The report provides the comprehensive risk assessment of the substance Benzyl Butyl Phthalate. It has been prepared by Norway in the frame of Council Regulation (EEC) No. 793/93 on the evaluation and control of the risks of existing substances, following the principles for assessment of the risks to humans and the environment, laid down in Commission Regulation (EC) No. 1488/94. Part I – Environment. This part of the evaluation considers the emissions and the resulting exposure to the environment in all life cycle steps. Following the exposure assessment, the environmental risk characterisation for each protection goal in the aquatic, terrestrial and atmospheric compartment has been determined. The environmental risk assessment concludes that there is concern for surface water (including sediment) and the terrestrial compartment from some use categories and there is a need for further information and for testing (long-term fish study on reproductive and endocrine effects).