FOREWORD 



1. Does the genetic effect of radiation show a Hnear dose-effect relationship 

 down to the levels of natural background and below ? 



2. If not, how does the genetic effect of relatively small amounts of ionizing 

 radiation on a standard human being vary with the total dosage, its physical 

 quality and the time course of its administration ? 



3. What is the relative susceptibility to genetic damage of the foetus, the 

 child and the adult? 



4. Are the carcinogenic and leukaemogenic effects of radiation due 

 essentially to the same mutagenic processes as are responsible for genetic 

 damage ? If so, are secondary ' promoting' factors also concerned in allowing 

 the emergence of overt disease ? Or, as Kaplan has suggested, is the whole 

 effect unrelated to mutagenic action of radiation ? 



5. Whatever the process of carcinogenesis, knowledge on the influence of 

 dose, quality and rate of administration, and of the relative susceptibility at 

 different ages will be needed. 



Until these questions can be answered, I believe we are justified in accepting 

 some empirical rules for action: 



1. All ionizing radiation is potentially harmful and the degree of exposure 

 should be reduced to the lowest possible level that is consistent with the 

 fulfilment of acceptable medical, industrial or military needs. 



2. Exposure to artificial radiation not greater than the dosage always 

 being received from natural sources is of no significance in comparison with 

 normal hazards of life. 



3. The potential benefit of any intelligent medical use of X-rays will far 

 outweigh any risk of radiation damage. 



4. The accepted international levels of permitted exposure in nuclear 

 laboratories, etc., form a reasonable basis for action. 



It is the task of conferences such as this to provide the background of 

 quantitative knowledge that will allow us eventually to replace these empirical 

 rules with scientifically valid recommendations. Only then are we likely to 

 escape from the emotionally charged atmosphere of suspicion, controversy 

 and misunderstanding that seems to rise in a stifling cloud whenever radiation 

 hazards become a topic of political discussion. 



I look forward very much to hearing the papers and discussions of this 

 Conference. I am confident that it will help to stimulate research in Australia 

 and aid understanding of the impact of radiobiology on human affairs. 



I have much pleasure in declaring the Conference open. 



vn 



