Oxidative stress induced by water from a hospital effluent of the city of toluca, mexico, on hyalella azteca

The wide range of activities performed in hospitals (care, diagnosis, hygiene, maintenance, research) require the use of a large variety of potentially ecotoxic substances such as surfactants, disinfectants, and pharmaceuticals. Once used or excreted by a patient, these compounds combine with hospital wastewater (HWW) in stable or unstable, metabolized or non-metabolized forms and then flow directly into the municipal wastewater network, generally without any prior treatment. Also, wastewater treatment plants (WWTPs) are usually not equipped to eliminate the pollutants present in these effluents. In Mexico there is no legislation regarding the entry of emerging contaminants into water bodies, and WWTPs do not use effective methods to remove pharmaceutical products. According to the National Water, primary treatment consists in adding chemicals in order to increase the coagulation, flocculation, and sedimentation of wastewater, followed by filtration. Hospitals in Mexico do not have wastewater treatment systems, and any pharmaceutical residues are typically released directly into the environment. Therefore, pharmaceutical concentrations are higher in water bodies located downstream from hospitals, reaching levels in the mg/L range. Micropollutant concentrations in HWW can be more than 150-fold higher than in municipal effluent. This may help explain the presence of hospital-generated pollutants in WWTPs and their effluents as well as in various components of the environment such as surface and groundwater and soil. Diverse studies have shown that pollutants present in HWW that can induce different responses in the aquatic organisms show adaptive response in contaminated aquatic environments and have been suggested for use as a bioindicators in toxicity assays. In this chapter, the toxicity of a hospital effluent from Mexico was evaluated through oxidative stress biomarkers using Cyprinus carpio as a bioindicator species. The results showed that the main contaminants found were metals and some drugs from different therapeutic groups. The biomarkers of oxidative stress increased statistically significantly with respect to the control organisms. The results allow us to conclude that the effluents of the hospital studied are capable of generating oxidative stress, putting at risk the integrity of the organisms evaluated.