U.S. GM white maize, but there is an immediate prohibition on the use of any GM maize in products for “direct human consumption,” clearly defined as the tortilla and maize flour supply chain, but not on livestock feed or industrial uses.

The new decree makes clear that Mexico reserves the right to take precautionary measures it considers important to protect public health and the environment, including the genetic integrity of its rich diversity of native maize.

Mexico’s highest government science body has provided a database on glyphosate and GM maize showing that there are documented health risks from exposure to glyphosate, and there is sufficient evidence of the potential health risks associated with consuming large quantities of minimally processed GM maize, which may also contain glyphosate residues. These justify Mexico’s precautionary policies (Item 3).

Furthermore, there is nothing in the USMCA that obligates a country to approve a GM crop approved in another country. Nor does it mandate that the three countries must accept other countries’ scientific assessments nor calculations of risk. Importantly, the Mexican government is not restricting imports, but restricting the use of GM maize in only one defined set of food products.


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Item 1


By Lisa Held
Civil Eats
23 Feb 2023

In Mexico, a coalition of Indigenous, farm, and environmental advocacy groups have been working for decades to safeguard the genetic diversity of the crop that is a cornerstone of both their diets and their cultural and ecological heritage: corn.

Just two years ago, they celebrated a major victory, when President Andrés Manuel López Obrador issued the first executive order that directed the government to “revoke and refrain from granting authorizations” for the use of genetically modified (GM) corn in Mexican diets and for “release into the environment” by January 2024. While growing GM corn in Mexico has not been allowed for 25 years, millions of tons of the corn enter the country each year via imports. The order also called for a complete phaseout of the controversial herbicide glyphosate by that date.

“With the aim of achieving self-sufficiency and food sovereignty, our country should aim to establish sustainable and culturally appropriate agricultural production, through the use of agroecological practices and inputs that are safe for human health, the country’s biocultural diversity, and the environment, as well as congruent with the agricultural traditions of Mexico,” López Obrador wrote in the order.

Now, however, in the face of U.S. pressure, Mexico is weakening the ban, which was in part intended to prevent genetically modified seed from contaminating native varieties.

Because the executive order was short on specifics, it was unclear from the start what it would mean for the 17 million tons of mostly GM corn exported to Mexico from the U.S. every year—used primarily for livestock feed. And since last fall, U.S. officials, including Secretary of Agriculture Tom Vilsack, have been meeting with Mexican officials to advocate for its reversal.

Vilsack and others said the recent order violated the free trade agreement between the U.S. and Mexico, a fact that some analyses of the agreement’s language dispute. As officials negotiated, preliminary reports suggested López Obrador’s government would stick to including corn used for livestock feed but delay the start date of the ban to 2025 to alleviate U.S. concerns.

Then, at the end of January, the U.S. agriculture trade chief demanded Mexican officials provide scientific evidence to support the bans on both GM corn and glyphosate by February 14. And finally, last week, the Mexican government issued an order that came with new clarifications. Officials said the ban on GM corn would still apply to corn used in flour, dough, or tortillas but not to livestock feed or industrial uses.

“It leaves the door open to GM corn coming from the U.S., and that, from our perspective, still poses a risk,” said Gustavo Ampugnani, the executive director of Greenpeace Mexico, in an interview with Civil Eats.

Advocates worry that because the grain itself is a seed, those seeds will end up getting planted somewhere. Then the GM varieties, which are bred for traits including resistance to glyphosate and to include a protein that kills certain insects, will cross-pollinate with native corn varieties, called landraces.

“It’s not just hypothetical,” Ampugnani said, pointing to research from the early 2000s that found transgenic DNA in corn plants grown in Oaxaca. “The only explanation for this to happen was that the grain that we were importing from the U.S. was being used as seeds.” Past reports have shown those imported seeds can be viable, even when intended for use as feed.

Ampugnani and advocates from the many organizations he works with say that protecting the country’s native landraces is especially critical right now, given that economic, environmental, and other pressures on small- and medium-sized corn growers could lead to them abandoning farming.

“The ancient cultures who were living in Mexico and Central America domesticated the corn in such a way that you can find corn for very specific temperatures, soils, and altitudes in Mexico. So, we are talking about biodiversity. We are talking about plant diversity, but a special plant which is used for food as well,” he said. “So, from this ecological point of view, Mexico has to do as much as possible to protect these landraces from being contaminated with GE varieties.”

