Administration Of Stable Iodine Research Articles

Determinants of target absorbed dose in radionuclide therapy

In radionuclide therapy, activity kinetics in tissues determine the absorbed doses administered and thus efficacy and side effects of treatment. The objective of this work was to derive expressions for the parameters affecting the absorbed dose to a target tissue for first-order activity kinetics.The activity uptake results from contributions from the first-pass activity flow through the target tissue preceding systemic equilibration and uptake after distribution of the administered compound in the body. The absorbed dose from uptake after equilibration is the product of the mean energy deposited per decay in the target tissue, the time integral of the plasma activity concentration, the plasma volume flow per unit target tissue mass, the probability of activity removal during passage, and the mean lifetime of activity in the target tissue.Quantitative analysis of the determinants of absorbed dose exemplarily for radioiodine therapy indicates that the high uptake often observed in Graves’ disease must be associated with high tissue perfusion and removal probability and that administration of stable iodine increases mean lifetime. For therapies with long residence times of the active compound in the blood, such as radioiodine therapy, the contribution of the first-pass is small compared with uptake after equilibration. The relative first-pass contribution is higher for agents that are rapidly eliminated from the blood pool, such as radiolabelled somatostatin analogues, and may dominate after arterial application.Understanding the determining parameters in radionuclide therapy reveals dose-limiting factors and opens up opportunities to optimise and individualize therapy, potentially improving treatment success rates.

Effects of repetitive Iodine thyroid blocking on the foetal brain and thyroid in rats: a systems biology approach

A single administration of an iodine thyroid blocking agent is usually sufficient to protect thyroid from radioactive iodine and prevent thyroid cancer. Repeated administration of stable iodine (rKI) may be necessary during prolonged or repeated exposure to radioactive iodine. We previously showed that rKI for eight days offers protection without toxic effects in adult rats. However, the effect of rKI administration in the developing foetus is unknown, especially on brain development, although a correlation between impaired maternal thyroid status and a decrease in intelligence quotient of the progeny has been observed. This study revealed distinct gene expression profiles between the progeny of rats receiving either rKI or saline during pregnancy. To understand the implication of these differentially expressed (DE) genes, a systems biology approach was used to construct networks for each organ using three different techniques: Bayesian statistics, sPLS-DA and manual construction of a Process Descriptive (PD) network. The PD network showed DE genes from both organs participating in the same cellular processes that affect mitophagy and neuronal outgrowth. This work may help to evaluate the doctrine for using rKI in case of repetitive or prolonged exposure to radioactive particles upon nuclear accidents.

Social uncertainties related to stable iodine intake in a nuclear emergency

Intake of stable iodine intake is considered as an effective countermeasure for reducing the risk of thyroid cancer in an eventual release of radioactive iodine following nuclear accident. However, there are a number of value and social uncertainties that are likely to impact on accident management. These include differences in public response as well as decisions made by emergency management actors during an actual incident. In order to explore these sources of uncertainty, this paper explored social uncertainties related to the potential administration of stable iodine. First, public understanding and compliance with the advice of authorities was studied by surveys, showing that less than half of the public knew when iodine tablets should be taken, or understood their protective role. There were also country specific differences in the level of expected compliance with authorities’ advice. Second, social uncertainties were identified through observations of emergency exercises; these were revealed to be mainly related to timing, public response, communication, effectiveness, cross-border issues and first responders. Third, studies on factors influencing communication about stable iodine were carried out and showed that public understanding and compliance with advice could be improved by communicating numerical and narrative information. Overall, the results indicate that enhanced focus on social uncertainties during the preparedness phase may improve the effectiveness of stable iodine administration in case of an emergency.

