- Email: [email protected]
Lactation and Radionuclide Metabolism Responses of Dairy Cattle to Lethal Doses of Gamma and Neutron Radiation1
LACTATION AND RADIONUCLIDE
METABOLISM
D A I R Y C A T T L E TO L E T H A L
RESPONSES
OF
DOSES OF GAMMA AND
NEUTRON RADIATION 1 R. G. CRAGLE, J. K. MILLER, E. W. SWANSON, AND D. G. BROWN Agricultural Research Laboratory of The University of Tennessee, Oak Ridge ~ AND
Dairy Department, University of Tennessee, Knoxville ABSTRACT
Seven lactating dairy cows were irradiated, to study the effects of lethal doses of gamma and neutron radiation on subsequent lactation. Irradiation effects on radioiodine and radiostrontium metabolism also were studied. Gammairradiated cows continued to eat and to produce milk of normal composition at moderately reduced rates for 12-14 days post-irradiation, at which time a general systemic infection occurred, miik secretion and feed intake ceased, and the animals died in three or four days. Radioiodine and radiostrontium concentrations were less in the milk from irradiated animals than from nonirradiated control cows. Immediately after irradiation the neutron-treated cows exhibited a drastically reduced feed intake and milk production dropped sharply. Two of these animals died 20 and 40 days post-irradiation, respectively. Similar rad doses for gamma and neutron treatments were given in 21.8 and 0.43 hr, respectively.
Lethal irradiation effects on lactating dairy cows assume importance if nuclear release conditions should prevail. First, if dairy animals can be used to convert livestock feeds into milk for a period of time after lethal irradiations, this knowledge would be important in survival planning. Secondly, the manner in which irradiated cows metabolize fission products becomes important in making prediction for human ingestion under these circumstances. The effects of lethal doses of gamma irradiation on beef cattle have been described by Brown et al. (3). I n the present study, the effects of lethal doses of gamma or neutron irradiations on lactation were investigated. The effects of lethal irradiations on radioiodine and radiostrontium metabolism also were studied. EXPERI~CIESITAL PROCEDURE
Seven lactating dairy cows were irradiated, of which four were exposed to Co~ gamma rays and three to neutrons. The gamma facility has Received for publication March 3, 1965. This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, I~noxville. ~Operated by the Tennessee Agricultural Experiment Station for the U. S. Atomic Energy Commission under Contract No. AT-40-1-GEN-242.
previously been described (6). The neutron facility was the Health Physics Research Reactor of the Oak Ridge National Laboratory (2, 4). This reactor has a fission spectrum of fast neutrons. The gamma exposures were made at the rate of 29.8 rads per hour (roentgens × .93 = rads) on a multiple source field for a total of 650 rads surface air dose. The neutron exposures were made unilaterally, with the animals being restrained in aluminum crates for the exposure time of 26 min. The neutron doses for the three animals were 649, 671, and 446 rads at mid-line (dose in air), respectively. The neutron/gamma ratio was eight for these irradiations, i.e., for each 100 rads of neutron radiation received, 12.5 rads of gamma radiation were received simultaneously. The total rads of neutron plus gamma radiation were, therefore, 730, 755, and 502, respectively (Table 1). All animals were subjected to the same postirradiation regime. They were placed in the normal stall area. A urinal was placed on each animal, so that separate urine and fecal samples could be collected. Each of the animals was given oral doses (200-300 t~c, depending on the degree of physical decay) of 1Ial and Sr ~ twice daily, beginning with the morning feeding on the second day after initiation of irradiation. This treatment continued until death or until 20 days had elapsed following the irradia-
942
RADIONUCLIDE
METABOLIS]Y[ IN