Critics of López Obrador’s ban say Mexico needs the corn imports to feed its citizens and keep the economy humming and that there is no evidence that shows GM corn is detrimental to the environment or human health. One 2004 commission focused on GM corn and biodiversity found clear evidence that transgenic DNA had been imported in U.S. corn—and that those genes were already present in and would continue to cross-contaminate Mexican landraces. But the commission also found that the introduction “of a few individual transgenes is unlikely to have any major biological effect on genetic diversity in maize landraces.”

Interestingly, in his original order phasing out GM corn, López Obrador cited reliance on the “precautionary principle” as a key component of international biodiversity treaties that “have determined that the authorities observe said principle to prevent serious or irreversible damage.” That principle basically holds that when evidence of harm is not conclusive, it’s better to be safe than sorry. But U.S. policy on genetic engineering and pesticide use tends to follow an opposite rule.

If the evidence of a crop or chemical’s harm is not bulletproof, agencies tend to allow its use until harm is sufficiently documented. With genetics and biodiversity, that approach could be especially risky, since the same 2004 commission found that “removing transgenes that have introgressed widely into landraces is likely to be very difficult and may in fact be impossible.”

As the issue has continued to percolate, anti-GM advocacy organizations across the U.S., Mexico, and Canada have joined forces to protest the Biden administration’s stance and support Mexico’s original order. Groups in the U.S. have called the American stance “21st century imperialism” and pointed to an economic opportunity for U.S. farmers to respond to demand for non-GM corn.

On the ground in Mexico, Ampugnani said that their coalition was digesting the latest development and would be ready to come together to figure out their next steps next week.

“Right now, while we have authorities that are more like-minded, this is our opportunity to make it better,” he said.


Item 2


By Timothy A. Wise
Food Tank
Feb 2023 

U.S. efforts to bully Mexico over its announced restrictions on imports of genetically-modified (GM) corn intensified last week, as a U.S. Trade Representative official gave the Mexican government less than a week “to explain the science behind Mexico’s planned bans on genetically modified corn and glyphosate herbicide,” according to Reuters.

In response, Mexico’s Minister of the Economy, Raquel Buenrostro, announced that the government is indeed revising its original December 2020 presidential decree to clarify the nature and scope of the restrictions, originally announced to take effect in January 2024. Sure enough, her ministry released the revised decree February 13. The new edict addresses many U.S. concerns, most importantly clarifying that any ban on GM feed corn, which is the overwhelming majority of U.S. exports, would only be implemented gradually, pending a full review of the science and the availability of adequate supplies of non-GM corn.

Don’t expect any thank-you notes from U.S. officials. Indeed, U.S. Agriculture Secretary Tom Vilsack was quick to snap the olive branch offered by Mexico. “USDA is disappointed in Mexico’s new decree regarding genetically modified corn.” Trade officials told Inside US Trade that USTR does not consider the decree a “formal response” to its questions on the science.

So fasten your seatbelts for another bumpy ride through the highly polarized debates over what constitutes “sound science” and over what levels of precaution governments should be allowed to take in the face of scientific uncertainty. To U.S. industry and government officials, precaution is a dirty word.

As a public service, I offer here some of the scientific evidence justifying Mexico’s restrictions on GM corn and glyphosate. It is a small sample from a large and still-growing literature.

GM Corn restrictions are intended to promote the health of people and the climate.

Mexico’s proposed GM corn restrictions are part of a larger effort by the government of Andrés Manuel López Obrador, swept into power in a 2018 landslide, to better protect public health and the environment. The three-year phaseout of glyphosate, the herbicide in Bayer/Monsanto’s Roundup products, is just one of a range of toxic pesticides being banned as part of a sweeping public health law now making its way through the legislature. The glyphosate phaseout is reiterated in the new decree with a deadline of March 2024, and usage has declined steadily in the last two years. The government has also taken bold action to address Mexico’s alarming rise in obesity and non-communicable diet-related diseases, enacting a strong labeling requirement for foods high in salt, fats, and sugars.

