A short-cut method for environmental assessment during process development is presented. The method can deal with data uncertainties in early phases, includes all relevant environmental impacts, and is simple and easy to apply. Therefore, it can be used in early phases of process development. The environmental relevance of each substance is represented by the Environmental Factors. These factors are derived from 14 impact categories, where each compound is classified using an ABC methodology. The impact categories are then grouped into six impact groups: Resources, Grey Input, Component Risk, Organisms, Air and Water/Soil. From these, input and output environmental factors are deduced. This factor is combined with mass balance data to yield a number of indices that can be used to optimize the environmental performance of a process in an integrated manner. The method is applied to three case studies: a comparison of chemical and biotechnological production of 6-aminopenicillanic acid, a comparison of two process alternatives in the enzymatic production of alpha-cyclodextrin and the development of a new process for the fermentative production of pyruvate. (C) 2004 Society of Chemical Industry.