Probability stacked against radiation victims: Tom Wilkie looks at how quantum physics affects leukaemia clusters

ABOUT 160,000 people died of cancer in Britain last year, some as a result of radiation exposure. But it is impossible in principle to pick out from those 160,000 the very few whose cancers were triggered by radiation. That is one reason why the families of Sellafield cancer sufferers lost their case yesterday.

According to figures from the National Radiological Protection Board, if 100,000 people each received a radiation dose of one milliSievert, then about six of them might be expected to contract fatal cancer as a result of that radiation. But about 25,000 of the 100,000 would die of cancer anyway, from 'natural' causes, and it is impossible to distinguish the radiation-induced cancers from the others. Yet to pursue a case successfully in the courts, an individual has to prove that 'on the balance of probability' his or her cancer was caused by radiation. As the above figures show, the balance of probability is always in the other direction.

Recognising these difficulties, British Nuclear Fuels, in conjunction with the UK Atomic Energy Authority, has set up a no-fault compensation scheme for its workforce.

The scheme, agreed with the unions, takes account of the probabilistic nature of radiation and spares employees the trauma of pursuing claims through the civil courts.

Whereas the courts would give an all-or-nothing settlement, under the terms of the BNFL scheme an employee can get a proportional compensation for his disease, without acceptance of legal liability by the company. Lawyers for the company and the union assess what the worker would have received had he been successful in a civil court action. The actual award is then scaled down pro rata depending on the probability that the disease is radiation-linked.

The scheme applies to employees, who were thought to be the most at risk. It was assumed that government regulations would ensure members of the public received negligibly low radiation doses, but in the early 1980s, a Yorkshire TV documentary drew attention to clusters of cases of leukaemia among children who had lived in the village of Seascale, near the Sellafield reprocessing plant.

Childhood leukaemia is a rare disease which occurs at random across the country. Because the distribution of cases is not uniform, statistical 'clusters' of the disease can appear without there being any underlying cause or common factor.

Successive investigations, by the Black Committee and the Committee on Medical Aspects of Radiation in the Environment (COMARE), have suggested that the cluster in west Cumbria is not statistical, but reflects some underlying cause. But this has not been proved beyond doubt.

Radiation results from nuclear interactions are governed by the laws of quantum mechanics. One of the least understood aspects of quantum physics is that there can be effects that do not have causes. It could be that the Sellafield cancers are an instance of this, and that yesterday's judgment demonstrated how the law of England has yet to catch up with the laws of quantum mechanics.

(Photograph omitted)