Evening star., 1952-03-17
Second Of o Series


hundreds of chemicals. by a va
riety Of rays, by certain viruses,
by breeding cancer" into spe-
cies, by physical irritations, by
changing the hormonal secretions
OF the body.
Because humans cannot be used
experimentally as are laboratory
animals, less is known about
human cancer.
But, thanks to extensive sta
tistical studies and the careful
tracing Of histories of some cancer
patients, many Of the causes Of
mans cruelest and second most
prolific killer are coming to light.
Many Factors Involved.
At this point. it looks as though
human cancer is the product Of
the imperfect hormonal and other
systems we were born with. of the
chemicals we contact in our work,
of our daily habits and practices.
of certain rays and physical ir-
ritations, even of factors accom-
panying ageing.
1. We cannot be sure of the source
Of most cancers.
It takes 20, or 80 or even so
years for some of them to develop
from tiny cells to tremendous,
deadly tumors.
S In laboratories throughout the
United States, many scientists
are working overtime to find out
what causes cancers. They are
inquiring into plant, animal and
human inheritance Of cancer.
They have found by inbreeding
experiments that cancer can be
inherited by 90-odd per cent of
the offspring of mice. rats, fruit
flies and other animals. But the
caNcerous strains are developed
only after many generations OF
careful brother to sister mating OF
the most-susceptible animals.
Even then, some highly suscep-
tible animals must have a virus
and an inherited hormonal i'm
balance as well as certain genes
to develop cancer.
Cancer Not Inherited.
The animal experiments and
statistical studies are showing that
humans do not inherit cancer as
such. Human fears Of Inherit
ing cancer" are baselesS. Too
much or too little production OF
certain hormones may be In
herited; and this may give q
tendency to cancer.
! Science so far has found about
eight classes of chemicals which
cause cancer in experimental
animals.
: some Of these compoundS-
hundreds in all-are contacted
hy humans. They are breathed IN
as fumes; or they are handled at
work: or they may even be eaten
IN certain foods. The case against
them, as causes Of human cancer.
ftill is for the most part highly
eircumstantial.
The kind of hydrocarbon mole
cules which make up SCOT and
tars cause cancer. So do oils OF
the type which boil at very high
temperatures.
A Chicago scientist has found
that hydrocarbon used to proc
ess rubber-the kind used IN tires
and bottle stoppers-will cause
cancer in animals.
Dyes, Arsenicals Blamed.
It has long been known that
analine dye workers develop
bladder cancer, and uranium
miners frequently get lung cancer.
Arsenicals also cause cancer.
Some doctors and others who
are exposed a great deal to radia-
ton from x-ray and Horoscope
equipment have a much higher
incidence Of leukemia and other
forms Of cancer than exists among
the general public.
Farmers and sailors, whose
eallings entail long hours Of ex-
posure to the suns rays, have a
high rate Of skin cancer. The
lighter the skin, the greater the
cancer risk.
The American Cancer Society
now is conducting a 10-year study
iof smokers and non-smokers
throughout the United States to
determine whether use Of tobacco
has any connection with lung
cancer, whose occurrence has
.tripled In 81 years. Previously
several short-term surveys, by
individuals, indicated relation