Manufacturers, importers and downstream users of substances are obliged to perform a self-classification under the CLP Regulation (as required by CLP and also in the framework of registration of substances under REACH), determined through the application of the CLP classification criteria. 

There can be multiple classifications for the same substance due to: 

— the different composition, form or physical state of the substance placed on the market; 

— a manufacturer or producer identifying insufficient information to assess that hazard class or category (which they will report as ‘data lacking’, ‘inconclusive’, or ‘conclusive but not sufficient for classification’); 

— the manufacturer, importer or downstream user has access to, or has generated, different or additional data. 

Self-classifications may be used to identify which hazard classes and categories have already been identified by other notifiers going beyond the harmonised classification and should serve as general information. It is recommended to check in particular those self-classifications showing the highest number of notifiers. There are ongoing efforts to get notifiers to agree on self-classifications. However, if no harmonised classification is available and only self-classifications for the substances in question are available, the waste holder should employ its best efforts to assign a classification, based on the published self-classifications in the C&L inventory and taking particular notice of the classification transmitted via the SDS of the relevant substance or mixture to the operator generating the waste.