Abstract: The relative toxicity of a heterogeneous series of nitrogen-containing aromatics including substituted anilines, pyridines and nitrobenzenes was evaluated in the 48-h sublethal, static Tetrahymena pyriformis (ciliate protozoan) test system and compared with reported values for the 96-h lethal, flow-through Pimephales promelas (fathead minnow) test system. The ...