PHYSICOCHEMICAL PROPERTIES OF AROMATIC PHOSPHATE ESTERS AND THEIR PERSISTENCE AND LONG-RANGE TRANSPORTATION POTENTIAL

Introduction
 The RoHS Directive bans the use of polybromodiphenyl ethers (PBDEs). Recently, aromatic phosphate
esters such as triphenylphosphate and its dimeric phosphate ester have been used as a replacement for PBDEs. Especially the dimeric phosphates should be evaluated in terms of the environmental behavior and human exposure to them, because they are relatively new compounds. In the evaluation, 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 have measured the properties for PBDEs and some non-PBED flame retardants containing aromatic phosphate esters. Unfortunately, there is little experimental data on the physicochemical properties of liquid-type aromatic phosphate esters. In this study, therefore, we measured the physicochemical properties of two liquid aromatic phosphate esters. In addition, Henry's law constant of these compounds at 25 ºC was estimated from the measured property data. The measured properties were compared with those of PBDEs. Finally, using the OECD Pov & LRTP Screening Tool4, we briefly evaluated the Pov (overall persistence) and LRTP (long-range transport potential) of these chemicals.