HL Deb 24 October 1961 vol 234 cc659-72

2.44 p.m.


My Lords, I beg leave to ask the Question which stands in my name on the Order Paper.

[The Question was as follows:

To ask Her Majesty's Government whether they will make a statement about the level of radioactive fall-out resulting from the resumption of nuclear tests by the U.S.S.R., and whether they will give an assessment of the present and future hazards to the population of this country resulting from these tests.]


My Lords, before the Leader of the House replies to the Question, may I inform the House of what I have put to him also? I have put the further Question by Private Notice: To ask whether Her Majesty's Government will make a statement with regard to the nuclear tests carried out by the U.S.S.R., with the latest information they have, including the estimated fall-out. I understand that the noble and learned Viscount will endeavour to answer both Questions in the one statement.


My Lords, I should like to ask the indulgence of the House, as the noble Viscount the Leader of the Opposition has indicated, to allow me to answer together both the Question standing in the name of the noble Lord, Lord Taylor, and the Question of which the noble Viscount the Leader of the Opposition has given Private Notice. I am grateful to both noble Lords for thus enabling me to provide some information on this important subject to Parliament before Prorogation, and in a form which will allow some further remarks to be made, if this is desired—though I hope that we shall not get into a regular debate, since this would be out of order; and, in any event, noble Lords will wish to study the more detailed statement which is being issued by the Medical Research Council this afternoon. In part of what I want to say, I will stick pretty closely to my notes. But first I should like to make two general observations.

A full scientific assessment of the effects of the recent tests is quite obviously premature. The tests are not, so far as I know, complete. We do not know the exact nature of the devices used, nor the height at which they were exploded, and the fall-out will not have begun to show its true pattern for a number of months. Nevertheless, I think that the public is entitled to an informed commentary on what is going on, and that is why I have arranged for the Medical Research Council to issue, this afternoon, a fuller statement of which the reply I am about to give is—as regards assessment of the effects of the tests—a summary.

My second observation is that, as regards the immediate future, I regard the statement by the Medical Research Council as reassuring. At the same time, I should like to emphasise that this should not in any way be considered to qualify what I said on the subject in the Foreign Affairs debate last week. What has happened is extremely serious. The safety margins are being eaten up. The breach, by one nation, of the moratorium may not remain the only case; it is liable to lead, sooner or later, to other Powers doing the same. The explosions that have recently taken place are, in my view—and the explosion of anything like a 50-megaton bomb certainly must be considered, on any objective view—an offence against humanity.

As regards the information asked for in the earlier part of the Private Notice Question of the Leader of the Opposition, I think the best thing I can do is to repeat what was said by my right honourable friend the Minister of Defence in another place this morning. He said:

"As the House knows, the Russians are engaged on a series of nuclear tests and, up to yesterday's date, had exploded well over 20 weapons, giving a total of well over 20 megatons.

"Yesterday morning, two further devices were exploded. The first gave the greatest yield of any device yet exploded in the atmosphere. It must be some time before Western scientists can make any accurate assessment of either the total yield of this device or of its nature. Preliminary evidence suggests a yield of the order of 30 megatons.

"The second device exploded two hours later was a small yield and was exploded under water.

"We cannot of course say whether this concludes the present series of tests or whether further explosions will take place."

As regards fall-out, mentioned in the latter part of the Question asked by the Leader of the Opposition and the Question of the noble Lord. Lord Taylor, the radioactivity reaching the ground in recent weeks has come mainly from short-lived components, including radioactive iodine, which are deposited within a few weeks of the explosion. The deposition of longer-lived components, such as strontium 90 and caesium 137, is likely to be greatest next spring.

Radioactive fall-out is monitored in the United Kingdom under a country-wide scheme, and the results are published. The House might like to know that the country-wide sample comes from over 200 depots taken once a week; and in addition, daily, or sometimes every two days, samples for iodine are taken from a representative selection of points, at present about a dozen as a check. As the levels of radioactivity measured in air have so far been similar to those observed at an equivalent time after explosions in the autumn of 1958, there is at present no reason to believe that tests from which fall-out has so far been detected will involve an additional radiation exposure from external radiation or from strontium 90 differing greatly from what has been experienced hitherto.

