Radiation knowledge, risk literacy, and concern about heritable effects: a cross-sectional study in Fukushima and the Tokyo metropolitan area

Public concern persists about the heritable effects of radiation following the Fukushima Daiichi Nuclear Power Station accident, despite scientific consensus indicating no detectable increase in such effects. This study examined how radiation-related knowledge and multidimensional risk literacy relate to concern about heritable effects, and explored the cognitive mechanisms underlying this concern, among residents of Fukushima Prefecture and the Tokyo metropolitan area (the seven prefectures of the Kanto region).

A web-based cross-sectional survey was conducted in September 2023 among 1,529 residents of Fukushima Prefecture and the Tokyo metropolitan area. Radiation-related knowledge and risk literacy were assessed using five structured items and a validated 24-item scale comprising six subscales, respectively. Hierarchical logistic regression and exploratory statistical mediation analyses were used to identify independent predictors of concern and to examine the mediating role of risk literacy.

Fukushima residents demonstrated higher radiation-related knowledge, whereas Tokyo residents reported greater concern about heritable effects. In the multivariable model, higher knowledge (odds ratio = 0.77, 95% confidence interval: 0.69-0.85; not significant when the two items closely paralleling the outcome were excluded) and higher scores on several risk literacy subscales, most notably cognitive bias awareness, were independently associated with lower concern. This residence-concern association was somewhat attenuated but persisted after adjustment for these factors (odds ratio = 1.42, compared with 1.53 before adjustment). Mediation analysis indicated that approximately 29% (95% CI [20.1%, 42.2%]) of the association between knowledge and concern was statistically mediated by risk literacy, with the remainder representing an association between knowledge and concern independent of risk literacy.

Radiation-related knowledge and multidimensional risk literacy were independently associated with lower concern about heritable effects, and were associated with part of the geographical disparity in concern between Fukushima and Tokyo residents. Because these factors act as complementary rather than interchangeable determinants, reducing unwarranted concern may require not only correcting factual misconceptions but also cultivating public capacity for structured risk reasoning, particularly in regions beyond the directly affected area.