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

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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

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                                                                           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

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                           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%.

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                      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

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                         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

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                        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

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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.

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                           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

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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

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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.

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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.

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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

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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

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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

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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

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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

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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

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     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)

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