A few stray wheat plants discovered in Oregon have turned out to be a genetically-modified strain that was developed by Monsanto in the 1990s, but was never approved for human consumption. The renegade plants could imperil billions of dollars worth of US wheat exports—but what exactly happened, and what does it mean?

The discovery

Last month an Oregon farmer sprayed one of his fields with Roundup weed killer, only to find that several wheat plants survived the cull. When the US Department of Agriculture investigated, it found out why: the plants were an unapproved genetically modified strain made by the biotech giant Monsanto. So-called “Roundup Ready” modifications allow farmers to apply much higher levels of pesticides without harming crops, and are common in soy and corn—but those crops are mostly used for animal feed. No GM wheat is currently approved for sale or production in the US, or anywhere else in the world.

Monsanto was authorized to test their GM wheat from 1998 to 2005 in 16 US states. It did, but decided to scrap the variety because there wasn’t much of a market. The crop never received final approval.

The problem

The wheat is not probably not harmful to humans—although since testing was never completed, we can’t be sure. Nevertheless, most of Asia (not to mention Europe and a certain portion of the United States) is firmly opposed to GM crops made for human consumption. Asia consumers around 40 million tonnes of wheat a year—about a third of the global total—and much of it comes from the US, the world’s biggest exporter.

The reality of GM testing a product in open fields is that it’s quite easy for cross-contamination. It’s like the dinosaurs in “Jurassic Park”—no matter how well-designed the safeguards, life always finds a way to jump the fence. Doug Gurian-Sherman, a scientist with the Union of Concerned Scientists in Washington, told Bloomberg Businessweek he “wouldn’t be at all surprised if there are a number of experimental genes that have contaminated and are happily being passed along at low levels in the food supplies of various crops already, but nobody’s testing. It’s really a ‘don’t look, don’t tell’ situation. We just really don’t know.”

The fallout

Japan has already cancelled its imports of some types of US wheat including white grains and animal feed. China, South Korea and the Philippines have all said that they are monitoring the ongoing US investigation, and the European Union said it was stepping up testing. China, which is expected to need much more imported wheat in the coming years, is expected to import 3.5 million tonnes in the year to June 2014. The Philippines imports around 4 million tonnes each year, according to Reuters.

But the damage to US exports is only likely to go so far. As the biggest exporter of wheat (around a fifth of global supplies), the US is indispensable for wheat importers, particularly in Asia where the climate is not particularly well-suited to the crop.

But for Monsanto, it could be extremely expensive. A similar case in 2006 involving a GM rice strain made by Bayer CropScience cost the company $750 million in payments to growers after Japan slapped a ban on rice imports (it has since been lifted). The company is unpopular anyway, as recent protests testify.

In a statement on Wednesday, Monstanto pointed out that each year around 58 million acres of wheat are planted in the US, arguing that the reaction to a few plants in Oregon is a bit over the top. Whether or not that’s true, it has some difficult questions to answer.