Environmental Radiation Effects on Mammals - A Dynamical Modeling Approach (Electronic book text)

This monograph is devoted to theoretical studies of radiation effects on mammals, particularly as they affect mammals as they travel in space for lengthy periods of time. It summarizes the results obtained by the author herself over past 30 years. Specifically, the effects of both acute and chronic irradiation in a wide range of doses and dose rates on vital body systems (hematopoiesis, small intestine, and humoral immunity), as well as on the development of autoimmune diseases, are investigated in the framework of the developed deterministic mathematical models. The radiation effects on the mortality dynamics in homogeneous and nonhomogeneous (in radiosensitivity) mammalian populations are studied by making use of the proposed stochastic models. The elaborated models of radiation-induced mortality could particularly be applied to estimate the risk of long-term irradiation in manned space missions (voyages to Mars, lunar colonies, etc.).The most appealing feature of these mortality models consists in the fact that they account for the intrinsic properties of the exposed organism. Namely, within these models the stochastic biometrical functions are calculated proceeding from statistical and dynamic characteristics of the respective critical body system (hematopoiesis or small intestine).

The performed investigations are of a great theoretical importance. They contribute to the development of the system and quantitative approaches in radiation biology and ecology. These studies elucidate the major regulatory mechanisms of the damage and recovery processes running in the vital body systems of exposed mammals and reveal the key parameters characterizing the processes. Proposed explanations of some paradoxical effects of low level single/protracted irradiation on the vital body systems, on the organism as a whole, and on nonhomogeneous mammalian populations are of a particular theoretical significance since these effects still have no unambiguous interpretation.

The material presented in the monograph is a matter of interest to the practical use, too. In particular, the modeling studies of the radiation-induced mortality in nonhomogeneous populations eventually led to the formulation of the criterion, which enables one, using routine blood sampling, to reveal the hyper-radiosensitive individuals (a group of elevated radiation risk) among people exposed to low dose rate chronic radiation. Obviously, the implementation of this criterion into the medical practice would allow one to carry out more effectively preventive and protective measures among persons subjected to occupational irradiation (power plant employees, radiologists and technicians, and many others).

The models of the radiation-induced mortality lay down the theoretical foundations of a new individual-based approach to the radiation risk assessment. These models enable one to predict the mortality dynamics and the average life-span shortening for an individual and for populations exposed to acute and, that is most important, to low level chronic irradiation. Therefore, the mortality models could be used, for instance, to evaluate the hazards for a population, which resides in contaminated areas after an accident/incident, including airborne dispersion of radioactive materials. In turn, this would help the decision makers to distribute, in an optimal way, the available resources to reduce the total risk for the population.

Thus, the uniqueness of the monograph consists in the fact that the wide range of the fundamental problems in the fields of radiation biology and ecology are investigated therein in the framework of the single approach by making use of the methods of mathematical modeling. Therefore the developed methodology of the studies, the elaborated models themselves, and the obtained theoretical results can be of benefit to academic institutions, scientists, and researchers working in the field of mathematical modeling of biological systems, as well as in the field of radiation biology, ecology, and medicine. The uniqueness of the monograph consists also in the fact that the theoretical investigations presented therein can find the wide practical use. In particular, the monograph can be of benefit to Aerospace companies and to corporations that deal with the problems of the environmental protection and the radiation safety, as well as to practitioners and professionals working in these fields. The monograph can be used as a basis for a lecture course on mathematical modeling in radiation biology and ecology. It can be of benefit to undergraduate and graduate students of appropriate specializations.