[ASSESSMENT OF HUMAN EXPOSURE TO RADIONUCLIDES …stream. Radionuclides in dewatering effluent from...
Transcript of [ASSESSMENT OF HUMAN EXPOSURE TO RADIONUCLIDES …stream. Radionuclides in dewatering effluent from...
THE ASSESSMENT OF HUMAN EXPOSURE TO RADIOKUCLIDSS
FROM A LRANIUM MILL TAILINGS RELEASE .--.r-T-^lAND MINE DEWATERING EFFLUENT lfc ' ' f'wh''-•
A. JAMES RUTTENBER, JR. ^ AUG0.2?center for Environmental Health -•—""" ^-^~-~^
Centers for Disease Control, Public Health Service RADIATION PROTECTION BUREU^S* Department of Health and Human Service s > \r,
Atlanta, GA J30333
KATHLEEN KREISSCenter for Environmental Health
Centers for Disease Control, Public Health Service,U.S. Department of Health and Human Services,
Atlanta, GA 30333
0
C
RICHARD L. DOUGLAS
Envirorasental Protection Agency, Las Vegas, W 89114
' ^'THOMAS E. BUHLNew Mexico Health and Environment Department
Santa Fe, NM 87503
JERE HILLARDNew Mexico Health and Environment Department,
Santa Fe, NM 87503
Abstract - This study provides an assessment of hmnan exposure toradiation from a river system contaminated by radionuclxdes releasedthrough a dam break at a uranium mill tailings pond and by thecontinuous discharge of dewatering effluent from two uraniun -ulines.
.Data are presented from the in vivo analysis of radionuclides la sixKavajo Indians who lived near the river. Dose estimates are rcade fort ifi-isaJJi-pathwaJ-s—o .s-.E^di -i :of.-d&se^-i^;'from the ingestion of livestock suggest that'the najor contribution tohuman exposure is from mine dewatering effluent that has beencontinuously released into the river system for nany years- Although£he estimated exposures do not exceed existing State or Federalregulations, their magnitude justifies further surveillance ofradionuclides in animals and in the natural environment and furtherefforts to reduce radiation exposure to. humans and aninals" •
-a's 'ijPii.ifttidi---- i- .•if-WH^ fr-^t
000755
IKIKODUCT10N
The clarification of radiation exposure to humans following the
accidental release of radionuclides into the environment is a. natter of
great concern to the nuclear industry, the public health sector, and the
general public alike. This paper describes initial efforts to estimate
public radiation exposure after a dam break at a uranium mill tailings
pond*. Investigations of accidents su>:h as this also provide insight
into the effects of chronic exposure to industry-related releases of
radionuclides-
Early on the morning of July 16, 1979, a breach occurred in the
earthen retainii^g dam of a tailings pond of the United Nuclear
Corporation^ (UNC's) Church Rock uranium mill. The water
(approximately 94 million gallons of acidified effluent) and tailings
slurry (approximately 1,100 tons) spilled r-hrough the damaged portion of
the retaining wall into the pipeline arroyo that is a tributary to the
Rio Puerco River systea- Fhe Rio Puerco runs through Galiup, New Mexico
(population 18,000), and eventually crosses the New Mexico-Arizona
border (Ftg. 1). On its way to L "lup, the Rip PuercQ Apd it@
tributaries pass through, la n4 with ^ ci^ckerboard pattern of ownership^
with portions owned or leased by the Navajo, private individuals^ the
Bureau of Land Management» and the state.
In tenng of tailings liquid volume, the UNC spill ranks as one of
-l ^fc^-la'rgesY-^n^-to^i^ in rhe--"'-it • i- *-i—.
t. m.
slurry appears to be close to the median for accidents of this kind,
however. The circumstances that resulted in the dam break have been
reported elsexmere (Ru81), and the concentrations of radionuclides
000756
SCALE
•:0<- i :i i
ynyawuMi M»i I—IBM im •oTynn ,,^ •-,._.--^••i.^ ;ifr>.v;"^"V. . . t..'. l.-t^,*4^lT,4-•-,^. ».', ,
000757
released into the environment have been measured by the New Mexico
Environmental Improvement Division (KHB1D) (report in preparation).
The UNC Church Rock mine» adjacent to the UNC mill, has, since
1968, continuously released dewatering effluent into the pipeline
arroyo at a rate of 1,400 gal per min. Before 1975 this effluent was
not treated; after 1975 it received precipitation treatment for
7*?A
removal of Ra* Kadicnuclides are also released into the river
system through the dewatering of the Kerr-^icGee uranium mine located 1
©ile north of the UNC mill (Fig< 1), During usual mining operations,
approximately 3,600 gal of effluent per min are released into the
pipeline arroyo and then into the Rio Puerco- The continuous release
of Kerr-McGee dewatering effluent began in January 1972. Th^ efflue.at
from both mines has transformed the downstream portion of the Rio
Puerco from a sporadically dry riverbed to a continuously flowing
stream. Radionuclides in dewatering effluent from both mines have
contributed to the current levels of background radiation along the
*? 7^river system* In 1974 the Kerr-McGee dine began Ra precipitation
treatment of its dewatering releases, but data obtained by NKEID
indicate that treatment has been incomplete on many occasions.
An initial review of environmental data collected after the mill
tailings spill suggested potential human exposure from inhalation of
re ^usp ended <3ry^ta'irings"and" 'i'ngestion""o'f 'dome'stic' aMniais^ that?"~~:''"r?""'
watered froa the Rio Puerco. Other potential exposure routes were
considered but ruled out because no residents of the Church Kock area
(between the mill and Galiup) used Rio Puerco water for personal
000758
consinaption, and only a few szaall gardens were adjacent to the river'
Contamination of regional groundwater was also evaluated but
considered unimportant as test wells showed no chronically elevated
radionuclide concentrations in groundwater after the spill. During
the initial evaluation of environmental data it became apparent that
radionuclide concentrations in the river water were also influenced by
the de-watering effluent from the UNC and Kerr-^lcGee uranium i2ines-
Because prespill background levels of certain radiocuclides had not
heen adequately measured^ the clarification of relative magnitudes of
radionuclide contribution was impossible. The data in this report,
therefore, reflect the combined ef fects of the mill tailings accident
and the chronic dewatering releases*
. -,„.; ., . . ,1 ,-..-, ™ - 1 ,1 . 1 „. ». «»..li.J,.-ffiJfeS
METHODS ^ ]
Atniospheri c Monitor! ng
Airborne particulates were collected for radionuclide analysis
with a high--volume air sampler located on a bs-rk of the Rio Puerco
near Galiup, New Mexico (Pig. 2). The sampler operated continuously
between August 22 and September 28, 1979, and between Koveaber 21^
1979, and January A; 1980. The filters (99.9% efficient: at 0.^) were
analysed for U-nat, ^Th. ^R^ ^°Pb, and ^Po. One 7-hour
sample was collected with a cascade iapacto^ to measure the particle
v size distribu'tion.of 'tbI^^ixbox.a^'pArtacul^ taken"" "^"" ' rr:' ,
downwiiBd from where a UNC cleanup crew was working, in the Pinedale :1,•'.!• • '•
Bridge area near station 6 (Fig. 2), and represents worat.^ase ,,
conditions for occupational exposure. . ,.. -" „ . ' " ; . , - - , " -a --i -^ - • • ' • ^--"t-- • • • ' ,. i, * . • • , ; - - ' . • , - . • - « • . - . . . ._ • .. „ --.a