CATTLE
943
TABLE 1 Responses of lethally irradiated dairy cows Animals
Gamma 1
2
3
Neutrons 4
Dose (fads) 650 650 650 650 Dose time (hr) 21.8 21.8 21.8 21.8 Days until temperature elevation (rectal) 12 13 12 12 Highest temperature (C) 41.1 4].5 41.5 41.9 Death (days post-irradiation) 16 15 15 19 Feed intake (% of pre-irradiation level) Grain ¢ 100 100 100 100 Hay ~ 54 64 63 70 a Survivor. b 11.1% gamma radiation. Calculated on a 12-day post-gamma irradiation average, a 20-day average, and a 5-day pre-average. tion. The same radionuclide solution was used throughout a given cow's post-irradiation observation period. Feed intake was measured for five days before and throughout the 20 days or less after irradiation. Levels of 11~ and Sr ~ activity in feces and urine were measured on a 24-hr schedule, and milk was sampled on a twice-a-day schedule. I n feed intake and milk production, comparisons were made with the pre-irradiation data for the same animal. Radioisotope metabolism patterns were compared with data from three control animals. RESULTS
Syndrome. Cows 1-4, exposed to 650 rads of gamma irradiation, followed very closely the radiation syndrome described by Brown et al. (3) for nonlactating beef cows. These animals ate grain at a normal rate and hay at a reduced rate for 12-14 days post-irradiation. At this time a general systemic infection began, intestinal hemorrhage took place, rectal temperature rose to 41.0-41.6 C, milk production stopped, the animals ceased to eat, and death occurred in three to five days after the beginning of elevated temperatures, or 15 to 19 days post-irradiation (Table 1). Cows 5 and 6, given lethal neutron radiation doses, immediately exhibited a drastically reduced feed intake, and milk production decreased sharply. Cow 7, which received the 502-rad dose, did not die and continued to milk. Cow 5 died 20 days post-irradiation at a time of low leucocyte and platelet counts. She exhibited sporadic low-level eating throughout the post-irradiation period. Cow 6 was in the recovery phase of leucocyte and platelet numbers; however, this animal died of severe ulceration and blockage of the large intestine 40 days after irradiation. She ate sporadically at a very low level throughout the post-irradiation
5
6
7"
730 ~ 755 b 502 b 0.43 0.43 0.43 14 40.5 20
]2 39.6 40
.... .... ....
25 19
5 5
63 32
post-neutron irradiation
period. I n general, rectal temperatures were not as high for the two neutron lethally irradiated cows as for the gamma-treated animals (Table 1). The gamma-treated animals appeared normal for the first 12 days post-irradiation, except for a small degree of excitability exhibited during the immediate post-irradiation period. The neutron-irradiated animals acquired an emaciated appearance beginning one or two days post-irradiation. For either gamma- or neutron-irradiated antreals, the total white blood cell counts dropped from an average of 6,777/mm8 by approximately 70% during the first three days postirradiation. The lowest values were recorded nearest the time of death for gamma-irradiated cows and between Days 12 and 18 post-irradiation for neutron-irradiated cows. The platele£ counts began to decrease near the seventh day post-irradiation from a pre-irradiation average of 509 X 10~ per mm~ and continued to decline until death in the gamma-treated cows~ or until 16-21 days post-irradiation for the neutron: treated animals. Temperature elevation took place during a single 24-hr period and remained high until death in gamma-irradiated cows. Rectal temperatures were lower and fluctuated more in the neutron-treated cows. Feed intake. During the first 12 days postgamma-irradiation, Cows 1-4 consumed 100% of the grain mixture and an average of 65% of the hay, when compared to the pre-irradiation levels. Feed consumption was nearly constant during this period. Cows 1 and 2 stopped eating completely on Day 14, Cow 3 on Day 15, and Cow 4 on Day 17 (Table 1). Cow 5 ate at less than 25% of her preneutron-irradiation level and Cow 6 ate at a rate of 5% through the first 20 days postirradiation. Cow 7 was a milking survivor at
