SWRHL-43r
1311 TRANSPORT THROUGH THE AIR-FORAGE-COW-MILK
SYSTEM USING AN AEROSOL MIST (PROJECT RAINOUT)
by
Richard L. Douglas, Stuart C. Black and Delbert S. Barth
Radiological Research
Southwestern Radiological Health Laboratory
ENVIRONMENTAL PROTECTION AGENCY
Las Vegas, Nevada 89114
Published June 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, subcontractors, 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; Michrofiche $.95
001
-------
SWRHL-43r
1311 TRANSPORT THROUGH THE AIR-FORAGE-COW-MILK
SYSTEM USING AN AEROSOL MIST (PROJECT RAINOUT)
by
Richard L. Douglas, Stuart C. Black and Delbert S. Barth**
Radiological Research
Southwestern Radiological Health Laboratory*
ENVIRONMENTAL PROTECTION AGENCY
Las Vegas, Nevada 89114
Published June 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
**Dr. Delbert S. Barth is presently Director, Bureau of Air Pollution
Sciences, EPA, Triangle Park, N. C. 27709
-------
ABSTRACT
Project Rainout was an experiment conducted to determine the
transfer of 131I from forage to dairy cow milk when the radio-
iodine was sprayed on the forage as an aqueous solution. Growing
alfalfa, cut as green chop, and spread hay were used as forage.
The peak activity in milk from cows consuming both types of
forage occurred about one day after the start of feeding. The
peak milk-to-peak forage ratio was 0. 013 for the cows fed hay
and 0. 041 for the cows fed green chop. The hay fed cows secreted
in milk an average of 4. 5% of the amount of 131I they ingested,
while the green chop fed cows secreted 6. 1%.
-------
TABLE OF CONTENTS
Page
ABSTRACT i
LIST OF TABLES iii
LIST OF FIGURES iv
INTRODUCTION 1
PROCEDURES 3
A. Experimental Design 3
B. Preparation, Deposition and Assessment of Hydrosol 7
C. Meteorological Instrumentation 10
D. Forage Collection and Animal Husbandry 11
E. Sampling Techniques I/
F. Sample Analysis 13
RESULTS AND DISCUSSION 15
A. Deposition and Assessment of Radioiodine Solution 15
B. Effective Half-life on Growing Alfalfa 23
C. 131j Activity in Dairy Cow Forage 23
D. 131I Activity in Milk 28
CONCLUSIONS 37
REFERENCES 38
DISTRIBUTION
-------
LIST OF TABLES
Table Page
1. Groups of cows and feeding schedule 6
2. System efficiency and minimum sensitivity for 131j 14
3. 131j deposition on planchets 16
4. Amount of precipitation at each sample position 18
5. Meteorological data during and after deposition
September 29, 1966 19
6. Air sampler data during and after deposition 21
7. Summary of the daily averages of 131j concentrations
(|j.Ci/kg) on forage 25
8. Mean concentrations of *31j in miik by groups (pCi/liter) 29
9. Effective half -lives of 131I in milk 33
10. Comparison of results from four studies 34
11. Percent of ^ I ingested which was secreted in milk 36
111
-------
LIST OF FIGURES
Figure
1. Layout of EPA Experimental Farm 4
2. Project Rainout study area 5
3. Aerosol spray procedure 8
4. Histogram of droplet size distribution 22
5. Mean concentrations of I in growing alfalfa 24
6. Mean values of ^ I in green chop 26
7. Mean values of ^ I in hay 2?
8. Mean concentrations of I in milk of Group I cows 31
i -31
9. Mean concentrations of -'I in milk of Group II cows 32
IV
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INTRODUCTION
The major mission of Radiological Research, a program of the
Southwestern Radiological Health Laboratory, Environmental Pro-
tection Agency, is to study the transfer of radioiodine from the
atmosphere to man via the route air-forage-cow-milk-man. Our
program is strongly field-oriented, and includes an experimental
farm at the Atomic Energy Commission's Nevada Test Site. This
farm consists of 17 acres of irrigated land, a 24-cow dairy herd,
and associated support facilities and equipment. Whenever
possible, we conduct our studies using contamination released
from Plowshare cratering experiments, reactor runs, and
inadvertent releases from underground weapons tests at the
NTS. Since these sources of radioactivity are relatively
limited, we supplement them by semicontrolled releases of radio-
active material at our farm. Two such studies (Projects
Hayseed and Alfalfa) have been conducted prior to the present
(7 8}
study. ' They both involved the release of a 3 I-tagged
diatomaceous earth aerosol over growing forage, which was sub-
sequently cut and fed to dairy cows. Although these studies
differed in aerosol particle size and the type of forage used, they
were both designed to study the deposition and uptake of a dry
particulate aerosol.
While deposition of radioiodine as a dry aerosol may be a major
fallout mechanism, other methods are certainly possible. One of
these is the removal of gaseous iodine from a cloud by the scrub-
bing action of rain, known as "rainout" or "washout". In such
-------
cases the iodine is presumably deposited on forage as an aqueous
solution. For this type of deposition, very little information is
available as to either the scrubbing mechanism or the behavior of
the activity after deposition on forage. In addition, the decon-
taminating effects of clean water added after deposition of the
activity, commonly referred to as washoff, are little understood.
This additional precipitation might result from continuing rainfall
after the cloud has passed, or from applying irrigation water
after the contaminating event.
