Worldwide, 395 million acres of farmland were planted in 2011 in biotech crops, 30 million more than 2010, say the figures in this year's International Service for the Acquisition of Agri-biotech Applications report, out Tuesday. The amount of land devoted to genetically engineered crops grew 8% last year, down from 10% growth in 2010. The first biotech crop was approved for use in 1996.

The United States still leads the world in GM plantings, with 170 million acres in 2012, which produce 95% of the nation's sugar beets, 94% of the soybeans, 90% of the cotton and 88% of the feed corn.

Genetic engineering seeks to boost crop production or lower costs. The plants are often genetically modified to resist weed killers or to generate their own insect repellant.

Only two biotech crops are grown in the European Union, a tiny amount of its feed corn and just 245 acres of potatoes. Fears over these crops have included possible health concerns, worries about damaging traditional agricultural practices and a strong feeling on the part of some that they are "unnatural."

Now two other controversial issues loom, including the possibility that a farmed salmon species genetically engineered to grow faster might be approved by the Food and Drug Administration in the coming year, and the re-introduction of genetically engineered alfalfa.

The imminent possibility of the genetically engineered salmon "is a major watershed: Animals are different from plants. A genetically engineered animal is a whole different thing, and to not have them labeled is disturbing," says Jean Halloran, director of food policy initiatives for Consumers Union in Yonkers, N.Y.

Genetically modified alfalfa had been banned after a lawsuit in 2007, but the U.S. Supreme Court reversed the ban in 2010. Opposition came in part from organic farmers, fearing that genetically modified alfalfa pollen could contaminate organic alfalfa fields, making it impossible for that alfalfa to be sold as organic and marketed as organic cow feed. "That will really threaten one of the core organic products, which is organic milk," Halloran says.

Last year also marked the first time that 50% of biotech crops were grown in the developing world, rather than the industrialized world. The U.S. grew 45% of the biotech crops in 2011, followed by Brazil with 17%, Argentina with 16% and India and Canada each with 6%.

Brazil and Argentina mostly grow biotech soybeans, feed corn and cotton. India only grows biotech cotton. Canada grows biotech canola, feed corn, soybean and sugar beets.

The most common genetic modification is herbicide tolerance, where plants are given a gene that allows farmers to spray them with the weed killer glyphosate, known to most home gardeners as Roundup, without harming them. The other commonly used trait is the addition of a gene from a soil bacteria called Bacillus thuringiensis that allows plants to produce their own insecticide.

Critics note that genetically engineered seed can cost more than conventional seed, but for many farmers, especially larger and more technologically savvy ones, the savings they represent in time and diminished insecticide and pesticide use makes them economical.

Critics have long said that some insects that biotech crops are supposed to keep at bay are becoming resistant to the insecticide the crops carry. Recent research has shown that some western corn rootworms in Iowa had become resistant to corn meant to ward them off. And there have been at least 10 confirmed weeds resistant to glyphosate that are estimated to affect more than 7 million acres of farmland, says Greg Jaffee, director of biotechnology project at the Center for Science in the Public Interest in Washington, D.C.