NUCLEAR POWER-PLANT DISASTERS

NUCLEAR POWER-PLANT DISASTERS

32 APPROXIMATE NUMBERS OF ACUTE AND LATE DEATHS AFTER A NUCLEAR REACTOR ACCIDENT, BASED ON GERMAN STUDY’ Public Health NUCLEAR POWER-PLANT DISASTERS ...

552KB Sizes 14 Downloads 299 Views

32 APPROXIMATE NUMBERS OF ACUTE AND LATE DEATHS AFTER A NUCLEAR REACTOR ACCIDENT, BASED ON GERMAN STUDY’

Public Health NUCLEAR POWER-PLANT DISASTERS Health

and Need for Medical Care*

Consequences

Subsequent

K. R. TROTT

Radiobiological Institute, University of Munich; and Institute of Biology, Gesellschaft für Strahlen-und-Umweltforschung, Neuherberg, West Germany A NUCLEAR power-plant disaster may be said to occur when a large proportion of the radioactivity within a reactor gets into the environment. About 99% of the several billion Ci of radioactive fission products is trapped in the crystalline structure of the uranium in the fuel rods.I,2 The only way this radioactivity can escape is if the reactor core melts after failure of all the cooling systems. Even after the reactor is switched off, heat is still produced by radioactive decay of the shortlived fission products. A core melt-down has not yet but the Three Mile happened anywhere in the western world, Island accident came very close to it.3 AMERICAN AND GERMAN PREDICTIONS

Americanand German2

reactor safety studies have tried to the question of how often a core melt-down accident is likely to occur and what its consequences would be. Despite technical and geographical differences, the results of both studies were similar: answer

1.-A core melt-down may occur in a light water reactor once every 10 000 years of operation. This means that within the next 10 years there is likely to be a core melt-down accident somewhere. 2.-The degree of radioactive damage will depend upon the timescale of the accident and how quickly the radioactivity penetrates into the environment. This may take hours or days, but the sooner the reactor defences fail, the greater will be the radiation dose to people in the surrounding area. The radiation may cause early disease and death from destruction of the bone-marrow, or late disease and death from cancer or genetic mutation. The German study predicted that there would be about 100 000 cancer deaths in the worst accident which could occur if several unfavourable conditions coincided. This is only likely to happen once in a billion years (see table). A less serious accident likely to occur once in a million years could cause over 50 000 cancer cases. Any core melt-down accident could produce an enormous amount of late damage to man. Genetic damage could affect over 10 000 children born in the next two generations after a core melt-down of the magnitude likely to occur once in a million years. RISKS AND

CONSEQUENCES

The linear dose/response relationship between radiation dose and cancer risk used in the German study, in accordance with the recommendations of the International Committee on Radiological Protection (ICRP),4 indicates that there would be the same number of cancer cases if either a million people were irradiated with a dose of 1 rad, or if five thousand people wereirradiated with 200 rad (resulting in a hundred cancer deaths in both cases). The risk to an individual from 200 rad is very different from the risk resulting from 1 rad. This fact is important since 90% of all cancer fatalities after *Based on a Special University lecture sponsored by the Board of Studies in Radiation Biology, University of London, at the Middlesex Hospital Medical

School, February 25,

1981.

core

melt-down accidents have been calculated

to occur

in

subjects who received radiation doses of less than 5 rad-less than the lifetime dose from natural background radiation. The majority of cancer cases would therefore occur in people considerable distance from the site of the accident. to the German study more than 50% of cases would occur outside that country. Thus, cancer as a consequence of nuclear power plant disasters would be an international problem. In any core melt-down accident, as defined above, the total number of fatal cancer cases would exceed several thousand, rising to over 100 000 where there had been an early, massive release of radiation into the environment. However, for those living close to a nuclear power-plant, cancer would not be the major hazard. Near the plant the incidence of cancer at any time after an accident would not rise significantly above that resulting from natural background radiation. 90% of all cancer cases would be caused by doses smaller than those from natural background radiation. The emergency procedures envisaged in most countries would have no significant effect on the total number of cancers or the genetic risk arising from a serious accident. The only major risk to an individual after a nuclear accident would be from the acute at a

