The European Union decided to ban the use of two classes of flame retardants, in particular, PBDEs and polybrominated biphenyls (PBBs) in electric and electronic devices. This ban was formalised in the RoHS Directive, and an upper limit of 1 g/kg for the sum of PBBs and PBDEs was set. In February 2009, the Institute for Reference Materials and Measurements released two certified reference materials to help analytical laboratories better detect these two classes of flame retardants. The reference materials were custom-made to contain all relevant PBDEs and PBBs at levels close to the legal limit.