Assessing mixture toxicity of disinfectants in zebrafish

• Autor(a) principal: Silva, Carla Ofélia Ferreira da
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/8056
• topic: Ecotoxicologia; Desinfectantes; Efluentes - Hospitais; Embriões; Peixes

Large quantities of chemicals (e.g. detergents and disinfectants) are used in hospitals for cleaning and disinfection. Their effluents consist of a mixture which can cause serious environmental problems. In this work, the effects of binary mixtures between three hospital disinfectants: glutaraldehyde (GA), formaldehyde (FA) or ortho-phthalaldehyde (OPA) and the surfactant benzalkonium chloride (BKC) on zebrafish early life-stages were studied. The assays were based on the OECD guideline on Fish Embryo Toxicity (FET) Test. Over 96 hours the organisms were daily inspected with stereomicroscopy, registering the mortality. The BKC, FA, GA and OPA showed high toxicity for zebrafish embryos presenting LC50 values at 96 h of 3.9 mg/l, 546.8 mg/l, 23.97 mg/l and 64.9 μg/l, respectively. Mixtures data was fitted to the independent action and concentration addiction models in order to verify which model best described the obtained results and to analyze possible interactive responses. At 96 hours, the results showed that the mixture toxicity of BKC and FA is best predictable by concentration addition with a dose level dependency deviation (antagonism at low dose and synergism at high dose), whereas concentration addition with an antagonist deviation function described the mixture of BKC and GA. For BKC and OPA, Independent action best described the mixture, with a synergism deviation function from the reference model. This study drives attention to the problem of the hospital effluents due the release of its complex mixtures and its toxicity that may represent a real environmental problem.