Beyond annual dose: Assessing lifetime cancer risk from dietary radiocesium exposure and public risk-perception gaps in Japan.

Radiocesium in food poses an ongoing challenge in environmental health risk assessment. Annual dose compliance (1 mSv/year) is essential for radiological protection but may not reflect cumulative lifetime cancer risk (LCR) under chronic exposure or corresponding public risk perceptions. We developed an integrated radiological risk assessment framework to evaluate dietary radiocesium-related health risks and determine whether these estimates align with public risk perceptions. We estimated prefecture-level LCR and risk-perception gaps through multilevel regression and poststratification using a nationwide survey in Japan, together with food-monitoring data on radiocesium concentrations. The annual dietary radiation dose was well below the 1 mSv/year benchmark, while modeled mortality and morbidity LCRs remained above 10-5, ranging from 1.84 × 10-5 to 1.37 × 10-4 and from 2.70 × 10-5 to 2.02 × 10-4, respectively. The high-risk prefectures, particularly in Tohoku identified in spatial analyses, warrant prioritized monitoring. Agricultural products were the dominant exposure pathway, accounting for approximately 55.0-64.5% of the estimated LCR. Estimated risk tended to exceed perceived risk in northern Japan, indicating a need for proactive risk control, whereas perceived risk tended to exceed estimated risk in central Japan, suggesting a greater need for targeted communication. Our framework supports region-specific monitoring and communication by considering the LCR alongside annual dose metrics.