Association between radiation knowledge and risk perception among certified disaster prevention advisers ( <i>Bousaisi</i> ): a cross-sectional study

Certified Disaster Prevention Specialists (<i>Bousaisi</i>) serve as both at-risk residents and first responders in Japan. This study examined how attendance at radiation-preparedness seminars influences three domain-specific knowledge factors-basic radiation physics, genetic effects knowledge, and radiation protection misconceptions-and whether these domains mediate the changes in concerns about radiation's health effects. Between March and April 2023, the study surveyed 666 Certified Disaster Prevention Specialists via online and postal questionnaires. Eleven true/false knowledge items (excluding one inverse-worded item) were analysed with logistic regression, adjusting for age, sex, and other demographics, to test the association between seminar attendance and correct responses on each item. A multivariable linear regression was applied, using individual knowledge items, to predict a five-item factor score of health-effect concern. Exploratory factor analysis on polychoric correlations (oblimin rotation and parallel analysis) distilled those items the abovementioned three domains. A bias-corrected bootstrap mediation (5000 samples) was administered in lavaan to estimate how much of the seminar's effect was transmitted through each domain. At the baseline, correct rates for foundational physics items (time-distance-shielding, dose-unit quantification) exceeded 80%, whereas accuracy on epidemiological topics (occupational dose limits, DNA damage and repair, genetic-effect risks) was below 50%. Seminar attendance produced the largest gains in these underdeveloped items. In regression analyses, only genetic effects knowledge predicted lower health-effect concern (<i>b</i>= -0.52,<i>p</i>< 0.001). Mediation analysis demonstrated that reduced concern from seminar attendance operated exclusively through genetic effects knowledge (indirect<i>β</i>= -0.31,<i>p</i>= 0.01). Hence, radiation-preparedness seminars significantly improved both physics and epidemiological knowledge; however, only enhanced an understanding of genetic effects alleviated health-effect concern. Future curricula should retain a brief physics refresher while prioritising epidemiologically grounded instruction on genetic risks to optimise competence and confidence among community responders.