More companies are lining up behind environmental groups by promising to stop using a chemical compound that threatens the Earth's ozone layer.

The latest move away from chlorofluorocarbon, or CFC, compounds comes from the 15 or so companies who use them to make plastic foam food packages such as egg cartons.They'll be using substitute compounds by the end of the year, their trade association, the Foodservice & Packaging Institute, announced Tuesday. That will make it the first industry to give up CFCs completely.

Consumers should notice little change since foam packages will still be on the shelves.

The announcement came after consultations with three major environmental groups, the Natural Resources Defense Council, the Environmental Defense Fund and Friends of the Earth. Friends of the Earth already had persuaded some fast-food chains to stop using CFC-made foam clamshell hamburger warmers, and some cities have banned these products.