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PubMed2006

A novel technique for the rapid identification of alpha emitters released during a radiological incident.

Before the May 2003 TOPOFF II exercise in Seattle, the U.S. EPA's Laboratory in Las Vegas prepared five spiked samples to be analyzed by the Washington State Department of Health's (WSDOH) Radiation Laboratory. Two of these were simulated deposition samples prepared on packaging tape. Laboratories throughout the world are investigating rapid methods for analyzing plume-borne radioactive materials. While measuring gamma emitters in environmental samples is fairly straightforward, the potential presence of alpha emitters adds complexity. The short range of alpha particles and the high degree of energy interference between nuclides usually require chemical separations and very thin mounts for alpha spectrometry. Work published on Frisch-Grid alpha counting of transuranics in soil and the commercial development of radon-rejection for air filters indicate that alpha spectrometry can be used directly on some media with success. This suggests that plume-borne material sampled from air or freshly deposited surface layers may be counted directly by alpha spectrometry, making it possible to identify both alpha and gamma emitters and determine their relative concentrations. The long-range objective is to propose a sampling method that can be used for rapid qualitative and semi-quantitative analyses using conventional radioanalytical instruments, with minimal preparation. This paper describes experimentation with this approach during a real-time exercise. All samples were prepared by spiking with (137)Cs, (241)Am, (238)Pu, and (239)Pu and presented to the WSDOH's Radiation Laboratory for analysis during TOPOFF II. The laboratory quickly identified and determined the ratios of all four contaminants on the tape samples using sequential alpha spectrometry and gamma-ray spectroscopy without chemical separations.

Air Pollutants, Radioactive↗
PubMed2001

Albinism and phenotype of barn swallows (Hirundo rustica) from Chernobyl.

The effects of mutation on phenotypic expression are supposed to be mainly deleterious because mutations disrupt the expression of genes that function relatively well under current environmental conditions. Thus, mutations are assumed to give rise to deviant phenotypes that are generally selected against. Radioactive contamination in the Chernobyl region of Ukraine is associated with a significant increase by a factor two to 10 in mutation rate in microsatellite markers of the barn swallow, Hirundo rustica. Barn swallows from Chernobyl had a temporally constant, elevated frequency of partial albinism compared to the situation before radioactive contamination and compared to birds from a control area. Albinism disproportionately affected the carotenoid-based plumage of the head, suggesting that carotenoid metabolism is particularly susceptible to the effects of radiation. Individuals with partially albinistic plumage had, on average, lower mean phenotypic values than other birds, and this was particularly the case for males. Furthermore, differences in phenotypic variation, as determined using Levene's test, were significantly larger in partial albinos compared to nonalbinos in males, but not in females, even though the null expectation would be the opposite due to the lower mean phenotypic values of partial albinos. Although small phenotypes were commonly associated with germline mutations, there was no general decrease in overall body size during the period 1991-2000, implying that small individuals were selected against. Because partial albinism is disfavored by natural selection, the effects of mutations are deleterious, giving rise to a balance between mutation and selection.

Albinism↗
PubMed2004

Caries prevalence, oral health behavior, and attitudes in children residing in radiation-contaminated and -noncontaminated towns in Ukraine.

INTRODUCTION: Several studies investigating the oral health status of children living in Ukraine after the Chernobyl catastrophe revealed an increase of caries in children residing in radionucleotide-contaminated areas. PURPOSE: (1) To compare prevalence of dental caries in contaminated and noncontaminated towns; and (2) to determine if there is a difference between dental behaviors and attitudes of children residing in contaminated and noncontaminated areas that may have contributed to differences in caries prevalence. METHODS: Children aged 13-14 were randomly selected in two towns of approximately the same population size (33 000): Ovruch (n = 119) from a contaminated area and Mirgorod (n = 100) from a noncontaminated area. Data on behaviors and attitudes were collected via a self-administered questionnaire having six domains: (i) family background; (ii) dental anxiety; (iii) dental utilization; (iv) oral hygiene; (v) use of fluoride toothpaste; and (vi) sugar consumption. Oral examinations included information on carious lesions, restorations, missing teeth, and soft tissue abnormalities. Caries prevalence was compared using a t-test. Regression analysis was conducted to determine the independent contribution of oral hygiene behaviors and dental utilization. RESULTS: There was a significant difference in caries prevalence in the contaminated town (mean DMFT = 9.1 +/- 3.5) versus the noncontaminated town (mean DMFT = 5.7 +/- 1.4; P < 0.000). Oral hygiene practices, age, and utilization of dental services were not found to be associated with differences in DMFT score between the two communities. CONCLUSION: There was a significantly higher caries prevalence in a radiation-contaminated town compared to a noncontaminated town of Ukraine. The difference was not explained by differences in oral health knowledge, attitudes or behaviors.

