Distribution Of 131I Research Articles

Spatiotemporal variation of radionuclide dispersion from nuclear power plant accidents using FLEXPART mini-ensemble modeling

Abstract. We investigate the spatiotemporal distribution of the radionuclides including iodine-131 (131I) and cesium-137 (137Cs), transported to Qatar from fictitious accidents at the upwind Barakah nuclear power plant (B-NPP) in the United Arab Emirates (UAE). To model the dispersion of radionuclides, we use the Lagrangian particle–air parcel dispersion model FLEXible PARTicle (FLEXPART) and FLEXPART coupled with the Weather Research and Forecasting model (FLEXPART–WRF). A four-member mini-ensemble of meteorological inputs is used to investigate the impact of meteorological inputs on the radionuclide dispersion modeling. The mini-ensemble includes one forecast dataset (Global Forecast System, GFS) and three (re)analysis datasets (native-resolution and downscaled NCEP final analysis – FNL, as well as downscaled ERA5). Additionally, we explore the sensitivity of the radionuclide dispersion simulations to variations in the turbulence schemes, as well as the temporal and vertical emission profiles, and the location of emission sources. According to the simulated age spectrum of the Lagrangian particles, radionuclides enter southern Qatar about 20 to 30 h after release. Most of the radionuclide deposition in the study area occurs within 80 h after release. The most populated areas of Qatar coincide with moderate 131I concentrations and 137Cs deposition, while uninhabited areas in southern Qatar receive the highest amounts. A larger number of long-lived particles is found in the FNL-based simulations, which is interpreted as a greater dispersion of particles at a greater distance from the emission location. The highest simulated 131I and 137Cs deposition shows a pronounced spatiotemporal pattern. The largest impacts are found in the south and southeast of Qatar, during the early daytime development of the boundary layer, and during the cold period of the year. The results show remarkable differences in the spatiotemporal distribution of 131I and 137Cs simulations based on the FNL and GFS datasets, which share a common base meteorological model. As part of a sensitivity analysis involving different model setups, changing the emission point from B-NPP to Bushehr NPP (Bu-NPP) results in a reduced transfer of radioactive materials to Qatar, except in the spring season. Bu-NPP simulations reveal distinct spatial patterns, with peak 131I concentrations and 137Cs deposition observed in northern and eastern Qatar during winter and spring.

Analysis of factors influencing the distribution of 131-I in combined treatment of Licartin with transcatheter arterial chemoembolization in primary hepatic carcinoma.

To analyze the factors influencing the distribution of 131-I in the liver of patients with advanced hepatic carcinoma treated with the combination of Licartin (131I Metuximab) and transcatheter arterial chemoembolization (TACE). This study provides a reference and basis for the clinic on how to choose the best time for the treatment of Licartin and how to reduce other possible factors affecting the role of Licartin. Data from 41 patients with advanced hepatic carcinoma treated with the combination of Licartin and TACE in the Interventional Department of our hospital from March 2014 to December 2020 were collected. This included general characteristics, history of open and interventional surgery, interval between the last interventional surgery and the Licartin treatment, selected arteries in the Licartin perfusion, and 131-I distribution in the liver. Regression analysis was conducted to investigate the factors affecting the distribution of 131I in the liver. In 14 cases (34.1%), 131-I was evenly distributed in the liver, and there was no correlation between the cause of even distribution with age(OR=0.961, P = 0.939), previous open surgery history(OR=3.547,P= 0.128), previous history of interventional therapy(OR=0.140,P = 0.072), the interval between the last interventional surgery and the Licartin treatment(OR=0.858,P = 0.883), or the choice of the perfusion artery in the Licartin treatment (OR=1.489,P = 0.419). In 14 cases (34.1%), there was higher aggregation in the tumor than in the normal liver, which was related to previous interventional surgery (OR=7.443,P = 0.043). In 13 cases (31.7%), there was lower aggregation in the tumor than in the normal liver, which was related to the selected vessels in the Licartin perfusion (OR=0.23,P = 0.013). The effective aggregation of 131-I in the liver, even in tumors, the previous history of TACE, and the choice of vessels in the Licartin infusion might be the factors influencing the distribution of 131-I in the liver during hepatic artery infusion of Licartin in combination with TACE therapy.

