Evaluation on the Binary Joint Toxicity of Phenol with Substituted Phenols to photobacterium phosphoreum Using Four Evaluating Methods

Binary joint toxicities of phenol with 14 substituted phenols to photo bacterium phosphoreum were determined with the concentration ratio of equal toxic unit (1:1), based on the single toxicity tests of above compounds. Four common-used evaluating methods, toxic unit (TU), additive index (AI), mixture toxicity index (MTI) and similarity parameter (λ), were used to evaluate the types of the binary joint toxicities. And the mechanism of joint toxicity was discussed preliminarily on the basis of the observed data. The results showed that the toxicities of substituted phenols to photobacterium phosphoreum were influenced by the variety, quantity and position of the substituents. Most of the binary mixtures of phenol with substituted phenols presented synergistic effect and others presented addition or antagonistic effect. For the same binary mixture of phenol with substituted phenols, the results of joint action types were incompletely identical using different evaluating methods. TU and MTI were recommended in this work because of their more sensitivity than AI and λ.