ML20037B724

Natural Radiation Exposure in Us

ML20037B724
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Site:	Dresden
Issue date:	06/30/1972
From:	Oakley D ENVIRONMENTAL PROTECTION AGENCY
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ML20037B722	List: ML20037B721 ML20037B723 ML20037B724
References
RTR-NUREG-0683, RTR-NUREG-683 ORP-SID-72-1, NUDOCS 8011100091
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Text

.

i NATURAL RADIATION EXPOSURE IN THE UNITED STATES i

r I

Donald T. Oakley l

i i

I, h

s June 1972 7

U.S. ENVIRONMENTAL PROTECTION.tGENCY e

0:' ice of Radiation Programs Surveillmce and Inspection Division W.uhing on, D.C. 20460 B on i oog g

i a

CONTENTS Page Chapter iii FOREWORD v

.\\CKNOWLEDG31ENTS is LIST OF FIGURES si LIST OF T.\\BLES.

xiii

.\\BSTR.\\CT..

I 1.

INTRODUCTION I

1.1. General I

1.2. E-timates of natural ridiation expmure 2

1.3. Sour.es of n stural r.ni!ation expesure 3

1.4. Methology

2. - COSSIIC R.iDI.\\ TION 5

5 2.1. Introduction 5

0.1.1. Galactic radiation 5

2.1.2. Solar radiation 5

0.2. Cosmic ray variation 5

2.2.1. Time variations 7

.. ~..

2.2.2. Latitude variation

'3 2.2.3..\\ltitude variation 9

0.3. Cosn150 ray nien5Miements.

3 2.3.1. Ionizing component.

10 0.3.2. Neut ron cumtw,nent.

11 2.4. Population distribution 13 3.

TERI'ESTRI.\\L R.\\DI.\\ TION EXPOSURE 3.1. S mrces 13 17 3.0. Var ations. : terrestrial radiatien 17 3.2.1. Radon itaughter pmdans 13 3 1 2. M oi-t.re.'.

-r.nw cover 19 3.3. Men nents 19 1.3.1 G und -urvey=

21 112. De-e equis aient ra e due to fallout 22

' 1.3..\\erial <urveys vii

.s

L'hapter Page 4.

N.\\TUR.\\L R.\\DT.\\ TION EXPOSURE OF TIIE U.S. POPUL.1 TION...

33 I

j 4.1. E x t e rnal : on rces..............................................

.... 33 i

4.2. 1ttennation of esternal snurees............

33 4.2.1. IIou<ing

-35 l

4.2.2. Biological shielding 35 4.3. Internal smrecs -

36 4.4. Dose equivalent to the gonads and Lonc marrmv..

36 4.5. Discussion....

37 8ODf.\\ R Y 41 HEFEDENCES 43.

.\\PPENDICES 47

.\\ppendix.i. Cal.ulation of average dose equivalents due to terrestrial and 49 voitnic radia' ion

.\\ppendix B. Etieet of building materials t.n exposure 65 i

.\\ppendix C. Calen!ation of 2, error of total dose equivalent 67 b

4 i

a r

i E

V t

I 1

I

.i l

I k

i e..

k nn,...--~.-n,

t 4

ABSTRACT The esposure of man to natural radiation sources in the United States has been esti-mated by considering the distribution of the population with respect to certain factors, principally geology and elevation, which intluence exposure to terrestrial and cosmic radiation. Data obtained bperial surveys.:a the United States have been used to calculate an average'{6srequivalent JDEEntiliiil'e3fyl em/yr. to !!ie Fo}ulitl6d The results ik also indicate three distinct aresrof terrestrial'rndioactivity h the United States-(1]

the Coastal PITinTElili:h cons:sts of ill'or por'ti6ns of States'irom Tesas to New Jeney (23.si5ilifyE); (07 a portion of the Colorado Front Range [(p0 hiisiiRfM; and @lthe rest of t':e UnitedTtates,ie, ptions of the United States not included in 1" or "2

06]Since'eleratir2Cil the primary dCecai:pnt.of co<mie.: 27-DE in the United States, n:L yr).

_/

the population distribution with respect to elevation was determined. The average pop-ulation elevation of the United States was determined to be approximately 700 feet, and i

the average cosmic ray DE was estimated to be 44 mrem /yr.

To arrive at an estimate of the gonadal DE, the influence of housing, biological shield-ing, and the DE contribution from internal emitters was aho considered. The first two

. factors serve to attenuate man's gonadal DE due to terrestrial radiation by about the same amount that is contributed by internal emitten. The yvefige. gonadal DE.to thel U.S.-

' population w33'sateu!ated to be ys mrem [yrr;

s. L w

siii f

~ ~~~

k

. _ _ _ _ _ ~ _ _ _ _ _ _ _ _ _ - - _ _ _ _ -

t h

a I

NATURAL RADIATION EXPOSURE tr IN THE UNITED STATES '

l t

i it Donald T. Oakley

• f t

CHAPTER 1. INTRODI'CT'ON T,

t tention which has been accorded to sources of less 1.1. General magnitude cnd ubiquity. Ilowever, in order to The largest source of ionizing radiation expo-determine the significance of the effects of email i

manmade increments of exposure, it is necessary sure to the worbrs Impidation is from the natumi to determine the brger conq.onent due to natural i

radiation enviromnent. This expo-ure is by no radiation. Examples of studies which have shown means uniform for all individuals, but varies he.

correlation of background radiation with cause of a number of important factors: altitudes, health are Grahn and Kratchman (1:nti) and no geological features. and livine habits of man himself. Variations in exposturs as a resnit of Segal et al. (1004). Although studies performed 2

t!.cre factors often exceed expo-ures from sources by We-ley (1960) and Gentry et al. (197,9) show which have recched considerably more attention.

a variation in con =enital malformations with

.\\ccoriling to the existine literature, the geneti-background radiation. a ierent review of the lit-cally significant Jose equivalent (DE).Tra3i]id erature by Sagan-(1971) c.-te doubt upon this teiation< hip. Backcround r:nilation expmure is h6d7:n!!'a~thd in the United States Fairce ' from ho to Eituremfytj The average itali5ddiliiving ! css ucH defined than smaller somres of espo-nre, and thus may contribute to the deleterious in the t~nited States in 104 received an x-ray esposure DE of 55 mrem!yr. (l'.S. Public edects of radiati m which are speculated to be associated with fAlout, nuclear reactors. and x 11eahh Service. IN9). Other. mrces, such aa nu-c! car reactors, fallout, etc., acconut for less than radiation.

3 mremfyr. Within this perspective, the purposes of this stttdy are to better e-timate man's exlo-sure to natural sottrees of radiation to investi-1.2. Estimates of Natural Radiation gate the variations that '

r. and to examine the Exposure parameters that intlnenct.,oth the levels and the variations so that the relative importance of Measurements of natural radiation background manmade espo-ure* may he evaluated.

pag e been performed worldwidet within the It is frequently stated that man has endured t nited States measurements tend to fall into and thrned m Ins natural environment. Thu' three categories. First. there are single measure-th,is source of exposure has not received the at-ments which have been made at willely varying locations. The locations may have been chosen on

1. "",." "Y.to !aWWy bSks.

' t " c+ *moed to the Fx.dtv of the thrvard S hool of interest t?! t':e 1mo pu tivity of variouw ;eoloe.lcal Mtw licahh in parust fauiltrnent of the regmrements for the fm mations. or intere-t in determinine the pres-ce of Decor 3f S ience in the ticid of Enurenment21 eNe of nuh wqm fue TW mW m Je N'jIlh S'"N#5--I't. Don.!J T. Oakley n De;'uty Director of the Suneitt.,nce tenin e measurements of tlu.- type m the i..uned Enuromnental Trote.twn Agney. RoeLulle. 3far3 kad. ~

States have been reported by the llealth and I n s pection Dniuon. Office of RadLtioa Procarns, and 1

~ _ ____.

.g Safety Laboratory, l'.S. Atomic Energy Com-fallout to the total DE. The measurements by mission ( AEC) (Beck et al.,10Giab: 1000ab).

IIerbst, which were made during 1957 to 1000 and The second category of measurements has resulted in IMI. respectively, are probably most in error from special studies, which have been conducted on this account, since fallout contributed as much primarily for the purpose of estimating :$

as 30 percent to the total external DE rate during

[royd7dEifiogexpfg:r] to the population.

these periods.

I'xamples of this work include FudieriaTeJr EdaW FSGalEIGOSDR._Lorisdn3 1.3. Sources of Natural Radiation

[Grtdonjl105U and measurements in 24 Stshs Exposure by Levin et al. (1905). The third catecorv con-I sets of aerial surveys which have been perf'ormed Exposure to externalha'H'il hid!ipon $rcej by AEC and its contractors around nuclear in.

occurs through(idsmic~ radiation srd 'rsdi62ctivei st.!btions within the I~nited States.

Gre':Weius'"n ihe~ earth's'entit and.in Luihl.ing _:nny.

In c.creral other countries, surveys have been 3erials.'An additional it.mment of external expo-performed on a countrywide basis for the pur-sure. which aecounts forless than #Fer3eiifEf tfie]

pore of estimating the population exposure to total, is due to the presence ofiTdioacdye decay; natural radiation f t..i,le 1). The investigators produefaof bdhri'and th5r6E in thf'aVineschere.

The natural rad.... - = ---- ~ - -- J have employed diderent techniques and instm.

iation environment has been memation da that a direct comparimn cannot be relatively constant since at least the beginning of made. IDwever. even if we consider these factors the Neolithic Ace (10.000 B.C.) and prob.bly for and the di:fering emphasis on measurements much longer. The most recent rever<al of the (open ecId vs. paved areas. indoors vs. out.

earth's magnetic fie d occurred 700,000 years ago, i

doors), there is reasonable agreement among the and at that time the cosmic ray intensity may e-runates.

have increared by 10 percent in equatorial regions

.Tieasurements obtained in the I'nited State 4 of the carth for approximately 1.000 years will be prei.cnted in ti e following chapters. and it t Illack, INT). With the exception of short. term will be -een that they are <imilar to mea <uirments variat:ars in cosmic ray intensity, there is noth.

oi.tained in other countries (table 1). It shouhl ing in the hterature to indiente the occurrence of be noted that the mea;nrements by lIultqvist significant changes in natural radiation sources (10M), IIerbst (IN4), and Ohlsm (1000) were einre the most recent magnetic fiehl reversal.

made wi:h either ion chambers or portable sein.

Although the intensity of natural radiation tilbrion 'e:ectors, and therefore the measure.

-ources has remained constant in recent times, j

inents include the contribution of mielear weapons man's living habits have changed in such a way Table 1.

r.mtes of dose equisatent due to terrestrial and cosraic radistica in ser rst countries I

Do-e em:f ratent e n.can t r.rfe re r.ce C mntrT

. m rem /yr.)

Retnarks i

!!altqrtst. IM6 s e edeo

!! we+1 Jwen!ngs M*wara r: ants at centers of reierns In MC apart cents. 6tf 150 t. rick

'swa-.

i n u lud or* * : auther

• ratues of ton pairs /

I Iv* concrete rm' - e. min ert.d to mrern/y r.. aauming 1 ton pair /

e na8-.cc = 1M or u/hr.

He-*st. IN4 5 = t!:cr:and 1:a C-ttm.1te waf 3ta l be atit-ttmit'ns of pnts:!a ten over i

are.iegtent regten, and.td

• r/ cut h r ati:3nucy Yr.m;v,

.! I rs* tit.

Ja p.in

s. !!

.ity -c for r..t2..tum, wrat t rn. and ther am at e

= a. I 17

.'u ; = i

• t..n * :.n-int :*rr -t rtse lit; = 47 :r.r. m/s r. : if w-1.le DE = 40 mretn/yr, fors! = '? mrern/yr.

j t L t.

1 ;5 R.a many M

. + 1.n.

a. rteia.

e t.o.ir.

n. n. i... m est, snooers :

. "m te (* wetd.ra.s by time pent toters and out-4 j

d. -rs t"r* ; r. r d *!. w : ! ? 7.*

• !sra n u. rs := af 'rr&.'. ~e't ts a t OC mt ier toc 1 *t 'ns = 72 m re?.s/.s r. i t-tr. r-* 11 mi rees i r.:r t : if ce-mic rar DC i,

is c.staed to te 40 mra 1/,s t.,

ves! = 110 mr*m/yr.

a g

,. -.., ~ _ -,.

w--

-- ~~---i -=

w

s by md as to influence his exposure. Populations he e 1.4. Methodo!ogy tended to migrate imm coastal to inland areas, ror teh thits inereuin*a their elevation and exposure to One of the pr.nuary obj. tives of th.is -tudy was ec.

ng cosmic rad..iation..\\t the same time, the outdoor to estnuate the external nitural rad.iaih n expo.

agrarian society has largelv b;e't Itplaced by.

mte tate 4. l.a sure to the population of the L.. d s.

In-door work and life.m urban centers. Man. expo-do so, ex. tmg dats on terrestrial and cosmic s

is.

sure has tlms been. increased in some instances radia' ion measurements weir con <iden d.m licht because of the nataral rad.ioactivite of bm.ld.m "-

of population d.irtnbution and i..n mg halsta.

materials:.in other instances, bm.idmgs attenuate Many mensmtments made for orher pur.e mn.

expo 8ure to the outdoor terrest rial soutres, itsult-tribute mformation un man. expo-tire to saq..t-tion from ea ural sources. For example. ime,a_

.m-m lower exposure.

.t

.tithough th.is d.:ssertation is prnuart v con.

of the ex.istine data on ecsmic radi tion exre :re it eerned w. h external rad.iat.mn sources, it is im has resulted from.mtere+t m h..ien-enerey pante e portant to note that p,ddit...l-..._ _ ts_o..f T)N.-reactions or from studies of cosmic ray variation.

iona menmen c

result,. rem inge-t_ ton and. halation of natu.. l

. *IG 5dienuclides. Pot.assium40 is !Ite principal conj 3**"* h*I"*I' ~ I* ' 'I"f#0*ITI'I'~.c w m

ra m.ated py.h eyt =ce_urm,B tribritGf Tide'rtGI DEibGr~si5ificant insrnas b"'ms may be er.

t

~ ' ~ ~

'.c leujawd from chemical asnys of natuul I

emitte s are 'rndism-220.and -22S.. md thes emtuns ut soit Gmund analpes and soil anaiyrn.

' daughter products...carbin'.1Fand rido5222' li wevet. have n t been smhetently exansive m (CNSCE.\\R,1902). Gonadal expoiu'r~e to ex-make an overall estimate of extyocure m tl.e ternal radiation is about five times greater than t mted e,tates. yor th.s rt son, the e-t: male,9 that from internal sources. and the ratio is simi-

!ar for expo <ure to the bone marrow. With regard "I**"#'..due to terrestnal sot.rees jn tins stnN gel:es, pr:nc, pally on data Jrom aerpst pr eyj.j i

to natural internal radioactivity, Cherry et al.

Ge aenal surveys. w,meh_ were prev;ousiy men.

(1970) have reentiv shown that man has rela-

'I ned, have been made over areas ae. mss the tivelv low concentrIitions as compared to other L. ad States and all together cover land atva<

m mammals. dsh, and birds. In fact,in a comparison occupied by approximately ^.0 percent of the L,.e.

of total alpha activity'in the bc I of 1S ditierent t

P P"I^'I "*

mammals, only the pig ranked '.ower than n.an.

A combmed e-timate of the tmal emmie tay From their analysis of herbivore bones and ma.

am1 terrestnal DI.. was then mao,e m '..m

-n:..t:-

rine livers. Cherry et al. prediet DE in excess of en the basis of what is known cernine the di-.

1.000 mremfyr. to these organs, of which 00 per.

tribution of the population by eierathm. ee<douy.

eent or more is due to internal alpha emitters.

The retention of inhaled radioactive daughter and h.mg habits.

Units of radioactivity have perplexed practic.

products of radon and thoron is the primary in; health physici ts and those recomm.. d.:..

sonn e of lung DE to the general population..il.

thoueh the inhalation of radon dauehters has units since the discovery of ionizine radiath.n..\\-

a result, it is common to find Indts of [.PijgG 1 cen gis en rpecial attention in t te ease of ura-i nimn minets (Federal Radiation Council INT),

tradd,~rJreme u.c1 to de-cril e the -:une thine Mm expmure to occupants of residential dwellines radiation protection literatutr.19er-WiM. Q r

~(1%G) caleu-tlIrec en.it.e= are appr'xn.:eiy 5p afin' * - ' '

can also be <ignideant. Ilultqvirt

' eed a ptestia! iie~ rah Emg dse of 34pdinl of jerniziii.t.' di.d.E frdi;i D.:ern d_; an nl * - ;.

of DE.

~

7 tind' LT6~e ' and there: ore d.e mut 6

yr. to occupants ot iiiventilate<i wood.3 weilh:;s 1

and CH adilhvm/yr. to _ occupants'of' unventL-the rem is u-c.i thronuhout f t!.e uc of un.-

bred i:.. rete trulding..he m eati.i, Les

,rmhy. A fnN A-4

pt 6u of a-unc eims

~

vi /..e i c -n et 1}. t, WII) Itave found that dret-Wr occilpailti may ite fonnii in ( e i.hcr of frame dwellings may receive a hmg DE of 1.30 men &.tiom of the u.:caa'.md C e:--~

o, mrad yr.

• rom alpha emitters. If a quality factor Radiation Unit < nnd E -n r :-, i< al' of 10 is awumed. then the DE is L:.00 nurm/yr.

t w?I).

• h*um.-

l r.

c.

r e

i

~

CHAPTER 2. COSMIC RADIATION cent of all flares belong to class 3 (the largm) 2.1. Introductiort (Langham,1067). As will be discussed later, the p-inue ragtcr,is composedtprimartl--of...S relatively low energ*y of the solar particle < 'm.

e y

e

.saette radiat:or and a varving component./b..f tolaF>ciudes their secondary radiations from reac..nme s

. ~ - -

ratua wn, Galactic rad.iation originates outstde of the earth's surface in all but the largest flares.

our own solar system, nd, as the name imphes, solar radiation results from phenomena on the 2.2. Cosmic Ray Yariation

' n n.

i 2.1.1. Galactic radiation The factors which contribute to cosmic radin-The primary component of galactic radiation.

tion variations are extensively reviewed in books as it impinges on the earth's atmosphere, is esti.

by Rossi (1964), Sandstrom (1965), and Haya-mated to be 75 to 50 percent protons.10 to 15 kawa G063). A brief summary of the presen-percent helitun nuclei, and 1 to 7 percent nuclei knowledge of cosmic ray variations is presented with Z h3 (UNSCEAR,1066; Neher,1067). The here in onter to justify the dose estimation pro-energy range is thought to extend beyond 10" er, cedures which follow. In addition. knowledge of and the avefage energy flux arriving at the top of the many variations which exist is helpful in the atmosphere is il x 10' MeV/cm:-sec. (KortY, understanding rather large ditierences in the 1061). In addition to heavy particulate radiation, electrons and x rays have also been detected in reported measurements.

Primary cosmic radiation.

Primary cosmic ray interactions with the at-2.2.1. Time variations of mesphere result m an tomung component The temporal variation of cosmic radiatica has cosmic radiation in the lower atmosphere, pri.

been observed for approximately 35 years, com.

marily muons and electrons, and a minor neutron mencing with the work of Forbush (1935). At component. The process of formation is shown that time. Forbush reported the etfect of the " sea-schematically in fleure 1. Of most sienificance to sonal wave" cn ecsmic ray magnitude and specu.

population exposu're is the formatio'n 4f mTiE,}

lated upon the possibilit,s of the influence of the which are generally assumed to WMit for apj fieximLtely 70 percent of the~ecsmic ray Ilde at]

solar cycle ca cosmic ray intensity. Research thus

~

' ~' ~

far indicates that mo-t variations in ground-level

'Teh 'evej (Lodder"and Beck,1066).

cosmic rav intensity are attributable to solar influ-

' ~

~

2.1.2. Solar radiation ence on the interplanetary magnetic :leid (For-Particulate solar radiation is comprised almcst bush, 1054,1055 : Kuzmin and Skripin,1066a:

entirely of bursts of pretoas ad helium nuclei Pal,1067). In general, where cuiations are attributed to solir influence, the ionization inten-Wrh enerpes ranging up to se.eral GeV. The proten 1 urets. or : tares. follow approsimately c

+ity on earth is im ersely correlated with tolar l'e" cent of the herved sunspots. and about 3 per activity.