Application of the new ICRP iodine biokinetic model for internal dosimetry in case of thyroid blocking

Administration of stable iodine has been considered a best measure to protect the thyroid from internal irradiation by radioiodine intake, and its efficacy on thyroid protection has been quantitatively evaluated in several simulation studies on the basis of simple iodine biokinetic models (i.e., three-compartment model). However, the new iodine biokinetic model adopted by the International Commission on Radiological Protection interprets and expresses the thyroid blocking phenomenon differently. Therefore, in this study, the new model was analyzed in terms of thyroid blocking and implemented to reassess the protective effects and to produce dosimetric data. The biokinetic model calculation was performed using computation modules developed by authors, and the results were compared with those of experimental data and prior simulation studies. The new model predicted protective effects that were generally consistent with those of experimental data, except for those in the range of stable iodine administration −72 h before radioiodine exposure. Additionally, the dosimetric data calculated in this study demonstrates a critical limitation of the three-compartment model in predicting bioassay functions, and indicated that dose assessment 1 d after exposure would result in a similar dose estimate irrespective of the administration time of stable iodine.

Japanese food data challenge the claimed link between Fukushima’s releases and recently observed thyroid cancer increase in Japan

Internal, high-dose exposure with radioiodine is known to increase the risk for thyroid cancer in children and adolescents. Ingestion of contaminated food is generally regarded a dominant route of internal exposure. We analyzed the huge data set of the post-Fukushima food monitoring campaign and deployed a conservative model for the estimation of the doses to the general public in a worst-case scenario. Our data suggest that the committed equivalent ingestion doses to the thyroids of the affected Japanese public, even in the utmost conservative approach, remained below the limit on ingestion of radioiodine in foodstuffs and beverages of 50 mSv (as thyroid equivalent dose). This level of 50 mSv is also the intervention level for the administration of stable iodine, mainly after inhalation. Our study hence suggests that, based on the food data, the internal exposure of Japanese residents was too low to cause a statistically discernible increase in thyroid cancer, even if the contribution from inhalation is taken into account. The data also indicate that the governmental efforts in the food monitoring campaign were successful and cut the thyroid doses to the public by a factor of approximately 3 compared to a scenario without any monitoring.

Japanese Food Data Challenge the Claimed Link between Fukushima\u2019s Releases and Recently Observed Thyroid Cancer Increase in Japan

Internal, high-dose exposure with radioiodine is known to increase the risk for thyroid cancer in children and adolescents. Ingestion of contaminated food is generally regarded a dominant route of internal exposure. We analyzed the huge data set of the post-Fukushima food monitoring campaign and deployed a conservative model for the estimation of the doses to the general public in a worst-case scenario. Our data suggest that the committed equivalent ingestion doses to the thyroids of the affected Japanese public, even in the utmost conservative approach, remained below the limit on ingestion of radioiodine in foodstuffs and beverages of 50 mSv (as thyroid equivalent dose). This level of 50 mSv is also the intervention level for the administration of stable iodine, mainly after inhalation. Our study hence suggests that, based on the food data, the internal exposure of Japanese residents was too low to cause a statistically discernible increase in thyroid cancer, even if the contribution from inhalation is taken into account. The data also indicate that the governmental efforts in the food monitoring campaign were successful and cut the thyroid doses to the public by a factor of approximately 3 compared to a scenario without any monitoring.

Radiation protection and long-term health management of workers after the Fukushima Daiichi nuclear power plant accident.

Introduction: The Fukushima Daiichi Nuclear Power Plant (NPP) 1 was severely damaged from the chain reaction of the Great East Japan Earthquake and Tsunami on 11 March 2011. This resulted in the worst nuclear accident since Chernobyl accident of 1986. Just like the case of Chernobyl, emergency workers were recruited to conduct wide ranges of tasks like disaster response, rescuing activities, NPP containment, and radiation decontamination. Methods: This paper describes the types and efficacy of the various occupational health interventions introduced to the Fukushima NPP radiation workers by the literature reviews. Results: Less than 1% of all emergency workers were exposed to external radiation >100mSv, and to-date, no deaths or health adversities from radiation have been reported from those workers. Several occupational health interventions were conducted, including setting new regulatory exposure limits, improving workers’ radiation dosimetry, administration of stable iodine, running an occupational health tracking system, and improving occupational medicine and preventative care. Those interventions were not only vital for preventing unnecessary radiation, but also for managing other general health issues such as mental health, heat illness and infectious diseases. On 20 Oct 2015, the Ministry of Health, Labour and Welfare, Japan (MHLW) announced that one worker who had been working at the NPP diagnosed with leukemia. The MHLW admitted that it is difficult to say that the cancer was not related to the work, and decided to accept the compensation claim the worker had filed. After the accident, we have been developing multi-disciplinary biodosimetric systems including the L-band and X-band EPR dosimetery systems, y-H2AX assay, mutation assay, and so on. Conclusions: The long-term administration of the occupational health interventions are essential to ensure ongoing support and care for the workers that were put under one of the most severe health risks.

