4-31. ACUTE RADIATION SYNDROME
The acute radiation syndrome (ARS), due to whole-body x- or gamma radiation,
may reflect a variety of illnesses that are dose-dependent. Three major biological
systems emerge as the centers of concern, depending upon the amount of radiation
received at the time of exposure. They are the hematopoietic (marrow) system,
gastrointestinal (GI) system, and the central nervous (brain) system.
a. The marrow ARS is evident between doses of 100 rad and 600 rad. Extreme
depression of the blood cells results in severe anemia and overwhelming infection.
Deaths average from 20 percent at the lower end of the range to 100 percent at the
upper extreme. Medical treatment is extremely complicated and of long duration, but
b. The GI ARS is evident in dose ranges of 300 rad to 1,000 rad. The classic
picture is bloody diarrhea and dynamic ileuse, resulting in severe fluid and electrolyte
loss. Deaths are 100 percent as there is no effective medical treatment.
c. The brain ARS, following somewhat higher exposures, is also 100 percent
fatal. Incapacitation is produced in less than 10 minutes. The classical symptoms are
convulsions progressing to coma and death. Cause of death is a sudden and
overwhelming cerebral edema. Obviously, there is no effective treatment.
4-32. CHRONIC EFFECTS
It should be noted that chronic effects are not qualified by the whole or partial-
body exposure theories. Chronic effects can and do result from intermediate dose
ranges, and even from very low dose ranges if exposure is repeated often enough.
a. Radiation exposures increase the incidence of certain types of cancer in man.
While the exact mechanism of this damage is not known, repeated radiation damage
and repair seems to account for some cases; whereas in others, the occurrence of
somatic cell mutations seems an attractive hypothesis. Earliest evidence was the
occurrence of skin cancers at the site of repeated x-ray burns among the early x-ray
workers. Bone tumors were markedly increased among the radium watch dial painters.
b. Increases of leukemia incidence have been documented, particularly among
early radiologists. Since 1911, when four cases were described, the incidence of
leukemia among radiologists has increased. The rate in 1952 was some eight times
greater than among the general population. This reflects the fact that the early
radiologists were reaching the age at which the delayed effects become more obvious.
Since that time, however, the use of protective devices and procedures has caused the
incidence of leukemia among radiological workers to become more nearly comparable
to that of the general population.