Consumer advocates, environmental groups, fishermen and retailers reacted strongly to the federal government's announcement Thursday approving genetically modified salmon for consumer use. The landmark approval - the first genetically engineered food animal endorsed for sale in the United States - has sparked a passionate response ... especially because it will not require special labelling. Around 2 million people previously filed public comments against the FDA's approval of what opponents call Frankenfish," and the Center for Food Safety announced Thursday that it would sue the FDA in response. "This sets the bar incredibly low for engineered animals," said Michael Hansen, senior scientist at Consumers Union. "There were serious problems with the safety assessment." At least 60 retailers - including chains like Safeway, Target, Whole Foods and Trader Joe's, as well as local independent grocers like Bi-Rite and Rainbow Community Market - have made a pledge with Friends of the Earth not to sell the salmon when it goes to market. Chief among concerns about the GMO salmon is its potential for causing allergies and its ability to contaminate wild populations. Testing for potential allergens was only done on a very small sample size. The tested fish actually did show a higher allergenicity. Critics are also concerned about the fish's ability to escape and cause environmental harm.