Mental and physical stress of the Fukushima disaster evacuees as estimated by the measurement of urinary 8-hydroxy-2′-deoxyguanosine

Following the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, a number of evacuees were forced to live in temporary housing and suffered mental and physical stress. However, few reports have used objective or quantitative indicators to determine the evacuee's level of stress. The aim of the present study was to serially estimate the mental and physical stress of the evacuees from 2013 to 2015 by using the oxidative stress marker, urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG). A total of 773 evacuees from Namie town in Fukushima prefecture participated in the study. In the first year, 486 evacuees participated (age, 62.8±18.2 years; male/female, 217/269). Of these, 127 continually participated in the study for 3 years (age, 69.5±13.5 years; males/female 52/75) and 18.1% had no chronic disease after the first year. Urine samples were collected once per year. Urinary 8-OHdG was measured using immunochromatography and corrected by the concentration of urinary creatinine. For all the participants examined each year, mean values of urinary 8-OHdG significantly increased over time. For the 127 continual participants, mean values of urinary 8-OHdG were significantly higher in 2014 and 2015 than those in 2013. Age, gender and presence of chronic disease did not significantly influence the 8-OHdG values, suggesting that the stress level of the evacuees was not associated with these factors. The stress level of the individuals increased with the length of time spent living in the temporary housing. The evacuees in radiation disasters have different stressors from other natural disasters, which may accelerate mental and physical stress.