In memoriam: John R. Mallard (1927-2021).

In memoriam: John R. Mallard (1927-2021).

The physicochemical distribution of 131I in a municipal wastewater treatment plant

As a consequence of therapeutic and diagnostic treatment of patients with thyroid diseases, 131I is introduced into the sewage system on a regular basis. This presents an opportunity to use the 131I as a tracer to study its partitioning and transport within a wastewater treatment plant (WWTP). In the case of nuclear accidents where 131I is one of the most prominent nuclides, an understanding of iodine partitioning and transport will be valuable for developing models that may prognosticate the activity concentrations in sludge and outflow, especially after an accidental input. In this study, samples from various locations inside a municipal WWTP were taken and for each sample, three different fractions were separated by a chemical extraction process. These fractions were analysed for their 131I activity concentrations by gamma-ray spectroscopy. While about 30% of the radioiodine activity in the inflow is associated with organic molecules, this amounts to about 90% after biological treatment. This is caused by the accumulation of 131I bound to organic matter in the return sludge and by a transfer of 131I from the inorganic to the organic fractions, most likely mediated by microbial action. In the outflow, inorganic and low-molecular 131I is dominant, but the overall activity concentration is reduced to about 50–75%.

Assessment of the Point-Source Method for Estimating Dose Rates to Members of the Public from Exposure to Patients with 131I Thyroid Treatment.

The U.S. Nuclear Regulatory Commission (USNRC) initiated a contract with Oak Ridge National Laboratory (ORNL) to calculate radiation dose rates to members of the public that may result from exposure to patients recently administered iodine-131 (131I) as part of medical therapy. The main purpose was to compare dose rate estimates based on a point source and target with values derived from more realistic simulations of a human source and target. The latter simulations considered the time-dependent distribution of 131I in the patient and attenuation of emitted photons by the patient's tissues. The external dose rate estimates were derived using Monte Carlo methods and two representations of the Phantom with Movable Arms and Legs (PIMAL), previously developed by ORNL and the USNRC, to model the patient and a nearby member of the public. Dose rates to tissues and effective dose rates were calculated for distances ranging from 10 cm to 300 cm between the phantoms. Dose rates estimated from these simulations are compared to estimates based on the point-source method, as well as to results of previous studies that estimated exposure from 131I patients. The point-source method overestimates dose rates to members of the public in very close proximity to an 131I patient but is a broadly accurate method of dose rate estimation at separation distances of 300 cm or more at times closer to administration.

S values for 131I based on the ICRP adult voxel phantoms.

To improve the estimates of organ doses from nuclear medicine procedures using (131)I, the authors calculated a comprehensive set of (131)I S values, defined as absorbed doses in target tissues per unit of nuclear transition in source regions, for different source and target combinations. The authors used the latest reference adult male and female voxel phantoms published by the International Commission on Radiological Protection (ICRP Publication 110) and the (131)I photon and electron spectra from the ICRP Publication 107 to perform Monte Carlo radiation transport calculations using MCNPX2.7 to compute the S values. For each phantom, the authors simulated 55 source regions with an assumed uniform distribution of (131)I. They computed the S values for 42 target tissues directly, without calculating specific absorbed fractions. From these calculations, the authors derived a comprehensive set of S values for (131)I for 55 source regions and 42 target tissues in the ICRP male and female voxel phantoms. Compared with the stylised phantoms from Oak Ridge National Laboratory (ORNL) that consist of 22 source regions and 24 target regions, the new data set includes 1662 additional S values corresponding to additional combinations of source-target tissues that are not available in the stylised phantoms. In a comparison of S values derived from the ICRP and ORNL phantoms, the authors found that the S values to the radiosensitive tissues in the ICRP phantoms were 1.1 (median, female) and 1.3 (median, male) times greater than the values based on the ORNL phantoms. However, for several source-target pairs, the difference was up to 10-fold. The new set of S values can be applied prospectively or retrospectively to the calculation of radiation doses in adults internally exposed to (131)I, including nuclear medicine patients treated for thyroid cancer or hyperthyroidism.

Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents

Following the Fukushima accident, a series of aerosol samples were taken between 24th March and 13th April 2011 by cascade impactors in the Czech Republic to obtain the size distribution of 131I, 134Cs, 137Cs, and 7Be aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for 7Be were 0.43 and 0.41 μm with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of 134Cs, 137Cs and 7Be in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to 131I increased at a significance level of 0.1. Results obtained after the Fukushima accident were compared with results obtained after the Chernobyl accident. The radionuclides released during the Chernobyl accident for which we determined the AMAD fell into two categories: refractory radionuclides (140Ba, 140La 141Ce, 144Ce, 95Zr and 95Nb) and volatile radionuclides (134Cs, 137Cs, 103Ru, 106Ru, 131I, and 132Te). The AMAD of the refractory radionuclides was approximately 3 times higher than the AMAD of the volatile radionuclides; nevertheless, the size distributions for volatile radionuclides having a mean AMAD value of 0.51 μm were very close to the distributions after the Fukushima accident.

Correlation between Micronuclei Frequency in Peripheral Blood Lymphocytes and Retention of 131-I in Thyroid Cancer Patients

Differentiated thyroid cancers (DTCs) derive from thyroid follicular cells and include papillary and follicular cancers. In patients with DTCs, the initial treatment includes thyroidectomy and radioactive iodine (131-I) therapy. The objective of this study was to examine whether the intensity of DNA damage in peripheral blood lymphocytes (PBLs) of DTC patients depends on the amount of 131-I retained in the selected regions of interest (thyroid and abdominal region) as well as in the whole-body 72 hours after therapy. In addition, the possible influence of other factors that may affect micronuclei (MN) frequency, such as age, gender, smoking habits, and histological type of tumour was analyzed. The study population consisted of 22 DTC patients and 20 healthy donors. Data on the distribution of 131-I were obtained from the whole-body scans. MN frequency and cytokinesis-block proliferation index (CBPI) were measured using cytokinesis-block micronucleus assay. 131-I therapy significantly increased the MN frequency (19.50±6.90 vs. 27.10±19.50 MN) and significantly decreased the CBPI (1.52±0.20 vs. 1.38±0.17) in patients' lymphocytes. There was a clear correlation between the increased MN frequency and 131-I accumulation in the thyroid region in patients without metastases. The MN values did not differ in relation to the factors that could affect MN, such as age, gender, smoking habits, and histological type of tumour. In conclusion, the MN frequency in PBLs of DTC patients without metastases depends on the accumulation of 131-I in the thyroid region and does not depend on the other factors examined.

Distribution of 131I, 134Cs, 137Cs and 239,240Pu concentrations in Korean rainwater after the Fukushima nuclear power plant accident

Radionuclides such as 131I, 134Cs, 137Cs, and 239,240Pu in Korean rainwater have been analyzed by Korea Research Institute of Standards and Science (KRISS) since the Fukushima nuclear power plant accident in March 2011 to investigate the activity level, distribution pattern, and temporal variation and to assess the radiation dose the public is exposed to. The concentration of 131I in the Korean rainwater samples varied between 0.033 (minimum detectable activity; MDA) and 1.30 Bq kg−1 and the concentrations tended to decrease exponentially with time. The concentrations of 134Cs and 137Cs in rainwater ranged from 0.01 to 334 ± 74 and 0.29 ± 0.01 to 276 ± 1 mBq kg−1, respectively. The mean activity ratio of 137Cs/134Cs in the rainwater samples collected from April 18 to May 12 was estimated to be 0.44 ± 0.21, and this value is lower than that (ca. 1) observed in Fukushima, Japan, when there was an escape from the nuclear reactors. When an attempt was made to analyze Pu isotopes in rainwater samples, no Pu isotopes were detected above the MDA in any of the rainwater samples. Although the locations investigated were different from Asia to Europe, the concentrations of 131I, 134Cs and 137Cs in the rainwater are comparable, which suggests a global contamination of 131I, 134Cs, and 137Cs occurred because of the Fukushima nuclear power plant accident.

Dose distribution of 131I, 132I, 133I, 134I, and 135I due to a hypothetical accident of TRIGA Mark-II research reactor.

