For the last four years, Nebraska organic farmer David Vetter has been testing his corn for a new kind of pollution. Situated right in the middle of corn country, Vetter's 280-acre farm is small compared to those of his neighbors. All around him are farmers growing genetically modified corn. And that poses a problem. Corn is an open-pollinating crop. Wind and insects can carry pollen from a few yards to several miles.

Last year, Vetter's organic corn tested positive for genetic contamination. "We've been letting customers who buy in bulk know the situation," says Vetter. "Right now, most of it is still sitting in storage on the farm."

Susan Fitzgerald and her husband operate a 1,300-acre farm outside Hancock, Minnesota. Last year, Fitzgerald's 100 acres of organic corn showed evidence of genetic contamination, as did her neighbor's organic corn crop. The pollen had traveled more than 120 feet from another neighbor's farm. Instead of selling her organic corn for approximately $4 a bushel, she had to sell her crop on the open market for $1.67.

Vetter and the Fitzgeralds are not alone. Organic farmers are having an increasingly difficult time preventing genetically modified organisms (GMOs) from migrating into their fields. And organic food companies are struggling to ensure the integrity of their products. For consumers who demand organic foods, the alarm bells are ringing.

In April, The Wall Street Journal tested twenty food products labeled "GMO free" and found that sixteen of them contained at least traces of genetically modified ingredients; five had significant amounts. One of the companies testing positive, albeit with trace amounts, was Nature's Path Foods, the largest organic cereal company in the world.

"We have found traces in corn that has been grown organically for ten to fifteen years," Arran Stephens, president of Nature's Path Foods, told The New York Times in June. "There's no wall high enough to keep that stuff contained."

Biotechnology, utilized primarily on large industrialized farms, splices genes from other plant and animal species into seeds to produce a variety of desired traits, including the ability to withstand exposure to pesticides and even to produce their own pesticides. The most popular genetically modified crops grown in the United States are soybeans, corn, cotton, and canola. Approximately 68 percent of all soybeans and 26 percent of all corn is genetically engineered in the United States, according to June statistics from the U.S. Department of Agriculture.

But this is counting only those crops that are designed by genetic engineering, not those that are contaminated by it.

How much contamination is taking place on organic fields is an unanswered question.

"For certain crops, it is absolutely pervasive," says David Gould, an organic certification specialist. "Virtually all of the seed corn in this country has at least a trace of GMO contamination and often more. Canola is as bad if not worse. Soy is very problematic, too."

Other crops may also pose risks. Squashes, sugar beets, tomatoes, and potatoes have been approved for bioengineering. "These are not wide-spread yet," says Gould. "Just give them time, and they'll be a problem, too."

Organic Trade Association Executive Director Katherine D'Matteo says there is some misunderstanding about what organic products are. "We've built the expectation that there is a purity in the world, and even the slightest contamination is a disaster," she says.

"We're seeing traces appearing somewhat more frequently in organic, but we're not seeing an escalation to high percentages," says John Fagan, CEO of Genetic ID, a firm that tests food for many organic and conventional food companies. "If you compare organic with conventional, it is orders of magnitude cleaner."

Genetic contamination can come through the sharing of equipment like combines, elevators, or trucks. And it can also come through seeds. "It is very difficult to find clean seed," says Gould. "Without good seed, we will never be able to produce clean crops."

Jim Riddle, Secretary of the National Organic Standards Board (NOSB), encourages farmers to test all organic seeds to ensure they are free of genetically modified ingredients before planting. Thus far, most organic seeds have not tested positive for this type of contamination. But the American Seed Trade Association recently asked the U.S. Department of Agriculture to establish a tolerance level of 1 percent genetic contamination for seed that is labeled nonmodified.

"It is a pretty good clue that the seed companies can't manage what they are doing when they ask for a tolerance level," says Vetter. "They've come right out and admitted that they can't guarantee non-GMO seed."

The costs associated with trying to keep organic separated from genetically modified seed are mounting. For farmers, it includes buffer zones, cleaning equipment, inspections of crops and processing facilities, and frequent testing. Seed testing costs on average about $10 a bag. After-harvest testing can cost $400 per sample.

"A real issue at the moment for organic farmers is the increased cost associated with testing," says Bob Scowcroft, with the Organic Farm Research Foundation. "If you're sharing equipment, does the neighbor have to steam clean his combine? What about the truck and elevator if it's multi-use?"

A few years ago, there was little incentive for organic farmers to try to find out whether or not their crops were tainted by genetically modified organisms. Why risk the monetary loss that could result if you discovered your crop was contaminated? But now, most organic farmers are doing some type of testing.

"Your buyers are going to find out," says Vetter. "So farmers are going to have to test."

