In the early 1990s concern was raised in the United Kingdom about the effect of nuclear power plants on unborn children, when clusters of leukaemia cases were discovered nearby to some of these plants. The effect was speculative because clusters were also found where no nuclear plants were present, and not all plants had clusters around them. Detailed studies carried out by the Committee on Medical Aspects of Radiation in the Environment (COMARE) in 2003 found no evidence of raised childhood cancer around nuclear power plants, but did find an excess of leukaemia and non-Hodgkin's lymphoma (NHL) near other nuclear installations including Sellafield, AWE Burghfield and UKAEA Dounreay. COMARE's opinion is that "the excesses around Sellafield and Dounreay are unlikely to be due to chance, although there is not at present a convincing explanation for them".