FORURENS: Bioaccumulation and endocrine disruptive effects of POPs in trout from Lake Mjøsa and an upstream refererence population

Endocrine disruption is of growing concern and of potential ecological relevance as we learn more about how xenobiotics disrupt the actions of hormones needed for developmental and reproduction in wildlife. Regulatory bodies worldwide are currently partic ularly focusing on endocrine disrupting chemicals (EDCs) that operate through discrete pathways within the sex-steroid and thyroid hormone systems. The risk assessment of EDCs is complicated by that thousands of current used and new chemicals present in t he aquatic environment seems to act as EDCs. One such multiple chemical exposure site is Lake Mjøsa. Some chemicals such as polybrominated diphenyls (PBDEs) are reported in levels in Mjøsa fish that exceed thresholds for endocrine disruption in experiment ally exposed fish. However, virtually nothing is known on the dimension of this problem in fish exposed to the multiple chemical mixture exposure situations in Lake Mjøsa. Thus, the present research proposal aims to provide baseline data on the occurrence of EDCs to determine whether endocrine disruption is likely to occur in Lake Mjøsa trout compared to reference fish. The chemical analyses will include a wide range of POPs and their metabolites. A novel input will be (anti)androgenic receptor (AR) activ ity bioassay measurements; and in combination a with (anti)estrogenic receptor (ER) assay and a fish transthyretin (TTR) assay the project will cover a broad spectrum of endocrine disruptive pathways. Tissue contaminant concentrations and in vitro bioassa y data will be tested for their relevance for predicting effects on in vivo biomarkers of endocrine function of the trout. Moreover, trough chemical analysis and by the use of novel Effect-Directed-analysis (EDA) bioassay system the relative importance of different disruptive chemicals in Lake Mjøsa trout will also be characterised.