The experiment described in this report was named Project
Rainout. It was designed to study the behavior of radioiodine
deposited on forage as a solution, both with and without the
application of additional water. For convenience, the I-tagged
solution is referred to as hydrosol, although it technically is a
liquid aerosol.
The specific objectives of Project Rainout were:
1. To determine the concentrations of 131I on spread
alfalfa hay and growing alfalfa as a result of applying
the 31I as an aqueous solution.
2. To determine the amounts of 131I in the milk of dairy
cows consuming the two types of contaminated forage.
3. To relate the concentration of 131I in forage to that
in milk.
4. To study the retention of 131I on growing alfalfa when
various amounts of additional water were applied after
the initial contamination.
-------
PROCEDURES
A. Experimental Design
The study area for Project Rainout (actual area of the experiment)
was a long narrow strip of growing alfalfa between two irrigation
laterals at our farm at the Nevada Test Site (Figure 1). The
design of the study area was based on feed requirements, forage
sampling, hydrosol deposition methods, and various operational
requirements (Figure 2). The resulting area was 235 meters
long by 5 meters wide having a total area of 1175 square meters.
The criteria for deposition of the 131 I solution were:
1. That the study area be uniformly contaminated in a
manner simulating a mist or light drizzle.
2. That precipitation levels be on the order of 0. 01 inch.
3. That droplet size be on the order of 70 to 500 microns.
4. That the contamination level be on the order of
105 pCi 131 I/kg of wet forage.
5. That the wind speed be in the range of 1-8 miles per
hour, with wind direction unimportant.
We felt that the mist or light drizzle criteria, with associated pre-
cipitation levels and droplet size, would be optimum for applying
contamination, since more, water or larger drops might tend to
flood the contamination off the alfalfa. Based on our previous
(7 8)
experiments * , the above cited forage contamination level
would give milk activity levels which could be easily measured.
The lactating dairy herd was divided into three groups of six cows
each as shown in Table 1. Cow assignments to each group were
-------
Barn, Hay Shed,
& Corrals
-X-
Gate
5 ,
r
J
Lateral Number
1
ORIGINAL UNCONTAMINATED GREEN CHOP AREA
T
Reservoir
PRJECT "RAINOUT" STUDY AREA
X
4
5
Foot Tower
SECONDARY UNCONTAMINATED GREEN CHOP AREA
8
X
^__-r_ —
Telemetry & Power
Poles & Cables
-X-
10
ii-
ia
14
16
-X-
j
Scale: 1" = 6O Meters
LAYOUT OF EPA EXPERIMENTAL FARM
FIGURE 1
4
-------
Lateral #3
Plot 1
Lateral #4
Plot 3
Plot 2
1»21 FTC IT*"
__2«J.£ Eao •'
Plot 4
Plot 5
>io
GREEN CHOP PLOTS
Hay
Lateral #5
Lateral #6
LEGEND
D 1-METER METEOROLOGY STAND
El 3-METER METEOROLOGY STAND
V AIR SAMPLER - DURING RELEASE
T AIR SAMPLER - AFTER RELEASE
• PLANCHET NUMBER (ODD NUMBERS
ALSO HAD PRECIPITATION MEASUREMENT)
Scale: 1" = 30 Meters
PROJECT RAINOUT STUDY AREA
FIGURE 2
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Table 1. Groups of cows and feeding schedule
Group
Cow No.
Type of Feed
Remarks
II
III
12, 13, 16,
18, 27, 28
19, 26, 43
45, 46, 47
2, 5, 11,
15, 21, 44
Contaminated hay (7.5 kg
morning and afternoon).
Contaminated alfalfa green
chop (12. 5 kg - 20 kg morn-
ing) and uncontaminated hay
(7.5 kg afternoon).
Uncontaminated green chop
(20 kg morning) and uncon-
taminated hay (7.5 kg after-
noon) .
Fed contaminated hay from
afternoon September 29 through
afternoon October 6.
Fed contaminated green chop from afternoon
September 29 through morning October 6,
then uncontaminated green chop
to the end of the study.
Control cows fed green chop from
Land #2 - September 29 through
October 3. From Land #8,
October 4 through October 6.
-------
based on a stratified selection made from a list arranged according
to the cows' milk production and the number of days in production.
This resulted in each group being as nearly the same as possible.
The cows in Group I were fed contaminated alfalfa hay each
morning and afternoon for eight days. Group II cows were fed
freshly chopped contaminated alfalfa forage (hereafter referred to'
as green chop) each morning and uncontaminated hay each afternoon
for the same period. Group III was the -control group, and these
cows were fed uncontaminated green chop in the morning and
uncontaminated hay in the afternoon.
B. Preparation, Deposition, and Assessment of Hydrosol
The hydrosol generation system consisted of a 29-foot, two-inch
channel beam suspended about one meter above the ground
between two pickup trucks. Twenty-two atomizing spray heads
were spaced along the beam at 15-inch intervals. The nozzles
of the spray heads pointed up and to the rear so that the axis of
o
the cone of spray was about 15 above horizontal. A 55-gallon
drum in each truck contained the radioiodine solution. Eleven
spray heads were fed from each drum. The drums were pres-
surized at a constant 40 psi from cylinders of dry nitrogen
carried in each truck. Alternate heads had orifices drilled to
1.59mm and 1. 19mm. These delivered, respectively, 0.34 and
0.26 gallons per minute (Figure 3).
