Internal exposure in post-accidental situations: a multi-pollution to take into account?

International audienceMajor nuclear accidents (Chernobyl, Fukushima) induced the contamination of large areas with a mix of radionuclides (RNs), inducing both external and internal exposure at low dose and low dose rate. Numerous studies were conducted on the health effects in post accidental situations. However, in most cases, the exposure is ill-defined. Thus the health effects on exposed populations living in a contaminated territory remain a matter of controversy.Experimental results in rodents are somewhat in contradiction with results from the study of human populations. This might be due in obvious differences between rodent models and human physiology, but also could be due to simplified schemes of exposure used in the experimental settings. A hypothesis to explain these discrepancies is the differences in exposure schemes. Moreover, the exposure in real life is more complex than the simple exposure to ionizing radiation. In fact, the chemical pollution should also be taken into account.The hypothesis of a generalized model of interactions between chemical pollutants and radiological pollutants is reinforced by the recent descriptions of non-additive (either supra- or infra-) biological effects of mixtures of chemical pollutants. Since there is no available study on the health effects of mixed radiological exposures, it is not possible to exclude the hypothesis that a mixture of RNs may induce non-linear effects as compared to the effect of individual RNs. Thus it appears that futures studies on the health effects of radionuclides at low concentrations or external exposure at low dose rate should be done taking into account more realistic schemes of exposure, including mixtures of RNs, external exposure and chemical pollutants