DISCUSSION
Dn. FARR: Will you comment on the
Windscale incident in terms of the monitor-ing failure?
DR. HIGINBOTHAM: I think Dr. Eisenbud
is better prepared to answer that question.
DR. EI5ENBuD: The Windscale accident
frequently referred to was a classical, but unique, episode. Windscale is a plutonium
production center for the United Kingdom
Atomic Energy Authority, similar to
Han-ford here in the United States where the
United States makes plutonium. The
Wind-scale reactor in question was probably very
efficient for plutonium production. For a
plutonium producing reactor, efficiency in
production is one design criteria which
differs considerably from that of a power
reactor.
For example, for fuel, they use metallic
uranium, a pyrophoric fuel, whereas, a
power reactor usually is fueled with
urani-um oxide. The moderator was carbon and
the coolant was air. So you had air, carbon,
and metallic uranium-a combustible
mix-ture. It is known that in the fission process heat is generated which must be dissipated. Failure in this regard leads to the graphite catching fire. This resulted from an instru-ment failure for the core of the reactor was
not instrumented in such a way that fire
could be immediately detected. This was a
deficiency in design that became obvious as
the details of the accident became known.
The monitor placed downwind of the stack
to collect air samples did function and by
this means malfunction at the reactor was
detected ultimately. Upon examination, the
core of the reactor was found to be on fire.
It presumably burned for several days and
over this time released iodine from the
reactor.
The significant thing, which lead to a
radical reorientation of thinking in
acci-dents of this type, was that there were
es-sentially no nuclides released other than
iodin&3’ and some of the noble gases.
Strangely, strontium9#{176} remained behind;
consequently, the terrain downwind of the
reactor was contaminated only with iodine.
There resulted a great mobilization of
resources in England to deal with this
prob-lem. Though there were some people
ex-posed to higher doses than desirable, the
highest dose received by any child in the
area was about 16 rads, which is below
some doses from weapons testing fallout in
this country. Except for the fact that the
core wasn’t instrumented properly, which
was an engineering failure pointed out by
the British themselves, the monitoring sys-tem did work and the mobilization of talent
to deal with this emergency was quite
ade-quate. However, the loss of a major reactor was a very costly one, probably in the mil-lions of dollars. Yet, the total cost of the
milk that had to be confiscated in order to
deal with health hazards stemming from
this incident was only of the order of
$50,000.
DR. HIGINBOTHAM: I would like to say a
few words about reliability of monitors. As
I tried to explain, there are many types of
detectors which can be put into all kinds of instruments. As more experience is gained
the quality of these instruments is
im-proved. The development of the transistor has made a great difference in this field for it is considerably more reliable than
vacu-um tubes. It seems to me there are cases
where one has not anticipated these
require-ments and I would think these problems
arose perhaps a great deal more often
dur-ing the war when the Manhattan project
was hastily assembled and a very fast
mov-ing organization than they have since then. It is possible to do a fabulous job of mea-surement and control. The evidence for this is that reactors do indeed work. Reactor
op-erations depend on very precise
measure-ments of radiation and rate of change of
radiation. The instrument must be extreme-ly reliable. The development of radiation
detection, monitoring devices, and
mea-suring instruments for reactors has been
manu-202
script, I inquired of many friends in health
physics about their experiences with
moni-toring instrument failure. There are not too
many cases where the instruments
them-selves failed. I can think of none. All of the
accidents I know stemmed from misuse or
carelessness.
Dii. CHAJIU?.s: Speaking of mishaps and
failures of monitoring systems, would Dr.
Higinbotham comment on the difficulties of
the American authorities in locating the
bomb lost off the Coast of Spain?
DR. HIGINBOTHAM: Fortunately, that is
not essentially a monitoring problem. This
incident is not in my opinion one which
poses a real hazard to people. It is rather a problem of maintaining secrecy of weapons design.
DR. MENEELY: Biologically, retrospective
monitoring can also be carried out. An
ex-ample of this type of monitoring is the
sur-vey of deciduous teeth which has been done
most extensively in St. Louis. Dr. Harold Rosenthal will briefly relate experiences with this type of monitoring.
