supphes varies greatly, but some has been found im
ewentially all sources. Rain will be radioactive,
owing to the natural radioactive materials in the
air. Not only is radioactivity found in air and water,
but the amounts vary widely from place to place
and time to time.
ited quantity of fich containing above-maximum
permissible concentrations might be eaten safely,
but their continual consumption would be undesirable.
The presence of such radicactivity in tuna fish
was reported by the Japanese following the Pacific
test in the spring of 1954. The highest activity reported by the Japanese was found on the skin of
the fish aboard the vessel Fukuryu Meru (Fortu-
nate Dragon). This was the ship that received the
direct fallout on the day of detonation, ! March
1954, and the source of the radioactivity measured
on the fish was principally the direct surface con-
tamination as the fish lay shoard the veel. The
quantitative levels of activity found on these fish
of the fish. This later activity is considered safe for
standards. .
Geactics. There are five relevant pemmts concernimg radiation and genetics thet may be enumerased.
1) Radkation cam cause itveversible mberiable
changes (called gene mutations) im the gern colle.
Mos of these mutations ase considered harasful.
2) The aumber of mutativasproduced is inde-
Hiyf
tiI
Ai
| |i
Lith |
pendent of the rate of radingien expanere; that is,
a ss che total exposere we a gives kind of sadision:
that « the swportanc factor.
¥
‘
Radicons have ast produced sev kinds of
wally. Thus. the pomuhie effects of radiation fram
d
4
the “recemve™ repe thar mev be cared genere-
the mmaxumeess permambic ansownt—e quasun con-
sdered sabe—even if the waser had been mared ond
used as the sale source of mapply for 3 kirume { {2}.
Radwaczne matrrals hove bern foued m planseon and alger m bagher comrentrauces thas mn the
eurroundmag weerr, When fish ent these marine
|
organeus, a small fraction of thes radmacmay 8
ten afr generation withowt expremion wal & is
wae->l lh . seleg mutant gene m the oppomer
sex- 22. xcurrence of very low probabii m a
geacral popuianon such 2s ours that & out-breeding
ewne to ubou scams marriage of close relatives) .
Thum. the presence of a mutant gewe ver: carey
means a “defective” mmdrvidual m the sense of de
eectable defects.
5\ It bas been estemaeed that aatural causes ‘ef
which radiation from sormal sources accounts for
eal: 10 w 20 percent) (20° mav produce on mm
average two additional mutations arsong every five
parents, we mav have op an average four “new”
| @uracens in every five individuals. rn addin t
THE SCIENTIFIC MONTHLY
ro oe
with thoer produced . sarural causes.
4. Lf che sueemen thet occuss is of the “domimame” rvpe. them the effert appears mm the.fru
gemereuce. It is belteved. however. that bx far the
‘wryest munsber ef mutetons thet do orcur are of
PO er ae
metieas dewnatiens cebefullt may be compared
i
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f
t
meutatees eet alread. knows and eccurneg ast
i
e
3
PoNe we
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Oebii
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Bet
a + peryf
are unknown, but thereafter the highest activity
was 1300 counts per musute measured by a Geiger
counter, with shield open, held close to the surface