The European Chemicals Agency, ECHA, has published a list of over 21,000 REACH-registered substances mapped in its 'chemical universe'. The substances have been divided into five pools based on the regulatory actions in place, initiated or considered for them. It also highlights that there are still thousands of substances for which possible actions have not yet been determined. The chemical universe does not indicate whether a substance’s use is safe or not – it is mainly to help authorities focus their actions. The assignment to a pool is also not permanent – substances will move from one pool to another over time when new information becomes available or priorities change.