It may be concluded that strontium 90 from tests so far carried out will not give rise to bone levels approaching those which the Medical Research Council regard as the maximum permissible in the general population. I should like to say that that applies even after yesterday's tests, and even in the light of possible future tests in the present series.

In view of the rapid deposition of short-lived fission products observed following explosions in high altitudes during the autumn of 1958, extensive measurements are being made of levels of iodine 131 contamination following the present series of tests. The importance of this isotope is that it becomes concentrated in the thyroid gland. Consequently, although its radioactive half-life is only eight days, it may give doses comparable in significance with those delivered over much longer periods by the longer-lived materials produced in the same explosions.

Since iodine 131 is taken into the body predominantly through milk, the Medical Research Council have had under review the levels in milk which might be regarded as allowable. They have concluded that an acceptable dose would not be exceeded in any age group of the population unless an average concentration of iodine 131 in milk of 130 micromicrocuries per litre—that is a millionth part of a millionth part of a curie—was exceeded over a period of one year, or higher levels for correspondingly shorter times—for instance 520 micro-microcuries per litre for three months in one year. This criterion has been set to provide a margin of safety for the section of the population in which the dose received would be highest—namely infants in their first year of life. Considerably lower radiation doses would be received by older children and adults consuming the same milk. This, of course, is partly due to the composition of their diet, and partly due to the rate at which glands absorb the iodine. In framing this recommendation allowance has been made for the likely variation in the concentration of iodine in local milk supplies. It should be emphasised that the figure of 130 micro-microcuries per litre is quoted as a twelve-month running average level and that wide variations in individual milk samples are to be expected.

During the past month the general level of iodine 131 in milk throughout the United Kingdom has been about 120 micro-microcuries per litre. However, as a marked decrease may be expected within a few weeks of the cessation of tests, the level specified by the Medical Research Council will not be reached unless the present levels of iodine 131 continue for several months, or are substantially increased as a result of further weapon tests.

The explosion of a 50-megaton bomb during the present series of tests would cause the total energy released from this series to correspond approximately with that of explosions occurring in the two years 1957 and 1958. If the bomb is exploded in the atmosphere, the resulting fall-out will depend on the extent to which the energy is due to fusion rather than fission, and on the altitude and site of the explosion. My Lords, perhaps I should say, in parenthesis, that it is not at all the case that the amount of fall-out from a fusion bomb is related in direct proportion to the size of the yield. A contrary impression happened to be given on the radio last night, so I thought it might be worth while saying that.

The explosion of the bomb in the atmosphere in Northern latitudes during the autumn could be followed by considerable fall-out of short and medium-lived radioisotopes. The iodine 131 deposition due to the series might then be substantially greater than that from previous tests, and the contamination of milk in the subsequent weeks might cause the annual mean level to reach that specified by the Medical Research Council.

Radioisotopes of medium half-lives, such as zirconium 95, might be expected to raise the external radiation level in the open for some months by an amount comparable with the dose rate received from natural sources. It is not yet possible to predict with any accuracy the total additional radiation dose to which the population will be committed by the current series of Russian tests. Bone concentrations of strontium 90 in young children might rise in the course of one year to about twice the maximum level observed hitherto, but the level regarded in December, 1960, as the maximum permissible by the Medical Research Council would not be reached.

The Government are keeping close watch on the situation and considering measures that might be needed to meet future eventualities. Arrangements are being made to ensure that, should iodine 131 in liquid milk reach a danger level for infants of up to one year old, alternative forms of milk can immediately be made available for the necessary period.

That is the Answer to the noble Lords' Questions.


My Lords, may I ask the leave of my noble friend who has the Question down to intervene at the commencement, and to say how grateful we are to the noble Viscount the Leader of the House for the statement which he has given, and especially his own contribution to the statement? It is obvious that those of us who are not, like some of my noble friends, professionally qualified to deal with some of the considerable points that the noble Viscount has given will certainly require a good deal of time to study the details of this. In the meantime, I think we all want to express our horror at this ghastly and dastardly series of explosions which have been set off by the Russians, as if it were a special desire of one man, with those few who support him, to make war in peace time upon the infants of the world. That really is a very shocking thing. We shall have something more to say about that perhaps later on, but in the meantime I think we shall need to make a good deal of study of what should be the actual procedures of the Government.