Environmental initiatives include the promotion of agroforestry and agroecology and protection of Mexico’s unique diversity of corn varieties from cross-pollination by GM corn. The revised decree, which applies only to corn, not other GM crops does the following:

It reiterates the immediate ban on the cultivation of GM corn to prevent cross-pollination, in line with the court-ordered injunction in place since 2013.

The revisions clarify that there is no ban on the importation of U.S. GM white corn, but there is an immediate prohibition on the use of any GM corn in products for “direct human consumption,” clearly defined as the tortilla and corn flour supply chain. Enforcement will focus on producers of those products, and the decree calls for measures to ensure traceability, an important step.

The decree also reiterates that government agencies will cease all purchases of GM corn and glyphosate.

It eliminates the 2024 deadline for the phaseout of GM corn imports for animal feed and industrial uses, but it keeps in place the intention to substitute domestic non-GM corn over time, which aligns with government plans to increase food self-sufficiency.

It establishes Mexico’s Federal Commission for Protection Against Sanitary Risks (COFEPRIS, by its Spanish acronym) as the agency responsible for assessing risk and approving future import licenses requested by U.S. exporters. Implied in the decree is the right to enforce the government’s preference for non-GMO corn for future uses.

It calls for further study, in conjunction with North American partners, of the risks to human health and the environment from GM feed corn.

The decree commits to science-based decisions in compliance with the United States-Mexico-Canada (USMCA) trade agreement. In Buenrostro’s words, “If they prove that there is no harm to health, then it will be approved.”

And the new decree makes clear that Mexico reserves the right to take precautionary measures it considers important to protect public health and the environment, including the genetic integrity of its rich diversity of native corn.

Science evidence makes the case for precautionary measures.

U.S. industry representatives and government officials have repeatedly insisted that Mexico’s actions are not based on science. As always, U.S. leaders insist that they get to determine what constitutes “sound science,” despite the atrocious record of poor public health protections by U.S. regulations heavily influenced by industry. But Mexico does indeed have science on its side.

In fact, Mexico’s highest government science body has published a database on glyphosate and GM corn with 28 pages of citations. If fact it is so large that it is difficult to navigate. U.S. officials could examine that scientific evidence, which has been available since the 2020 decree. But to make it easier for them, let’s highlight some of the most important evidence.

In the U.S., which has allowed unlabeled GM corn to enter the food supply since the mid-1990s, the mantra is that no one has been harmed, regulators have adequately tested the new products, and there is a scientific consensus on the safety of eating GM foods. Many scientists beg to differ, as I wrote in an earlier Food Tank article, arguing that scientific uncertainty justifies precautionary restrictions because evidence of harm, mainly from animal studies, has not been taken seriously nor been followed up to assess the risks to human health. Below is some of the key evidence.

2015 statement signed by more than 300 scientists insisted that there is no scientific consensus on GMO safety: “the scarcity and contradictory nature of the scientific evidence published to date prevents conclusive claims of safety, or of lack of safety, of GMOs.”

My late Tufts University colleague, Sheldon Krimsky, conducted broad reviews of the academic literature in 2018 and reported “An Illusory Consensus Behind GMO Health Assessment. He found 26 studies that “reported adverse effects or uncertainties of GMOs fed to animals;” eight other literature reviews that showed anything but a consensus on safety; and no consensus among medical and scientific associations. All are listed in his extensive bibliography. (I summarize his findings in this earlier Food Tank article.)

A 2017 peer-reviewed study reported the “Pervasive Presence of Transgenes and Glyphosate in Maize-Derived Food in Mexico,” which raised alarms about the integrity of Mexico’s food supply even when GM corn was not being grown in the country.

Many scientists have also pointed out that evidence from the U.S. experience is of limited value because Mexico’s high levels of direct consumption of minimally processed corn products, such as tortillas, presents levels of risk that make U.S. exposures a poor guide to risk. As expert Charles Benbrook recently told me, “There is inadequate data to conduct an assessment of the impacts of Bt corn on the GI tracts of people consuming corn-based foods. The studies have still not been done.” This is known as “undone science” – investigations not carried out due to vested interests.

