Association between exposure to radioactive iodine after the Chernobyl accident and thyroid volume in Belarus 10-15 years later

Background While there is a robust literature on environmental exposure to iodine-131 (131I) in childhood and adolescence and the risk of thyroid cancer and benign nodules, little is known about its effects on thyroid volume. Methods To assess the effect of 131I dose to the thyroid on the volume of the thyroid gland, we examined the data from the baseline screening of the Belarusian-American Cohort Study of residents of Belarus who were exposed to the Chernobyl fallout at ages ≤18 years. Thyroid dose estimates were based on individual thyroid activity measurements made shortly after the accident and dosimetric data from questionnaires obtained 10-15 years later at baseline screening. During baseline screening, thyroid gland volume was assessed from thyroid ultrasound measurements. The association between radiation dose and thyroid volume was modeled using linear regression where radiation dose was expressed with power terms to address non-linearity. The model was adjusted for attained age, sex, and place of residence, and their modifying effects were examined. Results The analysis was based on 10,703 subjects. We found a statistically significant positive association between radiation dose and thyroid volume (P < 0.001). Heterogeneity of association was observed by attained age (P < 0.001) with statistically significant association remaining only in the subgroup of ≥18 years at screening (P < 0.001). For this group, increase in dose from 0.0005 to 0.15 Gy was associated with a 1.27 ml (95% CI: 0.46, 2.07) increase in thyroid volume. The estimated effect did not change with increasing doses above 0.15 Gy. Conclusions This is the first study to examine the association between 131I dose to the thyroid gland and thyroid volume in a population of individuals exposed during childhood and systematically screened 10-15 years later. It provides evidence for a moderate statistically significant increase in thyroid volume among those who were ≥ 18 years at screening. Given that this effect was observed at very low doses and was restricted to a narrow dose range, further studies are necessary to better understand the effect.

The BRAFV600E Mutation Is Not a Risk Factor for More Aggressive Tumor Behavior in Radiogenic and Sporadic Papillary Thyroid Carcinoma at a Young Age

Histopathological changes in the fusion oncogene-driven papillary thyroid carcinomas (PTCs) from children and adolescents exposed to Chernobyl fallout have been extensively studied. However, characteristics of the radiogenic BRAFV600E-positive PTCs, whose proportion is growing with time, are not well described yet. We analyzed the relationship between the BRAFV600E status (determined immunohistochemically with the VE1 antibody) and the clinicopathological features of 247 radiogenic and 138 sporadic PTCs from young Ukrainian patients aged ≤28 years. The frequency of BRAFV600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAFV600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAFV600E-negative tumors. Comparison of the BRAFV600E-positive PTCs across the groups found a virtual absence of differences. In contrast, the BRAFV600E-negative radiogenic PTCs displayed less frequent dominant papillary and more frequent solid growth patterns, lower Ki67 labeling index, and higher invasiveness than the BRAFV600E-negative sporadic tumors. Thus, BRAFV600E is not associated with a more aggressive course of PTC in young patients regardless of etiology. The major clinicopathological differences between the radiogenic and sporadic PTCs are observed among the BRAFV600E-negative tumors.

Development and characterization of a mobile γ spectrometer and its field deployment for in situ radioactivity measurements

A mobile γ–ray spectrometer (AMESOS) has been developed using a 3”×3” NaI(Tl) detector, a custom–made mounting holder, and portable electronics to perform in situ measurements of radioactivity. The spectrometer was calibrated using standard point sources and its absolute efficiency was determined. As a field test operation, AMESOS was deployed on the premises of the University of Athens Zografou campus focusing on estimating the NORM levels. Data were analyzed and used to create radiological maps for the metropolitan UoA campus for the first time. Besides natural radioactivity levels, trace concentrations of 137Cs were also detected, attributed to the Chernobyl fallout in Greece. An overall steady performance of the spectrometer was observed throughout the field operation. AMESOS is ready to be deployed for in situ studies of environmental radioactivity and radwaste management.

Updated Incidence of Thyroid Cancer in the North East Region of Romania after 35 Years of Chernobyl Fallout. Is There a Link between?

