SWRHL-39r
131
I DAIRY COW UPTAKE STUDIES USING A SUBMICROMETER
SYNTHETIC DRY AEROSOL (PROJECT SIP)
by
Benjamin J. Mason, Stuart C. Black, and Delbert S. Earth
Radiological Research
Southwestern Radiological Health Laboratory
ENVIRONMENTAL PROTECTION AGENCY
Published March 1971
This study performed under a Memorandum of
Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
-------
This report was prepared as an account of work sponsored
by the United States Government. Neither the United States
nor the United States Atomic Energy Commission, nor any
of their employees, nor any of their contractors, sub-
contractors, or their employees, makes any warranty,
express or implied, or assumes any legal liability or
responsibility for the accuracy, completeness or usefulness
of any information, apparatus, product or process disclosed,
or represents that its use would not infringe privately
owned rights.
Available from the National Technical Information Service,
U. S. Department of Commerce,
Springfield, VA, 22151
Price: Paper copy $3.00; microfiche $.95.
012
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SWRHL-39r
131
I DAIRY COW UPTAKE STUDIES USING A SUBMICROMETER
SYNTHETIC DRY AEROSOL (PROJECT SIP)
by
Benjamin J. Mason, Stuart C. Black, and Delbert S. Barth
Radiological Research
Southwestern Radiological Health Laboratory*
ENVIRONMENTAL PROTECTION AGENCY
Published March 1971
This study performed under a Memorandum of
Understanding (No. SF 54 373)
for the
U.S. ATOMIC ENERGY COMMISSION
*Formerly part of U. S. Department of Health, Education, and Welfare,
Public Health Service, Environmental Health Service, Environmental
Control Administration, Bureau of Radiological Health.
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ABSTRACT
This report covers the fourth controlled release study conducted by
Radiological Research in a continuing program to define the mecha-
nisms associated with the overall transfer of radioiodines from the
environment to cow's milk.
A I labelled aerosol of submicrometer size was released over a
pasture and a corral containing 18 dairy cows. Six of the cows had
hay in mangers for their consumption. Another group of six was fed
green chop from the contaminated pasture while the remaining six cows
received no other contaminated material. The pasture was contaminated
to a level of 1.13 (iCi/kg, and cows fed green chop from the pasture
secreted a peak level of .07 (aCi/liter in milk. The effective half-
life of I in milk during ingestion of contaminated forage was
5.2 + 0.85 days which was nearly twice as long as the effective half-
lives in previous experiments using aerosols of larger particle size.
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TABLE OF CONTENTS
ABSTRACT i
TABLE OF CONTENTS ti
LIST OF TABLES iii
LIST OF FIGURES iv
ABBREVIATIONS AND DEFINITIONS v
I. INTRODUCTION 1
II. PROCEDURES
A. EXPERIMENTAL DESIGN 3
B. STUDY AREA 5
C. AEROSOL GENERATION AND MEASUREMENT 5
D. METEOROLOGICAL DATA COLLECTION 8
E. AGROLOGY STUDY AREA 9
F. SAMPLING TECHNIQUES 9
G. SAMPLE ANALYSIS 11
III. RESULTS AND DISCUSSION
A. AEROSOL DEPOSITION 12
B. VEGETATION CONTAMINATION 15
C. FORAGE CONTAMINATION 18
131
D. I ACTIVITY IN MILK 19
E. COMPARISON OF RESULTS WITH OTHER AEROSOL 26
EXPERIMENTS
IV. CONCLUSIONS 30
REFERENCES 31
DISTRIBUTION
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LIST OF TABLES
Table 1. Groups of Cows and Feeding Schedule.
Table 2. System Efficiency and Minimum Sensitivity for 131I.
Table 3. Analysis of Variance of 131I Contamination of the
Vegetation Study Area.
Table 4. Particle Size Distribution for Project SIP.
Table 5. 131I Activity on Air Sampler Components and
Deposition Velocities.
Table 6. 131I Activity in Green Chop Forage.
Table 7. Group I Milk Data.
Table 8. Group II Milk Data.
Table 9. Group III Milk Data.
Table 10. Summary of Milk Data from Aerosol Experiments.
4
11
15
16
17
19
22
23
25
27
iii
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LIST OF FIGURES
Figure 1. General Farm Layout for Project SIP. 6
Figure 2. Detailed Plan of Project SIP Layout. 7
Figure 3. Layout of the Agrology Study Vegetation Plots— n
Project SIP.
Figure 4. 131I Activity Isopleths from Planchet Data. 13
Figure 5. Planchet Rack Data and Deposition Vectors for the .,
SIP Aerosol.
Figure 6. Average 131I Concentration in Milk from the Three „_
Groups of Cows.
Figure 7. Milk/Forage Ratio vs. Particle Size (CMC) for the „„
Three Aerosol Experiments.
IV
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ABBREVIATIONS AND DEFINITIONS
CMD - count median diameter. The diameter of those particles in the
size-frequency table at the point where the cumulative count is
50 percent of the total number of particles counted.
MMD - mass median diameter. As above, but based on mass rather than
count.
CT - geometric standard deviation. The ratio of the 84 percent size
to the 50 percent size.
I, - physical half-life. The decrease in activity caused by radio-
2 active decay.
T, - biological half-life. Decrease of radioactivity in living
systems due to biological effects.
T - effective half-life. Decrease of radioactivity caused by a
e combination of T,, T, and other loss processes.
i b
QO - indicates a copyrighted name for a commercial product.
Green chop - fresh forage cut from a pasture by machine then placed
in the cow's manger.
Milk/Forage Ratio - the peak average concentration in milk (pCi/liter)
divided by the peak average concentration in
forage (pCi/kg).
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INTRODUCTION
The Radiological Research Program(RRP) in the Southwestern Radiological Health
Laboratory utilizes controlled releases of a simulated fallout as one
means of evaluating the passage of radioiodine through the air-forage-
"cow-milk-man food chain. Prior to the release discussed in this report,
RRP had conducted two releases using dry aerosols (1, 2) and one release
using an aerosol mist (3). The dry aerosols utilized I tagged diato-
maceous earth particles with a CMD greater than one micrometer. An
evaluation of the results of these two dry aerosol releases, code named
Hayseed (1), and Alfalfa (2), suggested that valuable information could
be obtained by conducting an experiment which utilized an aerosol particle
with a CMD of less than one micrometer.
