On September 14, 2021, the United Nations (UN) published an electronic version of the ninth revised edition (Rev 9) of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) available for free for consultation purposes. The amendments to the eighth revision of the GHS (Rev 8) include extensive revision of Chapter 2.1 (explosives) to address explosion hazard determination better when explosives are not in transit; the revision of decision logic; the revision of the classification and labeling summary tables in Annex 1; the revision and further rationalization of precautionary statements; and the updating of references to Organization for Economic Cooperation and Development (OECD) test guidelines for the testing of chemicals in Annexes 9 and 10. In addition, several format changes to decision logic are noted throughout. The decision logic provides clarification on the process for how to arrive at the appropriate classification. For more information, please read the full memorandum.