Thyroid cancer (TC) represents a worldwide problem, the consistent growth of the incidence increment issues about management of risk factors and curative treatment. Updated statistical data are not complete in the North East region of Romania and need to be improved. Therefore, through this study, we aim to renew the existing data on thyroid cancer. We conducted a retrospective study covering a period of 10 years. Data were collected from a hospital information system (InfoWorld) between 2009 and 2019. Patients’ age groups were stratified in relation with the age at the moment of the Chernobyl event. A database was obtained (Microsoft Excel) and statistical correlations were applied. In the studied period, 1159 patients were diagnosed: 968 females and 191 males, distributed by region, with the highest addressability in Iasi (529), followed by neighboring counties. Age distribution displayed that most of the thyroid cancers were in the range 4060 years old (50.94%), followed by 60–80 years old (32.41%). Most patients were diagnosed with papillary carcinoma 63.10%, then follicular 14.7%, medullary 6.74% and undifferentiated 1.02%. Romania was in the vicinity of the radioactive cloud at Chernobyl fallout, so we must deliberate whether the increased incidence of thyroid cancer in the age group 40–60 years is associated with radiogenicity (iodine 131) given the fact that over has 35 years and the half-life of other radioisotopes like Caesium-137 and Strontium -90 is completed.

A review of worldwide sediment core dating research including fallout radiocaesium (137Cs)

&lt;p&gt;Dating recent sediment archives (&lt;150 years) constitutes are need for environmental and climatic reconstructions. Radiocaesium (&lt;sup&gt;137&lt;/sup&gt;Cs) emitted during thermonuclear bombs testing (~1950 - ~1980) and nuclear accidents (1986 and 2011) was generally used for identifying sediment sources or for establishing sediment core chronology based on discrete time markers. Although this method was widely used during the last several decades, there is a lack of structured and comprehensive worldwide synthesis of radiocaesium fallouts. The current literature overview was based on 573 articles published between 1977 and 2020, reporting the collection of 1351 individual dated sediment cores. This synthesis led to the identification of the worldwide distribution of discrete time markers associated with the thermonuclear bomb testing peak in 1963, the Chernobyl fallout, the Fukushima fallout, as well as the identification of at least 25 events induced by local accidents or nuclear tests (e.g. Sellafield, la Hague accidents, Chinese nuclear tests).&lt;/p&gt;&lt;p&gt;With a growing number of studies focusing on the analysis of recent sediment cores and the increasing interest in sediment fingerprinting techniques, this spatialized synthesis provides a unique worldwide referential for identifying the distribution of the &lt;sup&gt;137&lt;/sup&gt;Cs sources at global scale. It also outlines the main questions that would deserve attention in future research perspectives and the regions where &lt;sup&gt;137&lt;/sup&gt;Cs fallouts investigations should be conducted in priority.&lt;/p&gt;

Environmental radioactivity studies at the Nuclear Engineering Laboratory of the National Technical University of Athens

