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Enhancing Nuclear Safety


Research

The effects on health of chronic contamination with a low dose of radionuclides

(juillet 2011)

RESEARCH allowing the evaluation of radionuclide-related risks and their impact on health

The ENVIRHOM-Santé experimental research programme or Understanding the effects on health of chronic contamination with a low dose of radionuclides

The brain: A new target organ to uranium

Is the xenobiotic detoxification system affected by chronic exposure to uranium ?

Chronic ingestion of caesium 137 in a post-accident situation

Chronic exposure to caesium 137: Experimental and epidemiological studies

Metabolomics: Application in radiotoxicology

The perspectives of the ENVIRHOM-Santé programme

Chronic ingestion of caesium 137 in a post-accident situation

Changes in the cardiovascular system in rodents


Cardiovascular system impairment has been described in the literature following the Chernobyl accident. Myocardial lesions and haemodynamic changes were observed in liquidators (Shashlov and Vlasov 1991), together with cardiac arrhythmias and arterial hypertension in children living in contaminated areas (Bandazhevskaya et al., 2004). However, to date, only one study focusing on the consequences of exposure at post-accident doses of caesium 137 on the cardiovascular system has been undertaken in laboratory animals (Bandazhevsky and Lelevich 1995).

In order to analyse whether disturbances of this system are due to the absorption of caesium 137 through the food chain, an experimental model of rodent exposed via the drinking water with a caesium 137 concentration of 6500 Bq.l-1 was used. Surprisingly, subtle yet significant changes in the cardiovascular system were observed in this way (Gueguen et al., 2008b):, plasma concentrations of markers indicative of cardiac damage (CK, CK-MB) increased significantly after 3 months’ exposure to caesium 137. In man, such an increase of these parameters could indicate cardiac muscle alteration like it has already been seen in liquidators exposed during the Chernobyl accident. It should nevertheless be emphasised that histological analysis did not highlight any structural alteration of the cardiac tissue and that other markers of cardiac muscle involvement (troponin I, myoglobin) did not change.

figure 3

figure 3

Assay of biochemical clinical parameters in the plasma (CK, CK-MB, electrolytes); electrocardiogram (ECG) typical of animals in the control group or those in the contaminated group (caesium 137); recording of arterial pressure over 48 hours in the control rats (blue) and rats contaminated with caesium 137 (red); and measurement at cardiac level of the gene expression of potassium and protein channels regulating vascular tone.

In biological terms, the gene expression of enzymes or proteins involved in vascular tone (ACE, angitensin converting enzyme, BNP, brain natriuretic peptide) and potassium transport (Kir-6) is modified in the cardiac tissue of rats exposed to caesium 137 for 3 months. Concerning the clinically measured effects, a decrease blood pressure and the disappearance of its circadian rhythm were observed. On the other hand, electrocardiogram analysis (ECG, Figure 3) did not disclose any arrhytmia in rats exposed to caesium 137, contrary to observations in children living in the contaminated areas (Bandazhevskaya et al., 2004). The question relating to the effects on rats exposed to caesium 137 for longer time or exposed from a younger stage (offspring) has yet to be answered, similar to the question on multi-pollution effects.

Furthermore, the arrythmogenic effects of Cs+ non-radioactive ions have been demonstrated elsewhere after exposure to elevated concentrations. The effects observed in our study by a very low mass concentration of caesium 137 may therefore result from its the radiological properties.

To conclude, the few studies carried out on the effects of internal contamination with caesium 137 are inconclusive as regards any possible increase risk of cardiovascular diseases following the ingestion of this radionuclide. Additional studies in animals and epidemiological studies in man are therefore necessary in order to provide a more accurate response to this point and to identify the mechanisms involved. The EPICE programme1 conducted by the IRSN and focusing on children living in contaminated areas, should provide some answers.

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références :

1 : In October 2005, IRSN launched a study entitled EPICE (French acronym for “Assessment of the pathologies induced by chronic caesium contamination”). The objective of this study was to measure the distribution of caesium in children living in the Bryank region, which is the most contaminated of Russia, but also to establish whether there is a link between the level of contamination by caesium and the pathologies observed in these children.

Bandazhevskaya GS, Nesterenko VB, Babenko VI, Yerkovich TV, Bandazhevsky YI (2004) Relationship between caesium (137Cs) load, cardiovascular symptoms, and source of food in 'Chernobyl' children -- preliminary observations after intake of oral apple pectin. Swiss Med Wkly 134:725-729.

Bandazhevsky YI (2003) Chronic Cs-137 incorporation in children's organs. Swiss medical weekly 133:488-490.

Bandazhevsky YI, Lelevich VV (1995) Clinical and experimental aspects of the effect of incorporated radionuclides upon the organism. Belorussian Engineering Academy - Gomel State Medical Institute, Gomel, Belarus.

Gueguen Y, Lestaevel P, Grandcolas L, Baudelin C, Grison S, Jourdain JR, Gourmelon P, Souidi M (2008b) Chronic contamination of rats with 137 cesium radionuclide: impact on the cardiovascular system. Cardiovasc Toxicol 8:33-40.

 Shashlov SV, Vlasov PA (1991) [Morphologic characteristics of the myocardium of people dying after the Chernobyl Nuclear Power Station accident]. Arkh Patol 53:45-48.

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