Estimating bioconcentration factors, lethal concentrations and critical body residues of metals in the mollusks Perna viridis and Mytilus edulis using ion characteristics

Quantitative structure-activity relationships (QSARs) for metal bioconcent ration factors (BCF) and median acute lethal water concentrations (LC50) were developed for two species of mollusks, Perna viridis and Mytilus edulis. These endpoints were related to four metal ion characteristics, the covalent index (X(m)(2)r) (r represents the ion radius in angstrom), the softness index (sigma(p)), the hydrolysis constant (K-OH) and the ionic index (Z(2)/r). The BCF and LC50 were significantly correlated to X(m)(2)r. The coefficients of determination r(2) for the relationships with other metal descriptors were much lower. Critical body residue (CBR) QSARs were derived by multiplying the X(m)(2)r-based BCF and LC50 regressions. The CBRs were independent of the covalent index X(m)(2)r, as BCF and LC50 scaled to X(m)(2)r with slope that had opposite signs. Comparison of the estimated CBRs with independent empirical values confirmed the predicted trends, but substantial deviations were noted too.