QSAR MODEL FOR THE PREDICTION OF THE HALF LIFE OF POLYCHLORINATED BIPHENYLS IN HUMANS

Abstract

The elimination rate of the polychlorinated biphenyls (PCBs) in humans is of great environmental importance, as represented by their half-lives (t1/2). Based on the literature, a database of this toxickinetic variable for PCBs in humans is elaborated. 14 PCB structures with known half-lives are optimized, making a previous scan of the dihedral angle between the two phenyl rings, using AM1 to find the most stable conformation. Substituted mono-orto PCBs present an approximate dihedral angle of 120°, and the substituted poly-orto of 90°. Several descriptors are calculated from optimized structures using B3LYP/6-31G**. The molecular descriptors are associated with the t1/2 values by multiple lineal regression analysis. This reveals that the t1/2 of PCBs is a function of the sum of atomic charges on the chlorine atoms (åQCl) and the sum of atomic charges for the carbon atoms in metaposition (ΣQC-meta). The regression coefficient value of the prediction model is 0.84, and the Pvalue is

Keywords

• PCBs
• half life
• atomic charge
• congener
• QSAR
• molecular descriptor.