Hospital wastewater as a reservoir of environmental hazards for humans: Implications for public and occupational safety and health in the era of One Health

Hospital wastewater (HWW) represents a complex and increasingly relevant source of environmental contamination. These effluents contain a wide range of pollutants, including pharmaceuticals, disinfectants, pathogenic microorganisms, antimicrobial resistance genes, heavy metals, radionuclides, and emerging contaminants such as micro- and nanoplastics (MNPs). Within the evolving European regulatory framework for urban wastewater treatment, HWW is now recognised as a critical matrix requiring targeted management strategies. This review critically examines current evidence on the composition of HWW, highlighting the role of MNPs as vectors for bioactive, toxic, and potentially genotoxic substances. Special attention is devoted to different processes that markedly influence the environmental fate, bioavailability, and toxicity of associated contaminants. Growing experimental evidence indicates that MNPs can enhance the persistence, mobility, and biological effects of hazardous compounds, amplifying potential risks to both environmental and human health, and focusing on the occupational risks associated with HWW for wastewater treatment plant operators and hospital maintenance workers. These workers may be exposed to complex mixtures of chemical and biological agents through aerosols, sludge, and direct contact, with possible oxidative, inflammatory, and genotoxic effects. The limitations of conventional wastewater treatment processes in removing emerging contaminants and MNPs are discussed, together with the potential of advanced technologies such as membrane bioreactors, advanced oxidation processes, and hybrid systems. In conclusion, the review highlights the urgent need for integrated monitoring strategies that combine chemical, biological, and toxicological assessments within a One Health framework to better protect environmental, public, and occupational health and to support future policy development and technological innovation.