,^^,,,,..^,.^..^——— • • .-^^••'•-:•t^W^ .^-v^^^^-.^^^•Ll••'^•t"^^•y•- "" •""-'^
^m^^mr-________m———^———*——^^^.^^^^————'^^^^j^^^^^^-^^^000759
»tl
J. ,.. —,. ,,„.., ,.,««„, i.. , .-.,,-r.
6 t't I-d-n—«-r^--^p^..iiL..L>* • l i '
F • - - • " • • • l , • ^ ] I - l ^ — -
.- ! ) •
S ~<v - - ^ -, ,-, . .. L . .,-. ,^^^-,JJ,. ,. .^-^.
- .• - I ti , :•, - 1
•l^^y|rT«•y^rlr••^—ll^^^••^l••"l«rlll»^" »^-<" i.-- . T ..ui»r p ' ..-r*r.-.i-'»-'»-1 • ^ •• ".. . <• . »• • V
^ .MII.- W. ^,.(U»»1
'• • *• • ^k
000760
In VI vo Analysis
In vivo monitoring was ubed as a screening technique for evaluating
acute radiation exposure from the tailings spill* Aerial photographs
and inforaation from representatives of the Church Rock community were
used to select individuals who were most likely to have been exposed to
the tailings contamination and who would consent to in vivo monitoring-
Six persons (five children and one adult) underwent
whole-body counting for 30 min each at the Los Alaiaos Scientific
Laboratory (LASL) on August 23, 1979< The locations of their
residences are shown in Fig. 2.
Tlie gaoma spectroscopy counting system used for whole-body
counting was housed in a low-background chamber and included the
following arrangement of equipment. Twin Phoswich detectors .(each
composed of a sandwich of sodium and potassium iodide phosphors) were
placed over the chest for monitoring low-energy photon emitters such
40 137as K, Cs, uranium^ thorium, and their daughters. A hyper-pure
germanium (HpGe) detector was placed over the liver region for
iaonitoring low-energy photon emitters of the uraniinn decay series- A
large-volusae lithium drifted, germanium (Ge(Li)] detector was placed
under the subject to monitor the whole-body radiation from energetic
f f\ "I 0 *T
photon emitters of the uranium decay series,, K, and Cs«
A spot urine sample was collected from each subject on the day of
- » ^-. ,*, ^ „ J. ^ • - • . « - >* , •^-^._^^^^s » _ - ^ ^_ ^ -— " * ^ _ J^^.^- _ '~^~'." * . t -—^J' _ . ^"^ '- •'JJ^Egrty^ET -?" '—
Whole-body counting, and a 2^-hour s^%ple on the; nasU,-day.'" LASL•r 1_ -«;J ^_- -r ——— ——T»—————— '"''.' 'tS*. . .^<;
analyzed thesa ^^apies for gross alpha, beta^ and ganaa concentrations,
as well as for concentrations of specific radionuclides of the 2 U
decay series. Gross gamma activity was measured with a 4-in* x 4-in-
^ S"^- •,f
000761
Nal detector over an energy range of 0-2.0 MeV. For each subject, the
entire spot urine sample was counted» and a 400-cc aliquot of the
2^-hr collection was assayed- Each sample was counted for 2»000 s.
Gross beta activity was measured with 2"pi windowless gas flow
proportional counter, using planchets that were plated with 0.5^cc
aliquots of the sample. An energy range of 0-167-1-7 MeV was examined
for a counting time of 60 min, with a counting efficiency of 61^-73JS.
Gross alpha activity was measured by packaging the same planchet
samples with a ZuS-coated mylar film and counting with a scintillation
counter at an efficiency of 49.4 4- 1.1^ for l»000riin.
Uranium was analyzed by neutron activation and delayed neutron
235counting of U in 25-cc aliquots of each urine sanple at the LASL
Omega We^t Reactor Facility* Thorium was analyzed colorimetri.cally
and radioQetrically by using 200~cil aliquots of the 24-hr urine
samples. The colorimetric method employed arsenazo-IIl dye as a
chromagen for thorium- The radiometric analysis involved precipita-
tion of metals from aliquots (125-500 cc) of urine from four
individuals by the oxalate method^ ion exchange, and subsequent
electroplating onto stainless steel planchets. The samples from
Church Rock subjects were compared with control samples composed of
pooled urine from LASL employees not exposed to radionuclides and withf) in ?i'?
a solution spiked with Th and decay products of the Th
series. The planchets were counted i.n the alpha scintillation system
described previously* After alpha scintillation analyst^ planchess
were counted for 1 ,212 min in an alpha spectrometer gated for 2.°-7*3
MeV to detect the ^Th and ^Th decay series (excluding 21 Po) •
000762
* ) ' ) fr,The 24-hr urine samples vsre also analyzed for P^a by using a
de-emanation technique. Aliquofcs of 200 cc •were allowed to sit for 32f) ' ) A r ) ' ) r) 17'7'7
days to permit equilibrium between Ra and Rn. The R.n was
then isolated and counted for 900 min-
'Estimation of Radionuclide Concentrations in Animals
Buman internal exposure to radi.onucl.tdes could also result from
eating local livestock that watered in the F4q Puerco- Sheep^ .cattle,
and goats that grazed along the Rio Puerco and its tributaries were the
domestic animals most likely to have been exposed- Several ^avajo herds
have depended upon this river systen as their sole source of drinking
water, even since the dam break*
Two cows, four sheep, and two goats were purchased from the Church
Rock area (Fig. 2) for radionuclide analysis. As controls^ one cow^_'_ m^,^-^^-<,^rfiina',s"^ -s^c^ i ii-iai 33^^^^^-iyi3^"'-i&iE^^^*fi "^^^"' ^ ^-'- •' ^-'^' •- ~ i -;-^ — '
^and.tvo sheep were purchased outside the Church Rock area. Most
Church Rock animals received both acute exposure froa the spill and
chronic exposure from the mine devatering effluent. Six of these
animals and the three control animals vere autopsied^ and tissue
samples of muscle, liver, kidney, and bone were removed from each
animal. Ths samples were analyzed for concentrations of ^U^
235y 234 232.,, 230_ 226. 210-, , 210,-u* "> Th^ Th, Ka, Pb, and Po.
