A Nov. 10 article on genetically modified corn incorrectly described federal agencies' review of genetically modified crops. The Food and Drug Administration and the Agriculture Department review all applications for food and feed products, while the Environmental Protection Agency reviews only some applications. (Published 11/11/04)

A scientific panel of international experts has concluded that the unintended spread of U.S. genetically modified corn in Mexico -- where the species originated and modified plants are not allowed -- poses a potential threat that should be limited or stopped. But the United States yesterday attacked the report and its conclusions as unscientific, and made clear it did not intend to accept the recommendations.

The report, written by a group convened under the North American Free Trade Agreement, rejected the U.S. position that the modified corn is, in effect, no different than conventionally bred corn hybrids. It said that because the Mexican government has never examined or approved the use of transgenic crops, their presence in the country is an inherent problem.

"How would Americans feel if we started getting living transgenic seeds that had been judged to be safe by the Cuban government but not the American government?" asked Norman C. Ellstrand, a University of California at Riverside geneticist and member of the NAFTA-appointed panel. "We would be outraged, and so are many Mexicans. Like us, they have the right to make up their own minds about genetically modified crops."

The Mexican government embraced the NAFTA report and said it expected to implement many of its recommendations.

The report, only the fifth in the treaty organization's history, was requested by Mexican farmers and officials in 2002 after researchers found that some forms of genetically modified corn were present in Mexico and were being naturally spread by cross-pollination. One variety contained genetically modified bacteria that protect the plant from certain insects, and another protects the plant if a particular kind of otherwise deadly weed killer is used on the fields.

Although it remains uncertain how the modified corn got into Mexican fields, the report concluded that the large-scale importation of U.S. corn was the likely cause. The Mexican government distributes massive amounts of U.S. corn for grinding into cornmeal and flour, but some farmers are believed to have planted the corn instead. Once planted, the genetically modified corn spread naturally in fields over the seasons.

Genetically modified corn can be legally used as food in Mexico but cannot be planted and grown, except in small test plots recently approved by the government.

The NAFTA report concluded that the modified corn does not pose a health risk, but it did say that the environmental consequences are less well understood. It also raised the possibility of the spread of potentially more hazardous types of modified corn -- such as varieties grown in the United States to produce pharmaceuticals and industrial products.

"If those types of corn ever made it to Mexico and got planted, then yes, there would be a health and safety problem that would be very hard to solve," Ellstrand said.

The U.S. rejection of the NAFTA report was broad and pointed.

"This report is fundamentally flawed and unscientific; key recommendations are not based on sound science and are contradicted by the report's own scientific findings," the Environmental Protection Agency and the U.S. Trade Representative said in a joint statement. "Implementing many of the report's recommendations would cause economic harm to farmers and consumers of all NAFTA countries and restrict international trade."

The U.S. statement specifically criticized one recommendation -- that all U.S. corn coming into Mexico be milled at or near the border so it cannot be planted. That practice, it says, "would increase the cost of U.S. corn significantly, negatively affecting Mexico's livestock producers and consumers."

The NAFTA report and the U.S. response are also far apart on what constitutes a scientific assessment of the issue. The report included information about the attitudes of Mexican farmers to the genetically modified corn, saying many find it frightening and a threat to their staple food, while American officials said those views have no place in a scientific study.

In support of their formal critique, the U.S. agencies cited the report's conclusion that "scientific investigations and analyses over the past 25 years have shown that the process of transferring a gene from one organism to another does not pose any intrinsic threat over the short or long term, either to health, biodiversity or the environment."

The NAFTA report went on, however, to conclude that the specific characteristics of any newly created organism need to be examined -- making the case that the benefits and dangers of any genetically modified plant can be determined only by testing in the locales where it will be used. In the United States, the EPA, the Agriculture Department and sometimes the Food and Drug Administration must approve genetically modified plants before they can be introduced.

The National Corn Growers Association also sharply criticized the panel's conclusions. "The report needlessly raises concerns where there are none about a technology that is proven safe and already greatly benefits the environment and farmers around the world," NCGA President Leon Corzine said.

A copy of the NAFTA report was leaked last month to the environmental group Greenpeace, which distributed it in Mexico. The report was released Monday.

After the initial release, Mexico's equivalent of the EPA, Semarnat, said in a statement: "There is no doubt that the recommendations in the official document will be beneficial for Mexico and its environment. . . . Semarnat is awaiting the official publication of this report and is confident that the majority of the recommendations made will be implemented."