They promise that they are going to take every possible care they can to keep the public informed and to take steps. I shall leave it to my professional friends to say whether, in the remedial measures the Government propose to take, consideration should not be given to whether making supplies of, say, dried milk available, or certain other actions to be taken, should not have to wait until we are certain that the danger to children has already been reached or surpassed. I put that as a general point for consideration to the noble Viscount the Leader of the House, and leave it to my other noble friends or Members of the House to put what other further questions they want.


My Lords, of course I associate myself with the expression of disgust at the action which I have had to describe, which the noble Viscount the Leader of the Opposition has expressed on behalf of his side of the House. I think we all agree with that.

As regards the other point, I think it is extremely important to remember that the point at which remedial measures will be taken is not the point at which, as you might say, the danger is actual, because at the moment it is exactly what the noble Viscount the Leader of the Opposition is suggesting —that is to say, it is what I might call the warning level. It is important also that people should not anticipate that, because otherwise you would have a lower warning level than necessary, and people would say, "We must have a lower one still". We will, of course, take what advice we can about this extremely important matter, but I think the general effect is that we must not ourselves be alarmed about this before it is really necessary. Although I fully realise the seriousness of what I have been saying, I think it is important not to put it any higher than I have put it.


My Lords, may I add my thanks to those of my noble Leader for the extremely clear and balanced statement which the noble Viscount the Lord President has given us of the risks of dangers and hazards through which we are now passing? I should like to thank also his really admirable scientific staff for the way they are carrying out this very delicate monitoring, and the extremely honest and objective way in which they are presenting results for him to present to us and, in due course, to the country. As I understand it, we shall know in a week or so after the termination of any series of tests whether this radio iodine is going to do harm, because it will have manifested itself quite quickly, and we can only hope that the present series was ended by these two devices exploded yesterday.

We have all been thinking much about the strange, bizarre pattern of thought which must go on in the minds of those who explode these devices, and one wonders whether perhaps the Lord President cannot, in his capacity as Minister for Science, set up a research committee to study the motivation of the Russians and the way their minds work, because I really think this is a very interesting problem of psycho-pathology which ought to be properly investigated as well as these purely objective medical results.


My Lords, may I ask the noble Viscount this? I understand that there was a specially big bomb exploded yesterday. Is that supposed to be the big bomb threatened by Mr. Khrushchev, or is that still to come?


My Lords, may I deal with both those supplementary questions in the order in which they were put? I should like to thank the noble Lord, Lord Taylor, for his kindly observations about the statement, and also, on behalf of the Agricultural and the Medical Research Councils, to thank him for his recognition of their services. It is a very great thing to be thankful for that we have this system of monitoring and assessment, which has now been built up ready for use in just this situation, based on experience and objectivity. We have tried to ensure not merely that the panel of advisers is medically beyond reproach—which it is —but also that whatever they say is absolutely uncoloured by any political bias in one direction or the other, and I think that when your Lordships read the Medical Research Council's statement you will see that they live up to that objectivity. The difficulty, of course, in dealing with matters of this kind is to make what is essentially complex simple, and they of course do their best. But any attempt at simplification is very apt to lead to some degree of distortion, and therefore I did in the course of my remarks add remarks of my own, as a layman, to try to indicate the immediate practical effect of some of the things I see as essentially important.

In answer to the noble Lord, Lord Rathcavan, I cannot of course say whether this was what Mr. Khrushchev was threatening. I can only repeat that it is said to have been a bomb of 30 megatons; that it took place before the end of the month—yesterday; and that what Mr. Khrushchev promised was 50 megatons at the end of the month.


My Lords, can the noble Viscount tell me, having regard to the hazards to health of these tests, why the Government yesterday told the country they were considering whether they should start tests again?


My Lords, what the Government said was that they reserved the right to make further tests. They said nothing else than that.