While most of the current controversy has focused on concerns about human health, Mexico’s decree also cites the threat to the genetic integrity of the country’s megadiverse native corn due to uncontrolled cross-pollination from GM corn planted in nearby fields. Such risks were the basis for the successful challenge to permits issued by Mexico’s previous administrations for cultivation of GM corn, a citizen lawsuit I document in my excerpted book chapter, “Monsanto Invades Corn’s Garden of Eden in Mexico.

I interviewed many scientists about the risks of “gene flow,” but we can look to NAFTA itself for the definitive science. NAFTA’s own Commission for Environmental Cooperation in 2003 conducted a trinational expert assessment of the risks to native corn biodiversity from GM corn. The scientific findings in “Maize and Biodiversity: The Effects of Transgenic Maize in Mexico” are still relevant today.

Open pollination can result in gene flow to nearby fields of native corn, and the pollen can travel much further than previously believed. (A later study showed transgenes present in native corn varieties in 14 Mexican states).

The contamination that prompted the study likely came from GM corn imported from the United States, unlabeled, distributed as food through a Mexican government agency, then unknowingly planted by a farmer. (That could easily happen again, which is why Mexico’s decree calls for traceability of imported GM corn).

Transgenes can spread further through subsequent pollination, threatening native corn diversity, which is invaluable culturally, environmentally, and also economically for future crop breeding.

Precautionary policies are warranted, including policies to restrict the importation of corn in kernel form from the U.S., which does not identify GM content through labeling.

U.S. trade officials have not directly challenged Mexico’s glyphosate phaseout, but there is no shortage of scientific evidence to justify the ban.

The World Health Organization (WHO) finds that Roundup herbicides are a “probable human carcinogen,” which I covered in an earlier Food Tank article. The WHO findings are summarized in an accessible two-page monograph and in The Lancet Oncology.

According to Forbes, Bayer/Monsanto has settled more than 100,000 lawsuits charging the company with misleading consumers about the safety of Roundup, and another 30,000 lawsuits are pending.

Damaging evidence keeps mounting. One recent study showed negative health impacts downstream from farms heavily using glyphosate, while the Guardian reported that 60 percent of urine samples in the U.S. showed traces of glyphosate and higher levels of “oxidative stress,” which is associated with cancer risk.

As I have previously reported, there is nothing in the new Agricultural Biotechnology section of the USMCA that obligates any country to approve a GM crop approved in another country. Nor does it mandate that the three countries must accept other countries’ scientific assessments nor calculations of risk. It mandates transparency, consultation, and science-based decision-making. That seems to be exactly what the Mexican government is offering the U.S. with its revision of the 2020 presidential decree.

Mexico retains the right to take precautionary measures it deems necessary to protect public health and the environment. Precaution may be a dirty word for U.S. regulators, but not a U.S. public wary of industry lies about the dangers of its products – tobacco, fossil fuels, lead, asbestos, DDT, and PCBs, just to name a few. (See “Late Lessons from Early Warnings” for a longer list of such cases). Rather than challenge Mexico’s health and environmental policies, perhaps we can learn something from them.


Item 3


By Timothy A. Wise
Food Tank,GM%20corn%2C%20which%20may%20also
30 March 2023

Mexican and United States trade officials are meeting this week in Mexico City in the first negotiations since the U.S. government filed a formal complaint March 6 against Mexico’s policies restricting the use of genetically modified (GM) corn and the herbicide glyphosate. Science is at the center of the agenda.

Since December 2020, when Mexican President Andrés Manuel López Obrador first announced the restrictions, U.S. government, industry and commodity groups have demanded that Mexico produce scientific evidence to justify what the U.S. government claims are illegal trade restrictions under the U.S.-Canada-Mexico trade agreement (USMCA).

The United States Trade Representative (USTR) took the action despite a more flexible new decree, issued February 13, which exempts feed corn, the overwhelming majority of U.S. exports, from restrictions. As U.S. Agriculture Secretary Tom Vilsack stated March 6, “we remain firm in our view that Mexico’s current biotechnology trajectory is not grounded in science, which is the foundation of USMCA. We remain unequivocal in our stance that the science around agricultural biotechnology has been settled for decades.”

On March 29, the Mexican government laid out the science in an impressive virtual conference organized by CONACYT, the government’s highest science body. Hopefully, the USTR delegation was watching. The U.S. stance may be unequivocal, but the science is anything but settled. Particularly the science of precaution.

