| Summary: | Synthetic hormones are a group of pharmaceuticals used for various human and animal treatments. However, consumption and disposal of these substances have also given rise to negative effects and environmental problems for organisms in the wild which is why these substances have been classified as estrogenic endocrine-disrupting chemicals (EDCs). Studies on the estrogen receptors (ers) and their genes are of particular interest when investigating emerging negative effects from estrogenic EDC contaminants. In vertebrates, the ers are well conserved between organisms and regulate activation and deactivation involved for example in growth, reproduction and development in both males and females. The initial aims of my research presented in this thesis were to show how the duplicated er genes in vertebrates, by studying fish and salmonid species in particular, are distributed, activated or disrupted by both ecological and pharmaceutical challenges. I have worked with three different fish species: Atlantic salmon (Salmo salar); brown trout (Salmo trutta); and roach (Rutilus rutilus) sampled from natural populations in the wild. I show that there is a complex interaction between estrogens and its receptors, depending on which tissues and life stages are investigated. I have also identified multiple ers in salmonids, which could affect their sensitivity to EDC exposure. In the framework of how 17α-ethinylestradiol (EE2) affects fish and the environment we linked exposure of EE2 to changes in behavior and gene expression and as such the consequences it might have for the structure and function of an ecosystem. Because of the recent focus on technical solutions for the removal of pharmaceutical EDCs in the environment a complementary aim was to investigate whether increased knowledge regarding the disposal and usage of EDCs, so called upstream work, could lower use of and prescriptions for the human female contraception EE2. For this I assessed the societal awareness among the main prescribers and decision makers in Sweden ...
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