7 February 1997       Doc. 7751

ADOC7751

OPINION1

on the health effects of the Chernobyl accident

(Rapporteur: Mr Martti TIURI,

Finland, European Democratic Group)

_____

Introduction

1.       The current report of the Social, Health and Family Affairs Committee, which follows a visit paid by its Rapporteur in Ukraine and in Belarus in early 1996, underlines two different important health consequences of the accident, generally accepted by specialists: a) increase in the incidence of childhood thyroid cancer and b) psychological effects (not due to radiation) such as neuropsychological disorders, digestive illnesses, cardiovascular disorders or chronic bronchitis. It also considers leukemia and other cancers and diseases, warning that information about them must be treated with caution, in particular information about the rate of leukemia.

2.       Your Rapporteur for opinion on behalf of the Committee on Science and Technology feels it necessary to expand the analysis of today's different - and frequently contradictory - views of the health effects of the Chernobyl accident by basing it on the scientific knowledge of the health effects of radiation.

3.       The health effects of radiation have been carefully studied and determined by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and by the World Health Organisation (WHO). The resulting data is in common use in all cases concerning the effects of radio active radiation.

4.       The health effects of the Chernobyl accident have been studied by the International Advisory Committee, which in 1991 published its findings in a report: "The International Chernobyl Project". WHO published in 1995 the report: "Health consequences of the Chernobyl accident", describing results of several thorough studies, some of which are still going on. The Nuclear Energy Agency (NEA) of OECD has published a report: "Chernobyl, ten years on: the radiological and health Impact. Your Rapporteur has used these documents as a basis in considering the health effects of the Chernobyl accident.

The scientific knowledge of the health effects of radiation

5.       When considering the health effects of the Chernobyl accident it is important to take into account the present scientific knowledge about the effects of radiation. In addition it must be remembered that everybody is continuously exposed to natural background radiation caused by cosmic rays from space and from natural radio active materials in the soil and in the human body.

6.       According to the International Chernobyl Project individual lifetime radiation doses in the areas contaminated by the accident in the Ukraina, Belarus and Russia vary from low values to several hundred mSv (mSv, millisievert is a measure for radiation exposure). On the other hand lifetime radiation doses for every individual due to natural radiation vary from about 100 mSv to several hundred mSv.

7.       Hence, natural radiation doses are of the same order of magnitude as doses from the accident. Outside the contaminated areas of the Ukraine, Belarus and Russia natural radiation is much stronger than the radiation due to the accident. For example in Finland the lifetime dose from natural radiation is on average 260 mSv. The dose from the Chernobyl accident will be 1-2 mSv inspite of relatively heavy fallout.

8.       Our understanding of the health effects caused by radiation is based mainly on studies of the survivors of atomic bombs in Japan. The only detected long-term health effect has been an increase in cancer deaths. Hereditary effects have not been detected among the descendants of the survivors. Atomic bombs did not produce radioactive iodine and hence have not given information about thyroid cancer.

9.       According to UNSCEAR and WHO the probability of cancer death due to radiation is directly related to doses between 0-1000 mSv. If an individual gets a radiation dose of 200 mSv it causes a probability of one per cent that he will die of cancer during the following 50-70 years. For other doses the probability is related to the dose rate. Correspondingly if everyone in a population of one hundred thousand gets a radiation dose of 200 mSv, it can be expected that one per cent of them or 1000 persons will later die of cancer due to this radiation dose.

10.       Cancer is a common disease. In industrialised countries about 20 per cent of all deaths are caused by cancer indicating that the probability of an individual to die of cancer is 20 per cent. A further radiation dose of 200 mSv increases it to 21%. However, death rates of cancer vary widely from country to country. They are also usually higher in cities. Typically the rate of cancer deaths varies from 15 to 25 per cent.

The health effects of the Chernobyl accident

a.        The increase of childhood thyroid cancer

11.       The increase of childhood thyroid cancer seems to be the major radiological effect of the accident. The international Advisory Committee predicted in its report in 1991 that thyroid cancers would be detected in the future. The fact that they have occurred so soon and so strongly has to a certain degree been suprising.