According

radiation syndrome. To estimate the number of acute fatalities after an accident the between the risk of death from acute radiation illness and the total body radiation dose must be defined. For cancer induction there is a proportionately greater risk with increasing radiation dose, but for the acute consequences of radiation exposure there is a threshold below which no severe damage would occur (about 100 rad). The numerous animal experiments on the relationship between radiation dose and death from acute radiation illness show an S-shaped dose/response curve. Fortunately, human experience is scarce. Most textbooks of radiobiology reproduce the same curve first published in a book on the effects of nuclear weapons (fig. 1).5 However, recently published data disagree with this curve, and it may at best be described as an "educated guess".

relationship

VICTIMS AND CANCER

After a nuclear disaster, radiation victims are likely to receive proper medical treatment during the subsequent six weeks. For experienced oncologists and haematologists it should not be difficult to save the life of every healthy adult or child who receives a radiation dose of up to 500 rad, even without transfusion of compatible bone-marrow stem cells. I believe that the concept of dose/response curves for acute radiation illness is unsuitable for describing what would happen after an accident. The probability of survival depends upon factors unrelated to the radiation dose, such as general health, infection, treatment with drugs for specific diseases, and pregnancy. An old person with severe chronic bronchitis and emphysema has a much lower probability of survival after 200 rad than does a healthy person after 500 rad. I have defined a dose/response curve to calculate the possible number of acute fatalities, but am aware that owing to the

33

Dose to bone

marrow

Fig. I-Dose/response curve for acute radiation mortality in man5 and mortality data from different irradiated groups. L=lymphoma patients receiving single dose radiotherapy. M=total body irradiation from fall-out on the Marshallese islands.’ 0 =Japanese fishermen.8 TBI = leukaemia patients irradiated before bone-marrow grafting: deaths from interstitial pneumonia. ’ ’ 4 A=Algerian radiation accident victims. I0

distance from accident

Fig. 3-Individual risk of death from cancer or the syndrome versus distance from site of accident.2 of the concept these numbers are speculative. The German study2 used a dose/response curve which tried to account for the fact that a sizeable proportion of the population is more sensitive than average to radiationinduced changes in white blood cell and platelet counts. Thus, the curve they used is flatter than that of the American study’ (fig. 2)-. From the German curve I calculate (making certain assumptions about emergency measures) that up to 10 000 people might get acute radiation illness after an accident of maximum credible size. The differences in the estimated results between cancer risk and acute radiation illness (see table) indicate what could be done to decrease the number of fatalities and the risk to the individual. Whereas cancer risk decreases slowly with distance from the accident (fig. 3), acute radiation illness is confined to a small area near the reactor, not exceeding an 8 mile (13 km) radius. In over 99% of all core melt-down accidents, acute hazards would only occur at a distance of less than 5 miles.2 Acute radiation illness would be the major risk for those living close to a nuclear power plant. In my estimation the number of cancer victims would depend solely upon the total amount of radioactivity released from the damaged reactor and would not be markedly influenced by weather conditions or the emergency measures

inadequacy

Mortohty

acute

radiation

taken. The number of early radiation illness victims would be determined by factors such as wind, rain, and how people affected by the disaster reacted and behaved. The most important factor, however, would be the quality of the emergency measures taken. EMERGENCY MEASURES

Emergency plans for nuclear power-plants in all European countries recommend evacuation of the population likely to radiation dose of either 50 or 100 rad or more. I regard this recommendation as utterly academic and unrealistic. It implies that after an accident the amount of radioactivity released into the environment and the direction, speed, and precipitation of the wind must be calculated. The resultant radiation doses must be determined from the various exposure pathways, and finally a decision made as to what should be done. However, in any catastrophic situation the reaction must be as fast as possible, and to start to think and plan only after the release of radioactivity would be a waste of precious time. Between the moment the engineers in the reactor know for certain that a core melt-down is inevitable, and the actual release of radioactivity, there may be a lapse of hours or even days-time enough in most cases to evacuate those who might be in danger. Experience has shown that it is possible to evacuate everybody living downwind to a distance of 3 miles within as little as 2 hours, provided that the evacuation has been planned beforehand.

receive

a

Only in the extremely rare event of a very early, massive release of radioactivity would events proceed so fast that people could not be evacuated in time. In this case, people would be advised to stay at home, preferably in a basement, and shut the windows. Most houses could provide a satisfactory shelter for several hours until evacuation started after the radioactive cloud passed. Nevertheless, these people would probably be badly contaminated with radioactivity and irradiated with an unknown dose of gamma rays. They would have to be decontaminated as soon as they left the area and might have to be treated for their radiation illness. MEDICAL CARE

