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.