Chemical and biological characterization of estrogenicity in effluents from WWTPs in Ria de Aveiro (NW Portugal). 
Effluents from wastewater treatment plants (WWTPs) are responsible for the input of estrogenic contaminants into aquatic ecosystems, leading to widespread effects in wildlife.  In the present work, levels of estrone (E1), 17alpha- and 17beta-estradiol (E2), 17alpha-ethinylestradiol (EE2), bisphenol A (BPA), and nonylphenol (NP) were quantified in effluents from WWTPs located in Ria de Aveiro (NW Portugal), as well as in the final effluent discharged into the Atlantic Ocean through the S. Jacinto submarine outfall.  Reference sites, located at the entrance of the estuarine system and at the seaside, were also included.  Samples were collected under summer (June 2005) and winter (February 2006) conditions.  For the summer survey samples, estrogenicity and androgenicity were evaluated using the yeast estrogen screen (YES) and the yeast androgen screen (YAS) assay.  Estrone levels varied from 0.5 to 85 ng/L in the summer survey and between <LOD (limits of detection) and 43 ng/L in winter; estradiol levels ranged from <LOD to 9.2 ng/L in summer and were always <LOD in the winter survey; EE2 levels were always <LOD for both surveys.  NP concentrations ranged from 75 ng/L up to 2,350 ng/L in summer and from 10 to 2,410 ng/L in winter; BPA levels varied from 2.8 to 897 ng/L in summer and from 2.6 up to 316 ng/L in winter.  Biological assays disclosed estrogenic levels at reference sites lower than the ones reported to pose risk for wildlife.  However, the S. Jacinto outfall effluent released high concentrations of NP and BPA into the marine environment.