In the maintenance and development of sound standards of radiation protection, many types of enquiry are important. These range from the purely technical examination of the ways in which exposure may occur or radionuclides may enter the body under existing or new conditions of occupational activity, to the most fundamental studies of the interaction of high energy particulate radiation with matter or the metabolic localisation and kinetics of unfamiliar radionuclides. One of the most important, and most basic, problems, however, is to establish a quantitative estimate for the frequency with which various types of injury would be induced in man following exposure to low doses of radia tion delivered at low dose rates. No sound limits can be proposed for appropriately safe levels of occupational or population exposure unless the associated hazard-or its maximum likely value-can be at least approximately assessed. It is one of the most important tasks of those concerned with radiation protection that these criteria should be kept under constant review in the light of developing knowledge, and that the fields in which further information is needed should be defined and described.

General Review of Biological Aspects of Radiation Protection

Problems of Protection against the Genetic Effect of Radiation
Radiation Risk and Protection (with Reference to Recent ICRP Reports)
Radiation Effect on Prenatal Development
Comparative Late Effects in Mice Following Fast Neutron or Cobalt 60 External Irradiation Versus Tritiated Thymidine Internal Irradiation
General Discussion
Hematological and Cytogenetic Effects of Radiatio
Hematological Effects of Partial Body Irradiation: Clinical and Experimental Data
Hematological Effects on Heavily Irradiated Japanese Fishermen
Cell Population Kinetics in Thymus Lymphocytes under Continuous Irradiation
Radiation-Induced Chromosome Aberrations in Lymphocytes: Possible Biological Dosimet in Man
Some Hematologic Changes Due to Ionizing Radiations
Feasibility of Cytogenetic Assay in Radiophosphorus Dose Assessment
General Discussion
Chemical Protection in Mammals
Radiation Protection of Non-Specific Body Defence: Reticuloendothelial System and Adrenal Cortex
Mode of Radioprotective Action of Aminothiols in HeLa S3 Cells
Radioprotective Effect of Methylene Blue in Mice and Rats
Radioprotective Effects of Adenosine Derivatives
Chemical Radie-protection with N- and S-Containing Polymers
New Potentialities of Combination of Radioprotection and Cyclophosphamide
Histopathological Action of Serotonin on Certain Tissues in Mice
Comment and Discussion
Fundamentals of Radiation Protection and Recovery
Chemical Protection and Cell Structure
Metabolism of Ehrlich Ascites Tumor Cells under "Anoxia" and Its Implication in the Rejoining of X-Ray-Induced DNA Strand Breaks
Chemical Protection of the Recovery Process
Cysteamine and Radiation-Induced Single Strand Breaks of DNA inCultured Mammalian Cells
Comparative Individual Radiosensitivity and its Cellular Explanation
Animal Survival and Cell Survival Seen in Dose Rate Effects on Mouse Intestinal Damage
Mortality of Fish under Continuous Irradiation Conditions
Relationship between Metabolism and Radiosensitivity
Medical Aspect of Chronic Hypoxia in Radiation Exposed Glomerulus in Hamsters Treated with Injected Ozone Gas
Low Dose Effects of X-Rays on Electrophoretic Mobility of Human Erythrocytes
On Mechanisms of Chemical Radioprotection
Comparative Radiosensitivity of Ascites Ovarian Tumors and Ascites Lymphosarcoma of Rats
General Discussion
Closing Remarks
List of Participants
Authors Index
Subjects Index.