John Vidal questions whether official estimates of the risk of radiation exposure are accurate, and points to health effects around Chernobyl as a clear indication that they are not (Nuclear's green cheerleaders forget Chernobyl at our peril, 2 April). There is no doubt that the high level of exposure of infants to radioactive iodine in heavily contaminated areas of the former USSR has led to more than 6,000 cases of thyroid cancer; but the evidence for health effects attributable to Chernobyl exposure beyond these thyroid cancers is much less clear. This is largely because the radiation doses received by other tissues (and by thyroid glands outside these areas) were so much lower. The United Nations Scientific Committee on the Effects of Atomic Radiation has recently reviewed the available data and reiterated this conclusion. It needs to be recognised that socioeconomic conditions in the countries of the former USSR during the 90s led to widespread health effects, which can be seen in, for example, the far east of Russia that was hardly affected by Chernobyl contamination.
Radiological protection professionals come under pressure not only from that wing of opinion suggesting that radiation risks have been greatly underestimated, but also from those on the opposite wing who suggest that there is no risk from low doses of radiation, or even that such doses are beneficial – an example of these views can be found in an article by Wade Allison on the BBC News website (http://bbc.in/eJCMF7). Those responsible for radiological protection have to walk a difficult fine line between these frequently vociferous camps.
Professor Richard Wakeford
Visiting professor, Dalton Nuclear Institute, University of Manchester
• I helped bring the increase in thyroid cancer to the attention of the west when we published the result of our studies in Belarus in the journal Nature in 1992. I have continued to work on the radiation-induced thyroid cancers that are still occurring. Tragically, deformed babies occur in every society and being shown a ward full of such children and being told they are the result of Chernobyl does not constitute proof that they are due to radiation exposure. What it does constitute is evidence that further studies, including dose assessment, accurate classification and epidemiology, are needed. The figures quoted by Yablokov and Nesterenko, and referred to by Vidal, are at the high end of most estimates; other figures are very much lower.
What is disgraceful is that there has been no international comprehensive scientific study of the health effects of exposure to the Chernobyl accident comparable to that set up after the atomic bombs in Japan. The health effects for those exposed to the atomic bombs are still occurring over 60 years later. The long-term effects of Chernobyl, with a very different type of exposure, will differ, and will hopefully be much less than those of the atomic bombs. Unless comprehensive studies are set up to review past evidence and carry out lifespan studies of those exposed, speculation will flourish. This was a European accident that led to fallout across the whole of Europe, and the European community should take the lead.
Professor Dillwyn Williams
Cambridge
• The government's proposals for a green investment bank, announced in the budget (Report, 24 March), are underwritten by the sale of Britain's share in Urenco. This uranium enrichment company is owned by Britain, Germany and the Netherlands. Ministers aim to raise up to £1bn from the sell-off. When the last Labour government investigated selling Britain's share in this firm, in 2008, it was reported to be valued at £3-4bn. When mooted again for sell-off in 2009, Vince Cable dismissed the idea as a "car boot sale" and "not the most prudent way to go". Yet the coalition is planning to sell Urenco with little regard for market conditions following the disaster in Japan and the events in the Middle East. I am pressing ministers for answers to the following questions about the privatisation of Urenco: first, does it represent value for money in the current market? Second, what guarantees can we be given that it does not threaten Britain's national security interests?
Luciana Berger MP
Shadow minister for energy and climate change