Twenty-three mCi of 131 I were added to each of the drums, and
the drums filled with distilled water. Five grams of potassium
iodide carrier and enough 0. 10 N NaOH to maintain the solution
at H 8 was added to each drum. The contents of the drums were
P
thoroughly mixed and aliquots taken to quantitate the true l31 I
concentration.
-------
oo
. - - -
* >
^
1 '
v:
•**'
AEROSOL SPRAY PROCEDURE
FIGURE 3
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The tagged hydrosol was sprayed over the study area on Sep-
tember 29, 1966. The application was made in a single pass over
the area, starting at 1028 hours PDT and taking about 26 minutes.
At the end of the contamination run, clean drums were substituted for
the contaminated ones and the spray system was flushed before
starting the washoff spray. The washoff water was applied by
spraying clean tap water over three plots (Plots 1, 2, and 3,
Figure 2) after the contaminated spray pass. The vehicles were
driven in reverse over all three plots, then forward over 3 and 2,
then in reverse again over 2, thus giving three different levels of
precipitation on the plots. Plot 4 did not receive any additional
precipitation. On Plot 5, the irrigation system was used to add a
large amount of water for washoff. This water was added between
1530 hours, September 29, and 1100 hours, September 30.
The amount of precipitation was determined from the weight dif-
ferences of fifteen plastic petri dishes containing anhydrous
calcium sulfate. They were unsealed prior to the spray piiss and
resealed with a silicon lubricant as soon as possible after the pass.
Thirty 4-inch diameter stainless steel planchets were used to
quantitate the deposition of activity on the study area. They were
placed on wooden stakes 15" above the ground (the average height
of the alfalfa). Whatman 541 filters were placed in these plan-
chets following the release to absorb the solution and facilitate
drying prior to counting.
Gelman "Tempest" air samplers were operated on the anticipated
downwind side of the study area during the release (See Figure 2).
Following the release, sampler 4 was moved to the opposite side
of the area at approximately the same distance from the field as
sampler 3. Samplers 1 and 2 were moved to cleared areas near
-------
their original positions but within the study area in order to quan-
titate the resuspension of radioiodine. The sampling train con-
sisted of.a four-inch diameter Whatman 541 prefilter to collect
particulate activity and a MSA charcoal cartridge to collect
gaseous iodine.
Glass slides coated with a phenol red/n-Propanol film were mo-
mentarily exposed to the hydrosol by use of a special container.
These slides were subsequently used to determine the size and size
distribution of the droplets, uncorrected for any spread factor, by
measuring the diameter of the characteristic print remaining after
the liquid evaporated. A laboratory study was conducted following
the field exercise to determine the spread factors. For this study,
a vibrating reed was used to generate monodispersed droplets of
water. A stroboscope synchronized with the droplet frequency
effectively stopped the droplets in space so they could be photographed.
The droplets were allowed to impact on glass slides prepared with
the phenol red/n-Propanol film and the prints thus formed were
compared in size with the size of the droplet recorded on the photo-
graph. The procedure was repeated for various sized droplets and
a spread factor curve was developed. A more detailed description
of these methods is given in a report now in preparation.
C. Meteorological Instrumentation
Since weather conditions greatly influence the deposition and re-
tention of radioactive material, we routinely document the micro-
meteorology at the farm during and after a release. For Project
Rainout, meteorological instrumentation was installed at the study
area as shown in Figure 2. Wind speed and direction instruments,
with sensors at a height of one meter, were placed in two locations
within the study area. Another wind speed and direction instrument
10
-------
with sensors at three meters was placed at the midpoint and
immediately north of the grid. Instrumentation to measure tem-
perature, relative humidity, and evaporation was also placed at
this point.
The wind data were recorded on continuous-trace analog recorder
charts. Prior to and during the release the data were integrated
and tabulated at one-minute intervals. Following the release and
for the next seven days, the data were integrated and tabulated at
one-hour intervals.
D. Forage Collection and Animal Husbandry
The alfalfa hay to be contaminated was placed in the study area in
a stack 15 meters long by 5 meters -wide by 24 centimeters deep.
The hay was placed on a plastic sheet and covered with screen
wire. Following the release, the hay rations (7. 5 kg each) for
that day's feeding were weighed into polyethylene feed tubs. The
remainder of the hay was collected by weighing feeding rations
into plastic bags. The bags were sealed and stored near the
corral.
Fresh green chop was cut each day. Uncontaminated green chop
was cut first, then the contaminated green chop. After cutting the
contaminated green chop, the tractor, chopper, and wagon were
decontaminated with a high-pressure water spray. The daily ration
of contaminated green chop (12. 5 to 20 kg, depending on the amount
available) for each cow of Group II was weighed directly into a feed
tub from the wagon. The uncontaminated green chop for the con-
trol cows was fed free-choice from the feed bunk.
Unconsumed contaminated forage was weighed before disposal. This
amount was subtracted from the original ration in order to have an
11
-------
accurate record of each cow's consumption. The "uncontaminated"
green chop was cut from an area north of the study area for the
first five days (Figure 1). When this forage was found to be con-
taminated by resuspcnded 131I, the cutting area was moved south
of the study area.
The Group I and II cows were kept in individual pens at all times
except during milking. Each cow had an individual watering bowl,
feed tub, and milking bucket. At each milking, the control cows
were milked first, followed by the Group I cows, then the Group II
cows.
The cows of Groups I and II were removed from the individual pens
on October 10. They were, however, held as separate groups in
divided areas of the corral. Cows of Groups II and III were placed
together on October 12. On October 14, all cows of all groups
•were turned into a common corral.
