Iodine deficiency, radiation dose, and the risk of thyroid cancer among children and adolescents in the Bryansk region of Russia following the Chernobyl power station accident. (65/256)

BACKGROUND: Little is known about the joint effect of iodine deficiency and radiation exposure on the risk of thyroid cancer. No epidemiological studies have been published assessing the modifying effect of iodine deficiency on radiation-induced thyroid cancer following the Chernobyl accident. METHODS: A population sample of 3070 individuals (2590 ages 6-18, and 480 adults) from 75 settlements in the most highly contaminated regions of the Bryansk Oblast of Russia was identified and sampled for urinary iodine measurements in 1996, and iodine deficiency in each geopolitical unit (raion) was estimated. All cases of thyroid cancer were identified in those born 1968-1986 who were resident in the study area in May-June 1986 (34 histologically confirmed cases). The risk of thyroid cancer was examined in relation to population estimates of thyroid radiation dose and urinary iodine excretion level. RESULTS: The excess relative risk (ERR) of thyroid cancer was significantly associated with increasing thyroid radiation dose, and was inversely associated with urinary iodine excretion levels. There was a joint effect of radiation exposure and iodine deficiency. At 1 gray (Gy), the ERR in territories with severe iodine deficiency was approximately two times that in areas of normal iodine intake. CONCLUSIONS: These findings suggest that elimination of iodine deficiency in areas affected by Chernobyl may be important in reducing the effects of radiation exposure on the thyroid. If confirmed by studies based on individuals, they may have implications for the use of stable iodine in the case of population exposure to radioactive iodine.  (+info)

Single administration of stem cell factor, FLT-3 ligand, megakaryocyte growth and development factor, and interleukin-3 in combination soon after irradiation prevents nonhuman primates from myelosuppression: long-term follow-up of hematopoiesis. (66/256)

Preservation of hematopoietic stem and progenitor cell survival is required for recovery from radiation-induced myelosuppression. We recently showed that short-term injection of antiapoptotic cytokine combinations into mice soon after lethal gamma irradiation promoted survival. The present study investigated the hematopoietic response of cynomolgus monkeys to a single dose of stem cell factor, FLT-3 ligand, megakaryocyte growth and development factor, and interleukin-3 in combination (4F, each factor given intravenously at 50 microg/kg) administered 2 hours after 5-Gy gamma irradiation. Treated monkeys (n = 4) experienced no thrombocytopenia. Only 1 in 4 displayed a transient period of neutropenia (neutrophil [ANC] count < 0.5 x 10(9)/L), whereas all irradiated controls (n = 4) experienced neutropenia (5-12 days) and thrombocytopenia (platelet [PLT] count < 20 x 10(9)/L, 5-31 days). Treated animals exhibited an impressive 2-wave PLT response that peaked at days 8 and 22 after total body irradiation (TBI). Areas under the curve (AUC) of PLTs, ANCs, white blood cells (WBCs), and red blood cells (RBCs) between days 0 and 90 were significantly higher in treated animals than in controls. Humeral bone marrow-derived clonogenic activity was significantly spared at 24 hours and 4 days after TBI in treated monkeys. No apparent impairment of the hematopoietic status and stem cell pool, in terms of long-term culture-initiating cells (LTC-ICs) and side population (SP) cells, was observed after 15 months. These results strongly suggest that the 4F cytokine combination, as a single dose regimen, could act as an emergency treatment for nuclear accident or terrorism victims.  (+info)

Objectivity and ethics in environmental health science. (67/256)

During the past several decades, philosophers of science and scientists themselves have become increasingly aware of the complex ways in which scientific knowledge is shaped by its social context. This awareness has called into question traditional notions of objectivity. Working scientists need an understanding of their own practice that avoids the naive myth that science can become objective by avoiding social influences as well as the reductionist view that its content is determined simply by economic interests. A nuanced perspective on this process can improve research ethics and increase the capacity of science to contribute to equitable public policy, especially in areas such as environmental and occupational health, which have direct implications for profits, regulation, legal responsibility, and social justice. I discuss research into health effects of the 1979 accident at Three Mile Island near Harrisburg, Pennsylvania, USA, as an example of how scientific explanations are shaped by social concepts, norms, and preconceptions. I describe how a scientific practice that developed under the influence of medical and nuclear physics interacted with observations made by exposed community members to affect research questions, the interpretation of evidence, inferences about biological mechanisms in disease causation, and the use of evidence in litigation. By considering the history and philosophy of their disciplines, practicing researchers can increase the rigor, objectivity, and social responsibility of environmental health science.  (+info)

Urinary iodine kinetics after oral loading of potassium iodine. (68/256)

We studied the kinetics of iodine in various forms, in order to establish appropriate guidelines of iodine prophylaxis for thyroid blockade at nuclear emergency in "iodine rich areas", such as Japan. First, the effect of equivalent dose of potassium iodide (KI) (solution vs. tablet) was evaluated with excretions of urinary iodine (UI) at Nagasaki, Japan, and it was revealed that there was no difference of iodine kinetics between solution and tablet. We also performed the same study at Gomel, Belarus, which was known to be an iodine deficient area, and obtained the same results. Second, the kinetics of iodine included in "iodine rich" food was also evaluated with excretions of UI. Interestingly, the ratio of UI excretion with iodine rich food was significantly lower than that with KI tablets until 6 h after the intake (ANOVA, p = 0.02). These results proved that 1) KI solution as well as its tablet is useful for prophylaxis and 2) prophylaxis by iodine rich food is not effective for rapid blockade of thyroid gland at nuclear emergency. Finally, we emphasized that the approach from social medicine is definitely important to establish an effective iodine prophylaxis.  (+info)