This experiment, code named SIP*, was designed to accomplish the follow-
ing objectives:
131
1. To measure the deposition and retention of I on growing alfalfa
as a result of dissemination in the form of a dry aerosol with a
CMD of less than one micrometer.
2. To measure the secretion of I in the milk from a group of dairy
cows fed contaminated alfalfa green chop after first being exposed
to the aerosol cloud. (Simulated summer feeding practices.)
3. To measure the secretion of I in the milk from a group of dairy
cows given a single feeding of contaminated hay while being exposed
to the aerosol cloud. (Simulated winter feeding practice where
the hay supply is protected.)
4. To measure milk secretion of I from a group of dairy cows exposed
to the aerosol cloud but not fed contaminated forage (air uptake).
* an acronym for Submicrometer Iodine Particle
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In the Great Basin, two of the primary sources of cattle feed are hay
and fresh alfalfa green chop. Those dairies that feed green chop
during the summer growing season normally use hay as a supplement to
this fresh feed (4). These same dairies usually feed alfalfa hay
during the winter months.
Comparisons of the results of objectives 2 and 3 should aid in
determining the differences between I levels in milk from dairy
cows fed under a simulated winter feeding plan (i.e., single contami-
nated hay feeding) and in milk from cows fed under a simulated summer
feeding plan (i.e., green chop from a contaminated pasture, plus hay).
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PROCEDURES
A. Experimental Design
The experimental design for Project SIP was such that the only difference
between the groups of cows was the type of forage which was fed. Table 1
shows the three treatments evaluated in this study, the cows assigned to
the groups and the amounts of feed given to cows.
The assignment of cows to each group was based on milk production and
days of lactation. There was a bias in selecting the cows for Group II
in that several of the higher producers were placed in this group. This
was done because milk from this group was required not only for the study
presented in this report, but also for an ancillary study which is
reported elsewhere (5). The milk production of the Group II cows dropped
slightly and the Group I and III cows increased slightly between the
time assignments were made and the beginning of the experiment. This
change adjusted the average production per group so that there was no
significant difference among groups as determined by Analysis of Variance
(AOV).
About two hours prior to the release of the aerosol, all 18 cows were
milked then placed in a pen erected downwind from the aerosol generators.
The Group I cows were placed in a pen equipped with stanchions and a
manger in which was placed 75 kg of hay.
This provided a feeding station similar to those encountered in the
off-site area at the time of a radioactive cloud passage. The cows
were allowed to feed in the manger starting two minutes prior to release
and were left there until approximately 65 kg of the hay had been con-
sumed. (All that remained was stem material and loose leaves.) The
cows were decontaminated approximately 11-1/2 hours after the release,
placed in a separate corral and fed alfalfa hay according to the
schedule in Table 1. The Group II and Group III cows were placed in a
pen adjacent to the Group I cows. These animals were not provided with
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Table 1. Groups of Cows and Feeding Schedule
Group
Cow No.
Type of Feed
Remarks
I 2, 18, 36, Contaminated hay in field
"Winter" 47, 17, 87 manger on D-day. Uncon-
taminated hay during rest
of the experiment. Hay
fed free choice. Approxi-
mately 10 kg per feeding.
Cows received no green chop from
30 May through 16 June 1967.
II
"Summer"
11, 16, 28,
35, 45, 83
20 kg contaminated alfalfa
green chop in A.M. - 10 kg
uncontaminated hay in P.M.
Cows received contaminated green
chop Land No. 5 - 6 June to 12 June.
Land No. 6 - 13 June to 16 June 1967.
Ill 12, 25, 27, Approximately 20 kg uncon-
"Control" 29, 39, 48 taminated alfalfa green chop
in A.M. and 10 kg uncontami-
nated hay in P.M.
Cows received green chop harvested
from Land No. 1.
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forage and were removed from the pens approximately four hours after
the release. They were brought to the decontamination station, washed,
then led to their assigned positions. The Group II cows were placed
in individual pens and fed green chop from the contaminated pasture
for ten days according to the schedule in Table 1. The Group III cows
were placed in a separate corral and fed according to the schedule in
Table 1.
The first milking of all groups was at 1500 hours on 6 June 1967 or
about 13 hours after the aerosol release. Procedures for handling the
feed, for milking and for animal care are outlined in SWRHL-55r (6).
B. Study Area
The study area for this experiment was located in Lands 5, 6, and 7
of the Environmental Protection Agency's Experimental Farm, Area 15, Nevada
Test Site. Figure 1 shows the overall layout of the study area at the
time of the release. Figure 2 is a detailed drawing showing the loca-
tion of the air samplers, fallout collectors, plots, pens, etc.
C. Aerosol Generation and Measurement
The release of the aerosol was essentially the same as that used in
Projects Hayseed (1) and Alfalfa (2). Basically the method involves
the generation of a diatomaceous earth aerosol which has been ground,
131
sieved and tagged with I. The generation was accomplished by a
line of 20 generators spaced at an interval of 4.75 meters along a
line 7.5 meters upwind from the leading edge of the test field with
the outlet tube of the generators 46 cm. above the ground. The aerosol
was transported across the field by the normal drainage winds occurring
at the farm.
Stainless steel 4.5-inch planchets coated with a non-setting alkyd resin
were spaced at 7.5-meter intervals over a 60-by-22.5-meter section of
the test field at a height even with the top of the growing alfalfa
(approximately 46 cm. above the ground). Data from these were used
to determine the deposition isopleths and as part of the deposition
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Barn, Hay, Shed
and Corrals
4. •<- Gate
Land Number Contro1 Foraqe
y//////////y///////////////////////////A
A Hurricane Air Sampler
° Special Projects Section Air Sampler
SCALE: 1" = 60 Meters
Figure I. General Farm Layout for Project SIP
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90m
OOOOOOOOOOOOOOO
60m
21m
7.5m
7.5n
7.5i
O
Lateral 5
N
40.5m
5m
Agrology Studies
4m
Lateral 6
19m
O
1
Cow Pens
22m
D| JBiophysical Sampler
3m
O Planchet Rack
•Air Sampler (Gelman)
O Cascade Impactor
O Aerosol Generator
• Planchet
Figure 2. Detailed plan of Project SIP Layout
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velocity calculations. Additional planchets were placed in the
agrology study area to the rear of this section. Two racks containing
a series of horizontally and vertically oriented planchets, located
at ground, one- and two-meter levels, were placed at the rear of the
study area on either side of the cow pens. These special racks were
used both to determine the angle of deposition of the aerosol particles
and to determine whether or not the aerosol cloud remained close to
the ground.
