Sep 19, 2008

Revisiting Chernobyl

Posted in Science at 1:00 pm by David Bradley -- 5 Comments; add your comment

Chernobyl. The very name strikes fear into the hearts of those who hate everything about the nuclear industry. It conjures up images of an archaic, burning industrial site spewing out lethal fumes, of farm animals dying of radiation poisoning in their thousands and contaminated meat, of ecosystems devastated, and of people with radiation sickness and for those spared the acutely fatal toxicity, the prospect of cancers to come and perhaps generations of mutations. But…

Korean researchers argue that while the 1986 accident at the Chernobyl nuclear power plant, Ukraine, was the worst catastrophe involving radiation to humans, but has led to an unfortunate and unwarranted degree of radio-anxiety. It is not radiation that is the health issue, but this anxiety.

Chong-Soon Kim of the Korea Institute of Radiological and Medical Sciences and colleagues say that despite warnings of pent up health problems from Greenpeace and the World Health Organisation (WHO), “there is no convincing evidence that the incidence of leukaemia or solid cancers have increased in the exposed populations.” They add that the apparent evidence of decreased fertility and increased hereditary effects has not been observed in the general population despite claims to the contrary.

According to the WHO, some 4000 people – emergency workers and residents – died or could die in the future because of Chernobyl. Greenpeace insists that this figure is almost 100,000 across the globe. Kim and colleagues point out first that although the incidence of thyroid cancer has increased in the Chernobyl area, it is actually regions less contaminated by radiation where the greatest incidence has been reported.

“In this case we have to be cautious on the point that the results came from extrapolation using insufficient individual doses, and so far
deaths
from cancer
have not been
reported as predictedso far deaths from cancer have not been reported as predicted,” say Kim and colleagues.

The radiation exposure level is the most important factor to estimate the cancer risk due to the Chernobyl accident. There are three types of exposed people. First, the exposure of recovery operation workers ranged up to about 500 millisieverts for a short period after the accident, with an average of about 100 mSv. In the case of evacuees, the average dose estimate of Ukrainian evacuees is 17 mSv (range 0.1-380 mSv), and the estimate for the Belarusian evacuees is 31 mSv, with a maximum of about 300 mSv. The average effective dose estimate of the general population in contaminated areas from 1986 to 2005 (some 5 million people) is 10-20 mSv.

The impact of Chernobyl on mental health and the future of nuclear as a viable renewable energy industry with public support, is perhaps the most serious problem. Among residents of the region and the emergency workers major psychological problems, such as depression, anxiety, and post-traumatic stress disorder are common. Anxiety levels are reported to be twice as high as in controls, the researchers say.

“Health effects, including cancer deaths, due to the Chernobyl accident have not reached the serious situation that was predicted,” the researchers say. There is, of course, some uncertainty in these figures although solid cancers usually form over a fifteen year period, rather than twenty years.

Young Woo Jin, Meeseon Jeong, Kieun Moon, Kwang Hee Yang, Byung Il Lee, Hun Baek, Sang Gu Lee, Chong Soon Kim (2008). Health effects 20 years after the Chernobyl accident International Journal of Low Radiation, 5 (3) DOI: 10.1504/IJLR.2008.020255