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Alice Stewart, 93 anni, ancora sulla breccia (5 agosto)
In the 1950s, Alice Stewart found that exposing pregnant mothers to X-rays doubled the risk of cancer in their children. Ever since, the physician and epidemiologist has argued that low doses of radiation might be harmful. It's a view that has put her at odds with governments, the military and the nuclear industry. This week, Stewart, who is 93, publishes new research supporting her claims. Michael Bond spoke to the maverick of radiation epidemiology and found her in fighting form.
What new evidence do you have to support your claims that low-level radiation could be dangerous?
Radiation safety standards are derived from studies of the A-bomb survivors of Hiroshima and Nagasaki. These studies were food for people supporting hormesis, the theory that a little bit of radiation can be good for you -- that it stimulates the immune system. When it was found that a small number of the A-bomb survivors were living longer than they ought to, this was seen as proof that radiation had done them good. But we have new data that should put paid to that. We have proof that the A-bomb data have been wrongly interpreted. (See "Radiation: how safe is safe?")
What does your research show?
It shows that cancer was not the only effect of the A-bomb radiation. People died from immune system damage as well. Our paper also shows that the A-bomb survivors were not a normal, homogenous population. They were the best athletes -- the top 10 per cent -- and did not include the young and the old. This means that we cannot base standards of radiation safety on such an elite cohort.
Do you think that the authorities will now reassess the idea that radiation at low doses is not harmful?
I think this new paper will do it. But I don't think it will lead to an immediate reaction.
Why do you think your findings always take so long to be taken seriously? Take your work in the 1950s showing that a fetus exposed to X-rays has a higher risk of cancer. Or your findings in the 1970s that workers at the Hanford weapons complex in the US were getting cancer after supposedly safe levels of exposure.
The trouble is that I've always had a very small set-up, with only just enough money to employ people to do the research. I've never had a department that's out selling the message to other people. So it's been a bit slower than usual.
When it came to my work on X-rays, nobody wanted to believe it. X-rays were a favourite toy of the medical profession. But much more than that, it was just the moment when the nuclear industry was taking off. If we were right, the industry couldn't develop properly.
Your work has tended to attract a lot of criticism from scientists, one of whom is the leading epidemiologist Richard Doll. Why do you think he doesn't like your work?
I moved to Birmingham University for that reason. I knew that if I stayed at Oxford I would always be under the thumb of Doll. But that is the extraordinary thing. I can have reason to be angry with him because he was powerful and I was weak. He can have no reason at all to be angry at me, and yet he must resent me for some reason. Something irks him about me, and I'm conceited enough to think he suspects I'm a better epidemiologist than him. Now, he will tell you he has never had any quarrel with me at all.
Doll has criticised your methodology on the Hanford Studies. Why?
He's criticised my methodology from the word go. I don't know why. He's even criticised the mathematics of George Kneale, my statistician. But Doll doesn't know a fraction of the mathematics that George knows. I don't know what he means when he says our method is wrong, but he should be called to account.
The main objections to my X-rays study was that the mothers were lay informants -- that they weren't scientists, and they could have made up stories. We always knew there were weaknesses in our story. But we'd done our best to check this through the hospitals where they had their X-rays.
You've been described as "an avowed opponent of the nuclear industry". Are you?
Well, I've never avowed it to anybody. But if by the nuclear industry you mean the war and energy industries, then yes I'm against it. If you mean, do I think we should stop using X-rays, then no, but you must use them knowing they are a dangerous toy. I think the medical profession has quite a lot of uses for it. Take, for example, irradiated food. If this was going to prolong the life of food that you could send to a country to save it from starving, it would be excellent. But what you've got to be careful of is not to allow industry to indiscriminately use this radiation and to find it's going down your back drains.
I'm automatically against it for war, and you have to remember that the nuclear military and energy industries have always been far more intimately connected than most people realise.
The discovery that made your name in 1956 was that a fetus exposed to an X-ray is twice as likely to develop cancer within 10 years as one that is not. Did this finding come as a complete surprise to you?
