This Report provides some examples of substances and materials that may cause a sustained impediment in the recycling activities, and is intended to assist in the assessment requirements set out in the standard EN 13430. It describes substances or materials which cause problems or inhibit the recycling process, or which have a negative influence on the quality of recycled material, and for which it is considered that technological solutions will not be developed in the near future. These examples are however qualified by the fact that the recycling operations can vary from region to region and state to state, that technology is constantly changing, and that the use to which the recycled material is put will also determine whether such substances and materials are a problem.