Diagnosing the governance gap: Technically informed public perception and institutional trust in microplastic regulation in Costa Rica

The rise of microplastics (MPs) and nanoplastics (NPs) in the environment and food systems alarms scientists, regulators, and the public. Effectively managing these pollutants requires an understanding of how different social groups perceive risks and engage with proposed solutions. Researching these perceptions is urgent in Costa Rica, which, despite its environmental leadership, lacks comprehensive regulations on MPs and NPs. This study presents findings from a national survey (n = 168) evaluating awareness, risk perception, behavioral intentions, trust in institutions, and support for regulatory measures regarding micro/nanoplastics. The survey targeted professionals in science, health, and engineering fields, representing a technically informed segment of the Costa Rican public. Accordingly, findings should be interpreted as technically informed public perception rather than general population opinion. Accordingly, findings reflect perceptions of a technically literate segment of the public and are not intended to be generalized to the national population. We explicitly call for probability-based, nationally representative surveys that prioritize rural, non-STEM, low-income, Indigenous, and coastal communities to validate and extend these patterns. Data were analyzed using descriptive statistics, cross-tabulations, and visualizations across 14 key questions. Findings show that 92.3 % of respondents were aware of MPs/NPs, and 88.7 % perceived them as a health risk. Regarding behavioral responses, 78.6 % expressed willingness to change personal consumption habits, while 76.2 % supported mandatory product labeling. Trust in governmental action was critically low, with only 3 % expressing confidence, 59.5 % expressing distrust, and 37.5 % expressing uncertainty. Moreover, 69 % had not noticed or were unsure about national initiatives on plastics governance. These percentages are non-overlapping indicators from different survey questions and therefore do not add to 100 %. However, together they reveal a coherent pattern of high awareness and concern, strong support for regulatory measures, and very low institutional trust. This indicates a motivated public perceiving a credibility gap in regulations. This research underscores the importance of public perception studies in shaping participatory environmental governance. Identifying trust gaps and behavioral thresholds can guide risk communication, labeling frameworks, and policy development. The findings reveal a governance deficit in plastic risk management, where high scientific awareness does not align with institutional credibility. Policy reform should engage the informed public as a strategic ally rather than a passive recipient of regulation. Policy reform should engage the informed public as a strategic ally while commissioning representative follow-up surveys across non-STEM and underserved populations to ensure equitable, evidence-based microplastic governance. This focus preserves comparability with international perception studies while clarifying that results reflect a high-literacy subset of Costa Rican society. • Costa Rica survey of 168 STEM professionals on MP/NP risk; findings reflect a technically literate subset only. • Awareness 92.3% and concern 86.3% for MP/NP indicate a technically informed, risk-sensitive cohort. • Only 3% trust institutions, signaling a severe legitimacy deficit. • 76.2% favor product labeling, indicating readiness for regulatory transparency. • Findings reveal a governance gap: informed willingness vs. invisible or fragmented institutional action.