Evidence of space-time clustering of childhood acute lymphoblastic leukaemia in Sweden.

We have examined 645 recorded cases of childhood acute lymphatic leukaemia (ALL) in Sweden during 1973-89 to identify space-time clustering by using the close-pair method of Knox. The records included date of birth and of diagnosis as well as addresses at birth and at diagnosis. There was a significant excess of case pairs close in date of birth and place of birth in the 5- to 15-year age group.