&lt;p&gt;The Nuclear Engineering Laboratory of the National Technical University of Athens (NEL-NTUA) is among the oldest laboratories conducting radioactivity mesurements in Greece, founded in the early sixties. One of the main activities at NEL-NTUA is environmental radioactivity studies, mainly based on gamma spectroscopic analysis. For this purpose NEL-NTUA is equipped with a variety of Germanium detectors for in-vitro and in-situ measurements. Starting back in the early eighties, environmental radioactivity studies at NEL-NTUA were significantly boosted after the Chernobyl accident in 1986&amp;#160; when they focused on the Chernobyl fallout radionuclides, as well as some natural radionuclides typically determined in environmental studies, namely &lt;sup&gt;232&lt;/sup&gt;Th, &lt;sup&gt;226&lt;/sup&gt;Ra and &lt;sup&gt;40&lt;/sup&gt;K. As a result of these studies maps of nine Chernobyl fallout radionuclides and the three natural radionuclides in continental Greece surface soils were produced.&amp;#160;&lt;/p&gt;&lt;p&gt;Since natural radioactivity in soil is in most cases relatively low, high volume samples had to be analyzed. Over the years, the acquisition of detectors capable of detecting low energy photons (LEGe) along with the development of techniques to correct for self-absorption of low energy photons within the sample, allowed for the accurately determination of radionuclides emitting such photons, like &lt;sup&gt;234&lt;/sup&gt;Th (63.29keV), &lt;sup&gt;210&lt;/sup&gt;Pb (46.52keV) and &lt;sup&gt;241&lt;/sup&gt;Am (59.54keV). These newer studies showed that a significant disruption of radioactive equilibrium in surface soil between &lt;sup&gt;226&lt;/sup&gt;Ra and &lt;sup&gt;210&lt;/sup&gt;Pb is very common, while radioactive equilibrium disruption between &lt;sup&gt;238&lt;/sup&gt;U and &lt;sup&gt;226&lt;/sup&gt;Ra is common as well. It is interesting to notice that the mean activity ratio &lt;sup&gt;210&lt;/sup&gt;Pb/&lt;sup&gt;226&lt;/sup&gt;Ra as obtained from ~300 sample measurements is of the order of ~4, while the mean activity ratio&lt;sup&gt; 226&lt;/sup&gt;Ra/&lt;sup&gt;238&lt;/sup&gt;U was estimated to be around one. A mapping of radioactive equilibrium disruption that followed provided interesting results.&lt;/p&gt;&lt;p&gt;In the years to follow studies focused on the vertical distribution of natural (&lt;sup&gt;210&lt;/sup&gt;Pb) and artificial (&lt;sup&gt;137&lt;/sup&gt;Cs) radionuclides in soil and sea sediments and the study of radionuclides fractionation in soil as well as NORM. Both types of studies require the analysis of small volume samples &amp;#8211; of the order of 20-50g or even less. Therefore, the development of techniques for sampling of soil vertical profile and the accurate analysis of small samples was of great importance. These analyses require high efficiency detectors, such as XtRa detectors, background reduction techniques, such as Compton Suppression Systems, optimized sample geometries for higher full energy peak efficiency. Sophisticated techniques for background determination and subtraction, in order to obtain accurate results for natural radionuclides which are often detected in the background, are also required.&lt;/p&gt;&lt;p&gt;Another field of research at NEL-NTUA is the development and improvement of techniques for monitoring of &lt;sup&gt;222&lt;/sup&gt;Rn daughters outdoors using on-line detector systems, as well as for monitoring of natural and artificial radionuclides in atmospheric precipitations and aerosols (&lt;sup&gt;7&lt;/sup&gt;Be, &lt;sup&gt;210&lt;/sup&gt;Pb, &lt;sup&gt;22&lt;/sup&gt;Na) using high volume air samplers.&lt;/p&gt;&lt;p&gt;Aim of this work is to present the research conducted at NEL-NTUA over the years with regard to the environmental radioactivity, as well as the current activities&amp;#160;in the field and those planned for the future.&lt;/p&gt;

Differentiated Thyroid Cancer in Children in the Last 20 Years: A Regional Study in Romania

Pediatric thyroid carcinoma is a current area of interest, because there are few studies in this field; the current classification and treatment guidelines are extrapolated from adults, sometimes leading to overly aggressive treatments or incomplete treatment of the disease. The purpose of this retrospective study is to analyze the presentation, diagnosis, treatment, complications, and outcome of children diagnosed with thyroid cancer in the last two decades (2000–2018) at the Oncological Institute “Prof. Dr. Ion Chiricuță” Cluj-Napoca (IOCN) Romania, a tertiary center in a region with environmental influences from both the nuclear fallout of the Chernobyl accident and from iodine deficiency. The results were compared with those obtained in a previous study carried out in the same institution between 1991–2010, and with those obtained in a similar study carried out in Netherlands between 1970–2013, a cohort of children not exposed to the post-Chernobyl fallout. We statistically analyzed 62 patients. Papillary form was present in the majority of cases, and we highlighted the occurrence of thyroid microcarcinoma in children. A total of 85.4% of patients received radioiodine, the total activity being significantly lower compared with the data from literature. In our study, the prognosis of the disease was excellent, with 100% overall survival.