Gelman Tempest air samplers were placed at various locations through-
out the plot and adjacent to the cow pens to measure airborne concen-
131
trations of I. These samplers contained Whatman 541 prefilters,
0 postfilters. Glass slides
(1 by 3 inches) were spaced evenly throughout the field and were used
to determine the size distribution of the deposited aerosol.
To measure the mass median diameter of the aerosol cloud, two Unico
cascade impactors were placed near the cow pens as shown in Figure 2.
D. Meteorological Data Collection
The particle size distribution expected for Project SIP was such that
the meteorological conditions required for aerosol release were
important. Evaluation of the results from Hayseed (1) and Alfalfa (2)
indicated that a wind speed of less than five miles per hour and a wind
direction with an azimuth somewhere between 315 and 15 degrees were
required if sufficient deposition was to be obtained on the experimental
area.
The various meteorological parameters which influence aerosol transport
and deposition were monitored by meteorological sensors located in
three fixed positions upwind from the line of generators. One station
was located midway and one station was located at each end of the line
of generators. The sensors were one meter above the ground level.
From continuous recordings, average values were derived of wind speed
and wind direction at two-minute intervals during and at 15-minute
intervals following the release. The temperature, relative humidity,
and precipitation were also recorded. In addition to these data,
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ambient temperature and the temperature gradient (AT 1-10 meter levels)
were also recorded.
E. Agrology Study Area
131
In order to adequately evaluate the T of the submicrometer I
particles on growing alfalfa, a sampling area of three blocks was
set up in the Agrology Study Area near the cow pens (Figure 2). Each
block consisted of sixteen one-square-meter plots as shown in Figure 3.
At each of eight sampling times, two randomly selected plot samples
were taken from each block. The sampling times were at 0800 hours
each day starting on the day of release and at 1, 2, 4, 6, 9, 14, and
20 days afterward. The samples were pressed into the standard vegeta-
tion geometry (1) and gamma counted for I. The results of the I
analyses were evaluated according to the Analysis of Variance presented
in Table 5 under the results section.
F. Sampling Techniques
The forage given to Group I cows was sampled by taking a composite
of grab samples at several points and depths along the length of the
manger. The feed for the Group II cows was sampled individually by
taking a composite of a grab sample from each of the four corners and
the bottom center of each of the plastic feed boxes. A number of grab
samples was taken from the feed bunkers used for Group III. The samples
taken from Group III provided a check on feed contamination from re-
suspension and other unknown releases of activity. The frequency of
all of these sample collections corresponded to the feeding periods.
The forage samples were placed in plastic bags, the bags sealed and
the samples transported to Sample Control where each sample was com-
pressed into a 500-milliliter plastic container of standard geometry.
This sample was then submitted for gamma analysis. The grain used as
a feed supplement was sampled once daily. This single 500-ml. sample
was taken from the grain storage bin inside the milking room.
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Block 1
Block 2
Block 3
N
I
4
1
i
m
1
1
5
9
13
2
A
3
4
16
>_
*
1
16
16
Figure 3 Layout of the Agrology Study Vegetation Plots - Project SIP
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A one-gallon composite sample of water was collected daily from each
group. The composite sample for Group II was made up of equal amounts
of water from each cow's watering cup. The sample was submitted for
(R\
analysis in a plastic Cubitainer^ .
One-gallon samples of milk were collected at each milking. These
samples were also submitted for analysis in plastic Cubitainers. At
the time of collection ten milliliters of 37 percent formaldehyde
preservative were added to each milk sample.
G. Sample Analysis
131,
All of the planchets and air filters were analyzed for " I by using
a system consisting of opposed 4-by 9-inch Nal (Tl) crystals and a
400-channel analyzer. This system has been described in detail in
earlier reports (1, 2). The minimum sensitivities for the various
geometries are outlined in Table 2.
Table 2. System Efficiency and Minimum Sensitivity for
131.
Sample Type
Container
Minimum
Efficiency Sensitivity*
Milk and Water
Grain
Hay
Green Chop
Charcoal
(from air sampler)
Filter paper
Fallout planchet
4-liter Cubitainer
400 ml. plastic container
400 ml. plastic container
400 ml. plastic container
250 ml. plastic container
100 ml. plastic container
100 ml. plastic container
17.37. 10+5 pCi/1
27.8% 80+10 pCi/kg
28.17» 100+15 pCi/kg
34.87c 80+10 pCi/kg
27.87o 30+5 pCi/sample
48.07» 15+5 pCi/sample
48.07» 15+5 pCi/sample
* Based on a 40-minute count
Milk, water, grain, and vegetation samples were submitted to the Laboratory's
Technical Services group for analysis. The analysis was done on systems
using 4-by 4-inch Nal (Tl) crystals coupled to TMC Model 404-C pulse height
analyzers calibrated for energies of 0-2 MeV.
11
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RESULTS AND DISCUSSION
A. Aerosol Deposition
The release of the aerosol began at 0150 PDT, 6 June 1967, and was
complete after an average generation time of approximately 22 minutes.
During this time the wind was blowing from 309 degrees true azimuth
at an average speed of three miles per hour. The temperature for
o
this period averaged 39.4 F. and the average relative humidity was
58.6 percent.
Aerosol deposition across the test grid as measured by fallout
2
planchets showed an average of 1.63 ^Ci/m . Of the total amount of
51.78 mCi released, 4.3 percent was deposited on the study area.
The isopleths drawn from the planchet data indicate that 96 percent
2
of the test grid was contaminated at levels from 1-3 fiCi/m and
2
the remaining 4 percent at a level of 4.5 /jCi/m (Figure 4).
2
In the Agrology Study Area the average deposition was 0.98 /;Ci/m .
Data obtained from the special planchet racks, together with the
respective "deposition vectors" are shown graphically in Figure 5.
