For over 25 years, despite the general use of slag products in construction, there has been an ongoing argument about whether slag is a waste or a by-product. Still today, the situation concerning the classification of slag is not uniform within European member states. In various countries some of the slag types are considered as by-products, however in others they have a waste status.

Before the revision of the Waste Framework Directive – WFD - (Directive 2008/98/EC) in 2008, there was no definition of by-products in the European legislation. The WFD now allows for a clear definition of criteria characterising a by-product as well as a material which shall cease to be regarded as waste and finally becomes a useful product. 

Ferrous slag placed on the market meets the requirements of national as well as European harmonised standards and specifications related to both technical and environmental aspects with regard to the intended use. For this reason the European steel and slag industry considers slag to be a by-product. EUROSLAG is engaged in providing the necessary elements of proof to the EU Commission that slag is a by-product and not a waste.