Thyroid side effects prophylaxis in front of nuclear power plant accidents

The better knowledge of the mechanisms of nuclear incidents and lessons learned from accidents in the recent past to improve the effectiveness of measures taken following a nuclear accident exposure to fallout of radioactive iodine isotopes. Thus, immediate, passive measures, such as containment, and stopping consumption of contaminated products are paramount. The earliest possible administration of stable iodine as potassium iodide (KI) reduces significantly (up to 90% if taken at the same time of the accident) thyroid radioactive contamination. These tablets should be given in priority to children and pregnant women. The side effects are minor. KI is not recommended for persons aged over 60years, or for adults suffering from cardiovascular disorders.

Reliability of Questionnaire Data in the Distant Past: Relevance for Radiation Exposure Assessment.

Interviews with questionnaires are often employed to provide information that may be used for exposure assessment, although the reliability of such information is largely unknown. In this work, the consistency of individual behavior and dietary data collected by means of personal interviews during two study screenings was evaluated. Data were collected for a cohort of about 11,000 persons exposed to 131I in childhood and adolescence shortly after the Chernobyl accident. The best recollection was found for residential history, milk consumption patterns, and, to a lesser degree, stable iodine administration, while reproducibility of responses about consumption of milk products and leafy vegetables was poor. Consistency of information reported during the personal interviews by the study subjects younger than 10 y at the time of the accident was somewhat lower than for the subjects aged 10-18 y. The authors found slightly better reproducibility of responses for female study subjects than for male subjects and when the time span between two interviews was shorter. In the majority of instances, the best consistency in responses was observed when the mother was interviewed during both screenings rather than the subject. Information that was collected during two personal interviews was used to calculate two sets of thyroid doses due to 131I intakes. This study shows that, because dose-related measurements are available for all study subjects, the quality of individual behavior and dietary data has, in general, a small influence on the results of the retrospective dose assessment. For studies in which dose-related measurements are not available for all study subjects and only modeling is used for dose reconstruction, high quality individual behavior and dietary data for the study subjects are required to provide realistic and reliable dose estimates.

A Study of Thyroid 131I Activity of Five Human Subjects Exposed to a Radioactive Plume at Tamura City in Fukushima.

Thyroid 131I activities were determined for five human subjects from a disaster medical assistance team of Fukui Prefectural Hospital. The team was dispatched to the Tamura City Sports Park, 40 km from the Fukushima Daiichi nuclear power plant. They were exposed to a radioactive plume on 15 March 2011. In vivo measurements at Fukui Prefectural Hospital were conducted around 17 h after the team left the park. A thyroid counter equipped with a 51-mm-diameter × 51-mm-thick NaI(Tl) detector with a 20-mm-thick lead collimator was used. Mock iodine (133Ba and 137Cs) with a thyroid uptake neck phantom was used for calibration. On 16 March 2011, at 11:30, thyroid activity of a member of the team age 53 y, who was never administered stable iodine, was 268 ± 38 Bq. The remaining four men, aged 49, 35, 34, and 27 y, ingested two stable iodine pills (a total of 100 mg of potassium iodide) approximately 36 h before being exposed to the plume. Their thyroid activity values were 249 ± 86 Bq, 676 ± 107 Bq, 569 ± 96 Bq, and 1,082 ± 119 Bq, respectively. An inverse relationship between age and thyroid activity was observed among those who ingested potassium iodide before exposure, indicating that stable iodine administration may have a protective effect. Thyroid 131I activity was reduced by approximately 70% in the oldest person. This can be explained by the iodine metabolism in the thyroid of younger individuals being significantly faster than that of older individuals.

Radiation occupational health interventions offered to radiation workers in response to the complex catastrophic disaster at the Fukushima Daiichi Nuclear Power Plant.