Yes. We weren't particularly looking for a link between cancer and X-rays. We were comparing the medical records of children who had died from leukaemia with those of healthy children from the same regions. And in the questionnaire, we had asked mothers if they'd been X-rayed. It looked to me as if there had been something before birth that produced a little epidemic at a certain age group that never repeated itself. But the risk was so small that if we'd tackled it any other way we'd never have discovered it.
We were lucky, but it wouldn't have been thought of by someone who hadn't had some experience of medicine, and it might have been wrongly interpreted.
So if you hadn't found the link it might have been another 20 years before someone else did?
No, not 20 years. To this day we would be thinking X-rays were safe. This is because, as I've indicated, the A-bomb survivor studies from Hiroshima and Nagasaki, which was the only other study on this, was saying it was safe, and this would have been considered satisfactory to the point where everybody would have been quite happy about X-rays.
How much do you think being a woman helped or hindered your career? When you first walked into the lecture hall as a medical student at Cambridge in 1925 you were met with 200 male students stamping their feet at you.
I'm sure my sex made a tremendous difference. But thanks to my family -- my mother was a doctor -- and thanks to the war, rather than being a crippling difficulty it actually proved to be rather a helpful one. I found I was constantly thinking of things in an unusual way. I didn't expect to be allowed to get to the top rung, which is something a man would expect, and so perhaps that made it easier to stay with a subject that wasn't very popular.
Has that bothered you?
Not at the time, but in retrospect I think it's the one thing I rather regret . . . that I should have pressed for something more. But I was stuck, I could only do one or other of two things: I could either be fighting the battle for women or I could be getting on with my job. I couldn't win both. And I chose to go on with my job. But I think a braver person might have done something about it.
Were you ever bitter about being sidelined?
No, I think I personally had everything to gain by it. It's always worked in my favour. An element of uncertainty is always a good thing. It's been a constant help. You need some resistance and criticism to bring out the good work. One of the reasons it's been so interesting for me is that no one has ever lost interest in what I've said about radiation. They may despise me, they may hate me, but the problem is there and will stay there if nobody's solved it.
Most people think about cutting back on work when they reach seventy. Did you miss out on anything by carrying on in your nineties?
I stayed working because I was enjoying it, and it was all voluntary. It became obvious early on that we had hit on something that was going to take more than a lifetime to resolve. It wasn't just the radiation thing that interested me. I was really interested in where the other cancers were coming from. You need to follow it for a long time.
Who will carry on your fight in the radiation debate?
I've got a voice in the next generation in Steve Wing and his department at the University of North Carolina at Chapel Hill. Mind you, they're going to make life difficult for them, with grants and everything. People in the nuclear industry will do their very best to stop it. But I'm a great believer that in the end, they'll get caught up in their own machinations and the truth will emerge from an unexpected quarter.
- "A bomb survivors: factors that may lead to a re-assessment of the radiation hazard", International Journal of Epidemiology, Volume 29, no 4 (4 August 2000)
- The Woman Who Knew Too Much by Gayle Greene, University of Michigan Press, £19.99, ISBN 0472111078
Alice Stewart -- maverick, pioneering British epidemiologist -- is a legend among anti-nuclear activists. Her discoveries about radiation have revolutionized medical practice and challenged international safety standards. Now 93, she...
- discovered the link between fetal x-rays and childhood cancer
- discredited official research that grossly underestimates the effects of the Hiroshima blast
- demonstrated that workplace exposure to radiation is twenty times more dangerous than safety standards admit
- fought suppression of her work by government and industry
The Woman Who Knew Too Much recounts Stewart's long struggle as an isolated woman scientist battling the nuclear establishment. More than a biography, this important new book details the ways in which the nuclear establishment stonewalls threatening information. It lucidly explains scientific discoveries central to the controversy over nuclear waste disposal, safety standards, and compensation claims.
334 pages, 31 b&w photos, ISBN 0-472-11107-8
Radiation: how safe is safe?
The A-bomb database -- a record of the health and mortality of the survivors of the Hiroshima and Nagasaki atomic bombs -- is considered the gold standard when assessing the health risks of radiation. Alice Stewart, however, has spent much of her career arguing that it cannot be trusted. Her latest research, published this week in the International Journal of Epidemiology (vol 29, no 4), strengthens that argument.