5 gg f%.a

e t

eteaar c:!s; par WCLit e g e.; c...

.s,

,* * ! a.

• isC 58. n e t t

L l

f l

t t.

?-

F.

w e.t:= :*Ka:Es I

7,2 5 a :3 ' 3E:1 j 7.la W e!E:1 F.... ? > * * :: c's t

r.- so s l

. n % c.t:=s

-y3 I

t I'

d t

f t. l*

\\

?

, 7 2 2 a :3 * !ECS r +i g

..c-s

,:g.

9 u r ses y :.. e..s e

w. : e s Fi;ure 1.

Formation of connic ray secondary prc.direts Y

t' in5'In TJ-:uid3ti.atisn ha've been~oh:

T':e ground e:Tect of a 3* flare is shown in fig-T !. ' :o....tr in c.w:es vf 11.v.ca.r.s>' 1 year. :7 nre 2..\\!thouch other !! ares have had a more nro-

-.. :<i 1 lay. ::nd Neher (IN1) haa recently nounced :emt,orary edect on neutrna 'evels, the re' ' eil ',..e er:tte: ice,or 1 eycie Wnten persiS*s

,ac,K of s.!gnincant in..nence on f.ue lon ci.rlmber 4

-. ii 11.mr u rio k.is a re-nit of the-e measurement is typicsl. Following an initial rise

n neutron and muon,onnting rates, t,ue,.evels

... :a 2. :en..tv of _:...e -:crel.:vn :at:nn at.

..".a may ti:1,sy.epres::natelyA.. - are observed to u,eereate wet t,ne pre,.are values.

,,..a-et on :,.e con <itieration n,.

emmic

. twonactistes on the e:ttth and in

..c.,

.. Ilay sawa t I?O) awris that averate

'e cis have : vin. tined Ivlativel.v con-

.v n.

at 'e.:-t '# years. Ma.xi:nnm leveb prob.

..s. E

>C c,I in:dag the ret t r-ds of the ma::netic y

J 8 0 4 3 U19 O E C E E 4 5 E l

a

..s

.p>* ;c' e!J o! u nien acc'irred T.V'%I,.

g 10 e.N i

L l

=

,'t

. f t.

S'!itan an :llereCh* of

• .3I {ieTeent nlay

{

8 d, )

y '6 [

"J

'* E u " 4 4

' r'- 'd I } h,a e <.

rH. - ).

3

.. u J

. ' r tare-. ccur :nore fic.pently during the w.E

[

j

..i a

sm :r :am:.uun permd or. he 11.vear eve:.e.and t

4 l

l

-1

• .re +! ares :'t e al-o ron-der ed here as a tem-

1.0 O'sC auBEe -

,+r3!

i i r at b >n..\\ith.dtgli *be !1aiaDl.,to -pace

c e

nur:ng *n:s t.ie 6d are note?lt :a u,r.'reat

. J,

n. :! M L neham. W7: II:dner. IPC.

i 1

vt

c rent c f the e trth anti.,t ue -:ne:iunc 3

10 12

'4

't

• 3 20 27 24 w ait t;.:e it h o-phet e re-alt m,.itt.c Per-3 JAY 'Of7 iM o r' t }R' -e:'- CYel :.ie:.-Iry tlMTm g F ** a re.

.u

,n:c-to lla;ner

...M..-i.

e,es en 2

F.i;ure.- Co<micr23 ;ro"nd 'es el measurene ts mar-

.c-

, t ;.e I ;c-t

,$ - 1 rnt ca.g

.e in: 2 3 - th re. L kut,

l'.S.S.R 51* ;om a g etic 61 ' r: :c i of

.amn -~ a r acS :ty.

!atitude (Kuzmin ud :2kripin. Imb)

.- i

central Oregon). However, it.<till appears that the inf!nence of latitude on cosmic radiation ex-ai

1. "~~~*"

posure within the I'nited States is negligible in 7

I terms of population exposure.

[-

.ntereen

, ',, ~ ~ ~ ~ ~ " "

Neutron !!nr varies by approximately 00 per-cent between the poles and the equator and by

/ /,[,, e-- -wurnom '

f l

15 percent within the range of latitudes covereil

~

by United Sta 's (I'NSCEAR,1960). Ilowever,

/ / j'/

i since neutrons account for a small fraction of the g

////

total cosmic ray exposure, the variation of Di' j

/

f/f' //

with latitude in the United States is insignificant.

m :a' -/

Furthermore,in a comparison of cosmic r'ay meas-3

/

urements in section 2.0. it will be seen that uncer-i j

.-g rainties in the v:.rious measurements tend to s

/

[

N obscure all variations except the increase of expo-j f

/

(

l sure with c!evation, and, for purposes of dose g*, 7

~

estimation in the precent study, the latitude j

~ n

[

variation in the United States will be neglected.

,f e 2.2.3. Altitude variation a

'I e

• • C t"t * "*

3 -iii i f

T'je atmoirhere atte: mates the ecsnu.e ray aun, the attenuat.sn of the secondary particles is jj f

varied so the relative DE contribution from dif-

/

ferent particles changes as the atmospherie depth

,/

i increases. As a general view of cosmic ray DE a

z e

s a

I variation with altitude, a summary of O'Brien and 3IcLaughlin's (1970) calculations is pre-sented in figure 4. In their work, O'Brien and I

rir re 4.

Cosmic rar dose equitaient rate variation

.'fcLaughlin have 'shown that the calculated with altitude (O'Brien and McLaughlin,19to) values aeree well with mensmed ionization values i

throughout most of the atmosphere.

The ionizing ecmponent of cosmic radiation nentially with pressure with an e.fohling thick-in the lower atmosphere has been measured by ness of 165 g/cm, or a half thickness of 114 g/

2 werkers at the California Instirnte of Technol.

cm: ( Patterson et al.,1959: 3 files,1061). The t

i ogy (Bowen et al.,1034: 3fillikan et als 1936b:

constant slope in the lower atmosphem indicates and Georce.1970) and the AEC IIealth and that the neutron spectrum does not change over Safety Liboratory (So!on et al.1900: Lowder the same mnge, and therefore in this report the and Beck.100G; and Ra ft et al.,1970). The ioniza-neutron DE is aisnmed to vary as the neutron.

tion proilles (ionization vs. elevation) ut. to 15,000 density.

feet as obtained by each invest' gator have ap-C!osely related to altitude variation is the vari-proximate!y the same shape, the primary ditTer-ation of cosmic rndiation with baron.etric pms-ence being in the absninte vaines. ihe protile sure at a fixed elevation; Shamos and Libotf determined by Lovder and Beck (1906i is repre-(1066), in addition to their own work. have re-sentative of the existing infccmation and is used viewed the findings in 21 investigatiens concerned to obtain the DE s ariation w'th elevation, with this erre t. The "hard component" (primar.

l The neutron contribution to the co-mic radia.

ily muons) varies by at;ont 0.17"c torr, and the tion DE is approsimately I'. percent of the tr ml "mft component" has been estimated to vary by and will b diuwed further in the r. ext section.

alent 0.03"c torr. The overall variation is 0.3 to Neutron dentity in the atnnp!.cre varies expo-m torr. For purpo<es of lone term estimation, i

5 i

ne

a central Oregon). IIowever, it still appears that the induence of lar:;.de on cosmic radiation ex.

a' posure within the U:.ed States is negligible in i

terms of population exposure.

- - gt:

aus l

Neutron flur varies by approximatelv 30 per-

• e cent between the poles and the equator and by

/

,e

/.f,//

-enous -

15 percent within the range of latitudes covered

//

by United States (UN8CEAR,1066). Ilowever,

,/ //,//

t since neutrons accotmt for a small fraction of the

!j'/

total co<mic ray expresure, the variation of DE with latitude in the United States is insig'ay m nificant.

rw _ff' Furthermon,in a comparison of cosmic r

,/

,/ f '/

eas.

urements in section 2.0,it u !! be.-een that uncer-i

/

/j//j

[egN 1

tainties in the various measurements tend to y,

I obscure all variations except the increase of expo-I. _/',7[j/

/ //

\\mcm sure with e!evation, and, for purposes of dose g 'e a

a l

4 estimation in the present study, the latitude s

variation in the United States will be negierted.

8 c

o 1

2.2.3. Altitude variation I

" " C'"*"**

f

/

T'; e. _ _. _.___. -afmesphere attenuates the coinEray,fl.a_x_y the attenuation of the secondary particles is

/'I/

varied so the relative DE contribution from dif-

/

~

ferent particles changes as the atmospheric depth

,/

increases. As a general view of cosmic ray DE o

2 e

s a

u variation with n!titude, a summary of O'Brien and McLaughlin's (1070) calculations is pre-sented in figure 1. In their work. O'Brien and rigure s. co,mie rar dose <quivalent rate variation

.'.icLaughlin have 'shown that the calculated with deitude (0 !3rien and.stetsughtin,19 0) values agree well with measured ionization values throughout most of the atmosphere.

The ioni:ing component of cosmic radiation nentially with pressure with an c.fohting thick-in the lower atmosphere has been measured by ness of 165 g/cm2, or a half thickness of 114 g/

I w3rkers at the California Institute of Technol.

em8 (Patterson et al 1950: Milea, 1964). The ogy (Bowen et al.,1934: Millikan et al.,1036b:

constant slope in the lower atmosphem indicates and George.1970) and the AEC IIealth and that the neutron spectrum does not change over Safety Laboratory (Solon et al.,1060: Lowder the same ranga, and therefore in t!!s mport the and Beck.1MG: and Raft et al.,1970). The ioniza.

neutron DE is assumed to vary as the neutron f!an proSics (ionization vs. elevation) up to 15,000 density.

feet as obtained by each investigator have ap-Closely relat.'d to altitude variation is the vari-proximately the same shape, the primary di:Ter-ation of cosmic radiation with barometric pms-ence being in the abs <1ute vaines. The protile sure at a fixed elevation: Shames and Libotf

.letennined by Lowder and Beck < 1066) :s repre-( DC6), in.nblition to their own work. have re-untative of the existing infonn an and is med viewed t!:e fimlin:ra in 21 in.cstigations concerned I

to obtain the DE variation niti. < ievation.

with this edect. The -hard component" (primar-The ^ **-

mt-ibution to the -use ra,I:a.

Iy a.aonsi uries by al.out o.1Uc torr, and the i

t:on DE is approximately 1.'. percent of the total

" soft enmponent" has !ven e-tim,ted to vary by r.d will be.iiuwed farther in the next urtion.

a!mt 0.97c ton. The morall variation is 0.:1 to i

Neutron de: Ety in the al;;.o-phere \\ aries expo.

O.45, tol". For FMrpo?s of 'ong-tenu e4timation, i

5 I

1 c

=w - a wmm>

1 k

~

t ic pattle:es, an ct :s la. IJ Sm..,..

.,. -- d_the_scrcentn:: @lj,Iltch rg The phenomenon.is,,cnown as the..rorbush de.

i2 th'e lower l'atitddes hi h,th Md:I erease, and is due to the fact tha(11ir~eErUo3 EFed byidhghetTfdisili;t@~Ts'6Tdch redizjsiJf

.ilillika'ti'et' af.~ti0dca), throngii a worldwide M.[epergy galfde rat,ittiNihimp5fichg survey, observed the cosmic ray variation at sea ti leve;. hie to the latituele errect: his results are sunnuarized in figure.a.,.ts shown in this ticure, 2.2.2. Latitude variation the ionizing enmimnent of. osmic rad,4ation varies Of the factors wh:. d.. -mtlueneexosmi.e ray.:qn:,,

by about 2 petrent throug,t.out contiguoits L,.S.

c gsilissat the earth *: surface, the(latitsde'~i6tt) latitudes, which range from :;C' to ra' N. geo.

was the tirat to be well described. Thi.s.e.@ctred magnetic. E.stensive reviews of later work have ftTr{ ft%nCti'eWh's deEMiitiTfiC which been presented by Lowder and Solon (1956),

alTrosimates a digiole located 217 miles from the linitqvi:t (10,6), and UNSCE.\\R (1000.1006).

carth's center with the poi t at 70* N. 60* W.

3foie reent work (Raft et al. 1970: Georg=.

(north aest Greenland) and IP S.,121* E. (.\\nt.

Iti;o) indiented a -light dee:va-e in cumic ray arctica ) (C NSCE.\\ R,100G : Pal.1067). W~ihi'gJ ionization commencing around # ge imacnetic

$@e.Jy_hisi5y_to_eIItTo'_il_~Iiiide}iflow en rgy] latitude (a line through Washington, D.C.. and l~]

l I

th 30 SE L315 05 57;tt C*SwC.R AY :N T ENS. !'

I

.e af $E A LEVEL (aELA!!st vaLUE$)

7 l

. N.,

s IJ l

l

.'+..

l l

i,l j

g.d. 7 I.

4 y

I i D l

3g I

l.,b[

llhb d

ll ll!

,.s 2

E!l' I

Wu iMJ i

RRwM i ifi ! i ?#*l ! :pMX..

j 1 P M (M '.j_f '..L..S

• *. ' &~../. % '

M

.% W

--. - W-e:~~~.

E 59,- h

(~'

vg', l h TR

~~ N% - *f 7

J 7

3,i

'i I IilhT

= 3 7 T '"1 i 'l i

--- Q

-.n4' Mi l- - --- -.-.- %wl

--a l 1 Q !

N l l 6)I i

~e -

w I

7.N 1 1 !I NI i 1- *G f MQ

.w

m i m==--~.,

r

"--e r

..pp< W 2N VgM

~ T~

"W' a

r i !, i i l Ti ShMVy"'IlllllIi;i l!!!]! !i!!!

T M L W i.l ll'Il l

30

[

!I I

, l 1 l l I ! l I I I I I l v

l I il i ) I i l l l e

t

' 5a

s:

53

o n

$c 3

n 9

M t'igure 3.

V.i r :Mion cf ec*mic radi.ition with ivitude O!illikan et si :976a)

T

-..~

I:

4 I

i the variation is not important. However, since Tabi. 2. sammary et sea seret ionization due to c mic radiation at l'.S. !atitudes

}

thc barometric pressure may vary by about 3 percent frem day to day,it mpments a potential t

source of error in correcting and comparing

[il,",87,'l,*.,*f 8 'f'

'"***8 ditfemnt measurements.

Hultgrist (1934) __

• 2 04 Soloa et aL c1&GG). -

2.52 2.3. Cosmic Ray Measurements E'n"#.04tifeT2besi rr- :---

M I wder and Best st366) _ -

• 10 2.18 Oh!.es e n*G96 2.0o G.*rce e.19:09 no 3: era..........=_gnita i tv oi........

2 20

, 3.1. Io m..zmg component o sries 2.se resta.svrot

~

The measurement of the ionizing component of

.:2 3,,,,,,,, :,,g,,,, _ _ _

cosmic radiation is generally exprefsed as ion Averap of patEG,alun........:

a.H pairs /em -see. (commonly expressed as -I"), and

. te,n y oc t:,2:,e. tro pr,vio,, to,,,t ati..

2 corrected to the sea-level value at 700 torr and 0* C., although not all authon mention a temper-a ature and pmssure correction. One I cormsponds to a value of 1.05 grem/hr. This ratio has been to 40 percent. Shamos and Liborf (1966), Lowder used to convert all measurements to the same and Beck (1966), and George (1970) have at-units.

tempted to explain the ditierences through ion j

Summarized in figure 5 and table 0 am meas.

chamber construction, calibration, alpha contami-l urements of the se-t-level intensity that have been nation of the measuring chamber and radon f

made by v...-ious investigarne over a period of daughters in the atmosphere (the latter two fac-4 40 years. As can be seen, there has been a enn.

tors may contribute up to 15 to 20 percent of the

-iderabic :-pread in the reported vahics, which is measured cosmic ray dose). IIomer, ditierences iemarkable even in view of the natural variations still remain, and, in view of the nmnercus cor-that have 1 cen cited. Even the mo>t meent meas.

rections which must be made to compare measure-urements ahich have been reported ditier by 30 ments at ditierent locations, it appean that the l

i i

i

=r

• t g

+

j i

3 I

i ir I

i, 1

I

.93 fB

.nsE

.tig

. M4 T8 t a4 y e. eL*: stet Figure 3.

Summary of sea-lesel ionization due to cosmic radiation 0

,_e,

ditierences will not be resolved soon. For the pur.

Table 3.

c.ainic rar neutron do equivalent at sea level pose of DE estim'ttion in the present work, a o,,,,,,a,,,,,,

Refer ****

( =*/s' >

value of 0.44 I has been assumed for the average

. s.e I

cosmic ray ionization at sea level in the United ascEn itseen.............

L l

States. This is the average of eight reported Rd' $'n'h Tf!.---- E...

• [j valacs since 1000 and is equivalent to 4.0 prem/hr.,

0,"/d'

• d,1."$'in"g"* j'*' -- ------

Os 58 or 35.3 mrem /yr. The value used in this study, S

"P*

i 35.3 mrem /yr., compares reasonably well with the g sjp += dm ra2m prem H tr uscru (ine) ad mort recent reported UNSCE.tR (1066) value of I

es mrem /yr.

this study are summarized in table 4. Based upon the adopted sea. level values and ionization pro-nie of Lowder and Beck (1066), the DE rates at 2.3.7 Neutron component altitudes up to 15,000 feet have been plotted in i

Several factors have contributed to relatively figure 6. Estimates of cosmic radiation DE at l

poorer knowledge of the netitron DE rate at sea cosmic radiation done equiraient at sea level i

Ievel as compared to the ionizing DE rate. First, Table 4.

l the neutron thtx in the atmosphere is more sen-ad mm/n.

se t

sitive to the time, latitude, and altitude variations

,.fM, "?'**

d.

80

(*

which have been described. Since the neutron DE rate has been measured over a relatitely shorter

~

g time and by fcwer investigators, the intercom-parison of diiTerent work is complicated by the creater natural v triations. In addition, incon-

• • p

~4 i

!-tencies exist in reportin:: results so that it is E

common to find data reported either in dose or

[

k DE units.

{

UNSCE.iR (1906) reviewed the neutron meas-nrements through 10G5 and, based upon a re-ported range of 0.3 to 1.1 mrad /yr.,conelnded that o.7 mradJyr. should be taken as the typical sea-7 level value at middle latitudes. The International

E 8,,,,

3

! t Commiesion on Radiological Protection (ICRP)

J (Upton.1006), in reviewing cosmic radiation j L hazards to supersonic jet passencers and crew, has

)

2

}

asu ned a sen. level value of 4.3 x 10-8. ara d, kr.

j f.

u.n:. cw:mr g

to.M mradlyr.) and a quality factor of 9. which j

cortc3 ponds to 3.0 mrem 'yr. Watt (1967) has ealculated a value of 6.3 mrem /yr. O'Brien and i

x McLaugidin (1070). in addition to reviewm.g the

]

discrepancies which presently exist in the neutron i

data. ':av > ik dated a vahie of ~0.33 mrem /yr.

L g,:. :.n,. m-i v:.. a.n..m.,;;;,q ;.ge,ri;;p..; q y,N g ga-

.i gality factor of 3 may also Le. ferred from m

i

he:. data..\\ aummary of the preceding informa-

[

t...-i,..... i. o rra -

l

".'..O.. !.*:' M...'J,'...

2 tion :s presented in table 3. For the purpose of

.irse e imation in the present stmly, the recom-l ui mi..t ons of UN6CE.\\R ( mm a; i U nua vt

.,, I t

8 2

8 3

a al. t *

• Gi.i have I cen follow ed b\\ using the s thics u.c.:,

..m:::, rur i l

..t' a.: mrad /yr. and QF = c. respe-t s e y.

