Introduction
Supporting the transition to safer and more sustainable chemicals and materials requires minimizing the chance of a regrettable substitution. Alternatives assessment is defined as a “process for identifying and comparing potential chemical and non-chemical alternatives [e.g., materials, products, technologies] that could replace chemicals of concern on the basis of their hazards, performance, and economic viability” (National Research Council, 2014). An array of plastic products has been presented as potential alternatives to chemicals of concern in recent alternatives assessments. For example, Washington State Department of Ecology examined other plastics as alternatives to per and polyfluorinated alkyl substances (PFAS) coatings used in food packaging applications (Washington State Department of Ecology, 2022). The assessment noted the potential for polymeric materials to form microplastics when considering exposure pathways. This potential to form microplastics led assessors to conclude that not enough information was available to complete the exposure assessment and therefore the plastic alternatives were discounted from further consideration. This Washington alternatives assessment identified a gap in the field—existing alternatives assessment frameworks and guidance documents have not outlined methods for addressing microplastic formation and associated contamination. Microplastics can either be intentionally added to products, or generated during manufacturing, use, or as plastic products degrade during end of life. Intentionally added microplastics, such as the use of microbeads in personal care products and cosmetics, have been banned or are expected to be banned in multiple jurisdictions, including in the United States (US) and the European Union (EU) (114th US Congress, 2015). Although there are additional industrial uses of intentionally added microbeads that remain unregulated, impacts associated with unintentionally generated microplastics are gaining recognition given the significant production and consumption of plastics globally (OECD, 2022). The Sustainable Chemistry Catalyst at the University of Massachusetts Lowell was asked by the Washington State Department of Ecology to propose considerations for addressing unintentionally generated microplastics within alternatives assessments. To support these considerations, this white paper first provides a brief primer on microplastics. Next, the paper outlines specific considerations for a model alternatives assessment framework, the Interstate Chemicals Clearinghouse’s (IC2) Alternatives Assessment Guide (IC2 Guide, 2017). Although this paper focuses on adaptations to the IC2 Alternatives Assessment Guide, suggested approaches for addressing microplastics formation are generalizable to all alternatives assessment frameworks. Recommended considerations focus on specific components within the alternatives assessment approach including: (a) identifying potential alternatives, (b) hazard assessment, and (c) comparative exposure assessment. These infuse lifecycle thinking within these assessment components versus relegating considerations for microplastics to a separate lifecycle considerations module, which is considered optional in several alternatives assessment frameworks, including the IC2 Alternatives Assessment Guide. Recommendations in this white paper were informed by a literature review on microplastics and consultation with alternatives assessment and microplastics experts. The literature review is presented in Appendix A; readers are encouraged to consult this Appendix for additional background information.