An attempt has been made in the work to assess radiological dose due to the deposition of 131 I, 132 I, 133 I, 134 I, and 135 I on ground, vegetation, milk and meat considering a hypothetical accident of TRIGA Mark-II research reactor at AERE, Savar. Contribution of dose from ingestion of vegetation due to 131 I has been found to be dominant (62.96%). Also found that contribution of 132 I from immersion is higher (53.67%) and contribution of 133 I in meat is higher (45.64%). The contribution due to 134 I in both from immersion (46.13%) and from ground deposition (47.19%) was dominant while the contribution of 135 I from ground deposition (30.11%), inhalation (26.77%) and immersion (25.92%) were higher. Final result says that the vegetation is the dominant contributor (66.91%) for iodine.

Utility of Additional Delayed Post-Therapeutic 131I Whole-Body Scanning in Patients With Thyroid Cancer

The purpose of this study is to compare early (3 days after administration) and delayed (7-9 days after administration) post-therapeutic ¹³¹I scanning for detecting metastatic lesions from differentiated thyroid carcinoma. This study included 24 patients (10 men and 14 women) with differentiated thyroid carcinoma who underwent early and delayed whole-body scanning after ¹³¹I treatment. The early and delayed scan images were visually analyzed, and the region-to-whole-body ratio (RBR) and its variation from the early to delayed scanning (RBR variation) were calculated. In the visual analysis, lung metastases in 2 patients and 1 bone metastasis could not be detected on early scanning but were classified as moderate uptake on delayed scanning. The abdomen showed definite uptake on early scanning but was washed out on delayed scanning. The RBR variation of the lung and bone metastases was significantly higher than those of the abdomen and thyroid remnants. This suggests that the distribution of ¹³¹I was more quickly washed out of the abdomen and thyroid remnants than from the metastatic lesions. Delayed scanning showed a higher detection rate of lung and bone metastases than early scanning because of the washout of the physiological distributions. Additional delayed scanning is recommended, especially for high-risk patients with intensive physiological distribution on early scanning.

Diffusion of Radioactive Materials from Fukushima Daiichi Nuclear Power Station Obtained by Gamma-Ray Measurements on Expressways

In Fukushima and neighboring prefectures, the distributions of dose rate and γ-ray count rate of radionuclides from the Fukushima Daiichi Nuclear Power Station were measured on expressways on March 15, 16, 17, and April 8, 2011, using an NaI(Tl) detector and a LaBr3 detector. A radioactive plume that contained 133Xe, 132Te, 132I, 131I, 134Cs, and 136Cs was observed at Koriyama on the afternoon of March 15. The plume arrived in the Nakadori region of Fukushima prefecture, which is surrounded by two mountain ranges, and most of the radioactivity there was deposited by rainfall. Although the distributions of 132Te, 132I, 134Cs, 136Cs, and 137Cs were similar, the distribution of 131I was different from the others. The effective nuclides for the dose rate measurement were 132Te and 132I on March 15-17 and 134Cs and 137Cs on April 8. The initial distribution profile of the dose rate on March 15-17 was retained on April 8 because the deposited radioactive material was not moved from the initial location and there was no additional effective deposition of radioactivity.

Modeling Multicellular Response to Nonuniform Distributions of Radioactivity: Differences in Cellular Response to Self-Dose and Cross-Dose

Radiopharmaceuticals are distributed nonuniformly in tissue. While distributions of radioactivity often appear uniform at the organ level, in fact, microscopic examination reveals that only a fraction of the cells in tissue are labeled. Labeled cells and unlabeled cells often receive different absorbed doses depending on the extent of the nonuniformity and the characteristics of the emitted radiations. The labeled cells receive an absorbed dose from radioactivity within the cell (self-dose) as well as an absorbed dose from radioactivity in surrounding labeled cells (cross-dose). Unlabeled cells receive only a cross-dose. In recent communications, a multicellular cluster model was used to investigate the lethality of microscopic nonuniform distributions of 131I iododeoxyuridine (131IdU). For a given mean absorbed dose to the tissue, the dose response depended on the percentage of cells that were labeled. Specifically, when 1, 10 and 100% of the cells were labeled, a D37 of 6.4, 5.7 and 4.5 Gy, respectively, was observed. The reason for these differences was recently traced to differences in the cellular response to the self- and cross-doses delivered by 131IdU. Systematic isolation of the effects of self-dose resulted in a D37 of 1.2 +/- 0.3 Gy. The cross-dose component yielded a D37 of 6.4 +/- 0.5 Gy. In the present work, the overall survival of multicellular clusters containing 1, 10 and 100% labeled cells is modeled using a semi-empirical approach that uses the mean lethal self- and cross-doses and the fraction of cells labeled. There is excellent agreement between the theoretical model and the experimental data when the surviving fraction is greater than 1%. Therefore, when the distribution of 131I in tissue is nonuniform at the microscopic level, and the cellular response to self- and cross-doses differs, multicellular dosimetry can be used successfully to predict biological response, whereas the mean absorbed dose fails in this regard.

