Qualitative and Quantitative Analysis of Certain Aspects of the Cytotoxic and Genotoxic Hazard of Hospital Wastewaters by Using a Range of In Vitro Assays

Health care facilities and hospitals generate significant amounts of wastewater which are released into the sewage system, either after a preliminary treatment or without any further treatment. Hospital wastewater may contain large amounts of hazardous chemicals and pharmaceuticals, some of which cannot be eliminated entirely by wastewater treatment plants. Moreover, hospital effluents may be loaded with a plethora of pathogenic microorganisms or other microbiota and microbiome residues. The need to monitor hospital effluents for their genotoxic hazard is of high importance, as detailed information is scarce. DNA-based information can be acquired directly from samples through the application of various molecular methods, while cell-based biomonitoring assays can provide important information about impaired cellular pathways or mechanisms of toxicity without prior knowledge of the identity of each toxicant. In our study, we evaluated samples of chlorinated hospital wastewater discharged into the sewage system after this disinfection process. The assessment of cytotoxicity, genotoxicity and mutagenicity of the hospital effluents was performed in vitro by using a broad battery of biomonitoring assays that are relevant for human health effects. All the tested hospital wastewater samples could be classified as potentially genotoxic, and it is concluded that the microbiota present in hospital wastewater might contribute to this genotoxic potential.

Bioindicators of wastewater ecotoxicity

Wastewater, especially containing hospital effluents, exhibits high chemical complexity and specificity since it includes various chemicals, biocides, pharmaceuticals, surfactants, radionuclides, disinfectants and pathogens. Biological tests provide true evidence of the wastewater quality and unlike chemical analytical tests show comprehensive pollution effects on the environment and human health. Normalized conventional bioassays are not sensitive enough for ecotoxicological evaluation of wastewater and there is a great need for the development of suitable sensitive bioassays in order to characterize properly the residual toxicity of treated effluents. Provisions of binding EU legislation regarding protection of animals used for scientific purposes and legislation dealing with test methods for identification and classification of health hazard of chemicals, pharmaceuticals, biocides, medical devices and consumer products such as cosmetics for environmental ecosystems and for man require to employ alternative toxicological methods respecting the 3Rs concept with priority given to methods in vitro. The Fish Embryo Test (FET) is identified as a relevant, reliable and efficient alternative test method in vitro for determination of acute toxicity for fish. Using the FET, additional toxicological endpoints may be investigated to assess organ specific bioaccumulation, genotoxicity and mutagenicity, developmental toxicity, teratogenicity, various forms of neurotoxicity or endocrine disruptivity. The addition of multiparametric sensitive endpoints makes the FET a true alternative in vitro assay and a powerful tool in toxicology.