fl)-yr i)oxe t.o) ,i!arrou’
0. r (milk-drinking
countries)
0,9 r (rice-eating
cotimi-tries)
PEDIATRICS, June 1960
929
fled iulrics
VOLUME 25 JUNE 1960 NutBEn 6
COMMENTARIES
THE RADIOACTIVE
“FALL-OUT”
PROBLEM
There
is no evil in the atom; only in iiiens souls.1T
lIE ADVENT of the atomic bomb as a military weapon has added a new group of constituents to the environment of man. These are the various radioactive fission products produced in the bombex-plosion. In addition, the released neutrons
serve to transmute a small quantity of at-mospheric nitrogen to radiocarbon. By “lo-cal” fall-out is meant the deposition of fis-son products in the area adjacent to the
site of bomb detonation. Large quantities
are also blown into the stratosphere, there
to circulate for variable periods of time
be-fore returning to the earth as “distant” fall-otit. Extensive studies by the Atomic En-ergy Commission2 and other governmental agencies (current expenditures for fall-out sampling exceed $12,000,000 yearly), as vell as by foreign governments, have al-ready provided a large body of observa-tional data on fall-out and radiocarbon ac-cumulation.
Fall-out products have been found in
many parts of the world-in the air, in vegetation, soil, water and food, and in hti-man tissues. Higher concentrations are found in the Northern Hemisphere. During the past few years the amounts have stead-ily increased. Since distribution is
world-wide, any particular sample chosen for
analysis contains extremely small amounts:
it follows that the anah’tic techniques are
difficult aIld subject to considerable error. It is customary, for example, to express the
observed quantities in terms of the
mi-cromicrocurie, which is 1012 curie, or 2.2
(lisintegrations per minute. Calculation of
the amount of radiation delivered to the
body involves a number of factors which
are difficult to measure accurately.
How much radiation does man now re-ceive? Table I is taken from a United Na-tions Report;3 the values are world-wide averages. Doses from natural sources, for
instance, are 14% greater at altitudes of 1,500 meters, doubled inside brick or stone
buildings, and some eight times greater in
Kerala, India, because of soil radioactivity. The importance of the average per capita
dose lies in the fact that it is the world
population which is at risk. It is evident that radiation from fall-out represents but a small fraction of the total received. In-terestinglv enough, the gonadal dosage
TABLE I
Es’ri MATEI) LD-WI in: I )ostu i’:s
iO-yr J)ose to (rmu,d,s’
Natural (rosillic rays, 3 r 7
1’)#{176},et(’,)
Man-made (diagnostic 0.5-5 r 7 + r x-ray, et(’,
AtOm 1)0011)5 (tests 0.01
TABLE II
Natural Occurrence
Te.?f. 5101) in 19.58
Leukemia 150 ,000/yr 0- ,000/yr 0-60 000/yr
Bone tumor ? 0- 900/yr 0-t5,000/yr
Major genetic defects 700,000-3,000,000/yr ,500-100,000 (total over many years) 300-40,000/yr
930 RADIOACTIVE “FALL-OUT”
from television viewing is of the same order
of magnitude as fall-out;4 the same is true, at least in the United States, from dental roentgenography.
The problem of vital concern today is
that of the potential biologic hazard from
distant fall-out (there is no question as to
the danger from local fall-out in the event of nuclear war). I use the word “potential”
advisedly because not only is there up to
now an absence of observable effects on
hu-man health as a consequence of radiation
from bomb tests, but no effects have been
detected in humans exposed to some 200
times as much radiation as has accrued to
date from fission products.
The information sought is the likelihood
of effects from low-level radiation
expos-ure. No laboratory experiments have ever
been conducted at radiation levels close to
natural background; although in a sense
this background is an experiment involving
large numbers of people over many
mu-lennia and yielding no definitive information
that man has suffered appreciable injury.
Thus only one avenue is open for
estima-tion of fall-out hazard-the extrapolation of
data collected on man and animals exposed to larger doses. The assumptions involved are difficult to test critically, and the
esti-mates derived are at present incapable of
verification by experiment.
It is in part a consequence of this
sci-entific impasse that we have heard such
diametrically opposite opinions as “. .
present contamination with strontium-90
fall-out is . . . extremely unlikely to induce
even one bone tumor or one case of
leu-kemia,”5
and,
“It is not unlikely that sometens of thousands of Americans will die of
bone cancer and leukemia caused by the
bomb
tests that have already been carriedout.”#{176}Confusion also arises because some
authors speak of cases or events per year
and others in terms of total effect which,
because of the recessive nature of much
genetic damage, covers many thousands of
years; some talk of average world-wide
dosages, while others emphasize areas of
highest concentration.