Dosimetry of Phase I/II study of intracavitary administered I-131-TM-601 peptide in patients with recurrent high-grade glioma

Postoperative radiotherapy for glioma has been shown benefit to improve survival with increased radiation doses. Dose from external beam radiotherapy is limited by normal brain toxicity. Brachytherapy can deliver higher radiation doses contained within short distance near the implants. However, traditional solid source implants require a second invasive procedure, and often fail to tailor the dose distribution to the target volume. One novel approach is to use radiolabeled target molecules to penetrate and deliver localized radiation to the tumor cells. TM-601 is a peptide derived from the venom of the scorpion that specifically binds to malignant brain tumors. This study reports dosimetry results of a recent Phase I/II study, in which 10 mCi of I-131-TM-601 peptide was directly infused into the resected tumor cavity. TM-601, or Chlorotoxin, (TransMolecular, Inc. Birmingham, AL) is a, 36 amino acid, peptide derived from the venom of the scorpion Leiurus Quinquestriatus. 18 patients with recurrent high-grade glioma received single injection of 10 mCi, 0.25–1.00 mg I-131-TM-601 into surgically created resection tumor cavities. At immediate and up to 168 hr post injection, sequential 5 whole body gamma camera images were acquired for normal organ I-131 quantification and 5 SPECT images were acquired for tumor cavity wall I-131 quantification. Attenuation correction for geometric-mean quantification was determined using Co-57 transmission scan. Peak tissue uptake of I-131-TM-601 was expressed as % injection dose (%ID) and clearance half time was fitted with mono-exponential curve. Radiation doses to normal organs were based on Medical Internal Radiation Dose (MIRD) formalism. Radiation dose to bone marrow was determined for electron radiation from I-131 in the blood and photon radiation from body. SPECT images were registered with CT/MRI using external fiducial markers to determine I-131-TM-601 distribution in 2-cm tumor cavity wall. I-131 distribution in cavity wall were converted to dose rate distribution using 3-D dose convolution at 5 time points. I-131-TM-601 quickly penetrated through tumor cavity wall. At 24 hour post injection, 79% (mean, range 44–99%) of injected I-131-TM-601 left tumor cavity. I-131-TM-601 was cleared out of body through urinary tract. Apart from tumor cavity, bladder, kidneys, stomach/spleen, and thyroid were visualized above body background in gamma camera images. Mean peak %ID was 2 (range 0.5–5) % for stomach/spleen, 2 (range 0.5–6.5) % for kidneys, 0.2 (range 0.1–1.1) % for thyroid, and 3 (range 1–5) % for normal half of the brain. Mean peak blood concentration was 0.2 (range 0.1–0.4) uCi/ml. Mean biological half-life, Tbio1/2, was 47 (range 31–81) hr for body, 25 (range 17–40) hr for stomach/spleen, 26 (18–39) hr for kidneys, and 42 (range 21–80) hr for normal half of the brain. 12 patients had Tbio1/2 of 35–2600 hr for thyroid, the remaining 6 patients showed no clearance in thyroid uptake within 168 hr observation. The mean beta phase clearance was 29 (range 14–41) hr for blood. Mean radiation dose (cGy/mCi) was 0.4 (range 0.2–0.7) for whole body, 0.7 (range 0.2–1.3) for stomach, 0.9 (range 0.3–1.8) for kidneys, 5.3 (range 0.8–22.9) for thyroid, 0.3 (range 0.1–0.4) for bone marrow, and 1.1 (range 0.3–2.4) for normal half of the brain. Radiation doses in 2-cm cavity wall were non-uniform. Mean radiation doses to 2-cm tumor cavity wall were ranged 25–260 cGy/mCi. The ratio of mean tumor wall dose-to-normal half of the brain dose ranged 60–260. I-131-TM-601 has a high tumor wall dose-to-normal tissue dose index. Dosimetric data suggest that large amount of radiation dose can be delivered to kill residual tumor cells without normal tissue toxicity. These promising results suggest potential in improving patient outcome using this novel target molecule

