QSARs in phytotoxicity

Abstract

The effect of 64 priority pollutants on the growth of Lactuca sativa in nutrient solution was determined, and quantitative structure-activity relationships (QSARs) were established relating EC 50 values with octanol/water partition coefficients (log K ow) of the test chemicals. Test periods were 2–3 weeks and EC 50 was based on fresh weight of shoots. Phytotoxicity of the (chloro)(methyl)phenols and (chloro)anilines was correlated with lipophilicity ( r = −0.88 and −0.84 respectively), while the correlation for chlorobenzenes was much weaker ( r = −0.60). The toxicity of the other compounds tested [alcohols, amines, (chlorinated) alka(e)nes and others] showed a poor correlation with lipophilicity ( r = −0.61), but the correlation was significantly improved when compounds with log K ow < 1 were left out ( r = −0.71). Most of the latter compounds are nitrogen-containing compounds. The relation between phytotoxicity of all tested compounds and lipophilicity was: log EC 50 ( μmol/l) = −0.71 log K ow + 3.64 ( r = −0.76) if compounds with log K ow < 1 are left out.