The co-mie radiation dose rates to be med in rigure s. cosmic ray dose equis alent es. elevation

• 0 w

--e,,s,--

+--e w-ee-w--

---w c--y

+wm-m-,e=

,,,---,e

,--w-a--w~-

--,m

+

-m--

+ " -

9

s..

l bral Table 3. Distribution of the l'.S. population vs. elevation Nf*

di:terent elevations were made using data frrun (1964) this figure.

Ceration laterval glu' feett Popula:1oe Cumulative percent 2.4. Population Distribut,on i

o-o s 56.609 494 49.3 63.oo7. 20 53.4

' o.5-1 io1 of the L.. d States was d.is 2-2 to. 4e.oes e4 s.

~

The populat.

nite s.:n:se er.

., which.-

1:d 24 a.sas.ses 9e e tributed in 1000 as shown.in figure is 4-e.............

6-8 ~

618.ooo too:9 39 adapted from the t.S. Census Bureau (1963).

s.no 22:2Z2:

it.ooo o

14.ooo noo s yo on o

Through use of the population mstribution map T*------------

178 8:8278

.ro.

and a U.S. Geological Surrey topographic map s at (Gannett,1916), the population of the United States was found to be distributed by elevation of the nonurbanized areas. The mean elevation

in as presented in table 5. The mean populated cle-of the nonurbanized population was computed at ration of each State was computed by averaging by weighting the population in each e?evation the population of urbanized areas, for which an segment by the segment midpoint. Thus, the mean

.,g approximate elevation was available (Rand Mc-populated elevation (feet) of the nonurbanized Nally.1071; Gannett,1006), and the population area of state =

)

M.

'l 4

4 l>

e.

t l

i A-

u. ".

a

+.

..A 3

, '. 0; 4 l

s-A>*T iF.

l g.

n.v.'

f.

y?

e r em.

., '...s.}.,,

u.

~,;

T... - y

<;a.~*'.*,

< -,..,w e :.a

• ;.:, * -W[1,. **,5 'g

.t a

.t/

,,/' *

' ' '

• s;,,. 5.. z,.;

, '...'., ;.rv$;

.. ). ; *. e *.... <

s

~.. > :

_ a..:

..a

h. s '.

. ~.

y ',7.. i. '. /*'

.* 'a.B,-;,,j ~,%'

.. s

?. -

,-[ g',. u.. t.

m

,:e. My s

~};

. g'

'V c

.' M

.,.:)7

^

.[.

%. ' q ' ", :.,. '.

i

.t..

4 '.,:, e -;...,~..., -

. s.

.:..... 5. *,

...} ;;; +. 7,, -.,.] " ';.

j>

}

ja.. _ -

• y-y -

e

• ?.

s

. E-j

... ;.c

..-i

'.. V.Q.' : _W ;:s 9:,;. L'i :

J t *.,O'

? f.

. _. k

,-*.,.O,

' ;.:z-l-\\

j

- ?

3..,

q **

'Q q

ec G

?P

=

f

st ::- * :.a s *1 ::s et es:=s l

g

.+s.:t.s n ** : : assas I

.r. M-as Figure *. Popuistion distribution.1960 11

~ _

4-..r.--y.-.

,,,.._,,.,__.._.-_-._m

.m.-

1 4

No. living at rNo. livine sti

. (500 to 1,000 feet)

• _,

i r

l (0to500" feet [*,-

i l

Nonurbanized [mpulation of State Three exceptions to this procedure wen re-have been used in conjunction with values ob.

j quired. Fint, the icimlation of IIawaii was as.

tained from figure 6 in order to cetimate the sumed to be distributed 95 percent in the 0 to cosmic ray DE in the United States, and this wo-foot interval and 5 percent in the 500 to information is sununaried in figure d. As can be 1.v00-foot interval. since the scale of the U.S.

seen, the DE is relatively uniform in the eastern Census Bureau map did not justify a emuparieon half of the country but increases in areas of with topographie data. Secondly, several bw-higher elevation in the west. Th.' populations of j

lying States on the Atlantic and Gulf Coa-ts have Alaska and IIawaii. which ar, r.ct -hown, wem mean clavations less than 250 feet ba.ed on geog-also calculated as receiving between 40 and 5b

{

raphy alone. In these States, which are Delaware, mrem /yr.

. t Florida. Louisiana. and Rhode Island, Gannett's It is interesting to note that.a small ates

{

(1594) entimates of mean elevations were used on the east side of the Rocky Mountains, in the (Go,100,100. 200 feet, res1wtively) for the non-vicinity of Leadville, Colorado, includes all of the g

urbanized potmlation. Thirdly, it berome:r neces-populated communities in the United States I

sary later in this report to divide certain States which are at elevations grener than M.000 feet, j

into Coastal Plain and non. Coastal Plain regions.

These conummities are betreen 10.000 and 10,500 y

The Coastal P!ain regions (to be specified later) feet: this elevation corresponds to a cosmic ray are also low-lying areas and have been as-igne l DE of 100 mrem /yr., or approximately four times I

mean elevations based on a cumparim of popu-the sea-level DE. Additional calculations are lation distribution and topographic data for the presented in chapter 4, where the contribution 5

respo tive regions.

from terrestrial and other sources will a!so be T' e estin arcs of mean populated elevations disca. sed.

og

' Qui 5, q

MMA =r,

,A.

.P O 6\\p h,

.m y :.:, n o[

9 - @g,n + y--.:

i t he

<1 t

e g

c I

l n $ -~-,

f-}$j' w

{

,__. A

~^

-l Grh w,f) 4 t

4..g,' Y.:..r$Q%

o t

=

,m nd5s* & ll_ l fry b, i

x ;~

,~ - x?

w en

% 3-NM

- " " ~

~

b J's -/

g=("%.gvDv

.~cn[.N i

-[

s a i

m M' h ('

c [l

__~_a

}

-rm? q W"%% \\

3:g gN

'. i' i

i i

(

i rigure 9.

Dee equis atent from cosmic radiation (mrem /yr.)

i 12 j

\\._..

t 1-I I

i i

s I

t F

ob-the this I

i be i

CHAPTER 3. TERRESTRIAL RADIATION EXPOSURE of i of In the preceding chapter, the factors which tritium are two well-known examples of this m

30 adect exposure to cosmic radiation have been process; however, the DE due to cosmic ray-discussed. In this chapter, the same approach will induced nuclides is insignificant.

be taken to discuss man's exposure to natural ter-Potassium 40 occurs as one of three potassium

,3 he ie topes. The two most abundant isoto.:es, potas-restrial sources of radiation.

n sium-30 (03.1 percent) and potassium 41 (6.9

,e percent), are stable, whemas potasshu. 4 0 (0.0119 2s 3.1. Sources percent) decays with a half life y 1.25 x 10' e:

m years. A 1.46 MeV gamma ray is emitted in 11 Naturally occurring radiomtelides contribute percent of the disintegrations. and this gamma 17 signifiemtly to man's external exporun. In most ray is the source of terre-trial DE from the s

e of the United States, the magnitude of terrestrial nuclide.

W radiation exposure is relatively uniform and is Thorium 232 and uranium-235 decay chains in n and Cb. Uranium-235 is similar to that due to cosmic radiation. As far as are shown in tables a

is known there are no' terre-trial areas in the the parent element of a third decay chain: how-United States which yield DE rates comparable ever, as can be seen from table 7, the energy re-to the high radiation levels 10 to 100 times greater leared from radioactise decay from this chain than normal") which have been ob erved in is insignificant in comparison to the uranium-23S and thorium-202 chains. Although the nuclide other parts of the world, notably a few impu-lared areas of Umzil and India (UNSCEAR.

composition of the rock in table 7 diders slightly from estimates which will be presented later, it 1962).

The nuelides which contribute to man's nathral is clear that uranium 235, thorium-232, and expcsum have been extensively wriewed elee-potassium-40 may be assmaed to account for where (Lowder and Solon.105G; UNSCEAR, practically all of man's terrestrial radiation 1002). From the standpoint of man's exposure, exposure.

only potassium 40 and the radioactive decay As in the case of cosmic radiation. tertestrial sources have been -tudied primarily for purposes chains of uranium 205 and thorium-232 are other than intere>t in population expomre to significant. In aihiition to the-e nuclides, Lowder and Solon (10.%) summarized physteal data for background radiation. For examp!c. measure-21 nue!! des which exist or are hypothesized to ments made early in this tentury were concerned exist; however, long halfdives and low abun-with geologie dating.md heat generation due to dances acconut for their insignitienut DE to man.

radioattive decay. Since the 1040's, however, most n e ; :::- e of et:

rar remrons mmres that of the literature concerning uranium and thorium capture reactions da occur in roil at the earthN

!.as twmted from an ecanomie intete-t la ihe ao surface and in 'he atmosphere. thtlA te-idting in elements. WitI15H !!.e p:Ist 15 vC:trs. add!! Ion:tI the probabIe occurrence of Inany additional radio-data h:gre I een lepo!!ed ultich.viate ditWtly to active nuclides. The prodtiction of carbon 14 and man's expo-ure to terretria! 3.uirecs.

13 w-

1 I

Table Ga-1*ranium-238 decay chain -uranium series (la + 2)*

(Courtesy Radiological Health Handbook. Revised January 1970) i e

e Major radiattaa emers,te,s (MeV)

M 6 st erta an

,,,g,,,,,,,g.

bellee

,,,g g,t i g, nous e

l 3

8lju Ursete t

6. 51a lc'y 6.13 (23Q e.20 (73V sj*Th trastus I 26.14 0.103

( 21*J 0.06he (3.51) s 0.193 094 0.09k (41) l i

i e

s;;,,=

trentas I, 1.17e 2.29 (let) 0.765 (0.1ct) 1.001 (0.60%)

e4 5 -= l 3gn g

I h

+

llp.

trantwa Z

6. 7 3h 0.33 (64V 0.100 (501)

^

1.13 (1313 0.70 (2 0

[

I 0.90 (7013 j

8ljtf Ursanum 11 2..?a 10sy

6. *2 (212 0.033

10. 2%)

4

. 77 (72V

}

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r,t?g N rios 3 St aate im, i =.. r a. .... -r c c '.-- esser e tu s..rie s..aere. t s.a t e t ese r. s,,s. e : -a s. ..s '. o *. 4 s.. st,, e u,e a t,,atue.t se i f. *ee u a r t s.-e t r.r as e r ..r,.. ., e e, - - r.,- e s s. 2 .r s., -un...c tnet;:.ters. s..- r - u .e.. a. i s -...re.. r...L..s .a se r. ent s er o erste, =r.... re r. s.a. t.. r.. e -, .-n es. w * :re 13-c o e= a so... .r m < i e r. e. c. g.. *.- t '. ser, 1. *.. .e.

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e r s. a t - u to r s. w.. . ae-n. =.:ay 4 ie. r t eleaud '3y 1 ;rsm of rock Gent ry et, al. (10">9) atul Grahn and Kratch-n.4e - 'ithe-phere) Kegan et al. (1971) inan (1063), in int e.-tig.ttiotts of fetal malfortua. tion e-tin"'ed popul.ttion expomre flom.lat:t i d%S$oa. NINI ou l'a al geolmay aml uranium tuertes but made no measurements. Se; rill (1063) conducted 2 later ri runt - c x t + l . re study concerned uith !walth edetts of back::ro'md i,,...a.rr. nal.. ~.- }{3g 3-a, gg .g g g. c a., .]I.g g egg g. .a is

• • d.

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• ggj
• T $ l.........-.

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~ i about this time, portable multichannel gamma-U.S. population lives almost entirely over rocks ray spectrometers were developed. and these of sedimentary origin. instruments allowed field determinations of l the amounts of potassium-40, uranium-20S, and thorium 2?,2 present in the soil. Data reported br Table s. Typu er wreck in the contiguous Beck et al. (1964a,1964b,1000a) are representE-Un w states I tive of this technique. p,,,,nt et I Estersive literature reviews exist concerning " *8" P" " T* '"42"' I the distribution and abundance of the naturally outerurr a.s 9 1*pper Terttary 13.s occurring radloartive elements in the earth.s crust Lw er Tertiarr 96 i (.idams et al., W50: Peterman.1963: Clark et al E C E ;c nw

• d seemac.cr ss 2 106G: Finch.1067; Overstreet.1967: Wedepohl, fM78,'j,"l,'"*

2U IN9). The purpose of the following text is not h*"Je!O%,tu ; O; r to duplicate this information, but rather to pre- "J3 ' "' i' P"' '

• 6*
• u sent sudicient data from these sources to permit OyglL"T "'

vmua_.g3,u, an understanding of variations which exist in b;"Tr l'lk/'"* taun.tre-a rseon

.s measurements of background radiation.

To t. loo.o The earth's ernst is composed of igneous, meta. morphie, and sedimentary rocks; the first two j classifications account for approximately 90 per-Table o presents the average amounts of ura. eent of the mass of the crust. Sedimentary <cks nium ' lorium.and potassium-40 in common rocks. accumulate at the top of the crust, however and soil. and the earth'. upper crust. It can be <ce. thus Jackson (1964) estimates that sedimentary from the crustal average that potas-lum.40 mu rocks emer atent 75 percent of the earth's land the thorium-2P,2 decay chain ca. h contribute ap-proximately 40 percent of the dose rate at three a rea. Based on an analysis of the geology msp. U.S. feet above the grotmd.and the uranium.2:M de-ny Geological Survey (1971) sedimentary rocks chain contributes approximately da percent of the cover approximately 55 percent of the contiguou< total. The uranium-203 decay chain includes the U.S. Innd area, and are distributed by geologie gas radon-222, which can di: fuse through the -oil age as shown in t.:ble S. Sedimentary rocks may and into the atmosphere. The ditrusion reduces the Le classified as shale, sandstone, or limestone. equilibrium concentration of raden-222 daughters j which have a relative abundance in the ratio of in the soil, thereby reducing the DE contribution 3:1:1. Since the metamorphic and igneous rocks from the uranium-20S series by as much as 50 of table 5 are concentrated in sparsely inhabited I v ent . eck and de P!anque. IMS). The mountainous areas. it can he assumed that the th0 inm-202 decay chain also includes a gis. r l l Table 9. Radionuclide cont.nt and dose equivalent rates from common rocks and soil i Urs:!um

• torium us =*ui m-48 Teal

.tse k pt m imrem/yra * .pm j in.tr9t/yrd *

pt nr.re r./yrd

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• c*a rk et.1.

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116t!4 ). 'G 7 '~... _ n .--n-- ,w n,'~ -w -,, -, ~,., -,,,,, e.,v-.-y,y.,,-,,-,,,,..,~,ww-, n.

t t t acks i radon 220; wever, the short half-life of ndon-measurements an slightly less than for the upper ( e20 (54.5 sec.) prevents a significant loss of gas cru-t. This is as expected,-ince the turficial data (and daughter products) to the atmosphere. are based upon in altu spectrometrie measure-f In addition to the gamma rays from terrestrial. ments and refleet the factors which have already l sources, which are the basis for the DE values ken di-cueed. Mixing and weathering proiws I in table D, alpha and beta particle emissions also at the + oil /mmosphere interface sette to reduce ?-- l eccur. The alpha particles may le asumed to le the amount of variation that one would expect i absorbed in the soil, and it is generally assumed haaed uten bedrock analyses. Lowder and Om. I that the beta mys may also be negiceted. Berk don (1965) for example. found that ahhough u et al. (1000a) have completed the most recen: 1.edrock radioactivity and above. ground DE f and thorough study of terrest rial beta. ray rates could be correlated, the DE rate above wurces. In measurements conducted 40 to 150 cm ground inemased only slightly for a several. fold above the ground surface. they found beta rays increase in l'edrock radioactivity. I were attenuated with a half thickness of 150 l mg/cm..it one meter above the grmmd. gamma 3.,. T.ariations m Terrestrial Radiat. ion 2 i rays and cosmic rays produced _..mn patr/cm,. l I see.(I) in air and beta rays prmluced 13 I..il- .\\s one might expect from section 3.1, the pri. though these authors concluded that the gonadi mary determinant of the terrestrial radiation i [a-and bone marrow received a small and negligib!e level in a given Icention is the soil concentration I)E from beta rays, it is conceisable that this of natural radionuclides. IIowever, the radiation 4 + source could present a significant expo-ure for level above the ground will vary because of the persons in special circumstances, e.g., individuals loewnee of soil moisture and the amount of radon a who live on earthen floors. In summary. present daughters present in the atmosphere. The two fac-evidence suggests that the beta. ray DE due to tors are related but will be discussed separately. terrestrial sources may be neghcred: how ever. The resultir.; variations in terrestrial radia-extensive supporting evidence is lackine. tion expo +ure will be cyclical and can markedly Table D is imended to pre-ent a general idea of adect the oh-ervations from day to day..is with 1 the DE rate from various rocks. but practical the variations in cosmic radiation. an underrrand. d I 'e l limitations prevent the use of the-e data for c-ti. ing of the sources of variation in terre.-trial ' matine population exposure. I hair and Gottfried -aurces is helpful N explaining diderences in 75 'n (1064) have outlined some of the pitfalls in esti-reported umuremen

• 30 matine average elemental contems of various rocks. For exmuple. they reconanend that, the 3.2.1. Radon daughter products

~ a Radon.222. T : = 0.5 days. occurs in the ura-number of analyses of a rock type should be pro. i portional to the abundance of the rock in natura. nium.005 decay chain, and radon.220. T : = M.5 In practice. however, mre rocks tend to be over-tec., in the thorium-200 decay chain. Because of analyzed in relation to the conmmu types and the shorter half-life of radon-220, there is less thereby contribute a disproporthinate -hare to opportunity for didusion from the ground, and the overall mean. In addition. surtleial events, thus airlmne concentrations of rmiondM aty .-,ch as misine of rncks with ore mic tratter. generally two orders of magnitude greater than glaciation, and the -imultaneous oc..rrence of those of radon.229 (Gold et al 1064). m eral rock types, make popuhnion espo-un. Under umst condiths mdon daneh*cu in the [rotn 3 3 ingle rock type or rock derig alite un-atmO-phere contribute a few tenths of a,tdym br. ~ likely. For these reasone, elemental.ordy -es of to the DE rate r Beck et al.. mcibt lav barn. roh are not adequate for makine e-rin.:.tv of metrie 1.munn. atu-pheric ten teat ure bn et. pop'da!Mn espo m e. I" f 1re lwh[ul in 'luder-holt. Iitt!e wind. tnd !ow snil mr iffure Ie.u t in f e 3tandine s ariations.mich esist in D E rate

acrea-ed raden emanarkn from the grand nd mea-mvment s.

high air an entrations of radon dan; hiers H Ml ' r surticial et ah, 1964: Kraner et aL mm Gold et al. Table 9 -Lows that the av(rage < i 17

(1064), in a 5-year study of atmospherie radon 13 uniow eit omtunc atarroam _ levels, reported an average radon 222 concentra-3.2 [ tion of 0.26 pCi/ liter, with maximum concentra-3,3 l " [