As scientist Alejandro Espinoza Calderón, director of Mexico’s biosecurity agency Cibiogem, explained, “Mexico has a rich store of exceptionally healthy varieties of corn. It is alarming to find that 90 percent of tortillas were shown to have traces of both glyphosate and transgenics. The biosecurity of Mexico is of utmost importance.”

The message from scientific experts on the panel was clear: There are documented health risks from exposure to glyphosate, including in children and even newborns, and there is sufficient evidence of the potential health risks associated with consuming large quantities of minimally processed GM corn, which may also contain glyphosate residues. These justify Mexico’s precautionary policies.

As National University biologist Ana Laura Wegier Briuolo emphasized, “without healthy corn we cannot have healthy people.”

Dr. Omar Arellano, from the university’s Ecology and Natural Resources Department, presented the most recent evidence, from Mexico, Argentina, the United States, and elsewhere, on the mechanisms by which glyphosate impacts human health. “The science is much clearer now than it was twenty years ago,” he reminded the audience.

Dr. Felipe Lozano Kasten, a pediatric doctor and public health professor in the state of Jalisco, reported a long-term study of 677 children that found 98 percent with glyphosate in their urine. Doctors found associated health impacts, including to kidney function. A forthcoming paper reports that 23 percent of babies showed traces of pesticides at birth.

U.S. allegations that Mexico was not basing its policies on science were always a smokescreen. The science agency has for years maintained a public web page with annotated references on studies that document risks of both glyphosate and GM corn consumption, as well as the additional risk to native varieties from cross-pollination by GM corn. The science agency is now planning a series of virtual conferences in May to present the full range of scientific evidence.

As the U.S. government begins formal consultations on its threatened USMCA dispute, it may have an uphill climb. Not only does Mexico have plenty of sound science on its side, but the text of the trade agreement is quite explicit in recognizing each country’s right to regulate in the ways it sees fit.

Even the new agricultural biotechnology section of the updated USMCA is explicit: “This Section does not require a Party to mandate an authorization for a product of agricultural biotechnology to be on the market.”

USTR in its formal complaint claimed violations of the Sanitary and PhytoSanitary (SPS) chapter on health and safety regulations. But Section 4 of that chapter clearly grants Mexico the right to establish its own standards for public health protection:

“This Chapter does not prevent a Party from:

(a) establishing the level of protection it determines to be appropriate;

(b) establishing or maintaining an approval procedure that requires a risk assessment to be conducted before the Party grants a product access to its market; or

(c) adopting or maintaining a sanitary or phytosanitary measure on a provisional basis if relevant scientific evidence is insufficient.”

Such language guarantees sovereign countries the right to regulate in the ways they deem appropriate to protect public health and the environment. It mandates transparency. It does not mandate that Mexico accept U.S. definitions of what constitutes sound science, nor does it proscribe precautionary policies in the face of scientific uncertainty.

The other reason USTR will be hard-pressed to win a USMCA dispute is that there is no meaningful trade restriction and no significant economic harm to U.S. exporters. USTR Katherine Tai, in announcing the call for consultations, said, “Mexico’s policies threaten to disrupt billions of dollars in agricultural trade.” There is no credible evidence to support that claim, which is based on flawed and now wildly outdated industry-funded economic studies.

Mexico’s revised decree is explicit that it now applies only to GM corn used in tortillas and corn-dough, which is supplied overwhelmingly by Mexican producers of white and native corn varieties. Only 4 percent of U.S. corn exports are white corn, and most of that does not go into tortillas.

More important, the Mexican government is not restricting imports, it is restricting the use of GM corn in one defined set of food products. The U.S. government is unlikely to find any significant number of exporters of GM white corn who see their markets reduced by Mexico’s actions.

As Mexican Economy Minister Raquel Buenrostro stated in response to the USTR request for technical consultations, Mexico’s decree is based on science and she will challenge the U.S. government in the consultations to show “quantitatively, with numbers, something that has not occurred: that the corn decree has commercially affected” U.S. exporters.

The Mexican government will show what has occurred: Its cherished tortillas are being contaminated with glyphosate and GM corn. And they intend to put a stop to that.

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