The study discusses the challenges posed by substances of concern (SoCs) in products, emphasizing the need to address them within the framework of a circular economy (CE). It introduces the Safe and Circular Design (SCD) method as a potential solution but notes its lack of practical testing. The study focuses on implementing the SCD method in addressing indium tin oxide (ITO) within a liquid crystal display (LCD) monitor, highlighting difficulties due to limited data on SoCs and strategies for their management. An ex-ante life cycle assessment (LCA) compares ITO and an alternative, revealing environmental impacts and challenges in evaluating toxic trade-offs. The application of the SCD method to the LCD case identifies insights and challenges, emphasizing the importance of data availability and multidisciplinary collaboration for safer and sustainable product development. The study recommends refining the SCD method and conducting further case studies to assess its effectiveness across different scenarios. It underscores the need for enhanced data transparency and collaboration among stakeholders to advance safe and sustainable product design.