in may 2007, the legislature of the state of maine passed a bill phasing out the use of decapbde. 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. at an international level, in may 2009 the parties of the stockholm convention on persistent organic pollutants (pops) decided to list commercial pentabde and commercial octabde as pop substances. this listing is due to the properties of hexabde and heptabde, which are components of commercial octabde, and to the properties of tetrabde and pentabde, which are the main components of commercial pentabde. in 2017, it was decided to also list decabde.