Uptake Through Feeding and/or Culture Medium of 0.5% Dimethyl Sulfoxide (DMSO): Biological Response of Daphnia magna and Ceriodaphnia dubia in Ecotoxicity Tests

Dimethyl sulfoxide (DMSO) is an aprotic solvent widely used in ecotoxicological assays, suitable for solubilizing a wide range of polar and non-polar substances. The aim of this study was to analyze the species-specific biological response of the model organisms Daphnia magna and Ceriodaphnia dubia to 0.5% DMSO, under feeding conditions. Both species were exposed in culture medium, with or without 0.5% DMSO, to the unicellular algae (Raphidocelis subcapitata, Tetradesmus obliquus), either individually or in combination; the algae were pretreated or not pretreated with 0.5% DMSO. The exposure was carried out in acute (24 h and 48 h) and chronic (72 h and 168 h) ecotoxicity tests. The experimental results suggest that a lower DMSO concentration limit (<0.5%) would be appropriate for C. dubia due to its greater sensitivity to the solvent. Finally, considering the ingestion of DMSO-contaminated algae, it can be concluded that, under certain experimental conditions, the solvent ingested through the diet may significantly affect the mortality of both D. magna and C. dubia.