One estimate which has been made is set
forth in Table II, taken from a report of the
United Nations Scientific Committee;3 the
figures pertain to the world population.
A study made by Lewis7 indicates a
probability of only three new cases of
leu-kemia per year in the United States from
Sr#{176}#{176}produced thus far. Totter et al. and
Pauling#{176}predict 700,000 fetal and neonatal
deaths and 50,000 major defects during the
next 5000 years from C14 production.
Re-membering that the world population is
now some 3 billion, and that 70 million
births occur each year, the impossibility of
verifying these predictions is clear.
Every-one is agreed, however, that these two
isotopes, together with cesium-137, present
the greatest potential hazard: Sr9#{176}because
of localization in bone, and C’4 because of the fundamental role of carbon in
proto-plasmic structure. Pediatricians are under-standably concerned since Sr’#{176}uptake is
higher in infant bone.
Can anything he done to reduce the
in-take of Sr90? Reduction in milk
consump-tion is obviously not the answer (Table I),
ESTIMATES OF SOMATIC AND GF:NETIc DAMAGE
Fall-out
Te,ts (‘on/june
COMMENTARIES 931
though the pediatrician should be inter-ested to know that human milk contains
less Sr9#{176}than cow’s milk.’#{176} Resin-exchange
techniques for removal of Sr#{176}#{176}from milk would appear impractical on a large-scale basis. The possibility of increasing the
in-take of calcium (uncontaminated with Sr90)
in order to suppress uptake of Sr9#{176}by bone
has recently been suggested.6
In short-term experiments on rats, Sr#{176}#{176}
up-take was reduced by two-thirds when large
doses of calcium phosphate (equivalent to
1 gn Ca/kg) were given.” Long-term
stud-ies revealed that reducing calcium intake
to about one-tenth the usual level increased
strontium uptake by about fourfold, and
that quadrupling calcium intake reduced
strontium uptake by 50%.12, 13 High calcium
diets did not accelerate the loss of Sr#{176}#{176}
from bone. Recent experience with the
hypercalcemic syndrome of infancy would seem to render any large-scale use of high
calcium diets most unwise, particularly
since some commercial preparations of
cal-cium phosphate contain added vitamin D.
Everyone admits that more study of
human populations exposed to low-level
radiation is urgently needed,6 and many
have felt the need for more public
informa-tion. The St. Louis program,15 with its dual
purpose of collecting deciduous teeth for
Sr9#{176}analysis and of providing authoritative
information to the public, stands as an ex-ample of what can be done by an aroused citizenry. The American Academy of
Pedi-atrics has a standing Committee on
Radia-tion Hazards.
In the realization that forecasts of the
biologic hazard from fall-out represent merely estimates-which are at present im-possible to verify-many have sought refuge
in the ethical and political issues inherent
in the bomb-testing program. For some, the
question is that of balancing a long-term
biologic risk against a short-term one,
namely nuclear war, with the latter consti-tuting by far the greater hazard to civilized
* Recent data,’4 for example, indicates that
muta-tion frequency of genes is a function of dose rate.
man. Others reply that fall-out products
reach everyone on earth, and that the
ad-vanced technology of the two great powers
cannot justify world-wide pollution, nor can
the specter of military unpreparedness
countenance the harming of even one
hu-man being by fall-out. The scientists who
have taken sides in this controversy should
pause to consider that even in this modern age the decision as to war or peace is a political, not a scientific one. They may be
called upon to forge the weapons of var,
and to advise as to the hazards involved in
their use, but the ultimate decision rests
with the body politic. “Once the real prob-lems are clearly identified, then the
govern-ment will be in a position to determine what
specific action needs to be taken and where
to fix responsibilities for such action.”16
Perusal of the voluminous hearings held by
the Congressional Joint Committee should
quickly dispel any notion that our
govern-ment is unaware of the biologic
implica-tions of the nuclear age.
Each major advance in technology has
resulted in some human misery: the
indus-trial revolution brought with it an increase
in the infant mortality rate, the
pasteuriza-lion of milk an increase in scurvy, better sanitation an increase in poliomyelitis. The modernist, however, should be far better prepared to appreciate the undesirable by-products of his actions. The peaceful use of atomic energy will in time provide fully as great a potential hazard as the bomb-testing
program. We must learn to live with this
new technology in the years to come.
GILBERT B. FORBES, M.D.
Department of Pediatrics
University of Rochester
Rochester, N.Y.