944
R.G. CRAGLE ET AL
100 days after exposure. During the first 20 days after irradiation she ate grain at 63% and hay at 32% of her pre-irradiation level (Table 1). Although her feed intake was not completely up to the pre-irradiation level at 100 days, it was improved over the immediate post-irradiation period. Milk production and composition. During the first 12 days post-gamma-irradiation, Cows 1-4 milked at an average rate of 82% of the pre-irradiation period. Milk production declined rapidly thereafter (Figure 1 and Table 2). During the entire post-irradiation period, these four animals produced an average total of 11.4 times the pre-irradiation average one-day production. Milk for the 12-day period was normal both in fat and solids-not-fat content, with averages ranging from 8.38 to 8.59% for solids-not-fat and from 4.4 to 5.8% for fat (Table 2). Abnormal milk high in fat content and limited in quantity was produced during the period of high body temperatures. During the entire post-neutron-irradiation period, Cows 5 and 6 produced only an average total of two times the pre-irradiation average one-day production (Figure 1). The nfilk was abno~'ma!, with solids-not-fat varying from 8.84 to 10.55% and fat from 5.8 to 12.0%. Cow 7 produced milk with abnormally low solids-notfa t (average 6.37%) from Days 3 through 8 post-irradiation, but thereafter produced milk of normal composition. Radioiodine and radiostrontium. The passage of I T M and Sr ~ into milk is given only for the gamma-irradiated animals (Figures 2 and 3), because of low milk production and sporadic eating for neutron-treated animals. (The ratio of isotope to feed intake varied considerably.) Significantly less of the I T M (P < 0.05) and Sr ~ (P < 0.01) per cent of dose per milliliter
LITERS PER DAY rl o DAY PRE-IRRADIATION "7 [-,u""l AVERAGES ~4~1~ GAMMA TREATED COWS
3 i ..
.
.
.
.
.
.
\
c,o w s ( a )
; I :3 5 7 9 II 13 15 17 DAYS POST-IRRADIATION FIG. 1. Comparative milk yields of gamma and neutron lethally irradiated dairy cows. was found in milk from irradiated cows than in milk from nonirradiated control animals. The reasons for these phenomena are not readily apparent, although the irradiated animals were in late stages of lactation and the control cows at mid-lactation. It was also noted that with the beginning of high body temperatures the concentrations of both I T M and Sr ~ in urine decreased, despite constant intake of these isotopes. This was apparently due to kidney failure. Induced radioactivity. Induced radioactivity resulting from neutron irradiation was measured. The first samples of blood were taken approximately 2 hr after termination of the neutron irradiation period. Mcasurement of the rate of physical decay revealed that the aetivity was the result of Na :', with no appreeiable contribution from other radioisotopes.
TABLE 2 Milk production, composition and persistency of lactation in lettmlly irradiated cows Animals
Gamma 1
Days lactation post-irradiation 14 Pre-irradiation daily production (a~:erage of t0 days in liters) 4.4 Persistency of lactation for 12 days post-irradiation ((/( of preirradiation arerage) 86 Total milk produced in the post47.5 irradiation period (liters) 8.41 Average per cent SNF (12-day period) 5.0 Average per cent fat (12-day period) " Survivor. b Six-day average. " Calculated for 20 days post-irradiation.
Neutrons
2
3
4
5
14
14
18
13
7.5 71
8.9 73
69.0 86.3 8.42 b 8.38 4.8 b 5.8
5.1 102 82.1 8.59 4.4
6.4
6
7"
9 6.7
........ 17.3 . .
100+ 8.6 60 c
.
8.7 .
....
RADIONUCLIDE
I~ETABOLISM IN
% DOSE x(IO-5/ML.)
% DOSE
x(tO'S/ME.) 120 I I0 tO0
NON-IRRADIATED
II
J COWS(5)
0~ ~J°'~'--°'~
dh~
cows (3) \
GAMMA LETHALLY
9
•
| / 51- ~
I
I
I
I
I
I
I
4 6 8 IO DAYS POST-IRRADIATION
I
•
_ I \ / I V ~" 6( o
IRRADIATEDCOWS(4)
70 I
;,
tl)
///./I, N
NON-IRRADIATED
Io
.
