Absence of Detectable Radionuclides in Breast Milk in Sendai, Japan in 2012 Even by High-Sensitivity Determination: Estimated Dose among Infants after the Fukushima Nuclear Disaster.

Zhaoqing Lyu,Manal A M Mahmoud,Tomoko Fujitani,Yukiko Fujii,Kouji H Harada,Sani Rachman Soleman

doi:10.3390/ijerph18115825

Abstract

The aim of this study was to estimate radionuclide levels in breast milk and the transferred dose to their infants in Sendai (100 km from Fukushima), Japan after the 2011 Fukushima nuclear disaster. Radionuclide concentrations were analyzed in 101 specimens of breast milk collected in 2012. Median values for minimum detectable activities were 0.39, 0.34, 1.1, 1.89, and 17.1 Bq/kg for 137Cs, 134Cs, 131I, 110mAg, and 40K, respectively. Only radionuclides from 40K were detected. To estimate potential exposure and radiocesium dose, we assumed that the samples contained each minimum detectable activity level. The mean minimum detectable activity concentrations (standard deviation) of 137Cs and 134Cs were 0.42 (0.15) and 0.37 (0.14) Bq/kg, respectively. Means of estimated dietary intakes of 137Cs and 134Cs among infants were 0.35 (0.12) and 0.31 (0.11) Bq/day, respectively. The committed effective doses of radiocesium in infants aged 3 and 12 months via breastmilk were estimated at 5.6 (2.1) and 3.3 (1.2) μSv/year, respectively. Dietary intakes of 137Cs and 134Cs in breastfeeding mothers were back-calculated at 1.9 (0.71) and 1.7 (0.65) Bq/day, respectively. The study verified no discernible exposure to radionuclides among infants. The most conservative estimates were below the Japanese internal exposure limit of 1 mSv/year.

Highlights

Introduction iationsFollowing a massive earthquake and tsunami on 11 March 2011 in northern Japan, the Fukushima Dai-ichi Nuclear Power Plant released radionuclides of rare gases, iodine, strontium, and cesium
Dietary intake of radiocesium was assessed in the adult population [3,4,5] and measured just under 10 Bq/day, as confirmed
Were medical practitioners (7.9% in 30–34 years at 2010 Japan census), perhaps indicating that their choice to participate in the study originated from a professional interest in radiation exposures

Summary

Introduction

Following a massive earthquake and tsunami on 11 March 2011 in northern Japan, the Fukushima Dai-ichi Nuclear Power Plant released radionuclides of rare gases, iodine, strontium, and cesium. The total amount of cesium-137 (137 Cs) discharged into the environment was around 1.3 × 1016 Bq in the early stage, and was roughly 10% that of the Chernobyl disaster in 1986 [1,2]. Several areas within 50 km of the plant were restricted for residence because of the high radiation exposure estimated. Radionuclides from radiocesium (137 Cs and 134 Cs) were dominant in the accident after the initial stage because of their longer half-lives Soils and food crops were contaminated by radiocesium, resulting in exposure of residents in Fukushima and the neighboring areas. Dietary intake of radiocesium was assessed in the adult population [3,4,5] and measured just under 10 Bq/day, as confirmed

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