Another major concern is the potential for the loss of certification that allows farmers to sell their products as "organic." If an organic crop tests positive, a certifier has to make a judgment call, taking into account the extent of contamination and the farmer's efforts to stop it. The official could pull the farm's certification, or more likely pull organic certification for the contaminated crop, says Riddle, whose board is appointed by the USDA to oversee the implementation of national organic rules.

"I do think the NOSB needs to look at the threshold or rejection level issue," says Riddle. "Organic does not mean chemical free or GMO-free, but it means GMOs are not used in the production. Organic farmers are being penalized by the actions of their neighbors. The tolerance level should be very low."

While the United States does not have set tolerance levels for organic food, there are some relevant standards in other countries. In Europe, any food with a content of 1 percent or higher of genetically modified ingredients must be labeled as such. In Japan, the rule is 5 percent or higher. In an effort to avoid the labeling requirement, food companies in Japan and Europe are rejecting crops that exceed these thresholds. According to Fagan of Genetic ID, organic companies in Europe and Japan are strict about genetically altered content, with most companies unwilling to accept anything with a 0.1 percent threshold or higher.

Organic food grown in the United States is fast becoming a major export. According to the Organic Trade Association, the United States exports more than $40 million in organic goods to the United Kingdom and an estimated $40 to $60 million to Japan each year. The association estimates that U.S. organic exports to Europe are growing by 15 percent per year, and by 30 to 50 percent per year to Japan.

Most other countries expect that organic products coming from the United States will be free of genetically modified ingredients. But that situation could change. In 1999, Europe rejected corn chips manufactured by the Wisconsin company Terra Prima because of genetic contamination. The event cost the company hundreds of thousands of dollars.

Organic is the fastest expanding sector of the domestic food business--growing a whopping 20 percent every year since 1990. There are 7,800 certified organic farms in the United States, up from 6,600 in 1999, according to the Organic Farm Research Foundation. Organic sales will likely increase from an estimated $5.4 billion in 1998 to more than $9 billion in 2001, according to Datamonitor, the food industry analyst.

Organic foods are popular with consumers who prefer natural ingredients and worry about the health hazards of pesticides, synthetic hormones, and other aspects of industrial agriculture.

But if consumers cannot be assured that they are getting organic products free of genetically modified ingredients, the market may diminish.

In 1997, when the U.S. Department of Agriculture proposed national standards that would have considered genetically modified crops to be organic, nearly 300,000 people submitted comments denouncing the plan. A major selling point of organic foods has been that the standard disallows genetically modified organisms. Many organic food companies, like Nature's Path, Eden Foods, Erewhon, and Gardenburger, tout this claim on their labels.

Last December, the organic community roundly hailed the conclusion of a tortuous ten-year process to develop national standards for organic food production. While the final standard explicitly excluded genetically modified crops, it was decidedly vague on the issue of contamination. The rules appear to allow some genetic impurities, although they do not specify how much. The rules state, "The presence of a detectable residue of a product of excluded methods [like genetic alterations] alone does not necessarily constitute a violation of this regulation. . . . The unintentional presence of the products should not affect the status of an organic product or operation."

Because of difficulties in ensuring that food is free of genetically modified ingredients, the Food and Drug Administration's new regulations on genetically modified organisms, announced in January, do not allow companies to claim that their products are "GMO-free." Instead, labels will have to say that the food was not produced through bioengineering.

The demand for crops that have not been genetically modified has increased dramatically since an unapproved yellow corn called StarLink was found in a taco shell last year. StarLink, which is genetically engineered to contain the pesticide Bt in every cell, had been approved for animal feed but not for human consumption because of concerns about dangerous allergic reactions. StarLink has since been found in nearly 300 consumer products, and the EPA estimates it will take up to four years before StarLink is completely out of the food system.

"StarLink has made a big difference in terms of understanding how farm contamination can happen," says D'Matteo. "And it showed how the government didn't have controls in place."

In June, StarLink was found in white corn tortilla chips in Florida, according to The Washington Post. "The presence of StarLink in a white corn product illustrates how difficult it is to keep genetically modified crops from spreading," reported the Post on July 4. "White corn is grown and distributed separately from yellow corn, and industry observers said there are no genetically modified varieties. But they also said it has proven impossible to prevent some commingling of conventional and modified, as well as white and yellow, corn. The mixing, they said, could happen at processing plants, during transportation, and during cross-pollination in fields."

On July 27, the U.S. Environmental Protection Agency announced that it would not establish a tolerance level for StarLink in human foods. This move, opposed by the food industry, effectively bans StarLink from U.S. grocery shelves and mandates testing of corn entering the food supply.

Organic farmers are fighting back. Many family farm groups throughout the country are interested in pushing for legislation that would clearly identify the seed maker, rather than the farmer, as liable for contamination.