~ o " " " /o--o / / ~ o~,
/
80 j / ~
%
945
CATTLE
I
12
FIG. 2. Comparative secretion of orally administered I TM into the milk of nonirradiated and gamma lethally irradiated dairy cows. The estimated total-body activity for Na ~ at the time the neutron treatment was terminated was estimated to be between 1 and 2 me. Since the first measurement for Na ~ in plasma was made several hours after the animals were removed from the reactor, induced radioactive elements of very short half-life would not have been detected. DISCUSSION
The gamma and neutron irradiations received by the animals in this study were not necessarily representative of the broad range of total dosage, dose rate, and combined gamma-neutron doses to which accidentally exposed animals may be subjected. An attempt was made to control the total dose at 650-675 fads of either gamma or neutrons plus gamma irradiation; however, Cows 5 and 6 received more and Cow 7 less than this amount. In addition to total dose, rate at which the dose is delivered is recognized as a factor in response of animals to gamma irradiation (2). A t ]east one report indicates that the lethal dose level for neutron irradiation is independent of dose rate under some conditions (5). A paucity of information exists concerning the effects of combined gamma-neutron doses. One difficulty in interpretation of the gamma versus neutron irradiation data reported here lies in the fact that similar tad doses were given in 21.8 and 0.43 hr, respectively (Table 1). The differences may be due to the effects of gamma versus neutron irradiation or may be due to the dose rate discrepancy (or both). In the event of a nuclear release, it seems probable that the area contaminated with highlevel gamma radiation will far exceed the area covered by neutron radiation. In addition, the
:Y,
o......o
/
~/~
\./ o~° --'°,. ~0
"/X
\o.....o~O---o
GAMMALETHALLY IRRADIATEDCOWS(4)
' ;'
;
DAYS POST-IRRADIATION FIG. 3. Comparative secretion of orally administered Sr s9 into the milk of nonirradiated and gamma lethally irradiated dairy cows. neutron radiation will be of short duration and will coincide to a large extent with the blast and thermal area in nuclear explosives. It appears that gamma radiation represents the condition under which the greatest number of animals will be exposed. The salvage of animal and animal product for human food should, therefore, be greatest in the gamma exposure area. I t is apparent that the carcasses of either neutron or gamma lethally irradiated animals can be salvaged for food if slaughtered shortly after exposure. Many of these animals in the exposure range studied in this investigation will be satisfactoi T for slaughter for a period of at least 12 days before bacterial infections begin and elevated temperatures are evident. Those animals receiving predominantly neutron irradiations would not maintain a constant weight during this tinle, due to a lack of appetite, and would produce only a small amount of milk. Those animals exposed to lethal levels of gamma irradiation could be used for milk production for a period of up to 12 days and still have a usable carcass. There is no indication that either strontium or iodine is passed more readily into milk as the result o£ lethal doses of gamma irradiation. On the contrary, in these investigations significantly less of these two fission products was passed into the milk of the gamma-treated cows versus the nonirradiated control animals. Since lethal irradiation did not result in an increased seeretion rate of iodine and strontium into milk, it would be expected that sublethally irradiated animals would respond in a sbnilar manner.
946
R. G. CRAGLE ET AL
REFEREI~CES (1) AUXlER, J. A. 1965. The Health Physics Research Reactor. Health Physics, 11: 89. (2) BATEMAN, J. L., BOND, V. P., A N D ROBERTsoN, J. S. 1962. Dose-Rate Dependence of Early Radiation Effects in Small Mammals. Radiology, 79: 1008. (3) BRowN, D. G., THOMAS, R. E., JONES, L. P., CROSS, F. H., AND SAS•ORE, D. P. 1961. Lethal Dose Studies with Cattle Exposed to Whole-Body Co~ Gamma Radiation. Radiation Research, 15:675. (4) LUNDIN, M. I. 1962. Health Physics Research
Reactor Hazards Summary, Oak Ridge National Laboratory Report 3248. August 24. (5) SPAULDING, J. F., AND SAYEG, J-. A. 1963. Dose Rate Effects on Lethality of Mice Exposed to Fission Neutrons (Abstract). I A E A Sympos. Biological Effects of Neutron Irradiation, Brookhaven National Laboratory. October 7-11. (6) WILDIIqG, J. L., RUST, J. H., AND SIMOI~S, C. S. 1952. A Multi-curie Irradiation Site for Exposure of Large Animals to WholeBody Gamma Irradiation. Nucleonics, 10: 36.