Blood samples for blood chemistry and hematology were taken
from each cow before and after the experiment.
The details of animal care, feeding and milking procedures,
sampling techniques, record keeping, and equipment decontam-
ination are described in References 7 and 9.
E. Sampling Techniques
Hay and green chop samples were taken from each cow's feed tub.
The forage was spread evenly in the tub, and a handful was taken
from each surface corner and a handful from the bottom center.
The entire sample was sealed in a plastic bag.
Milk samples were collected by filling a one-gallon plastic con-
tainer (Cubitainer) directly from the milking bucket. After
®
filling, the outside of the Cubitainer was rinsed to remove any
(R) '
12
-------
spilled'milk. For composite milk samples, all milk from each
cow was poured into a common container and mixed thoroughly
and the sample taken from this composite.
Grain samples were collected daily from the bulk supply. Water
samples were collected daily by filling a Cubitainer from each
group's common source.
Five samples of growing alfalfa were collected from each of the
five treatment areas at each sampling time. Samples were taken
by placing a metal ring having an area of 0. 15 m2 in the center
of the designated area and cutting all plants within the ring two
inches above the ground level. The cut alfalfa was then sealed in
plastic bags.
F. Sample Analysis
The I content of the samples was determined by gamma spec-
troscopy. Our system consisted of a TMC Model 404C 400-channel
pulse height analyzer. Model 520 P punch control, Model 52Z
Resolver-Integrator, Model 500 printer, and a Tally Model 420
perforator. The detectors were two 4 - by 9-inch Nal(Tl) crystals
mounted facing each other with vertical spacing variable from
direct contact to 14-inch separation. Each crystal had a separate
high voltage supply and was viewed by four three-inch photomulti-
plier tubes. The crystal assembly was mounted in a steel shield
with six-inch walls. The inside dimensions of the shield were
39-by 42- by 42-inches, and it was lined with lead, cadmium, and
copper sheets.
Table 2 shows the types of sample containers used and the mini-
mum sensitivity for each type sample. The minimum sensitivity
was based on a 40-minute count and average sample size. The
13
-------
resolution of the system was 10. 2% based on the 137 Cs photopeak.
Table 2. System efficiency and minimum sensitivity for 131I
Sample type
Milk and water
Grain
Hay
Charcoal
(from air
sampler)
Green chop
Filter paper
Fallout planchet
Container
4-liter Cubi-
tainer
400-ml plastic
400-ml plastic
400-ml plastic
400-ml plastic
400-ml plastic
400-ml plastic
Efficiency
17. 3%
27.8%
28. 1%
27. 8%
34. 8%
48. 0%
48. 0%
Minimum
Sensitivity*
10+_5 pCi/1
80+10 pCi/kg
100+15 pCi/kg
30+5 pCi/sample
80+10 pCi/kg
15+5 pCi/sample
15+5 pCi/sample
*Based on a 40-minute count.
14
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RESULTS AND DISCUSSION
A. Deposition and Assessment of Radioiodine Solution
Of the 46 mCi of 131I in the drums, 44. 3 mCi were sprayed out.
At the end of the contamination run, four gallons of solution re-
mained in the drums. The fallout planchets showed an average
activity deposition of 24. 6 (o,Ci/m2 (Table 3). Using this figure,
we calculated that 28. 9 mCi, or 65. 2% of the 131I released, was
deposited on the study area. This contamination was deposited
with an average of 0. 007 inches of precipitation on the study area
(Table 4).
Two planchets had extreme deposition values which can be explained.
The high deposition of 55. 29 |J.Ci/m2 at No. 4 was due to a stop for
sprayer adjustments at this point. The low deposition of 3.82 [xCi/m
at No. 27 was probably due to sputtering of the spray caused by
movement of the solution in the nearly empty tanks. After deleting
these two values, the activity deposition varied by a factor of about
4 (10.58 to 45.64 u.Ci/m2). This variation is attributed to variable
wind speed and direction (Table 5), and uneven ground speed of the
trucks carrying the spraying system.
The levels of uncontaminated precipitation for the washoff study
were:
Plot 1 - 0.003" Plot 4 None
Plot 2-0. 041" Plot 5-8. 23"
Plot 3 - 0.032"
15
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Table 3. 131I deposition on planchets
Sample Position
1
2
3
4
5-
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Activity ((j-Ci/m2 )
32. 02
17-48
29. 11
55. 29
22.96
15. 24
24.76
24.76
38. 54
11. 69
22. 01
19. 10
19. 78
45. 64
22. 20
*
39.97
20. 22
27. 04
22. 37
28.93
30.76
25.96
:,'=
17.80
16. 32
3.82
25.96
16
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Table 3. I deposition on planchcts (Continued)
Sample Position Activity
29 10.58
30 18.81
Average = 24. 6 + 10.6
*Planchet dropped from stake
**Mean + one standard deviation
17
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Table 4. Amount of precipitation at each sample position
Sample Position Precipitation
(inches)
1 0.009
2 0.010
3 *
4 0. 007
5 0.012
6 0. 006
7 0. 005
8 0.008
9 0.015
10 0.006
11 0.008
12 0. 007
13 0.003
14 0.001
15 0.003
Average - 0. 007 +_ 0. 004 inches**
* Sample dropped from stake
-f-'f Mean + one standard deviation
The data from the four air samplers (Table 6) indicate some resus-
pension of activity after the deposition. The ratios of gaseous-to-
particulate activity generally increased during the afternoon and
correlate roughly with temperature rise. This is attributed to
volatilization and/or transpiration of the iodine from the plants.
