Chris Busby and Molly Cato’s research appears to support official fears that rivers do not disperse leaked radioactive substances as well as the sea.* Comparing expected and actual death rates from leukaemia in children aged 0-14 during 1981-1995, they found overall increased risk throughout the triangular area defined by Oxford, Newbury and Reading. The highest risk (2.5 times) was in Southern Oxfordshire. The second highest risk (1.9 times) in Newbury.

The findings are hardly surprising. The Oxford-Newbury-Reading triangle in the Thames valley has had more than its share of licensed radioactive emissions. The Atomic Weapons Research Establishment at Aldermaston released liquid effluents into the Thames at Pangbourne and into the River Kennet, The Atomic Energy Research Establishment at Harwell released radioactive gases into the atmosphere and liquid effluents into the Thames at Sutton Courtenay. The Royal Ordnance Factory at Burghfield also released liquid effluent into the Kennet.

These findings, however, did challenge earlier assumptions that exposure to low levels of radiation posed no health risk. Chris and Molly have consistently argued that these assumptions are and have always been invalid because they are based on the experience of Hiroshima, where people were exposed to a short term high dose external exposure. As an example, measurements of plutonium-239 and -240 in Thames Valley soil samples found more than ten times the highest amounts which would have been predicted from nuclear weapons testing fallout. Chris and Molly call for new risk levels to be established to cater for cases of long term low level exposure.

* A 1989 report from the Committee on Medical Aspects of Radiation in the Environment suggested that this might result in the population of South Oxfordshire being the most strongly affected, followed closely by Newbury, and that both these areas would be more strongly affected than areas upwind or upriver of the nuclear sites.

Up to 20,000 gallons of water containing tritium and other radioactive substances have been pumped into the Thames, the source of drinking water for many Thames-based cities and towns, every day for the last fifty years. The Atomic Weapons Research Establishment at Aldermaston (AWRE) continues to claim that these discharges are tiny, very diluted and have “virtually no effect on the environment”.

The Campaign for Nuclear Disarmament disagrees, as did many people 50 years ago when the discharges started. Declassified papers disclosed that some scientists from the Atomic Energy Authority and many Government ministers were deeply concerned at the AWRE’s dumping applications at the time, with one Conservative minister warning that the maximum emission levels proposed would cause a "measurable genetic effect" on the population. In the end, despite fierce opposition from the Water Boards, the scientists won permission for much higher levels of tritium discharge (50 rather than the original seven curies).

At the same time as the AWRE was insisting that the discharges were safe it published an "extremely confidential memo" which was withheld from the Water Boards. This stressed that it was "vitally important" that people were dissuaded from paddling, bathing or sailing in the water between the outlet pipe and the river!