[en] This paper is a synopsis of a talk which factually summarised the latest recommendations of ICRP 26 and 30. In this, important new conceptual developments are indicated: e.g. 'risk factor' related 'weighting-factors', annual whole body exposure limit based on comparative risk, ALI and DAC. Other concepts such as 'cost-benefit analysis', 'action level', 'recording level', 'working conditions A and B' are outlined. Critical reviews of some of the aspects of these latest recommendations were part of the talk but not included here. This bare summary is aimed at the helping clear understanding of the latest recommendations. (author)

No abstract available

[en] A comparison of the findings including health effects in four major high natural background areas of the world are given. Such high background areas could prove to be a radiation ecology laboratory gifted by nature and provide further insight in the relation of radiation, natural or otherwise and human health. 3 refs., 2 tabs

[en] The concept of risk from radiation exposure in the International Commission on Radiological Protection (ICRP) publications is surveyed. The ICRP on radiation protection publication 26 is considered the basic document explaing the fundamental principles of the system of dose limitation. The ICRP publication 27 introduces a method of calculating the time lost from healthy life irrespective of the agent of harm either due to radiation accidents or any other course. The ICRP publication 45 mentions the 'unified index of harm'. It indicates that cancer mortality is a major contributor to industrial workers exposed to radiations. Risk estimates prepared will help in planning radiation work. (M.G.B.)

[en] Estimates of exposure from various radiation sources to Indian population are given. The per caput dose from all the identifiable sources, both natural and man-made is estimated to be 2490 μSv per year to the present population of India. 97.9% of this dose is contributed by natural sources which include cosmic and terrestrial radiations, 1.93% by medical sources used for diagnostic and treatment purpose, 0.3% by exposures due to activities related nuclear fuel cycle, nuclear tests and nuclear accidents, and 0.07% by miscellaneous sources such as industrial applications, consumer products, research activities, air travel etc. The monograph is written for the use of the common man. (M.G.B.). 25 refs., 7 tabs., 7 figs

[en] The new concept of weighting factor for each target tissue (WT) based on the concept of whole body risk estimates has made it possible to add radiation dose due to internal contamination with measured external whole body dose. In this note, a method is discussed to find whole body dose due to internal contamination using the ALI (Annual Limit of Intake) concept. The desirable frequency of body burden measurement for a reasonable estimate of organ doses given in ICRP publication-10 is also discussed. Based on this method of dose calculation the problems of laying off persons from radiation work in case of excessive exposure and questions about subsequent dose records, especially in the case of long lived isotopes, are also discussed. (author)

[en] Radiological Protection Dosimetry Section has as its objective development of dosimetric techniques, theoretical as well as experimental. To this end in view, research and development work on chemical and neutron dosimetry systems, computational dosimetry and dosimetry associated with protection problems is being done. Work is also carried out on radiobiological investigations at cellular level to understand radiation damage and interpret the basis of radiation exposure limits and attendant safety standards. These topics are covered by five groups in the section viz. Neutron Dosimetry, Chemical Dosimetry, Radiation Biophysics, Radium Hazards Evaluation and Control, and Theoretical studies. A brief outline of the activities of each of the above groups is given along with a list of publications for the last two years. (author)

[en] Metronidazole (Flagyl; 2-methyl-5-nitroimidazole-1-ethanol) is of potential clinical application as a radiosensitizer. Studies have been made of the effect of 1mM metronidazole on γ-induced heteroallelic recombination (reversion) under euoxic or hypoxic conditions in yeast strain BZ34, and compared with the effect on survival. The o.e.r. for reversions was 2.2, and very close to that for survival (2.3), indicating that oxygen equally sensitized gross cellular events such as killing, and genetic phenomena like reversions. The introduction of metronidazole during irradiation sensitized cells with killing as the end point only in hypoxic condition, whereas with reversion as the end point no sensitization due to the chemical was observed either in euoxic or hypoxic conditions. Since DNA damage is responsible for both cell-killing and mutations, the sensitizer might have been expected to have had an equal effect on both these end-points. The results show that only in a limited sense can metronidazole be considered to be an oxygen mimic. (U.K.)

No abstract available

[en] This paper reviews the use of hypoxic sensitizers metronidazole and misonidazole in radiotherapy. This also includes the effects of these sensitizers on radiobiological parameters such as split dose recovery, toxicity, mutagenicity etc. at cellular level as well as some pharmacokinetic data from clinical trials. The possible use of these sensitizers for new combined modality treatments as hyperthermia, combination with protectors and sensitizers etc. is elucidated. (auth.)