Adolescent↗
PubMed1996

Thyroid ultrasound findings 7 years after the Chernobyl accident. A comparative epidemiological study in the Bryansk region of Russia.

AIMS: The accident at the Chernobyl nuclear power station occurred in April 1986. We report on a comparative epidemiological study on thyroid abnormalities in the contaminated and uncontaminated populations of the Bryansk region, South-West Russia, in 1993, 7 years after the accident. MATERIAL AND METHODS: The study material consisted of all inhabitants aged 3-34 years in the contaminated village of Mirnyi and in the uncontaminated village of Krasnyi Rog, excluding those who had moved to the villages after the accident. The total material comprised 302 inhabitants in Mirnyi and 200 in Krasnyi Rog. RESULTS: No pathological US findings in either village were found in children born after the accident. In the age group 0-9 years old at the time of the accident, the prevalence of thyroid abnormalities was 8.1% in the contaminated village compared to 1.6% in the uncontaminated village. In the age group 10-27 years the corresponding figures were 18.8% and 17.7%. Only 55% of the pathological US findings were detected by physical palpation. CONCLUSION: The total prevalence of thyroid abnormalities was higher among children in the contaminated village. We recommend an active screening of young contaminated subjects with US, supplemented with fine needle biopsy.

Adolescent↗
PubMed2004

Experimental system to displace radioisotopes from upper to deeper soil layers: chemical research.

BACKGROUND: Radioisotopes are introduced into the environment following nuclear power plant accidents or nuclear weapons tests. The immobility of these radioactive elements in uppermost soil layers represents a problem for human health, since they can easily be incorporated in the food chain. Preventing their assimilation by plants may be a first step towards the total recovery of contaminated areas. METHODS: The possibility of displacing radionuclides from the most superficial soil layers and their subsequent stabilisation at lower levels were investigated in laboratory trials. An experimental system reproducing the environmental conditions of contaminated areas was designed in plastic columns. A radiopolluted soil sample was treated with solutions containing ions normally used in fertilisation (NO3-, NH4+, PO4--- and K+). RESULTS: Contaminated soils treated with an acid solution of ions NO3-, PO4--- and K+, undergo a reduction of radioactivity up to 35%, after a series of washes which simulate one year's rainfall. The capacity of the deepest soil layers to immobilize the radionuclides percolated from the superficial layers was also confirmed. CONCLUSION: The migration of radionuclides towards deeper soil layers, following chemical treatments, and their subsequent stabilization reduces bioavailability in the uppermost soil horizon, preventing at the same time their transfer into the water-bearing stratum.

Accidents↗
PubMed2003

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

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.

Cesium Radioisotopes↗
PubMed2006

Unstable-type chromosome aberrations in lymphocytes from individuals living near Semipalatinsk nuclear test site.

The Semipalatinsk nuclear test site area is considered to have been highly contaminated with radioactive fallout during 40 years of continuous nuclear testing. Individuals living near the nuclear test site are considered to have been exposed to both internal and external radiation. In order to assess the effects of prolonged radiation, a chromosome analysis was performed in lymphocytes from 123 people living in three villages, Dolon, Sarjar and Kaynar, and 46 control people in Kokpekty. A micronucleus assay was also conducted in 233 people in six different contaminated villages and one control village. Frequencies of dicentric and ring chromosomes were higher in residents of the contaminated area (1.55-2.56 per 1,000 cells) than those of the non-contaminated area (0.78 per 1,000 cells). Frequencies of dicentric chromosomes with fragments were also higher in the exposed group (0.44-0.96 per 1,000 cells). Among residents of the four villages, the incidence of multiple complex chromosome aberrations (MCA) was 0.03-0.34%. Incidences of micronucleus were also higher in the exposed group (9.36-12.3 per 1,000 lymphocytes) than the non-exposed group (7.25 per 1,000 lymphocytes). The higher incidence of unstable-type aberrations such as dicentric, ring chromosomes and micronuclei found in residents of contaminated areas seems to be mainly caused by internal exposure and other factors.

