Reduction in live births in Japan nine months after the Fukushima nuclear accident: An observational study.

Alfred Körblein,Tim A Mousseau

doi:10.1371/journal.pone.0242938

Abstract

BackgroundAfter the Chernobyl accident on 26 April 1986, a drop in birth-rate was found in several European countries in the first quarter of 1987. The objective of the present study was to investigate whether a similar drop in live births occurred in Japan after the Fukushima nuclear accident.Data and methodsA study region was defined consisting of Fukushima prefecture plus 10 nearby prefectures. The observed monthly numbers of live births (LB) in October 2011 through December 2012 were compared with the predicted numbers determined from the trend of live births in the remaining months from January 2006 through December 2018. The study region was divided into Fukushima plus three adjacent prefectures (Area A, assumed effective mean dose in the first year 1 mSv) and seven surrounding prefectures (Area B, 0.5 mSv). The rest of Japan (Area C) served as the comparison (control) region (0.1 mSv). A combined regression of live births (LB) in areas A, B, C was conducted with individual trend parameters but common parameters for monthly variations.ResultsIn the study region as a whole (areas A and B combined) a highly significant 9.1% (95% CI: -12.2%, -6.0%) drop in LB was found in December 2011. Reduced numbers of live births were also observed in October-November 2011 (-3.3%, p = 0.006), i.e. in births exposed early in pregnancy. In the second quarter of 2012, i.e. in live births conceived more than 3 months after the Fukushima accident, the decrease was greater (-4.3%, p < 0.001) than in the first quarter (-1.6%, p = 0.11). i.e. in those conceived within the first three months after the accident while no significant decrease was detected in the third (-0.7%, p = 0.44) and fourth (-0.5%, p = 0.62) quarters. The effect in Dec 2011 was greater in Area A with -14.0 (-17.6, -10.3) % than in Area B with -7.8 (-11.1, -4.5) % and non-significant in Area C with -1.3 (-4.2, +1.6) %, p = 0.38. The combined regression of the data in areas A, B, and C found a highly significant association of the effect in December 2011 with radiation dose. Conclusion: It is suggested that the observed drop in LB in December 2011 may reflect early deaths of the conceptus from high radiation exposure following the triple meltdown at the Fukushima Daiichi nuclear power plant on March 12–15, 2011.

Highlights

After the Chernobyl nuclear accident on 26 April 1986, a drop in birth rates was found in the first three months of 1987 (i.e. 9 ± 1 months after the accident), in several European countries, including Greece [1], Italy [2], Sweden [3, 4], Norway [5], Finland [6, 7], and Hungary [8]
In the study region as a whole a highly significant 9.1% drop in live births (LB) was found in December 2011
In the second quarter of 2012, i.e. in live births conceived more than 3 months after the Fukushima accident, the decrease was greater (-4.3%, p < 0.001) than in the first quarter (-1.6%, p = 0.11). i.e. in those conceived within the first three months after the accident while no significant decrease was detected in the third (-0.7%, p = 0.44) and fourth (-0.5%, p = 0.62) quarters

Summary

Introduction

After the Chernobyl nuclear accident on 26 April 1986, a drop in birth rates was found in the first three months of 1987 (i.e. 9 ± 1 months after the accident), in several European countries, including Greece [1], Italy [2], Sweden [3, 4], Norway [5], Finland [6, 7], and Hungary [8]. Studies of LB were conducted in Japan after the Fukushima nuclear accident on 12–15 March 2011 [9,10,11]. Kurita [11] studied birth rates in Fukushima City and found a 10% average decline during 24 months after the Fukushima disaster. A closer look at the numbers of observed and predicted LB in Table 1 [9] reveals that, in December 2011, 3649 missing births were found, a 10.2% drop, more than in the subsequent three months combined with 3630 missing births (-3.6%). After the Chernobyl accident on 26 April 1986, a drop in birth-rate was found in several European countries in the first quarter of 1987. The objective of the present study was to investigate whether a similar drop in live births occurred in Japan after the Fukushima nuclear accident.

Objectives

Results

Conclusion