European hazard symbols for chemicals are pictograms defined by the European Union for labeling chemical packaging (for storage and workplace) and containers (for transportation). They are standardized currently by the CLP/GHS classification.
The hazard symbols for chemicals were defined in Annex II of Directive 67/548/EEC. A consolidated list with translations into other EU languages was found in Directive 2001/59/EC (See the links section).
The 'n' in Harmful (Xn) stands for the French word nocif (harmful) and the Italian word nocivo (noxious).