The "deposition vector" is defined as the resultant of the two vectors
calculated from the activity on the horizontal and vertical planchets.
These data demonstrate that the cloud was more concentrated below
2 meters. The vectors show that the particles were being deposited
in a nearly vertical mode close to the ground, whileat higher
elevations the horizontal vector became stronger, probably due to
the effect of winds.
The planchet rack data indicate that the active cloud remained close
to the ground during transport across the experimental area. The
uniformity of the individual values between the two planchet racks
is remarkable.
12
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Project SIP Study Area
Activities (yCi/m2)
131
Cloud Travel
Figure 4. I Activity Isopleths from Planchet Data
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Rack No.
Planchet Height
Rack No. 2
1.96
(1.69
2 m
2.19
10.8
I m
Deposition Vector
9.62
9.62
4.44
9.82
Surface
9.36
= Vertical planchet orientation
Figure 5.
= Horizontal planchet orientation
2
Numbers indicate deposition in yCi/m
Planchet Rack Data and Deposition Vectors for
the SIP Aerosol
14
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Table 4 shows the cumulative size distribution of the aerosol particles.
These data show that the CMD of the cumulative distribution was
approximately 0.13 micrometers with a °g of 4.1. The two Unico cascade
impactors located in the test area indicated an HMD of 1 and 2.6
micrometers respectively.
Table 5 shows the activity collected on each air sampler component
and the deposition velocities, calculated from these data plus the
planchet data. An average of approximately 70 percent of the activity
was collected on the prefilters which had a mean pore size of from
3.4 to 5 micrometers.
B. Vegetation Contamination
The results of the Analysis of Variance for the radioactivity on
the growing alfalfa are presented in Table 3.
TABLE 3. Analysis of Variance of 131I Contamination
of the Vegetation Study Area
Source of Variation df F
Block
Time
Block x Time
Error
TOTAL
2
7
14
24
47
3.27
67.77**
1.36
**Significant at 1% Confidence Level.
This analysis indicates that the deposition over the vegetation study
area was quite uniform, that there was no difference in the effect of
time on the different blocks and that the only significant variable
was decay with time. Using the data from all three blocks, T 's
were calculated for the pasture. This calculation showed a two-phase
loss of 131I from the plants. The first phase, lasting 3-4 days,
reduced the incident contamination by about 50%. This phase showed
15
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Table 4 . Particle size distribution for the
aerosol released during Project SIP
Size
dmn)
<0.03
0.03
0.05
0.08
0.11
0.13
0.16
0.19
0.21
0.24
0.27
0.29
0.32
0.34
0.37
0.40
0.42
0.48
0.50
0.53
0.56
0.58
0.61
*Ref ers
Count
4959
3002
1936
1827
979
2001
914
761
935
783
3632
392
283
261
87
348
87
87
65
979
65
87
65
Cumulative
Count*
4959
7961
9897
11724
12703
14704
15618
16379
17314
18097
21729
22121
22404
22665
22752
23100
23187
23274
23339
24318
24383
24470
24535
to amount ^. stated
Cumulative
Per Cent*
17.4
27.9
34_6
41.0
44.5
51.5
54.7
57,3
60.6
63.3
76.1
77.4
78.4
79.3
79.6
80.9
81.2
81.5
81.7
85.1
85.3
85.6
85.9
size.
Size
(u)
0.64
0.66
0.72
0.80
0.82
0.87
0,93
0.98
1.01
1.06
1.33
1.80
2.90
3.90
4.90
10.10
15.60
20.80
24.70
29.90
35.10
40,30
45.50
Count
65
131
22
479
22
44
44
44
22
326
371
321
767
206
72
357
169
70
36
49
36
27
73
Cumulative
Count*
24600
24731
24753
25232
25254
25298
25342
25386
25408
25734
26105
26426
27193
27399
27481
27838
28007
28077
28113
28J62
28198
28225
28298
Cumulative
Per Cent*
86.1
86.6
86.6
88.3
88.4
88.5
88.7
88.9
88.9
90.1
91.4
92.5
95.2
95.9
96.2
97.4
98.0
98.3
98.4
98.6
98.7
98.8
99.0
16
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131
TABLE 5. I Activity on Air Sampler Components
and Deposition Velocities
Sampler
Number
1
2
3
4
5
6
7
8
Whatman
Activity
(nCi)
427
649
521
650
512
176
909
434
Charcoal
Activity
(nCi)
263
270
163
241
168
63
130
136
Microsorban
Activity
(nCi)
3.4
12.9
5.4
8.6
7.0
8.1
5.9
5.6
Deposition*
Velocity
cm/ sec
1.21
1.69
0.55
0.71
0.54
1.47
0.46
0.71
2 3
* yCi/m from planchet divided by the integrated air concentration in pCi-sec/m
17
-------
an average T of three days. The second phase of the activity curve
had a 6.5-day half-life.
131
The T for this second phase did not reach the 8-day T, ,_ of I
e i/ i
probably because of growth of the alfalfa and also because of some
131
additional loss of I from the plants. However, plant growth
was the most likely cause of the shortened half-life. This ob-
servation is borne out by the fact that irrigations on D + 6,
D + 14 and D + 18 had no effect upon the activity levels. If
particles were still being lost from the plant this application of
water should have had some influence upon the activity levels.
This observation is also supported by results of an ancillary study
conducted with Project SIP- In this study, samples of the vegetation
®
were vigorously washed in a 0.1% Joy solution. After D + 4 this
washing had no effect upon the activity levels in the vegetation.
Thus the I had either become more tightly bound to or had been
absorbed by the plant. Therefore, the most likely cause of the
reduction in contamination during the second phase is considered
to be the growth of the plants.
C. Forage Contamination
In previous releases, (1, 2) the I activity in the forage fed to
the dairy cattle followed a different decay scheme than that in the
growing alfalfa plot. This same observation can be made with the
131
green chop fed during Project SIP. Table 6 shows the daily I
activity in the green chop fed to Group II cows. The activity had
a calculated T of 4.1 days. The shorter effective half-life of
green chop compared to that of the undisturbed growing alfalfa is
considered to be a result of the dislodging of the contaminating
particles during chopping and handling of the forage.
