Drugs in the environment, viruses in the balance: a review of the untold nexus of pharmaceuticals and virology.

OBJECTIVES: The pervasive contamination of aquatic and terrestrial ecosystems by active pharmaceutical ingredients (APIs) is a well-documented environmental challenge. However, the impact of this pollution on the most abundant biological entities on Earth viruses has remained a critical blind spot. This review provides the first integrated synthesis of the bidirectional nexus between pharmaceutical pollution and environmental virology. METHODS: A comprehensive literature search was conducted in PubMed, Web of Science, and Scopus using search terms related to pharmaceuticals, viruses, and the environment. Additional targeted searches were performed for specific drug classes and viral systems. Articles were selected based on their relevance to pharmaceutical-viral ecology interactions. RESULTS: We introduce a novel dual-pathway framework positing that APIs influence viral ecology through: (i) direct "drug-to-virus" interactions, where non-antibiotic compounds can physiochemically enhance viral stability and infectivity, and (ii) indirect "drug-to-host-to-virus" pathways, where antibiotics stress bacterial hosts, triggering prophage induction and fundamentally altering viral community dynamics. These mechanisms have profound implications, including the phage-mediated dissemination of antibiotic resistance genes, the selection for antiviral resistance in environmental reservoirs, and the potential for immunosuppression in aquatic fauna. Extending this framework to emerging biopharmaceuticals, we examine the environmental fate of vaccine nanoparticles and the ecological risks posed by gene therapy viral vectors. CONCLUSION: We propose a next-generation environmental risk assessment paradigm that integrates viral ecological outcomes, moving beyond traditional chemical-focused models. This review advances the field from fragmented evidence to a unified framework for environmental public health policy and practice.