When you buy a gallon of organic milk, you expect to get tasty milk from happy cows who haven't been subjected to antibiotics, hormones or pesticides. But you might also unknowingly be getting genetically modified cattle feed. Albert Straus, owner of the Straus Family Creamery ... decided to test the feed that he gives his 1,600 cows last year and was alarmed to find that nearly 6% of the organic corn feed he received from suppliers was contaminated" by genetically modified (GM) organisms. Organic food is, by definition, supposed to be free of genetically modified material. But as GM crops become more prevalent, there is little that an organic farmer can do to prevent a speck of GM pollen or a stray GM seed from being blown by the wind onto his land. In 2006, GM crops accounted for 61% of all the corn planted in the U.S. and 89% of all the soybeans. So Straus and five other natural food producers, including industry leader Whole Foods, announced last week that they would seek a new certification for their products, "non-GMO verified," in the hopes that it will become a voluntary industry standard for GM-free goods. In a few weeks, Straus expects to become the first food manufacturer in the country to carry the label in addition to his "organic" one. With Whole Foods in the ring, the rest of the industry will soon be under competitive pressure to follow. Genetically modified crops have become so prevalent in the U.S. that chances are you've been buying and eating them for years. You just wouldn't know it from the label: the U.S. Department of Agriculture, unlike agencies in Europe and Japan, do not require GM foods to be labeled.