As many as 6,000 food manufacturers can expect inspectors from the Food and Drug Administration, as the agency gears up to make sure ingredients that cause common allergic reactions aren't getting into food accidentally.

The FDA decided on the inspections, which would focus on candy makers, bakeries and other processors, after recently testing several plants in Minnesota and Wisconsin. One-fourth of the cookie, ice cream and candy makers tested had ingredients such as peanuts that weren't disclosed on product labels.

"We'd like to go out and see if that is true in the rest of the nation," said Kenneth Falci, an FDA official who briefed industry officials on the agency's plans at the Institute of Food Technologists annual conference over the weekend.

Training for the 2,500 inspectors will take up to a year and the inspections are expected to take two years to complete.

Food makers are supposed to disclose all ingredients except for flavorings, colorings and spices, but allergenic ingredients sometimes slip into foods undetected because machinery hasn't been cleaned properly between different products, industry officials say.

The FDA also has asked food makers and their ingredient suppliers to study all of the thousands of flavorings, colorings and spices that are in use to identify those that are made from common allergens, Falci said.

Under federal law, companies are not required to disclose the composition of flavorings, colorings and spices on food labels.

Eight food groups are responsible for most allergic reactions: Crustaceans such as crab and lobster; peanuts, eggs, fish, milk, soy, tree nuts such as almonds and walnuts; and wheat.

In Minnesota and Wisconsin, the FDA asked state inspectors to look just at peanut and egg allergies.

The inspectors found that allergens usually got into foods undetected because bakers used the same utensils to stir separate mixes or reused baking sheets between batches. At one candy company, certain machinery was washed only once a year, even though both peanut-containing and peanut-free chocolates were run through the equipment.

The food industry recently released voluntary labeling standards that call for disclosure of the sources of flavorings that could cause allergic reactions. Labels also are supposed to use more easily understood terms for ingredients like casein, a milk product.

Falci suggested that the FDA may restrict the use of some precautionary statements that some manufacturers are putting on all their products to protect themselves against lawsuits. One common statement reads, "May contain peanuts." Such a label could be considered "false and misleading" if there is little chance the food could contain an allergen, Falci said.

The food industry, meanwhile, is wrestling with whether to start testing foods for allergens. Tests have been developed that can detect minute amounts of allergenic proteins for peanuts, milk and eggs.

Some companies won't do the testing on advice of their attorneys, industry officials say. The fear is that the results could be used against them in lawsuits.

"Before you actually do the testing you have to sit back and say, what are you going to do with the results," said Martin Hahn, an attorney who specializes in food law. But, he said, the tests could help companies discover problems in their plants.

Some 7 million Americans who suffer from food allergies rely on ingredient labels to tell which processed foods are safe for them to consume. Some food allergies, particularly peanut allergies, can be fatal, claiming an estimated 150 lives a year. Allergy-related food recalls jumped 20 percent last year to more than 120, according to the FDA.

The Associated Press contributed to this report.