Early signs of chronic radiation syndrome in residents of the Techa riverside settlements.

The review presents the results of a retrospective analysis of early markers of chronic radiation syndrome (CRS) in residents of the Techa riverside settlements. Mean values of postnatal red bone marrow doses calculated with the Techa River Dosimetry System-2016D were 698.8 ± 18.2 mGy, and maximum values reached 3 603.9 mGy. The clinical picture of the initial CRS stage was characterized by a set of non-specific functional changes that included not only hematopoietic but also immune, neurological, endocrine, and visceral disorders. CRS signs developed in a certain sequence. The earliest CRS signs were: increase of olfactory and taste thresholds, decrease of sensitivity to vibration and changes of systemic immunity. These were registered prior to hematopoietic changes typical of CRS. All initial organ changes related to CRS were functional in nature, mild or moderate, and transient. Early changes induced by chronic exposure in nervous, immune, and endocrine systems permit to consider CRS at early stages as a stereotype dysregulation pathology primarily based on radiation-induced disorders in regulatory systems. Disorders of circulatory, digestive, and other organs at early stages of CRS are secondary and their function restores spontaneously when the exposure stops. If exposure is continuous at doses sufficient for development of morphological tissue changes (dystrophy, fibrosis, hypoplasia and others), the CRS course becomes progressive and irreversible. The paper also describes the specific clinical manifestations of early stage of CRS in children.