jteth^d^£orpatectingSadionllclides in Aniaal Sassples
The methodology for measuring radionuclid-e concentrations -was an
^•",Jy^--^^,^«-t.^^^^.^^J^^_^^\,^^^—r"''-:-.' '"*^ ••""•.'" r^"".'.-1^:"^.- ^"-'rrr-^.-'J " " w -adaptation Q,£..a. procedure developed a£ EPA"~Li^:V%ga^tJoT^^l^ir^^^
238naturally occurring U series on polystyrene air filters. In this
procedure samples were first wet-ashed vith a combination of nitric
acid, sulfuric acid, and hydrogen peroxide to prevent volatilization
000763
of polonium and lead. The bone samples were decomposed with only
nitric acid and hydrogen peroxide to avoid the precipitation of large
quantities of calcium sulfate. Samples of bone were also boiled in
1.5 1- of water for 8 hr to simulate leaching that might take place
when bones are included in soup. After the organic isaterial was
destroyed, samples were treated with hydrofluoric acid to dissolve and
c "
volatilize silicates, and then treated with hydrochloric acid* ^-- -^
Samples were split into two equal fractions for sequential uraniun,
/—.polonium, and thorium separation by anion exchange and for sequential
radium and iron separation by precipitation techniques. Before
219 ?OR ;
decomposition^ all samples were spiked with U, . Po, and ,. . .\...^3Sn • y / ---_ -r:,-i
Th tracers and a stable lead carrier to determine the chemical
recoveries of these elements in the separation procedures.
In the anion exchange separation each sample was diluted with 9 H
HC1 and passed through an anion exchange column, which removed uraniun
and polonium* Absorbed iron was eluted with Hl and uranium and
polonium were sequentially eluted with dilute HC1 and concentrated
ENO^r The original eluate (containing thorium) was diluted with 7 M
HNO^ and passed through the column again to remove the thoriwa. The
.AA^^-A, •I. <&h<
^ ' . ..* . . , -
thorlura was then eluted with 9 H HC1< The uranium and thorium
fractions were converted to sulfates and electroplated on stainless
steel discs" The polonium fraction was converted to its chloride salt
^»^~ —— "i •*- '—---"•• "r '- '' "* .r-.;— -i~(,——Ar »^ £.-;—»——, •-fc—.—u:([ •a_ .i;_B , —, —«_ ?._, * «- _ ,„."_ ____ . • -• - - - — _," "L. ; „
'and spontaneously plated on--a nickel crsc. K^h o.F'fche'th'&ee'-tJrscs-^-
3-tA 9^S '^'^fiwas counted on an alpha spectrometer to measure u» u, U,
230», 232.,, 210-, , ,, 232,, , 208.,Th, Th, Po, and the U and Po tracers* Thorium
o t/recovary ^as determined by beta counting for Ih-
- • ' - - . . .•,,;•-,•---- .^^^i^^?^^-'-?-;'"-^—'^-—^"11-^11''' • •-•--•SV——— • - - - . ' — ' -' '" • ' : •".;?.. . . . . . . . . .
000764
Table 1. Detection Limits for RadionuclideAnalysis of Animal Samples^
Church Rock, New Mexico, 1979
Per SampleRacLLonuclide (pCi)
100 g Tissue 5 g Bone(pCi/kg) (pCi/kg)
U, Ih
Po
Pb
Ra
0.03
0.3
1
0.3
0.3
3
10
3
6
60
200
60
:-"&
• r^,. wwv f—'^s-•••-^
000765
210'Radiuni-226 apd Pb were separated by precipitating Ba(P^a)SO/
in the presence of BC1 and then precipitating PbSO/ after the chloride
99ftanion was removed by evaporation. The concentration of Ra was
detem.ined by the classical emanation technique. Lead-210 was measured
210by allowing its Fo daughter to ingrow for approximately 3 months^
spontaneously plating the polonium on a nickel disc» and analyzing the
210disc by alpha spectrometry. For Pb analysis, the lead recovery was
determined by atomic absorption analysis of the added lead carrier, and
the recovery of the ingrown polonium was determined by measuring a
I | m . / 1 1 1208 210.second Po spike added at the time the Pb was isolated.
Betection limits for a typical analysis can be estimated iron the
reagent blank analyses performed during this study. These limits are
expressed per sample, per 100 g tissue^ and per 5 g bone (Table 1 ) "
RESULTS
At&ospheric Monitoring
The high-volume composite air sample data and the dose conversion
factors of Dunning et al. (Bu79) were used to calculate inhalation
doses to those huaan tissues receiving the highest doses- To provide
the most conservative es-timates of inhalation doses for the residents
of Galiup, all material deposited on air sampler filters was
considered respirable- This assumption is supported by data frcn the•;—" —»— -——^i ._- . i' f - t — ' - _ _ _ • - ; — - —- - -«— - . - . . . - - . - - . * • -•
single cascade itspactor sample^ which showed the diameters of all
collec-ted parfciculates to be between 0.3U and 3.3P""~si2;es considered
3-xespirable by buiaans^ Inhalation rate was assumed to be 15 m /day,
and duration of inhalation^ 1 year; quality factors wve selected to
000766
give the most conservative dose, estimates. Fifty-year dose
commitments from annual exposure (in arem for clearance class W) of
1 7 » 1, 15, and A were computed for bone, spleen, endosteua, and .lungs,
230respectively. Th contributed the greatest single radionuclide
dose to the endosteum» ,--JEh, the greatest dose to bone, and Po
to spleen and lungs. The use of clearance class D for U"nat and
210 230<Po, and class Y for U"nat and ^"Th did not appreciably alter
the calculated doses- It should be noted that the atmospheric
concentrations used in the calculation of doses for Galiup residents
reflect a combination of contributions from background, nine
dewatering effluent,'and the aill tailings spill. The siuilarity of
these concentrations to background concentrations measured in other
mining and milling areas suggests that the spill material did not
contribute significantly to the Galiup radionuclide concentrations*
Human inhalation doses based on cascade impactor data were
calculated in a similar manner., but for an occupational exposure
period of 40 hrs per week. Pifty-year dose cocuQitments (in mrem for
class W) of 50, 1, 204, and 5 were calculated for bone, spleen,
endosteum, and luags, respectively- It should be emphasized that the
-3
cascade impactor data reflect high dust loading (79^ pg/m ) and nay. ., . . • . -- .-'••- ;.' 'i - w .•• . ; • - . , - ' ' " ' '• "S ' • ' f '?. "• •"'" • • • ' " '
result in an overestiioafcion of realistic conditions* The 230Th
doses to bone and endosteum were much higher than fron any other
•adiGuucliJe, while •dossg-.t^&ther ox^ans' were similar-rros all- '
radionucUde® that were aeasured* The -aagnitude of the inhalation
2 SOdose from "' Th depends on the solubility of this radionuclide- U
000767
230used instead of class W for the Th dose calculations, doses to
230.
