From James E. Cleaver, University of California, San Francisco
Wade Allison suggests we are being over-cautious in our safety limits for ionising radiation (31 July, p 24). He pursues the elusive idea that there could be a safe level of radiation for the human population. But his article conflates two different issues, one scientific and the other societal.
The best available scientific evidence, both epidemiological and laboratory research, was weighed up by the US National Academy of Sciences in a 2006 report. This determined that the dose-effect relationship is linear down to the lowest doses such that there is no safe dose of radiation, only permissible doses.
How do you decide what level of additional health risk to the population should be permissible, given the rates of cancer from other causes in the population? Would that be 1 cancer per 100 exposed individuals or 1 cancer per million? There needs to be careful attention to the costs and benefits to society before recommending any increase to our radiation exposures.
From Roy Harrison
Advertisement
The suggestion that relaxing radiation exposure limits would lead to a large reduction in the cost of nuclear power is curious. Many costs, such as having three independent emergency cooling systems, are caused by the need to avoid breach-of-containment incidents, which can lead to a large tract of land being contaminated to a level not acceptable to Wade or anyone else.
The nuclear industry makes every effort to avoid such incidents, but then pretends that they could never happen and refuses to discuss the consequences of such breaches. It is obvious that they are possible. Apart from the infinite ingenuity of human beings to find exciting new ways of screwing things up, nuclear plants are not armoured sufficiently to protect against a military attack.
So many people will oppose nuclear power plant construction, having Chernobyl in mind, when the actual consequences may turn out to be orders of magnitude less serious than this – if they could be discussed.
Romsey, Hampshire, UK
San Francisco, California, US
