Traditional as well as biotechnological processing of a heterogeneous adduct like coal will lead to a complex mixture of various unknown compounds, The implementation of a chemical-by-chemical approach as made possible by the development of more specific chemical and physical analytics is only a limited tool to protect the environment against hazardous discharges. Therefore, investigations carried out were focused on selection, adaption and validation of bioassays suited for a sensitive and reproducible valuation of coal relevant products. Bioassays with organisms representing different trophic levels like bacteria, daphnia and algae were used for determination of ecotoxicological/toxicological effects. The obtained results show the suitability of these bioassays for the valuation of ecotoxicological effects of coal-relevant substances and different model compounds similar to microbial transformation/conversion products of coal.