My Lords, may I ask my noble and learned friend this? As these various elements in the fall-out seem to have different lengths of life, is it the view of the experts that there is a time after which fall-out A, B or C, lying on the grass or in the trees or in the atmosphere, ceases to be harmful, so that one may expect after a time that the effect will not be cumulative for, say, the next decade or for ever and that it will clear un?


This is an extremely complex question. Broadly, the answer is, Yes. The position is that different radioactive isotopes have a different rate of decay. Fortunately, iodine, which is the one we have mainly been discussing this afternoon, iodine 131, has a relatively rapid rate of decay—an average half-life, as it is called, of eight days. That means, of course, that even if it stays up in the atmosphere, and does not come down for a long time, it is decaying up there, and therefore when it does come down after a reasonably short time it will be in a reasonably safe state. On the other hand, some of the others have a relatively long half-life; certainly strontium 90 has a half-life of 28 years, and of course it is coming down over a long period of time. As I indicated in the statement, it will probably reach its maximum in the spring of next year; it will not start coming down much earlier, owing to the effect by which it is yielded. It will not start coming down here until next spring, and even then, as it has such a long half-life, it will be active for a long time to come, and this is why it is generally considered a dangerous substance, even though in itself, and for any ordinary short period, it is not as dangerous as some of the other isotopes.

As regards the other part of my noble friend's question, I am again trying to simplify an extremely complex subject. Some of the isotopes, of course, wash away in the course of rain, and then they will go down to the rivers and into the sea and will cease to be tiresome. On the other hand, others will tend to accumulate in the soil, more or less rapidly; some will gradually be absorbed into the fabric of plants and trees; others—such as carbon 14—into the actual structure of living bodies such as ourselves. Indeed, we all have a proportion of carbon 14 in our bodies, quite independently of Mr. Khrushchev. The same is also true of strontium, which the body tends to take up in the same way as calcium, with which it has an affinity, and therefore it tends to concentrate in the bone. Subject to those qualifications, and, I am afraid, to many others, the broad answer is, Yes, the hazards will tend gradually to die out over a period of months.


My Lords, how does that answer affect the results of the under-water explosions? Has the Minister anything to say about the question of the possible effects upon health through food, and so on, in the sea?


My Lords, so far as we know, there is no danger to health through the under-water explosions.


My Lords, this, of course, is a crime against humanity and especially children, and a breach of undertakings previously given by the Soviet Government. May I ask the noble Viscount the Leader of the House whether it would not be wise for the Government to bring these imperialist, militarist aggressors before the United Nations so that the United Nations may be given an opportunity of giving judgment and asking the Soviet Government to cease this very, very antisocial conduct?


My Lords, I think that is a very wise suggestion, if I may say so. In fact what we are doing is to support a move which has been made by other nations in the United Nations, to do this very thing. My own feeling has been—I am told I am probably wrong about this—that any rational system of international law, like any rational system of municipal law, would render such acts wholly outside the pale of what was legal, and I still believe that sooner or later an international court will have the knowledge and judgment and jurisprudence to say so.


My Lords, this is a matter in which there is considerable concern in the country. We in this House who share that concern have had the opportunity of hearing the noble Viscount's statement. There have been, as your Lordships probably know, various articles in the Press and various programmes on television, some of which perhaps have been alarming—more alarming than the statement we have had this afternoon. There is so much concern that I wonder whether the noble Viscount would consider having a Government statement made on television similar to, but probably more simple in words than the one we have had this afternoon, to give some assurance to the people of the country.


My Lords, I think that that again is very desirable in one form or another. Whether a Government statement is quite the right vehicle I do not know. What I have tended to encourage hitherto—I am not of course in control of television programmes—is that some very reputable member of a panel, like Doctor Pochin, be approached by the television and broadcasting authorities to get this kind of statement. Of course, I could do this myself, but I do not carry the same scientific weight.


My Lords, in view of the fact that the new Session is not to start for a week, and if, unhappily, there is another explosion, could either the noble Viscount himself or his Department give an authoritative statement about the nature of such explosions rather than encourage possibly alarmist and ill-informed or not sufficiently informed speculation?


