Aquatic toxicity evaluation of copper-complexed direct dyes to the Daphnia magna

Abstract The aquatic toxicity of a series of copper-complexed direct dyes based on benzidine congeners, 2,2′-dimethyl-5,5′-dipropoxybenzidine and 5,5′-dipropoxybenzidine, were evaluated in acute toxicity studies using Daphnia magna. The purpose of the research described in this paper was to use bioassays with daphnids to determine the aquatic toxicity of metallized direct dyes synthesized. The results clearly show that all of the copper-complexed dyes examined were highly toxic to daphnids and more toxic than unmetallized new direct dyes as expected. The study also suggested that the assay with D. magna was an excellent method for evaluation of dyes for aquatic toxicity.