• y,','1"[,',".*3 tions (0.S pCi/ Iter) occurring during the fall u

^'T'Tuo t 2 ' T -- a m t :s. n. m e - months. These concentrations correspond to 0.4 23 g l and 1.3 prem/hr., assuming the conversion factor of Hultqvist (1956).* In developing this factor, y g 2.s Hultqvist assumed the radon 222 was in equilib-2.7 '( f I rium with its daughters. ::n fact, however, the u daughter concentrations are generally 50 to 100 u 6 121s 6 121s 6121 6 121s 6121s percent of the values that could be estimated from the radon-222 concentration (Gold et at, APRIL 23 APRIL 24 APRIL 23 april 26 APRIL 27 1064; Harley,1953), so that a value of 0.3 prem/ Figure 9. Ionization n. date and local time (PST) on hr. is probably a reasonable estimate of the aver. f*h*** d'illint P atforra coe Huntington Beach, l age (xternal DE due to radon daughten. This C'E N' '8 # estimate is supported by the spectrometric mens-urements by Beck et al. (1066a), who reported gamma DE rates at several locations to be be-the average is about 0.3 grem/hr. Under these tween 0.1 to 0.5 prem/hr. due to radon daughters. circumstances, the contribution of radon daugh-There are other reports of outdoor radon levels ters to the total terrestrial plus cosmic DE rate averaging 10 percent of the estimate cited here at most locations will be less than 10 percent, and (see Lowder and Solon,1956; and Haltqvist, usually kss than 5 percent of the total. 1956), but the astimate bv Gold et al. (1964) is 3.2.2. Moisture and snow cover assumed to be are correct because of the longer period of observation. It has already been menticned that soil mois-George (1970) has provided what may be an ture retards the ditTusion of raden into the example of" a relatively high DE rate due to atmosphere and thus nduces exposure to the radon and its daughters. In an edort to isolate airborne daughter products; in mest soils, the his cosmic ray detection instruments from terres-amount of water varies from 5 to 25 percent on j trial sources,he moved to an osshore drilling plat-a weight basis (Jackson,1064). Beck et al. I form 3.6 bn west of Los Ange!es. By so doing, (1966a) found that the potassium-40 DE rate he was able to observe increases in the ionization decreases bv about 30 percent when the soil water i ~ l which coincided with the odshore winds (fig-content inereases from 0 to 30 percent, becauso ure 9). The diference in high and Iow readings of the increased shieldine provided bv the water; ~ was approximately 0.6 ion pairs /cm'.see., or 1.0 however, soil moisture acts in two conflicting prem/hr. Since the usual temperature inversion of wars on the terrestrial DE rate. The first has al-the Los Angeles basin results in little vertical ready been mentioned, e.g., the gamma-ray at-mixing, this value is probably close to the upper tenuation of the natural emitters. Conflicting with limit of the external DE from radon and its this is the reduced radon migration to the surface l 3 l daughten. It should be noted that radon levels and accumulation of radon daughters in the over oceans are approximately one one-htmdredth ground. The daughters of radon account for more of land values (IIcss and Parkinson,1953), and than 95 percent of the gamma ray energy from thus there was probably an insignificant radon the uranium-235 series (Kogan et al.,1971), so j mntribution from tl.e ocean to the measurement. that their presence in the ground increases the The probable range of axternal DE due to expomre from this series. The net erfect is for rmlen daughters, therefore,is 0 to 1 grem/hr., and soil moisture to decrease the petassium-40 and thorium-232 rates and to increase or lease un-i changed the uranium-20S series DE rate 1 Beck ' ten pairs < cm%ee. = OM X raden._C cancentration et al.,,0663). 4 IC Mter; 1 kn rair im%c. =- 1.C, rem /hr. f i IS ~

I ~ In a comparison of spectrometeric measure-weather when personnel and equipment stress is ments obtained in Denver, Beck et al. (1066a) at a minimum, and therefore the measurersents y-l observed that the measurements obtained in dry may not retlect the seasonal variations of back-J,. years (1962 and 1063) were 15 to 25 percent less ground due to ground moisture and snox cover. than in a wet year (1965). This indicates that It is possible, howertr. to estimate the impor- < r. _ the gamma ray attenuation by the soil water was tance of snow cover on long. term exposure from ~ more than otiset by accompanying son retention the data of Magi et al. (1970). Based on summer of radon daughter products. Therefore, one measurements alone, they estimated the yearly would expect variations of this magnitude DE from natural radiation to be 78 mrem /yr. g-9 throughout the country where periodic drought at Idre, Sweden, whereas year-round measure-and rainy periods occur. Once again, this empha-ments resulted in a 10 percent lower estimate,70 s sizes the ditliculty in interpreting spot measure-mrem /yr. They attributed this ditierence to the w ' U ments and using such measuttments for long. term attenuation of terrestrial sources by snow cover. The average enow cover at this location is 15 exposure estimates. The etreet of snow cover on the dose rate inches and persists for approximately 150 days / A from terrestrial sources was calculated by Sievert yr. (Pershagen,1960). Natural mdiation meas-and Hultqvist (1050) (figure 10). The calculated urements in three other Swedish citics, located in values agree well with measurements reported regions. of less snowfall, showed no variation in the same reference and with more recent from ummer to winter.

e i-measurements by Magi et al. (1970). Concur-Although the etfect of snow cover on measure-rently obtained snow cover and background ments can be substantial, the overall intluence on e

d radiation ineasurements are virtually nonexist-population exposure is asumed to be negligible ent. This fact illustrates a bias which might in the United States. In most populated areas, exist in practically all measurements of back-there is relatively little snowfall, and it does not ground radiation. They are obtained in fair rcmain for long periods of time. In addition to these factors, the pmpensity for indoor urban living, and rapid removal of snm, in most popu-s.

3 lated areas in the United States, tend to reduce s the significance of snow buildup as an attenuator 3 of terrestrial gamma sources. In addition to the variation. in the source term [ (ter-estrial gamma.rav sources), there are also o a h g 80 other factors which att'ect the < xposure of man to 2 j natural radiation. Examples of such factora ate =

1. = 0*10 man's choice of home-elevation, geology. and 2

building material. In addition, shielding provided c 50 [ } 7 by the body attenuates the dose to internal or-l 5 gans. These factors will be dis:ussed in chapter 4. 5_. 20 p = 0.25 i 3.3. Measurements u. o

1. = 0.40 g20 3.3.1. Ground surveys

( A summary of ground surveys of natural ter-b0 3 0 20 40 60 30 100 restrial radiation in the United States is pre-CEPTH OF $NCW IN cm seated in table 10. Lowder and Solon (ING) re-viewed -ercral isolated backcmund measurements i & e se Fi;ure 10. Dvercase in gamma r.diation 3 th depth M *- Nh i of snoa emr at three ditTerent denstties (:wsert and measurements have 1 cen reported s.mee 1%6. The IIultqvist.1952) 10 I t .--.,..,--,-_-.e,, a a -, .,--m p._

Table 10. Ground surveys of background radiation la the t*aited States l Instrumentation Yalue (arem/yrd Remarte Itefe.cace ' beattoa 6 5 los.106C 33 t'.S. towns and tea chamber

• 73-197 133 meesorementa cttles Stephens et at, 30 ti. cations nese Portable sciatura-
• 33-104 It'el San Frametsee ter Beck et al 1DC4a.

art.rna. 210 loca. Spwtremeter and 4-150 h-3 raenscrements/tocation, some takes 1;MI4h,11666a. tions to 23 S:stes ton chan. bee (From 1064h to dttervat yeare ref. ) Scall and Reed. New ttsmpshire. Personal doetme-

• 113-It1 400 people: performed concurrently ItH'6D with beder and Condos (13f 3) 1964 Vermont ters tion tham-bers t Lwder and Cendon.

New nampshire. Speetrometer 45-95 Outdoors 1263 Vermont 1%rtable *clattila-U.7 x cutloor Indoors-160 horses and apartments ter enlues l tToltenberg et al 30 locations near Portable scio 1Ma-

• 33-102 1s69 Saa Franet ce ter
  • ame as

$te-phens et al, 1361) } Letn et al 1965 1100 to,res la 24 Portable setat!Ua-

• 33-118 3001 aessarements : all States were States ter east of the '.!:ssts.tppi Rtrer etcept ton a, Sunnesota, and 4.%rado Golden. J 1968 Fiortda-etetntte of Portable,ctattila.
• 39-115 1.161 measurements, me "trity la south-western Polk Countr phosphate beds for Testes et at 1070 Boston. Stase.

fon chamber

• 53-121 4 measur-ments out'foor.
• *il-105 13 taca*urements/6 frame dwentage
• 41-114

't measureenents/3 arte.

• 73-118 16 measurements /4 otSce blogs.

ID Men et al.. f,. Nrmore. Ositf Thermehemines-

• 32-73 Au frame homes eacept 4 1:*i1 Inside 110 homes cent d.Mme*ers

.I

• Value, trwtude treron e to terrestrial and co,mic rsJ1stloa. those act factnoted. the <alues are terrestrial component cals.

I authors cited in table 10 hace frequently re-distributed according to population density-ported their re-ults in more than one article: an Iw;e cities hasing the most measurements and { - ttempt has been made to cite the taost compre-t ural areas having the least. The data in table 10 hen 31se reference for each se: of measurements. generally do not satisfy this criterion, but in fair-I The usefidneu of the sarious measurements in ness to the investiguors it thould he noted that table 10 for e-timating population exposure varies no one had as his primary goal the estimation of con >iderably, and the reported measurements will population exposme for the entire United States. he useti to ilhi<trate sescrallimitations on making The mea 3urements by Beck et al. (1064ab, e such estimates. Ideally, an cutimate of exposum 1966ab), Solon (m60), Stephens et al. (1061), i to people rhuuld rely ulum measurements as close and Woller.oerg et al. (1060) re>ulted from an l as mssihte to the receptor. i.e., personal dosime,- initial intenst in the impact of nuclear weapons i ters. The mea-urement of background radiation fallout on man's radiation expcsure. In contrast strains the detection capability of mo t dosime-to this, the data of Iavder and Condon (IN5) s ters, however. and this di: lieu!ty is einupounded and Yeates et al. (1970) were obtained because j hy the expo-ure which is received by the dosime-of the authors' interest in natural background l ter uhile it is nur being worn-at night or en radiation. These latter data are useful in estimat-innte fnim u-er to reader. Therefore, unle-s rela-ing population exposure,but only for a relatively risel,v -mail diferences of expo-ure in a popuhu small proportion of the tctal U.S. population. ion are being -tudied and :.:ood control mer the The t hoice of inetrmnentation in e.uvironmental r i i experhnent exi.-ts, as in an ephlemiological study surseys of background radiation has aleo influ-l i Segall ami !!eed.1964), it is shupler and per-enced the utility of the data. As one would ex-ha;v more accurate to take emiroutnental meas-put, the most comprehensive data wouhl be f m emo :- an.1 e-mtc pepulation i xpo-ure. olcained by using tuore than one instrmuent at l In onier for ;opulation expo-are e-timates to each men-urement -ite. This teihuique :s mnd I*

aile fl eut els) i rOI.lut ra al Leellt eNe'If *. iI pill *Wk I87 tbf daIa of b C E eI A! !

would be -irable f. .nea-urements :o be WCCab). who genern!!y obtained spectral data i n_

ll ' ' ,:v~ ~,- i o

s 7

/ ~, N 1-a / t Table 11. Dow equivalent masoreraents is M States, p '/ e and an ion chamber reading at each location.

• dapted frosa 1.evia et aL (1968) {

l ~ The spectral data were especially important for 3,,,,,, l j, interpreting measuttments obtained in the first state mnwr. uc. ro m. an./re. ( half of the 1060's, when work by Beck et at was caloria.... reo n n-accomplished. In additica to allowing for an 2.354 24 64 >!!chtgst u4 se n estunation of the contribut:en of potassium-40, N*a'fa?."*..:n

• i!

io manewt.

horium 232, and uranium-235 to the total terres-59 r39 33 c.orida......

Fl an et 6e / W IS"*l.. ::: U N N' trial DE, the contribution of nuclear weapons orc fallout to the total DE could be estimated with!!EU.. :: Si E O the spectrometer data. The sienificance of fallout I.!UdinW: di _N will be discussed later in this section. , ',?2 e North carottes. / 2n 67 i -o;, is U Ele'n ~ ,, }ni U "W Several investicators have u<ed pottable se.m. x r na m.htm. / tilhtion detectoE for measuring natural back- $I,Hiisi" A d E' ,, ~ ground. These small, hand held instruments allow D'l $*M4: 20 N ~,e 2-the user to make several measurements in the tirae it would take to obtain ion chamber and IO"n'l'". :: U U "1

• • • • • ~2--

spectrum measurements at one location. Unfor-

• * * ' =

/ tunately sodium iodide (NaI) detectors, the scin-tillating medium, ao not detect cosmic radiation _, pga,=g, ,, s,, y,,,,,,,,, j 2fa r==. cda 2:8 mee=/rr.j ^ as uiiciently.as gamma mdiation. In using a 3. - /- / by 5. inch detector with a high energy cutod of can be seen from table >11, the means vary by as 3.1 MeV, Beck et al. (1964b) found that the sea. much as a facter of two--from 6JG grem/hr. (59 ~ level cosmic ray contribution to the energy spec, mrem /yr.) in Florida to 13.32 prem/hr. (117 trum was equivalent to a gamma. ray DE of 0.2 mrem /yr.) in Cdarado. l grem/hr. Instead of the expected value of approx. The response to cosmic rays of the detector j imately 3J 3 rem /hr. In a similar study using used by Levin et al. (1965) is unknown. Since i i several energy bands with a 4-by 4-inch detector, these authors tiported thn frcquent intercom-Beck et al. 000Ga) oiserved a gamma. ray re. parisons of measurements with an ion chamber sponse of less than 0.5 grem/hr. up to 0,000 feet. (see Kastner et al.,1063) were made in the field, This figure is based on the response of sereni it is likely that the tvported values are repre-I enercy bands of less than 3.4 MeV, but it is also sentative of the terrestrial, fallout, and cosmic indic'ative of the lack of detector response to cos. radiation. Levin's observation was that "the read-mic ravs..\\nother limitation on the use of port. ing= were within 4 percent of the ionization able 55ntilLtors is the strone directional depend. chamber readings 05 percent of the time." enee of the detector (see Ohlln. IND). IImres er. this !!mitation can be overcome by maintainine 3.3.2. Dese equivalent rate due to fallout the same detector orientation htring calibration The presence of fission products on the ground and measurements. from nuclear weapons testing complicates the j Notwith-tanding the limitations which have interpretation of terrestrial DE rate measure-in been discussed, it seems desirable to report ments obtained during the late 19Fs and the more deuil the.emtillometer measuremer.ts, by early and middle 100's. Unless spectrometric Levin et al. 00@. since they giratly outnumber measurements are made, the DE contribution all other U.S. measurements combined. Levin does from fallout cannot be accurately assessed. This repiut the m erages for the states in which could be a source of varying error, since fallout not mec-m ements w ere obtained. + ten-ibly becan.-e contribmed a DE of a raagnitude similar to that of the fut that meuured snes were not neces- [rotn terrNtrh] cour,'c3 in 1%3 to 1%3, wheggas Mri}y repre-= r tatit e o[ the et: tire $ tate. I[uw-measurenents show the DE rate more recent eser. he as crages bas e been computed from his from fallout to be approximately 5 to 15 percent reperted data and are prc+ented in table 11..ls 21

• m

i g

I of'the natural terrestrial DE rate (McLaughlin, ciently detailed to justify making more than one 1970). estimate of the DE rate contributed by fallout An estimate of the external DE rate due to at a given time in the Unhed States.f. fallout is presented in"rigure 11. The figure is Fa!!out measurements by Beck (196Ca) sug-basettupon'estiraates and measurements in the gest more uniformity in fallout DE ratas aeross United States; the twisolid lines define a range the United States than would be expected from in which most measu:emer.ts wou d be expected rainfall patterns. For example, measurements in l to fall, and' the dashed linef represe sts the best relatively " dry' States (Wyoming, Nevada, estimate for making a f llout correction to non-Utah) varied between 0.6 to 1.5 premf hr. in 1965, /. spectromet'rie dose nsasurements. ~ and at apprcximately the same tinye measure-ments in " wet' States,(Louisiana, South Caro-7 _[' lina, North Carolina) varied between 0.7 and 1.3 '/ d prem/hr. IIowever, too few measurements are 'l !I </ 3 reported to allow a conchision as to how the ~JF i fallout DE rate varied across the cotmtry. c _ } Three different procedures were used in de-f veloping figure 11. These are as follows: j fj l 1958 to 1962: The range of vahtes was obtained t ip 7 j \\ from CNSCHR (1964), figure 32. The corree-I \\ tion values are 34 percent of the maximum vah:e. I I p\\ This correction is based on a composite of 67 i e ~ measurements in the United States between 10G2 I f I g ? I \\ to 1965 (Beck et al.,1964a.106Ca). t g \\ 1002 to 1065: The range of. values and the I J \\ j averages are based on the same measurements by g :{ s i N i Beck et al. (1064a 10cca). 2 e$ M N ---- 1066 to present: The 1905 values of Beck et al. 5 i' 0 (1966a) show that 25 percent of the fallout dose f it ;i II k \\.E 1 rate was due to ruthenium.106 and manganese.54 L a \\_S j and 75 percent was due to cesium.137. The post-( M45' 1965 values are based on the assumption that the --ly[;b,i 25 percent portion decayed with the half-life of L 1 year and the 75 percent pertion decayed with s / half-life of 23 years. The resulting range of values is consistent with fallout meamremer.ts l in the northern !.emisphere (CNSCEAR.1966), in San Francisco (Wol'enberg et al., ;000), nnd 'ta in the eastern United States (mci 4ughlin.1970) Figure 11. Dese equivalent rate due to falt ut in the during this t:me. dome fresh fission products have o l'nited States. t95S-!91 been athled.un tb.:s mierras as a rt%,I of v.* re rien and Chinese wegons tests. but : heir comribution the total is negligible. For purposes of making corrections, it would be de<irable to know the local and countrywide

1. 13.Aen.

m eys variati, as in fallout dose r:ee. It has been shown, for eumMe. that variations in fallout deposition fhe U.S. At+nic Energy C.ur.mie-ion has spon-are cheiy related to pruipita*!on and, as a re-ed nationwMe acM -my M r o%u My .-ult. wet a reas (i.e.. areas of hiener preci o.ation) in the 4 :a4 sf.;.h ' Cili a D n N t recch e more fallout than dry areas (Straub et al., to RC. Aerial Radiological Mc -urement Sur-1000. Unfottunately, existing data are not su:!i-seys ( ARMS) were conducted (by the U.S. 22 \\,_

/ the.tRMS data would le potentially useful for Geological Survey and E. GAG., Inc.) over sp-pros'imately 25 stras which are shown in figure making esposure c5timates. 12.1 fevr additional areas have been suneyed Details of the purpose and promhuts of the ?., but are not inelnded in this analysis because of .\\RMS surveys are presented in the reports listed their relatively small size and spne population. in table 12 (or see Guillou, im); however, s In the coune of reviewing stailable sm.rees brief description is pitsented here in order to of information en natural r.sdiation sources, it introduce the measurements. The standard.41018 was found that none of the published.\\RMb inta survey covered an ares of 10,000 squart mi?es [ had been used for estimating population expo-encompassing r. nue! ear facility, although there sure..\\s a. nt step in detennining if the data is some variation irt areas covered detedin t on i would be useful for this purpose, the population the site location in tilation to mountains rad l of each survey area (table 12) was estimated oceans. The surveys were intended to provide in. formatica on radiation levels in the vicinity of from U.S. Census Bureau Map G.E. 50, No.1, nuclev installations so that futme releans of ."] J 1963. It was found that approximately 30 percent of ihe U.S. population (1060 census) resided in radioactive material to the environment from the the survey arer. and thus it was concluded that facilities could be detected. This naturally raises ~, e. a 1 r.- b s. i g s.._ /_ s ~ A., fq,$#A ;'

• ~'"=n/ C r t.,

? -i

• F1 w

4. -G y-;. i s n ? w ) b_1 ' f f ., I ' ' l lh TZ.s.s&g$5& a. \\ 4 ~ g .i lV: e Q s :- ~$&f- ~*. w, n, t = ac<, M.5 W F.4Ts [r.M!@~ u it d s ~ 7D.V.== km mpi / f \\ l E >=:.ra. q %. 'A !$.s 4^ N,...e)'"'/m _ g3 war.A s s..:..t... s i c u m.s, s% 5'''' es m-s P1 : =E g\\\\ d J I l \\ K ~ m c :v.us:: h i P m,s \\ q v.a I i O *"s :.u.5 :s:tc0::4' s'm er ta ms sm c i Figure 12..\\eris1 radiological measuring surveys TI I e eieniis

5 I l i s i Table 12. Population la AR.4fS seems Poestatten Refereen Aree iSgure 10) t eet.19407 922.*S4 oea. fre. Tees. 130.600 g Bates (1982)................................... Ide.e e*aus.14ste (NATS) Bates (13stal................................ s.6*3.023 Ptrestergt. *e. " 106.344 !tates t196Ce)............................. Columese. Gate 4.766.791 Bates t1D M t)............................... Los angeles. Callt. 4.364.993 i !bcas etW 2p................................ see Traartsee, Caaf. Beeks t19665.................................... 4.S $1.320 i Chicego. Ill 4.T 41.294 I Ta at ead PttkIa i1370).................,,........ esmdea. N J..Pht:adelrhia. Pa. 1.006.690 G u i11oe i I M3a p......................... Norfait. Ya. 1.309.198 Gall 30s t19G3D)................................ Galecetes, res. 1*9.427 G u u l ee t 1M3e p.................................. Las recas. Nee. 202.740 i Gu!Hes et aL (1963)........................... Santa Itarbers. Cant. ( Arguelle) 602.601 Catuou e1945)................................... Psrr S

40.99s ora-4 C.. ria.

