Public defence: Ayse Kaplan Sarisaltik

Plastics are deeply integrated into everyday social practices such as hygiene, childcare, cooking and leisure. While plastics provide convenience and functionality, their widespread use contributes to significant environmental challenges. Understanding plastic consumption therefore requires attention not only to individual choices, but also to the social practices and systemic relations that shape everyday life.

This thesis explores how a combined approach drawing on systemic design and social practice theory can help identify intervention areas to support more sustainable plastic consumption in everyday life.

The research focuses particularly on menstruation practices as a way of examining the broader dynamics of plastic consumption. Menstruation represents a relevant empirical context because it involves intimate bodily experiences, social norms, infrastructures and widely used disposable products that rely heavily on plastic materials.

Through literature reviews, focus groups, visual interviews and workshops, the study investigates how plastic consumption becomes stabilised within everyday practices and how alternative configurations may emerge.

The findings show that plastic consumption is embedded in interconnected practices and wider sociotechnical systems. Consequently, interventions cannot rely on single solutions but require multiple and interacting measures.

By bringing systemic design and social practice theory into dialogue, the thesis contributes new methodological and theoretical insights for researchers, designers, industry actors and policymakers working to support sustainability transitions.

Rather than framing plastic reduction solely as an issue of individual responsibility or technological substitution, the research emphasises the importance of systemic, relational and reflexive approaches to long-term transformation.