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Congenital anomalies of the central nervous system at autopsy in Croatia in the period before and after the Chernobyl accident.

In this study, we analyzed the frequency, type and sex distribution of congenital anomalies of the central nervous system (CNS) at autopsy in the period prior to and after the Chernobyl accident in northwest Croatia, one of the areas with the highest exposure to nuclear contamination from Chernobyl. All autopsies in both periods were performed by the same technique, i.e. dissection of the trunk and head, and inspection of the extremities. There were 53 infants with congenital anomalies of the CNS in the period prior to, and 99 in the period after the Chernobyl accident. Our results showed a statistically significant increase in the incidence of CNS anomalies in general (chi 2 = 4,719, p < 0.05, D. F. = 1) and of neural tube defects (chi 2 = 5.380, p < 0.05, D. F. = 1) in the period after the Chernobyl accident. Differences in the incidence of various CNS anomalies, in all types of anomalies, and in sex distribution were not statistically significant. Studies of the association between the Chernobyl accident and congenital anomalies showed no clear changes in the prevalence of anomalies at birth which might have been associated with the accident. This study provided some additional data on the frequency of CNS anomalies in the period after the Chernobyl accident in one of the areas with the highest exposure to the nuclear contamination from Chernobyl. We suggest that the frequency of all anomalies, including CNS, in the period after the Chernobyl accident should be carefully monitored.

Abnormalities, Radiation-Induced↗

Upregulation of fibroblast growth factor receptor 3 and epidermal growth factor receptors, in association with Raf-1, in urothelial dysplasia and carcinoma in situ after the Chernobyl accident.

The present study was carried out in order to examine the molecular status of selected growth factor receptors (GFR) in urinary bladder lesions, recently described by our group as representing 'Chernobyl cystitis'. Fibroblast growth factor receptor 3 (FGFR3), epidermal growth factor receptor 1 (EGFR1), EGFR2neu (a member of the same family), p53 and Raf-1 serine/threonine kinase expression were evaluated immunohistochemically in urinary bladder biopsies from 22 men with benign prostate hyperplasia (group 1). For comparison, 16 men with benign prostate hyperplasia and five women with chronic cystitis living in non-radio-contaminated areas of the country were also investigated as controls (group 2). Additionally, 14 patients with dysplasia, carcinoma in situ (CIS) and primary urothelial carcinoma (UC) operated before the Chernobyl accident as well as 23 patients with UC living in the radio-contaminated areas were included as pre- and post-Chernobyl UC groups 1 and 2, respectively. Chronic proliferative atypical cystitis ('Chernobyl cystitis') was observed in group 1 patients. Foci of dysplasia and CIS were found in 22 (100%) and 19 (86%) of the 22 cases, respectively; moreover, two small UC were also detected. Elevated levels of FGFR3, EGFR2/neu, p53 and to a lesser extent EGFR1 and Raf-1 expression in the urothelial dysplasia and CIS were evident for patients of group 1. Statistically significant differences in immunohistochemical scores for FGFR3, EGFR1, p53 and Raf-1 were observed between groups 1 and 2 and between group 1 and the post-Chernobyl UC group 2, where a change in expression of EGFR2/neu was also noted. A significant decrease in FGFR3 expression in additional pre-Chernobyl UC group 1 with dysplasia, CIS and UC compared with group 1 Chernobyl cystitis cases was detected. Our findings suggest that FGFR and EGFR signaling pathways, associated with p53 and Raf-1 activation, may contribute to multistage urothelial carcinogenesis caused by irradiation, through autocrine or paracrine growth stimulation.

Adult↗

Ecological half-time of radiocesium from Chernobyl debris and from nuclear weapons fallout as measured in a group of subjects from the south of Sweden.

