Risk assessment approaches within the regulatory framework of the European Union (EU) based on single species tests were compared to those using data from terrestrial model ecosystems (TMEs). In a case study with the fungicide carbendazim, single species data led to ratios of the predicted environmental concentration (PEC) and predicted no effect concentration (PNEC) of above 1000, depending on available data and related assessment factors, indicating concern for the terrestrial environment. Considering the high degree of realism of the TME studies with multiple endpoints measured, but also residual uncertainty related to higher variability of endpoints, an assessment factor of 5 was applied on TME data. The most sensitive reliable endpoint was earthworm biomass. With the TME studies yielding slightly higher effect thresholds compared to laboratory data, and due to the lower assessment factor, the PEC/PNEC ratio was lowered to 5. This means that there would be concern for high application rates of carbendazim.