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Kimura Y.,Nagasaki University | Okubo Y.,Nagasaki University | Hayashida N.,Nagasaki University | Takahashi J.,Nagasaki University | And 4 more authors.
PLoS ONE | Year: 2015

After the Chernobyl Nuclear Power Plant accident, the residents living around the Chernobyl were revealed to have been internally exposed to 137Cs through the intake of contaminated local foods. To evaluate the current situation of internal 137Cs exposure and the relationship between the 137Cs soil contamination and internal exposure in residents, we investigated the 137Cs body burden in residents who were living in 10 selected cities from the northern part of the Zhitomir region, Ukraine, and collected soil samples from three family farms and wild forests of each city to measured 137Cs concentrations. The total number of study participants was 36,862, of which 68.9%of them were female. After 2010, the annual effective doses were less than 0.1 mSv in over 90% of the residents. The 137Cs body burden was significantly higher in autumn than other seasons (p < 0.001) and in residents living in more contaminated areas (p < 0.001). We also found a significant correlation between the proportion of residents in each city with an estimated annual exposure dose exceeding 0.1 mSv and 137Cs concentration of soil samples from family farms (r = 0.828, p = 0.003). In conclusion, more than 25 years after the Chernobyl accident, the internal exposure doses to residents living in contaminated areas of northern Ukraine is limited but still related to 137Cs soil contamination. Furthermore, the consumption of local foods is considered to be the cause of internal exposure. © 2015 Kimura et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source


Taira Y.,Nagasaki University | Taira Y.,11 Health | Hayashida N.,Nagasaki University | Brahmanandhan G.M.,Nagasaki University | And 7 more authors.
Journal of Radiation Research | Year: 2011

To evaluate current environmental contamination and contributions from internal and external exposure due to the accident at the Chernobyl Nuclear Power Plant (CNPP) and nuclear tests at the Semipalatinsk Nuclear Testing Site (SNTS), concentrations of artificial radionuclides in edible mushrooms, soils and stones from each area were analyzed by gamma spectrometry. Annual effective doses were calculated for each area from the cesium contamination. Calculated internal effective doses of 137Cs due to ingestion of mushrooms were 1.8 × 10-1 mSv/year (y) in Gomel city (around CNPP), 1.7 × 10-1 mSv/y in Korosten city (around CNPP), 2.8 × 10-4 mSv/y in Semipalatinsk city, and 1.3 × 10-4 mSv/y in Nagasaki. Calculated external effective doses of 137Cs were 3.4 × 10-2 mSv/y in Gomel city, 6.2 × 10-2 mSv/y in Korosten city, 2.0 × 10-4 mSv/y in Semipalatinsk city, and 1.3 × 10-4 mSv/y in Nagasaki. Distribution of radionuclides in stones collected beside Lake Balapan (in SNTS) were 241Am (49.4 ± 1.4 Bq/kg), 137Cs (406.3 ± 1.7 Bq/kg), 58Co (3.2 ± 0.5 Bq/kg), and 60Co (125.9 ± 1.1 and 126.1 ± 1.1 Bq/kg). The present study revealed that dose rates from internal and external exposure around CNPP were not sufficiently low and radiation exposure potency still exists even though current levels are below the public dose limit of 1 mSv/y (ICRP1991). Moreover, parts of the SNTS area may be still contaminated by artificial radionuclides derived from nuclear tests. Long-term follow-up of environmental monitoring around CNPP and SNTS, as well as evaluation of health effects in the population residing around these areas, may contribute to radiation safety with a reduction of unnecessary exposure of residents. Source


Taira Y.,Nagasaki University | Taira Y.,11 Health | Hayashida N.,Nagasaki University | Yamashita S.,Nagasaki University | And 6 more authors.
Radiation Protection Dosimetry | Year: 2012