12.       Thyroid cancer is a very rare disease. According to WHO there is normally about one case per year per one million children. Now in the worst contaminated areas some 10-35 cases per one million children have been detected giving a clear proof that the cancer of these children is caused by radiation.

13.       Thyroid cancer can be treated by surgery, but continuous medication is needed. For the time being some 600 childhood thyroid cancer cases have been detected. Clinical experience indicates that 5-10 % of them will die of the cancer. So far, three deaths have been reported. Medical experts agree that thyroid cancer could have been avoided by iodine tablet treatment.

b.        The psychological effects

14.       The psychological effects of the Chernobyl accident belong to the second generally admitted category of health-related consequences. Significant increases have been recorded in endocrine diseases, mental disorders and diseases of the nervous system, sensory organs, and digestive and genito-urinary systems. According to WHO, while present evidence does not suggest that these diseases are radiation-induced, it is possible that such problems resulted from the considerable stress caused by the accident.

15.       People living in the contaminated areas have several reasons for psychological stresses causing symptoms as listed in the report. The main reason is that the radiation dose limits requiring evacuation were too low and it was not possible to carry out the evacuation plans. About 270,000 people continue to live in contaminated areas ("strict control zones"), from which evacuation was meant to be compulsory. Many of them are in continuous fear of becoming ill due to the radiation. Things are made worse by some local medical doctors who tell people that their symptoms are caused by radiation.

16.       Secrecy about the accident, lack of knowledge about the effects of radiation and the political and socioeconomic changes occurring in the USSR during and after the Chernobyl accident have added to the anxiety.

17.       The International Chernobyl Project concludes that "the protective measures taken or planned for the longer term, albeit well intentioned, generally exceed what would have been strictly necessary from a radiological protection viewpoint. The relocation and foodstuff restrictions should have been less extensive." It is probable that in some cases the radiation effects avoided by evacuation are smaller than the health effects caused by relocation.

c.        Leukemia and other cancers

18.       There have been many claims about increase in leukemia and other cancers among people living in the contaminated areas. In many cases these results are based on inadequate statistics or the small number of cases where large variations can be expected according the laws of the theory of probability. As already stated before cancer death rates vary normally from 15 to 25 %. This means that in epidemiologigal studies the additional cancer deaths in a group must be over three % if they are to be detected against normal fluctuations. The corresponding radiation dose is around 600 mSv.

19.       The NEA report in 1995 estimated that during the first four years after the accident people living in the strict control zones had received a dose varying between 5-250 mSv. 1800 persons had received a dose exceeding 150 mSv. The average dose received by all people (270,000) living in strict control zones was 36 mSv.

20.       The lifetime radiation dose can be expected to be at its maximum 50 per cent higher than the dose during the first four years. Hence the average lifetime dose of 270,000 people still living in the strict control zones will be less than 60 mSv. The maximum dose is around 400 mSv.

21.       The dose of 400 mSv causes a probability of two % and the dose of 60 mSv a probability of 0.3 % of dying of cancer. Hence your Rapporteur for opinion agrees with NEA that it is unlikely that surveillance of the general population will reveal any significant increase in leukemia or other cancers. However, WHO is more cautious, stating that "since the peak in the incidence of blood disorders may occur more than 10 years after the accident, long-term studies of these diseases are needed".

22.       One exception might be the "liquidators" who worked in cleaning-up operations. Several hundreds of thousands of individuals participated in this work. The exact number of liquidators is not known and there is unsufficient data about the doses received by them. It is important to try to improve the information and continue the studies on the possible health effects.

23.       The Chernobyl accident produces important information on the behaviour of radioactive fallout from a nuclear accident in different types of soils and as a function of time. Hence studies of contamination rates and the radiation exposition of people must be continued for many years in the future.

Conclusions

24.       The only clearly detected health consequence caused by radiation from the Chernobyl accident is childhood thyroid cancer. In the areas worst contaminated 15-35 cases occur per year per one million children.