From 1960 to 1980 and between 1987 and 1994 the whole-body content of 17Cs, and when possible also 134Cs, was measured in a group of subjects living in the city of Lund, Sweden (55.7 degrees N, 13.2 degrees E). The results have been analyzed to estimate the effective ecological half-time of fallout radiocesium in humans living in the area. The Lund area (The Province of Skåne) was subjected to a deposition of about 2 kBq m(-2) of pre-Chernobyl 137Cs from nuclear weapons testing and 1 kBq m(-2) of 137Cs from Chernobyl fallout in May 1986. The radiocesium from the nuclear weapons tests in the 1950's and 1960's still gave a significant contribution to the total 137Cs levels in humans in the post-Chernobyl study period (1987-1994) of about 0.4 Bq per kg body weight, which was about 10% of the peak post-Chernobyl concentration level of 137Cs (3.5-4 Bq kg(-1)) in 1987. The effective ecological half-time for 137Cs from Chernobyl was found to be 1.8 +/- 0.2 y. The aggregate transfer factor from deposition to mean activity concentration in man was estimated to be 3.6 Bq kg(-1)/kBq m(-2). These values may be compared with an effective ecological half-time of 1.3 y found in the reference group in the 1960's, and an aggregate transfer factor of 10 Bq kg(-1)/kBq m(-2). This difference is largely explained by the continuous nature of the global fallout leading to contamination on growing crops whereas the Chernobyl fallout occurred just prior to the South Swedish growing season, leading to less efficient transfer to crops and to human diet. The average committed individual effective dose (50 y) from ingested 137Cs from the Chernobyl fallout was estimated to be 0.02 mSv and from the nuclear weapons fallout (1945-1995) to be 0.20 mSv.

Adult↗

Chernobyl as a population sink for barn swallows: tracking dispersal using stable-isotope profiles.

Stable-isotope profiles of feathers can reveal the location or habitat used by individual birds during the molting period. Heterogeneity in isotope profiles will reflect heterogeneity in molt locations, but also heterogeneity in breeding locations, because spatial heterogeneity in molt locations will be congruent with spatial heterogeneity in breeding locations in species with high connectivity between breeding and molting sites. We used information on the congruence of spatial heterogeneity in molt and breeding location to study population processes in Barn Swallows (Hirundo rustica) from a region. near Chernobyl, Ukraine, that has been radioactively contaminated since 1986; from an uncontaminated control region near Kanev, Ukraine; and from a sample of pre-1986 museum specimens used to investigate patterns prior to the nuclear disaster at Chernobyl, from both regions. Previous studies have revealed severe reductions in Barn Swallow reproductive performance and adult survival in the Chernobyl region, implying that the population is a sink and unable to sustain itself. Female Barn Swallows are known to disperse farther from their natal site than males, implying that female stable-isotope profiles should tend to be more variable than profiles of males. However, if the Barn Swallows breeding at Chernobyl are not self-sustaining, we would expect males there also to originate from a larger area than males from the control region. We found evidence that the sample of adult Barn Swallows from the Chernobyl region was more isotopically heterogeneous than the control sample, as evidenced from a significant correlation between feather sigma13C and sigma15N values in the control region, but not in the Chernobyl region. Furthermore, we found a significant difference in feather sigma15N values between regions and periods (before and after 1986). When we compared the variances in sigma13C values of feathers, we found that variances in both sexes from post-1986 samples from Chernobyl were significantly larger than variances for feather samples from the control region, and than variances for historical samples from both regions. These findings suggest that stable-isotope measurements can provide information about population processes following environmental perturbations.

Aging↗

Estimates of the cancer burden in Europe from radioactive fallout from the Chernobyl accident.

The Chernobyl accident, which occurred April 26, 1986, resulted in a large release of radionuclides, which were deposited over a very wide area, particularly in Europe. Although an increased risk of thyroid cancer in exposed children has been clearly demonstrated in the most contaminated regions, the impact of the accident on the risk of other cancers as well as elsewhere in Europe is less clear. The objective of the present study was to evaluate the human cancer burden in Europe as a whole from radioactive fallout from the accident. Average country- and region-specific whole-body and thyroid doses from Chernobyl were estimated using new dosimetric models and radiological data. Numbers of cancer cases and deaths possibly attributable to radiation from Chernobyl were estimated, applying state-of-the-art risk models derived from studies of other irradiated populations. Simultaneously, trends in cancer incidence and mortality were examined over time and by dose level. The risk projections suggest that by now Chernobyl may have caused about 1,000 cases of thyroid cancer and 4,000 cases of other cancers in Europe, representing about 0.01% of all incident cancers since the accident. Models predict that by 2065 about 16,000 (95% UI 3,400-72,000) cases of thyroid cancer and 25,000 (95% UI 11,000-59,000) cases of other cancers may be expected due to radiation from the accident, whereas several hundred million cancer cases are expected from other causes. Although these estimates are subject to considerable uncertainty, they provide an indication of the order of magnitude of the possible impact of the Chernobyl accident. It is unlikely that the cancer burden from the largest radiological accident to date could be detected by monitoring national cancer statistics. Indeed, results of analyses of time trends in cancer incidence and mortality in Europe do not, at present, indicate any increase in cancer rates -- other than of thyroid cancer in the most contaminated regions -- that can be clearly attributed to radiation from the Chernobyl accident.

