As new research becomes available, an ingredient that might not have been considered problematic may now be an ingredient of concern or unacceptable. Depending on the degree of concern, we will either immediately remove it from sale, or we will 'grandmother in' the ingredient and allow products containing it to remain on the shelf while we encourage vendors to reformulate. In some instances, we allow an ingredient in a very limited set of specific products, because it serves a very specific purpose and there are no alternative options available.