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PubMed2003

Health effects of the Chernobyl accident: fears, rumours and the truth.

The impact of the world's worst nuclear disaster at Chernobyl in 1986 is reviewed within a framework of a triad of fear, rumour and truth. The scope of the accident, Soviet secrecy about it, and the lack of general awareness of, or disregard for, the effects of radiation created a fertile ground for persistent fears and rumours attributing any health problem to Chernobyl. Scientifically correct answers to health issues have been the means to combat disinformation, and to replace interconnected fears, misconceptions and rumours. To date, according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000 Report, based on a review of epidemiological and radiobiological studies, the main radiation-related effect of the Chernobyl accident is an increased risk of childhood thyroid cancer. In addition, the accident has had serious non-radiation-related psychological consequences on the residents of the contaminated territories, resettled populations and clean-up workers. Researchers in search of the truth through epidemiological reasoning are facing serious challenges which are reviewed within this article.

Child↗
PubMed2000

Measurement of technetium-99 in Marshall Islands soil samples by ICP-MS

Extraction techniques for recovery of technetium-99 (99Tc) for Inductively Coupled Plasma Mass Spectrometry (ICP-MS) measurements were evaluated using soil samples collected from the Marshall Islands. The results of three different extraction techniques were compared: (MI) acid leaching of Tc from ashed soil; (M2) acid leaching of Tc from raw dry soil; and (M3) Tc volatilization from ashed soil using a combustion apparatus. Total Tc recoveries varied considerably between the extraction techniques but each method yielded similar analytical results for 99Tc. Applications of these extraction techniques to a series of environmental samples and ICP-MS measurements have yielded first data on the 99Tc content of Marshall Islands soil samples contaminated with close-in radioactive fallout from nuclear weapons testing. The 99Tc activity concentration in the soil samples ranged between 0.1 and 1.1 mBq g(-1) dry weight (dw). The limit of detection for 99Tc by ICP-MS was 0.17 mBq per sample or 0.014 mBq g(-1) dw under standard operating conditions.

Journal Article↗
PubMedDate not supplied

129I and 36Cl concentrations in lichens collected in 1990 from three regions around Chernobyl.

129I and 36Cl were measured by accelerator mass spectrometry in 11 lichen samples (Parmelia sulcata) collected in 1990 from three regions (Novozybkov, Bragin and Ovruc) near Chernobyl. Previously measured activities of 137Cs were highest in the samples from the Novozybkov region while the measured activities of 36Cl and 129I in this study were highest in the samples from the Bragin region. The regional distribution patterns of the 36Cl and 129I show a positive correlation suggesting that these volatile radionuclides were deposited in the same manner.

Chlorine↗
PubMed1999

Distribution pattern of 90Sr and 137Cs in the Nile delta and the adjacent regions after Chernobyl accident.

Strontium and cesium contents in surface soil samples across the Nile Delta and the north coast of Egypt after the Chernobyl accident have been investigated. The concentration of 137Cs and 90Sr was determined using a high resolution gamma spectrometer based on hyperpure germanium detector (HPGe) and a liquid scintillation counter (LSC) respectively. 90Sr was determined through its decay product 90Y using Cerenkov counting. The determination of 90Sr was based on tributylphosphate (TBP) extraction of yttrium from nitric acid extract of ashed samples. The radioactivity of soils ranged between 18.5 and 2175 Bq/m2 with a mean of 652 Bq/m2 and 234 and 3129 Bq/m2 with a mean of 760 Bq/m2 for 137Cs and 90Sr respectively. An estimated absorbed dose equivalent due to the measured deposit of 137Cs was found to be 0.062 murem/h.

Cesium Radioisotopes↗
PubMed2000

The distribution of 137Cs and 90Sr in the biomass of pine trees planted in 1987-1988 in the near zone of the Chernobyl nuclear power plant.

This paper presents the results of a study, carried out in 1996, of the distributions of 137Cs and 90Sr in the biomass of a new pine plantation, planted in 1987-1988, in the near field of the Chernobyl nuclear power plant. The maximum observed concentrations were 4.2 MBq kg(-1) for 137Cs in the youngest needles and 1.1 MBq kg(-1) for 90Sr in the oldest needles. The estimation of the total absorbed doses in the different organs of the pine was also carried out, the observed doses were in the range 2 Gy yr(-1) to 16.8 Gy yr(-1); the lifetime dose for the needles (4 yr) was 44 Gy.

Biomass↗
PubMed2000

Retrospective dosimetry: estimation of the dose to quartz using the single-aliquot regenerative-dose protocol.