REFERENCES
1. Stevenson, Adlai: Speech, Hartford, Conn.,
Sept. 18, 1952.
2. Hearings before the Special Subcommittee
on Radiation of the Joint Committee on
Atomic Energy. Congress of the United
States: May, 1957; ibid., May, 1959.
3. Report of the United Nations Scientific
Ra-932 RESISTANT RICKETS
diation. Official Records: 13th Session,
Suppl. No. 17, New York, 1958.
4. Braestrup, C. B., and Mooney, R. T.: X-ray
emission front television sets. Science,
130:1071, 1959.
5. Finkel, Ni. P.: Mice, men and fallout.
Sci-ence, 128:637, 1958.
6. Pauling, L.: Letter to New York Times,
September 13, 1959.
7. Lewis, E. B.: Leukemia and ionizing
radia-tion. Science, 125:965, 1957.
8. Totter,
J.
R., Zelle, M. R., and Hollister,H.: Hazard to man of carbon-14.
Sci-ence, 128:1490, 1958.
9. Paulmg, L.: Genetic and somatic effects of
carbon-14. Science, 128:1183, 1958.
10. Environmental contamination from weapon
tests. U. S. Atomic Energy Commission,
Office of Technical Services, Dept.
Corn-merce, Washington 25, D.C., 1958. 11. MacDonald, N. S., Spain, P. C., Ezmirlian,
F., and Rounds, D. E.: Effects of
cal-cium and phosphate in foods on
radio-strontium accumulation.
J.
Nutrition,57:555, 1955.
12. Palmer, R. F., Thompson, R. C., and
Kom-berg, H. A.: Factors affecting the rela-tive deposition of strontiulll and
calci-um in the rat. Science, 128:1505, 1958.
13. Thompson, R. C.: Personal communication.
14. Russell, W. L., Russell, L. B., and Kelly,
E. M.: Radiation dose rate and mutation
frequency. Science, 128:1546, 1958.
15. Greater Saint Louis Citizens’ Committee
for Nuclear Information, 2 Oak Knoll
Park, St. Louis, Missouri.
16. Summary-analysis of 1959 Hearings, p. 35
(italics mine).
MULTIPLE
GENETIC
MECHANISMS
IN
VITAMIN
D-RESISTANT
RICKETS
V
ITAMIN D-resistant rickets of the “sim-pie” type is one of the most commonlyencountered forms of metabolic bone
dis-ease in modern pediatric practice. In this
disorder, rickets similar to that due to
vita-mm D deficiency develops in the face of
usually adequate amounts of vitamin D and heals only with massive and sustained doses
of the vitamin. Biochemically, the cardinal
abnormality is hypophosphatemia, appar-ently the result of diminished tubular
re-absorption of phosphate from the
glomeru-lar filtrate. \Vhether the renal abnormality
is based upon a primary defect within the
tubule cell or is a secondary effect, as for
example from secondary
hyperparathyroid-ism, is not yet known. Other obvious
bio-chemical abnormalities such as
aminoacid-uria, glycosuria, acidosis, potassium deple-tion or water-losing are absent.
It is widely recognized that vitamin
D-resistant rickets occurs in families. Several
investigators have suggested that the dis-ease is usually transmitted as an autosomal
dominant trait, a conclusion drawn from
studying small kindreds using exclusively
clinical methods for diagnosis.
During the past 5 years, five apparently
unrelated families with vitamin D-resistant
rickets of the “simple” type have been
studied at the University of North
Caro-2 Altogether these families have
con-tamed 720 persons, including 91 who have either had unequivocal hypophosphatemia
or (if dead) a clear history of bone lesions.
These studies have greatly clarified the
in-heritance and, to a lesser extent, the mecha-nism of the hypophosphatemia.
It was discovered early that some persons
(
usually female) without clear-cut clinicalor radiographic bone lesions had
unequivo-cally low levels of inorganic phosphorus in the serum compared to normal persons. This
discovery was not possible prior to the
de-velopment of “normal” ranges for serum
in-organic phosphorus, ranges which are
spe-cific for both sexes and all ages.’ In every
instance, the “asymptomatic” but
hypophos-phatemic persons proved to be related as children, parents or siblings to persons who
had the overt clinical, radiographic and
biochemical signs of the disease. The
pres-ence of hypophosphatemia was thus shown
to be a much more sensitive index of the
trait than bone lesions. For example, when
only clinical and radiographic criteria were
used, “skipping” of the trait appeared to
have occurred almost half the time. When
the gene was traced on the basis of
