Læknablaðið - 01.10.1968, Page 61

LÆKNABLAÐIÐ
219
DEATHS IN AMERICAN RADIOLOGISTS
<
LU
CC
UJ
Q-
— PERCENT DUE TO LEUKEMIA
—
- (MARCH)
_ (WARREN)

1 1 i i i l l i i i U.S.MALES AGE 25 *—« i l l l i l l 1 1 i
1940
1945
1950
1955
1960
Fig. 4.
Percentage of all deaths of radiologists caused by leukemia in the
period 1940—1960. The figures of March and Warren are contrasted.
Note the decrease as better precautions were taken against occupa-
tion.al radiation.
Among the heavily exposed survivors of the atomic l)lasls
at Hiroshima and Nagasaki there has heen an excess of
leukemia,14 mostlv of acute myelocytic type. Tlie j)eak incidence
occurred ahout 10 years after the bombing, and at the present
time the number of cases is only moderately in excess of that iu
the Japanese population as a whole. Tnterestingly enough,
myelocvtic leukemia is the more prevalent type in the Japanese
than in Caucasian ])opulations, \\here the lymphocytic form is
also quite common. About five per cent of the most heavily
exposed survivors have developed leukemia, whereas only a slight
excess ahove the incidence in the Japanese population as a whole
(Fig. 5) has heen found in the least exposed. Most of these
survivors had receivcd whole-hody or nearly whole-body radiation
from barely sublethal amounts, in the vicinity of 400 or more
R, ranging down to exposures hardly more than those at the
level of natural background radiation.
It is difficult to estimate the exposure received by some of
the pioneer radiologists who developed leukemia, hut from the