25.       Many diseases other than cancer have been claimed to be caused by radiation from the Chernobyl accident. However, according to present knowledge these diseases are psychological effects not directly related to radiation.

26.       The radiation due to the accident will cause extra cancer deaths corresponding to the doses people have received, but the number of deaths is probably too small to be detected, because normal fluctuations in cancer death rates are larger. The amount of deaths can only be estimated using the known radiation doses.

27.       The 60 mSv average radiation dose on the strict control zones causes according to the UNSCEAR data a probability of 0.3 % dying cancer in the future. Hence, among 270,000 people in the strict control zones about 800 extra deaths can be expected during 50 years due to Chernobyl fallout. In the same time about 50,000 cancer deaths are caused by other reasons (about 2,500 of which are due to natural radiation).

28.       800 extra deaths in 50 years corresponds to an increase in the yearly death rate of about 0.5 per cent (see Appendix). In countries outside the former Soviet Union the increase in the death rate due to the Chernobyl accident is negligible. For example in Finland a 1-2 mSv dose from the Chernobyl accident increases the death rate about 0.03 %. In comparison the increase of the death rate due to natural background radiation in Finland is 3 %.

29.       The Chernobyl accident has brought in the forefront the health consequences of nuclear accidents. As a result the construction of new nuclear power plants has stopped in many countries. The growing demand for electricity has been satisfied by building new fossil fuel power plants. This has increased fine particle pollution. In addition, carbon dioxide emissions have increased more rapidly as well as acid rain pollution.

30.       Lately it has been found in studies in the USA and Europe that fine-particle pollution caused by burning of fossil fuel in power stations, buses and cars increases the death rate several per cent. This indicates that fine-particle pollution can be more dangerous than the radioactive fallout in the strict control zones in the Ukraine, Belarus and Russia.

31.       It is important to inform people about the health effects of accidental radiation as well as natural background radiation. The safety aspects of western-type nuclear power stations as compared to Chernobyl-type nuclear power station must be also be considered. In addition, it must be remembered that fossil fuel energy can cause severe health effects. Information is needed to help people to make right decisions concerning power generation.

Appendix

Yearly death rates

All deaths       100 per cent

Deaths of cancer in Europe       15-25 per cent

Additions to yearly death rates due to different environmental reasons

(in the case of radiation the addition is caused by additional cancer, in the case of fine-particle pollution by additional cancer and cardiovascular diseases)

Chernobyl fallout, Strict control zones       0.5 per cent

Chernobyl fallout, Finland       0.03 per cent

Natural radiation, Europe on average       2 per cent

Natural radiation, Finland and Sweden on average       3 per cent

Fine-particle pollution (burning fossil fuels)       several per cent

Numbers are based on the data from WHO, UNSCEAR, NEA and on the reports:

WHO European Office: Update and revision of the air quality guidelines for Europe; Geneva 1995.

Dockery et al., The New England Journal of Medicine, Dec. 9 1993.

Amendment

to the draft resolution

on the health effects of the Chernobyl nuclear accident

(Doc. 7680)

      At the end of the paragraph 7 add the following new text:

"- improve the knowledge of people living in contaminated area of the health effects of nuclear radiation caused by an accident or by natural sources.

- encourage international cooperation in continuing studies of liquidators in order to gather more exact data about their radiation doses and possible health effects.

- encourage international cooperation in continuing studies of radioactive radiation in contaminated areas and monitor the radiation doses of the people living there.

- encourage continuous development and improvement of safety culture at all European nuclear power plants.

- inform people in all member countries of the health effects of accidental and natural radiation.

- inform people of the health and environmental problems of the various systems of energy production."

Reporting committee: Social, Health and Family Affairs Committee (Doc. 7680).

Committee for opinion: Committee on Science and Technology.

Reference to committee: Doc. 7344 and Reference No. 2018 of 25 September 1995.

Opinion approved by the committee on 30 January 1997.

Secretaries to the Committee: Mr Perin and Mr Torcătoriu.

1 ¹by the Committee on Science and Technology