Adult↗
PubMed2006

Considerations regarding the implementation of EPR dosimetry for the population in the vicinity of Semipalatinsk nuclear test site based on experience from other radiation accidents.

General aspects of applying the method of retrospective dose estimation by electron paramagnetic resonance spectroscopy of human tooth enamel (EPR dosimetry) to the population residing in the vicinity of the Semipalatinsk nuclear test site are analyzed and summarized. The analysis is based on the results obtained during 20 years of investigations conducted in the Medical Radiological Research Center regarding the development and practical application of this method for wide-scale dosimetrical investigation of populations exposed to radiation after the Chernobyl accident and other radiation accidents.

Adult↗
PubMed1995

Ionizing radiation: future etiologic research and preventive strategies.

Estimates of cancer risks following exposure to ionizing radiation traditionally have been based on the experience of populations exposed to substantial (and known) doses delivered over short periods of time. Examples include survivors of the atomic bombings at Hiroshima and Nagasaki, and persons treated with radiation for benign or malignant disease. Continued follow-up of these populations is important to determine the long-term effects of exposure in childhood, to characterize temporal patterns of excess risk for different types of cancer, and to understand better the interactions between radiation and other host and environmental factors. Most population exposure to radiation occurs at very low dose rates. For low linear energy transfer (LET) radiations, it often has been assumed that cancer risks per unit dose are lower following protracted exposure than following acute exposure. Studies of nuclear workers chronically exposed over a working lifetime provide data that can be used to test this hypothesis, and preliminary indications are that the risks per unit dose for most cancers other than leukemia are similar to those for acute exposure. However, these results are subject to considerable uncertainty, and further information on this question is needed. Residential radon is the major source of population exposure to high-LET radiation. Current estimates of the risk of lung cancer due to residential exposure to radon and radon daughters are based on the experience of miners exposed to much higher concentrations. Data indicate that lung cancer risk among miners is inversely associated with exposure rate, and also is influenced by the presence of other lung carcinogens such as arsenic in the mine environment. Further study of populations of radon-exposed miners would be informative, particularly those exposed at below-average levels. More direct evidence on the effects of residential exposure to radon also is desirable but might be difficult to come by, as risks associated with radon levels found in most homes might be too low to be quantified accurately in epidemiological studies.

Adult↗
PubMed2004

Risk of thyroid cancer in the Bryansk Oblast of the Russian Federation after the Chernobyl Power Station accident.

This population-based case-control study investigated whether exposure to radiation from the Chernobyl Power Station accident is associated with an increased risk of thyroid cancer in children and adolescents aged 0-19 years at the time of the accident who were residing in the more highly contaminated areas of the Bryansk Oblast. Cases were diagnosed with thyroid cancer before October 1, 1997 (n = 26); two controls per case were identified from the Russian State Medical Dosimetrical Registry and were matched by gender, birth year, and raion of residence and type of settlement (urban, town, rural) on April 26, 1986 (n = 52). Individual radiation doses to the thyroid were estimated using a semi-empirical model and data were collected in interviews, primarily of the participants' mothers. Based on a loglinear dose-response model treating estimated dose as a continuous variable, the trend of increasing risk with increasing dose was statistically significant (one-sided P = 0.009). These data suggest that exposure to radiation from Chernobyl is associated with an increased risk of thyroid cancer, and that the relationship is dependent on dose. These findings are consistent with descriptive reports from contaminated areas of Ukraine and Belarus, and the quantitative estimate of thyroid cancer risk is generally consistent with estimates from other radiation-exposed populations.

Adolescent↗