RESUMEN
<p><b>OBJECTIVE</b>To study the correlation of toxicity with biodegradability (BODT) in order to promote QSBR development and understand the degradation mechanism.</p><p><b>METHODS</b>Toxicity of substituted phenols to river bacteria was determined by the turbidities that were measured using a spectrophotometer (UV-190) at 530 nm against a blank control. The biodegradability of substituted phenols was expressed as BODT and the DO concentrations were determined by the iodometric titration method.</p><p><b>RESULTS</b>The BODT and toxicity(log 1/IC50) of 12 substituted phenols to bacteria from the Songhua River were determined respectively. The correlation of biodegradability with toxicity was developed: BODT=8.21 (+/-2.22) pKa -32.44 (+/-8.28) log 1/IC50 +89.04 (+/-38.20), n=12, R2=0.791, R2(adj)=0.745, SE=9.134, F=17.066, P=0.001.</p><p><b>CONCLUSION</b>The BODT of substituted phenols was influenced by their toxicity and the ionization constant pKa. The stronger the toxicity, the less readily the compound was degraded by river bacteria.</p>