Adolescent↗

Iodine-129 in soils from Northern Ukraine and the retrospective dosimetry of the iodine-131 exposure after the Chernobyl accident.

Forty-eight soil profiles down to a depth of 40 cm were taken in Russia and Ukraine in 1995 and 1997, respectively, in order to investigate the feasibility of retrospective dosimetry of the 131I exposure after the Chernobyl accident via the long-lived 129I. The sampling sites covered areas almost not affected by fallout from the Chernobyl accident such as Moscow/Russia and the Zhitomir district in Ukraine as well as the highly contaminated Korosten and Narodici districts in Ukraine. 129I was analyzed by radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS). 127I was measured for some profiles by RNAA or ion chromatography (IC). The results for 127I demonstrated large differences in the capabilities of the soils to store iodine over long time spans. The depth profiles of 129I and of 137Cs showed large differences in the migration behavior between the two nuclides but also for each nuclide among the different sampling sites. Though it cannot be quantified how much 129I and 137Cs was lost out of the soil columns into deeper depths, the inventories in the columns were taken as proxies for the total inventories. For 129I, these inventories were at least three orders of magnitude higher than a pre-nuclear value of 0.084+/-0.017 mBq m(-2) derived from a soil profile taken in 1939 in Lutovinovo/Russia. From the samples from Moscow and Zhitomir, a pre-Chernobyl 129I inventory of (44+/-24) mBq m(-2) was determined, limiting the feasibility of 129I retrospective dosimetry to areas where the 129I inventories exceed 100 mBq m(-2). Higher average 129I inventories in the Korosten and Narodici districts of 130 and 848 mBq m(-2), respectively, allowed determination of the 129I fallout due to the Chernobyl accident. Based on the total 129I inventories and on literature data for the atomic ratio of 129I/131I=13.6+/-2.8 for the Chernobyl emissions and on aggregated dose coefficients for 131I, the thyroid exposure due to 131I after the Chernobyl accident was estimated for the inhabitants of four villages in the Korosten and of three villages in the Narodici districts. The limitations and uncertainties of the 129I retrospective dosimetry are discussed.

Chernobyl Nuclear Accident↗

Chromosomal imbalances in post-chernobyl thyroid tumors.

Tissue samples from 60 post-Chernobyl childhood thyroid tumors have been investigated. We used comparative genomic hybridization (CGH) to detect chromosomal gains and losses within the tumor DNA. This is the first CGH study on childhood thyroid tumors. The post-Chernobyl tumors showed chromosomal imbalances in 30% of tumors. The most frequent DNA copy number changes in post-Chernobyl tumors involved chromosomes 2, 7q11.2-21, 13q21-22, 21 (DNA gains), and chromosomes 16p/q, 20q, 22q (DNA losses). Some of these specific alterations detected in post-Chernobyl thyroid tumors (deletions on chromosomes 16p/q and 22q) have previously been reported in thyroid tumors as associated with an aggressive biologic behavior and may therefore also account for the more aggressive phenotype of papillary thyroid carcinoma (PTC) found in post- Chernobyl tumors. Eighteen percent of post-Chernobyl PTC that exhibit RET rearrangements also showed chromosomal imbalances indicating that either additional genetic events are involved in this subset of tumors, or that intratumoral genetic heterogeneity exists in these tumors, suggesting a oligoclonal pattern to tumor development.

Adolescent↗

Nucleotide variation in the p53 tumor-suppressor gene of voles from Chernobyl, Ukraine.

The 1986 Chernobyl disaster contaminated vast regions of Ukraine and Belarus with a variety of radioactive isotopes and heavy metals. While over 90% of the radioactive isotopes have decayed into stable compounds, radiation levels in contaminated areas are still extraordinarily high. In fact, some rodents living near the reactor have internal 134,137Cs concentrations approaching 80 000 Bq/g. Several recent genetic analyses of vertebrates have illustrated that mutation rates of organisms exposed to radiation from Chernobyl are higher than in control groups, but none have studied DNA sequences. Nucleotide sequences of rodent mitochondrial genes were originally reported to have been hypervariable, but those results were subsequently retracted. Herein, I report the results of a pilot study to determine the extent of nucleotide variation at the p53 gene in four species of rodents (voles) from Chernobyl and from control sites. I sequenced a 788 bp region (coding and non-coding) of p53 in 30 different mice comprising four different species of Microtus. Nucleotide variation at the population level was due to deletions and substitutions; both were limited to introns. There were no significant differences between the number of haplotypes in radioactive and control populations (p=0.60). Rare or private alleles might have arisen due to unique mutational pressures at Chernobyl. Alternatively, natural selection might have favored one allele over others (i.e., a selective sweep). Neither scenario is strongly supported by these data. Thus, no apparent genetic effects of the Chernobyl disaster on the p53 gene of resident voles were revealed; more extensive surveys will be necessary to determine if mutation rates are indeed elevated in mice from Chernobyl. However, two salient points emerge; the first involves the utility of introns as markers for mutations in coding regions and the second considers the relative merits of cloning in mutation detection studies.

