Christopher, Emily A.Bouwmeester, HansChristopher, Emily A.Coffin, ScottHaase, AndreaLane, TaylorLegler, Juliette2026-07-132026-07-132026Koelmans, A.A., Bouwmeester, H., Christopher, E.A., Coffin, S., Haase, A., Lane, T., Legler, J., Vermeulen, R., Visser, M., Vogel, A. and Wardani, I., 2026. Towards regulatory readiness: evaluating frameworks for microplastic health risk assessment. Microplastics and Nanoplastics, 6(1), p.40.https://doi.org/10.1186/s43591-026-00199-0https://hdl.handle.net/10566/24920Micro- and nanoplastic particles (MNPs) have emerged as pollutants of high public concern. Assessing and managing the risks of these particles remains challenging for several reasons. A long-term goal is to establish a comprehensive risk-governance framework that includes risk framing, scientifically sound risk assessment that accounts for human and environmental safety, evaluation, and risk management/decision making. A realistic short-term goal is to develop a comprehensive human health risk assessment framework (RAF). Very recently, RAFs for evaluating the human-health risks of MNPs have become available; however, comparative analyses of these frameworks are lacking. Here, we discuss six established frameworks to assess their technological and regulatory readiness. We begin by proposing nine technical criteria that a risk-assessment framework should meet to inform policy and action. These include the degree of quantifiability of outputs; the provision for systematic evaluation of the quality of input data; the consistency between exposure and effect data with respect to underlying mechanisms; the extent to which the complexity and diversity of environmentally realistic microplastics are addressed; readiness for integration into existing regulatory approaches; and the extent of real-world implementation to date. We discuss the specific strengths of each framework and recommend combining them into a single overarching framework that integrates these strengths.enExposure assessmentHazard assessmentHuman health risk assessmentMicroplasticsNanoplasticsArticle