The Fukushima Daiichi Nuclear Power Plant (NPP) 1 was severely damaged from the chain reaction of the Great East Japan Earthquake and Tsunami on 11 March 2011, and the consequent meltdown and hydrogen gas explosions. This resulted in the worst nuclear accident since the Chernobyl accident of 1986. Just as in the case of Chernobyl, emergency workers were recruited to conduct a wide range of tasks, including disaster response, rescuing activities, NPP containment, and radiation decontamination. This paper describes the types and efficacy of the various occupational health interventions introduced to the Fukushima NPP radiation workers. Such interventions were implemented in order to prevent unnecessary radiation overexposure and associated adverse health effects and work injuries. Less than 1% of all emergency workers were exposed to external radiation of >100 mSv, and to date no deaths or health adversities from radiation have been reported for those workers. Several occupational health interventions were conducted, including setting of new regulatory exposure limits, improving workers' radiation dosimetry, administration of stable iodine, running an occupational health tracking system, and improving occupational medicine and preventative care. Those interventions were not only vital for preventing unnecessary radiation, but also for managing other general health issues such as mental health, heat illness and infectious diseases. Long-term administration of the aforementioned occupational health interventions is essential to ensure the ongoing support and care for these workers, who were put under one of the most severe occupational health risk conditions ever encountered.

A review of the Fukushima nuclear reactor accident: radiation effects on the thyroid and strategies for prevention.

This is a summary of the nuclear accident at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Stations (FDNPS) on 11 March 2011 to be used as a review of the radiation effects to the thyroid and strategies of prevention. The amount of radioiodine released to the environment following the Fukushima accident was 120 Peta Becquerel, which is approximately one-tenth of that in the Chernobyl accident. Residents near the FDNPS were evacuated within a few days and foodstuffs were controlled within 1 or 2 weeks. Therefore, thyroid radiation doses were less than 100 mSv (intervention levels for stable iodine administration) in the majority of children, including less than 1 year olds, living in the evacuation areas. Because the incidence of childhood thyroid cancer increased in those residing near the site following the Chernobyl accident, thyroid screening of all children (0-18 years old) in the Fukushima Prefecture was started. To date, screening of more than 280 000 children has resulted in the diagnosis of thyroid cancer in 90 children (approximate incidence, 313 per million). Thus, although the dose of radiation was much lower, the incidence of thyroid cancer appears to be much higher than that following the Chernobyl accident. A comparison of the thyroidal consequences following the Fukushima and Chernobyl nuclear reactor accidents is discussed. We also summarize the recent increased incidence in thyroid cancer in the Fukushima area following the accident in relation to increased thyroid ultrasound screening and the use of advanced ultrasound techniques. http://links.lww.com/COE/A8.

Initial activities of a radiation emergency medical assistance team to Fukushima from Nagasaki

As an urgent response to serious radiological accidents in the Fukushima Daiichi nuclear power plant, the radiation emergency medical assistance team (REMAT) from Nagasaki University landed at Fukushima on March 14, 2011, two days after the initiation of radiation crisis by the hydrogen explosion at Unit-1 reactor. During a succession of unexpected disasters, REMAT members were involved in various activities for six days, such as setting the base for radiological triage at the Fukushima Medical University, considerations for administration of stable iodine, and risk communication with health care workers. This report briefly describes what happened around REMAT members and radiation doses measured during their activities. ► The radiation emergency medical assistance team from Nagasaki was sent to Fukushima. ► The practical action level for body surface contamination was 100 kcpm. ► The ambient radiation dose in Fukushima drastically elevated on March 15, 2011. ► Higher than 10 kBq of I-131, Cs-134, and Cs-137 were detected in soil samples. ► The effective dose of the team members ranged between 51.7 and 127.8 μSv in 6 days.

Dutch distribution zones of stable iodine tablets based on atmospheric dispersion modelling of accidental releases from nuclear power plants

Rapid administration of stable iodine is essential for the saturation and subsequent protection of the thyroid gland against the potential harm caused by radioiodines. This paper proposes the Dutch risk analysis that uses an atmospheric dispersion model to calculate the size of the zones around nuclear power plants where radiological thyroid doses for children might be sufficiently high to warrant iodine administration. Dose calculations for possible releases from the nuclear power plants of Borssele (The Netherlands), Doel (Belgium) and Emsland (Germany) are based on two scenarios in combination with a 1-y set of authentic, high-resolution meteorological data. The dimensions of the circular zones were defined for each nuclear power plant. In these zones, with a radius up to 50 km, distribution of stable iodine tablets is advised.