DR. ROSENTHAL: It became apparent
early in the atomic era that alkaline earth
nuclides, and other “bone seekers,” might
present a potential hazard to biological
sys-tems. Altllough some random studies of
strontium9#{176} content in milk, water, various environmental systems, and the atmosphere
were performed prior to 1954, the need for
knowledge concerning the body and
skele-tal burden of strontium9#{176} in children and adults prompted the initiation of concerted efforts to determine strontium1#{176} levels in
calcified tissues and to determine any
differences between strontium and calcium
metabolism. Subsequently, the U.S. Atomic
Energy Commission established a Health
and Safety Laboratory for the prime
pur-pose of monitoring the strontium9#{176} levels in
the atmosphere and environment, in milk
and diet, in bone, and in many other
di-verse ecologic systems. More recently, the
program for monitoring of milk has been
expanded throughout the country by the
U.S. Public Health Service.
The complexity of bone metabolism with
attendant variables of localized ossification
centers, appreciable turnover rates,
ex-change, and accretion are further
compli-cated by the discrimination of strontium
relative to that of calcium. The idea to use
deciduous and other human teeth was
sug-gested initially by Kalckar and was based
on assumptions which would eliminate
some of the variables present in bone
studies.’ The assumptions were:
1. Large numbers of deciduous teeth,
normally shed by children, could be made
available for scientific study. The dietary
history of the mother during pregnancy and
the history of the child during infancy and
child development would be well
docu-mented.
2. The crown of the tooth, once calcified, represents a stable structure in which rates
of turnover, exchange, remodeling, and
ac-cretion are minimal or absent. With this as-sumption, the strontium9#{176} content of the
teeth represents an equilibrium between
calcified structures and the diet at the time the crown of the tooth is calcified. Admit-tedly, these data represent the incorpora-tion of strontium9#{176} some 5 to 8 years prior to natural exfoliation and are not useful for immediate monitoring purposes.
3. Studies of the strontium#{176}#{176}content of
teeth would be of value historically and
scientifically by thoroughly documenting an
artificially created, hazardous condition which would, hopefully, never occur again.
4. Infants and young children
ac-cumulate larger amounts of mineral
ele-ments in normally developing bone and
they may be more sensitive to the effects of radiation than adults.
During 1958-1959, the “Baby Tooth
Sur-vey” was initiated with the prime function to collect deciduous teeth from the
commu-nity at large, to study the accumulation of
strontium9#{176} in the teeth, and to correlate
these data with dietary and milk fallout
strontium90. This study is being performed as a collaborative venture between the
den-tal schools of Washington University and
St. Louis University and with the collabora-tion of the Greater St. Louis Committee for
Nuclear Information. Although KuIp and
No. MC
L
Motkse li,.d A,iog test ste ma,ths ofps,.otcy I,:
Permtt
T.tephoos
Addr.ss Childs r.sidono. doring ths first year:
Mooths onfosos,: Ki,d ofmilk used in
Months ontornulo t 0th., milk usad fi,at yoo:
t.cisoe Cospid
stmel., 2’d nols,
Ceriass Rss,erad Root
Nen.oeriass Ho,.atorod Roetksss
#{149}A #{149}YStrossolos 90 Is a rad.iuactl,e nateri.l a fallout
T 0 0 T H #{176}I
z;
S U B V E ‘ aodte.thotchlldoes.
Will ysu hslp us eslIset 50,000 baby t..th a ysat?
The teeth you oemd mill be acalyted for strootiom 90 cooteot so Stat mora may be Irorned about the accunulatloo ofthis radicactise subst.ccr to the homes body. Slccr trOth must ha pooledto pro’Ide ecoots
material for each analysis, so reports cc lodloidoal
thn,,lrrs:tht erebtos:
oorequest. (tsP5)
Please sd baby teeth from childre,s of.11 aaesao d
onmamy teeth aspossible from each child. jf
Ss. a #{149}..th- a butts.
