The method of processing and the results of measurements of 131I content in the thyroids of Russian people performed in May-June 1986 are presented. The contribution of radiation from Cs radionuclides in the human body was taken into account in the processing of measurement data with an SRP-68-01 device. The greatest individual 131I content was found in the thyroids of inhabitants of the Bryansk region, up to 250-350 kBq, and in the Tula and Orel regions, up to 100 kBq. The average 131I thyroid activity in the middle of May 1986 reached 80 kBq for inhabitants of some settlements in the Bryansk region, 5-8 kBq in the Tula region and 5 kBq in the Orel region.
The 131I activity was measured in 30 human fetal thyroids in Zagreb district after the Chernobyl accident. A model of radioiodine metabolism in the mother and human fetus which takes into account the age dependence of the uptake and retention of radioiodine in the fetal thyroid was developed. Having assessed that the total intake by the average mother was about 1330 Bq, a good correlation between calculated and measured fetal thyroid activities was found (r = 0.77, P less than 0.001). The fetal thyroid dose reached the maximum of 0.43 micro Gy/Bq intake at about the fifth month of gestation. It was concluded that the risk of having a child with a harmful trait due to 131I absorbed by the mother was negligible.
The age- and sex-dependence of the 131I induced count rates is determined for the measurements performed in Ukraine after the Chernobyl accident on the thyroids of over 60,000 persons. For this, the individual measurements are scaled in such a way that the mean values over age and sex on one side and the mean values over measurement series on the other side are normalized to one. The resulting distribution of all scaled measurements is roughly log-normal. Half of them lie within a factor 1.6 of the median. 131I induced count rates have a minimum at birth year 1986, about half the value of adults. The maximum count rates with about 30% above adults are reached for males around age 16 y. The count rates are up to about 40% (at age 14-17 y) higher for males than for females. The results are within statistical uncertainties independent of the geographical area and the urban or rural nature of the settlements. Starting from the relative count rates, the age- and sex-dependence is calculated for the thyroid activities 1 mo after the accident for the integrated activities and for the doses. The dose of young children is a factor of about 6.5 higher than that of adults. Uncertainties are estimated throughout.
To prospectively study the relation between TSH and risk of hip and forearm fractures.
A population-based cohort study.
In a substudy of the second survey of the Nord Trøndelag Health Study, Norway (HUNT2, 1995-97), linked with a hospital-based fracture registry, we investigated the relation between baseline TSH and risk of hip and/or forearm fractures.
A total of 16?610 women and 8595 men aged 40 years or more, without previous self-reported thyroid disease and hip or forearm fractures.
During 12.5 years follow-up, a total of 1870 women and 342 men experienced hip or forearm fractures. Overall, there was no relation between baseline TSH and fracture risk. However, there was weak evidence that women with TSH 3.5?mU/l had a slightly increased risk of hip fractures (hazard ratio (HR) 1.30, 95% CI 0.97-1.94 and HR 1.19, 95% CI 0.93-1.52) compared with the reference group with TSH of 1.5-2.4?mU/l. Supplementary analyses showed higher hip fracture risk in women with TSH >4.0?mU/l and negative thyroid peroxidase antibodies (TPOAb) compared with the reference group (HR 1.75, 95% CI 1.24-2.46).
We found no statistically significant relation between baseline TSH and subsequent fracture risk, but the data suggest a weak positive association with hip fracture risk among women with both low and high TSH. The latter association was confined to women with negative TPOAb status.
In Sweden, iodine has been added to table salt (10 mg/kg) since 1936; this amount was increased in 1966 to 50 mg/kg.
To investigate a euthyroid Swedish population (n = 44, 60-65 years) with its entire lifespan with iodine supplementation as for 24-h 131-I uptake (24 h IU) and thyroid nodularity (thyroid scintigraphy). To compare the euthyroid 24 h IU with uptake of thyrotoxic individuals, and with observations from 1955.
The 24 h IU was used in euthyroid individuals after oral administration of 0.1 MBq/2.7 microCi radioiodine and imaging of the thyroid gland was carried out using 99mTc-pertechnetate.
In 1999-2000, the mean 24 h IU in the euthyroid individuals was 21% (range 11-33%) and the normal (central 95%) reference interval was 14-30%. Scintigraphy suggested multinodular goitre in three euthyroid individuals. In Graves' patients (n = 53, 50-65 years), the mean 24 h IU was 61% (range 29-89%). In 1955, the 24 h IU in euthyroid individuals was higher (38%, range 10-70%), while hyperthyroid patients had uptake values similar to those recorded in the present investigation (mean 62%, range 40-90%).
The population sample studied had to be small for ethical reasons. We conclude that the reference interval for 24 h IU is 14-30% in this population that had spent its entire lifespan with iodine supplementation. This is lower than that recorded in a Swedish euthyroid population half a century ago having had low-grade table-salt iodine supplementation for 20 years. Values for hyperthyroid patients, however, do not appear to have been affected likewise.