1Ma 3............................... G ut!Io.e a s.I*1.919 a u tu e i 1 M a n i................................ C1Pfl Saft. ohle 361.218 Cus11.se t1M0cl................................ AL duerque. N.Stes. 1.456.128 GtitMee 4196 M t............+..................... Atlaara. Ga. edNLp l M ac K s a ar a l M2 n................................ Cne.nie.Carlsbad. N Stes. 110.000 Star K siler 1M3)............................ W4,hington. D C. t Ft 3eivotrl 3 ???.371 } 2.027.148 i Neuchet e twi6 t ...........s...................... ?ttaneapons. Stina, iE h R! sert 2.0 2978 %*euw het e13;nt............................... New England eNortbI 3.334 ~22 Parence e19141 New Engtsad (South) 1.073.624 Popesae t1 W 4)

Dearee. Cala.,

e Rocky T. ate) 423.698 .g Papeace s tMr36................................ atrs'r*ra. Ca. # saeaana3 3 stehmtdt no.coe senmut 41ML2a) as a and. wn.m. ina fern 54.614.724 ) 1M23 m ai............................................ 1.: 1 the question as to the induence of the facilities rates for each AR3IS ares were developed from on their environs prior to the initial aerial mr-the contour maps in the following manner. Each { vey. In general, the facilities occupy consider-ares map contained up to several hundred dis- } ably less than I percent of the rurveyed arena, tinct radioactivity segments, which were traced and there were no reported or obvious patterns onto Kemfel and Euer Albanene tracin:r paper of radionudide deposition around the facilities. (thickness = 0.0025 in., 302 mg/in.', S.D. = l l In some instances measurements directly over 1.15 mg/in.'). Contour sep ys were then eut plant far;lities were n:fected, and in the<e ea-e4 and weighed the weight bemg proponional to the natur:il radioacri Mvas inferred from local the portion of the area in each radioactivity con. t geology. For example, toc aerial eilluent from an tour. Radioactivity datn obtained over lakes, res-l operating reactor at the AEC's Brookhaven I.ab-ervoirs, and swamps were deleted. since these oratory was detected Wopenoe.1066a), but the areas will not ordinarily contribute to population author corrected for this e:!eet on the radioac. expomre. Conversion from eps detected at 500 feet in the tivity map. aircraft to DE rate at 3 feet above ground was Sodium iodide t.Tal) scintiHation detectors were mounted in the bottom of the mrs ey air. not performed in the AR3fS reports. A conver. [ craft, which were : lown at 500 feet over the sur-sion factor of 1 stem,hr. at 3 feet from 25 eps veyed terrain on traverses spaced 1 mile apart. at 500 feet (for cesium.13~, 0.662 3feT* gamms Although ditierent airetaft and detectors were ray) is reported in many of the AR3tS reports down by the l'.S. Geological Survey and and is based on the work of Davis and Reinhardt E.G.3,G., Inc.. the remits from the two -y,tems (1962). It -hould be noted that the monnenergetic emi9 ion of ee !um 1& is probably not r* pre-are compatible Wuplou.104). Count rate data wmative of the wide spectrum of energies ob-were corrected for the induence of, o-mic radia. tion and then were u.-ed to plot contour maps of wrved in radiation frnm natural radionnelides. A luw ener::t cotaponent from scattered radia-the ganuna. ray count nite :wohing from ternta. rion is e-peciany prominent with these nuclides. t rial.ource.-: the maps acemup,ny the re-pectim In additinu. the mnwesion factor obtained by I .UO!S n ports. 8eural weeks wen nyuired to Ibri4 m.J Ucinhardt i ba-ed on :li::ht< over dis-mney u-t of tbe areu, a:though fou:.:er time-the mrface of :he weie.wa.u nally repotted. tributed point sources on In this tudy, hi-tograms of terre-trial IIE ground rather than over a 'miform S obill:e soutre 2Er i i { i i h 's l

9 f et al. (100S) and Neuschel (1970) for Falcon such as natural t reestrial radioactivity. Thus, it IIcights,3 finn. In this case, the conversion was does not appear valid to use this conversion (25 eps-= 1 givm/hr.) for terrestrial DE rates due 35p _ 1 gem /hr. 00 eps to natural trackgmund radiation. In addition, un, S.6- (d + 1.J) published experimental nork by K. L:rsen (l'ni. sersity of California at in.\\ngeles) is quoted

4. A total of 1G terreetrial measutrments, cor-in the.\\1 DIS reports in relation to the contai*

rected for fallout (Deck et al.,10Gla,10m), bution from fallout. Larsen is quoted by Popenoe were obtained in Denver, Colo., in 1962, 1963, and 1963. The aver. ge DE rate was 11.0 (1000m) as stating that "... a cour.t rate of aPProximately 77,000 cps measured at 500 feet parmehr. The.ilOIS map for this ares gives above the ground by Geological Survey equip-a value of $50 cps in the vicinity of Denver, ment over an infinite fallout =ource is equivalent and the fallout contribution during the.\\IGIS to 1 mRihr. measured at three feet above the 3tudy was 0.37 grem/hr., or 2S eps. The con-ground.. J' or 77 eps = 1 premihr. This ver3;on value is thus value was un d in conjunction with figure 11 in 550 - 2S _ 71 eps order to corred the.ilOIS data for fallout con- - 1 gremehr. 11.6 tribution. Fourtren areas had fallout corrections of less than 1 gem /hr., whereas the 411o.t DE Based n the comparison of aerial and ground e rate in 11 areas was greater than 1 --W h r. data, a factor of 75 cps at 500 feet = 1 grem/hr. Ground measurements were compared with at 3 feet was assumed for converting the aerial 7" aerial data from severa! locations in order to . lata to do3e values at the 3. foot level. In apply. arrive at a conversion for natural emitters. ."E. this factor to the data of all.iR3IS areas, ..7 There are four separate determinations of this 't 28 S*nmed that the source spectm do not '. hang signi6cantly across the (*nited States, conversion: 1.3tacKallor (1002), based on a comparizon of t.e., the relative contributions of potassium.40, mound surve tad aerial measurements, found a conversion of 47 eps (500 feet) = 1 trm/tr. nyanium720s,and thornim-232 dc not change dra tically. rins assumpt n is suptwrted by the at 3 feet. Ilowever, the ground and air meas. e untrywide spectrometric surveys of Beck et al. urenients weit taken it' rears apart. during (1064ab.100Ga). In addition, the utthty of aerial ~' which time the dose contribution to fallout survey data has been enhanced by the demon-changd hv 1.0 gem /hr. When this dhrerence etration that the DE rates from potassium 40 is accountcd for, the evntersion is 7G cps = uraniura.205, and thornun;232 41ww almost ex- ~ 1 gemAr. actly the rame vanation with he,ight (Beck and

2. Levin et ah (IDM) reported an average DE h" Ph*4"** IPUSh rate of S.5 gemshr. in f.ittle Falls..TIhin. (76 ne pnw um in ;umly7ang the aem. i dsa may

[~ l measurements): the.\\lDIS data map (Neu-then 1e rununarized as follows: .,[ schel,1970) for this hication presents an aser-the twa. 0.0 counts / ec. at 500 ft, minus fallout correction ap of 275 eps. To emupa e girm /hr. ( f allout in sununer of 1965 from _ eps,,grem/hr. y .s gg Sg ire 11) and 4.3 pivmrhr. (!onizing compo- = gremehr. at 3 ft. 9 nent of ersmic radiation) were 3nbtratte I from j ], the ground value; the fallout value from figure The data wete then grouped in e prem/hr. inter. 11 in the -mamer of 1961 was 13 premihr. vals in order to arrive at Hgures 13, which pre. or o..I x 77 = 20 eps. Tims, 3ent the liereent of each.ilDIS area vs. DE I p rate. The as crace DF. rates of the.\\lDIS areas 275 - 23 IG CPS l I - 1 gem. hr. varint from 1.:1 grem. br. in the Oriando. Ph. e S.5 - to.0 - 4.3) area to in.00 getu/hr. in the Ilocky Flats.Dem er, j l

0..\\ Wmilar cempatie.ut was made from Levin Colo. area.

a e 35 f 1 i ~. - - - ,m--,-----.-,.,+---,.,- -.-----.,-,y r- .---e-

a le U NORFOLK.VA. (el 4 3 f j m II f M. MER ENGLAND (a) L, 4 j, 3 i f to u t I t f f f 1 h, Y PARR,1 C. (f) $3 = n l 5 NER ENGLAND th d g E

1. 0 3

5 8 = 4-a ee 4 5>3 l s { ~~. 5Av AWAM RNER AUGUSTA. 3A. fg) I 5 2 s I ~ so a sa O i 3! 3 e i i e i 1 ,4 t \\ sg l s o CAv;EN PMfLACELPHIA (c) i 3 l 63 i g I t I f I f OAPE KEuEDY ORLANDO. FLA 00 43 l sg t FCRT SELV0lR, D C. it) 3 23 i g i 3 3 2 4 6 8 10 !! I4 'l 0 2 4 6 8 13 12 14 il y PEu

• R.

1. REW

.4 R. Figure 13. Do-c.quis sknt rates in tRMS areas (mcan denoted by arrow) l 26 l 1 l s' % ~

i /

• 9..

q i n 40 = \\ GECR !ANUCLEARLAS. i l ATLANTA,24. 61 9-og 3 C;NCINstATL CHt0 W i 3 O' 4-I l i i i 1 e i n g CAK R CGE. TE4ft. Q) 68 - .'3 CHICAGQ,ILL. ial se l i gI 63 - 5 1 3 4 n a 4 ~

>5 34

= PITT53UROM.PR. 1) !,E 2 e e i i 2 g = ~ s 4 a w I 2 83 ' ] O h 2;wEAPOL!5.V;hN io) i a 4, 4 I

o. :g I

i i o U gg,. i e e e i 1 I g 53 - 63 - I COLLv!U3.0+0 (!) f e g s so n l

ALVE5 TON. TEt. im I,

J e 4 I

3 t

0 I l 9 i l i i 3 3 2 4 6 8 13 !2 le 16

I 3

2 4 6 5 l0 12 14 il i g u REW n R. y REW MR. I Dose equis alent rates in AlutS aress-Continued I Fi;2re 13. I (mean denoted 53 arrc=) I f .l *6 e c ..__,_ ~ - I --,-,cn--,n--,.-,-,,,~~ --,-,- n. .--,---,v------,---

n- ~ J 40 's 40 c-t 40Caf FLAT 1 Cttute C3LO w g I 1 i l E E J f a t t " PA4FC#0. mCMLAh8 4ASM M I, ~ as 3 AL8UQUERQLit 4 M g) g i i w a i It = 1 64 l i e e e e e i 4 4y za Et } !AN FRANC;1CO * *,Lif. (e) 2 3 M 3

ARL!!A3 iG9:Wik 4 M. (St Y

W 5 !j I I I a e i s a T a i me sc, 10 = j ,, ELLO.*.AnTA I APS ARA. CAUF. al 9 2 l 9 F" 3 l 3,, %4T3 iCA*0 F ALL3 i AMO m 8 a i i i I t r e r e s t

p og

^ es cartet cAur. si 3 LA3 4 t* A3. C 'st 3 i l 1 I I n i i t e i i i i g 3 2 4 6 8 10 12 :s 16 3 3 22 24 8 2 4 6 8 18 12 14

S l

9 Fin ~R. p 9tu nn l'igure 13. Dose equivalent rates in.\\R) S areas-Continued i (mean denoted by strow) l i i bh

• e k

Each histogram covers between 95 to 100 per-high background ana of Denver and measure-cent of the regevrive AR3!S area with the excep. ments over unpopulated granitic oute:S4 in tion of Las Vegas, which covers 95.2 petrent of North Carolina; this could explain the higher. i overall mean. the ares. The totals do not add up to 100 percent Three distinct areas of terrestrial radiation are in each ease since the count rate data for 1 to evident from an analysis of the AR31S data. 2 percent of some areas were presented in very broad contoun (i.e.,1,200 to 4,000 eps) relative Fint, the Coastal Plain, bordering the Atlantie to the rest of the map data. In general, the Ocean and the Gulf of 3fexico, has a terrestrial j radiation level of approximately half the U.S. omitted portions covered unpopulated areas such average. This is pcrtially evident from the mean as mountainous terrain. The highest count rate found in the AR3fS data occurred in the Las exposure of three areas lying entirely on the Vegas area (Guillou et at,1963) and the Albu. plain: Norfolk (3.00 3 rem /hr.), Orlando (1.51 querque area (Guillou,106Cd), where a maximum grem/hr.) and Galveston (0.26 premar.). The of 4,000 eps was observed (50 grem/hr.). In both Coastal Plain includes marine deposits of Qua-l cases the locations were unpopulated; the Albu-ternar3, Tertiary and Late Cretaceous age (Neu-schel,1066: Schmidt,1067a) and is shown in querque area maximum cceurred in the vicinity of a uranium mine. figure 12. Neuschel and Schmidt observed in their re-The original AR3t$ data are grouped in count intervals which commence at zero eps, and this is spective reports of ARSIS surveys (Washington, retlected in the hi>tograms, which in most in. D.C., and the AEC's Savannah River plant) that the portion of the area on the Coastal Plain was stances crimmenee at a zero DE rate. Therefore, considerably less radioactive than the rest of the it should be noted that the zero DE rate repre. area. In order to quantitate this observation, the sents the lower limit of the AR3fS reporting radiation levels of four areas which straddle method rather than an actual e-timate of DE the Coastal Plain were studied in more detail. rate. The mean DE of each area was computed Table 13 summarizes the DE rates of the total 8 f by assuming that the midpoint of each DE inter-and partial Coastal Plain arva. It is interesting to val (1, 3, 5, etc.) was representative of t'he DE note that the average radiation level in the non-for the 1eepective intetval, and the means are Coastal Plain portion of the mixed areas is simi-designated by arrows on figure 13. far to the U.S.." rage. By weighting the individual distributions of figure 13 by the populatioa of each area, a :um-1 mary histogram was obtained (figure 14), of Don muivalent rates in areas on or straddling TrMe 13. which the mean is 5.0 prem/hr., or 44 mrem /yr. the Coastal Plain As shown in table 11, the overall mean of 0,00G k measurements bV bevin et a!. (1963) iS II ?!.on J.4.1utratent rates " ""^ " l mrem 'yr. If the ionizing conymnent of cosmic c l,/,, c,ey N* radiation is assumed to account for 3G mrem /yr., c,,,3 ^"* Na Na 2"* then the terre-trial DE is 41 mrem /yr., which to eo aa compares well with the mean obtained from the cm.%-ru:aur[u...........l! O UlrY.."J..I."'.'..".Y.7.:: AIDIS data. A summary of 210 ground mrsey meneurements (Deck,10cGb) al-o is pre-ented in Zonva~iiiF::::::::::::.- U U i," f figure 14, md, as can be seen, the mean is ap-NM?,*,,:::::::::::::::::::: O M i av..r n.............._ =c i u u pnwintuely N percent higher than the valun derived h.im the AIDIS data. The locations of Ucek's i :?mb) measurement s a re not gis en : in order to compare the Coastal Plain and non-howes er, t!.e n.ca-urements are a >muniary of Coa.tal P!in n gions graphically (ewhnling the dat i repotted in Ikek et al. (INtab, IN6a). The Denm-AlOIS data), the A] DIS d.na for each ,i latter icierens es inclu.ie 16 mearurements (ram:- ing from 7.1 to 15.2 grem/hr.) in the relatively region were population wei;;hted in the same I 29 t Ng

l. B t t. t lj

SUMMARY

ARMS MEASUREMENTS i

o i i I = 4.98 y REM,HR. i a< 30 43.7 MREM /YR. l r = 1 7 a: i x s 20 =

a,

~ i

1. 10 l

I O 1 i e i i 0 2 4 5 8 10 12 14 16 18 20 REM / HR. 5 20 I

SUMMARY

210 HASL MEASUREMENTS (BECK,1956 b)

33 i = 6.97 p REM, HR.

= 61 mREMiYR. E l 1 .i = -T H T E 20 I ~ l 5 t =, i i g I N l

1. 10 t

e l 0-I i i i e i m i r-, ) 0 2 4 6 3 10 12 14 16 IS 20 y REM, HR. Fin re 11. Dose equirslent from terrestrial sources based on population. cighted .11D15 data

',0 i

e

• %m e.

s wy s---- -we,- ns,,,s ,n w, -,,,7 ,,.,,,,-,---r-r r -w--,-----g- -+-e e, w mw

./ I L k i t' manner that was used to obtain figure 14, and the in increased t diation levels over the region of E resulting.listributions are pre ented in figure the de;.mits. There att no reported measurements i

15. As can be seen, the DE in approximately so in the region, which is sparsely popuisted, and t!iere are no other significant deposits in the en-

[ percent of the Coartal Plain area is less than 4 tire Coastal Plain. Recognizing the limitations on [ gretn/hr. (35 mrem /yr.), whereas mosc of the data from the Gulf Coastal Plain, it will be non-Coa >tal Plain (64 petrent) lies in the range 4 to S givm. hr. (35 to 70 mrem /yr.). assumed that the Gv1f and Atlantic Coastal Plains fol!ow the same pattern of producing low terrestrial radiation exposures. This assumption is based primarily upon the fact that both aress i have similar geology, i.e., marine sediments de- {l posited since the late Cretaceous age. The second region of the l~nited States, which I stan is apart from the rest, is t'.. Denver region i

x,, y,

of Colorado. Based on the ARMS data analysis, i'""

• a the mean terre = trial DE rute for the Denver area i

i! is 10.2 grem/hr. This is approximately 40 percent h'gher than the next highest value of 7.3 grem/ 4 hr. ( Albuquerque tres) and twice the average = l j, i of all the ARMS aress. Phair and Gottfried I } (1964) found that levels of u-anium and tho-s rium were twice the normal crustal concentra-j "" tions over a 7,000 square mile area along the e j Colorado Front Range. Fmthermore, they ob-8 eerved that the Front Range was the only large i 7

7..*f,'l,I "[

area in the United States in which the uranium l and thorium concentrations in bedrock were con- ~ 4 sietently above a.erage. Much of the Denver sur-l f vey area is over siluvis derived f-om the Front de I Range, an i the aerial data and the previously t i mentioned ground dats (Beck et al., 10643, a a 10662) corroborate the measurements of Phair se:t tmtit. u nts.* and Gottfried (1964). There is no evidence to i that other areas of higher terrestrial rigure 15. Dose equitstent from terrestris1,oureep m:"m-t , Cossts! sed non. Coasts!!! sin repens rad > tion and comparable size to the Front Range m e exht in the United States. The arens of table 13 are all on the Atlantic Levin et ah (19G5) obtained ground readings Coastal Plain except Galverton, and therefore it in 11 Colorado towns, none of which were in the I is a>sumed with less certainty that the Gulf 'enver ARMS area. They found terrestrial -- Coa 3tal PIain fol!o.vs the pattern of lower radio. s osmie - fallout DE rates of 11.0 to 14.6 activity that was ub-crved in the At? ant! Cuartal P'ain. The *ntatal radi%tisity of dulf and givm3r.: the average of all Colorado measure-13.3 gremfhr. If ecsmic radiation Atlantie i.each sands has been shown to be rela-md fallout (1066) are.usumed to result in 7.3 ments wa:,

heir uniform (Ehdavi. IN4): y et this fact n hmbably not th related to the radioattivity grem hr., then the average terrestrial DE in CMorado outside the ARMS area is about 6.0 of *.c et;re C..a-tal P!ain nce Whd.o i's +am.