the endosteum and bone are much lower, and the lung dose is much
higher*
la Vivq Analysis
All six subjects who underwent whole-body counting were found to
40have normal amounts of radioactivity, primarily K. LASL
specifically searched for radionuclides of uranium, thorium, and their
daughters and found no detectable activity of these isotopes in any of
the subjects. Because negative spectroscopy results indicate only the
absence of concentrations above the counting system's lisiits of
^30detection, these-limits were computed for the deposition of " Th in
230the lung* The Th detection limit was then converted to the
smallest organ dose detected by the counting system. This ininxmurs
detectable dose, therefore, is the largest: dose that could be incurred
' ' ' " " ' ' 230but not detected. LASL estimated the limit of detection for Th
deposited in the lungs of a 10-year-old child to be 10 nCi and
calculated a miniaum detectable dose rate to lung of 4»0 rem/yr aad a
minirsus detectable total lung dose of 7 * 9 ren» The lung dose fros
230Th was assumed to be the highest organ dose expected from an
acute expoaurc to radionuclides from the tailings pond spill.
In all urine samples, gross alpha, beta, and ganima activities were
found t.o be below the detection limits of the analytical systems-• AU * •t-^- -' --AT **«— :-^A- -
Likewlsca concentrations of total uranium and thorluia, were" below ^
detection limits* When the net alpha count for each radionuclide was
compared wieh the specific detection limit? all samples froa subjects
and controls were below the Units; however, uhen total disAnin were
000768
compared, two of the four samples exceeded the detection limit, vlth
count ratee of 0*15 and O.X8 dis/raini Neither of the control samples
exceeded the limit of detection* The net count data from alpha
7?A 77ft " Cspectroscopy analysis suggest that Ra, Th, and Po may
be responsible for these elevations* These radionuclides are
components of natural background, and are not specifically associated
with uranium mining and milling.
230The limit of detection for Th in urine can be used to esti-
mate the associated minimum detectable dose rate. The dose rate uis
calculated for a 10-year-old child with a daily urinary output equal
to th^'average for the "'Church Rock" subjects (709 ial/24 hr) and an
230exposure to Th that ceased 30 days before the urine was collected
(the assumption that provides the most conservative dose estimate).
It vas also assumed that thorium was excreted in a manner similar to
plutonium. Under these circumstances^ radiometric analysis could
230detect internal deposition of Th that vould give a dose rate of
127 urem/yr to bone surface and 25*3 inrem/yr to total bone mass*
Only in one Church Rock urine sample did the dose rate exceed the^?0£
detection limit for Ra (99% confidence detection limit of 0.34
pCi/1). Interestingly» in four of the six samples the dose rate
actually exceeded the mean of the samples used to calculate the
detection limit of this radionuclide<
r.
itadionuclide concentrations in edible samples from animals were
corrected for reagent blank activity and are presented in Table 2*
The fact that radionuclide concentrations were measured in only 11
- -- .•OP-TS.."•WS.-M..
000769
Table 2» Corrected3 Radlonnclide. Concentrations in Samples ofEdible Animal Organs, Church Rock, New Mexico, 1979
'f;(,
Animal^
CowExposedExposedControlControlExposedExposedControl-1
y
Control-Z'ExposedExposedControlExposedExposedConfcrol
SheepExposedExposedExposedExposed^Controi 1-13Control-2ExposedExposedEx posed1
Control-lJControl-2
ExposedExposed
;gan
IMuscleMiJscleMdceleCtiJbe Steak6
L^yerUveri&U.yerL^crKidneyKidneyKfcFneyBone (Soup)SRq.ne (Sotip)Bq-oc; (Soup)
ti\
HuscleHd,scleMuscleHuscIeMuscle*
Hiti;cleLi^erU^crLt'vcr.i^.Vcrl4vcrKidneyK < el ney
iii'; i .
^
Locatio
JA0PJ
A00JA0A
J0
F
DKI00
DKI
00DK
,^C £...
0,21
0.000.0.3.524.0,300.
10-3.0.0.0.0.
0-0.0.0.0.0,2.1.1.0»410.4.0>
58u
0512
&2
21
9631001 .0200
391813071206049363
120300
( R.-
;-2;
• 0.40
••0.15:0*39':0.443.58
i?^- 0.040.
10.93.
' 0.0.0.0.
0.' 0.0.
. 0'1 o.
. 0.2.
• 2.1.0-
, 0.5.
. 3.
idiom'
^u
28
52
080500
0200
86710841191305084844281931
lC.ltd<E
2:
0.0,0.14Ot0.331.0.090.0.343.0.0.0.0.
0.0.0.0.0.0.1.2.0.0.0.4.1.
i Cone
30%
02
00
00
61
91
11.12000005
2620001 A00
1101021203U3794
;entn
2:
0.00
0.000.000-000.00
0.0.000.6.9.0.1.0.0.
0.0.0.1.0.0.9.0.0.0.0.4.1.
ition
^Ra
80
00859200550200
00000028000060370005002359
(pCi/kg)'1
210pb
0.00
0.000.000*005-44
43.51.127-56
56.2129<
43.60.550.450-00
4.1425.60.00"0.000.000.00
293.43.026.244.834 .1
708.26.1
21C
6.
15.2.573.21
55.7134.
28.24.7
264.654.
159.0.0*0.
12.10.0.I.1-0.
50.28.16.27.30.
457.154.
'po
64
6
7
572526
091149
258328
888
• nEi!E
000770
,(l.JW
•':f,
Edible Animal(Continued) |i.
Radlonuclide Concentration (
Animal^
Shecp(ContiExposed1
Control-lJControl-2
GontExposedExposedExposedExposed
Table
Organ
mied) •^KidneyKidneyKidney
Muse laMuscleLiver
. Kidney
2" Corrected8 Radlonuclide Concentrations in
Locatio^
I00
ELLL
Organs
238y
3.03O.G20.52
0.670.530.560.77
, Church Rock»
234u
2.751.110.82
1 .271.130.530.59
Nw Hfl?dco
230^
26.80.403.95
0.890.25 921.110.07
t
226Ra
601
1
00
Samples
)979
.68
.00
.11
.72
.6 ^
.00
.00
•
of
pCi/kg
210pb
72.80.18.
Q.0.
206.A 71.
^
229
i' "
00 ;;{00 )
i*f,(
•»'••;
.1
'S^,<'!'A
! ' 224,ir 196.•[- 168..'i?^
't*••
£b
;'
J
f
i
'1
i
1
, .
;. 210po
8.508.03
71.9538.
aConce^trations based on gross counts with reagent blanks subtracted; negative corrected.iiconcentrations are reported as 0.00; roany of the lower concentrations are less than ofc'equal toestimated 3.29 sigraa counting errors. ^
^Exposed animals taken from herds known to water at Rio Puerco or pipeline arroyo; conbrolanimals taken from areas distant from the Rio Puerco. '(i.