My Lords, again I take note of that suggestion. I think the responsibility for giving direct information about the explosions themselves had probably better remain with the Ministry of Defence, who are better qualified than I or my advisers to assess them, but it will, of course, take a matter of time even before yesterday's are properly assessed.


My Lords, I should like strongly to support the suggestion by the noble Lord, Lord Shepherd. About ten days ago there was an interview on television (I forget which service) which I think was extraordinarily alarmist and unfortunately very impressive. It must have been seen by millions of people in this country, so that it seems to me that what the noble Lord, Lord Shepherd, suggests is pure common sense. If the noble Viscount or the Government could see some way of getting the truth across, more or less as he has given it to-day, surely that would be a wise public service.


My Lords, I absolutely agree with the necessity of trying to get a balanced view of the truth. Unhappily, of course, the truth is complex and sometimes does not acquire the same circulation as something which is a little less true and a little more exciting.


My Lords, is it not the case that in fact we shall not know for some time the full effects of the fallout? Therefore, while we do not want to encourage a state of panic in the country, would it not be premature to assume that all is well and that if the Russians explode the 50 megaton bomb they are free to do so because it is not as bad as we thought? We really do not know for certain, and shall not know for some time, the full effects.


My Lords, while it is true that we do not know, and, as I pointed out in my statement, we shall not know the full effects of the fall-out for some time, I think we have taken care of that margin of ignorance to a very large extent indeed. I, personally, have been through this with the Medical Research Council and their expert advisers on a number of occasions in the last four years, and even as recently as this morning, and I feel quite confident on the whole that I have not erred on the side of over-optimism. I have tried very hard not to do so. In fact, I do not think I could be reassuring to anybody if I had not taken that precaution.


My Lords, could the noble Viscount indicate whether any steps are being taken in research as regards antidotes to radioactive fall-out if such antidotes exist?


My Lords, I must apologise for taking up so much time of the House, but the answer to that is, I think, that we do not really know, to anything like an adequate extent, the actual physics of the damage which radioactivity does. We are carrying on at Harwell and elsewhere some very extensive research of a fundamental character, and there is also some applied research. Broadly speaking, there are various approaches to the problem, of a fairly practical kind. Obviously, if one is dealing with a short-lived isotope the mere fact of processing means that it is delayed between the cow and the consumer to a point at which the short-lived isotope has decayed. Also, you could in theory, by adding certain substances to milk, reduce both the absorption of strontium and of iodine. But I do not think I could say more than that we do research in all these subjects. The most important thing to research into is the actual fundamental biology and physics of the damage caused to the cell by ionising radiation, and not nearly enough is known about that.


My Lords, the discussion has taken place very largely on how to deal with the problem of radioactive fall-out. May I support my noble friend Lord Morrison of Lambeth in pressing upon the noble Viscount, the Leader of the House, that what is necessary is action to prevent tests which produce fall-out?


My Lords, that I absolutely agree with. That is exactly what we have been seeking to achieve in the test-ban Conference for three years, and what it grieves us so much we have failed to achieve—through, I think, no fault of our own. We are taking the step I referred to before—supporting the smaller European nations in their protest.


My Lords, the noble Viscount said, in quoting statements made by the Minister of Defence, that of the two devices exploded yesterday the first gave the greatest yield of any device yet exploded in the atmosphere. Was he referring to the present series or to any device ever exploded, and, if so, are we to take it that this was a dirty bomb?


My Lords, as regards the first part of the question, I do mean that it was the biggest device ever exploded. The extent of dirtiness does not bear a direct relation to yield, partly because it depends upon the nature of the device employed and partly upon the height at which it is exploded. In theory, if it were exploded in space you would get either no or very little fall-out, for obvious reasons. Moreover, with fusion bombs, although fusion does create a certain amount of carbon 14 and there is, therefore, that factor in it, it does not really depend so much upon the fusion component of the bomb, which creates the size of the bang, as on the fission, which is used to trigger the bomb and which may also succeed the fusion at the end of the process. This causes radioactive fall-out very much in excess of the fusion process. Therefore, it depends very much on the size of the device and upon the height at which it is exploded.

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