To evaluate the environmental contamination and contributory external exposure after the accident at the Fukushima Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples from each area were analysed by gamma spectrometry. Six artificial radionuclides (131I, 134Cs, 137Cs, 129mTe, 95Nb and 136Cs) were detected in soil samples around FNPP. Calculated external effective doses from artificial radionuclide contamination in soil samples around FNPP were 1.9-2.9 μSv h-1 (8.7-17.8 mSv y. -1) in Fukushima city on 22 March 2011. After several months, these calculated external effective doses were 0.25-0.88 μSv h-1 (2.2-7.6 mSv y. -1) in Fukushima city on 29 June 2011. The present study revealed that the detected artificial radionuclides around FNPP mainly shifted to long-lived radionuclides such as radioactive caesium (134Cs and 137Cs) even though current levels are decreasing gradually due to the decay of short-lived radionuclides such as 131I, 129mTe, 95Nb and 136Cs. Thus, radiation exposure potency still exists even though the national efforts are ongoing for reducing the annual exposure dose closer to 1 mSv, the public dose limit. Long-term environmental monitoring around FNPP contributes to radiation safety, with a reduction in unnecessary exposure to the residents. © The Author 2012. Published by Oxford University Press. All rights reserved. Source


Sekitani Y.,Nagasaki University | Hayashida N.,Nagasaki University | Takahashi J.,Nagasaki University | Kozlovsky A.A.,Gomel State Medical University | And 6 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2013

Background: Iodine requirements increase during pregnancy and previous studies have reported the inadequate iodine status of pregnant women in areas that have achieved iodine sufficiency in the general population. We examined the urinary iodine (UI) concentrations of pregnant women in Ukraine, where the iodine status is showing improvement among the general population. Methods: We enrolled 148 pregnant women<16 weeks pregnant and 80 healthy women as a control group living in Zhitomir, Ukraine. UI concentration, thyroid-stimulating hormone (TSH), antithyroglobulin antibodies (TGAb), and antithyroid peroxidase antibodies (TPOAb) were measured. Results: The median UI concentrations were significantly lower in pregnant women than in control women [13.0 (ND - 51.0) μg/L vs. 62.0 (35.3 - 108.5) μg/L, p<0.001]. TSH concentrations were significantly lower in pregnant women than in control women [1.7 (1.2 - 2.7) IU/L vs. 2.2 (1.4 - 3.1) IU/L, p = 0.011], but this difference disappeared when adjusted for age (2.1 ± 0.1 IU/L vs. 2.4 ± 0.2 IU/L, p = 0.097). The frequency of TSH over 6.2 IU/L and the frequency of positive TGAb and/or TPOAb were not statistically different between groups (p = 0.70 and p = 0.48, respectively). The UI concentrations of 142 pregnant women (95.9 % ) were<150 μg/L indicating insufficient iodine intake. Conclusions: The UI concentration of pregnant women in Ukraine revealed severe iodine deficiency. Regular monitoring and appropriate nutrition education are essential because iodine deficiency can be easily prevented by adequate iodine intake. The risk of iodine deprivation during pregnancy needs to be assessed locally over time because it may occur in areas that are not globally recognized as being iodine-deficient. Source


Hayashida N.,Nagasaki University | Sekitani Y.,Nagasaki University | Takahashi J.,Nagasaki University | Kozlovsky A.A.,Gomel State Medical University | And 10 more authors.
PLoS ONE | Year: 2012

Objective: After the accident at the Chernobyl Nuclear Power Plant (CNPP), the incidence of thyroid cancer increased among children. Recently, a strong relationship between solid thyroid nodules and the incidence of thyroid cancer was shown in atomic bomb survivors. To assess the prognosis of benign thyroid nodules in individuals living in the Zhitomir region of Ukraine, around the CNPP, we conducted a follow-up investigation of screening data from 1991 to 2000 in the Ukraine. Patients and Methods: Participants of this study were 160 inhabitants with thyroid nodules (nodule group) and 160 inhabitants without thyroid nodules (normal control group) intially identified by ultrasonography from 1991 to 2000. All participants were aged 0 to 10 years old and lived in the same area at the time of the accident. We performed follow-up screening of participants and assessed thyroid nodules by fine needle aspiration biopsy. Results: Among the nodule group participants, the number and size of nodules were significantly increased at the follow-up screening compared with the initial screening. No thyroid nodules were observed among the normal control group participants. The prevalence of thyroid abnormality, especially nodules that could be cancerous (malignant or suspicious by fine needle aspiration biopsy), was 7.5% in the nodule group and 0% in the normal control group (P<0.001). Conclusions: Our study indicated that a thyroid nodule in childhood is a prognostic factor associated with an increase in the number and size of nodules in individuals living in the Zhitomir region of Ukraine. © 2012 Hayashida et al. Source

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