Policy makers and scholars from the social sciences encourage innovators to consider broader social and ethical aspects for the responsible development and deployment of new and emerging scientific and technological innovations. Innovators can partly answer this call by conducting product Life Cycle Assessments (LCAs). Yet, how LCAs can help shape responsible innovation remains unclear. This study investigated how innovators actually deploy LCAs, particularly in relation to responsible innovation practices.In this study, the method of Midstream Modulation, as a form of Socio-Technical Integration Research, is used to observe and interact with researchers on the working floor, to learn how they shape their decisions. These observations are at the basis of five presented narratives that highlight how LCAs are developed and used in corporate research and development practices. These narratives are subsequently analyzed in relation to responsible innovation development.The results show that, as is proposed in literature, LCAs can indeed be used to quantify the level of environmental impact and as such, can be useful decision aids to select the best, or most sustainable, products and/or production processes. However, the results of this study also show that there are several aspects that cannot be covered just by doing LCAs, yet these aspects are still important for the responsible development and deployment of innovations. In fact, some aspects regarding LCAs cause confusion rather than clarification in relation to responsible innovation development. This paper also shows that through interactions with a critical outsider, through a method such as Midstream Modulation, scientists can learn to become more reflective on their LCA practice, allowing them to include the broader socio-ethical context of innovations on top of calculable environmental impact. This help them answer policy calls for socially responsible innovation, and at the same time contribute to an organization's image in terms of corporate social responsibility.