Figure 4 is a histogram showing the distributioTT of droplet sizes,
uncorrected for the spread factor. The curve does not represent
a statistical best fit, but only implies an outline of the distribution.
A log-normal distribution of the droplet size has a geometric mean
of 283 (J. and a geometric standard deviation of 2. 05. When the
spread factor is applied to the size distribution, the geometric
mean is reduced to 139 JJL.
18
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Table 5. Meteorological data during and after deposition
September 29, 1966
Time
(PDT)
lozsW
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
10.50.
1051
1052
1053
East
1 Meter
Dir* Speed**
060
085
090
085
050
045
045
050
080
095
,075
060
065
070
085
080
080
075
055
055
055
065
060
045
040
045
07
07
05
06
08
07
05
04
06
08
08
07
06
04
05
05
05
06
06
07
08
07
06
06
06
06
West
1 Meter
Dir* Speed**
070
090
070
050
055
035
050
090
090
085
070
075
085
070
070
085
050
060
060
070
065
065
070
060
055
080
05
06
06
04
04
06
05
05
05
05
06
06
07
06
05
04
05
04
04
07
07
08
07
07
07
07
3 Meters
Dir* Speed**
030
040
060
090
030
050
045
050
030
035
075
085
080
055
055
060
070
070
060
075
055
045
040
045
060
060
09
09
09
07
07
09
09
07
07
07
09
11
1 1
10
09
07
07
07
06
09
09
08
12
11
10
10
Temperature Rel.Hum.
°F Percent
74
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
75
27
27
27
28
28
28
28
28
28
28
28
28
28
28
28
28
28
28
28
29
29
29
29
29
29
29
19
-------
Table 5. Meteorological
September 29,
data during and after deposition
1966 (Continued)
Time
(PDT)
1054(2)
1055
1056
1057
1058
1059
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
East
1 Meter
Dir* Speed**
040
065
075
085
085
090
090
090
180
200
160
190
185
190
255
315
315
325
335
05
07
06
06
07
08
05
05
06
06
04
05
06
05
02
02
03
03
03
West
1 Meter
Dir* Speed**
070
085
090
080
075
085
065
090
170
215
160
170
180
180
160
315
320
315
330
04
05
05
06
06
05
05
05
05
04
06
07
06
03
02
02
02
02
02
3 Meters
Dir* Speed**
040
035
055
035
035
060
065
090
180
215
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
10
08
09
08
10
08
08
07
08
08
06
07
10
08
04
02
04
05
05
Temperature Rel.Hum.
°F Percent
75
75
75
75
75
75
75
77
80
80
78
78
74
72
67
63
60
58
58
29
29
29
29
29
29
29
29
27
29
28
29
29
30
35
37
39
40
41
*Azimuth wind is blowing
**Miles per hour
(1) Start of Deposition
(2) End of Deposition
from
20
-------
Table 6. Air sampler data during and after deposition
Sampler Time Collected
1 1130<2)
1230
1340
1450
1550
1650
2 1130<2)
1230
1340
1450
1550
1650
3 1130(2)-
1230
1340
1450
1550
1650
4 1130<2)
1230
1340
1450
1550
1650
Total Activity^)
(pCi)
3.80xl04
1. 19xl05
1. 07x1 04
1.92xl04
5. 14xl03
4.44xl03
2. 61xl04
3.41xl04
. 3. 33xl03
8. OSxlO3
6.89xl03
7. 28xl02
3. 68xl03
3. 53xl02
4. 05x10*
8. 16X101
2. 13xl02
7.42X101
3. 67X101
1. 55xl04
1. I6xl04
5.85xl03
3. 31xl03
3. 12xl03
Char coal /Prefilter
Ratio
3. 2
17-3
13.4
13.7
10.8
6. 2
2.9
10.8
10.8
11.0
30. 6
17.3
2.6
4. 3
N.A.O)
N.A.(3)
0. 2
N.A.<3)
22. 0
5.2
7.7
6.7
5. 3
12.7
(1) Total of prefilter and charcoal cartridge activities.
(2) These samples collected during and immediately after deposition.
(3) Filter activity was non-detectable.
21
-------
63
163
263
363
463
SIZE (Microns)
563
663
763
863
HISTOGRAM OF DROPLET SIZE DISTRIBUTION
FIGURE 4
22
-------
B. Effective Half-life on Growing Alfalfa
The means of the 131I concentrations in the five samples collected
from each of the five plots at each sampling period are plotted in
Figure 5. The effective half-life, based on the best-fit regression
line from the mean values from all five plots, was 7. 0 + 0. 7 days. *
Statistical analysis indicates that the addition of various amounts of
water after contamination did not affect the decrease of activity
with time. The decrease of activity with time did not follow a
simple exponential function. Future investigations are planned
in an attempt to explain this.
C. 131 I Activity in Dairy Cow Forage
The daily averages of I concentrations in green chop and hay are
summarized in Table 7. The peak activity level of 2. 1 x 107 pCi/kg
in green chop was obtained on the day after the release while the
peak of 9. 8 x 106 pCi/kg in hay occurred on the afternoon of the
day of release. The daily averages of I in green chop and hay
are plotted in Figures 5 and 6 respectively. The effective half-life
in green chop was 4.5+^1.6 days, and in hay, 3. 6 +_ 0. 9 days.
These half-lives were calculated on the basis of a best fit regression
'line.
