Radiation workers in child cancer link link

A study of workers exposed to radiation shows they are more likely to have children who develop leukaemia. But their increased risk is not linked to radiation exposure. Jeremy Laurance, Health Editor, explains how the findings effectively dispel the fears of a link which surfaced 15 years ago, but leave questions about the causes of childhood leukaemia unanswered.

Workers in nuclear and other industries who are exposed to radiation have a 77 per cent higher risk of fathering a child who develops leukaemia, according to one of the largest studies yet conducted.

However, the findings by the Childhood Cancer Research Group at Oxford University, show that the risk of having a child with leukaemia was not linked with the size of the radiation dose. In fact, men with the highest risk received the lowest or zero doses. The study, published in the British Medical Journal, is the most definitive so far to counter the 15-year- old hypothesis that living near to or working in a nuclear power station increases the risk of cancer.

Alarm over a link between nuclear power and leukaemia was triggered in 1983 with the broadcast of the Yorkshire Television documentary, The Nuclear Laundry, which claimed that the high level of childhood leukaemia in the Cumbrian village of Seascale was linked with the nearby nuclear reprocessing plant at Sellafield.

The programme's claims gained scientific credibility following publication of a study, also in the BMJ, by the respected cancer epidemiologist Martin Gardner, which appeared to show that exposure of men to radiation before conception increased the risk of leukaemia in their offspring. Exposure to radiation, it was suggested, might damage the genetic material in the men's sperm.

The BMJ describes the "Gardner hypothesis" as one of the most important papers it has published in the last 15 years. However, despite the efforts of researchers in the UK and abroad, no group has ever succeeded in replicating its findings.

The new study, led by Dr Gerald Draper, director of the Childhood Cancer Research Group, "almost finishes" the Gardner hypothesis, the BMJ says. It concludes that the most likely explanation for the increased risk among radiation workers is exposure to infection resulting from mixing of the population.

This theory suggests that childhood leukaemia may be a rare reaction to infection which is more common when there is a big influx of people to an isolated rural community, as when a nuclear power station is being built.

Although the 77 per cent increase in risk for radiation-exposed workers looks high, the absolute risk is still small. There are 6.5 cases of leukaemia and the related condition non-Hodgkin's lymphoma per 10,000 children under 15, and the study authors estimate that this is raised to 11.9 per 10,000.

Dr Draper said: "The public alarm over living near a nuclear power station is overdone. The popular conception that there are lots of cancers around them is wrong."