European Union environmental officials have determined that two kinds of genetically modified corn could harm butterflies, affect food chains and disturb life in rivers and streams, and they have proposed a ban on the sale of the seeds, which are made by DuPont Pioneer, Dow Agrosciences and Syngenta.
A study says exposure to the corn can affect the larvae of the monarch butterfly.
A protest in August against genetically modified crops in France. The modified corn that would be banned has been grown in America for years.
The preliminary decisions are circulating within the European Commission, which has the final say. Some officials there are skeptical of a ban that would upset the powerful biotechnology industry and could exacerbate tensions with important trading partners like the United States. The seeds are not available on the European market for cultivation.
In the decisions, the environment commissioner, Stavros Dimas, contends that the genetically modified corn, or maize could affect certain butterfly species, specifically the monarch, and other beneficial insects. For instance, research this year indicates that larvae of the monarch butterfly exposed to the genetically modified corn “behave differently than other larvae.”
In the decision concerning the corn seeds produced by Dow and Pioneer, Mr. Dimas calls “potential damage on the environment irreversible.” In the decision on Syngenta’s corn, he says that “the level of risk generated by the cultivation of this product for the environment is unacceptable.”
A decision by the European Union to bar cultivation of the genetically modified crops would be the first of its kind in the trade bloc, and would intensify the continuing battle over genetically modified corn.
Since 1998, the commission has not approved any applications for the cultivation of genetically modified crops, but it has not actively rejected any applications, either, as would be the case with the genetically modified corn products.
Banning the applications for corn crops also would mark a bold new step for European environmental authorities, who are already aggressively pursuing regulations on emissions from cars and aircraft, setting it at odds with the United States and angering industries.
“These products have been grown in the U.S. and other countries for years,” said Stephen Norton, a spokesman for the United States trade representative. “We are not aware of any other case when a product has been rejected after having been reviewed and determined safe” by European food safety authorities, he said.
In 2005, the European Food Safety Authority, a European agency based in Parma, Italy, that operates independently of the European Union, ruled that the products were unlikely to harm human and animal health or the environment. But in the draft decision, Mr. Dimas said that other studies had since come to light on the potential effects of the seeds and that further investigation was needed.
Barbara Helfferich, a spokeswoman for Mr. Dimas, declined to comment on the specifics of the procedure because commissioners had not yet made a final decision. But she said that the European Union was within its rights to make decisions based on the “precautionary principle” even when scientists had found no definitive evidence proving products can cause harm.
“The commission has the authority to be a risk manager when it comes to the safety and science of genetically modified crops,” Ms. Helfferich said.
She said that the decisions by Mr. Dimas could go before the commission within a few weeks, but she said that no date had been set.
In the decisions, Mr. Dimas cited recent research showing that consumption of genetically modified “corn byproducts reduced growth and increased mortality of nontarget stream insects” and that these insects “are important prey for aquatic and riparian predators” and that this could have “unexpected ecosystem-scale consequences.”
Although still preliminary, his decisions could drastically tilt the policy against future approvals of genetically modified crops, said Nathalie Moll, a spokeswoman for Europabio, an industry group with 80 members including Syngenta, Pioneer and Dow.
The decisions “would be setting a precedent for E.U. officials to reject products based on nonverified scientific data,” Ms. Moll said.
Europabio says that the crops grown using the genetically modified corn are already imported into several European countries, including France and Germany, where they are used to feed animals like cows and chickens.
Rob Gianfranceschi, spokesman at the United States mission to the European Union in Brussels, said it was too early to comment on a decision that had not yet been formalized. But he made clear that the United States remained frustrated with European policies on genetically modified crops.
“The United States has consistently stated that the E.U. continues to lack a predictable, workable process for approving these products in a way that reflects scientific rather than political factors,” Mr. Gianfranceschi said.