Fig. 2-Dose according

response to reactor

curves

for

acute

radiation

safety studies.’1

mortality in

man

To plan medical care for these people, it is necessary to know how many people to expect, how severely they would be contaminated, what their radiation dose would be, how to calculate this dose for an individual, and how large the

34

variability of radiation

doses would be among victims from the same area. -In any such case in Germany, several thousand people (up to 40 000) would have to be dealt with. As long as evacuation could be performed before the release of radioactivity, there would be no contamination and no radiation exposure to worry about, but if evacuation could only be carried out after the cloud had passed, contamination would be a major problem. The simplest and best method of decontamination is to change clothes. Showers, which are recommended in most emergency plans, do more harm than good. The more clothes worn before exposure to radioactivity, the easier is the subsequent decontamination. People in the same area may have received very different radiation doses. Therefore the doctors would have to rely on their judgment in order to decide who would need medical care at a later time. However, since there is an interval of several weeks between irradiation and the onset of acute radiation illness there would be no urgency. Doctors could first concentrate on those patients who were obviously ill-mostly from pre-existing diseases not related to the accident. Simple tests, in particular the white blood cell count and differential, could quickly identify those who would develop radiation illness 3 to 4 weeks after the accident. The most reliable sign is the total lymphocyte count (fig. 4).

inhaled. Yet, stable iodine itself has side-effects. They are rare, but so are the carcinogenic side-effects of radioactive iodine. 13 Especially in countries where the diet is deficient in iodinel4 many people have autonomous adenomas in their enlarged thyroid glands which avidly take up any available iodine in order, to produce thyroid hormone. This can lead to attacks of hyperthyroidism some time later. The risk of this side-effect of stable iodine can be estimated from the incidence of hyperthyroidism in Tasmania after the iodination of bread. Hyperthyroidism developed in about 0’ 1% of the total adult population, in excess of the previous incidence.15 To assess the value of stable iodine in decreasing thyroid radiation doses the risk of acute hyperthyroidism must be balanced against the risk of late thyroid cancer and hypothyroidism. Even in Germany, where the diet is very deficient in iodine, significant gain from the use of stable iodine after a nuclear accident could only be expected if the projected uptake of radioactive iodine were several times the amount given for diagnostic purposes, i.e., in very serious accidents where other problems arising from whole body irradiation are so dominant that the prevention of latent hypothyroidism and thyroid cancer is of minor importance. I do not believe that stable iodine would be of great value in nuclear accidents. CONCLUSIONS AND RECOMMENDATIONS

To summarise the conclusions of the reactor safety studies it should be stated that any core melt-down acident in a nuclear power station would destroy property, be very costly, threaten the lives of many people who would have to be evacuated, and lead to many additional cancer cases during the next 50 years. Seen in the perspective of more frequent disasters in industry and energy production, the consequences of a core melt-down are not outstanding. A person living close to a nuclear power station has an almost 100% chance of surviving any such accident if he behaves in accordance with well-planned instructions. Only those who away in panic are in acute danger. Therefore, it is essential that people who live near nuclear power stations should be well-informed about the probable circumstances of a major accident and told what they can do for their own protection. The authorities should plan for the rapid evacuation of people within a radius of 3 to 5 miles, which in most cases should be feasible within a few hours, before radioactivity escapes from the power station. Other immediate measures are not necessary for the saving of human lives. Decontamination may pose problems if evacuation cannot be carried out before the release of radioactivity-yet in most instances the problem could be adequately dealt with by changing clothes and by washing the face and hands. Medical treatment of those severely irradiated is identical with the treatment of other forms of bone-marrow depletion illness. Whereas adequate emergency measures would be sufficient to reduce acute fatalities to nearly zero, the total number of late cancer fatalities and hereditary diseases in the next two generations would not be markedly influenced by these measures since the effects would mostly occur at distances far from the reactor, and as a result of radiation doses which are small compared with those from natural and other man-made run

DAYS after total body irradiation in relation to the absolute number of lymphocytes/0 in the peripheral blood.I

