Transition metals and polycyclic aromatic hydrocarbons (PAHs) are co-contaminants at many sites. Contaminants in mixtures are known to interact with biological systems in ways that can greatly alter the toxicity of in...
详细信息
Transition metals and polycyclic aromatic hydrocarbons (PAHs) are co-contaminants at many sites. Contaminants in mixtures are known to interact with biological systems in ways that can greatly alter the toxicity of individual compounds. The toxicity (alone and in mixture) of Cu (a redox-active metal), Cd (a non-redox active metal) and phenanthrenequinone (PHQ) (a redox-active oxygenated PAH) were examined using the bioluminescent bacterium Vibrio fischeri. The co-toxicity of Cu/PHQ depend on their mixture ratio. Different interaction types (synergistism, antagonism, and additive) were observed in different combinations. The interaction types change from antagonism at a low Cu/PHQ ratio (1/4) to additive at intermediate Cu/PHQ ratio (2/3) to synergistic at higher Cu/PHQ ratios (3/2 and 4/1). In contrast to Cu/PHQ, the co-toxicity of Cd/PHQ did not change at different mixture ratios. The interaction types basically are additive. ROS-mediated toxic mechanisms of Cu, Cd and PHQ have been well established with several organisms using 2',7'-dichlorofluorescin diacetate (DCF ***) and Amplex Red fluorescence. Enhanced ROS production was observed in V. fischeri treated with the individual chemicals and their mixtures, suggesting alone and mixture toxicity of Cu, Cd and PHQ to V. fischeri involve ROS mechanisms. This study shows that not only the chemical mixtures, but also the mixture ratios can alter individual chemical toxicity and should be taken into account in risk assessment.
暂无评论