Wrap tuoth mall OPERATION TOOTH
coutosa.d attach BOX 222
ST. LOUIS S. MISSOURI
FIG. 16. Front and back of tooth collection forms distributed to interested persons with the kinds of
data requested. SUPPLEMENT
ii,. BABY TOOTH SURVEY is.poooo..d by tho (boat., St. Loss. Qugesa’
Coslto.a for Nacloar Isfoesatfo. I. coop.r.tloa mith th. School. ofD.otistry
.t St. Lost. sod Waobiagto. tJsl,orslti.o. ii,. otoney is .sppo,t.d by #{149} trots th. U.S. Poblic H..lth Scent...
For forth., hsfor,oatio. coIl or COMUITTtt -os NUCIfAS INF050ATION
5144 DoUse, SoaI..cd. St.Lo,i.. M,so,,i 6310$ Ph.,. PC 70500
INSTRUCTIONS FOR SENDING TEETH
Fill in both sides of thetop section ofthis cord. Fold cord sothat tooth isinside, put in anenve lop.,
mark hand cancel’ and sand to:
unwarranted objections concerning the
Baby Tooth Survey, the data accumulated during the past 7 years has established the validity of this study.’ The data obtained
by the Baby Tooth Survey has stimulated
the formation of similar study groups in
Canada, Great Britain, Denmark, Germany,
Japan, and Russia, to name a few.
The Baby Tooth Survey is primarily
con-cerned with informing public and private
schools, civic groups, and the news media
concerning the need for maintaining the
study by donating the deciduous teeth of
children. It is very gratifying to find that the St. Louis community at large is volun-tarily contributing 30,000 teeth yearly with more than 200,000 teeth already collected.
The donated teeth, accompanied by a data
card (Fig. 16), are given a number, the
cards are checked for completeness of
in-formation, and the teeth are classified by
dental students. Tilese teeth then become available for analysis of strontium90 content
by methods that have been adequately
de-scribed in detail.36
Because the collection of teeth was
begun in 1958-1959, many of the teeth shed
during that year represent the
accumula-tion of strontium in children born before
1950-1951-a time when strontium’0 was
just beginning to be injected into
atmo-spheric fallout and milk in any meaningful
amount. For second molars, which are shed
when children are 8 to 12 years of age, it
was possible to go back as early as 1947. As shown in Fig. 17, the strontium#{176}#{176}content in
deciduous tooth crowns of children born
prior to 1950 averages about 0.15 pCi Sr90/
gram calcium and the level increases
con-tinually until 1958 when values of 4.7 pCi
Sr90/gram calcium are reached. The
in-creased tooth strontium90 corresponds to
increased levels of Sr9#{176}in milk and diets.
Current information indicates that peak
fallout occurred in late 1963, when milk
strontium levels of 38 pCi Sr/gram
calci-tim were observed in St. Louis7 and the lev-els have since been dropping slowly. Tile teeth of children born during 1963 will not he available for analysis until 1968 to 1970,
and it will be necessary to continue the
Baby Tooth Survey until that time in order
to obtain a complete record-assuming that
no other fallout problems arise.
A theoretical expression for the Sr90/gram
C-,
-J C-,
E
C.)
C)
C,, =
I-TABLE I
FRAcTIoN OF TOOTH CALCIUM DEPOSITED DURING
I)EcIDuous CROWN DEVELOPMENT
BIRTH YEAR
FIG. 17. Strontium90 content of deciduous teeth as
a function of the birth year of the child. Each point represents average values obtained for 6 to 21
pooled samples.
expansion of the basic equation of Reiss:8
(Equation 1)
C, = X prenatal Sr90/gm Ca +
Y postnatal Sr90/gm Ca.
The factors X and Y represent the
frac-tion of tooth crown calcium deposited
dur-ing the pre- and postnatal periods,
respec-tively. These factors vary with the kind of
tooth and have been experimentally
deter-mined (Table I).
