No significant association between stable iodine intake and thyroid dysfunction in children after the Fukushima Nuclear Disaster: an observational study

Abstract Purpose Stable iodine prophylaxis helps prevent childhood thyroid cancer in nuclear emergencies; however, there is limited information on its effect on thyroid function. This study aimed to examine thyroid function and autoimmunity among children and adolescents that took stable iodine after the Fukushima Nuclear Disaster. Methods For this observational study, data were obtained from children and adolescents that underwent thyroid cancer screening at Hirata Central Hospital from April 2012 to March 2018. Participant characteristics, including possible hypothyroidism and hyperthyroidism, were compared between the prophylaxis and no-prophylaxis groups. Multivariable logistic regression models were used to assess for possible hypothyroidism, autoantibodies positive, and hyperthyroidism. Results A total of 1,225 participants with stable iodine prophylaxis and 3,946 without prophylaxis were enrolled. Of those participants, blood samples were available for 144 and 1,201 participants in the prophylaxis and no-prophylaxis groups, respectively. There were 17 (11.8%) and 146 cases (12.2%) of possible hypothyroidism or autoantibodies positive cases in the prophylaxis and no-prophylaxis groups, respectively, and there were no cases and 3 cases (0.2%) of possible hyperthyroidism in those two groups, respectively. Multivariable analysis for possible hypothyroidism revealed no association between stable iodine intake and possible hypothyroidism or autoantibodies positive [odds ratio 0.716 (95% confidence interval 0.399–1.284)] (p = 0.262). We did not perform multivariable analysis for hyperthyroidism due to the limited number of cases. Conclusion Significant adverse effects of stable iodine intake on thyroid function were not observed among children and adolescents 7 years after the Fukushima Nuclear Disaster.

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Stable Iodine Distribution Among Children After the 2011 Fukushima Nuclear Disaster in Japan: An Observational Study

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2018-02136 ◽

2018 ◽

Vol 104 (5) ◽

pp. 1658-1666 ◽

Cited By ~ 2

Author(s):

Yoshitaka Nishikawa ◽

Ayako Kohno ◽

Yoshimitsu Takahashi ◽

Chiaki Suzuki ◽

Hirokatsu Kinoshita ◽

...

Keyword(s):

Thyroid Cancer ◽

Adverse Effects ◽

Observational Study ◽

Iodine Intake ◽

Intake Rate ◽

Distribution Method ◽

Fukushima Nuclear Disaster ◽

Childhood Thyroid Cancer ◽

Fukushima Disaster ◽

Stable Iodine

Abstract Context Intake of stable iodine helps prevent childhood thyroid cancer in nuclear emergencies, but there is limited case information. Objective We identified the intake rate and the factors associated with no intake among children who did not take stable iodine after the Fukushima disaster. Design Retrospective observational study. Setting Data were obtained from thyroid cancer screenings performed from August through November 2017. Participants Children in Miharu Town, Fukushima, Japan. Intervention No intervention. Main Outcome Measures We performed multilevel logistic regression analysis at the regional and individual levels. We qualitatively examined the reasons for no intake of stable iodine based on closed- and open-ended questions. Results The rate of distribution was 94.9%, but the intake rate was only 63.5%. Intake was lower in those aged 0 to 2 years compared with those aged ≥3 years (OR, 0.21; 95% CI, 0.11 to 0.36). Parents’ intake was positively associated with their children’s intake (OR, 61.0; 95% CI, 37.9 to 102.9). The variance partition coefficient for regions was 0.021, suggesting that the intake of stable iodine was more likely affected by individual than by regional factors. Closed-ended questions showed that the main reason for avoiding intake was concern about safety. Open-ended questions for other reasons revealed issues related to the distribution method, information about the effects and adverse effects of iodine, and instructions for iodine intake. There were no symptomatic adverse effects claimed to the town. Conclusions The distribution and consumption of stable iodine occurred in Miharu Town after the Fukushima disaster. To prepare for future nuclear emergencies, it is important to explain to both children and parents the need for intake of stable iodine, particularly among young children.

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Non-communicable diseases in decontamination workers in areas affected by the Fukushima nuclear disaster: a retrospective observational study

BMJ Open ◽

10.1136/bmjopen-2016-013885 ◽

2016 ◽

Vol 6 (12) ◽

pp. e013885 ◽

Cited By ~ 9

Author(s):

Toyoaki Sawano ◽

Masaharu Tsubokura ◽

Akihiko Ozaki ◽

Claire Leppold ◽

Shuhei Nomura ◽

...

