Evening star., 1948-10-27
Stars, Men and Atoms
Half Of Mans Body Seen
Changed Every z Months
Speed of Physiological Processes
Reported by Oak Ridge Scientist
By Thomas r. Henry


By Thomas r. Henry
man gets at least half new body every
two months.
This astounding conclusion has come from
study Of physiological processes, some Of which
take place with extreme rapidity, with radio.
active isotopes now being manufactured by the
Atomic Energy Commission, says DR.. Paul
Aebersold, chief Of the isotope division of the
commissions plant at Oak Ridge, Tenn.
These isotopes-particularly exploding So
dunn, phosphorus, iodine and carbon-now are
being furnished to medical laboratories all over
the world and the discovery of the astonish-
1ngly rapid rate Of cell renewal results from
large number of experiments designed for
other purposes.
Speed Unrealized Before.
1t long has been known that most body cells
are replaced many times during the average
lifetime. but Psychologists hitherto have not
realized the speed at which the rebuilding Of
human being takes place.
At least 75 per cent Of man Is water Work
with heavy water has shown, DR.. Aebersold
says, that one-half the water In the body is
turned over every two weeks. Only an infini-
tesimal amount Of water that composed the
great bulk OF the body of any man or woman
month ago is in the same individual today.
The 1sotope experiments have shown that
about half the atoms of sodium, potassium and
sulphur which constitute a considerable part
OF the nonwater part of the body are replaced
by new ones every month. 1t requires about
two months for half the carbon to disappear
and be replaced
Teeth and Bones Change
Some other atoms, like calcium in teeth and
bone, are exchanged very slowly, but still 1t
is unlikely that the average adult has much
Of the same teeth and bones present in child
hood.
The human body, DR.. Aebersold points out,
consists of about 10000 600 900 600 OO0, 900 OO0,-
000o coo atoms of all sorts While precise cali
culations are difficult because Of the extreme
complexity of physiological processes, 1t is al
most certain that more than half of these are
rejected and replaced by new ones each two
months. Whether any of them remain with
the individual from birth to death is quite
debatable.
Those rejected are released to the general
"atom bank" of the universe.
There hardly can be any question, Dr. Aeber-
sold says, that every person who reads this
has in his body a few millions of the atoms
that were once temporarily part of the body
Of Julius Caesar or the Queen of Sheba or
George Washington.
Shock to Aryans Seen.
Persons born pure -blooded Aryans, he points
out, may get shock to learn that their bodies
today are made up Of considerably more Negro
Chinese or Russian atoms than of pure Aryan
atoms.
The atoms are the building stones Of mole
cules which, in turn, are the constituents Of
cells, the microscopic, diversely shaped bricks"
which make up all living matter. Not all the
atoms In molecule or molecules in a cell
are replaced at the same time. The human
body is like a house which is not actually
rebuilt at any time but on which repairmen
are always at work. so that at the end of a
year or so there Is essentially nothing of the
original structure left.
The isotopes are revealing, DR.. Aebersold
said, that the physical process of living Is
dynamic far beyond any previous conception.
Experiments with radioactive sodium, for
example, have shown that at least so pounds
of this element, probably in units of single
atoms pass back and forth across the walls
OF the blood vessels every "A hours.
Rate Is Not Constant
The rebuilding. DR.. Aebersold points out does
not 60 on at constant rate all over the
body and for all types Of cells. This may be
one reason why the personality does not
change and why there is a continuity Of
memory. The rate of rebuilding can be fol-
lowed by Incorporating isotopes in cells, chiefly
through food, and finding the rate at which
new cells appear.
A precision has been attained by the use Of
the isotopes which hitherto would have been
incredible, he says 1t now is possible to detect.
for example, 100000 900 600, 900, ,0o0th %
billionth of billionthD of a milligram of radio
active iodine and millionths of bilionth of
mlligram of various other elements. This Is
at least thousandfold greater precision than
can be achieved by any other method Of chemi-
cal analysis.
The lower limit for detection, he says, seems
to be about 10000 atoms, which would consti-
tute grain of matter far below visibility with
the most powerful microscope.