Fig. 4-Prognosis

During the first 2 weeks only those patients who had received large doses of radiation would need to be in hospital. It is, however, extremely unlikely that anyone would receive a radiation dose of over 600 rad, unless he had stayed near the reactor

in the open for many hours and refused

early

evacuation.22 THYROID CANCER

The radioactive plume would contain large quantities of various radioactive isotopes of iodine which could be inhaled and accumulate in the thyroid gland and give radiation doses considerably higher than those to other organs. After a core melt-down accident, 1311 and other isotopes of iodine might be inhaled in quantities greater than those given in nuclear medicine for diagnostic purposes, and approaching doses given for the treatment of hyperthyroidism. The result might be cancer of the thyroid or hypothyroidism. Stable iodine, taken before exposure, can prevent 99% of the uptake of radioactive iodine into the thyroid gland.12 Therefore, most countries recommend the distribution of stable iodine if equivalent radioactive doses of about 10% of the amount given to patients for diagnostic purposes are likely to be

sources. REFERENCES 1 Reactor

study -

an assessment

of accident risks in US commercial power plants. 1400

(NUREG-75/014). Washington: US Nuclear Regulatory Commission, 1975. 2. Deutsche Risikostudie Kernkraftwerke. Köln Verlag TUV Rheinland, 1979 3. Investigation into the March 28, 1979 Three Mile Island accident by Office of Inspection and Enforcement. NUREG - 0600. Washington: US Nuclear Regulatory Commission, 1979. 4. Recommendations ofthe International Commission on Radiological Protection. ICRP publication 26 Oxford: Pergamon Press, 1977.

35

Round the World From Our

Correspondents

Bangladesh A TRANSFER OF PHARMACEUTICAL TECHNOLOGY

IN this country where the average income is$70 a year, nearly three-quarters of the medicines on the market would be classed by British and American authorities as having little or no therapeutic value. Yet they are promoted in such a way that people sometimes go without food to buy them. Self prescription is common, and drugs can be freely obtained across the counter. Most of the medicines are made in Bangladesh by multinational companies. The question of how to get good and cheap medicines to the people has been much discussed at Gonoshasthaya Kendra, a project which began in 1972 with the aim of providing primary and preventive health care, and which later spread its activities to community development work. What was needed, they decided, was a source of low-cost, high-quality essential drugs, coupled with a means of responsible marketing. With the aid of NOVIB (a Dutch voluntary agency), Oxfam, Christian Aid, and others, they built a factory, bought equipment, and secured training for local managers (total cost$4’ 11 million); and, in May, the first batches of the first two drugs emerged-paracetamol (acetaminophen) and ampicillin. Gonoshasthaya Kendra Pharmaceuticals hope eventually to supply 15-20% of the Bangladesh market in essential drugs, at prices onethird to half lower than those of existing products. One problem yet to be solved is how to hand on the benefits of these drugs to consumers without profiteering by middlemen. Gonoshasthaya Kendra see this project as something more than the building and running of a factory. Rather, it is an instance of genuine transfer of technology (the multinationals have always brought in complete blueprints which provide no opportunity for training of local manpower). They hope also to show how industrialisation can be controlled by, and work to the benefit of, the mass of the people.

North Yemen DISTRIBUTION OF DRUG SAMPLES

THE Yemen Arab Republic (North Yemen) has no oil wealth, but it has prospered from its wealthy neighbours. Remittances from workers outside the country have fuelled a consumer boom. Nonetheless, the country is chronically underdeveloped, particularly in terms of health care. Yemen has among the highest rates of infant mortality and lowest life expectancy in the world.

S, ed. The effects of nuclear weapons. Washington: US Atomic Energy Commission, 1962. 6. Langham WH, ed. Radiobiological factors in manned space flight. Washington: US National Academy of Sciences, National Research Council, 1967. 7. Bond VP, Fliedner TM, Archambeau JO. Mammalian radiation lethality. New York: Academic Press, 1965. 8. Kumatori T, Ishihara T, Hirashima K, Sugiyama H, Ishii S, Mijoshi K. Follow-up studies over 25-year period on the Japanese fishermen exposed to radioactive fall-out in 1954. In: Hübner KF, Fry SA, eds. The medical basis for radiation accident preparedness. New York: Elsevier, 1980. 9. Thomas ED, et al. One hundred patients with acute leukaemia treated by chemotherapy, total body irradiation and allogenic marrow transplantation. Blood 1979; 49: 511 10. Jammet H, Gongora R, Pouillard P, LeGô R, Parmentier N. The Algerian accident 1978: four cases of protracted whole body irradiation. In: Hübner KF, Fry SA, eds. The medical basis for radiation accident preparedness. New York: Elsevier, 1980. 5. Glasstone

11.

