The impacts of antihistamines drugs in the mussel species Mytillus edulis: biochemical alterations induced after chronic exposure to cetirizine Miguel Teixeira*, Etelvina Figueira, Amadeu M.V.M. Soares, Rosa Freitas 1Departamento de Biologia & CESAM, Universidade de Aveiro, Portugal *mail to: miguel.monteiro@ua.pt Introduction Material and Methods Duration: 28 days 5 CTZ concentrations Salinity: 25g/L Volume: 3L per container Continuous aeration Temperature 18 ± 1ºC Photoperiod 12:12h (light/dark) Feed 3 times per week Biochemical analysis 5 individuals/aquarium Cetirizine concentration levels quantified by ELISA [2] Antihistamines are among the most commonly used pharmaceuticals worldwide. One of these drugs is cetirizine (used in Zyrtec®). During sewage treatment, the concentration of antihistamines, in a general, may drop up to an average of 16-36% [1] reaching the environment in relatively relevant concentrations. The effects of cetirizine in aquatic organisms, has not been studied despite the presence of this drug in different aquatic systems. Thus, this study undertook a biochemical approach, including different oxidative stress markers, TO ASSESS THE POSSIBLE ALTERATIONS INDUCED IN THE MUSSEL MYTILLUS EDULIS AFTER A LONG-TERM EXPOSURE TO ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF CETIRIZINE.   Results The biochemical parameters in yellow and protein content were determined as decribed by Carregosa et al. (2014). SOD activity increased along the increasing cetirizine concentrations, but no significant differences were noticed among conditions. The total glutathione increased along the increasing cetirizine concentrations, but no significant differences were noticed among conditions. Biomarkers involved in oxidative stress response. 0.0 mg/L   Results are expressed as a mean ± standard deviation. Significant differences (p ≤ 0.05) among cetirizine concentrations are represented with letters. Protein content significantly increased at the two higher exposure concentrations, probably reflecting the increase on enzymes production LPO levels increased with the increase of exposure concentrations, with no significant differences to control only at the lowest concentration. CAT activity increased with the increase of exposure concentrations, with significant differences between the highest and the two lower (CTL and 0.3 µg/L) concentrations. GSTs activity decreased along the increasing exposure gradient, with significant differences between the highest concentration and the control. Conclusions CETIRIZINE WAS CONSIDERED HARMFUL TO THE M. EDULIS HEALTH STATUS, AFTER CHRONIC EXPOSURE TO ENVIRONMENTAL RELEVANT CONCENTRATIONS SINCE, ALTHOUGH THE ANTIOXIDANT DEFENSE SYSTEM WAS TRIGGERED, IT WAS NOT CAPABLE OF PREVENTING THE OXIDATIVE STRESS THAT WAS HIGHER IN THE PRESENCE OF THIS CONTAMINANT THAN UNDER CONTROL CONDITIONS References Acknowledgments This work was supported by CESAM (UID/AMB/50017), to FCT/MEC through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. [1] Kosonen, J., & Kronberg, L. (2009). The occurrence of antihistamines in sewage waters and in recipient rivers. Environmental Science and Pollution Research, 16(5), 555–564. http://doi.org/10.1007/s11356-009-0144-2 [2] Calisto, V., Bahlmann, A., Schneider, R. J., & Esteves, V. I. (2011). Application of an ELISA to the quantification of carbamazepine in ground, surface and wastewaters and validation with LC-MS/MS. Chemosphere, 84(11), 1708–15. http://doi.org/10.1016/j.chemosphere.2011.04.072 [3] Carregosa, V., Velez, C., Soares, A. M. V. M., Figueira, E., & Freitas, R. (2014). Physiological and biochemical responses of three Veneridae clams exposed to salinity changes. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 177-178, 1–9. http://doi.org/10.1016/j.cbpb.2014.08.001