TRANSFER OF 131I INTO HUMAN BREAST MILK AND TRANSFER COEFFICIENTS FOR RADIOLOGICAL DOSE ASSESSMENTS

Data on transfer of radioiodine into human milk are rare in the literature. Data from sixteen publications were reviewed and analyzed to estimate the transfer coefficient (f(hm)*, having units of d L(-1)). The data on the radioiodine concentration in breast milk were analyzed by two methods: direct numerical integration and integration of a fitted exponential model. In general, the integrated fitted functions were greater. The fitted functions likely better describe the transfer into milk since few data sets sampled mothers' milk near the time of maximum excretion. The derived transfer coefficient values seem to represent two populations. The first group was those individuals who had very low excretions, including those where thyroid and mammary uptake was impaired by the administration of stable iodine or iodinated compounds. The second group included those with much higher excretions. The second group, termed the "normal-excretion" group, had transfers of iodine to milk that were more than ten-fold higher than in the "low-excretion" group. The derived milk transfer coefficient data for the low- and normal-excretion groups fitted to lognormal distributions gave geometric means, (geometric standard deviations), of 0.043 d L(-1) (2.1, n = 14) and 0.37 d L(-1) (1.5, n = 12), respectively. Estimates of the effective half-time (time from maximum concentration to half the value) were determined for the low- and normal-excretion groups separately. There was evidence that the effective half-time was longer for the normal- than for the low-excretion group; the geometric mean (and geometric standard deviation) were 12 (1.7) and 8.5 (2.6) h, respectively, though the difference was not statistically significant. The geometric mean times to maximum milk concentration in the low- and normal-excretion groups were nearly identical, 9.4 (3.1) and 9.0 (1.6) h, respectively. The data show that administration of large doses of stable iodine (commonly used to block uptake of iodine into the thyroid) is also an effective means to block radioiodine transfer into milk. Thus, protecting the mother's thyroid also protects the nursing infant. Despite inadequacies of available data describing the transfer of radioiodine to human milk within a healthy population of women, the values of f(hm)* provided here are believed to be the best available for use in radiological assessments. These values are particularly applicable to lactating women having normal diets and availability to stable iodine, as in the United States.

La protection de la thyroïde de l'enfant et du fœtus en cas d'accident nucléaire

The administration of stable iodine in order to keep the thyroid gland away from radioactive iodine isotope contamination has long been regarded with caution by the health authorities, mainly because of the potential toxicity of iodine in newborns, young children and adults with thyroid pathology. Therefore, the risk of oral stable iodine given for a limited period of time must be compared to the risk of cancer due to radioactive exposure. The analysis of complications following the nuclear accidents of Marshall Islands in 1954 and Tchernobyl in 1986 has shown that newborn infants and young children have the highest risk, the main complications being cancer (papillary carcinoma) and hypothyroidism. In the most exposed areas of Bielorussia, the incidence of child thyroid cancer has been approximately multiplied by 100. On the other hand, studies of children from Utah who were contaminated after nuclear tests in the Nevada desert have shown that following mild iodine radioactive exposure, the risk is not significant. Among complications attributed to stable iodine, only those related to an oral intake over a limited period of time should be considered. On the basis of nuclear medicine experience and scientific literature, the risk can be considered as negligible in adults but not in children. However, the Polish experience in children has reported a low risk and only benign complications, mainly transient hypothyroidism. Thus from current knowledge, it appears that the potent risks linked to stable iodine administration should not contraindicate the collective preventive stable iodine administration in case of nuclear accident.