For bottle fed children* equation 1
be-comes:
#{176}The equation is developed for bottle fed in-fants because in this instance the calcium content
and strontium content can be readily measured.
If the strontium90 content of human milk were
simi-larly measured by as similar equation for
breast-fed infants could be validated. Dr. Rosenthal be-lieves the equation is valid for each group though the factor of 1.2 would not apply to the breast fed group. This also must be determined. Editor
(Equation 2)
C, = (x) 1.2 Cdtm D + (y) Cd’ D,
where C, is tooth Sr90/gm calcium, Cdm 5
the mother’s dietary intake of Sr”#{176}/gram
calcium from milk and the total Sr90/gram
calcium in the American diet is
approxi-mately 1.2 times the amount of Sr’/gram
calcium found in milk,9 D, is the
dis-crimination factor against Sr9#{176}between the
mother’s dietary intake and her fetus, Cd’
is the infant’s milk intake of Sr90/gram cal-cium and D, is the infant’s discrimination
factor against Sr9#{176}between dietary intake and bone.
In order to solve the second equation
given, values for D0, and D1 must be
ex-perimentally determined. A discrimination factor of 0.13 for D appears reasonable4’8
and a factor of 0.8 for D, has been selected
as an intermediate value on the basis that
children tinder 60 days of age do not
dis-criminate against Sr9#{176}10 and Sr#{176}#{176}
discrimi-nation in children under 1 year of age is
probably less than 0.5.11 Because the
decid-uous crowns develop and calcify in less
than 1 year, the 5r90/gram calcium in milk
(Cdm and Cd’) may be averaged for yearly
intervals and, with the discrimination
esti-mates, equation 2 may be solved to
be-come:
C = K Cd
(Equation 3)
where C, and Cd are the Sr90/gm calcium
for tooth crown and bottle milk
respec-tively and K is a constant. Tile validity of
equation 3 is shown in Figure 18 where
the determined values of Sr90/gm calcium
Tooth Prenatal (X) Postnatal (1)
Incisor 0. 0.68
Cuspids 0.06 0.94
First molar 0.17 0.83
evolve large expenditures of human effort
in order to obtain adequate postmortem
samples. Because bone samples from
chil-dren are limited, the skeletal bone studies emphasize the metabolism of Sr9#{176}in adult
or aged persons while the Baby Tooth
Sur-vey is concerned primarily with young,
growing infants. It will be in the current young population and in future generations where the possible effects of Sr90, if any, will be observed. Regardless of these objec-tions, it is self-evident that a thorough knowledge of the body burden of Sr9#{176}in calcified tissues is imperative for tile entire
life cycle of man from conception and
birth to old age.
The ever present danger of further
con-tamination of this planet with bone seeking
in various teeth of bottle-fed, St. Louis
children born during 1950 to 1958 are
plotted against the milk nuclide
concentra-tion. Although the determined values
corn-pare favorably with the lines drawn from
equation 3, for periods of increasing fall out, the validity of the equation for periods of decreasing fallout must wait until chil-dren born after 1964 shed their teeth
some-time after 1969. An extrapolation of the
equations for children born in St. Louis
during the last half of 1963, when the aver-age milk levels reached about 30 pCi Sr90/gm
calcium, predicts tooth levels of about 20
pCi Sr#{176}#{176}/gmcalcium.
The concentration of Sr9#{176}in the crowns of deciduous teeth represents the maximum amount of Sr9#{176}deposited in calcified tis-sues since variables of turnover rates,
re-modeling, and exchange are essentially
ab-sent. In contrast to teeth, bone turnover
rates that vary with the kind of bone are
appreciable, and the relationship between hone Sr’#{176}and milk or diet Sr9#{176}2,12 is much
more complex than that present for tooth
development. A comparison between the
Sr90/gm calcium in deciduous teeth (2.1 pCi
Sr90/gmCa) with that of bone (1.8 pCi
Sr90/gm Ca) for 0 to 4-year-old children
born during 1956 reflects the similarity be-tween the two calcified structures, although bone values e slightly lower, presumably due to appreciable bone turnover rates.5
Because it is necessary to determine the
relationship between dietary Sr90 and the
to a bettersues,augmentdepositionthe eachtoothunderstandingof theother,studynuclideandand of theboththein bonecalcifiedstudiesunderlyingstudieslead
tis-principles governing the metabolism of
calcified tissues. However, neither study is
I I I I I I I I
Inciso, Sound 0 59 Cd
2
0
d Molar, Corious
: 0.77c
1st Molar, Carlous
cc
r
C 0.69 Cd0
, 2
- - - - 7’
directly suitable for monitoring purposes.