, s m retah n en ud near the k t hes. Signis. g:vm hr.. which is similar to the va'acs ob-nr- :inm.nv deposts esier in the Tertiary tained in many of the ARMS areas. It is portion of the Cmstal Plain of wuth Taas not sm gested that natural background :evels ant i Fbch. INT), and the derMts may be rekted vary according to political unE The laet is. r 31 N e%W 2:_

1 1.mrever, that New 3fetico, Colornilo, (*tah, and used in chaptrc 4 to compute the total DE due %~yoming are the principal 'tranium cre-Learing to natural ra liation. 5:ates (Finch, IN-), and it is not surprising that areis on alluvia derited from ore rich regions Table H. Due equivalent rate frosi terrestrial sources aonld have I gher background radiation levels. based on population weighted.UOt3 data If the Cwtal Plain anri Color.lo n.ay be con. -Iared as the location of Imr at:.! 1.igh values of 7lf,",'l,"g ,,,J,7,,, termtrial radiation, than the balance of the Ana m is ineos onn=/ir. I*t~..ted States represents a vast 3Iiddle.\\lucrica. cose'ai P!ata.............. 6.739. tit 23.8 ,i;i :ngically speaking.1 auiamary of.iRMS. "$,?'E,.."!".'."..!'.'.'.'.".*!* * .mi.23o 4s e D"-"-~^ leiived DE rates due to terrestrial sources is ^""" . teented in table 14, and the<e e,timates will I.e - - ~ ~ - - - - - - I i i i -1 I 1 ) .i t k a J 3 i i I t .:2

t ..ue

re CHAPTER 4. NATURAL RADIATION EXPOSURE OF TIIE U.S.

POPULATION ~ In the preceding chapters, two major natural provide the potential for updating exposum esti-contributors to population DE have been consid-mates in the future as new census data bettme secondary reason, manmade ered. These m (a) cosmic radiation and (b) availaue..\\s a terrestrial radiation. In order to calculate an sources of radiation are concentrated around average and range of external DE in the United urban areas (hospital use of x rays and radio-States, it is ne.essary to consider the induence nuclides and nuclear power reactors), and this of population distribution on exposure from each model may facilitate the computation of total of these two sources. Initial calcidations are di-natural and manmade radiation exposure. rected to the determination of esteinal adiation For each popuhulen segment, the co3mic ray DE from these two sources outdoors, and these (ionizing and neutron componems), terrestrial, estimates will then be modified m this chapter and total external radiation DE rates have been l to consider the influence of hou3ing construction calenlated. The cosmic ray DE rates due to ioniz-and .m's bid,gical aielding on DE to the ing and neutron radiation were calculated ba.-ed gor.4 % and bone marrow-on the elevation of each segment and the data

7. resented in figure 6. The terre 3 trial DE rates r each population *gment uere anigned on the 2

4.1. External Sources' basis of general estimates from table 14, execpt The calculation of DE from external soarces in the case of those urbanized areas (40) which has been performed by considering the popula-De within the boundaries of.\\R.MS areas. There tion to be located in either urbanized or non-areas have been assigned s DE which was ob-urbanized areas; an urbanized area, as desc' A i tained by con'.erting the measured cour.: rate in by the U.S. C<.a.s Bureau, S a dty (includ.pg the same manner as iliscussed in Chapter 3. suburbs) which nas a total population of more The results of the computations for each area than 50,000..\\s of the 1000 census, them wem 913 are shown in appendix.\\, tables.t-1 and.\\-2, urbanized areas in the United States, some of and a summary of DE estimates is presented in which overlap adjoining States. The nonurban-table 15. The data in the table are pre 3emed :n zed areas of the 50 States are treated as addi-tuo discient ways, urbrized vs. nonurbanized t:enal.-egments. Thirteen of the 50 States lie areas and Coastal Plain vs. non Coaetal P!ain. l partially on the Coastal Plain as shown in figure First, the mean and ranges of data for urhamzed t

19. Each of these States contains two nomirban-aieas and nonurbanized aiens are gis en. The mo,t I

! zed segments corresponding to the Coastal Plain significant diderence in the two groups is the and non Coastal Plain portions, and thus there average and range of 6evations; urbanized areas are 70 a 13 = GO nonurbanized regments. The range in elevation fimu 5 feet iNew 0:W n s. total riml+r of areas is 310, 2C of which are I.a.) to.. M feet Calan.do Spring. (;Jo.i. 1.en as the nona..:. zed :np dation !!ve3.: urbanized and 4 of which are nonurbanized. v a rmgin, up '6 1.V.4 (Leads ille, C.h.. Urbanized and nonurbanized areas were se-a ren lected as the basis for the nelel because they and vicinity). The tmestrial DE r....gca "nuu da b ~

s i l 1 Table 15. Dose equirafent Outdoors fross terrestrial and costnic radiation 0960 census) i Populated etees. Ceamte rar DE Terrestrial DE s Total estersag tate. I t1ee treet) t area /yr.) t area /ir.) DE ' a mrem /yr.) Dk*4 8 Populattes 3 feen Range >tese Range 3 fees Passe Steen Range maa. rem) t*rbanteed areae....... 93.e4 s.4 57 491 5-5.990 48 40-83 41 0 120 SS 40.*00 LO Nomurtpanteed arets.... 63.474.658 945 0-10.7,00 45 40-160 40 0-120 85 40 300 7.1 c%astal P!sta.. 32.143.217 170 0-400 41 40 42 24 0-90 65 40-130 2.1 .%sfos*tal Pf ata..... 14 r.1 B2.'sSS 824 6-10.500 44 40 160 44 0-100 38 40-300 13.0 t* s. *u m n a ry......... 173.303.735

07 0 10.300 44 40-160 40 0-120 54 40-300 15.1

• r.ouer and upper !! mite correbnd to enluet presented to Srure 15.
• Totals are twa =t upon the comtJnartoe of evemic rar and ter re. trial areas. and the total t*ntted states. hhee t>een rounded of to 300 taces/y.DE. The DE*s far the neaertranteed and non. Coastal Ptala approximately 10 mrem /yr. (12 mrem /yr. in IS percent of the population, are rettected in the Orlando, Fla.) to 02 mrem /yr. (Denver, Colo.).

larger integrated DE (man. rem) of the non. At present, there is no reason to indicate that Coastal P!ain population. the populations of urbanized and nonurbanized Summary data for the entire 1*nited States are areas have ditierent exposures to terrestrial presented in the last line of table 15. As can be sourecs. A similar conehtsion was reported by seen, the average DE of the population due to Segall and Reed (1064), who found no ditierence terrestrial and cosmic ray sources is S4 mrem /yr.; in DE to re<idents of urban and rural regions in this value will be used to calenlate the gonadal q' New IIampshire and \\~ermont. The total DE due DE in rection 4.4. The distribution of the popu. to external sources is also practically the same lation vs. external radiation levels is presented for both areas, and the dirren nee in integrated in dgure 16. In order to determine the overall exposure (man. rem) is due to the difference in distribution of population DE in figme 16, the lopulation of each group. terrestrial DE in each population segment was It is interesting to note from table A-1 that assumed to be distributed as shown in figure 15, the lowe3t cosmie and terre-trial DE estimates except for those segn.ents in ARMS areas for both occur in areas on the Coastal Plain, and the which the terrestrial DE could be directly esti- { highe-t values of each occur in Colorado. For this mated. In other words, those population segments reason the re:ults have nIso been divided into the in table A-1 for which a general estimate of ter-Coastal Phin and non-Coastal Plain regionsi restrial DE is given (22.S or 45A mrem /yr.) l Denver has been placed in the latter category in t this classification. As e be seen, there is a large ditierence in the range: 1 cos.aie and terrestt;ist 3 l DE in both regions. Although the mean of cosmic l radiation DE is approximately the same in both regions,it can be seen that the range of DE in the "I i non. Coastal Plain (40 to 100 mrem /yr.) is much 7 l greater than the range in the Coastal Plain (40 g=- l to 42 mrem /yr.). In contrast to this, the mean 5 terrestrial DE of tl.e non. Coastal Plain region is I :t nearly twice that of the Coastal Plain. This is as L expeered. Since the terre trial DE estimates are l based on the results of the ARMS mrveys which ucre summari7ed in the previous cl. apter. As :s % n re. ult of the ditre:ence in t2rtestrial DE. there ".et$t

• s.ns

9 ::

cu. L rab'e di:rcrence in the total DE of the 4 twa n gions. The ditretences in total DE in addi. ri;ture is. Population distribution

s. dose equis alent tion to the fut that the Coastal Plain holds only frorn terrestrial and cosevic radiation "a

l l c e- - - ~ ~ -, - -- -~r----- c

/ were. assumed to have a variation in terrestritt in figure 15. The contribution of the Coastal DE as shown in figure 15. A cumulative distribu-Plain distribution of terrestrial DE, which is E tion of population vs. DE is presented in figure skewed strongly to the right, is muted in figure 7

17..is can be seen, virtually the entire population 16 since only 15 percent of the population resides receives less than 170 mrem /yr.

in the Coastal P!ain. 2 1 4.2. Attenuation of External Sources .0 .{ The estimate of man's DE which was presented in section 4.1 is that due to natural external radi-w. ation sources and is based on outdoor measure-g ments. In this section, the errect on the DE of i8 [V housing construction materials, biological shield-the ing and the contribution of internal emitters, an- !j= principally potassium 40, will be discussed. j - m 4.2.1. IIousing a .w Inasmuch as man spends most of his time in- ] Q'

m n.d..in fsa doors, the nature of construction materials will influence his exposure to natural sources. In gen-t eral, the interiors of stone houses have the highest T!gure 1. Cumulative distribution of population va.

dose equb stent from terrestrial and cosmic tediation exposure rates; brick and frame houses have the U next highest. The alr.ount of time spent indoors The distribution in figure 16 should be re-will, of course, determine the importance of con- [ garded as an approximation of the population struction materials as a source. Estimates of both distribution vs. external DE since the distribu-factors, time and the amount of natural radio-tion is based upon serial surveys of terrestrial netivity in building materials, are based on rela-DE rati:er than on estimates of population DE tively little data, and probably represent the within the survey areas. It should also be noted greatest uncerta:nty in estimating man's exposure ,8 that the distribution is based on the two quite to natural sources. d diferent distributions of terrestrial DE in the .t summary of indoor measurements is pre-Coastal and non-Coastal Plain regions, as shown sented in table 16..ts can be seen, exposures in s Table 16. Ratio of indoor to outdoor dose equitaient But!d!ag reatertal Ratto of tudoor/ outdoor Cnntry and reference touter wans) og ce; Recarts l Solen et aL (1960).......... Frarce, brick, and etsce apart- .irgros. so.100 It du el!!ngs n (* cited 5tates : cients and houves I (*.:1!<4 9t stes : 70 160.teg!e tomes Lw der and Cenden (1963).. ?tostly wood frame half frsme !) 46* !adoor measure: nests D t Germaar: {'b Me t Chtsen t D69).............. 109 Fre-1945 stene it g 7 Stngle hottes and apartments t,rict l' Tast 1345.;prefibrtcated 65 66 '.mtsed All but:1:n gs $2 300

• 0 um.ure n-nts tra 3* new Pen io et si.

W 3)....... Cenerete ani brtet spsitments t*r!!^t Pstes : 52 % -t r..!* b":ee.1.t.9er i re ites et a.. i!3*0) F- .e 94 1 a;+triment. dd Lor r r:< a 57 106 4 o.".ce t.u1 Min.-s [ Steel and concrete e 75 110 *tecte homes I*..it *4 S t a t es : I.:nd. ken et al. *1471)...... ?!avely no.1 fr.tme e'licc ) 35 .e I i .... ~ - - - - y -r w-..

I 1 frame dwellings are 70 to 50 percent of outdoor sexes, the least attenuation (i.e., highest semen-values. In masonry buildings the percentage is ing factor) occurred in the standing position, somewhat higher (50 to 106 percent), which indi-the greatese attenuation was provided in a hori-cates that the DE from nuclides in the building zontal posinon, and intermediate attenuation oc-i material partially orfrets the attemtation of out-curred in a sitting position. i door termstrial scurces. It is intere-ting to note More recent work by Bennett (1970) indicates that the second41oor men-urements by Yeates et that the gonadal screening f tetor, averaged over 8 al. (1:W) in ringle family frame houses aver-both sexes, is 0.S2, and a personal communiention nged il pervent of the drst.rbor measurements. from Bennett indicated that he believes the bons In a multi.-tory building of masonry construction, marrow screening factor also to be closer to 0.S. however, there is no appannt variation of the In addition to discussing limitations of earlier i DE with he ght in the building (Ohlsen,1070t work, Bennett also has inferred similar semen-Pensko -t al.10G9). The comprehensk e measure-ing fators from work by Jones (1066) and Clif-o ments by Ohhen indicate that buildings of more ford and Facey (1070). Based on these data, it recent construction (since 1943) tend to have is assumed that in the present work 2 screening L Imver indoor DE rates than older buildings, facter of 0.S describes the biological shielding of 1 at least in the German Democratic, Republic the gonads and bone marrow by overlying tis- } (DDR). Although buildings of " mixed" con-sue. The shielding factor is assumed to apply to struction materials may include a number of the termstrial component of background radia-variations. the low inside DE ratio for this type tien and not to cosmic radiaticn, which is more } of construction possibly retiects the increased use penetrating. This is the same ap,s.oach used by a ~ nf glas. plastics, -teel, aluminum, and other ma-UNSCEAR (1962,1006). terials containing telatively little natural radio-activit y. 4.3. Internal Sources In nrder to determine what erfect buihling con-3rrurrion might have on natural exposures. it is This studv is devoted primarily to natural ex-necenary'to make as-umtulons on how people ternal sources of radiation, which have been dis- -pend their tinje in s arious activities. A basic cussed in the preceding sectionst however, in rpn.nen to t!ns problem has been w n in ap-order to arrive at an overall estimate of whole pendix B. in which it is estimated that indoor body exposure. the contribution of internal nat-living it.d its of the United States msult in the urd emitters aho must be considered. population receiving 50 percent of the out-The average potassium content of the body is door DE. about 0.2 percent. On the basis of g Kag body weicht. males show hicher values past the ace ~ ~ 4.2.2. Biological shielding of puberty, but this is related to the ditierence The estimates of DE in section 4.1 are for in fat content of the body since fat contains rela-tinue with no self--hieldine. Since the conadal tively little potassium ( Anderson and Lmgham. DE and lone marrow DE aie often used f'or dose-1953). Femaics have more fatty tissue than males risk a.--e ment, it is necessar* to determine the and therefore have a lower ratio of g K/kg body miec nf !aildup and attenuatica of radiation in weight. Ninety percent of the tissue DE from the overlying t ssue. The most widely quoted ref-potassimn-40 is due to,7 particles (range = 2 crence on this subject, UNSCEAR (1902), reaom-mm in tissue); the remaining 10 percent is due to aends a sercenme factor of 0.6 for ennadal and g:nnma rays (Rundo,1960). Therefore, the tinue !.. ne wrrow dose rates frem terre-trial radiation. DE is largely determined by the potanium-40 ~ This N ror was pirt!y ba-ed on the work of ce ncentrations within the tissue in.p:e-tion. Sp:ers i1954, who found that terrestrial gamma Ganadal con.entrations of t+ta--ium in the rm:iation was reduce l by f.u tors of 0.52 to 0.59 l'.S. Impu!ation are 0.2 percent and 0.14 terrent ih pendine on the lody orientation. In males. the for males and females, re pectisely (Tipton and -creerdng fae:or varied from daG to ".72. In loth Cnok,19%) : these eeneentrations correspond to m T...---- - ---.

/ DE rates of 10 and 13 mrem /vr., assiming the Estimates of DE to the bone martow from in. convenion factor calculated b, Rando (1960). ternally deposited nuclides are 15 mnm/yr. Le. For the purpose of estimating ganadal DE. an cause of potassium.10 and 2 mrem, yr. because of averate of these two vah:es,10 mrem /'vr., will be the other nuclides mentioned'in section 4.4.3 assum'ed. Other internally deposited natural (UNSCE.\\R.1066)..is has been discussed. the nuclides, principally rubidium S7, carbon.14, same biological screening factor is assumed for radium 226, mdium-OSS, polonium.216, and bone marrow as for gonads, so that the bone radon-222, are assumed to nsult in DE rates to marrow DE from terrestrial and cosmie.wmrees f" the gonads and bone marrow of 2 mrem /yr. is the came as that pre-ented in table 17. or 70 i* tUNSCE.tR. IN6). These estimates will be pre. mremiyr. Thus. the total bone marrow DE from eented in section 4.4, in which the overall esti. natural sources is 57 mrem /yr. mate of population DE is made. The estimate of genadal DE in table 17 is con. [ s'd.erably lower than the UNSCE.\\R (10ta) "orldujde estiniaa 7, les tuum/yr, wWi is f 4.4. Dose Equivalent to the Gonads often ened m, tne I. mted., tates as the -baw. and Bone Marrow wh. h manmade I.me radiation level against ic Talde 17 presents a summary of gonadal DE to mdiatioti sources are compared. If the reintive the U.S. population. The estimates for co-mic and importance of manmade sources is evaluated by terrestrial expo-um are based upon the results comparing the magnitude of manmade and nat-of section 4.1. and the terrestrial DE contribution uml radiation DE, as is often done, then it follows that mamnade radiation sources must be con. sidered as a more significant portion of man's Table 1*. Gonadal do<e equivalent to the (*.3. popula, toul exposure to ionizing radiation. tion frons natural radiation 4.5. Discussion D->e m.m/ r. uivalent source i m r, r e st The estimates of DE in the present work are d2.Nr.Ri.Tr"="GTC.~.GTa~TiiT-based up(m measurements :md census and hmt.-ine clY ' i.T.'.7. 2.".'.7.'.'.7.T22.2'.22. data from many diderent sources. For this rea. u son it is not poeible to calculate the variance of N Z'.).um4o......................... the end result in the conventional manner. It is a o ui. uwe....................... po<sible. huueur, to discues the uncectainties rmt ................................I ss which adect the separate components of the over-all totals and. L ued on the uncettainties. to e-ti-has been reduced by the housine and ennadal mate the accuracy of the several import:mt x reenine firtors of -ection 4.2. As can 13e seen, factors. T:.ee contributing errors are taken to the est; mate of DE to t!.e conah fre.m natural repre:ent in each ease a sample at the 07. petcent radiation sources is M mrenhyr. Since all mem. prc.b..bility Lvel drawn from a normal popula-I ers of the popularian are exposed to background tion of ob ervations. radiation, the.:anadal DE :s m. uivalent to Cosmie radiation acenunts for approxintuely the genetically Ygniticam DE. It '. l!d '.e noted 40 to 70 percent of the external radi.. tion DE to that the reduction of terrestrial radiation con. the U.S. population. The ionizing and neutron tribution to gonadal DE is 14 mrem 'yr. due to components contribute about 55 and 15 percent. bio'occal and housine attenuation. I!vwever. this teepectively. of the ecsmic ray DE. The e-timate relu3 on is ndset by the enntr!! ution of Mternal af the.-ea. level 1-nization vahtes. from a hich the l mitters i S mrem yr.). With this.n :ui".d. It DE e-ti utes are derived, is probab:y w ithin 10 can be seen that druvs N ; nd 17 arc t% rea+0n. per.vnt of the it:.e vahe: howewr. the eaa.ie el s

ble approximations of the pc.palation d:striisu-neutron vane may be in error by as much as 50 l

ion u. ganadal DE.

