D. G. BROWN 
881 
Figure 4. — A swine exposed unilaterally (left side) 
to 550 rads of bomb radiation. The animal was 4 
months old at time of irradiation. Unilateral atrophy 
of the tissues in the hip and thigh was a common 
lesion in those swine exposed to doses exceeding 250 
rads of bomb radiation. 
with the more numerous pathological changes 
often masking the primary cause (s) of death. 
The major causes of death were chronic dis- 
eases. Less than 25% of these swine died of 
acute and peracute diseases. 
The mean postirrediation survival time for 
the irradiated swine (all doses combined) was 
8.3 years for the males and 7 years for the fe- 
males; and, for the control swine, 9 years for 
the males and 7.9 years for the females. Re- 
gression of survival time on dose (Figure 8) in- 
dicated a significant life-shortening effect on 
the females (P < 0.05) ; however, the regres- 
sion coefficient for the males could not be de- 
clared different from zero. The effect on the 
females might have been related to the high in- 
cidence of genital tumors occurring earliest in 
and contributing to the deaths of the females 
in the highest dose groups. Mortality in the ir- 
radiated males v^as more erratic in relation to 
dose. The data of both sexes combined indicate 
that life shortening was approximately 3 % per 
100 rads. 
SUMMARY 
The LD 50/30 values for swine exposed to ioniz- 
ing radiation were presented. The range of 
values were discussed with emphasis on specific 
variables which influenced the dose-mortality 
response. 
Late effects of mixed gamma-neutron (bomb 
radiation) and X-irradiation were studied in 
swine throughout their life span. Neoplasms 
occurred earlier with a higher frequency in the 
irradiated swine than in the nonirradiated con- 
trols. Life shortening due to irradiation was ap- 
proximately S% per 100 rads. 
REFERENCES 
1. Rust, J. H., Trum, B. F., Wilding, J. L., Simmons, 
C. S., and Comar, C. L. Lethal dose studies with 
burros and swine exposed to whole-body cobalt-60 
irradiation. Radiology 62:569-574, 1954. 
2. Nacktwey, D. S., Ainsworth, E. J., and Leong, 
C. F. Recovery from radiation injury in swine as 
evaluated by split-dose technique. Radiat. Res. 
31:353-367, 1967. 
3. TuLLis, J. L., Chambers, F. W., Jr., Morgan, J. E., 
and Zeller, J. H. Mortality in swine and dose dis- 
tribution studies in phantoms exposed to super- 
voltage Roentgen radiation. Amer J. Roentgenol., 
Radium Ther. Nucl. Med. 67:620-627, 1952. 
4. Woodward, K. T., McDonnel, G. M., Harris, P. S., 
KiRKLAND, W. J., and Shively, J. N. The response 
of swine after exposure to the gamma-neutron 
flux of a nuclear detonation. Amer. J. Roentgenol., 
Radium Ther. Nucl. Med. 85:179-185, 1961. 
5. Chambers, F. W., Jr., Biles, C. R., Bodenlos, 
L. J., and Bowling, J. H. Mortality and clinical 
signs in swine exposed to total-body cobalt-60 
gamma irradiation. Radiat. Res. 22:316-333, 1964. 
6. Brown, D. G., Johnson, D. F., and Auxier, J. A. 
Unilateral and bilateral exposure of swine to fis- 
sion neutrons. Health Phys. 21:537-545, 1971. 
7. Brown, D. G., and Haywood, F. W. 14 MeV neu- 
tron irradiation of swine. (Unpublished data). 
8. TuLLis, J. L., Lamson, B. C, and Madden, S. C. 
Mortality in swine exposed to gamma radiation 
from an atomic bomb source. Radiology 62 : 409- 
415, 1954. 
9. Brown, D. G., Cross, F. H., and Gramly, W. A. 
Effect of ""Co gamma radiation dose rate on 30-day 
mortality in swine. Amer. J. Vet. Res. (in press). 
10. Bond, V. P., and Robinson, C. V. A mortality 
determinant in nonuniform exposures of mammal. 
Radiat. Res. (Suppl.) 7:265-275, 1967. 
11. Kallman, R. F. The effect of dose-rate on mode of 
acute radiation death of C57Bo and BALB/c mice. 
Radiat. Res. 16:796-810, 1962. 
12. LiGiE, L. C, Harris, M. D., Iatsch, R. E., and 
Van Hooser, E. N. An analysis of the LD50/30 as 
related to radiation intensity. Radiat. Res. 12:349- 
356, 1960. 
