Radiation Health Effects

Thus far, no significant effects of radiation from the nuclear accident have been confirmed in either the Thyroid Ultrasound Examination program or the Pregnancy and Birth Survey.

Thyroid Ultrasound Examination (TUE)

Evaluation of Findings from the Preliminary Baseline Survey through the Full-Scale Survey (Fifth Round)

"No association between thyroid cancer and radiation exposure was identified in the Preliminary Baseline Survey through the fifth-round Full-Scale Survey."
"Given that more multifaceted and multilayered analyses became possible compared with what was done through the fourth-round Survey, the conclusions can now be stated with even greater confidence."

Main reasons for this evaluation

Source: Document 5-2 from the 56th Meeting of the Fukushima Prefectural Oversight Committee for the Fukushima Health Management Survey, July 2025.

The results of the Pregnancy and Birth Survey (PBS)

Preterm births, low birth weights, and congenital anomalies have been consistent with national government statistics and commonly reported data in general.

Source: The 44th Fukushima Prefectural Oversight Committee, May, 2022 / Guidelines for Obstetrics practice 2023

Preterm births rate, Low birth weight rate, and Congenital anomalies Rate

Preterm births rate Low birth weight rate Congenital anomalies Rate
FY2011 4.6 (5.7) 8.6 (9.6) 2.85 (2 - 3)*
FY2012 5.6 (5.7) 9.2 (9.6) 2.39
FY2013 5.2 (5.8) 9.6 (9.6) 2.35
FY2014 5.3 (5.7) 9.8 (9.5) 2.30
FY2015 5.6 (5.6) 9.4 (9.5) 2.24
FY2016 5.3 (5.6) 9.2 (9.4) 2.55
FY2017 5.3 (5.7) 9.2 (9.4) 2.38
FY2018 5.2 (5.6) 9.0 (9.4) 2.19
FY2019 5.1 (5.6) 9.1 (9.4) 2.71
FY2020 4.4 (5.5) 8.1 (9.2) 2.21

Figures in the brackets are the proportion of preterm deliveries and incidence of low birth weight infants reported in Vital Statistics published by the Ministry of Health, Labour and Welfare for the same fiscal year.
* Figures in the brackets are generally reported incidence in the Guideline for Obstetrical Practice (2023)