Food coloring is the reason glace cherries are red rather than beige and that children's tongues sometimes appear freakishly blue. But man-made dyes may do more than make processed food look vibrant and whimsical. Some blame the additives for triggering behavioral problems in youngsters. Acting on research published in the Lancet, the European Parliament last year began requiring products containing synthetic food colors to carry warning labels saying that "consumption may have an adverse effect on activity and attention in children." Now, the U.S. Food and Drug Administration has scheduled a March hearing on whether food dyes adversely impact children's health. The Center for Science in the Public Interest, or CSPI, is asking the agency for a synthetic food-dye ban and to place warnings on products until the colors are removed.