The dangerous substances

Les substances dangereuses

The effects of a Seveso industrial accident depend on the release of a dangerous substance, its properties, but also its state (gaseous-liquid-solid) and the environment into which this substance is released.


The dangerous substances are various. They have been classified, in the European legislation, either according to their name (Annex 1, Part 2), or according to their properties (Annex 1, Part 1 : toxic, explosive, oxidizer, etc.).

In the new Seveso III directive, the classification is based on the global GHS system.

Globally Harmonised System of Classification and Labelling of Chemicals (GHS) is a worldwide harmonised standard for classifying and labelling chemical substances and mixtures.

The system was developed by the United Nations and is based upon various existing systems in the world.

The labelling is based upon the following elements :

  • One or more hazard pictograms or danger symbols, according to the hazard class;
  • A signal word (“danger” or “warning”) according to the products’ danger category ;
  • One or more hazard statements describing the risk in relation with the hazard class and category ;
  • One or more precautionary statements giving indications as to how to handle the product so as to minimize the risks to the user and to other people or the environment.