18
-------
131
TABLE 6. I Activity in Green Chop Forage
131
I Activity
Date
6/6
6/7
6/8
6/9
6/10
6/11
6/12
6/13
6/14
6/15
6/16
Hour
0900
0700
0850
0800
0940
0900
0830
0830
0850
0800
0800
uCi/kg
1.02±0.21
1.13±0.06
0.86±0.14
0.68±0.09
0.59±0.06
0.51±0.07
0.69±0.22
0.27±0.03
0.27±0.04
0.26±0.03
0.24±0.02
In some of the grain and water samples I was detected at levels
slightly above the minimum detectable activity. At no time were
these additional sources of activity high enough to materially in-
fluence the results, i.e., <0.17» of the total intake.
D. I Activity in the Milk
131
The average levels of I found in the milk at each milking are
shown in Figure 6. As can be seen from the curves, the I levels
in the milk from cows of Groups I and III showed the characteristic
early peak resulting from air uptake. The Group I cows had a
higher level of activity in their milk as a result of the longer
time in the contaminated area and also as a result of eating the
hay which was in their feed bins during aerosol generation. The
effect of the uptake from the hay most likely caused the broadening
of the peak seen in the data from the first two milkings.
In Groups I and III the activity in the milk began to drop immedi-
ately after the first milking. The curves of these data show
T 's of 1.05 and 1.52 days, respectively. The curve for the hay
cows (Group I) follows a pattern similar to that seen in our
19
-------
-------
previous studies after hay feeding was terminated. In both Group I
and Group III, the peak milk values occurred at the first milking
after contamination. The peak for similar treatments during
Hayseed and Alfalfa occurred at one day.
The Group II cows exhibited a triphase curve that was similar to
that seen in our earlier controlled releases where green chop was
fed (1, 2). The half-life during feeding, however, was longer than
that seen in those earlier studies. The T value of 5.2 days is
e
approximately double that for Alfalfa and Hayseed. The peak milk
values in the Group II milk occurred at 1.6 days.
In all three groups, the short effective half-life components of
the milk secretion curves (T approximately one day) lasted about
five days then was followed by a component with a T of 2-4 days.
131
Apparently the I on these small particles was retained on the
131
forage longer than the I from the larger aerosol particles.
The fact that the T of the "after feeding" portion of the milk
curves all exhibited half-lives in excess of one day, as compared
to those of Alfalfa and Hayseed where the half-lives were less
than one day, suggests that the I on these small particles
was retained in the cow longer or that there were some undetected
differences in iodine metabolism among the three experiments.
The average milk data for all three cow groups and standard devia-
tions are shown in Tables 7-9.
An estimate of the milk/forage ratio for the group eating hay con-
taminated in their manger can be made by correcting for inhalation.
131
If the average peak I concentration in the milk of Group III
cows is subtracted from that of the Group I cows, then the remainder
2
should be due to ingestion of contaminated hay. Subtracting 1.17 x 10
3 3
from 4.32 x 10 leaves 3.15 x 10 pCi/liter due to ingestion of the
hay. Since Group I cows ingested hay which had 7.98 x 10 pCi/kg
of I, the milk/forage ratio becomes .040. Similarly, since each
cow ingested about 11 kg of the hay and since the average total
secretion of I in the milk of these cows was 2.11 x 10 pCi
21
-------
Collec t ion
Date Hour
6/ 6
6/ 7
6/ 7
6/ 8
6/ 8
6/ 9
6/ 9
6/10
6/10
6/11
6/11
6/12
6/12
6/13
6/13
6/14
6/14
6/15
6/15
6/16
6/16
1448
617
1542
651
1525
654
1522
717
1538
712
1527
717
1554
645
1522
642
1528
725
1530
649
1532
Days
Lapsed
EH-
EH-
Ett-
EH-
EH-
D+
EH-
D+
EH-
EH-
D+
D+
D+
EH-
EH-
D+
EH-
EH-
EH-
D+
D+
0.61
1.26
1.65
2.28
2.64
3.28
3.64
4.30
4.65
5.30
5.64
6.30
6.66
7 .28
7 .64
8.27
8.64
9.30
9.64
10.28
10.64
Table 7. Group I Milk Data
I-nCi/Liter Liters
Mean Sigma Mean Sigma
4.32
3.72
3.00
1.58
1.09
0.651
0.512
0.336
0.291
0.184
0.72
0.137
0.144
.099
.094
.070
.062
.054
.048
.042
.048
0.895
1.11
0.935
0.669
0.481
0.317
0.282
0.149
0.136
.082
.058
.061
.074
.054
.040
.033
.025
