Food Addditives" means any substance , the intended use of which results or may reasonably be expected to result directly or indirectly , in its becoming a component or other wise affecting the charactertics of any food (including any substance intended for use in producing , manufacturing , packing, processing , preparing, treating , packaging , transporting or holding food ; and including any source of radiation intended for any such use) , if such substance is not generally recognized, among experts qualified as having been adequately shown through scientific procedures to be safe under the conditions of the intended use