Toxicity of individual pharmaceuticals and their mixtures to Aliivibrio fischeri: experimental results for single compounds and considerations of their mechanisms of action and potential acute effects on aquatic organisms

In the first part of a broader study on the effects of individual and multicomponent mixtures of pharmaceutical active compounds, the authors used the Microtox® test system to analyze in detail the effects of 10 widely used human and veterinary pharmaceutical active compounds toward the bioluminescent bacterium Aliivibrio fischeri. The experimental results indicated moderate toxicity for the majority of the tested compounds. Comparison between experimental 50% inhibitory concentrations and those predicted from the quantitative structure–activity relationship models indicated that most of the tested pharmaceutical active compounds behave as polar narcotic compounds toward A. fischeri (only the antibiotic chlortetracycline seemed to have a specific mechanism of action). A comparison between the experimental results and a collection of acute toxicity data on other nontarget organisms indicated that in general A. fischeri has a comparable sensitivity to other aquatic species. However, according to the Globally Harmonized System of Classification and Labelling of Chemicals, the majority of the investigated chemicals can be classified as harmful or nontoxic for aquatic ecosystems. Finally, based on comparisons among the 95th percentile of measured environmental concentrations found in European Union water bodies and acute toxicity data on various aquatic organisms, no risk to aquatic life exists when the tested pharmaceutical active compounds are assessed as individual chemicals. Environ Toxicol Chem 2017;36:807–814. © 2016 SETAC