EL. Care of patients involved in radiation accidents: recent advances. In: Strahlenschutz in Forschung und Praxis, Vol XI. Stuttgart: Thieme Verlag, 1971. 12. Protection of the thyroid gland in the event of release of radioiodine. Report no. 55. NCRP, 1977 13. Holm LE, Lundell G, Walinder G. Incidence of malignant thyroid tumors in humans after exposure to diagnostic doses of iodine-131, retrospectivestudy. J Nat Canc Inst

Saenger

1980; 64: 1055 14. Habermann J, et al. Alimentärer Jodmangel in der Bundesrepublik Deutschland. Dtsch Med Wschr 1975; 100: 1937. 15. Stewart JC, Vidor GI. Thyrotoxicosis induced by iodine contamination of food - a common unrecognised condition? Br Med J 1976; i: 372-74.

There is no local drug production and drugs are imported mainly from West Germany, Switzerland, and Britain. The distribution of samples is the dominant feature of drug promotion. Yemen has some apparently unique legislation on samples. The Ministry of Health stipulates that companies must hand over to them 20% of all the drug samples they are authorised to import. These samples are earmarked "for the stores of the General Office of Pharmaceuticals and Medical Supply in the Ministry of Health, to support government drug services".’There are virtually no restrictions on sampling. Sales representatives have been stopped from visiting public health service doctors in the mornings. But samples are handed over to doctors outside the clinics, or while they are engaged in private practice during the afternoons. The sale of drug samples is technically illegal, but the ban is very hard to enforce. Patients are sold products marked "free sample", and these are stocked on the shelves of even the remotest village drug stores. 1. 4th Annual

Report on the Activities of the Supreme Board for Medicines and Medical Equipment during 1979 (translated).

In

England Now

Last April 1 the Executive Group decided to enter into the spirit of the day. "It’s dreadful," I said loudly, as we queued for lunch. "Decimalisation of annual leave. What will they think of next?" "It’s the Common Market," replied the Secretary. "Another directive from Brussels." "We will all lose by it," declared the Treasurer with finality. The lady behind the counter stopped serving immediately. "What does it all mean?" she asked. "Well," I replied, "from now on, annual leave has to be calculated at 0-33 days per 10 days worked." "But to be rounded down," said the Secretary. "If, for example, it comes to 12 - 8 days, we will lose the 0 - 8 days." "It’s the Continental Sunday which is the worst," I continued. "Indeed," agreed the Secretary. "Over there, they treat Sunday like a holiday. So from now on, every tenth Sunday here will be regarded as one day’s annual leave." "We will all lose by it," declared the Treasurer sadly. We left to eat our meal chuckling mightily. Two hours later we were trying to avert a "constructive withdrawal of labour". Our explanations sounded painfully weak. Only a solemn promise of a return to the status quo allowed normal service to resume. We are now in correspondence with the official representative. Who, I thought, were the April fools? *

*

*

I cannot remember when I saw my friend Giles so despondent. Not even when the winks, nudges, and hints of his senior colleague turned out to betoken not a forthcoming merit award, but simply an invitation to join the Masons. His present depression stems from the possession of an antique writing desk, the gift of a member of that fast disappearing species,

grateful patient. It was a delightful piece with its decorative inlays, brass handles, and general patina of old age. Its attraction was enhanced by the intricately worked legs which ended in small, beautifully carved, lion heads. Unfortunately, it had a wobble. A the

search for a cabinet maker measuring up to Giles’s exacting standards proved fruitless. The fault remained untreated. One day, however, his quest was rewarded. Whilst on a domiciliary visit to a small market town, he chanced upon an old-fashioned furniture repair shop. The ancient craftsman, his silvery hair, half-moon spectacles, and work-worn apron lightly covered in a dusting of sawdust, listened patiently to the problem. Yes, he said at last, he thought it could be solved. He would call in a few weeks’ time. And this he did. As he slowly unpacked his tools from an old leather bag, Giles thought it best to leave him in peace. He left the room almost on tiptoe. When he returned that evening, the desk stood firm and square, without the slightest trace of movement. Beside it, neatly lined in a row, were the four lion heads. They had been sawn off.