The recorded incidence of leukemia and lymphomas has markedly increased during the past 30 years. During the same interval the amount of ionizing radiation in the environment has been steadily increased by man-made additions to the natural background.
The possibility that radiation may account in part for an increasing incidence of leukemia is suggested by the more frequent development of the disease in those exposed to large amounts of radiation.
Although the extent of increase in the risk of leukemia cannot be determined accurately from the recorded rates and the relation between leukemia incidence and radiation dose cannot be estimated precisely, it appears probable that radiation is only one of many environmental agents influencing the occurrence of the disease.
Other factors associated with the changing standard of living, such as the increasing use of marrow-depressing drugs and the growing contamination of the atmosphere with chemical pollutants, deserve further investigation as leukemogenic influences.