137Cs soil-to-plant transfer for individual species in a semi-natural grassland. Influence of potassium soil content. (69/256)

In the present study we assessed the radiocaesium uptake by plants in order to piece together information on factors affecting the uptake processes, particularly K supply and plant species differences. Vegetation uptake from soil contaminated by the Chernobyl accident was compared at two semi-natural grasslands. The Cs/K discrimination factor (DF), which is often used to evaluate a plant's efficiency in absorbing nutrients from soil, was estimated. The obtained DF values (0.01 to 0.8) vary with K soil concentrations and plant species, indicating that the (40)K is more efficiently absorbed than (137)Cs. The soil-to-plant relationship was evaluated by means of the transfer factor (TF). The (137)Cs TF(sp) values obtained from separated plant species varied within the range of 0.016 to 0.400 (site 1) and 0.017 to 0.171 (site 2). When mixed grass samples were considered a large variation was observed, mainly for site 1. The (137)Cs TF(mix) ranges were: 0.018 to 0.250 for site 1 and 0.017 to 0.167 for site 2. These values fall within the range of TFs commonly reported (0.0001-1). Our present data suggest that these pastures are apt for forage use. Different plant species presented different individual behavior regarding their (137)Cs TF(sp) when the (40)K soil activity concentration was taken in account. For most of the species analyzed, we observed a gradual decrease in the individual (137)Cs TF(sp) when the (40)K soil activity concentration was increased, with the exception of Taraxacum officinale at one of the sampling sites.  (+info)

Monitoring of radiation-induced germline mutation in humans. (70/256)

Estimating the genetic hazards of radiation and other mutagens in humans depends on extrapolation from experimental systems. Recent data have shown that minisatellite loci provide a useful and sensitive experimental approach for monitoring radiation-induced mutation in humans. This review describes the progress made in validating this approach and presents the results of recent publications on the analysis of minisatellite mutation rates in the irradiated families.  (+info)

Chronic Cs-137 incorporation in children's organs. (71/256)

In Belarus's Gomel region, which was heavily contaminated by fallout from the Chernobyl disaster, we have studied the evolution of the Cs-137 load in the organisms of the rural population, in particular children, since 1990. Children have a higher average burden of Cs-137 compared with that of adults living in the same community. We measured the Cs-137 levels in organs examined at autopsy. The highest accumulation of Cs-137 was found in the endocrine glands, in particular the thyroid, the adrenals and the pancreas. High levels were also found in the heart, the thymus and the spleen.  (+info)

Radiation disaster response: preparation and simulation experience at an academic medical center. (72/256)

OBJECTIVES: A mass casualty disaster drill involving the simulated explosion of a radiation dispersal device (dirty bomb) was performed with the participation of multiple hospitals, emergency responders, and governmental agencies. The exercise was designed to stress trauma service capacities, communications, safety, and logistic functions. We report our experience and critique of the planning, training, and execution of the exercise, with special attention to the integrated response of the Departments of Nuclear Medicine, Health Physics, and Emergency Medicine. METHODS: The Health Physics Department presented multiple training sessions to the Emergency Medicine Department, Operating Room, and ancillary staff; reviewing basics of radiation biology and risk, protection standards, and detection of radiocontamination. Competency-based simulations using Geiger-Muller detectors and sealed sources were performed. Two nuclear medicine technologists played an important role in radiation discrimination-that is, assessment of radioactive contamination with survey meters and radionuclide identification based on gamma-spectroscopy of wipe smears from patients' clothing, skin, and orifices. Three Health Physics personnel and one senior Nuclear Medicine staff member were designated the radiation control officers for assigned teams triaging or treating patients. Patients were triaged and, when indicated, decontaminated. RESULTS: Within a 2-h period, 21 simulated victims arrived at our institution's Emergency Room. Of these, 11 were randomized as noncontaminated, with 10 as contaminated. Decontamination procedures were implemented in a hazardous materials (HAZMAT) decontamination trailer and, for the 5 patients with simulated serious injuries, in a designated trauma room. A full debriefing took place at the conclusion of the exercise. Staff largely complied with appropriate radiation protection protocols, although decontamination areas were not effectively controlled. The encountered limitations included significant lapses in communications and logistics, lack of coordination in the flow of patients through the HAZMAT trailer, insufficient staff to treat acute patients in a radiation control area, additional personnel needed for transport, and insufficient radiation safety personnel to control each decontamination room. CONCLUSION: Nuclear Medicine personnel are particularly well qualified to assist Health Physics and Emergency Medicine personnel in the preparation for, and management of, mass casualty radiation emergencies. Simulation exercises, though resource intensive, are essential to an institution's determination of response capability, performance, and coordination with outside agencies.  (+info)