§ Captain Kerbyasked the Parliamentary Secretary for Science if he is aware that, in over 700 examinations of strontium 90 in human bone, only three were of children between the ages of one and five years, when new bone is most rapidly laid down, living in the West areas most highly contaminated by strontium 90; if he will arrange that the Atomic Energy Authority should take a larger proportion of its specimens from such children; and if he will make a statement.
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§ Mr. Denzil FreethThe mortality in this country in the age group of 1–5 years is extremely low and this limits the collection of bone samples from such children in any area, which in any case depends on the co-operation of the bereaved parents. The importance of the samples obtained from this age group is fully recognised and every effort is made to collect as many, and in as many areas as possible.
§ Captain Kerbyasked the Parliamentary Secretary for Science whether at any official research unit a study is being made of the incidence, past and present, of cancer and leukaemia in wet areas in Great Britain in which the strontium 90 levels are already known to be higher than in other areas.
§ Mr. Denzil FreethYes. The Medical Research Council's Clinical Effects of Radiation Research Unit, in conjunction with the Council's Statistical Research Unit, are at present undertaking a detailed study of the geographical distribution of leukaemia and bone tumours in Great Britain for the period 1945–60. No consistent relationship between the amounts of rainfall and the occurrence of these conditions has yet been demonstrated but, in the course of this study, an examination for any such relationship will be undertaken.
§ Captain Kerbyasked the Parliamentary Secretary for Science if he is aware that figures of strontium 90 in milk from some wet areas in the United Kingdom indicate that some strontium 90 levels in human bone are already above the 33.5 micro-micro-curies per gramme of calcium, given by the Medical Research Council as the warning level at which a re-assessment of the situation would be required; whether such a re-assessment is taking place; and if he will make a statement.
§ Mr. Denzil FreethThe Medical Research Council, in its Second Report on The Hazards to Man of Nuclear and Allied Radiations, considered the hypothetical case of the highest possible level which might have been reached in a wet hill area where the dietary contamination was highest. It concluded that it was unlikely that the level in the new bone of any individual could have exceeded 20 micro-micro-curies of strontium 90 per gramme of calcium in 59W 1959. Since the assumptions made in this calculation were extremely pessimistic, the Report commented that it was not surprising that this level was twice as high as the highest value then observed, namely 9.5 micro-micro-curies of strontium 90 per gramme of calcium.
I am not aware of any evidence indicating that the level of strontium 90 in the bones of any individual in this country has reached 33.5 micro-micro-curies per gramme of calcium. Moreover, the maximum permissible level of strontium 90 in bone for any individual member of the population was given as 200 micro-micro-curies per gramme of calcium by the Medical Research Council in its second Report on The Hazards to Man of Nuclear and Allied Radiations (Cmnd. 1225, 1960).
The circumstances in which the Medical Research Council recommended that immediate consideration would be required were those in which bone levels in a population group were found to be rising continuously and to have reached 33.5 micro-micro-curies of strontium 90 60W per gramme of calcium. In the absence of further nuclear testing it is considered unlikely that such a situation will arise. Nevertheless, the levels of strontium 90 deposited in this country on the ground, in foodstuffs, and in human bones are the subject of an extensive and continuing monitoring programme, and the significance of the levels observed is kept under close and continuous review by the Medical Research Council