METABOLISM
D A I R Y C A T T L E TO L E T H A L
RESPONSES
OF
DOSES OF GAMMA AND
NEUTRON RADIATION 1 R. G. CRAGLE, J. K. MILLER, E. W. SWANSON, AND D. G. BROWN Agricultural Research Laboratory of The University of Tennessee, Oak Ridge ~ AND
Dairy Department, University of Tennessee, Knoxville ABSTRACT
Seven lactating dairy cows were irradiated, to study the effects of lethal doses of gamma and neutron radiation on subsequent lactation. Irradiation effects on radioiodine and radiostrontium metabolism also were studied. Gammairradiated cows continued to eat and to produce milk of normal composition at moderately reduced rates for 12-14 days post-irradiation, at which time a general systemic infection occurred, miik secretion and feed intake ceased, and the animals died in three or four days. Radioiodine and radiostrontium concentrations were less in the milk from irradiated animals than from nonirradiated control cows. Immediately after irradiation the neutron-treated cows exhibited a drastically reduced feed intake and milk production dropped sharply. Two of these animals died 20 and 40 days post-irradiation, respectively. Similar rad doses for gamma and neutron treatments were given in 21.8 and 0.43 hr, respectively.
Lethal irradiation effects on lactating dairy cows assume importance if nuclear release conditions should prevail. First, if dairy animals can be used to convert livestock feeds into milk for a period of time after lethal irradiations, this knowledge would be important in survival planning. Secondly, the manner in which irradiated cows metabolize fission products becomes important in making prediction for human ingestion under these circumstances. The effects of lethal doses of gamma irradiation on beef cattle have been described by Brown et al. (3). I n the present study, the effects of lethal doses of gamma or neutron irradiations on lactation were investigated. The effects of lethal irradiations on radioiodine and radiostrontium metabolism also were studied. EXPERI~CIESITAL PROCEDURE
Seven lactating dairy cows were irradiated, of which four were exposed to Co~ gamma rays and three to neutrons. The gamma facility has Received for publication March 3, 1965. This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, I~noxville. ~Operated by the Tennessee Agricultural Experiment Station for the U. S. Atomic Energy Commission under Contract No. AT-40-1-GEN-242.
previously been described (6). The neutron facility was the Health Physics Research Reactor of the Oak Ridge National Laboratory (2, 4). This reactor has a fission spectrum of fast neutrons. The gamma exposures were made at the rate of 29.8 rads per hour (roentgens × .93 = rads) on a multiple source field for a total of 650 rads surface air dose. The neutron exposures were made unilaterally, with the animals being restrained in aluminum crates for the exposure time of 26 min. The neutron doses for the three animals were 649, 671, and 446 rads at mid-line (dose in air), respectively. The neutron/gamma ratio was eight for these irradiations, i.e., for each 100 rads of neutron radiation received, 12.5 rads of gamma radiation were received simultaneously. The total rads of neutron plus gamma radiation were, therefore, 730, 755, and 502, respectively (Table 1). All animals were subjected to the same postirradiation regime. They were placed in the normal stall area. A urinal was placed on each animal, so that separate urine and fecal samples could be collected. Each of the animals was given oral doses (200-300 t~c, depending on the degree of physical decay) of 1Ial and Sr ~ twice daily, beginning with the morning feeding on the second day after initiation of irradiation. This treatment continued until death or until 20 days had elapsed following the irradia-
942
RADIONUCLIDE
METABOLIS]Y[ IN
CATTLE
943
TABLE 1 Responses of lethally irradiated dairy cows Animals
Gamma 1
2
3
Neutrons 4
