Food labels will soon have to disclose in plain language whether the products contain peanuts, shellfish, eggs or other ingredients that could sicken people with food allergies.

A federal law that takes effect Jan. 1 requires food labels to list ingredients made from proteins derived from any of the eight major allergenic foods: milk, eggs, fish, crustaceans, wheat, tree nuts, soybeans and peanuts. The Food and Drug Administration says they account for 90 percent of all food allergies.

The 2004 Food Allergen Labeling and Consumer Protection Act was sparked by fears that many food labels either didn't include the allergens in their listed ingredients or listed them using names not easily recognizable by consumers.

A 1999 FDA study in Minnesota and Wisconsin found a quarter of the baked goods, ice cream and candy its scientists sampled failed to list peanuts or eggs as ingredients.

Food labels must now list the common name of the product as well as the name of the specific allergen it contains. A product containing a protein derived from milk called casein, for example, must list both "milk" and "casein" on its label. Labels also must specify the type of fish, crustacean or tree nut the product contains.

The FDA estimates 2 percent of adults and 5 percent of young children suffer from food allergies. Each year, about 30,000 people require emergency room treatment for food allergies and an estimated 150 die.