Of the estimated 205,000 military personnel who participated in the US atmo
spheric nuclear weapons testing program from 1945 to 1962, less than 1 % ha
d ionizing radiation doses that met or exceeded the current federal occupat
ional guideline for dose of 5 rem (roentgen equivalents in humans) in a 12-
month period. The objective of this study was to determine whether veterans
who received the highest gamma radiation doses (n = 1010) have experienced
increased cancer mortality compared with a group of Navy veterans who rece
ived a minimal radiation dose as participants of HARDTACK I (n = 2870). Mor
tality from all causes of death (relative risk, 1.22; 95 % confidence inter
val, 1.04 to 1.44) and from all lymphopoietic cancers (relative risk, 3.72;
95 % confidence interval, 1.28 to 10.83) was significantly elevated among
the 5-rem cohort compared with the Navy controls. The lack of statistically
significant excesses in deaths from many of the known radiogenic cancers s
uggests that the observed excess mortality, may be the result of many facto
rs, of which radiation exposure was only one.