CLocation on Figure 2; 0 = control animal from area not on map; P == cube steak from Las Vegasmarket; nnte that location A is above the UNC dam hu£ downsrresim from dewafcerfng effluent of U^Cand SCcrr-McGee mines. ;'
"Concentrations based on wet weight. '!^Average between two samples. .'.-^DiiplicaCe sarople- !'.^ Unf£s of pd/soup sample of approximately 1 .5 1. ^Sample lost; 210Pb coneentEation estimated from ^^b^^Po ration from appropriace organ.^Animal exposed primarily to well water from old Church Rock uranium Enine.-^Shcep from area not exposed to Church Rock uranium mining and milling effluent, noted•forreportedly high levels of background xadiation-
^This concentration Is considered £o be in error. See cext for discussion. - ' ;
000771
animals precludes definitive statements on representative
concentrations for the animal population in the Church Rock region.
The following data and discussion should therefore be regarded as a
preliminary assessment of animal radionuclide concentrations and human
77ftingesfcion exposure. As noted by footnote (k) of Table 2^ the " Ra
concentration reported in the muscle of Goat L is considered to be in
error* This unusually high analytical result was noted in the raw
laboratory data* Since the original sample was small, the entire
sasple had been wet-ashed for the initial analysis, precluding a
complete replicate analysis. The only check which could be cade was
222to re^-es-anate - .Hn froro the bubbler and recount it" This x,-as done,
'7"?Awith essentially the same result, thereby verifying that Ra was
indeed in the bubbler. Since this value was obtained, we have no
choice but to report it. However, It appears to be anomalous and, for
the following reasons, we strongly suspect that the sample was
co^taainafced, either during collection or in the laboratory: 1) this
value is over 50 times higher than the next highest amscle
?'?ficoncentration of Ra» and 2) this value is more than an order of
210 210magnitude higher than the Po and Pb concentrations in the
same sample; in only one other sample is radium higher than lead and
polonium, and then only slightly so.
When exposed (Church Rock) and control aniraals were coapared, oost
rsdionuclide - concent ratlo'ns "1% exposed-srsi^bs wer^high^r-thssi' rhoss—-
7'"in '??^for controls* In particular, the concentrations of Th, " Ra,
Pb, and Po in the exposed animals were consistently higher
than those -in the controls. The cow froa station A (above UNC tailing
9 1 ,^-mltSHSrfiJSWV,.^,^-,'-,.. '-U-iato^WJrfMrt,.. Jia .'-n fBr, , - • - ' •^~"» > | i | IMfcH i-— - . -r ci ,.. . t. a.atf.i
000772
daa» but downstream from Kerr-McGee and UNC dewatering effluent) had
i-. i- . ^ f 230-ru 226^ 210^ ^ 210. . ^ ...higher concentrations of Th, Ra, Pb> and Po in the liver
and kidney than the other Church Rock cow exposed to effluent froa the
spill. When radionuclide levels in all edible organs were compared; the
kidney had the highest concentrations, and isuscle the lowest-
Concentrations of Pb and Po were consistently higher than
those of other radionuclides*
Radionuclide concentrations in bone samples are presented in Table
3» Although radiuonuclides in animal bones do not usually enter the
human food chain (with the exception of ingested bone marrow and soup),
their levels provide useful data for evaluating pathway.3 by which
animals are exposed. Additionally» most radionuclides of the uranium
decay series are concentrated in bone to a greater extent than in other
organs and are, thus, more easily detected.
"For all radionuclides, exposed cows and sheep had higher bone
^) *? f\concentrations than controls. Concentrations of Ra exceeded those
210 210of Pb and Po in both exposed and control cows- In sheep,
IIQ 9?5concentrai;ions of ^ Po were generally higher than those of Ra,
except for the exposed sheep that watered from the well near the old
Church Rock mine* There appeared to be no consistent relationshipt? 9fi ?i n
between Ra and Po concentrations in the two goat samples*
210Pb was detected in only half of the samples, and all of these
""concentFatTdns'weri ^esT'Thari^th^s^r'iporf^o "Tor^~ ~ ~~' '^ ^^—^----^^^.
210Po. When radionuclide concentrations ^ere compared by ages of
210 27Athe aniraals, Po and Ra appeared to be directly related to
age for cows and sheep.
000773
Table 3. Cor cteda Radionuclirie Concentrations in AnimalBone Samples, Church Rock, New Mexico, 1979
Kndionuclido Concentration (pCi/kg)0
Animal
Coi;ExposedExposedControl
SheepExposedExposedExposedExposedControl-lSControl-2GoatExposedExposed
aConcentra£
Snmple
Typell. 'l.. • IL-.11..1
1,
1
f;
i'l'murFemur^kmur
fJ
s•I
Unspecifiedif ?murPpmurf*pnurFi*[wirf^tuur
. ;j-Ehtspecified1' .inurr
:iort1
Tibia
i
; based on gros
Loca-
tion0
JA0
FDKI00
EL
Af.c ofAnimal
(Years) 23^
211
3
552889
1 16.3
72.37,0.
26.23.36,43.2.1.
5.
3974
97988803
322
82.41.1.
27.20.3.
42,3.3.
16.6.
21226
1448493°48
926
29.1.
32.
9.35*21.20.34.17.
1 2 .3.
816®9
30894 e
99
784*2
640.2,300.
327.
407.536. 0579.
4,280.354.182.
264.522.
71.800
229.
0
867.32.1
154.0
297.771.290.
1,040-979.667.
1 ,150.1.750.
764.
479.261.
aConcent:rai:io»^l|; based on gross counts with reagent blanks subtracted;negative cort-cctcd concentrations are considered to be ^cro.
i ''T.xooscd animn|s taken from herds known to water at Rio Pucrco or pipelinG arroyo;
control animyls taken from areas distant from the Rio Puerco.^.ocation on ^>>.l^llr(l 2; 0 " control animal from arc«'i not on map; note that location A is
above the? UN^ ( 'ini but downstream from dcwaL-Gring effluent of UNC and Korr-McGee mines.^Conccntrotionii based on wet weight.^stiinated 3.2y siema counting error is equal to or greater than calculated concentrafcion-^Ardmal expose* primarily to well water from old Church Rock uranium mine.SShccp from .icf a not exposed to Church Rock uranium mining and milling effluent,
but noted f o 1 reportedly high levels of background radiation.Sample lost..
000774
Estimation of Human Ingestion Doses
Radionuclide concentrations in animal organs (Table 2) can be used
to estimate human radiation doses that result from eating these organs.