The database is used to compare the mortality rates of A-bomb survivors with other Japanese citizens born at the same time. The results have always been the same: people exposed to low doses do not have a higher than average risk of cancer.
Stewart says these conclusions are unreliable because the bomb survivors are not truly representative of Japanese society.
In her latest paper, she focuses on the 2600 people who suffered severe radiation injuries even though most received only a small radiation dose. In particular, she wanted to compare their incidence of cancers and other diseases with that of around 60 000 low-dose survivors who did not suffer from serious injuries.
Stewart found the minority group had a much higher incidence of cancer and heart disease. She says these findings were reported to the European Parliament two years ago (see New Scientist, 28 February 1998, p 12) but that the assembly, curiously, decided not to make them public.
Stewart's detractors have pointed to a series of studies showing that certain survivors of the Hiroshima and Nagasaki bombs lived slightly longer than people who had not been exposed.
But research published in The Lancet (vol 356, p 303) at the end of last month casts doubt on these results. Researchers from the Radiation Effects Research Foundation in Hiroshima examined the effects of radiation on the 120,000 A-bomb survivors and found that people who received low doses did not live longer than average.
From New Scientist magazine, 05 August 2000.
[NB98.09-19] UK: Radioactive dust particles in the air could be responsible for `unusually high numbers of childhood leukaemia cases near nuclear establishments'. According to a study by Chris Busby, an independent scientist acting for the European Committee on Radiation Risk, plutonium particles could be suspended in the air by electrostatic action, and might also be repelled from earthed monitoring equipment, avoiding detection. (Independent, 26 February, p6) Separately, a British epidemiologist has suggested that the health of the young and old is more susceptible to damage from radiation than previously thought. Alice Stewart based her analysis on survivors of the Hiroshima and Nagasaki bombings. (New Scientist, 28 February, p12)
European Parliament hears criticisms of radiation protection standards,
but don't publish findings
See Summary of Dr.Stewart's Presentation (below)
SURVEY AND EVALUATION OF CRITICISM OF BASIC SAFETY STANDARDS FOR THE PROTECTION OF WORKERS AND THE PUBLIC AGAINST IONISING RADIATION
Brussels, LEO 5-E-2
Thursday, 5 February 1998
- 09,00-09.10 Opening of the Workshop
- 09.00 09.05 Welcome address. Paul Lannoy MEP, Vice Chairman Environment Committee EP, and rapporteur for the EP on Radiation Standards
- 09.05-09,10 Opening address. Scope of the Workshop. R.J. Holdsworth, Head of the STOA Unit
- 09.10-10.45 Session 1 The current debate on basic safety standards for the protection of workers and the public against ionising radiation Chair: Paul Lannoy, MEP
- 09.10-09.25 The Euratom Basic Safety Standards, radiological protection of workers and the general public. S. Kaiser, European Commission, DGXI
- 0925-09.40 A-bomb Survivors. Reassessment of the Radiation Hazard. A. Stewart, The University of Birmingham, UK
- 09.40-09.47 Value judgements in the radiation protection Philosophy Time for changes? Jovan Jovanovich, University of Manitoba, Canada
- 0947-09.55 The Sievert is not a scientific unit David Sumner, Moss Park, Ravenstone, Whithorn Scotland
- 09.55-1045 Discussion
- 10.45-12.30 Session 2 ionising radiation and biological systems Chair: Antonios Trakatellis, MEP
- 1O 45-11 00 Averaging errors in the perception of health risks from internal radioisotopes with specific emphasis on mutagenic enhancement due to 2nd Event effects caused by sequentially decaying man-made fission-product beta-emitters. C. Busby, Green Audit, United Kingdom
- 11.00-11.15 The European Late Effects Project Group (EULEP). Scientific Activities in the Field of Radiation Protection. J.W. Hopewell, Normal Tissue Radiobiology Group, Research Institute (University of Oxford), United Kingdom
- 11.15-11.22 Delayed effects of low dose irradiation; implications for protection Carmel Mothersill and Colin Seymour, Department of Physics, Dublin Institute of Technology, Ireland
- 11.22-1128 Evidences of the Impact on Health by Normal Operation of Nuclear Facilities. Heiko Ziggell, Physikerburo Bremen, Germany
- 11.28-11.35 Nuclear waste reprocessing plants and leukaemia in young persons: A review. Jean-Francois Viel, Faculty of Medicine, Besancon, France
