Implementation of iodine biokinetic model for interpreting I-131 contamination in breast milk after the Fukushima nuclear disaster

• Published in: Scientific reports Vol. 5; no. 1; p. 12426
• Main Authors: Tani, Kotaro, Kurihara, Osamu, Kim, Eunjoo, Yoshida, Satoshi, Sakai, Kazuo, Akashi, Makoto
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.07.2015; Nature Publishing Group
• Subjects: 631/443/319; 639/705/1042; 692/499; 692/700/478; Baby foods; Breast Feeding - methods; Breast milk; Breastfeeding & lactation; Female; Food contamination; Fukushima Nuclear Accident; Humanities and Social Sciences; Humans; Infant; Infants; Inhalation; Iodine; Iodine - metabolism; Iodine Isotopes - metabolism; Lactation; Milk; Milk, Human - metabolism; Models, Theoretical; multidisciplinary; Nuclear Power Plants; Nursing; Radiation Dosage; Radiation Monitoring - methods; Science; Thyroid; Thyroid Gland - radiation effects
• DOI: 10.1038/srep12426
• ISSN: 2045-2322

After the accident at the Fukushima Daiichi Nuclear Power Plant run by Tokyo Electric Power Company in 2011, breast milk samples obtained from volunteers living in Fukushima and neighboring prefectures were examined and small amounts of I-131 (2.2–36.3 Bq/kg) were detected in some samples. In this work, the I-131 concentrations in breast milk from nursing mothers in Ibaraki prefecture were calculated based on the iodine biokinetic model during lactation together with time-variable intake scenarios by inhalation of ambient air and ingestion of tap water, using the authors’ code. The calculated I-131 concentrations in breast milk generally agreed with those measured for the volunteers. Based on the results, thyroid equivalent doses to breast-fed infants were estimated for each place of residence of the volunteers on the assumption that these infants consumed 800 ml of breast milk every day, resulting in 10–11 mSv for Mito and Kasama cities and 1.1–1.8 mSv for Tsukuba and Moriya cities. It was suggested that breast milk consumption could be a major contributor to internal dose of breast-fed infants in areas with mild I-131 pollution; however, further studies considering personal behavior surveys would be necessary to estimate individual doses.