Dose (fads) 650 650 650 650 Dose time (hr) 21.8 21.8 21.8 21.8 Days until temperature elevation (rectal) 12 13 12 12 Highest temperature (C) 41.1 4].5 41.5 41.9 Death (days post-irradiation) 16 15 15 19 Feed intake (% of pre-irradiation level) Grain ¢ 100 100 100 100 Hay ~ 54 64 63 70 a Survivor. b 11.1% gamma radiation. Calculated on a 12-day post-gamma irradiation average, a 20-day average, and a 5-day pre-average. tion. The same radionuclide solution was used throughout a given cow's post-irradiation observation period. Feed intake was measured for five days before and throughout the 20 days or less after irradiation. Levels of 11~ and Sr ~ activity in feces and urine were measured on a 24-hr schedule, and milk was sampled on a twice-a-day schedule. I n feed intake and milk production, comparisons were made with the pre-irradiation data for the same animal. Radioisotope metabolism patterns were compared with data from three control animals. RESULTS
Syndrome. Cows 1-4, exposed to 650 rads of gamma irradiation, followed very closely the radiation syndrome described by Brown et al. (3) for nonlactating beef cows. These animals ate grain at a normal rate and hay at a reduced rate for 12-14 days post-irradiation. At this time a general systemic infection began, intestinal hemorrhage took place, rectal temperature rose to 41.0-41.6 C, milk production stopped, the animals ceased to eat, and death occurred in three to five days after the beginning of elevated temperatures, or 15 to 19 days post-irradiation (Table 1). Cows 5 and 6, given lethal neutron radiation doses, immediately exhibited a drastically reduced feed intake, and milk production decreased sharply. Cow 7, which received the 502-rad dose, did not die and continued to milk. Cow 5 died 20 days post-irradiation at a time of low leucocyte and platelet counts. She exhibited sporadic low-level eating throughout the post-irradiation period. Cow 6 was in the recovery phase of leucocyte and platelet numbers; however, this animal died of severe ulceration and blockage of the large intestine 40 days after irradiation. She ate sporadically at a very low level throughout the post-irradiation
5
6
7"
730 ~ 755 b 502 b 0.43 0.43 0.43 14 40.5 20
]2 39.6 40
.... .... ....
25 19
5 5
63 32
post-neutron irradiation
period. I n general, rectal temperatures were not as high for the two neutron lethally irradiated cows as for the gamma-treated animals (Table 1). The gamma-treated animals appeared normal for the first 12 days post-irradiation, except for a small degree of excitability exhibited during the immediate post-irradiation period. The neutron-irradiated animals acquired an emaciated appearance beginning one or two days post-irradiation. For either gamma- or neutron-irradiated antreals, the total white blood cell counts dropped from an average of 6,777/mm8 by approximately 70% during the first three days postirradiation. The lowest values were recorded nearest the time of death for gamma-irradiated cows and between Days 12 and 18 post-irradiation for neutron-irradiated cows. The platele£ counts began to decrease near the seventh day post-irradiation from a pre-irradiation average of 509 X 10~ per mm~ and continued to decline until death in the gamma-treated cows~ or until 16-21 days post-irradiation for the neutron: treated animals. Temperature elevation took place during a single 24-hr period and remained high until death in gamma-irradiated cows. Rectal temperatures were lower and fluctuated more in the neutron-treated cows. Feed intake. During the first 12 days postgamma-irradiation, Cows 1-4 consumed 100% of the grain mixture and an average of 65% of the hay, when compared to the pre-irradiation levels. Feed consumption was nearly constant during this period. Cows 1 and 2 stopped eating completely on Day 14, Cow 3 on Day 15, and Cow 4 on Day 17 (Table 1). Cow 5 ate at less than 25% of her preneutron-irradiation level and Cow 6 ate at a rate of 5% through the first 20 days postirradiation. Cow 7 was a milking survivor at
