Occurrence, Fate, and Ecotoxicological Effects of Steroid Hormones in Aquatic Environments

Steroid hormones constitute a group of emerging contaminants with high biological activity; their presence in aquatic systems is primarily linked to municipal wastewater, animal production, aquaculture, and pharmaceutical use. Their environmental significance lies in the fact that they can induce biological responses at very low concentrations, even within ranges considered environmentally low. This review synthesizes and analyzes the available evidence on the presence, environmental distribution, treatment, fate, and ecotoxicological effects of natural and synthetic steroid hormones in different aquatic matrices. The compiled results show wide variability in environmental concentrations, with estrone (E1) values of up to 3050 ng L−1 in effluents from wastewater treatment plants, 17α-ethinylestradiol (EE2) of 4608 ng L−1 in effluents, and progesterone of up to 16,687 ng L−1 in treated effluents. In surface waters, concentrations of up to 4152 ng L−1 for E1 and 1200 ng L−1 for EE2 were recorded. From an ecotoxicological perspective, reproductive, developmental, molecular, metabolic, and physiological alterations were documented at exposure concentrations as low as 0.4 ng L−1 for EE2 and 0.5 ng L−1 for levonorgestrel (LNG). However, the concentration associated with each response varied widely depending on the species, the compound, the developmental stage, the duration of exposure, and the experimental conditions. The available evidence indicates that conventional wastewater treatment may not completely remove these compounds, thereby facilitating their transfer to receiving ecosystems, while sediments may act as potential environmental reservoirs. Taken together, the findings highlight the need to assess steroid hormones using an integrated approach that simultaneously considers concentration, exposure, biological response, environmental persistence, and the specific characteristics of each compound, particularly in studies aimed at evaluating their ecological relevance.