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

REFERENCES

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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

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