944
R.G. CRAGLE ET AL
100 days after exposure. During the first 20 days after irradiation she ate grain at 63% and hay at 32% of her pre-irradiation level (Table 1). Although her feed intake was not completely up to the pre-irradiation level at 100 days, it was improved over the immediate post-irradiation period. Milk production and composition. During the first 12 days post-gamma-irradiation, Cows 1-4 milked at an average rate of 82% of the pre-irradiation period. Milk production declined rapidly thereafter (Figure 1 and Table 2). During the entire post-irradiation period, these four animals produced an average total of 11.4 times the pre-irradiation average one-day production. Milk for the 12-day period was normal both in fat and solids-not-fat content, with averages ranging from 8.38 to 8.59% for solids-not-fat and from 4.4 to 5.8% for fat (Table 2). Abnormal milk high in fat content and limited in quantity was produced during the period of high body temperatures. During the entire post-neutron-irradiation period, Cows 5 and 6 produced only an average total of two times the pre-irradiation average one-day production (Figure 1). The nfilk was abno~'ma!, with solids-not-fat varying from 8.84 to 10.55% and fat from 5.8 to 12.0%. Cow 7 produced milk with abnormally low solids-notfa t (average 6.37%) from Days 3 through 8 post-irradiation, but thereafter produced milk of normal composition. Radioiodine and radiostrontium. The passage of I T M and Sr ~ into milk is given only for the gamma-irradiated animals (Figures 2 and 3), because of low milk production and sporadic eating for neutron-treated animals. (The ratio of isotope to feed intake varied considerably.) Significantly less of the I T M (P < 0.05) and Sr ~ (P < 0.01) per cent of dose per milliliter
LITERS PER DAY rl o DAY PRE-IRRADIATION "7 [-,u""l AVERAGES ~4~1~ GAMMA TREATED COWS
3 i ..
.
.
.
.
.
.
\
c,o w s ( a )
; I :3 5 7 9 II 13 15 17 DAYS POST-IRRADIATION FIG. 1. Comparative milk yields of gamma and neutron lethally irradiated dairy cows. was found in milk from irradiated cows than in milk from nonirradiated control animals. The reasons for these phenomena are not readily apparent, although the irradiated animals were in late stages of lactation and the control cows at mid-lactation. It was also noted that with the beginning of high body temperatures the concentrations of both I T M and Sr ~ in urine decreased, despite constant intake of these isotopes. This was apparently due to kidney failure. Induced radioactivity. Induced radioactivity resulting from neutron irradiation was measured. The first samples of blood were taken approximately 2 hr after termination of the neutron irradiation period. Mcasurement of the rate of physical decay revealed that the aetivity was the result of Na :', with no appreeiable contribution from other radioisotopes.
TABLE 2 Milk production, composition and persistency of lactation in lettmlly irradiated cows Animals
Gamma 1
Days lactation post-irradiation 14 Pre-irradiation daily production (a~:erage of t0 days in liters) 4.4 Persistency of lactation for 12 days post-irradiation ((/( of preirradiation arerage) 86 Total milk produced in the post47.5 irradiation period (liters) 8.41 Average per cent SNF (12-day period) 5.0 Average per cent fat (12-day period) " Survivor. b Six-day average. " Calculated for 20 days post-irradiation.
Neutrons
2
3
4
5
14
14
18
13
7.5 71
8.9 73
69.0 86.3 8.42 b 8.38 4.8 b 5.8
5.1 102 82.1 8.59 4.4
6.4
6
7"
9 6.7
........ 17.3 . .
100+ 8.6 60 c
.
8.7 .
....
RADIONUCLIDE
I~ETABOLISM IN
% DOSE x(IO-5/ML.)
% DOSE
x(tO'S/ME.) 120 I I0 tO0
NON-IRRADIATED
II
J COWS(5)
0~ ~J°'~'--°'~
dh~
cows (3) \
GAMMA LETHALLY
9
•
| / 51- ~
I
I
I
I
I
I
I
4 6 8 IO DAYS POST-IRRADIATION
I
•
_ I \ / I V ~" 6( o
IRRADIATEDCOWS(4)
70 I
;,
tl)
///./I, N
NON-IRRADIATED
Io
.
