Thyroid doses for evacuees from the Fukushima nuclear accident

Abstract

A primary health concern among residents and evacuees in affected areas immediately after a nuclear accident is the internal exposure of the thyroid to radioiodine, particularly I-131, and subsequent thyroid cancer risk. In Japan, the natural disasters of the earthquake and tsunami in March 2011 destroyed an important function of the Fukushima Daiichi Nuclear Power Plant (F1-NPP) and a large amount of radioactive material was released to the environment. Here we report for the first time extensive measurements of the exposure to I-131 revealing I-131 activity in the thyroid of 46 out of the 62 residents and evacuees measured. The median thyroid equivalent dose was estimated to be 4.2 mSv and 3.5 mSv for children and adults, respectively, much smaller than the mean thyroid dose in the Chernobyl accident (490 mSv in evacuees). Maximum thyroid doses for children and adults were 23 mSv and 33 mSv, respectively.

Measurements of Individual Radiation Doses in Residents Living Around the Fukushima Nuclear Power Plant

“…They found detectable 131 I activity in 39 of the 45 people evacuated from coastal areas, and in 7 of the 17 residents in Tsushima District (Namie Town). Thyroid equivalent doses by inhalation ranged from none detected to 33 mSv (19). The median thyroid equivalent doses for children and adults were 4.2 and 3.5 mSv, respectively.…”

Outline of the Radiation Dose Estimation of Residents After the Fukushima Daiichi Nuclear Power Plant Accident

“…The Japanese government carried out a screening survey for 1,062 children living near the nuclear plant and reported that no child had an equivalent thyroid dose of more than 50 mSv. Tokonami et al also measured radioiodine activity in thyroid in situ [ 6 ]. Radioiodine activity determined by a whole-body counter in the volunteer workers at the shelter facilities is presented by Kinashi et al in Chap.…”

Understanding the Health Impacts and Risks of Exposure to Radiation

“…It is estimated that 160, 88, 18, and 15 PBq of 131 I, 132 Te, 134 Cs, and 137 Cs, respectively, were discharged from the Fukushima Daiichi NPP into the environment [43]. A primary health concern for internal exposure to 131 I is the potential development of thyroid cancer, since the thyroid gland is most sensitive to 131 I [44]. Examples of deterministic health effects induced by inhalation of β-emitting 131 I include bone marrow depression (1-10 Gy), hypothyroidism (10-100 Gy), and ablation of the thyroid gland (100-100 Gy).…”

“…Once 131 I is taken up by the thyroid gland, a constant bombardment of surrounding tissue can overwhelm the repair mechanisms of cells and trigger cancer [3]. Tokonamii et al calculated the median thyroid equivalent dose to 4.2 and 3.5 mSv for children and adults, respectively [44].…”