"The legacy of Chernobyl will stay with us for a long time in the shape of radiation-induced diseases and psycho-somatic disorders," said Dr Wilfried Kreisel, Executive Director in charge of Health and Environment at the World Health Organization. Speaking on the last day of the International Conference on Health Consequences of the Chernobyl and other Radiological Accidents here in Geneva, he pointed out that "the WHO would want to see the volume and quality of medical assistance and scientific research increased. We shall be doing a disservice if we shall fail to extract benefits for mankind out of this monumental human tragedy. If history is not to repeat itself we should learn very well the lessons of Chernobyl".
The largest nuclear reactor radiation accident occurred on 26 April,1986 at the Chernobyl nuclear power plant in the Ukraine. Heavy contamination was spread over vast regions of Belarus, Russia and Ukraine. The Chernobyl accident resulted in acute radiation sickness of 134 persons and the death of 30 workers at the reactor site and the exposure to ionizing radiation of some five million people living in areas affected by significant fallout of radioactive nuclides.
Nearly ten years after the Chernobyl accident, scientists attending the Conference have identified three main areas of concern: the large increase in psychological disorders, especially among accident recovery workers and people living in the highly contaminated areas; the health impact of the thyroid cancer incidence among children; and, future cancers which could occur in people, particularly leukaemia, breast cancer, bladder cancer and kidney diseases.
There is a definite increase in thyroid cancer mostly in children but also in adolescents following the Chernobyl accident with nearly 400 cases in Belarus, 220 cases in the Ukraine and 62 cases in the Russian Federation. These cancers are extremely aggressive and locally invasive. There is strong circumstantial evidence that an increase in thyroid cancer in these three countries is due to radioactive fall-out which followed the Chernobyl accident.
This is demonstrated by:
The geographical distribution of the cases which overlaps with that of the radioactive plume.
The time trends: rates of thyroid cancer in children and adolescents were low and stable until around 1990 but increased sharply since.The increase is apparent in the populations of children born before the accident. Among those conceived later the rates are similar to those observed before the accident.
The results of a case control study carried out in Belarus and presented at the Conference.
It is still not clear which are the radioactive agents responsible for the increase. A likely cause is iodine 131, but when used in medical practice this isotope has not been shown to cause thyroid cancer.
There is a need therefore to investigate the role of iodine 131, of other short-lived isotopes, and of external radiation. Could the increase have been caused by a mixture of radioisotopes? Is it possible that iodine 131 was changed itself? It is especially important to clarify the role of factors modifying the risk of radiation-induced cancer, such as genetic predisposition, iodine deficiency and prophylaxis and of other possible environmental contaminants.
Such a rapid increase in cancer incidence is probably unprecedented and provides a unique opportunity to understand what causes cancer and to identify factors which may be important for cancer prevention. This requires coordinated and well-designed studies that incorporate dosimetric, epidemiological,clinical, pathological and molecular biological methods.
Discussions of the acute effects of radiation revealed new developments in treatment of persons exposed to high doses of radiation. Acute effects include radiation sickness and localized injuries, such as burns. The usual symptoms include: vomiting, nausea, rapid weight loss and significant falls in blood count. The new technique is based on the use of specialized growth factors to stimulate the blood forming system to re-populate the cells lost due to radiation exposure.
Dr Angelina Guskova, Chief, Clinic for Acute Radiation Injuries at the Institute of Biophysics, Moscow, while sharing with her audience her experience in treating patients suffering from acute radiation effects, pointed out the following main lessons learnt from the accident: the need for the highly exposed patients to be treated in one or two specialized centres with a uniform approach to diagnosis, treatment and administration of patients. The greatest difficulties occur when total body doses exceed 8-13 Gray (Gy), when localized severe injuries occur and when radionuclides are ingested in large concentrations.
Although so far there has been no statistically measurable increase in leukaemia and other similar blood disorders, scientists are warning that the peak may occur within the next few years accompanied by greater incidence in breast cancer, cancer of the bladder and kidney diseases. Preliminary reports on the health status of accident recovery workers indicate that the increase is beginning to show. Pursuing humanitarian and public health goals, WHO is establishing a separate Chernobyl-related project, together with acollaborating centre in St Petersburg, Russia, which will address the problems of the accident recovery workers of whom there are approximately 800 000.
The participants at the Conference concluded that psycho-social effects is a priority area which should be addressed in a much more serious way both by the three affected states and the international community. Similarities in behaviour patterns on the part of the victims and unaffected populations were observed among the Japanese bomb survivors and those affected by the Chernobyl fall-out.
In Japan, bomb survivors were discriminated against by prospective employers because they may contract cancer at a later time. Similarly, people evacuted from contaminated to clean areas after the Chernobyl accident were shunned by local residents because the evacuees were provided with new houses and pensions.
Evacuation and relocation of large groups of people after the Chernobyl accident, as well as constant concern and fear of radiation exposure have resulted in a rising number of health disorders being reported to local outpatient clinics. Studies show that headaches, chest pains, intestinal disorders, sleep disturbance, loss of concentration and alcohol abuse are common. This is clearly a priority area not only for the governments and public health services of the three affected states but for the international community as a whole. Similar psycho-social impact can be observed in the wake of earthquakes, fires, floods and other natural and man-made disasters. WHO is addressing this problem through its recently created Radiation Emergency Medical Preparedness and Assistance Network (REMPAN).