Animals↗

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↗

The psychosocial aftermath of the Chernobyl disaster in an area of relatively low contamination.

INTRODUCTION: There has been relatively little attention paid to the mid- and long-term effects of large-scale disasters, particularly their effects on children and young people. At the present time, the impact of the Chernobyl catastrophe on the daily lives of the affected population may include one of strong psychological stress due to uncertainty about ultimate health outcomes. Persons in the Chernobyl region in specific areas of low contamination may be affected similarly. This investigation assesses radiation concerns and attitudes about health and government information, nine years after the disaster, in a group of adults and adolescents residing in a relatively uncontaminated village in the Chernobyl area. METHODS: Questionnaires were administered to 94 adults and 50 adolescents. Items assessed beliefs about extent of radiation exposure, health concerns regarding oneself and family members, past and current preoccupation about the disaster, and trust in the accuracy of government information about health effects. RESULTS: Considerable uncertainty was demonstrated in both adults and adolescents about the extent of their and their families exposure to radiation. Marked distrust of past and current government information about health effects was evident. A large proportion of subjects reported that they still thought frequently about the Chernobyl accident. They worried about health problems related to radiation exposure whenever they or their family members exhibited physical symptoms or complaints, and they urged family members to go to a medical clinic for evaluation to assess these symptoms. CONCLUSIONS: The extent of long-term concerns about the personal and family health effects of the Chernobyl disaster in this population residing in a relatively uncontaminated village is striking: the psychological impact on adolescents is considerable. The stress generated is maintained by the realistic uncertainty about the ultimate health consequences to the overall population as a result of radiation exposure and distrust in government information about contamination levels in this particular village. The level of stress and its effects on physical and mental health may increase over time if there is a rise in morbidity in the area. The continuing health needs of the extremely large population affected by the Chernobyl disaster need to be addressed.

Adolescent↗

Increased frequency of sister chromatid exchanges in lymphocytes of Chernobyl clean-up workers.

Sister chromatid exchanges (SCEs) were analysed in lymphocytes from 12 control persons and 33 Chernobyl clean-up workers. The group of Chernobyl clean-up workers consisted of civilians who were forced to go to Chernobyl to clean up environmental contamination caused by Chernobyl disaster. On average, they received 0.13 (range 0.04-0.249) Gy of external irradiation before returning to home. Cytogenetic analyses were performed 6-8 years after the irradiation. Standard cytogenetic techniques were used. Mean SCE frequency was 7.45 +/- 0.69 SCE/cell in controls and 10.30 +/- 0.31 SCE/cell in clean-up workers (p < 0.05). Analysis of variance showed that exposure to radiation explained 19.6%, occupational exposure to various chemical substances, 11.9%, coffee consumption, 8.3%, smoking, 4.2%, interaction between smoking and coffee consumption, 3.6%, and alcohol abuse, 3.4% of total variation in SCE frequency. Effects of all above confounding factors were significant (p < 0.05). In addition, increased frequencies of chromosome aberrations due to exposure at Chernobyl and alcohol consumption were observed. However, there was no correlation between external dose of irradiation and the frequency of chromosome aberrations. Thus, even 6-8 years after the irradiation, cytogenetic effects in lymphocytes of Chernobyl clean-up workers are still significant.

Adult↗

Childhood leukaemia incidence in Hungary, 1973-2002. Interpolation model for analysing the possible effects of the Chernobyl accident.

