Effects of endocrine disrupters on sexual, gonadal development in fish

Steroid sex hormones play an important role in the sexual differentiation of fish. Thus, it is not surprising that chemical contaminants with steroid-like activities were considered as responsible for the unusual occurrence of gonadal intersex conditions and other gonadal aberrations in feral fish. In this review, we give an overview about field data and summarise and categorise experimental evidence that links disruption of gonadal development in gonochoristic fish to contaminations by endocrine disrupting chemicals. A comprehensive overview on laboratory studies using water-borne exposures and histopathological analysis is given. Parameters ranging from simple quantitative characteristics such as sex ratio, number of sex reversed fish, and gonadosomatic index (GSI) to detailed morphometric analyses have been considered. Categorisation of the data indicates 2 major groups of chemicals with apparently conserved effects across species, i.e. estrogenic/anti-androgenic or androgenic/anti-estrogenic compounds. Since gross morphological parameters and histological analysis are often the first parameters measured in field campaigns for sampling of feral fish, the review supports the critical evaluation of present and future field studies and the confirmation or rejection of causative links to exposure with endocrine disrupting chemicals. Furthermore, in combination with the analysis of molecular endpoints the processed data will be useful to deduce mechanistic information on potential endocrine disrupting compounds.