The Human Plutonium Injection Experiments

bution of plutonium in the body.  Urine

assays of plutonium workers, again

coupled with occasional autopsy results,

increased that knowledge.

The usual problem, however, is the in-

verse: urine data are available but the

amount of intake, and perhaps the time

of intake, is not known.  In this case,

the current approach typically uses two

biokinetic components for plutonium

inhalation exposures: the first describes

how inhaled material enters the blood

system; the second relates the amount

in the blood to the amount excreted.

These two components translate urine

assays to a realistic estimate of the

amount of intake, and then the com-

plete biokinetic model is used to deter-

mine the distribution of that plutonium

throughout the body, which, in turn,

serves as the basis for calculation of ra-

diation dose to the individual.

The most uncertain step is this last

one—the calculation of a dose from a

known plutonium distribution.  For ex-

ample, although it is well established

that much of the plutonium in the bone

is concentrated on the endosteal sur-

faces, there is still a great deal of con-

troversy about how to calculate the ac-

tual dose from this deposition.  Pluto-

nium that is directly on top of the sur-

face will impart a much higher dose to

the osteocytes (bone cells) than plutoni-

um that is buried in the bone matrix,

even if only by a few hundred microm-

eters.  The only evidence that actual

doses may be less than was originally

assumed is the fact that none of the

human plutonium patients and none of

the plutonium workers (with one possi-

ble exception) who lived many years

with plutonium in their bodies have ex-

hibited any evidence of plutonium-in-

duced tumors.  This outcome is in high

contrast to radium, where many cases

of tumors were obviously present above

certain threshold levels.  

What about the one possible exception?

In 1975, George Voelz, a medical doc-

tor in the Los Alamos Health Division

published a study of the Los Alamos

plutonium workers, which discussed the

fact that one of the radiation effects of

radium poisoning was the development

of osteogenic sarcoma, a rare bone can-

cer.  He stated that “the age adjusted

death rate in the U.S. from all bone tu-

mors, including osteosarcoma, is only

about 1 per 100,000 persons per year.”

The appearance of 2 bone sarcomas in

15 cases of radium poisoning was evi-

dence that the sarcomas were, indeed, a

result of the radiation.  In 1989, one of

the 26 Los Alamos workers, exposed to

plutonium in 1945 and 1946, had an os-

teogenic sarcoma.  Bone sarcomas had

been observed in plutonium studies

with animals, including inhalation stud-

ies at plutonium levels comparable to

the maximum permissible lung dose for

workers.  In a 1991 paper by Voelz and

Lawrence, it was stated that the “dose

estimate for our case . . . is similar to

the lowest range of doses for dogs that

have developed bone tumors when ex-

posed to Pu . . . but is much below the

dose for the lowest Ra-exposed person

with a bone tumor.”  To insure a full

understanding of this one case, a new

dose calculation based on the two-term

power function is warranted.

However, this is the only possiblity to

date of a plutonium-induced cancer.

Most of the workers have lived longer

than average.  It would seem important

to continue studying the plutonium

workers.  Much could be learned for

little cost.  

It is also important to remember that

occupational health protection for pluto-

nium was approached with the radium

tragedy in mind, which resulted in prac-

tices and standards being adopted that

made it much more unlikely that the

threshold for tumors would be reached

with plutonium.  The almost total ab-

sence of such tumors indicates that the

practices established for plutonium

workers were, in the main, successful,

even though, from a statistical point of

view, the number of cases on which

conclusions can be based is too small to

be conclusive.  But that in itself speaks

to the fact that the radium industry was

a situation in which the workers, early

on, were in an unregulated and un-

knowingly hazardous environment,

whereas even though the plutonium

workers, early on, were working under

hazardous conditions, they were never-

theless kept apprised of the dangers and

given whatever safety equipment be-

came available.  As soon as it was fea-

sible, the work was moved into a high-

ly controlled environment in which the

safest procedures available were prac-

ticed and in which the equipment,

analysis techniques, and work proce-

dures were constantly upgraded as they

became available.

A great deal has been learned from the

human plutonium injection studies, but

much is left to be learned.  However,

the early studies were valuable enough

to enable our country to perform its

weapons research and production at the

end of World War II and into the cold

war with confidence that the workers

doing the work were being protected

and that the estimates of their plutoni-

um doses would be accurate.  The po-

tentially tragic consequences of work-

ing with a new and unknown substance

never came to be.  For this, we are

greatly indebted to the radiologists con-

cerned with insuring safety during the

Mahattan Project and are even more in-

debted to the patients who were inject-

ed with plutonium (see “‘Ethical Harm’

and the Plutonium Injection Experi-

ments” on page 280). 

s

Acknowledgements

Bill Moss would like to thank Darrell Fisher

for his encouragement and support, Gary Ti-

etjen for his work on the re-analysis of the

data as well as many helpful comments, and

George Voelz, Payne Harris, and especially

Julie Langham Grilley for their willing help

and valuable comments.

Further Reading

A collection of copies of the documents gathered

The Human Plutonium Injection Experiments

222

Los Alamos Science Number 23  1995

---