Administration of a single dose of recombinant human thyrotrophin enhances the efficacy of radioiodine treatment of large compressive multinodular goitres

Patients with very large multinodular goitres, frequently found among elderly people, often suffering from cardiovascular or other disabling disorders, may be considered as unsuitable for surgery. We have evaluated the feasibility of relatively high-dose 131I therapy in such patients. As subclinical or clinical hyperthyroidism is commonly found in these patients, associated with a low radioiodine (RAI) uptake at 24 h, we pretreated a group of patients with a single intramuscular injection of recombinant human TSH (rhTSH 0.45 mg) in order to increase the uptake of the therapeutic dose of RAI. Forty-one patients with large, long-standing multinodular goitres, were recruited for this study. After a careful and detailed clinical and laboratory evaluation, 34 patients (28 women, six men) were included and randomly assigned to group 1 (control, n = 17, 15 women, two men, age 63.1 +/- 11.2 years) receiving only RAI. Patients in group 2 (n = 17, 13 women, four men, age 63.6 +/- 12.3 years) received the therapeutic dose of RAI, having been pretreated (24 h) with 0.45 mg of rhTSH. Both groups of patients were submitted to a low iodine diet, 4-6 months before RAI treatment, while seven thyrotoxic patients also received methimazole (40 mg/day) until they reached euthyroidism. Ultrasonographic studies were performed for all patients and fine-needle aspiration biopsy (FNAB) were performed on one or two nodules before RAI treatment. RAI was given as a single oral dose to the hospitalized isolated patients. Blood samples for thyroid function tests and serum thyroglobulin (Tg) were collected daily during the first week following RAI treatment, and at 1, 3, 6, 9 and 12 months thereafter. Goitre volume was estimated by computed tomography scan. Thyroid function tests (total T3, free T4, TSH and serum Tg) were assayed with commercial kits. Urinary excretion of iodine was assayed by the Sandell-Kolthoff method. After the RAI therapeutic dose, serum thyroid function tests were carried out daily for the first week and then on a monthly basis (1, 3, 6, 9 and 12 months). Serum TSH levels rose to a peak level of 45.9 +/- 19.1 mU/l (24 h) in group 2 returning to normal at 72 h. Free T4 serum concentrations rose significantly to 59.35 +/- 21.61 pmol/l at 48 h (in group 2) returning to normal at 7 days. Similarly, serum TT3 also peaked above normal levels only in group 2 (6.12 +/- 1.89 nmol/l) at 24 h. Serum Tg increased in both groups (significantly higher in group 2) and remained elevated during the following 12 months. Both groups had a significant reduction in goitre volume at 12 months (group 2: 57.8%vs. group 1: 39.7%, P < 0.05). Hypothyroidism was detected after RAI treatment, respectively, in 21.4% (group 1) and 64.7% (group 2), of the patients at 12 months. Our results indicate that the use of hTSH increased the efficacy of the RAI therapeutic dose. This was basically due to an increased uptake of the radionuclide (as a consequence of the higher serum TSH levels) and a more extensive distribution of 131I within the nodules of the multinodular goitre. A more intense radiation effect was reflected in there being a higher output of serum Tg and thyroid hormones (group 2). As a consequence this group had a significantly higher reduction of the goitre volume. Also incidence of hypothyroidism post-RAI was significantly higher in group 2. We concluded that pretreatment with rhTSH in elderly patients with large multinodular goitres increases the uptake of the RAI therapeutic dose, thereby significantly reducing the multinodular goitre volume and relieving the compressive symptoms with relatively few side-effects.