- 1135-12,30 Discussion
- Break for lunch
- 14.30-16.00 Session 3 Risk assessment Chair: Nuala Ahern, MEP
- 14.30-14.45 The Concept of Equivalent Dose and Dose Limits-Urgent Improvements. H, Kuni, Phillips-Universitaet Marburg, Germany
- 14.45-1500 Radiation risk assessments, protection policies, and procedures of the International Commission or Radiological Protection. J. Valentin, Swedish Radiation Protection Institute, & Scientific Secretary, ICRP
- 1500-15 07 Cost/benefit assessment in the prevention of low radiation exposures. Klaus Becker, RSH, Berlin
- 15 07-15 1 5 Radiation & General Risks Assessments by Chernobyl `86 Radiation Surveillance Servicemen. Sergii Mirnyi, Central European University, Hungary
- 15.15-16.00 Discussion
- 16.00-17.30 Session 4 Legitimation, validation and implementation Chair: Paul Lannoye, MEP
- 16.00-16.15 Some problems of radiological protection 0f public in the situations of radioactive environmental contamination R.M. Alexakhin, Russian Institute of Agricultural Radiology and Agroecology, Obninsk, Russia
- 16.15-16.30 Limitations of the ICRP Recommendations for Worker and Public Protection from Ionising Radiation. R. Bertell, International Institute of Concern for Public Health, Canada
- 16.30-16.38 Radiation Monitoring in Practice and its Relation to Radiation Protection Limits. 0. Dietze, Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
- 16.38-16.45 Public debate on deficiency of standards. I Uray, Institute of Nuclear Research of the Hungarian Academy of Sciences, Hungary
- 1645-17.25 Discussion
- 1725-1730 Concluding remarks, Paul Lannoye MEP
The Report of this Workshop remains unpublished
(as at 22nd November 1998).
For further information contact the head of the STOA Unit, Dick Holdsworth.
Directorate-General for Research
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Summary of Dr.Stewart's Presentation at STOA 1998:
(From http://members.nbci.com/osseticamb/effettirad.html)In her invited paper contributed to the Workshop, Alice Stewart [Stewart 1998] questions the risk estimated for cancer effects of radiation which are based on the Life Span Study cohort of the a-bomb survivors. According to Stewart both from the Oxford Survey of childhood cancers, and from recent surveys of nuclear workers at Handford and Oak Ridge, have come risk estimates for radiation induced cancers that are much higher than the ones based on the LSS cohort of A-bomb survivors. Therefore, there is a need to clarify whether the LSS cohort is a homogeneous population, or, alternatively, whether the persons who had survived acute effects of the bombing constitute a special radiosensitive subgroup of this study cohort.
The main results of the statistical analysis of the LSS data by Professor Stewart provide evidence that:
- Cancer was not the only late effect of the A-bomb radiation; some of the high dose survivors had remained at high risk of dying from non-stochastic effects, such as irreversible damage to the immune system.
- Exposure before 10 and after 55 years of age carried an exceptionally high cancer risk.
- Differences between survivors with and without acute injuries were largely the result of persons who (by virtue of their age in 1945) were at high risk of dying before the LSS cohort of five years survivors was assembled. As a result of the early deaths there was no question of the study cohort being a normal unselected population.
Focusing attention on survivors who either denied all injuries or claimed at least two injuries, Dr. Stewart maintains that her analysis minimised the effects of faulty reporting and made possible to see that persons who survived non-stochastic effects of the radiation constituted a special subgroup of the LSS cohort. Analysing new LSS data, it was possible to recognise that levels of radio-sensitivity were much higher at the beginning and end of the life span than during the intervening period, and that it was only among survivors who claimed several injuries that leukaemia deaths were exceptionally common.
Given an association between leukaemia and tissue destructive effects of ionising radiation, it was possible that the different findings for leukaemia in A-bomb data stemmed from early effects of all high dose exposures. The loss of immunological competence would explain why the extra radiogenic leukaemias had short latent periods and lymphocytopenia would explain the absence of lymphatic leukaemias among these cases.
