Are We Speaking the Same Language? Recommendations for a Definition and Categorization Framework for Plastic Debris

ABSTRACT: The accumulation of plastic litter in natural
environments is a global issue. Concerns over potential
negative impacts on the economy, wildlife, and human health
provide strong incentives for improving the sustainable use of
plastics. Despite the many voices raised on the issue, we lack a
consensus on how to define and categorize plastic debris. This
is evident for microplastics, where inconsistent size classes are
used and where the materials to be included are under debate.
While this is inherent in an emerging research field, an
ambiguous terminology results in confusion and miscommunication
that may compromise progress in research and
mitigation measures. Therefore, we need to be explicit on
what exactly we consider plastic debris. Thus, we critically
discuss the advantages and disadvantages of a unified terminology, propose a definition and categorization framework, and
highlight areas of uncertainty. Going beyond size classes, our framework includes physicochemical properties (polymer
composition, solid state, solubility) as defining criteria and size, shape, color, and origin as classifiers for categorization.
Acknowledging the rapid evolution of our knowledge on plastic pollution, our framework will promote consensus building
within the scientific and regulatory community based on a solid scientific foundation.