The Human Plutonium Injection Experiments

The Human Plutonium Injection Experiments

Number 23  1995  Los Alamos Science  

183

 

Stafford Warren was educated at

the University of California at

Berkeley from 1918 to 1922 and re-

ceived his M.D. from the University

of California Medical School at San

Francisco in 1922.  In 1925, he

was appointed as an assistant pro-

fessor of radiology at the University

of Rochester School of Medicine

and Dentistry, eventually serving

there as the Department of Radiol-

ogy Chairman.  In April 1943, War-

ren was appointed a consultant to

the Manhattan Project to establish

the Rochester site.  By November,

persuaded partly by management

at Eastman Kodak, who were run-

ning the uranium processing plant

at Oak Ridge, Warren was made

the medical director of the Manhat-

tan Project with headquarters at

Oak Ridge, Tennessee, and was

commissioned as a colonel in the

Army Medical Corps.

In the mid-thirties, Robert Stone, a

radiologist, and Joseph Hamilton,

an intern with a degree in chem-

istry, were recruited by Ernest

Lawrence from the University of

California Medical School in San

Francisco (at that time, part of the

UC, Berkeley system) to develop

biomedical applications for the

Berkeley cyclotron.  One applica-

tion was the direct treatment of

cancer, and Stone pioneered the

use of cyclotron radiation for exper-

imental treatment of human cancer

patients.  A second application was

to use the cyclotron to produce ra-

dionuclides for the internal ra-

diotreatment of disease.  By the

late thirties, Hamilton and Stone

were involved with human metabol-

ic and clinical studies using sodi-

um-24, a short-lived radioisotope.

They hoped sodium-24 could re-

place the long-lived radium iso-

topes for the internal radiotreatment

of certain illnesses.  Their studies

would involve using human volun-

teers—patients with leukemia, or

other illnesses, and normal healthy

subjects—to acquire comparative

data and to test for toxic responses

and evidence of cures.  The

amounts of the radioisotope admin-

istered to the patients were always

well below what were considered

toxic levels relative to the then rec-

ognized risks from external expo-

sures to x rays and internal expo-

sures to radium (from the use of

soluble radium salts to treat a wide

range of illnesses).

Louis Hempelmann’s medical train-

ing was at Washington University in

St. Louis, followed by a residency

in Boston at the Peter Bent

Brigham Hospital.  A fellowship

brought him to the Radiation Labo-

ratory at Berkeley in 1941, where

he studied radiobiology with Stone

and John Lawrence (Ernest

Lawrence’s brother) and worked on

the use of cyclotron-produced neu-

trons for therapeutic treatment of

cancer.  At that time, Hamilton was

doing other research with a variety

of radioisotopes, including the cy-

clotron-produced fission product io-

dine-131.  Many of those studies

used both normal human subjects

who had volunteered and patients

who were then tested for evidence

of responses that could lead to

medical treatments of illnesses, in-

cluding cures.  In a 1942 article,

Hempelmann said that “if the cy-

clotron finds no place in medicine

other than to provide ‘tagged

atoms’ for medical studies, the

medical profession will owe Ernest

Lawrence an everlasting debt.” 

 

s

 

A Radiotracer Experiment in the 1930s.

Joseph Hamilton (left) performs a tracer experiment in which the volunteer

drinks a solution containing radioactive sodium with his hand (out of sight)

inside a shielded counter that will detect the arrival of the radioisotope in

that part of his body.

The Medical Researchers

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generated in reactors at Argonne (twen-

ty miles southwest of Chicago) and

later at Clinton, Tennessee, and that

material would be processed into metal

at the Chicago Met Lab before being

sent to Los Alamos.  However, in May

1943, a committee appointed by Groves

reviewed the use of plutonium pro-

duced by cyclotrons and reactors and

decided it was necessary to locate the

final production steps for weapons ma-

terial at the same site that would assem-

ble the bombs.  Thus, Los Alamos was

assigned the responsibility of the final

purification and production of the pluto-

nium metal, starting with the Clinton

product in 1944 and, later, with large

quantities of the Hanford product

(which was sent to Los Alamos in the

form of a plutonium-nitrate slurry).

The Met Lab would also continue its

innovative research for Los Alamos on

the physical and chemical properties of

plutonium using, in 1944, milligram

quantities of the Clinton product.