Since the hay was bagged and sealed shortly after contamination,
the short (3.6 days) half-life is puzzling. The rapid loss of 3 I
apparently was due to evaporation from the hay and the ultimate
escape of the 131I vapor through punctures in the bag or through
the plastic itself. The variation in effective half-life on gro-wing
alfalfa (7. 0 days) and green chop (4. 5 days) is probably due
to adsorption of activity on the chopping machinery.
In both types of forage, a rise in activity levels occurred toward
*Mean + one standard deviation.
Z3
-------
H
r
(D
UJ
IT
O
O)
jc
O
a
s io7
Teff = 7.O days ± O.7
• PLOT 1
A PLOT 2
» PLOT 3
- • PLOT 4
PLOT 5
10 12 14 16 18 20 22 24 26 28 30
DAYS AFTER DEPOSITION
MEAN CONCENTRATIONS OF 131I IN GROWING ALFALFA
FIGURE 5
-------
Table 7. Summary of the daily averages of 131I concentrations
(H-Ci/kg) on forage
Collection
Date
9/29
9/30
10/1
10/2
10/3
10/4
10/5
10/6
*Mean -
Time Green Chop
p.m. 19 12*
a. m. 21 +. 1
p. m.
a.m. 17+3
p. m.
a.m. 11 13
p. m.
a.m. 6.813.3
p.m.
a.m. 5. 2 1 2. 7
p. m.
a.m. 12 1 1
p. m.
a.m. 8.010.4
p. m.
f- one standard deviation.
Hay
9.8 1
5.8 1
4. 0 1
3.0 +_
3.4 1
1.6 1
1.71
2. 0 1
0.99 1
2. 0 1
2. 3 +
1.81
2.2 1
1.71
1.4 +
7. 1*
3. 7
2.3
2.9
3. 7
1.8
1. 1
1.8
0.85
1.6
2.6
1. 3
1.4
0.5
1. 1
25
-------
Teff = 4.5 days ± 1.6
456789
DAYS AFTER DEPOSITION
131
MEAN VALUES OF IJII IN GREEN CHOP
FIGURE 6
26
-------
3 —
2 —
Teff = 3.6 days ± O.9
I I t I I I
10
45678
DAYS AFTER DEPOSITION
11
12
131
MEAN VALUES OF 1JII IN HAY
FIGURE 7
27
-------
the end of the feeding period. This rise is especially sharp in the
green chop. As with the other erratic values discussed previously,
no logical explanation except uneven deposition over the study area
can be offered for this.
The intended uncontaminated green chop was found to have low level
contamination due to the resuspension of activity. Concentrations
of 4. 3 x 104 pCi/kg were detected on the day after the deposition.
After the eighth day, when the "uncontaminated" green chop was
being fed to the Group II cows, the 13 I concentration did not exceed
2. 7 x 103pCi/kg. Since this was three orders of magnitude below
the lowest value on contaminated green chop, it could not have
contributed more than 0. 1% to the cows' intake of 131I. Activity
levels slightly above the minimum detectable were found in some
grain and water samples, but these were also considered insignificant.
D. 131 I Activity in Milk
The mean values of I in the milk of Groups I and II are shown
in Table 8. The same data are presented graphically in Figures 8
and 9. Data for Group III cows are not included as they are con-
sidered controls and do not add significantly to the discussion.
The levels of 31I in the milk from both groups of cows rose
toward the end of the feeding period, giving a double peak effect
in the curves. These secondary peaks follow the peaks of the for-
age curves very closely, and the increased milk activities are
attributed largely to the combination of increased forage activity
concentrations and increased forage consumption. Toward the end
of the feeding period, the Group II rows were eating a larger
amount of more highly contaminated forage; apparently the green
chop was more palatable because of more succulent growth during
the latter stages of the study.
28
-------
Table 8. Mean concentrations of 131I
(pCi/liter)
in milk by groups
Date
9/29
9/30
10/1 .
10/2
10/3
10/4
10/5
10/6
10/7
10/8
10/9
10/10
Time
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
a.
P-
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
m.
Group
1.
9.
1.
1.
1.
7-
6.
5.
6.
5.
6.
6.
7-
8.
8.
8.
6.
2.
1.
9.
7.
4.
4.
6xl04
5xl04
3xl05
2xl05
IxlO5
2xl04
5xl04
6xl04
OxlO4
5xl04
4xl04
8xl04
6xl04
5xl04
8x1 04
IxlO4
7x1 O4
7x1 04
8xl04
2xl03
2xl03
2xl03
2xl03
I (Hay)
+
+
+
+
+
+
+
+
+
+
+
+
•f
+
+
+
+
+
+
+
+
+
+
I-
5.
0.
0.
0.
3.
1-
1.
1.
1.
1.
2.
2.
2.
3.
3.
1.
0.
0.
1.
2-
1.
1.
6*
6
7
6
6
0
8
1
3
4
9
6
5
8
7
1
8
6
3
9
0
4
4
Group II (Green
1.
4.
8.
5.
8.
5.
7.
5.
6.
4.
6.
3.
7.
4.
7.
5.
4.
2.
1.
8.
6.
5.
3.
6xl05
5xl05
6xl05
3xl05
IxlO5
9xl05
7xl05
3xl05
IxlO5
7xl05
IxlO5
7xlOs
5xlOs
7xl05
8xl05
6xl05
2xl05
IxlO5
7xl05
5xl04
8xl04
4xl04
3xl04
+ 0.
+ 1.
+ 1.
+ 1.