The use of external irradiation in the treatment of patients with differentiated thyroid cancer is still under consideration. The aim of the study was to compare Tef in the thyroid remnants in patients with and without external irradiation prior to radioiodine treatment. 70 patients with thyroid remnants after resection of thyroid and dissection of pathological lymph nodes were treated by I-131. Patients were divided into two groups: Group 1--with external irradiation (25-60 Gy)-21 patient, and Group 2--patients who did not received external irradiation prior to radioiodine treatment (49 patients). Activities administered ranged from 1000 to 4500 MBq. I-131 kinetics was followed daily during first 4 days after activity administration on the basis of mathematical analysis of scintigraphy. T(ef) was calculated under the assumption of exponential excretion of 131-I from remnants. It was shown that in Group 1 T(eff) = 3.87 +/- 2.5 days, in Group 2 T(eff) amounted to 2.9 +/- 2.2 days. Thus, external irradiation resulted in slowing down of 131-I excretion in thyroid remnants. The probability of the full remnants ablation after the first course of 131-I treatment (p) has been calculated. It was shown that p is higher in the Group 2 in every activity interval. Teff in sequential courses of 131-I treatment has been measured at the same patients. Thus, external irradiation influences in different way at the previously irradiated and not irradiated cells.
There is a general lack of information on the possible effects of perfluoroalkyl substances (PFASs) on thyroid hormones (THs) in wildlife species. The effects of PFASs, which are known endocrine disruptors, on the TH homeostasis in hooded seals (Cystophora cristata) have yet to be investigated. Previously, correlations were found between plasma thyroid hormone (TH) concentrations in hooded seals, and organohalogen contaminants (OHCs) and hydroxyl (OH)-metabolites. Because animals are exposed to multiple contaminants simultaneously in nature, the effects of the complex contaminant mixtures that they accumulate should be assessed. Herein, we analyse relationships between plasma concentrations of multiple contaminants including protein-associated PFASs, hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) and lipid soluble OHCs and plasma concentrations of free and total THs, i.e. triiodothyronine (FT3, TT3) and thyroxine (FT4, TT4) in hooded seal mothers and their pups. The perfluoroalkyl carboxylates (PFCAs) were the most important predictors for FT3 concentrations and TT3:FT3 ratios in the mothers. The FT3 levels decreased with increasing PFCA levels, while the TT3:FT3 ratios increased. In the pups, hexachlorocyclohexanes (HCHs) were the most important predictors for TT3:FT3 ratios, increasing with increasing HCHs levels. Additionally, perfluoroalkyl sulfonates (PFSAs) and PFCAs were important predictors for FT4:FT3 ratios in hooded seal pups, and the ratio increased with increasing concentrations. The study suggests that PFASs contribute to thyroid disruption in hooded seals exposed to complex contaminant mixtures that include chlorinated and fluorinated organic compounds.
Studies on the immediate and long-term effects of radiation on the B-system immunity of children who were affected by radiation after the Chernobyl disaster (from 1986-1992) are summarized in this paper. Complete clinical and immunological examination of more than 6000 children have been carried out. The dynamics of the immune system, with ongoing reactions of cell proliferation and differentiation, gene amplification, transcription, translation, biosynthesis and switching production of isotypes and subclasses of immunoglobulins, as well as specific and nonspecific (natural) antibodies, make it highly susceptible to the action of radiation in addition to other ecological factors. B-system of immunity (B-cel level, concentration of immunoglobulins-M, G, A, E; subclasses of IgG (IgG1-IgG4) in the serum and saliva, and the level of nonspecific heterophilic autoantibodies (RF, antithyroglobulin) were investigated in children of differing ages and sex living in the territories of the Republic of Belarus contaminated with radionuclides. Research showed decreased levels of B-cell and IgM and IgG isotopes 40-50 days after the disaster and increased levels of IgA immunoglobulins at that time. Long-term effects of low doses of radiation showed increased concentrations of IgM and IgG, correlating changes in the B-system of immunity with the level of 137Cs contamination in the territory of residence and also with the amount of 137Cs found in the children.
An assessment of effectiveness of the administering of single dose of stable iodine in Poland on the reduction of 131I doses in thyroid has been performed. 5-compartment model of metabolism of iodine developed by Johnson has been used to evaluate predicted levels of stable iodine and 131I content in thyroid and commitment dose equivalent H50 for different doses of stable iodine and various age and sex group population. The measured values of 131I concentration in air and in milk and standard values for milk and food consumption and inhalation rate as well as metabolic parameters were used. Theoretical calculations showed that administering of stable iodine on 1986-04-28, 1986-04-29, 1986-04-30 and 1986-05-01 could have reduced committed dose equivalent H50 form ingestion with inhalation pathway by about 44%, 40%, 26%, 12% respectively. On the basis of measured 131I activity in the thyroid for inhabitants from different districts in Poland (1400 measurement) committed dose equivalents were determined and analysis of radiation hazard from 131I were performed. In the most contaminated regions of Poland average H50 doses for children 1-5 and 5-10 years old are close to 50 mSv (permissible level for population) and maximal doses exceed this limit four times. These maximal doses occurred for about from 5% inhabitants from these area. In the moderate and low contaminated regions of Poland the average doses are fivefold and tenfold less respectively.