Environmentally Relevant Properties of All 209 Polychlorinated Biphenyl Congeners for Modeling Their Fate in Different Natural and Climatic Conditions

The temperature dependence of physical properties and degradation lifetimes in the environment of all polychlorinated biphenyl (PCB) congeners (N = 209) were determined. For physical properties, the coefficients A and B in equations log(property) = A(property) - B(property)/T(K) were determined by thermodynamic and QSPR methods and compared with the results of independent methods in the literature. The coefficients ApI and BpI for liquid state vapor pressure P-L, As and Bs for solubility in water S-w, Ah and Bh for volatility k(H) (or k(H) = P-L/S-W), and Aow and Bow for lipophilicity (K-ow), stored in the database of the fate model program, allowed automatic temperature corrections for realistic fate and exposure modeling at variable environmental conditions. Half-lives HL(i) for degradation in compartments air (i = 1), water (2), soil/plants (3), and sediment (4) were determined by combination of the photolysis and biodegradation rates (from the literature) at one reference temperature (mostly 25 degrees C). Examples of validation procedures for both physical properties and degradation rates were given. Temperature dependences were possible to compare with sufficient independent PCB sets only for vapor pressure. Other property sets could be compared statistically at 25 degrees C only. Field observations gave opportunities to validate estimated properties indirectly, e.g., with fate modeling and kinetics. Such a case was presented about the role of mono-ortho hexa-CB congeners 156, 157, and 167 as precursors in the formation of toxic CB126, the most potent observed factor to yolk sac mortality (YSM) from 1988 to 1992 of the fry of Simojoki River salmon (N = 40).