Distribution of acute leukaemia in time and space. Studies in New Zealand.

The distribution of leukaemia in time and space was examined by tracing the date of onset and the place of residence in all cases of childhood leukaemia and of acute leukaemia in adults, totalling 1,003 cases, which occurred in New Zealand during the 12 years from 1953 to 1964.Significant seasonal variations in the onset were found in adults but not in children. Time-space clustering did not occur in adults, but a significant tendency towards it was found in children aged less than 6 years. Since a similar tendency has previously been found by two other groups of investigators it is suggested that leukaemia in young children may have a different aetiology from that occurring at other ages.