~ o " " " /o--o / / ~ o~,
/
80 j / ~
%
945
CATTLE
I
12
FIG. 2. Comparative secretion of orally administered I TM into the milk of nonirradiated and gamma lethally irradiated dairy cows. The estimated total-body activity for Na ~ at the time the neutron treatment was terminated was estimated to be between 1 and 2 me. Since the first measurement for Na ~ in plasma was made several hours after the animals were removed from the reactor, induced radioactive elements of very short half-life would not have been detected. DISCUSSION
The gamma and neutron irradiations received by the animals in this study were not necessarily representative of the broad range of total dosage, dose rate, and combined gamma-neutron doses to which accidentally exposed animals may be subjected. An attempt was made to control the total dose at 650-675 fads of either gamma or neutrons plus gamma irradiation; however, Cows 5 and 6 received more and Cow 7 less than this amount. In addition to total dose, rate at which the dose is delivered is recognized as a factor in response of animals to gamma irradiation (2). A t ]east one report indicates that the lethal dose level for neutron irradiation is independent of dose rate under some conditions (5). A paucity of information exists concerning the effects of combined gamma-neutron doses. One difficulty in interpretation of the gamma versus neutron irradiation data reported here lies in the fact that similar tad doses were given in 21.8 and 0.43 hr, respectively (Table 1). The differences may be due to the effects of gamma versus neutron irradiation or may be due to the dose rate discrepancy (or both). In the event of a nuclear release, it seems probable that the area contaminated with highlevel gamma radiation will far exceed the area covered by neutron radiation. In addition, the
:Y,
o......o
/
~/~
\./ o~° --'°,. ~0
"/X
\o.....o~O---o
GAMMALETHALLY IRRADIATEDCOWS(4)
' ;'
;
DAYS POST-IRRADIATION FIG. 3. Comparative secretion of orally administered Sr s9 into the milk of nonirradiated and gamma lethally irradiated dairy cows. neutron radiation will be of short duration and will coincide to a large extent with the blast and thermal area in nuclear explosives. It appears that gamma radiation represents the condition under which the greatest number of animals will be exposed. The salvage of animal and animal product for human food should, therefore, be greatest in the gamma exposure area. I t is apparent that the carcasses of either neutron or gamma lethally irradiated animals can be salvaged for food if slaughtered shortly after exposure. Many of these animals in the exposure range studied in this investigation will be satisfactoi T for slaughter for a period of at least 12 days before bacterial infections begin and elevated temperatures are evident. Those animals receiving predominantly neutron irradiations would not maintain a constant weight during this tinle, due to a lack of appetite, and would produce only a small amount of milk. Those animals exposed to lethal levels of gamma irradiation could be used for milk production for a period of up to 12 days and still have a usable carcass. There is no indication that either strontium or iodine is passed more readily into milk as the result o£ lethal doses of gamma irradiation. On the contrary, in these investigations significantly less of these two fission products was passed into the milk of the gamma-treated cows versus the nonirradiated control animals. Since lethal irradiation did not result in an increased seeretion rate of iodine and strontium into milk, it would be expected that sublethally irradiated animals would respond in a sbnilar manner.
946
R. G. CRAGLE ET AL
REFEREI~CES (1) AUXlER, J. A. 1965. The Health Physics Research Reactor. Health Physics, 11: 89. (2) BATEMAN, J. L., BOND, V. P., A N D ROBERTsoN, J. S. 1962. Dose-Rate Dependence of Early Radiation Effects in Small Mammals. Radiology, 79: 1008. (3) BRowN, D. G., THOMAS, R. E., JONES, L. P., CROSS, F. H., AND SAS•ORE, D. P. 1961. Lethal Dose Studies with Cattle Exposed to Whole-Body Co~ Gamma Radiation. Radiation Research, 15:675. (4) LUNDIN, M. I. 1962. Health Physics Research
Reactor Hazards Summary, Oak Ridge National Laboratory Report 3248. August 24. (5) SPAULDING, J. F., AND SAYEG, J-. A. 1963. Dose Rate Effects on Lethality of Mice Exposed to Fission Neutrons (Abstract). I A E A Sympos. Biological Effects of Neutron Irradiation, Brookhaven National Laboratory. October 7-11. (6) WILDIIqG, J. L., RUST, J. H., AND SIMOI~S, C. S. 1952. A Multi-curie Irradiation Site for Exposure of Large Animals to WholeBody Gamma Irradiation. Nucleonics, 10: 36.