The incidence of childhood leukaemia in Hungary has yet to be reported, although data are available since the early 70s. The Hungarian data therefore cover the time before and after the Chernobyl nuclear accident (1986). The aim of this study was to assess the effects of the Chernobyl accident on childhood leukaemia incidence in Hungary. A population-based study was carried out using data of the National Paediatric Cancer Registry of Hungary from 1973 to 2002. The total number of cases was 2204. To test the effect of the Chernobyl accident the authors applied a new approach called 'Hypothesized Impact Period Interpolation'-model, which takes into account the increasing trend of childhood leukaemia incidence and the hypothesized exposure and latency times. The incidence of leukaemia in the age group 0-14 varied between 33.2 and 39.4 per million person-years along the observed 30 year period, and the incidence of childhood leukaemia showed a moderate increase of 0.71% annually (p = 0.0105). In the period of the hypothesized impact of the Chernobyl accident the incidence rate was elevated by 2.5% (95% CI: -8.1%; +14.3%), but this change was not statistically significant (p = 0.663). The age standardised incidence, the age distribution, the gender ratio, and the magnitude of increasing trend of childhood leukaemia incidence in Hungary were similar to other European countries. Applying the presented interpolation method the authors did not find a statistically significant increase in the leukaemia incidence in the period of the hypothesized impact of the Chernobyl accident.

Adolescent↗

Absence of a specific radiation signature in post-Chernobyl thyroid cancers.

Thyroid cancers have been the main medical consequence of the Chernobyl accident. On the basis of their pathological features and of the fact that a large proportion of them demonstrate RET-PTC translocations, these cancers are considered as similar to classical sporadic papillary carcinomas, although molecular alterations differ between both tumours. We analysed gene expression in post-Chernobyl cancers, sporadic papillary carcinomas and compared to autonomous adenomas used as controls. Unsupervised clustering of these data did not distinguish between the cancers, but separates both cancers from adenomas. No gene signature separating sporadic from post-Chernobyl PTC (chPTC) could be found using supervised and unsupervised classification methods although such a signature is demonstrated for cancers and adenomas. Furthermore, we demonstrate that pooled RNA from sporadic and chPTC are as strongly correlated as two independent sporadic PTC pools, one from Europe, one from the US involving patients not exposed to Chernobyl radiations. This result relies on cDNA and Affymetrix microarrays. Thus, platform-specific artifacts are controlled for. Our findings suggest the absence of a radiation fingerprint in the chPTC and support the concept that post-Chernobyl cancer data, for which the cancer-causing event and its date are known, are a unique source of information to study naturally occurring papillary carcinomas.

Adenoma↗

The chernobyl accident 20 years on: an assessment of the health consequences and the international response.

BACKGROUND: The Chernobyl accident in 1986 caused widespread radioactive contamination and enormous concern. Twenty years later, the World Health Organization and the International Atomic Energy Authority issued a generally reassuring statement about the consequences. Accurate assessment of the consequences is important to the current debate on nuclear power. OBJECTIVES: Our objectives in this study were to evaluate the health impact of the Chernobyl accident, assess the international response to the accident, and consider how to improve responses to future accidents. DISCUSSION: So far, radiation to the thyroid from radioisotopes of iodine has caused several thousand cases of thyroid cancer but very few deaths ; exposed children were most susceptible. The focus on thyroid cancer has diverted attention from possible nonthyroid effects, such as mini-satellite instability, which is potentially important. The international response to the accident was inadequate and uncoordinated, and has been unjustifiably reassuring. Accurate assessment of Chernobyl's future health effects is not currently possible in the light of dose uncertainties, current debates over radiation actions, and the lessons from the late consequences of atomic bomb exposure. CONCLUSIONS: Because of the uncertainties over the dose from and the consequences of the Chernobyl accident, it is essential that investigations of its effects should be broadened and supported for the long term. Because of the problems with the international response to Chernobyl, the United Nations should initiate an independent review of the actions and assignments of the agencies concerned, with recommendations for dealing with future international-scale accidents. These should involve independent scientists and ensure cooperation rather than rivalry.

Chernobyl Nuclear Accident↗

[Facial cleft birth rate in former East Germany before and after the reactor accident in Chernobyl].

