Toxicity Study for Halogenated Aromatics to Mixed Bacteria in River Water

The bacterial growth inhibition test was used to determine toxicity of the halogenated aromatics on the mixed bacteria from the Yangtze River. The concentration values causing 50% reduction of bacteria growth for 24 hr (IC50) and the maximum tolerance concentration for 7 d (MATC) were gained according to the concentration-response curves. An obvious linear relationship was found between the two toxicity descriptors. The following quantitative structure- activity relationships were developed by using the valence molecular connectivity index method: -lgIC50 = 0.8266Xpcv- 0.2363Xpv + 3.811 (R2 = 0.833) and -lgMATC = 1.2016Xpcv-0.3783Xpv + 4.614 (R2 = 0.900). The two equations were found to fit well. It suggested that the models derived from the molecular connectivity index could be used successfully to predict the toxicity of halogenated aromatic compounds.