Contact with hospital, drugs, and chemicals as aetiological factors in leukaemia.

45 adults with acute leukaemia or chronic myeloid leukaemia and a control group of patients from the same hospital were asked about the people they had close social contact with before their illness, and about their use of drugs and chemicals. 18 (40%) leukaemia and 6 (13%) control patients had close social contact with hospital personnel or leukaemia patients. 8 (18%) leukaemia patients, but no control patients, had been in close contact with haemotological ward personnel. These differences were statistically significant. 9 (20%) leukaemia and 4 (9%) control patients lived in the same house as healthy persons working in a hospital. No conclusion could be drawn from differences between the two groups in their use of drugs, since the possibility that they were used to treat initial symptoms of leukaemia could not be excluded. Exposure to chemicals, including weed-killers and agricultural insecticides containing a benzene-ring known to be leukaemogenic, was about the same in the two groups.