ミジンコヘのクロロフェノール類の毒性と構造活性相関

抄録

Toxicity of phenol and 7 chlorophenols from mono-Cl to penta-Cl on 3 species of daphnia, Daphnia magna, Daphnia carinata and Daphnia pulex has been determined according to OECD guideline for testing of chemicals. The responses of each daphnia to chemicals were measured by acute immobilization of young daphnia less than 24 h old (24 h-EC₅₀) and reproduction inhibition during 14 d (14 d-Maximum Acceptable Toxicity Concentration, MATC). The 24 h-EC₅₀ values were correlated with 6 physico-chemical parameters of chlorophenols. The parameters employed in this quantitative structure-activity relationship (QSAR) analyses were : n-octanol/water partition coefficient, log P_OW ; dissociation constant, pK_a ; Hammett Σσ constant ; index of valence molecular connectivity, ¹χ^V ; perimeter of the efficient cross section of molecule, ΣD ; melting point, mp. In immobilization studies, 24 h-EC₅₀ values of each daphnia decreases as substituted chlorine atom increases and QSAR study shows that log P_OW, a parameter of hydrophobicity, gives the best correlation. Toxic responses of 3 kinds of daphnia are almost the same each other and 24 h-EC₅₀ value of each chlorophenol is almost the same as 96 h-LC₅₀ in fish, P. reticulata. On the other hand, in the reproduction inhibition study using Daphnia magna, MATC values of mono-, di-, tri-, tetra- and pentachlorophenol are almost the same each other and no relationship was found between MATC values and substituted chlorine numbers.