RESEARCH ARTICLE Sex steroid imbalances in the muricid Stramonita haemastoma from TBT contaminated sites M. Rossato 1 & I. B. Castro 1,2 & C. L. Paganini 3 & E. P. Colares 3 & G. Fillmann 1 & G. L. L. Pinho 1 Received: 14 July 2015 /Accepted: 7 December 2015 # Springer-Verlag Berlin Heidelberg 2016 Abstract Imposex incidence, organotin tissue levels, and sex steroid (free and esterified testosterone and estradiol) levels were assessed in Stramonita haemastoma from Babitonga Bay (Santa Catarina State, Southern Brazil). The imposex levels showed a reduction when compared to a previous eval- uation performed in the same area. In spite of that, the detected imposex incidence indicated the occurrence of tributyltin (TBT) inputs that were still able to produce endocrine disrup- tion in local gastropods. In addition, a high level of organotins was observed in tissues of imposexed females. These females also showed a hormonal imbalance, especially in the total testosterone/total estradiol ratio. These findings obtained un- der realistic field conditions suggest that the steroid pathway could be responsible by the imposex induction after exposure to TBT. In this case, measurements of sex steroid levels can be an additional evidence for monitoring sites and impose affect- ed gastropod populations. Keywords Butyltin accumulation . Endocrine disruptor . Hormonal disturbance . Imposex . Stramonita haemastoma . TBT Introduction Organotin compounds (OTs) are widely used as pesticides in agriculture, catalysts in the production of plastics (PCV) and stabilizers in industry (Omae 2006). However, the major ma- rine inputs of organotins—as butyltin derivatives (BTs)—use to come from antifouling paints (Morcillo and Porte 2000). These products have been used to protect ship hulls from fouling organisms. Although very effective against biofoul- ing, these antifouling paints are also highly toxic to non- target species (Fent 2006). The most well-known deleterious effect of tributyltin (TBT) exposure is called imposex, which is the development of a penis and/or vas deferens in female prosobranch gastropods (Smith 1971). Imposex, which is con- sidered to be one of the best documented examples of endo- crine disruption in wildlife (Matthiessen and Gibbs 1998), is unequivocally related to TBT exposure, with a direct cause- effect relationship (Horiguchi et al. 1995; Oehlmann et al. 1996; Horiguchi et al. 1997; Matthiessen and Gibbs 1998). Although the exact mechanism of TBT action on imposex development is still unknown (Lima et al. 2011), it is well known that is dose-dependent (Bryan et al. 1986; Sternberg et al. 2010; Matthiessen 2013). Therefore, imposex incidence has been widely used as a biomarker for TBT exposure. This phenomenon has been documented in coastal systems world- wide and often related to maritime traffic areas (Stewart et al. 1992; Titley-O’Neal et al. 2011; Castro et al. 2012a, b; Petracco et al. 2015). Due to its high toxicity to non-target organisms, the Inter- national Maritime Organization (IMO) banned the use of Responsible editor: Thomas Hutchinson * M. Rossato martina.rossato@gmail.com * I. B. Castro italobraga@gmail.com 1 Instituto de Oceanografia. Laboratório de Microcontaminantes Orgânicos e Ecotoxicologia Aquática, Universidade Federal do Rio Grande, C.P. 474, Rio Grande, RS 96203-900, Brazil 2 Departamento de Ciências do Mar, Universidade Federal de São Paulo, Santos, SP 11030-400, Brazil 3 Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, C.P. 474, Rio Grande, RS 96203-900, Brazil Environ Sci Pollut Res DOI 10.1007/s11356-015-5942-0