Studies on Acute Toxic Effects of Cd,Pb and As on Photobacterium Phosphoreum

The joint toxicity from equitoxic mixture and the toxicity of single material as cadmium and lead and that of arsenic were tested in lab with the germ Photobacterium Phosphoreum introduced as test samples.Comparing the expected and measured EC50 values,the toxicity enhancement index was used to evaluate the effect of joint toxicity.The single toxicity test results of cadmium,lead and arsenic showed that their EC50 values are 2.411,1.668 and 0.463 mg/L,respectively,i.e.,AsPbCd in toxic effect.For the Cd-Pb joint toxicity from equitoxic mixture,the EC50 value is 0.293 mg/L and the EC50 ratio of expected value to measured one is 6.7,i.e.,a synergistic toxic effect.However,for the Cd-Pb-As joint toxicity,the EC50 ratio is 1.3,i.e.,a superposed toxic effect.