Keyword(s):

Observational Study ◽

Communicable Diseases ◽

Retrospective Observational Study ◽

Non Communicable Diseases ◽

Nuclear Disaster ◽

Fukushima Nuclear Disaster

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Relevance of iodine intake as a reputed predisposing factor for thyroid cancer

Arquivos Brasileiros de Endocrinologia & Metabologia ◽

10.1590/s0004-27302007000500007 ◽

2007 ◽

Vol 51 (5) ◽

pp. 701-712 ◽

Cited By ~ 47

Author(s):

Meyer Knobel ◽

Geraldo Medeiros-Neto

Keyword(s):

Thyroid Cancer ◽

Iodine Deficiency ◽

Animal Experiments ◽

Experimental Studies ◽

Epidemiological Studies ◽

Iodine Intake ◽

Thyroid Cell ◽

Predisposing Factor ◽

Iodine Prophylaxis ◽

Iodine Excess

Iodine is a trace element that is essential for the synthesis of thyroid hormone. Both chronic iodine deficiency and iodine excess have been associated with hypertrophy and hyperplasia of follicular cells, attributed to excessive secretion of TSH. This may be associated to thyroid cancer risk, particularly in women. Experimental studies have documented thyroid cancer induction by elevation of endogenous TSH, although in a small number of animals. Iodine deficiency associated with carcinogenic agents and chemical mutagens will result in a higher incidence of thyroid malignancy. Inadequate low iodine intake will result in increased TSH stimulation, increased thyroid cell responsiveness to TSH, increased thyroid cell EGF-induced proliferation, decreased TGFbeta 1 production and increased angiogenesis, all phenomena related to promotion of tumor growth. Epidemiological studies associating iodine intake and thyroid cancer led to controversial and conflicting results. There is no doubt that introduction of universal iodine prophylaxis in population previously in chronic iodine-deficiency leads to a changing pattern of more prevalent papillary thyroid cancer and declining of follicular thyroid cancer. Also anaplastic thyroid cancer is practically not seen after years of iodine supplementation. Iodine excess has also been indicated as a possible nutritional factor in the prevalence of differentiated thyroid cancer in Iceland, Hawaii and, more recently, in China. In conclusion: available evidence from animal experiments, epidemiological studies and iodine prophylaxis has demonstrated a shift towards a rise in papillary carcinoma, but no clear relationship between overall thyroid cancer incidence and iodine intake.

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Prevalence of non-communicable diseases among healthy male decontamination workers after the Fukushima nuclear disaster in Japan: an observational study

Scientific Reports ◽

10.1038/s41598-021-01244-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Toyoaki Sawano ◽

Michio Murakami ◽

Akihiko Ozaki ◽

Yoshitaka Nishikawa ◽

Aoi Fukuda ◽

...

Keyword(s):

Health Status ◽

Observational Study ◽

Communicable Diseases ◽

Health Promotion Program ◽

Healthy Male ◽

Non Communicable Diseases ◽

Nuclear Disaster ◽

Health And Nutrition ◽

Prevalence Of Obesity ◽

Fukushima Nuclear Disaster

AbstractThe health status of healthy decontamination workers employed after the Fukushima nuclear disaster remains unclear. This study aimed to evaluate the prevalence of non-communicable diseases among such workers. In this observational study, questionnaires on lifestyle and social factors were administered as part of a health promotion program for decontamination workers in 2016 in Minamisoma City, Fukushima. The questionnaires and health check-up results were compared with those of the 2016 National Health and Nutrition Examination Survey (NHANES) in Japan. Overall, 123 male decontamination workers were enrolled; 93 (75.6%) were drinkers, and 84 (68.3%) were current smokers. The age-adjusted prevalence (95% confidence interval) of hypertension, dyslipidemia, diabetes mellitus, and obesity were 27.2% (20.1–34.4%), 30.4% (22.6–38.2%), 11.3% (5.5–17.1%), and 49.0% (39.0–58.9%), respectively. The age-adjusted prevalence in the NHANES were 32.8% (31.1–34.5%), 16.1% (14.5–17.6%), 7.0% (6.2–7.7%), and 31.2% (29.9–32.5%), respectively. The prevalence of obesity, dyslipidemia, binge drinking, and smoking were higher in healthy male decontamination workers than in the general population. Decontamination workers in disaster-struck areas may have higher risks of developing non-communicable diseases, possibly due to their original health status. Continuous monitoring of their health status and proper interventions are warranted.

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