Cleft lip palates (CLP) are caused by a variety of factors. Ionizing radiation is only one of these factors. The meltdown of the nuclear reactor at Chernobyl on April 26, 1986, and the subsequent radioactive fallout did not cause any acute radiation sickness in Germany. Nevertheless, in West Berlin a significant increase of trisomy-21 cases was reported in births 9 months after the Chernobyl reactor accident. In our study we analyzed the influence of the radioactive fallout after the Chernobyl disaster on the rate and regional distribution of CLP newborns in the former German Democratic Republic (GDR). In contrast to the Federal Republic of Germany an ongoing malformation register for CLP newborns had existed in the former GDR since 4 July 1967. Environmental data were collected from national and international environmental authorities and atomic energy agencies. Population statistics were taken from the statistical year-book of the former GDR. During a 10-year period from 1980 to 1989, the average number of CLP newborns in the GDR was 1.88 per 1,000 live births. A significant prevalence increase was recorded in 1983, 1987 und 1988. In comparison to the mean rate in the period from 1980 until 1986, 1987 demonstrated an increase of 9.4%. Regional prevalence increases were seen in the three northern districts of Schwerin, Rostock and Neubrandenburg, where the radioactivity measurements in general showed higher levels of the radionuclides caesium-137 und strontium-90 than in other districts. Owing to the comprehensive malformation register for CLP patients in the GDR, this is the first study for Germany, analyzing the CLP rate before and after the fallout in Chernobyl. The results support the allegation of the influence of radiation-induced increase of CLP newborns after the Chernobyl reactor accident.

Abnormalities, Radiation-Induced↗

Radiocesium in muscle tissue of reindeer and pike from northern Sweden before and after the Chernobyl accident. A retrospective study on tissue samples from the Swedish Environmental Specimen Bank.

After the Chernobyl accident in April 1986, considerable deposition of radionuclides occurred regionally in eastern, central and northwestern Sweden. Locally, the fallout of radiocesium exceeded the remainder from atmospheric nuclear weapons tests by several magnitudes. Since the end of the 1960s samples of organs from various plant and animal species, annually collected at different localities, have been preserved in the Swedish Environmental Specimen Bank (ESB). In this work samples from the ESB have been used for retrospective studies of radioactive pollution. The activities of Cs-134 and Cs-137 in muscle tissues from reindeer, Rangifer tarandus, and pike, Esox lucius, preserved in the ESB, were measured. The samples were collected annually; the reindeer at three localities in northern Sweden and the pike at one of them. In material collected prior to the Chernobyl accident, the levels of Cs-137 were 57-180 Bq/kg in reindeer and 14-24 Bq/kg in pike, fresh weight basis. These levels relate to earlier nuclear bomb tests. A significant decrease was found in pike during the pre-Chernobyl period (1971-86). In post-Chernobyl samples the burden of Cs-137 varied from amounts equal to the former levels in the northernmost locality and up to 80 times higher for the maximum values in the southernmost locality. The highest value recorded was 18,425 Bq/kg in reindeer. The geographic variations in reindeer from Chernobyl fallout were in accordance with the pattern of deposition estimated by aircraft surveys performed in May 1986. The ratio between 'new' and 'old' radiocesium burdens in pike, caught in 1987, approached the corresponding ratio for reindeer grazing in the precipitation area of the lake; 33 and 19, respectively.

Accidents↗

Chromosome aberrations in Norwegian reindeer following the Chernobyl accident.

Chromosome analyses were carried out on peripheral blood lymphocytes of semi-domestic reindeer in Norway which had been exposed to varying amounts of radiocesium emanating from the Chernobyl accident. The sampling was done in the period 1987-1990. The material included 192 reindeer, originating from four herds in central Norway, an area considerably affected by fallout from the Chernobyl accident, and from three herds in northern Norway which was unaffected by fallout from the accident. Significant heterogeneity in the distribution of chromosome aberrations between herds was observed. The pattern of chromosome aberration frequencies between herds was not related to the variation in radiocesium exposure from the Chernobyl accident. Other factors than the Chernobyl accident appear therefore to be of importance for the distribution of aberration frequencies found among present herds. Within the most contaminated area the reindeer born in 1986 showed significantly more chromosome aberrations than those born both before and after 1986. This could suggest that the Chernobyl accident fallout created an effect particularly among calves, during the immediate post-accident period in the most exposed areas.

Animals↗

Chernobyl fallout and perinatal mortality in England and Wales.

Previous studies have concluded that radioactive fallout from Chernobyl may have caused an increase in perinatal mortality in West Germany and the U.S.A. The existence of marked geographical variations in contamination from Chernobyl in England and Wales provides an opportunity to investigate this question further by means of a geographical study. The highest doses from Chernobyl in England and Wales were in the counties of Cumbria, Clwyd and Gwynedd where there was heavy rainfall during the passage of the radioactive cloud. However, perinatal mortality in these areas did not rise relative to the national average in the year following Chernobyl. This negative finding was confirmed by a wider study of 14 counties grouped in accordance with levels of radioactive contamination of local milk. It is concluded that this study provides no evidence that radiation from Chernobyl caused a rise in perinatal mortality in England and Wales.

Accidents↗