The effectiveness of oral administration of potassium iodide to lactating goats in reducing the transfer of radioiodine to milk

Ingestion of milk contaminated by radioiodine (most especially 131I) represents an important potential route of radiation exposure to humans in the event of a nuclear accident. Oral administration of stable iodine to dairy ruminants has previously been suggested as an effective countermeasure to reduce radioiodine levels in milk. However, previous data on its effectiveness are contradictory, and little attention has been given to the most appropriate time to administer stable iodine relative to the time that an animal is first exposed to radioiodine. The effectiveness of 1g KI orally administered to lactating goats 12 h before and 12 h after contamination with pulse doses of radioiodine was investigated. Administration of KI prior to the ingestion of radioiodine was shown to reduce the transfer to milk by 50% compared to a reduction of approximately 40% when KI was administered 12 h after radioiodine. The administration of KI 12 h prior to radioiodine contamination effectively reduced the transfer of radioiodine to the thyroid by approximately 90%. When administered 12 h after radioiodine, the KI stopped subsequent uptake of radioiodine by the thyroid. The maximum level of iodine in milk, as a consequence of the administration of KI, was 20 mg I kg −1. This was 40-fold higher than the maximum permissible level of iodine in milk of 0.5 mg l −1 currently set in some countries. Further consideration is required on stable iodine administration regimes for different scenarios and the consequent increase in the stable iodine content of the milk of different dairy animals.

A review of countermeasures to reduce radioiodine in milk of dairy animals.

The most effective countermeasure for radioiodine contamination of milk is to provide dairy animals with uncontaminated feed, with the added advantage that it will be effective for other radionuclides in the fallout. Another effective response is to process the milk into storable dairy products for an appropriate length of time to allow for physical decay. The use of additives given to ruminants to reduce radioiodine in milk is an alternative countermeasure which could be effective. Stable iodine administration is a practically feasible option which has the potential to reduce radioiodine levels in milk by at most a factor of three. Stable iodine supplementation should be at sufficiently high rates to be effective (and at least 1 g d-1 for dairy cows), particularly for ruminants already receiving high amounts of iodine in the diet. Currently available data are inadequate to recommend a suitable stable iodine administration rate for different species of ruminants. Other compounds, such as perchlorate and thiocyanate, also reduce the transfer to radioiodine to milk (and thyroid). Some of these compounds seem to be potentially equally as effective as stable iodine. However, currently there is inadequate information on their effectiveness and possible toxicity to both ruminants and humans for these compounds to be considered as suitable countermeasure additives.

Administration of stable iodine to the population around the Chernobyl nuclear power plant

A very large amount (2.5 × 1017 Bq) of radioactive iodine was released as a result of the Chernobyl accident in 1986. An effective protective action that may be employed to reduce the potential radiation dose to the thyroid gland after a serious nuclear reactor accident is the administration of stable iodide in the form of potassium iodide (KI).Potassium iodide was reportedly given to nearly five and a half million persons after the Chernobyl accident. During the International Chernobyl Project, medical investigators asked the general population in both highly contaminated and control settlements about thyroid prophylaxis. Only 25% of persons currently living in the most contaminated regions reported taking potassium iodide. Sixty-six percent indicated that they did not take potassium iodide and 9% were uncertain. Of those who took stable iodine prophylactically, 44% indicated that it was in solution, 44% that it was in tablets and 12% did not remember how it was administered. Only about one third of persons were able to indicate the duration of time that they took such medication. The average was 6.2 days. It appears that iodine prophylaxis will not have a major impact on estimated collective thyroid doses to the general population living around the Chernobyl nuclear power plant. The impact that distribution of KI had upon plant and emergency accident workers remains unknown to us.

Radioiodine uptakes in the thyroid. Studies of the blocking and subsequent recovery of the gland following the administration of stable iodine.

In a series of experiments during 1964 small quantities of radioiodine were given to nine volunteers and their thyroid uptakes and urinary excretion patterns studied. The effects of varying doses of stable iodine on these patterns were investigated. Models of the thyroid metabolism were slightly amplified to give satisfactory explanations of the experimental results. The minimum amount of stable iodine needed to block the thyroid uptake completely was about 30 mg. Thyroid uptake ceased within half an hour of taking the blocking dose and was back to normal about 8 days after the intake. Repeated doses of stable iodine may be given at intervals to maintain effective blocking of the gland. The required doses range from 35 mg every 12 hr to 250 mg every 48 hr.