MARTINI, G.A.FRANÇA, D.D.SOARES, W.A.A.TAKEDA, S.H.K.QUINAGLIA, G.A.SATO, M.I.Z.ROGERO, J.R.2017-12-062017-12-062017MARTINI, G.A.; FRANÇA, D.D.; SOARES, W.A.A.; TAKEDA, S.H.K.; QUINAGLIA, G.A.; SATO, M.I.Z.; ROGERO, J.R. Four years of estrogenic activity assessment in surface waters of São Paulo State, Brazil. <b>Applied Research in Toxicology</b>, v. 2, p. 32-32, 2017. suppl. 1. Disponível em: http://repositorio.ipen.br/handle/123456789/28109.2359-4721http://repositorio.ipen.br/handle/123456789/28109Endocrine disrupting chemicals (EDCs) have the ability to alter the endocrine system of organisms. Such compounds are present in several industrial and domestic activities and reach the aquatic environment via wastewater discharges or agricultural surface runoff. The aim of this study was to determine the overall estrogenic activity of surface waters of São Paulo State, Brazil. For this purpose, 10 sites from the routine Surface Water Quality Program of CETESB were selected that were already surveyed for physical, chemical and biological variables from 2013 to 2016. Samples were extracted in solid phase and tested for estrogenic activity using bioluminescent yeast estrogen assay (BLYES). Results were expressed in 17-estradiol equivalent quotient (EEQ). Estrogenic activity was below the limit of quantification (0.1 EEQ) in 31.7% of 227 samples. All sites presented estrogenic activity at least once. The results have shown the presence of estrogenic activity in a range from 0.11 to 26.6 EEQ in the sampling sites in four years of study. Statistical analysis showed a positive correlation between estrogenic activity and the biochemical oxygen demand performed in the samples, indicating that this activity detected in most sites is related to wastewater discharges. Due to the presence of estrogenicity higher than 5.0 EEQ in a few sampling sites, further chemical analyses and other bioassays are recommended in order to provide a better understanding of the estrogenic activity present at these sites.32-32openAccessResumos em periódicos2suppl. 1https://orcid.org/0000-0002-2517-7772