Some excipients, binders, or fillers are "bad" because they can contribute to unwanted reactions in some people with heightened sensitivities. Artificial colors, dyes, preservatives, or coating agents have been implicated for years as possible concerns, though not all artificial ingredients carry the same potential for harm. Some inactive ingredients (like some vitamins) may be derived from either a natural source (plant, mineral) or an artificial source (chemical). Although labels are not required to state the source of inactive ingredients, quality manufacturers often opt for the natural source whenever possible for a final product that may offer less potential for adverse reactions in those who may be sensitive.