Chernobyl link to rising cancer rates
Scientific evidence that fallout from Chernobyl may have raised cancer rates in western Europe has emerged for the first time.
Researchers in Sweden identified a suspicious increase in cancer incidence in parts of the country exposed to the radiation cloud from the nuclear disaster.
They said the trend, though not dramatic, was "somewhat unexpected".
It showed a statistically relevant correlation between the degree of fallout and an observed rise in the number of total cancer cases.
This was despite a relatively short exposure time and low doses of radiation. An estimated 300 extra deaths may have occurred as a result of cancers acquired between 1988 and 1996, said the scientists.
Britain's radiation watchdog, the National Radiation Protection Board (NRPB) is to study the research.
The explosion at the Chernobyl power plant in the Ukraine on April 26, 1986, was the world's worst nuclear accident. It killed 31 people and released a plume of radioactive caesium that was blown across Europe.
In the Ukraine, 3.7 million people were affected by radiation and more than 160,000 inhabitants had to be resettled.
The radiation cloud drifted for thousands of miles. Several days after the explosion a blanket of poisonous caesium fell over England, Wales and the south and west of Scotland.
Restrictions were imposed on about 10,000 sheep farms, costing the British taxpayer an estimated £13 million in compensation.
Last year sheep on almost 400 British farms were still having to be monitored with radiation detectors before being sold for human consumption.
Fish were also affected. Three years after the accident, contaminated trout, pike and perch continued to turn up in British rivers.
The impact on human health emerged from studies in Belarus, Ukraine, and western Russia which showed dramatic increases in thyroid cancer incidence in children.
But the Swedish study is the first to produce evidence of illness linked to Chernobyl outside the former Soviet Union.
Five per cent of the radioactive caesium was deposited on northern Sweden by heavy rainfall on April 28 and 29, 1986.
The fallout was unevenly distributed and involved much lower exposure than occurred in eastern Europe.
A team of scientists led by Martin Tondel, from Linkoping University, divided the parishes of seven northernmost Swedish counties into six classes based on ground coverage of the radioactive isotope, Caesium-137.
Of a total of 450 parishes, 333 were affected by the fallout. One class, comprising 117 parishes, received no fallout and the people living there were used as a baseline comparison group.
Individuals up to the age of 60 who were resident in the parishes at the time of the disaster were included in the study.
Out of a total of 1,143,182 people, 22,409 cases of cancer were registered during the years 1998 to 1996.
Analysis of the data showed that cancer rates rose alongside elevated levels of radiation exposure.
A 0.11-fold excess risk was observed for every 100 kiloBecquerels of radiation per square metre.
The scientists, who took account of confounding factors such as smoking and population density, wrote in the Journal of Epidemiology and Community Health: "Unless simply representing a chance phenomenon, the findings in our study are somewhat unexpected indicating a possible cancer effect of the Chernobyl fallout in north Sweden despite a short latency period and low degree of exposure."
The scientists said if the effect was real, it showed that the risk from low dose radiation may be greater than that predicted by international guidelines.
However they acknowledged that a "crucial question" was whether some unidentified risk factor for cancer might have swayed the results.
Another factor was that the trend only applied to total cancer rates, not the risk of individual cancers - including thyroid which is particularly sensitive to radioactive caesium.
Dr Mike Clark, scientific spokesman at the NRPB, which advises the Government on radiation issues, said: "We will look at this work carefully. They report an increase in general cancer rates in northern Sweden after Chernobyl but not in thyroid cancer.
"This is unexpected, given the definite increase in thyroid cancer observed in the former Soviet Union due to Chernobyl. The authors comment themselves on this rather odd result."
He added that there was no clear increase in leukaemia rates, which might be expected if radiation was involved.
However no obvious impact on leukaemia has yet been seen in even the most heavily polluted areas of the former Soviet Union.
The association between leukaemia and radiation is based on the effects of the atomic bombs dropped on Japan at the end of the Second World War.
It has been suggested that the leukaemia danger might be unique to the very high-dose, short-duration radiation exposures experienced after a nuclear bomb blast.