We report on the application of the single-aliquot regenerative-dose protocol to retrospective dosimetry, using the optically stimulated luminescence (OSL) from quartz extracted from fired bricks. These bricks had previously been exposed to enhanced levels of ionising radiation while part of inhabited structures in the Chernobyl area. The time dependence of the OSL signals is considered first and we conclude that it is most appropriate to use the initial part of the OSL signal for dose estimation, after subtraction of a slowly varying background component. It is then shown that this signal meets the fundamental requirement of the single-aliquot regenerative-dose protocol, in that any change in the luminescence recombination probability can be corrected for by using the OSL response to a fixed test dose. The response of a particular aliquot is examined after three different treatments (untreated, reset by exposure to light and reset by heating to 500 degrees C) and it is shown that, after sensitivity correction, the dose-response curves are indistinguishable up to 10 Gy. The routine application of the protocol is then described and dose estimates are shown to be insensitive to preheat temperature and test-dose size. Finally, dose-depth profiles are presented for two bricks. These profiles demonstrate that the high precisions (approximately 1%) obtained using the regenerative-dose protocol are reflected in smooth dose-depth dependencies.

Construction Materials↗
PubMed1998

Isolation and analysis of UV and radio-resistant bacteria from Chernobyl.

The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively.

4-Nitroquinoline-1-oxide↗
PubMedDate not supplied

Evaluation of 137Cs activity in plant drugs and in some phytoderivatives from Chernobyl accident up to present (1986-1994).

The accident to the nuclear power plant of Chernobyl (in April 1986) caused a radioactive contamination in large areas of the majority of European countries. During the first transient time the fall-out phenomenon was the most important method of contamination, particularly from 131I whose relative isotopic abundance with respect to other released radionuclides was very high. Thereafter, 137Cs, owing to its long half-time and its large presence in environmental matrixes and so in the food chain, became the element on which the attention was to be focused. Plant drugs and their derivatives are, at present, of very large alimentary consumption among people. This can cause some problems to human health, so the authors have studied (from 1986 to 1994) the activity of 137Cs in a large number of drugs (about 5000) and in some industrial and home-made officinal products. Some suggestions on the Cs+,K+ ions competition in soil can also be derived.

Cesium Radioisotopes↗
PubMed2000

Nested case-control study of leukemia among a cohort of persons exposed to ionizing radiation from nuclear weapon tests in kazakhstan (1949-1963).

PURPOSE: A unique opportunity for epidemiological studies of cancer and other health effects of radiation exposures exists around the Semipalatinsk Nuclear Test Site in Kazakhstan. The present study is the first analysis of leukemia risk among the residents of downwind settlements exposed to radioactive fallout from atmospheric nuclear weapon tests (1949-1963) and followed up from 1960 to 1998.METHODS: Within the cohort of 10,000 exposed subjects a case-control study was nested, including 22 leukaemia cases (except chronic lymphoid leukemia) and 132 controls individually (1:6 ratio) matched by birth year and sex. Leukemia deaths were identified by death certificates and diagnoses were verified by hospital records. The individual dose including internal and external exposure assessment was estimated according to the residency and age at exposure. All odds ratios were adjusted for ethnicity (Russian or Kazakh) as an independent variable.RESULTS: The median dose of exposure for all subjects was 0.89 Sv ranging from 0.01 to 5.71 Sv. A nearly two-fold increased risk of leukemia was found (OR = 1.91; 95% CI = 0.38 to 9.67) for persons exposed to doses of >2.0 Sv as compared to those exposed to <0.5 Sv, but no increase in risk with the dose was found for those exposed to doses lower than 2 Sv. Detailed evaluation of dose-response showed an excess relative risk for leukemia of 10% per 1 Sv of additional exposure.CONCLUSIONS: Our findings suggest that there is an increased risk of leukemia among those exposed to >2 SV as compared to those exposed to <0.5 Sv, but this could have been a chance finding due to the small number of cases and low statistical power.

Journal Article↗
PubMed1999

Micronucleus frequency in Gomel (Belarus) children affected and not affected by thyroid cancer.

Cytogenetic monitoring was carried out on a group of children from Gomel (Belarus), one of the areas most severely affected by radioactive contamination following the accident at the Chernobyl nuclear power plant, in 1986. We performed the micronucleus test (MN) in binucleated lymphocytes of 42 children (mean age: 11+/-2.34 years), 16 of whom were affected by thyroid gland tumor. Thirty healthy children living in Pisa (mean age: 14.96+/-2.17 years) were enrolled in the study as controls. Thyroid tumor affected children living in Gomel showed a statistically significant increase in the frequency of micronucleated cells as compared with the healthy children from Pisa. Moreover, a significant correlation was found between MN frequency and both the presence of tumor and higher 137Cs contamination. In addition, higher 137Cs contamination was more frequently observed in tumor affected children. These results suggest that the increased MN frequency is attributable more to 137Cs contamination rather than to the presence of the tumor itself.

