β-Blockers in the Environment: Challenges in Understanding Their Persistence and Ecological Impact

β-blockers are among the most highly consumed cardiovascular drugs worldwide, resulting in their classification as persistent and bioactive pharmaceutical pollutants. This review provides a mechanistically oriented synthesis of their environmental release, stereochemical and matrix-dependent transformation, biotic and abiotic degradation, and the ecotoxicological significance of their degradation products. Wastewater treatment plants are identified as the primary, yet variably efficient, emission sources to aquatic systems. Molecular structure, chirality, and interactions with environmental matrices are highlighted as key factors influencing transformation behaviour and residue persistence. Current evidence indicates that β-blockers and several transformation products retain pharmacological activity, driving organism- and community-level effects at environmentally relevant exposures. Major limitations in the field stem from methodological heterogeneity and uneven regional and temporal coverage, which continue to weaken long-term risk evaluation. By unifying analytical chemistry, pharmacological mechanistics, and environmental toxicology evidence, this review advances the narrative from descriptive occurrence reports toward systematic evaluation of transformation product persistence, mechanism-dependent residue stability, and their ecological implications.