Data Availability and the Application of Plastic Additive Flows in Life Cycle Assessments (LCAs) of Plastics for the Circular Economy

To facilitate the transition to a circular plastic economy, and to promote sustainable plastic production and usage, it is imperative to account for the impacts of plastics throughout their life cycles, in both current linear scenarios and potential circular systems. This accounting must encompass the effects of additives, i.e., organic and inorganic chemicals and fillers that are essential to the production of plastics. Alongside baseline polymers, additives represent a substantial source of uncharted impacts in plastic life cycles, as well as littering and microplastic emissions. Plastic additives, like many chemicals, are commonly underreported, rendering their impact accounting in these life cycles challenging.

Approaches such as life cycle assessments (LCAs) have been proposed as means to incorporate accounting for additive impacts in plastic life cycles and prospective circular economy scenarios. However, before implementing these approaches, it is essential to:

• Understand how additives are included in LCAs with respect to methodological applications and a discussion of their impacts.
• Assess what data is needed, and what is available in LCA databases, to support the inclusion of additives in plastic LCAs.
• Explore how existing data sources, models, and methods can be used in accounting for additives in circular plastic scenarios despite known barriers.
• Develop methods and tools that can better facilitate the transparency of additives in plastic LCAs and inform decision-makers utilizing these LCAs about the role of additives in plastic LCAs.

This PhD research aims to develop and apply tools and methods which incorporate emerging knowledge on additives and increased transparency of their modelling within plastic LCAs for linear and circular futures. This is done to explore how inclusion of additives in plastic LCAs can benefit planning for the circular plastics transition.

In this synopsis, the introduction contextualizes the incorporation of additives in plastic LCAs within the circular economy transition framework. In Chapter 2, background information on the roles and functions of additives in plastics is provided to emphasize primary challenges and recent developments in their inclusion in LCAs. Chapter 3 presents the research design and rationale, whilst Chapters 4 through 6 delve into the research questions, offering key findings, and discussing the implications of the peer-reviewed publications developed during this PhD research. Finally, Chapter 7 discusses the overall implications of the research and reflects on the application of the research method. Chapter 8 presents the conclusions and findings based on answering the research questions.

In all this research resulted in the development of several tools and methods aimed at improving the inclusion of additives in the LCA of circular plastics.
These tools include:

• A disclosure framework for additives discussed in scientific publication and include additives within the conducted LCA based off OECD and ECHA practices.
• A tool to help practitioners determine which additives have data available in the major LCA databases. This tool also links available data to state-of-the-art knowledge on the common usage of these additives in plastics.
• A discussion framework to help practitioners and decision-makers decide when additives should be included or cut off and how to disclose their presence in future LCAs.
• A proposed methodology to improve the use of statistical proxy modelling which enables different levels of additive data transparency and inclusion.

These tools and methods were developed in answer to barriers and challenges identified in pursuit of the research questions and are supported by the publications accompanying this synopsis.

The research conducted in this PhD contributes to the understanding and development of methods and tools to enhance plastic additive inclusion in the field of LCAs by providing valuable data and insights. The methods, tools, and approaches proposed herein facilitate the inclusion and accounting of additives in plastic LCAs, thereby enhancing the robustness of these studies. This, in turn, aids decision-makers in gaining a comprehensive understanding of the holistic impacts of plastics in various life cycles.