Physical-Chemical Property Data for Dibenzo-p-dioxin (DD), Dibenzofuran (DF), and Chlorinated DD/Fs: A Critical Review and Recommended Values

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are of global concern due to their persistence, their tendency to bioaccumulate, and their extremely high toxicity. The fate of the PCDD/Fs in the environment is largely determined by their physical-chemical properties, such as solubility in water (S-W, mol m(-3)), solubility in octanol (S-O, mol m(-3)), and vapor pressure (P, Pa). It is not unusual that the range of reported values for a given property varies over several orders of magnitude, especially for the highly chlorinated congeners, and consequently, it is a challenge to select physical-chemical property data from the literature for use in chemical fate and risk assessments. In the current study, physical-chemical property data [P, S-W, S-O, Henry's law constant (H), partitioning coefficients between octanol-water (K-OW) and octanol-air (K-OA)] for 15 DDs and 17 DFs at 293-299 K are compiled from the literature and evaluated to select literature derived values that are then adjusted to conform to thermodynamic constraints using a least-squares adjustment procedure. We also present an analysis of available data on internal energies of phase change (Delta U-A, Delta U-W, Delta U-O, Delta U-OW, Delta U-AW, Delta U-OA) at 298 K, which describe the temperature dependence of the partitioning properties. The final adjusted values (FAVs) derived from this study are recommended as physical-chemical property data for PCDD/Fs for use in environmental fate modeling. The FAVs for internal energies of phase change can be used as a first approximation for estimating properties at temperatures other than 298 K.