+ 1.
+ 1.
+ 1.
+ 2.
+ 1.
+ 1.
+ 2.
+ 1.
+ 1.
+ 1.
+ 2.
+ 1.
+ 1.
+ 0.
+ 0.
+ 3.
+ 3.
+ 2.
+ 1.
Chop)
5=:=
1
8
2
5
1
5
1
8
7
3
3
9
1
0
2
3
7
8
7
4
0
7
29
-------
Table 8. Mean concentrations of 131i in milk by groups
(pCi/litcr) (Continued)
Date Time
10/11 a.m.
p. m.
10/12 a.m.
p. m.
10/13 a.m.
p. m.
10/14 a.m.
10/15 a.m.
10/16 a.m.
10/17 a.m.
10/18 a.m.
10/19 a.m.
10/20 a.m.
10/21 a.m.
10/22 a.m.
10/24 a.m.
10/26 a.m.
10/28 a.m.
2.
1.
1.
7.
5.
5.
5.
3.
4.
2.
2.
2.
4.
1.
1.
2.
1.
1.
Group I (Hay)
OxlO3 +0.7
6xl03 + 0. 5
OxlO3 +0.4
8xl02 **
6xl02
8xl02
IxlO2
IxlO2
SxlO2
9xl02
4xl02
SxlO2
2X101
7xl02
4xl02
SxlO1
4xl02
6xl02
Group II (Green Chop)
l.SxlO4
1.4xl04
7. IxlO3
7- OxlO3
3. 6xl03
3. IxlO3
2. 6xl03
2.2xl03
1. 6xl03
1. 3xl03
1. 2xl03
l.OxlO3
6. 6xl02
6. 5xl02
6.7xl02
4. 3xl02
4. 9xl02
3.9xl02
+ 0.8
+ 0.8
+ 3.9
+ 3. 2
+ 1.7
+ 1.2
+ 0.9
+ 0. 3
+ 0.4
+ 0.4
+ 0.4
+ 0.6
+ 3. 1
+ 1.6
+ 1.8
+ 3.0
+ 1.9
+ 1.0
•'-'Mean + one standard deviation reported.
':*Milk from all cows in this group was composited from this date on.
30
-------
10*
1 r
i 1 1 r
• Last Feeding of Contaminated Hay
1 1—=1
-i Teff = 2.5 days ± O.4
UL
UJ
10
O
a
Teff = O.94 days ± O.O4
10
Teff = 5.6 days ± 2.4
10
1 I I I L
l I I L
J L
J I I I L
02468
10 12 14 16 18 20
DAYS AFTER DEPOSITION
22 24 26 28 30
MEAN CONCENTRATIONS OF 131I IN MILK OF GROUP I COWS
FIGURE 8
-------
io
10
Contaminated Green Chop
i—r
i—i—i 1—i—r
i
\
Teff = O.86 days ± O.O2
n 1 1 1 1 r
12 14 16 18 20
DAYS AFTER DEPOSITION
22 24 26 28 30
MEAN CONCENTRATIONS OF 131I IN MILK OF GROUP II COWS
FIGURE 9
-------
The nature of the feed data precludes a calculation of a meaningful
effective half-life in the milk during the feeding period. Therefore,
a reasonable approach is to calculate the effective
half-lives from the peak milk to the valley of the double peak.
Effective half-lives were also calculated for two distinct periods
after the end of feeding. These half-lives are shown in Table 9.
Table 9. Effective half-lives of 131I in milk
Days after start Group I Cows Group II Cows
of feeding (Hay) (Green chop)
2nd through 6th 2. 5 +_ 0. 4 days 7. 9 +_ 4. 3 days
10th through 15th 0.94 + 0.04 0. 86 +_ 0. 02
16th through 28th 5.6 + 2.4 5. 1 +_ 0. 5
In Table 10 the results of this study are compared with the results
from three of our previous studies. Projects Hayseed and
(8)
Alfalfa were controlled releases of 131I-tagged dry aerosols
over grass or alfalfa-grass forage at our farm. We also con-
ducted a field study at two commercial dairies following the Pike
Event , an underground nuclear test which produced an inad-
vertent release of fission products to the atmosphere. During
feeding, the'effective half-life in milk from hay fed cows was
close to that found on Hayseed, but considerably less than those
from Alfalfa and Pike. For green chop fed cows, the effective
half-life was two to three times that found in previous studies.
After feeding of contaminated forage stopped, the half-lives were
in reasonable agreement with those reported in the literature.
In both groups, the peak milk value occurred on the afternoon of
the second day of feeding or about 24 hours after ingestion of the
first contaminated feed. This is in reasonable agreement with
33
-------
Table 10. Comparison of results from four studies
Study Type of Type of
Contamination Green
Chop
Pike Fission Alfalfa
March Products
1964
Hayseed 13 ^-Tagged Sudan
October Aerosol Grass
1965 (23 uCMD)
Alfalfa 131I-Tagged Alfalfa-
June Aerosol Oats
1966 (2 (J.CMD)
Rainout 131 1 Solution Alfalfa
October
1966
Forage
Peak Average
Concentration (pCi/kg)
Green Chop Hay
4.7xl03 1.3xl03
2.7xl06 4. IxlO5
3.4xl06 5.6xl05
2. IxlO7 9. 8xl06
Milk
Peak Average ^eff During Time to Peak
Concentration (pCi/liter) Feeding (Days) (Days)
Green Chop Hay Green Chop Hay Green Chop Hay
3.8xl02 7-OxlO1 3.8 5.9 4 3
2.2x10" l.lxlO4 3.0 2.7 2 1
l.OxlO5 3.9xl04 2.5 8.2 1.5 1
8.6xl05 1.3xl05 7.9 2.5 1 1
Peak Milk (pCi/1)
Peak Forage(pCi/kg)
Green Chop Hay
0.080 0.054
0.008 0.027
0.029 0.069
0.041 0.013
-------
our other experiments.