.023
.016
.013
.019
13.6
14.1
8.6
12.2
8.8
13.6
8.8
13.6
8.6
12.4
8.8
13.3
8.5
13.1
8.9
12.9
9.1
13.3
8.5
12.0
9.1
5.6
4.7
3.5
4.9
3.0
4.1
3.3
3.5
3.8
3.6
3.4
4.3
4.0
5.0
2.1
5.3
2.6
4.6
3.5
4.3
3.1
Total
Mean
62.5
56.5
27.9
21.4
10.6
5.56
4.76
4.75
2.63
2.30
1.57
1.83
1.39
1.30
0.866
0.997
1.27
0.750
0.422
0.505
0.452
nCi
Sigma
33.7
33.1
19.0
16.0
8.35
3.29
3.96
3.24
2.29
1.36
1.07
1.14
1.45
1.02
0.530
0.885
1.68
0.477
0.286
0.269
0.288
-------
Table 8. Group II Milk Data
NJ
LO
Collection
Date Hour
6/ 6
6/ 7
6/ 7
6/ 8
6/ 8
6/ 9
6/ 9
6/10
6/10
6/11
6/11
6/12
6/12
6/13
6/13
6/14
6/14
6/15
6/15
6/16
6/16
1519
654
1607
722
1556
723
1548
749
1602
749
1552
747
1630
722
1552
715
1556
751
1600
721
1602
Days
Lapsed
D+
D4-
D+
D+
D4-
Df
D4-
IH-
D4-
D4-
D+
D4-
IH-
D4-
D+
Df
D^
D4-
D+
DH-
D+
0.63
1.28
1.67
2.30
2.66
3.30
3.65
4.32
4.66
5.32
5.66
6.32
6.68
7.30
7.66
8.30
8.66
9.32
9.66
10.30
10.66
I-nCi/Liter
Mean Sigma
24.5
33.3
69.5
40.8
51.7
37.8
58.3
35.2
47.7
30.6
51.1
31.6
49.2
42.2
46.5
28.2
33.9
16.6
18.9
16.2
19.9
11.7
8.99
16.2
9.60
15.8
14.2
20.8
11.4
18.5
11.4
21.4
11.7
18.9
14.7
15.8
12.5
15.9
5.24
8.97
6.56
7.83
Liters
Mean S igma
14.5
14.9
8.8
15.3
9.3
16.0
8.2
15.8
8.8
16.0
9.1
16.0
8.9
14.8
7.9
12.5
8.0
14.0
7.7
14.1
7.2
4.8
5.8
2.9
5.6
4.5
6.5
3.4
5.3
4.0
6.4
3.7
6.0
3.6
5.2
2.4
6.2
3.8
8.3
4.3
6.6
3.6
Total nCi
Mean S igma
361
507
631
645
483
621
492
559
433
492
446
506
435
651
377
336
258
231
155
233
153
217
266
286
346
289
370
286
238
272
243
186
233
213
353
176
179
124
148
112
134
100
-------
Table 8. Group II Milk Data (continued)
Collection
Date Hour
6/17
6/17
6/18
6/18
6/19
6/19
6/20
6/20
6/21
6/21
6/22
6/22
6/23
6/24
6/24
6/25
6/25
6/26
6/26
6/27
6/27
6/28
722
1545
731
1556
724
1541
713
1547
713
1531
642
1515
1415
615
1515
615
1515
628
1518
627
1516
624
Days
Lapsed
D+
D+
D+
D4-
EH-
D+
EH-
EH-
EH-
EH-
D4-
IH-
EH-
EH-
EH-
D4-
EH-
EH-
EH-
EH-
EH-
D+
11.30
11.65
12.31
12.66
13.30
13.65
14.30
14.65
15.30
15.64
16.27
16.63
17.59
18.26
18.63
19.26
19.63
20.27
20.63
21.26
21.63
22.26
iJ1I-nCi/Liter
Mean Sigma
11.9
7.65
3.86
3.02
2.43
1.92
1.42
0.918
0.634
0.659
0.482
0.406
0.366
0.427
0.372
0.275
0.269
0.260
0.251
0.188
0.180
0.156
4.87
3.07
1.16
0.986
0.872
0.725
0.837
0.351
0.274
0.395
0.261
0.269
0.267
0.272
0.108
0.152
0.136
0.134
0.121
0.116
0.105
.072
Liters
Mean Sigma
14.5
8.6
15.3
7.5
13.6
7.6
14.2
8.3
13.5
7.5
13.7
6.3
17.7
12.1
6.9
15.0
6.5
13.9
7.9
13.9
6.6
13.9
5.6
4.2
6.2
3.1
4.5
3.1
5.3
3.6
6.1
2.2
4.9
2.7
7.8
5.2
2.8
6.8
2.5
5.3
2.6
5.4
3.2
4.5
Total nCi
Mean Sigma
177
67.7
61.2
22.9
34.5
15.4
23.5
7.92
8.56
5 .06
6.46
2.26
6,32
4.74
2.47
3.95
1.74
3.44
1.96
2 .48
1.22
2.13
95.5
44.5
32.4
12.1
19.7
10.2
24.2
5 .40
4.77
3.26
3 .72
1.25
5.21
2.51
0 .914
2 . 18
0 .920
1.70
0 .972
1 43
±. • I~T~/
0.799
1.00
-------
Collection
Date Hour
6/ 6
6/ 7
6/ 7
6/ 8
6/ 8
6/ 9
6/ 9
6/10
6/10
6/11
6/11
6/12
6/12
6/13
6/13
6/14
6/14
6/15
6/15
6/16
6/16
1417
545
1507
622
1502
627
1500
649
1517
643
1503
646
1515
607
1445
612
1504
654
1503
613
1507
Days
Lapsed
EH-
Df
Df
D+
D4-
EH-
D4-
Df
EH-
D+
Df
D+
EH-
EH-
D+
Df
D+
IH-
EH-
EH-
EH-
0.59
1.23
1.63
2.26
2.62
3.26
3.62
4.28
4.63
5.28
5.62
6.28
6.63
7.25
7.61
8.25
8.62
9.28
9.62
10.25
10.63
Table 9. Group III Milk
131
I-nCi/Liter
Mean Sigma
1.17
0.771
0.672
0.427
0.335
0.245
0.227
0.192
0.155
0.146
0.151
0.133
0.115
.090
.070
.064
.065
.063
.073
.065
.074
0.923
0.560
0.496
0.334
0.236
0.119
0.109
.085
.071
.090
0.115
.079
.072
.043
.037
.034
.031
.032
.041
.030
.034
Data
Liters
Mean Sigma
13.2
12.5
7.6
11.9
8.1
12.8
7.9
13.0
7.7
12.9
6.8
12.7
7.9
11.6
7.1
12.2
7.4
11.9
6.5
11.3
8.5
6.2
5.5
3.3
5.8
3.8
6.2
4.1
6.2
3.8
5.9
3.5
6.0
3.6
5.8
3.2
5.7
4.2
4.6
3.4
5.0
3.2
Total
Mean
14.5
8.81
4.77
4.47
2.40
3.03
1.72
2.39
1.24
1.81
1.05
1.67
.960
1.04
0.495
0.729
0.451
0.708
0.467
0.739
0.628
nCi
Sigma
13.0
6.08
3.29
3.07
.43
1.81
1.04
1.46
0.806
1.17
0.804
1.16
0.704
0.707
0.342
0.401
0.266
0.431
0.270
0.445
0.301
-------
(for 11 days), then the total percent in milk is calculated as 17.9.
This is a relatively high percentage and may be due to the continued
exposure to inhalation during their stay in the contaminated area.
This latter fact also casts some doubt on the .040 milk/forage ratio.