ercent..is a result. the co=mie ray DE at a 37 e

4 P

specified elevation is probably w; thin 12 percent example, the DE from weapons. testing falloct was 50 percent or more of tiie natural terrestrial of the true value. DE. As a re ult the DE estimates for the AIO!S At this point it is appropriate to discuss the areas are probably within 30 percent of the true uncertainties present in the determination of the value. Most of the locations in ap}wndix A were terrestrial DE, which is based upon the aeri:5 iats assigned terrestrial DE values based on location conversion values discussed in section 3.5.3. In ---either Coastal Plain or non Coastal Plain. this regard, there are three olwervations to be These estimates may be in error by 50 percent. made on the convenion detemination. Fine, The estimate of the contribution of internal thne of the four individual conversion determi. emitters to gonidal and bone marrow DE is nations (1.,2., and 3.) in section 3.3.3. required probably within 30 percent of the true value. a cosmic ray correction. The telationship is such The cetimate in this work is slightly lower than that, for example, a 10 percent decrease in the the commonly quoted D'SCEAR (1962) e>ti. cosmic ray DE will result in approximately a 7 mate of 25 mrem /yr., and this is due to the use percent increase in the terrestrial DE estimate, of more recent and ecmplete data for the potas. i so that the net edeet of a change in the cosmic sium.40 watribution to the total. ray DE on the overall DE estimate is small. The bwlogical shielding factor used in this I I Secondly, it should be noted that the fallout work is believed to be within 10 percent of the eorrection value does not have a significant j imluence on the final conversion factor. For ex. true value, based upon the similarity of recent ample, if the fallcut correction in conversions estimates (Bennett.1970). As has already been '*1, 2, and 3" in section 3.3.3. were increased by mentioned, the other major modifying inthience on the natural radiation source tenn is the con. 100 percent (3.2,1.S,1.S. respectively) the aver. tribution and attenuation by housing. Even with age terrestrial DE decreases by 20 percent (from the uncertainties present. in the deselopment of 40 to 32 mrem /yr.), and the overall DE decreaset the housing factor, it ocems unlikely that this by approximately 10 percent (from S4 to To factor is in error by more than 20 percent. The mrem /yr.). It should be noted that a 100 percent amount of time spent outdoors is based on little . Terre,rac in the present fallc.cr estimates will have more than a guess; however, if this proportion a smaller etteet-approximately a 10 percent in. were 0.25 instead of 0.05, the housing factor crease in the terrestrial DE and 5 percent increase would only increase to 0.51. or by i percent. in the overall DE. A summan of the error estimates is wesented Thirdly, since the terre trial and cosmic ray in table is, and as can be seen the onadal DE c DE are approximately the same, an arbitrary is SS - 11 mrem /yr. The error of the bone mar-change in the conversion value (with no chance tow DE also may be a33nmed to be the same. in cosmic ray DE) will have a maller impact on The error calculation tends to impart an unin-the combined e>timate. For example, a 10 percent tended ense of precision to the ovt rall estim:.te. change in the convenion value (and terre., trial Therefore, one may wish to say that the estimate DE) will result in a 5 percent change in the overall DE. The average terrestrial DE estimated for the Tabte is. Estimate or errors in deterrninin: the gonadal entire l~nited States is probably within 20 per. dese eq.hatent (apr.ndis C) I eent of the true value. Support for this belief j rests primarily on the similarity in AIDIS esti-v 314e

• stimate I'a ra met et mates of grcund DE rates and the spectrometne 4o s

wr rr f rm tm................. data-DE e>thuates bv Beck (10 cob). The accu. racy of DE estimates for individual A101S Y O d.I ifi G '::::::::::: 3 1 a4 3 c ~ me rm...................... is s reas and.:b:uu.ted areas with.m AIDIS areas := aa rn a e r................. o u rtwnely in:hienced by the accuracy of the weap. c.+.4a r6 c..................... one fallout DE daring the time o( each -uney. . %,,,3,,,3,,,,,,n,,,,,,,,,,,,,,,,;a p c,,, a, t.

• =

During much of the 1961 to 1063 period, for 8g,S,,f e5f.Myrg:M;yr N. g ns k

,i i , 1* '.u t of the average gonadal and bone marrow DE is sample than can be associated with previous 2*I approximately 00 mrem /yr. ground surveys. In addition, the same data indi- ,S In summary, the average DE from terrestrial cate the existence of three liainct areas of ter-radiation (unattenuated by housing or biological restrial '.sdiation in th., United States. Through 'C' shiehling) and cosmic radiation to the U.S. pop. the determination of the l'.S. population distri-ulation is S4 anem/yr. There are three distinct bution vs. elevation, it is now possible to cite area: of different population DE-the Coastal State.to. State ditTerences ia cosmic ray DE. Plain, non. Coastal Plain (excluding Denver), The present data may be md as a guide to the

• I and Denver vicinity. Eighteen percent of the average U.S. background radiation eximut and 13 population lives in the Coastal Plain, where the as reaxmable estimates of background exposure mean DE is 65 mrem /yr., and 52 percen: lives in in the areas for which.\\lUIS data exist. Caution

( non. Coastal Plain regions where the mean DE is is advised when using the total DE estimates i SS mrem /yr. The Denver arcs which has appmx-for Identions in which general terrestrial DE 3 imately 0.5 percent of the population, receives values have been assigned, although the total DE 165 mrem /yr. Population DE in the United estimates for these loentions are of value in assess-States probably varies by a factor of 7.3, from ing the :vlative contribution of cosmic ray DE. approximately 40 to 000 mrem /yr. The DE c:timation procedure outline e in appen. In view of the uncertainties which atfeet the ilix.i may be refined as more specific data be-U development of natural radiation estwure esti. come available on natural radiation DE rates in mates, one may question the impmvement of the various scetions of the country. Similarly, infor-results over earlier estimates and the u.* fulness marion concerning living habits may easily be L of the results. The use of the.\\IDIS ilata has factored into the computation, and the author i provided a basis for directly estimatin:: the nat. wouhl be grateful for any information which ural exposure of approximately 00 percent of the could be used for updating and improving the p U.S. population, which is a considerably larger townt DE estimates. 1 L I s .sh

/ 1 4 .1 1 l SLDDIARY i Natural background constitutes the greatest ods were sought and an answer was (cund in the source of ionizim nidiation to the wmbrs impu-series of.UOIS conducted over major arnas of leion today. Thiz exposure is by no means uni-the (*nited States under sponehip of the aEC. form for all Individuals, but varies because of n A second m tjor component, of natural back-munber of influencing factors. Such factors in-gnmnd expo 3ure to the population is roemie. ~ cbule al!!tude, geological featmvs, and living nullation. The DE from this -ource was enm-habits. The twulting variations in exposures puted on the basis of knowledge of the distribu-often execed these faom manmade murces which tion of population with elevation. The third, and generally receive considerably more attention. For last. major component of population dose from example, although no detailed overall.-tudy of natural backgtmmd, that is, eximsure from natu-the subject has been made, publi,hed data indi-rally occurring radicnuclides deposited within the care that the genetically significant dose equiva-body, was calculated on the basis of publi hed lent (DE) from natural background in the information. Once data were available for the DE l~nited States nmges from 50 to 200 mrem /yr. from each of the three major components of nat. A survey conducted by the l'.S. Public IIcalth uml background, a combined e-timate of the total Service in 194 indicated that the ecmparable .smic and terretrial DE was inade takine into Jose from medical a radiation was only 55 . count what is known concerning the di-tribn-mrem /yr. Other sources, such as nuclear reactors, tion of populatim by elevation, gelogy. and falloilt from atmosplierie neapons tests, etc., ac- ]iving habits. These data were flien coinbined f count for a DE less than.i mremfyr. with tho-e for internal extwure to yield a rinal The purtees of this study of narnral radiation estimate of total population do<e from natural expomre in the l~nited States were to better esti-smu ces. mate population do-e from nullation of natural The primary problem in usine the infonnation origin, to hnc-tigate the DE variations that re.-ulting from the AIO!S :.urveys was in con-occur, and to examine the pannnerers that intht-verting the count rate data taken at altiimle into ence both the levels and the variations so that the DE rate data at ground level. In a.blition, thett relative imtwnt:uice of in:nunade exposuru can uas the necessity in certain ea-es of mhtracting be 1(tter evaluated. In undertakine the-e ta-ks, the contribution of w eapons :c-tine fallout from it wa-recognized that esternal espo-ure to ter-the AIDIS readin:n. Suitah!c correction

• for this n~ trial radiation sources, a primary component.

latter fattor were made, and a conversion factor I of ilat'tt al background expu-u!V. van be e-timated for the AlO[S data was determined by corrr at-by diiver measurements or calculated on the basis ing the mea-uren.ents at a number of points with i f \\;NuI 1ge of rheluical assays o[ natural emita remlings maile at 3 feet above grmmd 'ewL The c !cr-in !he -oil. II! rect inc1-u t ofi:vM! $ and -oil .neatl telre-trial I!E. r3 !ainc { ott *be IcW < f $ uahsc<. Low ewr. have not teen -m iciently areas <un cye.1 mder the AIO!8 pu.ura u ud < sten-ive to provide adequate ilata to make an ue:ghted for the la>puhrion of each : ova. um .n erall e-timate of the population DE in the computed to be 14 num 'yr. This m!ne coinpared l'alted St ate =. For t he-e rea-on<. alternate meth-well with r. -91ts from limited ground -ur.eya 41 =- -. - - _ = 1

within the United States, which are summari:ed from natural external radiation was computed to in the text. be S4 mrem /yr. per person. Based on the 1060 On the basis of an analysis of the ARMS data, census, this results in an integrated DE of 15.1 } it appears that the United States can be divided million man-rem /yr. The range in DE in the into three distinct terrestrial radiation :ones, or United States is 40 to 300 mrem /yr.; however, j areas. One is the Atlantic and Gulf Coastal Plain, almost the entire population receives less than which includes all or portions of all States bor-170 mrem /yr. dering the Atlantic Ocean and Gulf of Mexico For the purpose of determining the DE to the from Texas to New Jersey. For this aren, the gonads and bone marrow, the intluence of hous-mean terrestrial DE was 00.S mrem /yr. The see-ing, biological shielding, and internal emitters ond area is a portion of the Colorado Front was also considered. A " housing factor" was Range, on the eastern slope of the Rocky Moun-computed to take into account the attenuation of tains, which yielded a mean terrestrial DE nte terrestrial radiatien due to building materials. i of 59.7 mrem /yr. Tlfis is somewhat as exr+ ted This factor included allowances. for the major i since this area (approximately 7,000 sqt. re types of building materials in use in the United g i miles) has crustal concentrations of natural States and for the percentage of total time spent radionuclides which have been shown to be ap-indoors by the popuhtion. Also included in the 2 proximately twice the U.S. aurage. The DE in calcuhtions was the attenuation of terrestrial the rest of the United States, that is. excluding radiation by body tissues. On the basis of these i the Coastal Phin and the Colorado Range, was considerations, the ratio of 'ndoor to outdoor DE calcuhted to be 45.6 mrem /yr. When the distri-from terrestrial sources was calculated to be 0.S; bution of the popuhtion in the three zones was coincidentally the biological " screening factor" considered, the mean terrestrial DE in the United was estimated to be 0.S. Allowing for these factors States was calcuhted to be 40 mrem /yr. and a DE from internally deposited radionu-A detni:ed analysis of the distribution of pg. clides of IS mrem /yr. to the gonads and 17 j uhtion with elevatier howed that 53 percent of mrem /yr. to the.wne marrow, the tctal gonadal l the people in the United States live i t areas with ar.d bor.e marrow DE for the U.S. population an elevation of less than 1.000 feet. Popuhted were calculated to be SS and 57 mrem /yr., I areas, however occur up to 10,500 feet. At ses respectively. kvel, the ioniaing and neutron components of It is to be neted that the gonadal DE as caleu-cosmic ndiation result in DE of 35 and 6 hted in this study is considerably lower than the mrem /yr. for a total of 41 urem/yr. The DE UNSCEAR worldwide estimate of 105 mrem /yr., increa<es to 44 mrem /yr. at 1,000 feet and nnges which is often cited in the United States as the t up to 100 mrem /yr. at 10.500 feet. On this' basis, " baseline" radiation 'evel against which manmade the DE from cosmic radiation for various popu-radiation sources are compared. If the results of brion groups in the United 5t:ites varies by a this study are true,it is quite probabie that cer-factor of 4. Overall, the calculations revealed that rain manmade sources, partieuhtly medical x ra-l the average DE from this source in the United diation, will now be given greater importance in i l Sutes was 44 mrem /yr. terms of their overall contribution to the popu-Combinine the DE from ter re-trial and cosmic htion's total dose. l l radiation, t$e aurage DE to th2 U.S. popub: ion I e l l l t 1 1 x _

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ils : 1 e

t i r ri I. . ami Gn&n. E.L t M : hem

ueasurements. 08AEt 70 se i

Dm1nnent II Aq,-- ;t. of the extwure of huma.t popularit.ns to environmental .ir.orne i ug ter 1ir i o a ni s

1. ? n d M. H. I. I M :

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11 - Rad!ation.Inantific, and units. R@ntt sine rue

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. '[, 1 14 f. a C"W9 EI""' CLb ' #"' !Il' UE' t l 4' g p ~ Propo-ol cal' mitYn fators for % f.a u ghlin. J. E. ' it'70 l

• Ap:. leat!"n yf aa uma ray a

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'U**: M8 #' i fh I i,

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Washington, D.C. 20402. 37:?M -005. i Pal. Y.t1N7): Co.mic rays and their interactions. (Sec. Solon. L. R. i 1NO) : Dosimetry of natural ionizing and elition. chat.ter 11. part Ol In llandbook of radiation. (Ph.D. Resis) New York (*:.irer>1ty. New Phystes. 3!tCraw.I!!!! Book Com New Wrk, N.Y. York. N.Y. Patte son. H. W Iless. W. N 3!w er. B. J., and Wa1 Solon. L. R Lowder. W. St. Shambon..L and n!sts. IL law. R. W. (1%3) : The !ux an ! slectrum of cosmic. (1000): Insesrigations of t:atural environmental radia. ray prm!niv4 neutrons as a fanction of altitude. IIealth. tion. Science 131:N3-906. Phys 2:60 72. Spiers. F. W. a 13*.0 4 : Rad!nattivity in man and his en. Pensko. J., 3tamont. K and Warda to. T. (IND) : rironment. Brit J Rad 20:409-417. 3fea>urements of to:Jzing radiation domes in duell. Stephens. L. D., Patterson. II. W. and Smith. A. R. Ings in Pohmd. Nukh+nika 14:115-424. t 1N1) : Fallout and natural background in the San Per3hagen. A. II. LIND) : Snow. iver in Sweden 1031 Francisco Bay area. IIealth Phys 4:007-274. LAO. Sveriges 3!cteorologiska., b !!ydrologiska Inst 1* Straub. C. P Carter. 3L W. and 3fneller. D. W. (IM) : tut. Communication Series A. No. 3-Environmental 1.chartor of unclear debris, J Sanitary Peterman. Z. E. t !N3) : Genchem! try of uranium and Engineering Divi.lon. A8CE. 00 No. 8A0 Proceedings 'hornim. I Unpubth b4 data). U.S. Geoh*;ical Surrey. Paper 4300. Detv.ut.cr. IN4. pp. 23-40. Wa.hington. D.C. T pton.1. Il and C"ok 01. J. t 1N3) : Trace elements In Phair. G..tnd Gottfried. D. (IN1) : The Colorado Frant human ris-ne. Part IL A.htit -ulderts from the L*nited Range. Coh.rndo. U.S.A. as a uranium and thorium Fiates. !!ealth Phys 0:103-143. province. In The Natural Radiation Environment. Uni. U.S. Census Bureau 41NO) : 1MO Census of IInusing. ver>ity of Chirngn Press. Chicago, lih pp. 7-05. V.dume L States and, mall areas. Part !. 7.S. sum. Peper n. P. e 1N4 ) : Aeroradioactivity wurrey and areal mary. Sugerintendent of Documents. U.S. Overnment grob.gy of parts of east. central New York and west. Pr:ntlug Od'ce. Washington. D.C. 00402. tentral New England ( AH318.!). USAEC Dorument U.S. Cer. sus Bureau (1963) : Paputation d!,tribution. CEN 59 4.14. urt an and rural. In the Calte.t States: 1900. 3f ap dE. Pg;e:me. P. 51Nda ) : Acroradioactivity $ntrer and areal .0. No.1. Fuper!ntendent af Dm umente. U.S. Govern. rat..ey of part, of wutheastern New Wrk and mouth. nwnt Printing 9:5ce. Washington. D.C. 09402. . ru New Png'and LA R318-1), USAEC Document r s. Crn>us Dorean i1N01 : Stat!stical Ab> tract af the CEN ~A 4.G. United Sta tes. Su;erintendent of Da"unent - '*. S. Pc;vnoe. P. i1NCtn : Aeroridioacthity curs ey and arest Gurtrmuent Printing Ocire. Washinginn. D C. ::vw2. gml..cy of the Denver area. Cob rado : All3!S-I). L*.S. Dep:trtment rf Housing and Urban Development 08 AEC D4 um. nt CEN rA4 *.'1 ilfcb : Annual stati>tici s umma ry-4 NS. Dvpa rt.

• L f t. P. D. La !*r. W. 31.. and Prek.1 L. e 1970) :

enent of !!ou.in; s d U&in NLpment. WWng. %. m m.sts..fs le ray !"niza.kn m the atmos. %n. D C. Ge logy a nap in !he Rre. Pe-nG.1 ' EC D+ tmrnt it.48L-204. C.8. Ge..b.6al S urer a :NO) : a R.u..! %.%lle i!Nin: IN1 Commerrint A !as and 3far. U.S. Ltional A!!as. U.8. Ge. ogical 8atts ey, Wa.hing. kotin. Giude. R.md 3teNall.r and Ca. C!dengo. Ilh ton. D.C. %binwn. J. P. an t Centerse. P. E. t1M) : Smr mary U.S. P :blie !!ealth Service 11ND) : Peruhition dose from 45

a X rays. U.S.10G4. INbitration No. 0001. Superintendent Wedepohl, K. H. Esce. Ed. (1969): Handbook of geo. of Dinun ents. U.S. Government Printing Office. Wash. chernistry. Springer Verlag. Ber!!a. Ington. D.C. :;0402. Weng. P. S. and IInang. C. Y. (1070): Background U.S. I'ublic Ilea!!h Settice (1970): Radiological Health activity of Taiwan. Presentation at fifteenth annual. !!aadbook (Iterised eitition). Suterintendent of Doco. rweing of the IIcelth Physics Society. Chicago. Illi. ments. U.S. Government Printing otEce. Washington, nols. June 0$-July 2.1970. D C. : 0402. Wesley, J. P. (1000) : Background radiation as the cause UN8CEAR (IN2): Report of the United Nations Scien. of fatal congenital malformation. Int J Rad Blot j tiac Committee on the Efects of Atomic Radiation. 2:07-118. I Sevente-nth ses*lon. Supplement No. 16 ( A/5 16). Wo!!enterg H. A., Patterson. H. W., Smith. A. R., and United Nations. New York. N.Y. Stephens. L. D. (1!W)) : Natural and fallout radio. }* UNSCEAR (IN4): Report of the United Nations Scien. artirity in the San Francisco Bay area. Destth Phys tine Committee on the E2ects of Atomic Radiation. 17:313 321. Supt ement No. 14 ( A/7.514). Yamagata. N. and !wa=hima K. (1967): Terrestrial d ) Nineteenth session. ' United Nations. New York. N.Y. background radiation in Japan. Health Phys 13:1145-l'N8CEAR (1:aQ : Retert of the t'nited Nations Scien. 1143. tine Committee on the E3cets of Atuale Radiation. Yeates. D. B., Goldin. A. S., and 3foclier. D. W. (1370) : Tw enty.Srst ses. ion. Supplement No. 14 ( A/6314). Radiatirm from natural sources in the urban enviroe. United Nattens. New Yo i. N.Y.

nent. Report No. Il5PII/E!!S-TO-2. Dept. of Earl.

