[SUBSTANTIATION OF DOSE LIMITS FOR A NEW NORMATIVE DOCUMENT ON RADIATION SAFETY OF LONG-DURATION SPACE MISSIONS AT ORBIT ALTITUDES OF UP TO 500 KM].

Review of the data of experimental radiobiology and epidemiological follow-up of large groups of people subjected to radiation exposures on Earth has been undertaken to substantiate dose limits for critical organs of cosmonauts in order to ensure good performance and vitality while on long-duration orbital missions. The career dose limits for cosmonauts and astronauts established earlier in the USSR and USA amounted to nothing more but banning the risk of cancer death increase to 3%. To apply more rigorous criteria of delayed radiation risks, the Russian limits for cosmonauts were revised to substantiate a 4-fold reduction of the average tissue equivalent dose maximum to 1 Sv.

METHOD FOR ANALYSIS OF HEART RATE REGULATION STRAIN BY APPLICATION OF THE OVERALL LOGARITHMIC INDEX TO THE HOLTER ELECTROCARDIOGRAM MONITORING.

Studies of human adaptation to extended exposure in extreme environments necessitate the development of integral indexes for quantitative evaluation of the functional systems of organism. The study was performed using an integral overall logarithmic index to analyze changes in heart rate variability (HRV)' over 20-hour monitoring of patients examined in a hospital. HRV-evidenced adaptation processes were compared to the data of Holter monitoring of patients and normal values for healthy people under 30 years of age.

[BIOLOGICAL EFFECTIVENESS OF FISSION SPECTRUM NEUTRONS AND PROTONS WITH ENERGIES OF 60-126 MEV DURING ACUTE AND PROLONGED IRRADIATION].

Neutrons of the fission spectrum are characterized by relatively high values of linear energy transfer (LET). Data about their effects on biological objects are used to evaluate the risk of delayed effects of accelerated ions within the same LET range that serve as an experimental model of the nuclei component of galactic cosmic rays (GCR). Additionally, risks of delayed consequences to cosmonaut's health and average lifetime from certain GCR fluxes and secondary neutrons can be also prognosticated.

[Overall logarithmic index for the characterization of adaptation and regulatory systems straining under chronic action of extreme environmental factors].

The article advertizes some optional capabilities of the overall logarithmic index as an integral parameter for quantifying adaptation processes triggered by chronic exposure to stress factors of varying intensity. Consideration is given to the principles of damage formation in different systems of organism with time and subsequent compensatory processes depending on the level of regulation system straining, rate of functional potential depletion, probability of remote consequences such as early aging, increased risk of lethality and reduction of the mean remaining life expectancy. The overall logarithmic index will be used to analyze the transition from normal to active insufficient adaptation, and possible adaptation failure because of a drastic decline of organism resistance.

[Cytogenetic investigations of mice marrow cells after isolated chronic exposure to radiation and chemical factors, and combined sequential exposure to these factors].

The article presents data on chromosomal aberrations in bone marrow cells of mice following isolated exposure to gamma-radiation and chemical factor within the existing MPCs for piloted spacecraft, and also combined sequential exposure in the ranges predicted for interplanetary missions. In the event of chronic exposure the relative number of chromosomal aberrations goes up till reaching plateau and is governed strictly by the mathematical dependence on effective residual gamma-dose and effective damage of organism from inhaled chemical factor. Sequential exposure to the radiation and chemical factors within the ranges specified for orbital and remote space missions caused a tangible reduction of the speed of cytogenetic damages reparation in postexposure period which may be interpreted as depletion of the body reserve and compensatory-recovery potential.