Adolescent↗
PubMed1999

Radiation hazard caused by the Chernobyl accident in inhabited areas of Ukraine can be monitored by transgenic plants.

The genetic impact of the 1986 accident at the Ukraine Chernobyl Nuclear Power Plant (NPP) on populations of living organisms has yet to be fully assessed. Monitoring of the genotoxicity of polluted soils is a key element in the disaster management program. We used Arabidopsis thaliana and Nicotiana tabacum plants transgenic for a reporter gene revealing homologous recombination to study the genetic effects of chronic low-dose radiation stemming from the soil in inhabited areas of Ukraine where contamination by the accident ranges from 1 to 40 Ci/km2. We noted a significant dose-dependent increase of homologous recombination in plants cultivated in the affected inhabited areas, proving the persistently high genotoxicity of the radioactively contaminated soils.

Arabidopsis↗
PubMed2002

Chernobyl-related ionising radiation exposure and cancer risk: an epidemiological review.

The Chernobyl nuclear accident on 26th April, 1986, led to a massive release of radionuclides into the environment. Although vast areas of Europe were affected by Chernobyl-related ionising radiation, the accident had the greatest impact in Belarus, Ukraine, and the Russian Federation. Epidemiological studies that have investigated the link between the Chernobyl accident and cancer have largely focused on malignant diseases in children, specifically thyroid cancer and leukaemia. There is good evidence to suggest that rates of thyroid cancer in children from the countries that were formally part of the Soviet Union have risen as a consequence of the Chernobyl accident. The findings for childhood leukaemia are less conclusive. Overall rates for this disease do not seem to have been affected by the Chernobyl-related ionising radiation, but there may be a larger risk of infant leukaemia in contaminated areas of Europe. Among adult populations, there is no strong evidence to suggest that risk of thyroid cancer, leukaemia, or other malignant disease has increased as a result of the Chernobyl accident.

Adult↗
PubMed2003

Reduction of crop contamination by soil resuspension within the 30-km zone of the Chernobyl nuclear power plant.

A field experiment was conducted within the 30-km zone of the Chernobyl Nuclear Power Plant to analyze whether the application of mulching reduced resuspension of 137Cs contaminated soil in oat (Avena sativa) crops. In 1993, we applied a mulch treatment at a dose of 200 g m(-2), and soil resuspension was measured by estimating soil loadings onto plant surfaces from Ti concentrations in plants. In 1994, two mulch doses were applied, 200 and 50 g m(-2), and we estimated the contribution of soil resuspension by using artificial resuspension collection devices (ARC). In the 1993 experiment between 4.6 and 34.4% of the plant's total 137Cs contamination was attributed to external soil contamination. The mean amount of soil-derived 137Cs attached to vegetation was 124.7 Bq kg(-1)(plant) in control plots and 53.7 Bq kg(-1)(plant) in mulched plots. In the 1994 experiment, covering the soil with a mulch layer decreased the radiocesium content in ARC by about 70%. Results obtained in these experiments suggest that soil resuspension was a significant mechanism for plant contamination and that mulching was effective in reducing that contamination.

Agriculture↗
PubMed2001

An ecological analysis of leukemia incidence around the highest 137Cs concentration in Poland.

Cancer has long been known to be a hazard of exposure to ionizing radiation. However, the assessment of health effects from exposure to radiation is a matter of considerable controversy. This paper presents results of a retrospective study of leukemia incidence (203-207, ICD-9) around the highest 137Cs pollution in Poland (as an effect of the Czarnobyl disaster and/or military bomb tests). The data relating to all the registered leukemias in males and females originated from the Regional Cancer Registry in Opole. The information on 137Cs concentration rates in Opole province was derived from the state monitoring provided by the Polish Geological Institute in Warsaw. The spatial analysis--based on the random-effects Poisson regression model--was carried out via the Markov Chain Monte Carlo (MCMC) technique (Gibbs sampling) using BUGS software. The model incorporated epidemiological data and an ecological covariate--isotope concentrations--and provided a framework for estimating the strength of a dose-response relationship. The differences in incidence levels were quantified by traditional standardized morbidity ratios (SMRs) and presented in thematic maps as well as in combined charts of distance-disease-dose relations. Additionally, to assess spatial disease clustering, a Tango test was adopted. The results of this ecological study suggest that the 137Cs concentrations did not have any negative influence on the exposed population.

Bayes Theorem↗