Pharmaceutical Contaminants in Aquatic Environments: A Critical Synthesis of Sources, Ecological Risks and Bioremediation Strategies

Abstract

Pharmaceutical residues are now routinely detected in wastewater-impacted aquatic environments because medicinal compounds and their metabolites enter sewerage, industrial effluents, agricultural drainage and receiving waters through multiple, often continuous pathways. Their environmental significance cannot be inferred from occurrence alone: risk depends on potency, exposure duration, mixtures, transformation products, species sensitivity and the capacity of treatment systems to reduce biologically active mass. This critical narrative review integrates evidence on sources, ecological effects and bioremediation, with emphasis on wastewater-impacted freshwaters and on technologies that rely substantially on microbial, fungal, algal or plant-associated processes. Literature was selected through live searches of multidisciplinary and environmental or biomedical scholarly sources, supplemented by citation searching and DOI verification. The strongest causal ecological evidence comes from whole-ecosystem work with endocrine-active pharmaceuticals, while laboratory and field studies also support concern for behavioural disruption, chronic sublethal effects and antibiotic-driven selection for antimicrobial resistance. Nevertheless, extrapolation remains difficult because monitoring is dominated by parent compounds and targeted analytes, whereas mixtures and transformation products are incompletely characterised. Conventional activated sludge provides variable and compound-specific attenuation; apparent parent removal may reflect sorption or transformation rather than mineralisation. Membrane bioreactors, adapted bacterial consortia, white-rot fungi, microalgae and constructed wetlands can improve removal under favourable conditions, but evidence is uneven across scales and frequently relies on high test concentrations or parent disappearance. The synthesis indicates that no single biological technology provides universal control. Risk reduction is more defensibly pursued through source control, robust biological treatment and targeted polishing, supported by mass balances, transformation-product screening, effect-based endpoints and antimicrobial-resistance assessment. Future research should prioritise trace-level, full-scale comparisons and standardised demonstrations that connect chemical removal to reduced biological hazard.