E. Comparison of Results with other Aerosol Experiments
Comparisons among the three aerosol experiments (Hayseed, Alfalfa
and SIP) are shown in Table 10. These data suggest several inter-
esting differences among the three experiments. It had been
postulated, from the results of Alfalfa, that the particle size
of the deposited material may have a direct bearing on the transfer
of radioiodine from forage to milk. A crude measure of this transfer
is the milk/forage ratio which appears to be larger for the SIP
experiment than for the previous two experiments. A graph of the
milk/forage ratio vs. particle size is shown in Fig. 7 for two types
of forage. The third point on the hay curves (Fig. 7) is missing
because in SIP the cows had only a single feeding, i.e., the hay
in the manger which was contaminated by the aerosol cloud, whereas
contaminated hay had been fed to the cows for several days in the
other two experiments.
In extrapolating this curve, it is reasonable to suppose that when
the iodine-containing particles get large enough, they will fall off
the forage and result in a zero milk/forage ratio. This should not
occur at particle sizes indicated by a linear extrapolation of the
curve to the right, therefor the line should curve here to approach the
abscissa more slowly. At smaller particle size, the line may extrapolate
toward the ordinate in several ways so a simple linear extrapolation is
shown. Milk/forage data from other experiments can be entered on this
line to indicate an "effective CMD" for the contaminating debris. Such
data from green-chop-fed cows at the Habbart farm following the Pike Event(7)
and at the Hiko farm following the Pin Stripe Event (8) yield an "effective
CMD" of .011 and .023 respectively, which are not unreasonable values.
26
-------
Table 10.
Summary of Milk Data from Aerosol Experiments
Experi-
ment
SIP
6/6/67
Alfalfa
6/21/66
Hayseed
10/4/65
Type
of
Intake
Air+GC
Air+ 1 hay
Air
GC
Hay
Air
GC
Hay
Air
Duration
of Inges-
tion Days
10
<1
9
8
6
6
Time of
Peak in
Milk Days
1.6
1st Milk
1st Milk
1.5
1.0
1st Milk
2
1
1st Milk
Te During
ingest ion
Days
5.2±0.8
-
2.5±0.2
8.2±1.3
-
3.0
2.7
-
Te After
Ingest ion
Days
1.15±0.06
1.05±0.06
1.52±0.1
0.9 ±0.2
0.9 ±0.1
0.9 ±0.38
<1
<1
0.8
Milk/
Forage
Ratio
.061
.040
.029
.069
-
.0078
.027
-
CMD of Total
Particles %
ium in Milk
0.13 7.6±3.4
17.9
2.0 12.5±7.8
15.2±6.2
23 2.1±0.7
6.3±3.3
Average Peak
Value in Milk
nCi/liter
69.5
4.3
1.2
109
40
2
22
12
0.6
-
-------
-Figure 7. Milk/Forage Ratio vs. particle size (CMD) for
the three aerosol experiments.
i Hayseed 23 urn
Alfalfa 2 um
SIP 0.13 um
iiWi'lk/1Fbr'age""£'roin""lJTKE
and PIN STRIPE
CMD
1.0
Particle Size
100
- micrometers
-------
A puzzling difference between the data of SIP and Alfalfa is in the
summary milk results for the green-chop-fed cows. In SIP both the
T during feeding and the milk/forage ratio were greater than in
Alfalfa yet the total percent secreted in milk was less for the
SIP cows. A possible explanation of this is that one cow was widely
variant from the average. Cow 12 was one of the green-chop-fed cows
131
during Alfalfa and secreted more than twice the percentage of I
in her milk than any other cow in the group. Excluding Cow 12, the
average percent secreted in milk of the group would have been 8.7%,
which is not much different from the SIP value.
A third difference, as already discussed, is the longer effective
half-life during ingestion in the milk of the green-chop-fed cows,
and the longer T after ingestion in the milk of all three groups
of cows. It seems unlikely that this would be an effect of particle
size only as once the iodine gets into the cow the particle that
carried it should be unimportant. A possible explanation is that
there were some undetected differences in the cows' metabolism
caused by the type of feed, season of the year, state of lactation
or some other factor. This remains to be explored in future experi-
ments .
29
-------
CONCLUSIONS
The objectives outlined in the introduction were met by this study.
Iodine-131 contaminated aerosol particles with a count median dia-
meter of less than 1 micrometer were deposited on and retained by
growing alfalfa forage. The I activity disappeared from the alfalfa
pasture with an initial effective half-life of approximately three days.
After three to four days the T changed to 6.5 days. This suggests that
the iodine on submicrometer particles was retained more tenaciously
than that on the larger particles used in our previous studies.
The I activity in milk from green-chop-fed cows (Group II) showed
a pattern similar to that seen in our earlier studies. The principal
difference was in the longer half-life during and after feeding.
A plot of the I activity in milk from cows which acquired
activity by being exposed to the aerosol during generation plus
a single feeding of contaminated hay (Group I) showed little
difference in shape from that of the cows exposed only to the
aerosol (Group III). The difference was due to the higher amount
of activity taken in by the Group I cows.
Comparisons between the Group I and Group II data indicate that
cattle exposed to I activity during a hay feeding regime similar
131
to that used herein would secrete about 2.2 percent of the I in
their milk compared to cows fed on green chop over a 10-day period,
provided conditions were similar to those encountered during Project
SIP. Group III cows (air intake only) secreted about 0.6 percent
of the I as the green-chop-fed cows.
The milk/forage ratios for the green-chop-fed cows from the three
aerosol experiments increased as the particle size decreased
suggesting that the particle size used in SIP acts more like the
debris deposited on dairy farms after the Pike and Pin Stripe
events than did the larger particle sizes used in Hayseed and
Alfalfa.
30
-------
REFERENCES
1. S. C. Black, D. S. Earth and R. E. Engel, I Dairy Cow Studies
Using a Synthetic Dry Aerosol (Project Hayseed), Southwestern
Radiological Health Laboratory, Las Vegas, NV Report SWRHL-28r
(to be published).
131
2. R. E. Stanley, S. C. Black and D. S. Earth, I Dairy Cow Studies
Using a Dry Aerosol (Project Alfalfa), Southwestern Radiological
Health Laboratory, Las Vegas, NV Report SWRHL-42r (August 1969).
131
3. R. L. Douglas, S. C. Black and D. S. Earth, I Transport Through
the Air-Forage-Cow-Milk System Using an Aerosol Mist (Project Rainout),
Southwestern Radiological Health Laboratory, Las Vegas, NV Report
SWRHL-43r (in press).