The new assignment resulted in an in-

crease in personnel in the Chemistry

and Metallurgy Division at Los Alamos

from about twenty in June 1943 to

about four hundred by 1945.  It also

created an important difference in the

type of work at the two sites—the Met

Lab research was mainly “wet chem-

istry,” whereas the Los Alamos produc-

tion effort involved a considerable

amount of “dry chemistry,” resulting in

different types of health hazards, and in

particular, exposure to the airborne dust

of plutonium and its compounds.

In January 1944, at the same time the

first milligrams of reactor-produced

plutonium were being shipped from

Clinton, Seaborg and others at the Met

Lab began thinking seriously about the

fact that more and more people would

soon be working with gram quantities

of plutonium—perhaps thousands of

people at Hanford alone.  Hamilton had

probably informed Seaborg of a 1943

paper by Robley Evans about the dan-

gers of radium and the deaths of radi-

um-dial painters in the 1920s, in this

way alerting Seaborg to a potentially

similar situation with plutonium.  The

Evans paper estimated that as little as 1

or 2 micrograms of radium retained in

a person’s skeleton could cause cancer,

a latent radiation effect.  It also ex-

plained the reasoning behind the occu-

pational tolerance limit of 0.1 micro-

grams for radium retained in the body

(see “Radium—the Benchmark for In-

ternal Alpha Emitters” on page 224 for

a fuller discussion of the radium toler-

ance levels).  

Similarities with radium. That the

health risks for the intake and retention

of plutonium might be as dangerous as

those of radium was apparent from a

comparison of their chemical and nu-

clear properties.  Both elements were

heavy metals that were expected to de-

posit in bone.  Both had long half-

lives—1,600 years for radium-226 and

24,000 years for plutonium-239—and

both decayed by alpha emission.  A

comparison of their specific activities (1

microcurie per microgram for radium-

226 and 0.06 microcuries per micro-

gram for plutonium-239) and the ener-

gies of their alpha particles, including

those of the daughters of radium, im-

plied that plutonium might be a factor

of 50 times less effective than radium

at causing physiological damage.  But

because of the tragic deaths of the radi-

um-dial painters (dating from the use of

radium in 1917 to1918), it was impera-

tive to obtain metabolic data on pluto-

nium so that a safe tolerance limit

could be established for the Manhattan

Project workers.

On January 5, 1944, Seaborg sent a

memo to Stone, expressing his con-

cerns.  He offered to help set up safety

measures for handling plutonium and

suggested that “a program to trace the

course of plutonium in the body be ini-

tiated as soon as possible.”  Stone

replied by explaining Hamilton’s

planned tracer studies at Berkeley,

which would determine the metabolic

distribution of plutonium in animals,

and Hamilton’s need for milligram

amounts.  Hamilton had apparently

been offered microgram quantities of

plutonium-239 prior to 1944, but he

had informed Stone that “the studies

can be much more accurate and much

more quickly done” when milligram

quantities were available (see “Detec-

tion of Internal Plutonium”).  He pre-

ferred to wait until then to do the pluto-

nium metabolic studies, undoubtedly

fearing that experiments with smaller

amounts would lead to questionable re-

sults that would have to be repeated. 

On January 15, Seaborg sent a second

memo to Stone.

I am seriously worried about the

health of the people in my section,

for which I am responsible, since

they will soon handle such relatively

large amounts of plutonium.  I won-

der whether some plutonium should

be made available to Dr. Hamilton

for his distribution studies sooner

than the couple of months or more

indicated in your memorandum. . . .

The problem of health hazards as-

sumes even greater importance for

Site Y [Los Alamos] where so much

plutonium will be handled in so

large a variety of operations.  It is,

of course, also important in connec-

tion with the operations which will

go on at Site W [Hanford], particu-

larly those involved in its final 

isolation there.

In response to those concerns, manage-

ment at the Met Lab initiated discus-

sions about plutonium and its potential

for toxicity, beginning with a meeting

of the Project Council at the Clinton

Laboratory in Tennessee on January 19,

1944.  Compton summarized the deliv-

ery schedule for plutonium from the

Clinton reactor as 0.5 grams that

month, 3 grams in February, and 3 to 4

grams in March and indicated that the

Plutonium Project was “still in the

lead” in the race with the uranium iso-

tope separation effort.  

Tolerance limits. According to the

The Human Plutonium Injection Experiments

184

Los Alamos Science Number 23  1995

continued from page 182

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