(*pton. A. C. t 1:61) : Radiobiological a> ects of the runmental IIealth Sciences. IIarrard School of Public supersonic transport. A report of the ICRP tok group IIcalth. on the Idoloirical effects of hig5+nergy r.dlations. Yeates. D. B., Goldin. A. S., and 3foeller. D. W. (1972) : Ilealth I'hys 10:003-006. Radiation from natural sources in the urban environ. Watt. D. E. L INT) : Dose eluivalent rate from cosmic

nent (to be published in Nuclear Safety).

ray neutrons. IIentth Phys 13: A)1-007. l i i l I t .h 3 'n -wwy- -w r- -mv-

i i + 4 1 APPENDIX A \\ tv l.Sr,p/ 4 c t d' h Calculation of Average Dose Esguivalents \\ / 7 ilite to Terrestrial anil Cosmic Ilailiation ' 4/ [O V,-is 'f a ,rj I-rg <(/ cv,.y $ a is V Tabie.\\-1. Calculation of average dose equivalents due to terrestrial and cosmic radiation by State urban-ized and unurbanized areas Table.\\ 2. Total calculation of average dose equivalents due to terrestrial and cosmic radiation by States Table.\\ :t Prngr.n to calculate average dose equivalents from terrestrial and cosmic radiation i l ' 9. :;e..f t he vainc< in the f. lb m h;,; *aMeg are -rc--..itr-d in 'etc ha *>f a reta yr. Th!* wa* 1..ne In nr.lcr to avoid reninilim:. ! errors. ::ral. ne -h. +111 t.t. --ti:ae that the data a re kriow n *0 the ;or*zr:tt,r ir:dicah d ;iy j the uttuit.crs. 49 C-I

I ~ 1 \\ 6 I o I e G N a 8 . =1 3 t, 6 I o r. e, e, e eew ,.e-c,ee e% 4 e 4e <e 4 e., # %. -e e 7 e e c. e e, rg e e c s ~ e ce "3

e.. a.

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1.sservant ts% a?s? ett%7 e

1. * * = ; t ' N p J

154 "68 ( l '.M 3 = s.' Amort *wsa r e t t ai t..tg i3.* q.s e a s it. 3 3s a3 3 4.st. a.= 3 t air...p t j its 096* ttr=6 e. 's 154 1a90 c%nt.. 'e<(.2.?*t27* ser e.. i. 3 s s t s gn. g s( e 6.o.i;e j r q a.c(.es e lf ge s. 61

• ~

~ ~ - -. - -. - - """"**-p he e g

Table A-3. Prograrn to calculate average dose equivalents fra terrestrial and cosmic radiatios-Continued i t ,e, ,,et r y o v,, r 3._, f., s. f *

• i 15% e,s>

r,s-. . ciew$.r,ofi i.r s t$v mesi ratre.

i. f 5we I

15% 3:46 nen.cf$ra.rno$n 154.Tage tretfq.co.1te.9 tm 12n 159 304F ]C I T n. C 1. ? V.O 'A 18.0 ftw case wet 15% 30A0 1c

• 0 is)*.?Ft,4 1%9 igt 18 t r - 960.50 90

'~ l 15% 30g2 Si * = Ne e 1%4 CS$1

• n ("%ft..s 15N.' s% 6 14fEavist.,wissvg%) acain 154 349 As aNoe1cae amoit 151
• g*

aNas*. ages".6%e t%4 3s7 C ?tve=.cr$vo w r9tva ee*per 154 ^She '7C5r iTL35 w.To'.%neeney s les r;ge 9tqf9fu'rlfqfensi 1$N (170 ' 7r$ i Jl s ?'S tsN 0)?1 af9tJlstSO%e l5% CQ77 aritJIsf.C$v4 !$N C177 %se=tgcftffestse=tt$f4ffler(Deenm) l%% '37A % T A Por t l $7 4 t F, =% T a708 t lif t t().aney !$1 1074 88 L 8vi t %f ai r l s D8(C V i l st at e),3qogest y y 1 90 4 sesyr*6l51A'FinarNyT6415 aftleaqoyerssis 15% 'iN 09ff ar t Ns s t e r st ss eettF16sts?gfri.onsoort:Ns 154 v7A i'.s=sii ritemissa615 a! Flea %a ISN r3fe (*s9tl$raftleic89t!$?titlers9eappet LS% Aia0 2 7 00 5 tTSTA T El e a f 30 59 t l %I aI E l.7079 10156 e 15M Scot gc 9gve l t $f airl s'a$ve *098U.$Ca$va t t $f att) 154 (*e* 13

• =proep..%

i 'tg ecet 'sNe e sNae.* 1..% lis (;a6 La .,(s'..e TSN sram tett : ev..% isv ri4A .TT7 tT,. TTra s t,y a t. J ). g.t..i. s a a. I Et e,L a.r su r..r t es. r e5 v e, t aa$n i 'im.I1%s 154.118 T 10 TO 20 t%N cite 71 Irt1Sof*d.80.tl*n 79 40 15N (.2 a 0 15=fCast i 15% imot t =0t p.1 % f a t? 1%4 r022 i' T3 43 tsw ;cos em t t uite iw f )16 2'o9=1.150 t$N m*ga [ c g 3 f a3 9 3 t 13,

• f. 9.1319'J a t f tr ap t f l

.iN u li7 Ad?# e i !$4 '094 18t%f10'Dtil.%?.?.itD'98899V6.9 1%M 1130 l'tf*PGtfv(18/007U*.$ e 1%4 Stil r49f es p* NitT 6 f t t / O"Dy '." TIN==8fi N6stt/Jo*U 119 JL*2 r $ v t e t'.9 5 v a t t t / pe pet l$N 11 1% tin 9104 I;2$1s f3Gi'lla/*'99 ftN *t 39 '80 5***ltl#3*py it% J f36

ssa.casalgi.. jot..g

.tv 1;0? t. Ite.t.atff s i s ~ ~ ~ ~ ~ w y .v---w- ,wvi -ww ..-,w+,-y-m yyw e,-w-,---------,--w---

( 9 Program to calculate average dose equivalents froin terrestrial and cosmic radiation-Continued Table A-3. i e t re t a. 33ei v s v a t e e f. =i..t. 3 9. t eo. t e t e.t t re t i. c* rs.c t rws. cat ve. es, aise w t icosa.;eo.zasa 154 Once twetost$rafp 15 4 Otto Ga. 10 30 Itw Slit si we' f t t a. 200 3 ~1)O !=1 91 154 otti 01 ft1 $lt* sae*J t.0%0 t e t t'470p t t i..f.o. s ac ey es f Apos t 3 i ist 1116 154 0116 toCo = 0 ft1 014 F (F4Sfaeletti.T'.3.lto^peagege g 114 Otto Islameftpwetitea*Ue.4 15% 0120 (*4uf6**CNuT64191008u 154 St21 r i sqs. or,1 cq6 tissaen 151 at27

15f 4 = >C 35,a t g a f saag 154 0124 716tc ofS0$ Cit 1/8asy 154 0126 CE N = 51Elt l l t o'ou 11NestaNettI*.00te.5

($4 012% =a g r g t., a t o s t g r a f s t t. J g.J e g,3 p g ana, tg g g,g a r e g 3,csu r ,( t rws.t r$ve, 15% C126 111 t f 30$P."Jf i. i aNG 454 0127 =41Tfth.4L19 15% St3R tt%esa% ecee.imte.s 154 3.79 Ftf =F L *' a %# I0 f one f54 3110 C a s v e e r.m t v e u s tor pas 15N Stil Gs11,r.sNa ge f T.)T ano f19 't17 c%Cet0050* stare,* =d!!Et'.41lafL;.. M'8.filtC oti!Of.1414 ii% 31 )) 154 ?t}6 .alfFla gett 159 11.15 t=36 ~~ (*N OttA t=0 lt w Jtt7 .aiTEla,+62t!.t.ggtsevels tsw ?tta

• t **

15% O t s' +3 140 L*)ie271.% 1%N 1160 Jet *6 154 1161 sal-t t$M 3167 Late 6 (54 3. t 1&ll.G;.764tJ=i*e eelfFtA.2079t.J.INicavts) tt4 116 ~~~ L14 siNILNys 154 3164 144 ?l67 eetitle.eoglintoep !5% ?a=8 Sr00 1(N atee 121 no 170 e.1,76

s% at<0 t..

Is% ot*1 161 % e. a wl S f t t C '$ve 15% 045' N=1 15% 0151 90 140 f=3*.271 5 .tw 31** IF(%*-19163,45a.140 104 2155 141 %=4+1 154 3196 L ei C 3%Il%uf t$g ?tg7 t%tr e w t gl e t % f f s V t Ml e t e rstf l u t estmJ)

i% ;158 173 C

%TL%u6 lig~Otse e.n te 55 ii% 'is0 113 10 220 **d1.186 ISM 2144 t.*-40

't *, .__ =_____ _

~ ~ f' t i s I: lo i; Table A-3. Program to calculate aversge dose equivalents from terrestrial and cosmic radiation-Continued i U .c4 N.. ..,.._i.r s. 15% 21st %.t l tt% *166 y t3 !*14.??f.4 15% 0165 18 6%*-16210.203 203 .t% 31** 703 %.%.I i ~ "lTN 013F 713 ( 3Nt ( *.uf tt% *tga

% *ra vig t.1 %t es v IN g. e osar t t u t ea*eir e t w

tie 223 c s t t eus

• ?% 3t73 C*

' *, e t T$i ?t71 43a s. a. a r u t z i. u.. s s. ". z i. ; f. 5 s.12. - a. i t * *. I. 2 s t. $ s. 8 +. t. * *. 8 +. t. '!t.t16##I ' ~ ~~il % Ol'2 2T: s 'av aT t i g t.11 s. gan g $ rs g et,f t f*g 0, F O'exafl0% v5.JMs 80ul v aL8%f. 1//&9t.7?*T?tst if t es,o .

• 4
• v. 5 0== =8 8
• 1/ v e Ye'tt a r t eN # p t is%

't') 407 scaeafts?t.16 2a. 16..s.886 .'t 7 6 401 s a tw at t l et.21s. 2;wfit at 8'P JL a f I CM. .St2.31

\\% 0D5 3% s's=arte4246.at.12pl j

!t%

• 1 te oca sa==af fire,3,ses.?g t W 1Tt'

.c4 s 'e = a r e 14 6. D. l '. s a, 3. r, c.s. 7. g t.p g. g l s i= oct c ae= at e t.i. i s e.i wi. t i v. t = >. t at.t wi. o r.1=*. si. t s-c at= t e s aa v a t t o= a a l'.11s. H 4.Lte,'ee.F.e.43,&}*13 1ft26s.001.#.14 elSt.d-LCCat(CN.Ps. l 7 sw t os a. s s. t a =8t avaff*N *actaf.9t.sw.ag gfve.gst.gangste Onts sg ir at gav 39 -s N-a t. i. t 7 's. t a =ent s al l:%. *..<n s t.+ s.. < 4 Aga.. s. I.e s.

• s. I ws. t v. ta'. 8. e. e s. * * = e r e t / v e. m t. e.we r e g f, e. f t.e.egt.

s --Nsur.Is.4=l'%..a..wr rst,fg it%

,s sea r-ewtittw. t ! v. i t. 11. ? v. ' *. ; t. i t. a r. t ?. s t.1 s E *. t. Z r t.

• f. r '. t.
• t.

t '*.1.'s.4136 it% aga7 ces s a a m a r i t 41. t e s.t wt.17 e. t = 7. t e r.1 wi. s v. t wo..v. t **C a* *l e s ae t a's 7% n r. ? v.1* *.11 a. 5* 3 7 8 5 s. 6 2

• 6 S e e 2 7 a s e. ? 11. #.1.

.1=s.**.5fars es. ? &=tano.6r.t*=<trvart 4 v4Glar.*t.e=*efu= tar!W la**.Hf' 6u '<EG $rre.1)r.t=*'Ese Satt so ~~~ ~ ~~ 7 '7f4L Jar ^8

• a%-48*.i.14./'s.t'.27 s%s..v.gaa.er.twa.*v.*wt.a.a.sv.gwestet/ve,gs,a es s.g f w e, s. t w

.ess, -.% !. a s. t a l %. e. 'a i l at. / t ft% Ol e t St 3 8 4 = 4?t 1= . ? ? t.t t s.. t. v e. 't. l a. a g, g y,6 g,3 g s g, g,7 g g. g g, s., g, e r, p a, t t.Ti.1:truction. Masonry '""*"*I "IS * "**dI 4'onnt f r the bal-

i. From table 16, it can Le seen that the ratio of the indoor to outdoor DE for wood fr:une ance f singic homes. It -hould be noted that houses rances from 70 percent (Lowder and the MA designation of frame Lon3es refers Condon 155) to 32 percent (Yeates et al..

to the method of roof support, and apionxi-1970). mately one third of all frame homes have rome Similar ratios for homes of masonry c mnrue-brick or stone facing. The other 25 percent of tion range from about 72 pment (Oh!,en, the U.S. population is asumed to be.lisided IND) to 100 percent (Ohlsen,1960, and Yeates qually between living.in frame and ma-onry et al.,1970). Based on an analysis of these du eMings. data, it has been assumed for purposes of this

3. Sixty-eight percent of the U.S. population nudv that the h. side to outside DE for frune (U.S. Census Burein (IND) for ING) :s as-Lou [es is 70 nei unt and for masourv houses is F"ned to be engaged in away.fremiome activ-

~ 100 percent. ity (school and work) for 40 hours week. or

2. Ses entv-five nercent of the U.S. population is di percent of the time. This time :s asumed assumeil to Nve in one.familv homes, based t be spent in buildines which are 50 percent frame and 50 ent masonry. The n"nainine upon U.S. Census Burean (IN5) estimates that l

76.3 percent of all housing units are sing'e' 02 percent of the r, pu'ation :s as-mned to be homes and that the mean number of occunants at home. per household does not varv significantl'r ac.

1. Ninety.five percent of an in.lividuars time 14

~ cording to -ine!e or multihousine unit status. '8'umed to be spent indoors. This vaine is Durine INi to INS, data collecte71 Lv the Fed. 1 cued on a runey by I;obin-on and Conver-e ~ eral IfAusine.\\dmini-tration (FII A) on finane-l1N6), in which they rumu uia the nays d ing new ami cd-tine homes # U.S. Dep utment di:ferent catecorien in which people,pe n.1 l of musine and Urban Development, IND) their time. Only tuo tegories an be c'<.u ly ~ "I as,We art egtM en h mii -h.*Aed t}lat the pro {' ort!Un o[ frutte houses ( -oid in the United States ranced from 7.3.0 r er-uHking) and these account for 0.1 h are day. .\\ithough FII A tin.ubed Laure ac*ivities ac-onnt fo r !.1 ' a i -.iay: I s ent to 32.2 per cut. Je - - " ed t o be..u t. -i es .u u r f. u only a m. :ority of '., ne M. " vnt "f this I 'e. :Les ;e; re-ent the m.'y data a. "' A'e on L.rm mUne a vr :! of L2

• i - tiay.1 !*r.

'If 'N 'h ! On. On the l i -:.4 a n[ 'here -:st ). .L M ;h t d e t !".;e '.'i oh Wi d ?! pi re 6 d.lt a. it 'i !* I tytt i -t 1 lated for purpo-03 'sf this -. Led 'o ! e ; door.h l[\\ it;es v >r t he purpil-e c5 1 l l t _:-===-.= l l L

1 P I of this =tudy..\\utomnbiles provide an attenus-where i tion of 0.77 (indoor / outdoor terrestrial DE) (Solon et al.,1060), whh h is similar to that of Pm proportion of population at home dwellings. Other modes of transportation are (0.32), also asmmed to similarly reduce the terrestrial he - proportion of population living in DE..in error may be introd, teed by assuming frame dwellings [(0.75 x 0.8) + that all work is done indoors. We must keep in (0.25 x 0.5) - 0.73], mind that many kinds of work are " outdoor Sr - frame attenuation (0.70), occupations. Or$ the other hand, much of the t, - proportion of time spent indoon l work in outdoor occupations, such as police and (0.95), Sre duty, transportation, and construction, take

h. - proportion of population living in ma-place under cov r.

sonry dwellings (1 - h, = 0.97), l S. - masonry attenuation (1.0), Based on these : sumptions, it is possible to pi - proportion of population working or I estimate a " housing factor," which is the average attending school (0. TIS),

f. ctor by which indoor living reduces man's ex-

d. - proportion of time spent by workers

,. -ure to natural sources. The expirssion for and students at home (1 - d, - 0.76), ic:er.. ming the housing factor (IIF) is as We - proportion of workers and students in E *3: frame dwellings (0.50), Ito:ne populatica d, - proportion of time spent at work 3 IIF = p.[(hrSet ) + (h.S.t )] (0.01), i i 2 Sshool and ! abor .= propodon of woden and Mmkn!S in

epniatica at ho:ne masonrv dwellines (1 - W, - 0.50),

~ pi[(he8:t d ) + (hmSo it ds)] and ~ i School 1milabor t, = pioportion of time spent outdoors (l - popiation at urk ti = 0.05). " Pi[(W,S,t d.) + (W Sot;d.)] i ' ((,',*j, The housing factor is found to be 0.30, when the j + ( p + pi) t. ( B-1) above values are sub<tituted in eq. (B-1). 4 0 1 _.__ __,_ x I

e (.. APPENDLX C Calculation of Sr Error of Total Dose Equivalent For the purpose of calculating an estimate of Wos - ([(0.64)(16)]' + [(32)(0.32)]' the errors associated with the overall DE esti- + [(32)(0.16)]' + (11)* mate, the method suggested by Kline and McClin- + (10) * ) ' ' (101.S6 + 101.$6 + 26.21 tock (1953) has been used. The overall DE is calculated by + 121 + 100) ( 456'03) = DE - X,X.X. + X. + X., (C-1) ,1.1, or doos - 10... mremiyr. =. u-here It is interesting to note the relative contribu-tions to the error variance of the overall estimate: Xi - terrestrial DE, X, - housing factor, Relative X, gonadal screening factor, Parameter centribution X. - cosmic ray DE, and X, - terrestrial DE 4 X - internal emitter DE. X, - housing factor 4 The est mate of the =2a range may then be cal-X, - g nadal sercening factor 1 X. - ecsmic ray DE 5 eulated by the following equation: X, - internal emitter DE 4 For further improvement in the total error, it 2DE g, gE, g, i Wog + eX, would appear most useful to improve est: mates ( 2X, j of X,, Xi, X:, and X, in that order. Relatis ely i /' 2D E little would be pined in :iceuracy by :aprov-i' ..+ M. (C-2) ing X,. Table C-1. Eratuation of partial derivatives in error ' *!' "t ' ' f"" a re ririmeter r.irtist Jerh attre W, W:,.. W. = uncertainty (20s) inter mc = -((," xi vals of par. meters xi ) X, X:,.. X, and Was = the =2a interval = x.x.:n = 0 91% 2 3 mn of the total DE. ,, n c,

x, x,

4x. "'2** = * ** = T1.e s abes for el e me ms md 05 perecat confi-m n = Y[,"- : L ', ce mierval at..ates may thea '..e -ub.ituted x. = xmn - nn

n eq. iC-1) (pntial deris ati es are calcu!ated we = f[E- :n in table C-1). Lte that the pioeedure '--umes n

,that the i ar uncters are independent of each - i n,, x, L mE = 2"- = :n ,6 r. T'.ms, E - _ _ _ _,}}