ISO/TR 17098:2013 provides a non-exhaustive overview of substances and materials that can cause a sustained impediment to recycling activities and is intended to assist in the assessment requirements set out in ISO 18604.

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, where technical solutions are not expected to be developed in the near future.

These examples are, however, qualified by the fact that the recycling operations can vary regionally, that technology is constantly changing, and that the use to which the recycled material is put will also determine whether the presence of such substances and materials is a problem.