Postnuclear disaster evacuation and chronic health in adults in Fukushima, Japan: a long-term retrospective analysis

Abstract

Objective: Japan's 2011 Fukushima Daiichi Nuclear Power Plant incident required the evacuation of over a million people, creating a large displaced population with potentially increased vulnerability in terms of chronic health conditions. We assessed the long-term impact of evacuation on diabetes, hyperlipidaemia and hypertension.

Participants: We considered participants in annual public health check-ups from 2008 to 2014, administrated by Minamisoma City and Soma City, located about 10-50 km from the Fukushima nuclear plant.

Methods: Disease risks, measured in terms of pre-incident and post-incident relative risks, were examined and compared between evacuees and non-evacuees/temporary-evacuees. We also constructed logistic regression models to assess the impact of evacuation on the disease risks adjusted for covariates.

Results: Data from a total of 6406 individuals aged 40-74 years who participated in the check-ups both at baseline (2008-2010) and in one or more post-incident years were analysed. Regardless of evacuation, significant post-incident increases in risk were observed for diabetes and hyperlipidaemia (relative risk: 1.27-1.60 and 1.12-1.30, respectively, depending on evacuation status and post-incident year). After adjustment for covariates, the increase in hyperlipidaemia was significantly greater among evacuees than among non-evacuees/temporary-evacuees (OR 1.18, 95% CI 1.06 to 1.32, p<0.01).

Conclusions: The singularity of this study is that evacuation following the Fukushima disaster was found to be associated with a small increase in long-term hyperlipidaemia risk in adults. Our findings help identify discussion points on disaster planning, including preparedness, response and recovery measures, applicable to future disasters requiring mass evacuation.

Keywords: EPIDEMIOLOGY; PUBLIC HEALTH.

Figure 1

Geographical location of Minamisoma City and Soma City. The red circles show the geographical distribution of the health check-up participants in 2010, where the circles are proportional to the number of participants living in each district. The compulsory evacuation zone is divided into the (1) difficult-to-return zone (in green), where the annual dose of radiation is expected to be 50 mSv or more and people are not allowed to return home until at least March 2017; (2) no-residence zone (in yellow), where the annual dose is expected to be 20–50 mSv and people can temporarily return home to the area, but staying overnight is prohibited and (3) zone being prepared for lifting of the evacuation order (in blue), where the annual dose is expected to be <20 mSv and people can temporarily return home to the area, but staying overnight is prohibited.

Figure 2

Box plots for the distribution of radiation levels at non-evacuees’/temporary-evacuees’ residences by disease status. The bar represents the median radiation air dose rate, the box shows the 25th and 75th centiles, whiskers are 1.5 times the IQR, and outliers and extreme outlets are shown by dots and asterisks, respectively.