Making Microplastics Matter: Classification, Politics and the Lives of Microplastics as Environmental Objects.

How do emerging environmental phenomena become actionable amid scientific uncertainty and public urgency? This article argues that to understand how microplastics become governable, we must study classification as a central site where matters of fact, concern, and care are composed. Drawing on comparative assemblage ethnography across scientific conferences, public debates, and European regulatory processes, we trace how microplastics are enacted as epistemic, public, and regulatory objects. In scientific practice, object-centered classifications aim at rendering heterogeneous particles measurable and comparable. In public arenas, labeling condenses plurality into a recognizable and affectively charged issue. In regulatory contexts, source-centered and legally operational categories reorganize the phenomenon into governable segments. These are not translations of a stable object-microplastics-but distinct enactments shaped by different evidentiary standards and institutional constraints. The case shows that classification under conditions of ontological instability does not necessarily lead to closure but enables coordination. We show how governance materializes through classificatory infrastructures that stabilize relations between fact, concern, and care without resolving epistemic indeterminacy. Classification is a political technology through which environmental objects are rendered actionable in the absence of settled knowledge.