4. Pasture and Green Chop Feeding Practices in Nevada, Environmental
Surveillance Program, Southwestern Radiological Health Laboratory,
Las Vegas, NV Report SWRHL-40r (November 1968).
5. In Vivo Thyroid Uptake Study (unpublished report).
6. D. D. Smith and R. E. Engel, Progress Report for the Bioenvironmental
Research 5/22/64 Through 7/1/66 Part I: Experimental Dairy Herd,
Southwestern Radiological Health Laboratory, Las Vegas, NV Report
SWRHL-55r (March 1969).
7. D. S. Earth and J. G. Veater, Dairy Farm Radioiodine Study Following
the Pike Event, Southwestern Radiological Health Laboratory, Las Vegas,
NV Report TID-21764 (11/23/64).
8. D. S. Earth, R. E. Engel, S. C. Black and W. Shimoda, Dairy Farm Radio-
iodine Studies Following the Pin Stripe Event of April 25, 1966,
Southwestern Radiological Health Laboratory, Las Vegas, NV Report
SWRHL-41r (July 1969).
31
-------
DISTRIBUTION
1-20 SWRHL, Las Vegas, Nevada
21 Robert E. Miller, Manager, NVOO/AEC, Las Vegas, Nevada
22 Robert H. Thalgott, NVOO/AEC, Las Vegas, Nevada
23 A. Dean Thornbrough, NVOO/AEC, Las Vegas, Nevada
24 Henry G. Vermillion, NVOO/AEC, Las Vegas, Nevada
25 Robert R. Loux, NVOO/AEC, Las Vegas, Nevada
26 Donald W. Hendricks, NVOO/AEC, Las Vegas, Nevada
27 Elwood M. Douthett, NVOO/AEC, Las Vegas, Nevada
28 Jared J. Davis, NVOO/AEC, Las Vegas, Nevada
29 Ernest D. Campbell, NVOO/AEC, Las Vegas, Nevada
30 - 31 Technical Library, NVOO/AEC, Las Vegas, Nevada
32 Mail & Records, NVOO/AEC, Las Vegas, Nevada
33 Chief, NOB/DASA, NVOO/AEC, Las Vegas, Nevada
34 Martin B. Biles, DOS, USAEC, Washington, D. C.
35 Roy D. Maxwell, DOS, USAEC, Washington, D. C.
36 Assistant General Manager, DMA, USAEC, Washington, D. C.
37 Gordon C. Facer, DMA, USAEC, Washington, D. C.
38 John S. Kelly, DPNE, USAEC, Washington, D. C.
39 Fred J. Clark, Jr., DPNE, USAEC, Washington, D. C.
40 Daniel W. Wilson, Div. of Biology & Medicine, USAEC, Washington, D. C.
41 John R. Totter, DBM, USAEC, Washington, D. C.
42 Joseph J. Di Nunno, Office of Environmental Affairs, USAEC, Washington, D. C.
43 Philip Allen, ARL/NOAA, NVOO/AEC, Las Vegas, Nevada
44 Gilbert J. Ferber, ARL/NOAA, Silver Spring, Maryland
45 John S. Kirby-Smith, DBM, USAEC, Washington, D. C.
46 Charles L. Osterberg, DBM, USAEC, Washington, D. C.
47 Rudolph J. Engelmann, DBM, USAEC, Washington, D. C.
48 L. Joe Deal, BBM, USAEC, Washington, D. C.
49 Joseph A. Lieberman, Act.Comm.,Radiation Office, EPA, Rockville, Md.
50 William A. Mills, Act.Dir.,Div. of Research, Radiation Office, EPA, Rockville, Md.
-------
Distribution (continued)
51 - 52 Charles L. Weaver, Act.Dir., Div. of Surveillance & Inspection,
Radiation Office, Rockville, Md.
53 Bernd Kahn, Radiological Engineering Lab., EPA, Cincinnati, Ohio
54 Interim Regional Coordinator, Region IX, EPA, San Francisco, Calif.
55 Southeastern Radiological Health Lab., EPA, Montgomery, Alabama
56 William C. King, LRL, Mercury, Nevada
57 Bernard W. Shore, LRL, Livermore, Calif.
58 James E. Carothers, LRL, Livermore, Calif.
59 Roger E. Batzel, LRL, Livermore, Calif.
60 Lynn R. Anspaugh, LRL, Livermore, Calif.
61 Howard A. Tewes, LRL, Livermore, Calif.
62 Lawrence S. Germain, LRL, Livermore, Calif.
63 Paul L. Phelps, LRL, Livermore, Calif.
64 Harry J. Otway, LASL, Los Alamos, New Mexico
65 William E. Ogle, LASL, Los Alamos, New Mexico
66 William L. Langham, LASL, Los Alamos, New Mexico
67 Harry S. Jordan, LASL, Los Alamos, New Mexico
68 Arden E. Bicker, REECo, Mercury, Nevada
69 Clinton S. Maupin, REECo., Mercury, Nevada
70 Byron F. Murphey, Sandia Laboratories, Albuquerque, New Mexico
71 Melvin L. Merritt, Sandia Laboratories, Albuquerque, New Mexico
72 Richard S. Davidson, Battelle Memorial Institute, Columbus, Ohio
73 R. Glen Fuller, Battelle Memorial Institute, Las Vegas, Nevada
74 Steven V. Kaye, Oak Ridge National Lab., Oak Ridge, Tenn.
75 Robert H. Wilson, University of Rochester, New York
76 Leo K. Bustad, University of California, Davis, Calif.
77 Leonard A. Sagan, Palo Alto Medical Clinic, Palo Alto, Calif.
78 Vincent Schultz, Washington State University, Pullman, Washington
79 Arthur Wallace, University of California, Los Angeles, Calif.
80 Wesley E. Niles, University of Nevada, Las Vegas, Nevada
81 Robert C. Pendleton, University of Utah, Salt Lake City, Utah
82 William S. Twenhofel, U. S. Geological Survey, Denver, Colo.
83 Paul R. Fenske, Teledyne Isotopes, Palo Alto, Calif.
84 - 85 DTIE, USAEC, Oak Ridge, Tennessee(for public availability)
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