In this study the effects of tributyltin (TBT) and cadmium (Cd) were tested on the freshwater arthropod Chironomus riparius (Diptera) in life-cycle experiments. To this end, the OECD guideline 218 was extended with reproduction relevant parameters (e.g. number of fertile egg masses per female). Based on these reproduction data the number of larvae for next generation and the population growth rate were calculated. Experiments were performed using environmentally relevant concentrations of the test substances in the sediment (nominal ranges: 50-200 micro g Sn/kg and 0.2-2.1 mg Cd/kg, on a dry weight basis). Quartz sand was used as sediment in order to develop a test system for a following research project, focusing on the effects of TBT and Cd as model stressors on C. riparius populations in multi-generation studies. Both model stressors caused significant effects on development and reproduction of C. riparius. Larval mortality proved to be a sensitive parameter and a clear concentration-response relationship was observed with a significant increase (P < 0.001) at the highest TBT concentration and at a Cd concentration of 1.17 mg Cd/kg dw (P < 0.05). The two highest TBT concentrations emergence was significantly (P < 0.05) delayed compared to the solvent control. For Cd a clear prolonged average main emergence interval was observed, but not for TBT. TBT and Cd inhibited also oviposition. These effects resulted in a concentration-depended reduction of the population growth rate.

Purpose There is a growing concern regarding the effects of endocrine disrupting compounds on humans and wildlife. Since some of them have the ability to bind to particulate matter, high concentrations can be reached in sediments of surface waters. The objective of this study was an assessment of 50 sediment samples from predominantly small rivers in the German federal state of Hesse with emphasis on endocrine activity. Materials and methods The freshwater mudsnail Potamopyrgus antipodarum was exposed to whole sediments for 28 days with a subsequent evaluation of embryo production. Additionally, in vitro screens with sediment eluates for the detection of estrogenic (yeast estrogen screen, YES) and androgenic (yeast androgen screen, YAS) activities were conducted. Biotest results were compared with chemical analytical data (metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organotin compounds), which were available for about half of the studied sites. Results and discussion Seventy-eight percent of the sediments caused a significantly increased reproduction in the Potamopyrgus test, 66% were active in YES, and 68% were active in YAS. More than half of the sediments caused an increased reproduction in vivo and concurrently showed an estrogenic activity in vitro. No significant correlations could be established between biotest results and chemical analytical data. ConclusionsThe results indicate that sediment contamination with endocrine active compounds is widespread, plays an important role in aquatic ecosystems, and should be the subject of further ecotoxicological investigation.

The objective of this study was a sediment assessment of predominantly small rivers in the German federal state of Hesse. For this purpose, sediment samples were taken at 50 study sites with different contamination levels. The benthic invertebrates Chironomus riparius (Diptera) and Lumbriculus variegatus (Oligochaeta) were used as test species and exposed to whole sediments in chronic laboratory experiments. The bioassays were carried out on the basis of OECD guidelines 218 and 225 for the testing of chemicals. For about 50 % of the study sites chemical analytical data for pollutants from environmentally important substance classes like metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organotin compounds were available. These data were used to analyze correlations between effects in the bioassays and measured chemical contaminations at sampling sites. For 22 % of the sediments ecologically relevant adverse effects were observed. In the majority of these cases effects occurred in only one of the biotests, and only one sediment sample exerted a negative effect on both test organisms. There was no significant correlation between biological responses and chemical data considering substance classes. However, there was a weak positive correlation between arsenic concentration and both worm number and worm biomass as well as a weak positive correlation between single PAHs and worm biomass. In some sediment tests elevated ammonia concentrations occurred in the overlying water so that an influence of these partially toxic concentrations on the test results cannot be ruled out.

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