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Cancer
The present inoldence of bone sarcoma in this country is about
2000 cases annually. What, if any, part of this is the result of na~
tural radioactivity is not knowm.
It is quite apparent from the observatias
of radiotherapists that a dose of external radiation of something more
than 1000 r given locally to the bone is required to induce cancer, and
cancer induction by doses of less than 2000 r is a very rare occurrence.
As to the induction of cancer by chronic irradiation from bone~seeking
radionuoleids we have a considerable body of data in humana (3, 24).
Practically all of this information deala with exposure incurred during
adult life,
In the recent studies ten of the fifty persons who received
radium therapeutically were discovered because of symptoms attributable to
the radiua such as bone marrow, while of the twenty-eight luminous dial
workers studied sixteen came under observation because of symptoms.
they represent a heavily biased sample.
Thus,
In order to achieve a more complete
picture of radium and mesothorium toxicity in humjns studies have begun on
several hundred additional exposed sergons not known to have symptoms at
the present time.
Briefly it can be stated that no case has come to our
attention of bone cancer in an individual exposed to sure redium salt in
adult life who had left in him at the time of observation (usually 20-30
years after the material was ingested) less than 1.3 microcuries of radium.
The National Committee on Radiation Protection and the Internations]
Commission on Radiological Protection have taken a little loss tian
1/l10th of this figure, 0.1 microcurie, as the permissible radium burden
for adult workers an‘ 1/10th of that or 0,01 pe for the population as
a whole.
“ith radium the exposure to the bone is not uniform.
If it