Evolution of 131I from freshwater and its partitioning in simple aquatic microcosms

Our investigation quantifies iodine evolution from freshwater to the atmosphere. A factorial experimental design was employed in which the distribution of 131I was determined after 7 days in microcosms containing either (1) water (untreated Winnipeg River water), (2) Chlorella in a nutrient solution, (3) water and sediment (aerobic), or (4) water, sediment and N 2 gas (anaerobic). The 131I released from the microcosms to the atmosphere was retained by triethylenediamine (TEDA) impregnated charcoal traps. Evolution accounted for < 0.5% of the total 131I inventory and was in the order Chlorella > water > water and sediment > water, sediment and N 2 gas. Combining all treatments, the evolution coefficient had a geometric mean (G.M.) of 4.5 × 10 −5 day −1 with a geometric standard deviation (G.S.D.) of 3.7. In the water treatment, 97% of the 131I remained in solution, whereas 22% was algal-bound in the Chlorella treatment, and 80% and 7% were sediment-bound under aerobic and anaerobic conditions, respectively. A partition coefficient ( K d) value of 163 l · kg −1 dry weight (dry wt.) was obtained for the aerobic organic sediment, whereas a value of 3 l · kg −1 dry wt. was obtained for the anaerobic microcosms. On the basis of our K d values, the water to sediment transfer rate for iodine in Canadian Shield lakes would have a G.M. of 0.002 day −1 and G.S.D. of 7.8. We conclude that evolution of iodine generally constitutes only a minor component of losses from freshwater. Under aerobic conditions iodine is lost to the sediments, but under low oxygen conditions most of it remains in solution.

Study on the environmental behavior of chernobyl-derived radionuclides in Kyushu Island, Japan

The environmental behavior of Chernobyl-derived radionuclides in Kyushu Island was investigated for one month after the accident. The radioactivity level in airborne dusts was two orders of magnitude lower than that observed in Western Europe. The distribution of 131I in airborne dusts shifted to a larger particle size compared with other radionuclides. The radionuclide concentration in seaweeds varied depending on the geographical situation where the sampling was done. The biological half-lives in red algae were calculated to be 17.4 d and 32.9 d for 131I and 103Ru, respectively. The concentration factors in red algae were estimated to be 3 × 10 3 and 5 × 10 3 for 131I and 103Ru, respectively. The cooking effect of 131I in seaweeds and the committed effective dose equivalent through ingestion of seaweed were also evaluated.

Tissue distribution of 131I radiolabeled transferrin in the athymic nude mouse: Localization of a human colon adenocarcinoma HT-29 xenograft

The tissue distribution of 131I-transferrin ( 131I-Tf) was studied in athymic nude mice having s.c. human colonic adenocarcinoma HT-29 xenografts. Four days after 131I-Tf injection, the 131I specific activity measured in the HT-29 tumor, i.e. amount of radioactivity per gram of fresh tissue, represented 0.31 ± 0.09% of the injected radioactivity and was 1.90 fold more than that measured in the murine colon ( P < 0.05). After correction for intravascular 131I-Tf as estimated by means of 99mTc-Sn in vivo labeling of red blood cells, the 131I specific activity observed in the HT-29 tumor was 7.21 fold more than that observed in the murine colon. This subtracting method enabled us to localize a HT-29 tumor xenograft by γ scintigraphy of the entire animal and demonstrated that 131I-Tf could be a non-specific but potent marker for human colon cancer.

Radioiodine in kelp from western Australia

As part of a program to surley low levels of radioactivity in the marine environment of the southern hemisphere, we have studied the distribution and uptake of131I found in the subtidal kelp Ecklonia radiata, on the west coast of Australia. Concentrations of 5 to 75 fCi/g of131I exist in this species over a considerable distance along the coast. We have characterized the principal source of the131I and found a general temporal correlation between the amount of radioiodine discharged from sewer outfalls and its concentration in kelp. Transplant experiments have enabled us to estimate uptake and depuration rates, and our results are consistent with laboratory measurements made by others.

The significance of extrathyroidal radioactive iodine accumulation and secretion in clinical pathology.

The uptake and the distribution of 131I- injected intravenously into rats was followed up by whole body autoradiography. Extrathyroidal accumulations with some interest for clinical pathology were found in the nose, the hair follicles and the mucous cells of the stomach.