662
Sutow and Conard
1
\
these chromosomal aberrations has not been
established: in the absence oF sufacient information, the rel
5
:
logic changes to potentia
other abnonnaiities which wiht 6
occur iaier
o:
:
:
£ malformed intants or
deaths was round.”
Phe massive data trom tie ABCC survey
a
a
opuc lens occur after acute exposur
won exposure” anc reported: “No dermon-
stable, consistent eGect of parental exposure
ch
remains highly speculatixe.””
Other somatic evffccts, Opaciues
tne ABCC investigated 4,781 births to re-
sated arents with vaning feerees OF radia-
lens to doses greater than 2U0 rads of mixed
]
gamma and neutron radiation,?” I
the minimuin effective x-ray dose for the
production of clinically significant cataract
has been estimated to be 600 to0 et rads.
In chronic exposures, neutrons are consicered
to be more cuiaractogenic than N- OY gamunc
rays.” The semsluviiy of iemscs io radiation
setMis tO be yreaiust in infani uncer 1 year
oi age’ Prolonged temporary or permanent
sterility nas been reporicd folowing single
jocal yonacul doses or 500 rads or higher. lu
HEAROITARY ESPOCTS
5I1GH DOSE
In the stucics of atomic bomb survivors
at Hiroshima and Nagasaki by the ABCC,
CO
7s 1 Gp was concluded that the data could
demonsirate “no significant and conpsisient
effect of parental radiation exposure on th
ruumber of infants with major cerects, among
wie 76,026 children examined” anc failed
“LO reveal an Increase in stillbirtas or invant
deatus clearly atcvibutable to parental irra-
and, on the basis of this scparate analysis, a
nificant total genetic ¢ffect Nas been reported.**: °° However, the methodology and
interpretations of the reanalysis nave been
seriousiv Guesiicned by Neo! and Schull
Experimental siudies Ei organisms otner
than man have shown that the feccuency of
mutations was dose devsendent, even at the
lowest doses investigated. and ina: the wt
Jory oi: induced hereditar
changes lad
Gelraneniai Conmsequences. Aaourn direct
information is lacking. it an dears 2 easonably
certain inact simular eVecis occur
man being.?* Thus, known exposure to» his
doses of ionizing radiation requires the Cis-
quicting acceptance of genctic hazards, the
true magnitude of which may be assessed
only wita the perspective of ume strewching
over generauons.
so MATIC AND GSNETIC ZFFECTS
OF LOW-LEVEL RADIATION
The term
“low-leve.” raciauon, regarc-
The Japanese study, however, nus
less OF source, requires deAnition. The Unizec
would be consistent with the occurrence of
of Atomic Racaition (UNSCEARS has
avreed thar doses of Jess than 30 rad shorterm exposure and 100 to 1,000 mrac cumu-
a
sex-linked muitauons affecting prenaial survival¥ Schult y has examined the genet
interpretauon of theb cata, emphasizing the
reality of the effect but indicating that a
numouer of generic valternasives may account
for the change. A slight increase, however, in
ihe number of miscarriages, sullbirths, and
neonatal Geaths has been reported in the
Aiarshallese women exposed io fallout raciauion,”!
iSased on the assumption thar chilaren o:
consanguineous marriages, owing to their
increased homozygosity, are “a more sensitive
index of radiation induced genetic damage,”
vations Scientinec Commitee on the Effecis
lave weekly
coses should
be considered as
low." Ywo other frames of reference will
be userul in this discussion. one being the
amount of radiation from natura: sources 10
which man is constantly exposed and ihe
omer being the levels aces sted by severai
advisory and regulatory bodies as proiection
standards for the POT Yo 1 popwuiation.
According to UNSCEAK caleulauons of
fie
indicted a change
in sex ratio among offa
spring of irradiaied parents, Such a shiit
or
ciation.”
te
dose raics rom natural] raciution sources
da, oF
cosmic rays and terrestrial sources cu ch de-
liver about 30 mirem per year to ihe gonads,
bones, and blood-forming cells. The Inges-