|20 May 1991 Daily Telegraph Page ( ) Edition (1178 words)
Science: Chernobyl - the final reckoning - Health Check / It has taken five years for teams of scientists worldwide to assess the effects of the world's worst nuclear accident. Science Editor Roger Highfield reports on their findings
By ROGER HIGHFIELD
THE WORLD'S worst civil nuclear accident threw out a plume of radioactivity that could be detected around the globe. Though the Chernobyl disaster took place five years ago, it is only this week that a clear picture of the effects on health will emerge in the form of a 1,500-page report.
Tomorrow, a conference at the International Atomic Energy Agency in Vienna will reveal the results of a project carried out by 200 health experts from 25 countries to assess the effect on 825,000 people in the most contaminated areas, Byelorussia, Russia and the Ukraine.
Dr Morris Rosen, assistant deputy director general of the agency, said the two-volume 10 in thick report is the most comprehensive study that has been carried out on the health effects of Chernobyl.
At the invitation of the Soviet Union, agency experts took some 2,000 measurements of gamma radiation doses, 1,000 samples of soil and grass, and samples of milk in the area beyond the 19-mile 'prohibited zone' around the stricken plant. Project teams also monitored the radiation exposure of nearly 22,000 inhabitants.
The experts, chaired by Dr Itsuzo Shigematsu, director of the Hiroshima Radiation Effects Foundation, will tackle the most controversial aspect of the accident: which of the reported health effects and deaths are due to radiation from Chernobyl, and what can be expected in the future.
While two people died immediately after the blast on April 26, 1986, at the Number 4 reactor on the Chernobyl site, and another 29 died in hospital during the next few days, the extent of longer term disease and death from radiation is harder to assess - hot spots are dotted around the country, where rainfall washed radioactivity out of the accident's plume.
Studies have been hindered by the early reluctance of the Soviet Union to release details of the calamity: a great deal of information was held back initially and it was only in 1989 that official contamination maps were released. But Dr Rosen is confident 'sufficient information was made available to conduct the study'.
Radiation poses two distinct threats: one is from huge doses that cause burns and radiation sickness. Six of the firemen who fought the blazing reactor and 23 of the reactor staff were killed this way. Another 74 have been disabled.
The second is the long-term threat of cancer that, for instance, caused 700 additional cancers over 45 years in 110,000 Japanese survivors of atomic bomb blasts (they received significantly more radiation than those around Chernobyl).
The long-term threat from Chernobyl led to the evacuation of 116,000 inhabitants within days and another 50,000 last year. Five years after the accident, there are still plans for another 200,000 to leave.
Dr John Gittus of the British Nuclear Forum, who led the UK Atomic Energy Authority team studying the consequences of Chernobyl, says that the long-term health problems caused by radiation should be impossible to detect already.
He did not expect any surprises from the agency study. However, Rosen said that 'no matter what you know in the past, there can always be surprises.
The study was aimed at clarifying the situation'.
For solid cancers, studies of the Hiroshima and Nagasaki bomb survivors show a five- to 10-year latency period before excess cases appear. Leukaemias and thyroid cancers may be expected to be occurring already, but the incidence is swamped by the 'normal' incidence. That is why the current reporting of ill-health around Chernobyl is suspect.
The UKAEA estimates that Chernobyl will eventually cause 10,000 excess cancer deaths in the Soviet Union. This represents only 0.03 per cent of the natural Soviet cancer rate, against an increasing incidence of cancer through pollution. The whole world figure is about 40,000 cases out of a total death toll of over 500 million during the same period.
One major stumbling block for the agency is that it may not be able to determine how many cancers are due to Chernobyl because of the primitive local health system, typified by the fact that one third of the hospitals in the surrounding area do not have running water. As a result, there is scant health data from before the accident to use as a baseline for the agency study. This undermines their ability to calculate the effect of radioactive iodine, which is concentrated in the thyroid gland.
There were few reliable statistics for comparison on goitre - thyroid enlargement - which is endemic in the area.
Another complication is the health effects of stress. Inspection teams from the agency have reported that the largely rural local population blamed a variety of illnesses on radiation, even when this was clearly not the cause.
'They are living in anxiety, wondering if they should be evacuated,' Rosen said. Such radiation angst was noted in the aftermath of the 1979 nuclear accident at Three Mile Island in America.
The reported doubling of the frequency of high blood pressure, diabetes, heart disease, nervous conditions and pulmonary disorders are thought to be due more to feelings of depression and helplessness than to the effects of radiation.
The secrecy of the Soviet regime undoubtedly fuelled the stress. Distrust of the government meant that anxiety-related illnesses surged after the Russians released radiation data in 1989.
But those studied by the agency in the worst affected areas are by no means the only ones affected by the accident. More research is needed to learn about two groups of particular concern - the 600,000 so-called liquidators brought in to clean up after the accident and the 'biorobots', soldiers who had to dart to the edge of the burning reactor to throw in radioactive debris.
The latter group was given one minute to clear debris in radiation that was potentially lethal after five minutes' exposure. Vladimir Chernousenko, a member of the clean-up team, claims that between 7,000 and 10,000 of the liquidators have died because of exposure to radiation.
His allegations, shown on Thames Television, have been dismissed by the Soviet Ministry for Nuclear Power and Industry, and questioned by Western experts who have studied the consequences of the Chernobyl accident.
Malcolm Grimston of the UKAEA says that the death toll given by Chernousenko is consistent with the natural mortality rate in the Soviet Union among a population of 600,000 relatively fit young people aged between 35 and 40.
'It seems disingenuous to put all deaths in the area down to Chernobyl,' he said.
Despite the general rejection of Chernousenko's claims, there is no doubt that the biorobots and even the Soviet scientists working at Chernobyl used radiation precautions which are primitive by Western standards. The toll on their health will be covered by a new study.
A year ago, the Soviet Union began to set up a register at Obninsk, 60 miles south-west of Moscow, to co-ordinate research on the liquidators and biorobots.
Until recently, the Soviet Union has been unco-operative about releasing details of the calamity, but has now decided to give substantial backing to a dollars 200 million World Health Organisation project - launched last week - to investigate effects of the disaster until 2011.
Copyright: Telegraph Group Ltd