5. For the purpose of this Decision, 'dangerous substance' means any substance that has been or will be classified as dangerous in Directive 67/548/EEC and its subsequent amendments; 'heavy metal' means any compound of antimony, arsenic, cadmium, chromium(VI), copper, lead, mercury, nickel, selenium, tellurium, thallium and tin, as well as these materials in metallic form, as far as these are classified as dangerous substances.