Measurement of vapor pressures of some PBDES and Non-PBDE flame retardants and evaluation of their persistence and long-range transportation potential

Kuramochi, H.; Takigami, H.; Sakai, S. (2010) Organohalogen Compounds, 72: 1534


The RoHS Directive bans the use of polybromodiphenyl ethers (PBDEs). In addition, some PBDEs have been the newly listed as persistent organic pollutants (POPs) in the Stockholm Convention. Recently, research and development on non-PBDEs flame retardants used as alternatives to PBDEs receive increasing attention. Hexabromocyclodocecane (HBCD) and aromatic phosphate esters may be used as a replacement for PBDEs. However, HBCD is currently under review as the next POPs. In the research and development, to obtain a better understanding of the environmental fate and behavior of the alternatives as well as PBDEs and human exposure to them, the physicochemical properties of those compounds such as vapor pressure (pi), water solubility (Sw),and 1-octanol/water partition coefficient (Kow) are of fundamental importance. In our previous works1-3, we measured the properties except for pi. Unfortunately, there is little experimental data on pi. Even if pi values are available, the values vary among the literature, and also differ significantly from the values predicted by some methods. In this study, therefore, pi of three PBDEs, HBCD isomers, and two aromatic phosphate esters was measured using the gas saturation method, and then the temperature dependence of pi, namely enthalpy of sublimation or evaporation, was determined. Furthermore, Henry's law constant of these compounds at 25 ºC was estimated from our previous Sw data of them. Finally, using the OECD Pov & LRTP Screening Tool4, we briefly evaluated the Pov (overall persistence) and LRTP (long-range transport potential) of these chemicals.