Doses are calculated by assuming particular patterns of organ ingestion
and applying factors that convert quantities of ingested radionuclides
into doses to various human organs (Ki78; Du79). Table 4 lists human
organ doses (50-year dose commitments) calculated for the annual
ingestion of 78 kg/yr of the specified animal organs (estimated average
annual consumption of aeafc by adults) (NK79), or 130 1. of soup prepared
with bones* These conditions were chosen to reflect the highest (aost
conservative) doses to the human tissues that receive the highest doses
from the radionuclides listed in Table 2. Since an individual probably
would not consume only one organ exclusively for an entire year^ doses
have also been estimated for the more realistic consumption of animal
organs in quantities p'roportional to each organ's percentage of the
animal's total edible weight (Table 5).
The data in Table & indicate that calculated ingestion doses to all
human organs were generally higher from exposed animals than fron
controls- Doses from exposed animals varied considerably, however" One
should also note that doses calculated for ingested organs fro® one
exposed cow and one exposed goat were less than those calculated for
control organs- The variability between doses calculated for the
•duplicate-'samples- fToa^n^cow^ll-veT-addltloflaTly •'suggerts-^h^t? -Isrg-er"""-
differences roust be evident before doses from exposed animals can be
said to be higher than those from controls* The highest doses
calculated for ingestioa of a single animal organ were from the
«• .-.. -,..^.——.-,. . , ... ...• i«4ai ^ -. ^ .. M»in ~ .... MUM»»JMritta
000775
Tnble 4. Human Organ Doses3- (50-Year Dose Commitment in mrem)Calculated for Animal Tissue Ingestion,
Church Rock, New Mextco> 1979
Animal55 fOrgan
Cow .'iExposedExposedControl -^MuscleControl ipCube Steak^*Exposed ";exposed ''Control 1 'jjLiverControl 2® -t,LiverExposedExposedControl 'jKidneyExpo&cdExposed ''Hone (soup) JControl Rone (soup)
Sheep 't-'lExposed i'MuscleExposed ';:MuscleExposed .MuscleExposed^ I'MuscIoControl 1^ i Muse IeControl 2 . S
Exposed E.^vcrExposed i| LiverKxposed1 • 1 * T.I ver
Control 1^ S( Li verControl 2 [.Liver
i'
^\ '•
i 1
•
jMuscle•Muscle
. Y.-f v@rI"*""-(Liver
iKldneyjKidney
Rone (soup)
Muscle
ii«1
•
fci
Locatlor^
JA0PJA00JA0A
0
FDK
I
00DKI00
TotalBody
0.50.70.30.37.4
34.52.05.9
58.2117 .6
32.22.50.30.0
3.415.50.11.90.10.1
185.128.016.727.421.2
Bone
0.60.70.50.5
15.585.4
3.314.4
138.9276-2
78.16.80.90-0
8.44 3 - 0
0*14.80.20.2
518 .876.245 .475.357.4
•
Liver
0.92.00.50.58.5
24.24 < 05.1
41 .8100.3
24.80.20.10.1
2.74.60.00.60.20.2
40.511.0
5.48.67.8
Kidney
• , 4.9: 1 1 - 3. 1.9
2.4'i 41.7101.6
20.918.7
198.5485.4118 .3
0.60.20.2
9.310.00.11 < 21.00.7
59.124.914 .623.6
: 24.9
'-
-,
•
Endosteum
0.40.31.30.29.1
61.43.2
12.7163.8286.237.227.40.60.4
8.221.7
• 0.122.10.10.8
379.753.22 1 - 535.927.4
-
Spleen
8.319.43.24.1
70.2168.7
35.831.1
332.5819.9198.9
0.90.40.4
15.21 4 . 30.22.01.61.0
70.337.32 1 - 935.839.3
000776
1.
!i Table *» Human Organ Dopes0 (50-Year Dose Commitment in mrem)Calculated for Aninutl. Tissue Tngestion»
Church Rock, New Mexico, 1979(Continued)
Locafcio^
DK •I00
ELLL
Tota:Body
437.626.267.755.421.0
3.3116. .122.8296.2
L :'Bone
l^Ol-^60.7
168.5
140.644.6
i7 - 9
312,1342-1795.5
Liver
141.224.970.134.028.4
2.55 -7
33.1120.1
Kidney
385.4114 .4173.1148,1124.4
6.710.367.6
425.4
Endosteum
643.062^8
362.068.365.7
34.71»477.2
165.3373.4
• Organ Spleeni •
Sheep (Continued)587.6193.0282.4
^Kidney[.kidney
ExposedExposedExposedControl 1Control 2
t.. Kidney
"? Kidney1^Kidney
246.2210.8
i..GoatExposed"ExposedExposedExposed
. E ^tJf; Muscle:" Muscle'('Liver; Kidney
10.914.494.6
682.9
'' <''Doses calculated for annual ingestion of 78 kg for specific organs (Du79;NR79)»^Exposed animils taken from herds known to water at Rio Puerco or pipeline arroyo;
control animals taken from area® distant from Rio Puerto.location on Figure 2; O^control animal from area not on map; P^cubc steak from Las Vegas
market; note that location A is above the UHC.dam hut downstream from dewatering effluent of UNCand Kcrr-McGce mines.
"Average between two samples.^'Duplicate sample."Animal expo^cl primarily to well water from old Church Rock uranium mine-^Sliec? from (lirca not exposcid to Church Rock uranium mining nnd milling effluent^ but noted for
reportedly'Sligh levels of background radiation'h2]0p^ sarap3q^lost; concentration of this miclide ost-hnntod from 210Pb :210Po rntio from
nppropriiKc organ*
^The measurement of ^"Ra in the muscle sample used for this calculation is considered to beIn error. SGC text for discussion.
000777
kidney. Doses from ingested miscle were generally the lowest, with
the exception of the doses calculated for the goat muscle sample whose
??6Ra concentration may be erroneously high^
There seemed to be no consistent relationship daong human organ
doses that held for all invested animal organs, although spleen and
bone doses were usually higher than other human organ doses. The
highest doses to human organs calculated for ingestion of a single
animal organ were to the endosteum from goat muscle» to the bone f^-oa
sheep or goat kidney, and to the spleen from cow kidney. These data
(Table 4) also suggested that boiled bones in soup would result in
negligible radiation doses to organs of huraan consuaers.
