Geographical distribution of preconceptional radiation doses to fathers employed at the Sellafield nuclear installation, West Cumbria.

To examine whether the geographical distribution of births associated with preconceptional exposure of fathers to radiation at the Sellafield nuclear installation is consistent with the suggestion that this exposure explains the excess of childhood lymphoid malignancy in the adjacent village of Seascale. Retrospective birth cohort study. Cumbria, West Cumbria health district, and Seascale civil parish. The 10,363 children born in Cumbria during 1950-89 to fathers employed at Sellafield. The doses of external whole body ionising radiation received by fathers at Sellafield in the total time and in the six months before conception of their children; the proportions of the collective doses associated with Seascale and the rest of West Cumbria. 9256 children were born to fathers who had been exposed to radiation before the child's conception. Of these, 7318 had fathers who were exposed in the six months before conception. Overall 7% (38 person-Sv) of the collective total preconceptional dose and 7% (3 person-Sv) of the collective dose for the six months before conception were associated with children born in Seascale. Of all the children whose fathers worked at Sellafield, 842 (8%) were born in Seascale. The mean individual doses before conception were consistently lower in Seascale than in the rest of West Cumbria. The distribution of the paternal preconceptional radiation dose is statistically incompatible with this exposure providing a causal explanation for the cluster of childhood leukaemias in Seascale.