Chronic toxicity of endocrine disrupters to the crustacean Daphnia magna under complex exposure situations

Abstract

The aim of this thesis is to evaluate the chronic effects of endocrine disrupting chemicals (EDCs) to the crustacean Daphnia magna under complex exposure situations. It comprises four experimental studies, dealing with the toxicity of single substances as well as mixtures.It is evaluated whether additional life-history parameters, such as molting and embryo abnormalities, may indicate interferences of selected chemicals with ecdysteroid-related processes in the reproduction test with Daphnia magna improving an assessment of endocrine disrupters. A focus was set on structurally diverse demethylase inhibiting fungicides (DMIs), which were comparatively assessed with respect to their single substance toxicity as well as their joint toxicity to Daphnia magna. Here, the two concepts Concentration Addition (CA) and Independent Action (IA) were used to predict mixture toxicity based on single substance data across different endpoints and effect levels. The last experiment focused on the toxicity of binary combinations under conditions of sequential or simultaneous exposure and the predictive abilities of the two mixture toxicity concepts.