Environmental risk assessment is generally based on the comparison of the exposure concentration of a chemical with the sensitivity of the ecosystems for this chemical, The exposure to this chemical is often assumed to be constant and continuous, while in reality exposure is more likely to be variable and/or intermittent. Several approaches have been developed to account for the influence of exposure time on environmental effects. Time-to-event modelling is the most recent approach to include time in environmental risk assessment. This approach is applied in the DREAM model (Dose Related Effects Assessment Model), which is used to assess the environmental impact of produced mater discharges in the marine environment,