R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous substances and preparations. The list was consolidated and republished in Directive 2001/59/EC, where translations into other EU languages may be found.
These risk phrases are used internationally, not just in Europe, and there is an ongoing effort towards complete international harmonization.
Note: Missing R-numbers indicate phrases that have been deleted or replaced by other phrases.