How to test the above hypothesis is not immediately obvious, but it would explain why, in A-bomb data, the association between radiation and leukaemia is so selective.
Dr. Stewart remarked that the A-bomb survivors are not representative of the people who died since the levels of radio-sensitivity are controlled by the immune system, which also controls infections. The radio-sensitive people were removed from the population from the destructive effects of the bomb. That is why we are currently working on a basis which only provides for extremely resistant people. If the population was composed of young men, this condition would represent extreme-radio-resistance, which is in fact exactly what happened in the A-bomb survivor study.
Having said that, the A-bomb survivor data are not a good data basis, and are particularly misleading with regard to age. However, Dr. Stewart remarked that they can be used to discover the factors that influence the radio-sensitivity of people.
Commenting on the usefulness of the Hiroshima and Nagasaki data during the ensuing discussion, Klaus Becker, in agreement with Alice Stewart, added that these data are characterised by very high dose rates, large uncertainties on the dose estimates, complicated by dominating heat and pressure injuries, emotional stress, breakdown of social and medical services and a totally destroyed city. These factors amount to a situation, which is hardly comparable to the normal situation in which we live and work. So the linear extrapolation of data from Hiroshima and Nagasaki maybe as dangerous, as the radon situation, where there has been a linear extrapolation down to zero in homes.
" . . . that the population is uniformly radiation sensitive. This is not sustainable. The Hiroshima and Nagasaki studies did not begin until 1950 and data exclude people who died in the first few years after the bomb.
These studies are really based on a `radiation resistant' population. Alice Stewart (STOA 1998) has also shown that even among the Japanese survivors who are included in the study children and those over 55 years of age carry an exceptionally high cancer risk. This finding renders all the more unacceptable the assumption made by DETR's consultants WS Atkins and Electrowatt (DETR/RAS/98.004 p 8) that they should calculate Clearance Levels on the basis of doses to adults "because most of the population of the UK are of adult age." Some of the Clearance scenarios would put children at far higher risk of ingesting radioisotopes. Notable in this respect are scenarios leading to inclusion of transuranic isotopes in smelter slag and thence into garden fertilisers and playground surfaces, and clearance of contaminated soil. What kind of society is it that ignores the greater susceptibility of its children and then puts them at disproportionately higher risk of incurring those doses?
Longevity of atomic-bomb survivors -- Lancet 2000; 356: 303-307
John B Cologne, Dale L Preston
Department of Statistics, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan (J B Cologne PhD, D L Preston PhD)
Correspondence to: Dr John B Cologne (e-mail: email@example.com)
Background Conflicting claims have been made regarding biological and health consequences of exposure to low doses of radiation. Studies have suggested that certain low-dose exposed atomic-bomb survivors live longer than their peers. Earlier studies in other radiation-exposed populations demonstrated life shortening from mortality from cancer but lacked dosimetry and relied on comparison groups which may introduce bias because of lack of comparability. We have re-examined the effect of radiation on life expectancy in one cohort of survivors of the atomic bombings of Hiroshima and Nagasaki, Japan.
Methods We did a prospective cohort study of 120 321 survivors. The study encompasses 45 years of mortality follow-up with radiation-dose estimates available for most cohort members. We calculated relative mortality rates and survival distribution using internal comparison (cohort-based estimation of background mortality).
Findings Median life expectancy decreased with increasing radiation dose at a rate of about 1·3 years per Gy, but declined more rapidly at high doses. Median loss of life among cohort members with estimated doses below 1 Gy was about 2 months, but among the small number of cohort members with estimated doses of 1 Gy or more it was 2·6 years. Median loss of life among all individuals with greater-than-zero dose estimates was about 4 months.
Interpretation These results are important in light of the recent finding that radiation significantly increases mortality rates for causes other than cancer. The results do not support claims that survivors exposed to certain doses of radiation live longer than comparable unexposed individuals. Because the cohort was intentionally constructed to contain a higher proportion of high-dose atomic-bomb survivors, average loss of life among all exposed atomic-bomb survivors would be less than the 4 months found for the study cohort.
Lancet 2000; 356: 303-07