Individual and combined toxicity of personal care products and pharmaceuticals at environmentally relevant concentrations due to chronic exposure of the freshwater microcrustacean Daphnia magna

Personal care products and pharmaceuticals, namely sodium diclofenac (DCF), octocrylene (OCT), and sodium dodecyl sulfate (SDS), are relevant chemical products classified as contaminants of emerging concern (CECs). They can enter aquatic ecosystems from various anthropogenic sources. This study examined the acute and chronic toxic effects of exposure to these substances, individually and in binary mixtures (OCT + SDS, SDS + DCF, DCF + SDS). Chronic effects were evaluated at environmentally relevant concentrations. To evaluate the mixtures, the Abbott method was used to predict acute toxicity using the inhibition ratio value, while for chronic effects, the concentration addition (CA) and independent action (IA) models were used for predictive assessment. According to EC50_48h values, the toxicity levels to D. magna were OCT > SDS > DCF. When exposed to binary mixtures, these compounds predominantly exhibited antagonistic interaction for acute effects. Regarding chronic effects, there were no observed effects at the environmentally relevant concentrations tested for individual and mixed exposure compared to the control. The locomotion parameter exhibited a difference in dispersion with increasing chemical concentration. These results can improve understanding of the damage produced by exposure to mixtures of different CECs.