Although large amounts of deciduous teeth
are readily obtainable with minimal effort, the tooth study records an historical event
Fic. 18. Strontium90 content of deciduous teeth as a function of the strontium90 content in milk. The lines were drawn for each type of tooth where
Gr and Cd represent pCi Sr90/gm calcium for tooth
which occurred some 5 to 8 years prior to
analysis of the tooth samples. The studies
with human bone depend on the haphazard
and unfortunate demise of human beings
by accident or from other causes which
(G) and commercial milk (C1) respectively. The 0 represents average values ± S:D. for 5 to 21 pooled samples obtained during periods of known milk values between 1954 and 1958. The plain circles (0) represent values obtained for estimated
milk values between 1950 and 1953.
0 I 2 3 4 5
206
nuclides, either by design or accident, war-rants the continuation of current studies. In
all probability, the continuous analysis of
milk and diets throughout the world
ap-pears to be the best system for obtaining immediate knowledge of Sr9#{176}fallout
direct-ly related to the accumulation of the
nu-clide in the human population. When the
correlation between dietary Sr9#{176}and the ac-cumulation of the nuclide in calcified
tis-sues is thoroughly documented and
under-stood, it will no longer be necessary to
measure the Sr#{176}#{176}content of the human
body. Until such a utopian time, studies of
teeth, bone, milk, and the environment
need to be continued and compared. For
the betterment of future human welfare,
the pros and cons of all scientific ideas and
disciplines must approach a common
ground for understanding this and other im-portant problems.
REFERENCES
1. Kalckar, H. M.: An international milk teeth
radiation census. Nature, 182:283, 1958.
2. Kulp, J. L., and Schulert, A. R.: Strontium90 in man and his environment. Report
NYO-9934. U. S. Atomic Energy Comm., 1:302, 1962.
3. Rosenthal, H. L., Custer, J. E., and Bird,
J. T.: Strontium90 content of deciduous hu-man incisors. Science, 140:176, 1963.
4. Rosenthal, H. L., Austin, S., O’Neill, S., Takeuchi, K., Bird, J. T., and Gilster, J. E.: Incorporation of fallout strontium90 in de-ciduous incisors and foetal bone. Nature,
203:615, 1964.
5. Rosenthal, H. L., Bird, J. T., Gilster, J. E., Pinto, P. V. C., and O’Neill, S.: Strontium90
content of deciduous teeth of children. J. Dental Res., 45:343, 1966.
6. Rosenthal, H. L., Cilster, J. E., Bird, J. T., and Pinto, P. V. C.: Regional variation of
strontium#{176} content in deciduous incisors. Arch. Oral Biol., 11:135, 1966.
7. Personal communications from C. M. Copley,
Deputy Health Commissioner, St. Louis De-partment of Health and Hospitals.
8. Reiss, L. Z.: Strontium90 absorption by decidu-ous teeth. Science, 134:1669, 1961.
9. KuIp, J. L., Schulert, A. R., and Hodges, E. j.: Strontium90 in Man. IV. Science, 132:
448, 1960.
10. Lough, S., Rivera, A. J., and Comar, C. L.: Retention of strontium, calcium and phos-phorus in human infants. Proc. Soc. Exp. Biol. Med., 112:631, 1963.
11. Bryant, F. J., and Loutit, J. F.: Atomic En-ergy Research Establishment (Great Brit.). Publication No. AERE R-3718, 1961.
12. Rivera, J.: Human bone metabolism inferred