When raw data for ingesfcion doses are studied, inferences can be
made with regard to the radionuclides that contribute the r.ost to
total organ dose. For bone, Pb and Po are the main
210contributory with doses from Pb usually exceeding those from
^1 n *)')f\Po by a considerable margin* When present, Ra is a
substantial contributor to endosteal dose, but raany samples in our
?l fstudy had no detectable levels of this radionuclide. Pb
concentrations consistently gave the highest total body doses and
210 210Po and Pb were the major contributors to liver dosa-
230Concentrations of Po provided the greatest doses to kidney and
230spleen. Interestingly, concentrations o f • ° Th contributed raainly
to endosteal dose and usually to only a small' extent"
DISCUSSION'
We h2v5 presented these data as an example of a strata fcr
claxifying human radiation e.xposure after a docuaenteC rei£'.:ft of
000778
Table Human Organ Dosesa (50-Year Dose Commitment in mrem)Calculated for Animal. Tissue Inges&ion,
Church Rock, New Mexico, 1979(Continued)
Animal Organ
Sheep (Continued)1 Kidney.'•'Kidney^ Kidney''» Kidney
ExposedExposedEK posedControlControl i1;, Kidney
Location0
DK •I00
TotalBody
437.6 1,26.267.755-421.0
'
Bone
201 .'460.7
168.5140,6
44.6
Liver
141.224.970.134.028.4
Kidney
395.4114 .4173.1148.1124.4
Endosteum
643.062.8
362.068,365.7
Spleen
587.6193.0282.4246.2210.8
GoatExposed"Exposed-ExposedExposed
1 1I; Muscle, Muscle:i Liver. Kidney
10.914.494.6
682.9
ELLL
3.3116.4122.8296.2
7.9312.1342.1795-5
2.55 - 7
33.1120.1
6.710.367.6
425.4
34.71,477.2
165.3373.4
''*.^oses calculated for annual ingestion of 78 kg for specific organs (Du79;NR79).^Exposed animals taken from herd® known to water at Rio Puerco or pipeline arroyo;
control ani»als taken fro® areas distant from Rio Puerco.location on figure 2; O^eontrol animal from area not on map; P^cube steak from Las Vegas
markec; note that location A is above the UNC.dnm but downstream from dcwatering effluent of tJHC»nd Kerr-McGce nilncs-J
Average between two saERples»^Duplicate Sciraplo-- Animal exposed primarily to well water from old Church Rock uranium mine.^Shecp from «rca not exposed to Church Rock uranium mininR nnd milling effluent, but noted for
reportedly -high levels of background radiation.h210p^ snmgilc lost; concentration of this nuclidc estimated from 2i0p^;210po ratio from
appropriate organ.^Thc Beasurem^nt of "ISa in the muscle sample used for this calculation ia considered to be
fn error. Sec text for discussion.
000779
Table 5. Fifty-year Dose Commitments (area) forIngestion of Meat in Proportion to Percent of
Total Edible WeightyChurch Rock, :;ew Mexico, 1979
Animal
Expo sedCowCovSheepSheepSheepGoat0
Goatd
Location^*
A
JDXKL—
Tot.Bod-
31
2831
11912
al
7
.8
.7
.4.5.5.6.3
Bone
8,33.5
78.89.03-7
321*032.7
Liver
4.41 * 98-11.90.88.65.6
Kidney
22.3 .9.4
18.04.62.9
.19.315.8
Endosteiun
7.23.5
44.427.83.0
1,412.344.9
Spleen
38.115.925.97.44.7
28.525.1
ControlCovSheep ISheet) 2
000
1.02.0.1 * 2
2.5.2.
119
1-1.0.
019
443
••«
536
222
•••
158
7.66.95.°
^ased on the assumption that muscle, liver, and kidney are consumedin proportion to their contribution to total edible body weight( 9 4 . £ ? » , 3 . 4 % , and 1.7^ respectively). Meat ingestion is assumed tobe 78 kg/yr-
"Location on figure 2» 0 s 3 control animal from area not on map.
Ihe Eeasureroent of ^A-O^ in the muscle sample used for thiscalculation is considered to be in error. See text for discussion.
^Alternate calculation based on muscle ^^Ra concentration forgoat from location E, and other radionuclide concentrations for goatfroa location L-
000780
radlonuclides into the environment. These data provide only a general
indication of human exposure and do not constitute a definitive
statement on the natter* The response to accidents involving the
release of radionuclides into the environment demands this
differentiation^ because limited time and money prevent detailed
studies of all accidents* The results of che screening approach
should not replace detailed studies but, rather^ should suggest the
direction for future studies.
Radionuclides deposited in river sediment can give QOSSS to humans
by inhalation and by ingestion of animals that consumed sediments
while catering at the river. Inhalation doses are predicted to be
highest in areas where tailings sediment has dried and been scattered
by wind and by activities of humans or animals- The data for
inhalation doses to humans from all radionuclides combined suggest
that inhalation results in lower doses than ingestion for all tissues
except respiratory lymph nodes (which are not considered to be
230particularly radiosensitive) o If Th is in an insoluble fi-nr
(solubility class Y), comparatively hi^h doses may be obtained under
conditions of high dust loading. The relatively large contribution of
230Th to total iphalation dose indicates the importance of
atmospheric monitoring in determining acute exposure during the days
icaiediately after uranium mill tailings have been released into the
onvironasnt. Compa'ratlvely-'low eonc€^rEraclons"6r Th'r.sasurd'd in"
animal tissues suggest that the dust from spill materials is not a
major source of human or animal exposure.
000781
The whole-body counts and urinalyses of Church Rock residents
suggest that in this instance acute human exposure to radionuctides
226was minimal Urinalysis for Ka in Nev^ York residents indicates
22 f;:hat these subjects excrete approximately one-tenth of the 'Ra
Church Rock subjects secrete (Sp73). However, daily urin^y excretion
226of Ha by Brazilians living in areas of high natural back-ground
radiation (Pe65) is similar to that of Church Rock residents^ Data
froQ areas of the United States with high background levels of
7 7ftradiation indicate urine concentrations of £a that are much
higher than those from Church Rock subjects (S t -^6) * In the light of
these comparisons and the aforementioned detection Units; additional -
vhole-body counting and urinalyses were not recoaunended for Church
Rock residents"
Four cows (two exposed to mill tailings and two controls) froa the
Anaconda Mill area (approximately 10 miles northwest of Grants, ^'ew
Mexico) had concentrations of ^ Ra^ ^Pb, and t" Po in edible
tissue that were higher than those measured in Church Rock cows but
siailar to the highest concentrations detected in the Church Rock
goats and sheep (Ho79). Rabbits collected in the Anaconda Hill area*)*)£. ^11 (\ »\\ f\
had concentrations of Ra» Pb, and Po in edible tissue
that were generally lower than those in Church Rock animals (Ho79).
Concentrations of Pb and Po in rural German cows (with no
-*lr»du3trial closure) inGlc-at^'-level's IT|- Jfver similar-to Thos® In ""'~~—
Church Rock cows and levels in kicEn-sy lower than those in Church Rock
and control cows (Bu79). Theye reports suggest that radionuclide
concentrations in Church Rock animals may coae from & combination of
environmental routes, including soil, vegetation, and the atciosphere.
