Aquatic Toxicology 66 (2004) 279–292 The endocrine disrupting effect of municipal effluent on the zebra mussel (Dreissena polymorpha) Brian Quinn a,e,∗ , Francois Gagné b , Mark Costello c , Craig McKenzie d , Jim Wilson e , Carmel Mothersill a a Radiation and Environmental Science Centre, Dublin Institute of Technology, Kevin St., Dublin 8, Ireland b Environmental Canada, St. Lawrence Centre, 105 McGill St., Montreal, Que., Canada H2Y 2E7 c Huntsman Marine Science Centre, St. Andrews, NB, Canada E5B 2L7 d Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland e Zoology Department, Trinity College, Dublin 2, Ireland Received 11 November 2002; received in revised form 6 February 2003; accepted 24 October 2003 Abstract Municipal effluents have been shown to contain a cocktail of endocrine disrupting chemicals (EDCs). The estrogenic effect of these effluents has been demonstrated on both vertebrate and invertebrate species by the feminisation of the exposed males. This effect was investigated on the freshwater zebra mussel (Dreissena polymorpha) after exposure to tertiary treated effluent from a municipal sewage treatment works (STW). Mussels were exposed to the effluent in situ for 112 days during gametogenesis (December to mid-March). Levels of vitellin (Vn)-like proteins (the major protein found in oocytes) were measured indirectly using the alkali-labile phosphate (ALP) technique and confirmed by gel electrophoresis. Significant increases (P< 0.05) in Vn-like proteins were found in both male and female mussels after exposure to the effluent, indicating that endocrine disruption (ED) had occurred. Using High-performance thin layer chromatography (HPTLC) levels of the mussels main steroid, cholesterol were found to more than double after effluent exposure. General physiological (survival, condition, etc.) and histological effects were also investigated. Histological effects observed included a large increase in interstitial tissue between the seminiferous tubules of the gonad in male mussels exposed to effluent. Effluent samples were tested for estrogenic compounds using the toxicity identification and evaluation method (TIE). A complex mixture of compounds with estrogenic activity was found with 17-estradiol, 17-ethynlestradiol and bisphenol A accounting for the majority of the effluents estrogenic activity. Results indicate that the zebra mussel is a suitable bioindicator of endocrine disruption in freshwater environments. © 2003 Elsevier B.V. All rights reserved. Keywords: Zebra mussel; Endocrine disruption; Municipal effluent; Vn-like proteins ∗ Corresponding author. Tel.: +353-1-514-496-7104; fax: +353-1-514-496-7398. E-mail address: brian.quinn@ec.gc.ca (B. Quinn). 1. Introduction In Ireland municipal sewage effluent has been re- sponsible for the majority of moderate and serious pollution incidences in the freshwater environment (EPA, 2000). For a long time municipal effluents have 0166-445X/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.aquatox.2003.10.007