Politicians have introduced bills in the U.S. Congress and more than a dozen states that would require labeling of genetically modified foods and stronger pre-market safety testing requirements. Some of the bills would assign liability to seed companies for damages.

"The consumers' right to know what is in the food they eat and how it is made must be protected. The FDA is much too busy protecting the profits of the biotech food companies," says Representative Dennis Kucinich, Democrat of Ohio.

The Maine legislature passed a bill in May that would require manufacturers or seed dealers of genetically engineered plants, plant parts, or seeds to provide written instructions to all growers on how to plant, grow, and harvest the crops to minimize potential cross-contamination. The Maine bill is the first of its kind in the country.

But the future integrity of organic products may well be decided in the courtroom. There is no case law related to genetically altered crops, and no laws have passed (although several have been introduced at the state and federal level) assigning liability. In the past, U.S. courts have ruled against pesticide companies for pesticide drift. Farmers hope they would do the same for genetic drift.

Organic farmers also have been active in lawsuits against the Environmental Protection Agency. One suit, filed in October 1999, demands that the EPA withdraw all genetically modified Bt crops, including StarLink.

Genetically modified Bt crops insert an engineered version of a natural soil bacterium, known as bacillus thurengensis (Bt), into the crop. Organic farmers sometimes used Bt in spray form as a last option to deal with certain pests like the corn borer. But many in the scientific community, and the EPA itself, fear that genetically modified Bt crops will speed up resistance to Bt, thereby rendering the natural spray that organic farmers use ineffective.

A class action lawsuit filed by farmers who did not grow StarLink seeks compensation for lost export markets associated with the scandal. The lawsuit, filed last December, alleges that StarLink's manufacturer, Aventis, failed to follow the EPA registration for StarLink corn and neglected to take other precautions to prevent StarLink corn from entering the human food supply chain. As a result, the suit claims, there has been widespread contamination of the U.S. corn crop with StarLink, which has in turn resulted in a loss of export and domestic markets for U.S. corn and a depression in U.S. corn prices. The suit, filed in Illinois, seeks compensatory and punitive damages, as well as injunctive relief requiring Aventis to decontaminate all soil, farming equipment, storage equipment, harvest equipment, transportation facilities, grain elevators, and non-StarLink seed supplies to prevent further contamination.

Another lawsuit, this one against Monsanto, charges, among other things, that the company failed to test genetically modified seeds and crops adequately before releasing them into the food supply. The lawsuit, filed on behalf of farmers by the Washington, D.C., law firm Cohen, Milstein, Hausfeld, & Toll, also charges that Monsanto, together with other companies, formed a global cartel to fix prices on genetically modified seeds and conspired to restrain trade in the GMO corn and soybean market.

Monsanto disputes that the seeds haven't been adequately tested. "This action is another in a series of unsuccessful attempts by veteran antagonists to stop a technology with the potential to improve our environment, increase food production, and improve health," said David Snively, assistant general counsel for Monsanto. "We're confident this suit will be dismissed."

The courts won't necessarily work to the advantage of the organic farmers. Many in the organic community are still talking about the Percy Schmeiser case, decided earlier this year in Canada. Monsanto sued Schmeiser for growing Roundup Ready Canola. Schmeiser claimed that he had not purchased the seed and that pollen had drifted from a neighbor's farm. The Canadian court ruled that it didn't matter whether the material drifted or not. Schmeiser, it said, was infringing on Monsanto's patent rights. The court ordered him to pay $105,000 to Monsanto.

"If U.S. courts allowed biotech companies to sue organic farmers for selling their contaminated crops, organic farmers could be found liable to pay damages to the contaminating companies. In essence, this would amount to requiring organic farmers to pay for the nuisance caused by these biotech companies," wrote San Francisco attorneys Robert Uram and Giselle Vigneron in a recent analysis of the case.

Farmers like Vetter and the Fitzgeralds are going to extraordinary measures to prevent the contamination of their crops. The Fitzgeralds have planted mostly wheat and soybeans, and have tried to use buffers when their neighbors planted genetically modified corn.

Vetter tried to stagger his planting time with his neighbors'. "Because we knew the chances of cross-pollination were great, we tried to offset planting dates with our neighbors," Vetter says. "We hoped that they would plant early, and we waited as long as we could to plant."

Susan Fitzgerald hopes that organic farmers can work together with conventional farmers interested in planting crops that have not been genetically altered.

"We don't want to make enemies," she says. "But we want to defend our right to grow GMO-free crops."

Ben Lilliston is the communications coordinator of the Institute for Agriculture and Trade Policy in Minneapolis. He is the co-author, along with Ronnie Cummins, of "Genetically Engineered Foods: A Self-Defense Guide for Consumers" (Marlowe & Company, 2000).