The ratios of peak average milk activity to peak average forage
activity were 0. 013 for the cows fed hay and 0. 041 for the cows fed
green chop. This indicates that for this type of contamination and
forage, radioiodine is more biologically available from alfalfa
green chop than it is from hay. The same trend was observed with
actual fallout from Pike, but the reverse case was true on Hayseed
and Alfalfa, where the milk/forage ratios were higher for the hay
cows.
Table 11 shows the percent of the total 131I ingested which was
secreted in milk. The cows which ate hay secreted 4. 5 + 1. 5%
of the total 31I ingested, while those which ate green chop
secreted 6. 1 + 1.4%. While this would also indicate a greater
biological availability of iodine on green chop, there is no signi-
ficant difference between the two percentages.
The ratio of maximum milk concentration to minimum milk concen-
tration at each milking was calculated. The mean of these maximum/
minimum ratios was 2. 98 + 2. 24 for Group I and 2. 86 jf 0. 96 for
Group II. This is a measure of the variability between cows as a
herd and as groups.
35
-------
Table 11. Percent of 3 11 ingested which was secreted in milk
Co-w
Group No.
II 19
(Green 26
Chop) 43
45
46
47
Total [o.Ci Total p.Ci Percent Mean -f One
Ingested Secreted Secreted Standard Deviation
I
(Hay)
12
13
16
18
27
28
292.5
302. 3
251.0
289. 1
376.7
322.0
19. 1
14.4
13.7
7. 3
16. 0
10. 6
6. 5
4.8
5. 5
2.5
4.2
3. 3
4.5 + 1.5%
1320. 5
1011.8
1474.6
1648.2
1561.8
1472.8
63. 5
72.7
88. 6
71. 5
126. 2
96. 0
4. 8
7- 1
6.0
4. 3
8. 1
6.5
6.1 + 1.4%
36
-------
CONCLUSIONS
When radioiodine is deposited on forage (growing alfalfa and hay)
in an aqueous solution under the conditions of this experiment, the
following conclusions concerning the transfer of the radioiodine
to cow's milk may be drawn:
J_. I on fresh green chop appeared to be more biologically
available than it was on hay.
Zj. Following ingestion of the contaminated forage, the peak
activity concentration in milk (pCi/liter) occurred in about
one day. This concentration was one to two orders of magni-
tude lower than the peak concentration in the forage (pCi/kg).
3. After ingestion of the contaminated forage was stopped,
the effective half-life of 131I in milk was about one day for
the first six days, then about five days until negligible con-
centrations were reached.
4. Dairy cows eating contaminated green chop secreted 6. 1%
of the ingested 131I in their milk, while those eating contami-
nated hay secreted 4. 5%.
5. Although it appeared that there was no washoff effect, the
statistical design of the washoff experiment was not sufficient
to allow any definite statements about the effect of additional
precipitation. However, the effective half-life of I on
growing alfalfa was about seven days.
37
-------
REFERENCES
1. D. S. Earth and J. G. Veater, Dairy farm radioiodine study
following the Pike Event, Report T1D-21764, November 1964.
2. Radioiodine study in conjunction with Project Sulky, Southwestern
Radiological Health Laboratory Report SWRHL-29r, May 1966.
3. S. C. Black, D. S. Earth, R. E. Engel and K. H. Falter, Radio-
iodine studies following the transient nuclear test (TNT) of a
KIWI reactor, Southwestern Radiological Health Laboratory
Report SWRHL-26r, May 1969.
4. S. C. Black, R. E. Engel, V. W. Kandecker and D. S. Earth,
Radioiodine studies in dairy cows following Project Palanquin,
Southwestern Radiological Health Laboratory Report PNE-914F,
in press.
5. D. S. Earth, R. E. Engel, S. C. Black and W. Shimoda, Dairy
farm studies following the Pin Stripe event of April 25, 1966,
Southwestern Radiological Health Laboratory Report SWRHL-41r,
July 1969.
6. R. L. Douglas, Status of the Nevada Test Site experimental farm,
Southwestern Radiological Health Laboratory Report SWRHL-36r,
January 1967.
7. S. C. Black, D. S. BarthandR. E. Engel, Iodine-131 dairy cow
uptake studies using a synthetic dry aerosol (Project Hayseed),
Southwestern Radiological Health Laboratory Report SWRHL-28r,
in press.
8. R. E. Stanley, S. C. Black and D. S. Earth, Iodine-131 dairy
cow studies using a dry aerosol (Project Alfalfa), Southwestern
Radiological Health Laboratory Report SWR1IL-4 2r, August 1969.
9. D. D. Smith and R. E. Engel, Progress report for the Eioenviron
mental Research Part I; Experimental dairy herd, Southwestern
Radiological Health Laboratory Report SWRHL-55r, March 1969.
38
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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, Maryland
51 - 52 Charles L. Weaver, Act.Dir., Div. of Surveillance & Inspection,
Radiation Office, EPA, Rockville, Maryland
-------
Distribution (continued)
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)
------- |