§ Mr. Fortasked the Prime Minister whether he is aware that the figures of 100, 22 and between 1 and 2 which have been given for the proportions between radiation from natural sources, from manmade sources other than nuclear tests, and from nuclear tests, apply only to the genetic effects of radiation; and whether he will give comparable figures for the somatic effects.
§ The Prime MinisterYes. The proportions of 100, 22 and between 1 and 2, which I quoted on 5th May, apply to the possible genetic effects of radiation. As for the somatic effects, the 1956 Report of the Medical Research Council on the Hazards to Man of Nuclear and Allied Radiations gives the annual dose of radiation to bone from 1 strontium unit of strontium 90 (which is about the national average) as about 3 millirems a year. This has to be compared with the average annual dose to bone from naturally occurring radium in the bone of 37 millirems a year, and the natural gamma radiation from the environment of 80 — 180 milli-190W nems a year in the United Kingdom. So, on the basis of this provisional estimate in 1956 the amount of radiation from the everage quantity of strontium 90 in human bone in this country was somewhere between 1.4 and 2.6 per cent. of the comparable radiation from natural sources.
The United Nations Scientific Committee in their Report last year used different figures which led to an average figure of 2 per cent. for the ratio between strontium 90 and natural radiation to bone. It may be that the slight increase in the deposition of strontium 90 which has recently been recorded in the United Kingdom may in the future put this percentage up slightly. No estimate of the dose to bone from medical radiology is at present available, but this will be included in the final Report of the Adrian Committee.