. i • i- - i i.iiiiihirii irTm iMli ^TriiriiTtf
000782
Chronic exposure from sources other than the tailings spill is
supported by the fact that the cow froa location A and the sheep from
location I (Fig* 2) had comparatively high radionuclide concentrations
in edible tissues, but these animals were exposed to nine effluent
rather than to spill materials. Since cows from Cemany and the
Anaconda Mill area had concentrations of radionuclides in edible
tissue that were comparable with or in exceaa of those found in edible
tissue of exposed animals in Church Rock, these conceatrations
apparently can result fron £H animal's exposure to radionuclides in
soil and air alone* The tendency of radionuclide concentrations in
77ftbone to increase with an animal's age also suggests that Ra and
210Po have been assimilated chronically, rather than froci the
comparatively short exposure s--o the tailings spill. Radionuclide
uptake from chronic exposure is also supported by calculations thai:
show annual dewatering effluent from Kerr^McGee and UNC mines (with*t')/. i ' )/_
5pCi/l* of Ra) to contain an amount of Ra similar to that
released in the tailings spill. Years of chronic exposure to
dewatering effluent, therefore, may lead to radionuclide levels in
animals that would exceed those expected from the pulse of tailings
liquid released in the spill*
2?6The two animals with the highest bone concentrations of * Ra
were the cow exposed only to mine dewatering effluent and the sheep
that drank from a well-on the--'site'o"f c^e old Church P.ock'urar.iun"'"^
mine- These an.tmals also had comparatively high bone concentrations
?i n •^'3^of Po—a finding which, along with the Ra levels, suggests
that chronic ingestion of aine dewatering effluent could lead to tha
000783
repcrfcfcd ra^ionuciide conce ' ^ re " ^s ir. Church Rock animals that drank
from the Rio Puerco- When th'- bone concentr 'ions in cows e'-posed to
Anaconda Y.ilL taili' •'- (Ho79) are e:-?res -d in terzis of wet weight,
226t V e s e aniaals ^re seci :» I-2ve . 1 — ^ r "'*' ""-a -oncentrati^rs than the
Churrh Rock aniru Is that dra ~ik ni^e ^•: ' "ing -"''lent, b^t higher
concent rs: Lo-'s tha ' "^e Charch Hc-k ar-LniaLs expc-;- Ji co Rio Puerco
210water conLamJ icted by the spi'1.!. The bone concentrations of Pb
210and Po vere higher in Anaconca cows than they u'- •re in any Church
Rock anircals"
In spite of the likelihood that the mine de-^tering effluent is a
cajor route of exposure^ we did not clearly identify the primary route
by which Church Hock animals were exposed. The clarification of
exposure routes has been particularly hampered by the absence of data
m n ?i non concentrations of Pb and ^ Po in the dewatering effluent of
the two nines^ More enviro resent al and autopsy data are» therefore,
needed to establish the extent of the irigestion and inhalation
exposures to both humans and domestic animals*-
Kegar-Uess of the route of exposure, the main contributions to
210 210human ingestion dose appear to come from Pb and Po and not
9 ^Afrom Ka. The current treatment of cine water before it is
' ) ' y f.released into the river system removes only Ra. Before consider-
ing ef forts toward reduction or Pb and Po in animals, the
relative contributions to animal radionuclide burden of inhalation,' of
soil and watfesr ingestion, and of foraging should first be clarified.
Human intake froro food crops or from eating bone marrow should also be
more thoroughly evaluated
000784
A review of state and federal regulations that pertain to the
ingesfcion doses caZ^ulated from the Church Rock data indicated that no
exposure limits were exceeded by the spill, or through chronic
exposure to mine dewatering effluent (IC60, FR61, EP77, RP80). Some
of the calculated doses were high enough to suggest further
monitoring, however* A sampling program designed to clarify the
origin of animal radlonuclide concentrations has been re contended, and
may lead to technically feasible reductions in animal exposure»
particularly if cn-ne dewatering effluent is the major source of
exposure. We have also suggested that Church Rock residents' exposure
to radiation can be reduced by eating less liver and kidney from local
animals? by not drinking from veils known to contain elevated levels
of rad:f.onuc tides i and by avoiding the banks of the Rio Puerco when the
weather is dry and windy. The reported radlonuclide levels and human
doses, as well as the uncertainty over the sources of animal
radionuclide concentrations, underscore the need for thorough
radioDucllde monitoring and dose estimation both prior to and during
the operation of all nuclear facilities.
Some unique conditions illustrated by the UNC mill accident are
discussed in greater detail elsewhere (Ru81). These conditions
include the contamination of a river system by both mines and a mill,
the siting of tailings ponds near a river system, and the watering of
'local aniaal' hercTs"wiTh~ uranium' Ki-ne~dewateri^^-e'fr^uent•^'"T^ese"""' ~"~
situations point to the limitations of "generic" rsdiobiological
icpact statements designed to reflect conditions at all uranium
mills. Tney also suggest inconsistencies In the current federal
000785
population exposure regulations which exeapt uranium mines, exposure
y i 1 1 Z i U210, 210.from radon and its daughters (including Fb and Po), and
exposure from accidental releases.
The need for a cancer registry of persons exposed through the
Church Rock spill came up often during our investigation- This issue
has been explored by Ruttenber and Kreiss (Ru81) and has been widely
discussed in the recent scientific literature (Go75, HB80, and La80)<
Briefly? the usefulness of a registry depends on an accurate
assessment of radiation doses for each registrant, the likelihood that
these doses are sufficient to produce detectable ffiorbidity or
mortality, and a population of adequate size for detecting possible
elevations in cancer mortality. Though the first condition may be met
for Church Hock residents if an extensive environmental monitoring
program is established, the estimated population at risk for exposure
is less than 400* In the light of the currently known cancer
incidence and mortality risks associated with levels of radionuclides
measured at Church Rock and at Galiup, we conclude that the exposed
populations are too small for investigators to detect increases in
cancer mortality with acceptable levels of statistical power. In
fact, it may be Qlsleading to establish a registry with the
foreknowledge of a low probability of detecting mortality increases*
000786
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000787
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000788
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25
000789
Captions for Figures and Tables
Figure Captions
Location of United Nuclear Corporation (UNC) Mine and Mill,l ew Mexico» 1979
•ig. 1
Environmental and Biological Sample Sites, Church Rock, KevMexico, 1979
^lg- 2
Table Captions
Table I* Detection Limits for Radionuclide Analysis of Aniaal Samples,Church Rock, New Mexico, 1979
Table 2- Corrected Radionuclide Concentrations in Samples of EdibleAnimal Organs, Church Rock, ^ew Mexico, 1979
Table 3* Corrected Radionuclide Concentrations in Animal Bone Samples,Church Rock, New Mexico, 1979
Table ^. Human Organ Doses (50-Year Dose Comziitment in larem)
Calculated for Animal Tissue Ingestion, Church Rock, ^wMexico, 1979
Table 5. Fifty-Year Dose Commitments (mrem) for Ingestion of Meat inProportion to Percent of Total Edible height. Church RockiNew Mexico, 1979
000790