Toxicity of wastewater from health care facilities assessed by different bioassays.

OBJECTIVES: The purpose of this study was to determine toxicity of wastewater from hospitals in the Czech Republic using traditional and alternative toxicological methods. The pilot study comprised weekly dynamics of sewage ecotoxicity of treated wastewater from one hospital in two different seasons. A detailed investigation of wastewater ecotoxicity, genotoxicity and reprotoxicity followed in five different hospitals. METHODS: The seven following bioassays were used in this study: algal growth inhibition test (ISO 8692), Vibrio fischeri test (ISO 11348-2), Daphnia magna acute toxicity test (ISO 6341), Allium cepa assay, Ames test (OECD TG 471), Comet assay and YES/YAS assay. RESULTS: The wastewater ecotoxicity during one week showed no differences in separate working days, however, higher toxicity values were recorded in May compared to November. In the following study, samples from two of the five hospitals were classified as toxic, the others as non toxic. Genotoxicity has not been confirmed in any sample. In several cases, wastewater samples exhibited agonist activity to the estrogen and androgen receptors. CONCLUSION: The study demonstrated different levels of toxicity of treated hospital wastewater. Variable sensitivity of individual bioassays for tested wastewater samples was recognized. A more extensive study including proposal for improvement of hospital wastewater treatment within the Czech Republic can be recommended with the aim to decrease the discharge of toxic chemicals into the local sewage system and the environment.

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.