December 17, 2018
Despite a high distribution rate of stable iodine after the 2011 Fukushima nuclear accident in Japan, only 63.5% of parents reported children took the tablets, with many citing safety concerns in questionnaires, according to findings published in The Journal of Clinical Endocrinology & Metabolism.
The intake of stable iodine after a nuclear emergency is a key strategy for preventing childhood thyroid cancer, along with evacuation and other measures, Yoshitaka Nishikawa, MD, a physician and medical researcher in the department of internal medicine at Hirata Central Hospital in Fukushima, Japan, and colleagues wrote in the study background. The timing of iodine administration is optimally between 24 hours before and up to 2 hours after the expected onset of exposure, they noted; however, iodine is still reasonably effective when taken up to 8 hours later. To date, there is limited information about the acceptability and feasibility of implementation of iodine distribution in actual cases, they wrote.
“To prepare for future nuclear emergencies, investigations of the operational issues in an actual case are needed,” the researchers wrote.
In a retrospective, observational study, Nishikawa and colleagues analyzed data from 961 children from Miharu, a town in Fukushima prefecture, who underwent biennial thyroid screenings at Hirata Central Hospital between August and November 2017 (median age at time of accident, 5 years). In addition to the Fukushima Health Management Survey, Miharu has continued thyroid screenings for all primary and secondary school students.
In Miharu, health care professionals distributed stable iodine to 3,134 households (94.9% distribution rate) after explosions at the Fukushima nuclear plant caused by the 2011 earthquake in eastern Japan, along with instructions provided by the local government. Screening and questionnaire records included age of participants at the time of the nuclear accident, sex, region of residence before the accident, whether the participant was evacuated, whether the child and parents took stable iodine orally after the accident and dietary habits, including iodine intake. Researchers used logistic regression models to identify factors associated with stable iodine intake.
Within the cohort, 610 children (63.5%) had taken stable iodine, according to questionnaire data.
Researchers found that children were more likely to take stable iodine provided after the accident if their parents took stable iodine (OR = 61; 95% CI, 37.9-102.9). Compared with preschool and school-aged children, infants (aged 2 years or younger) were less likely to take stable iodine (OR = 0.21; 95% CI, 0.11-0.36).
In assessing questionnaire data from parents who reported children did not take stable iodine (n = 351), concern about safety was the most frequent reason provided (n = 164; 46.2%), followed by evacuation to other areas, no national or prefectural instruction and iodine not being delivered.
“Qualitative analysis revealed that concern about safety was the major reason for avoiding intake,” the researchers wrote. “Other issues related to distribution methods, information about the effects and adverse events and instruction about intake. In future nuclear disasters, it would be important to explain to both children and parents the effects and adverse effects of iodine intake and to provide detailed instructions about the intake of iodine by infants.” – by Regina Schaffer