The Human Plutonium Injection Experiments

The Human Plutonium Injection Experiments

Number 23  1995  Los Alamos Science  

195

Other human experiments involved var-

ious toxic heavy-metal radioisotopes

that were either materials important for

the development of the atomic weapons

(polonium and uranium) or were part of

a comparative evaluation of health haz-

ards (radium).  The polonium studies

helped to develop techniques for the

similar but later studies with plutonium

(see “Polonium Human-Injection 

Experiments”).

One of the main problems in the polo-

nium studies was contamination.

Working with the material could easily

contaminate laboratory equipment used

in the analysis, which, in turn, could

bias results or even contaminate sam-

ples related to other studies.  It was

thus anticipated that analysis procedures

for plutonium would require laborato-

ries that were absolutely free of alpha

contamination.  A “clean laboratory”

was established at Los Alamos in Feb-

ruary 1945 in the Medical Labs Build-

ing, and the responsibilities in the plu-

tonium study were split.  The Medical

Corps or the Rochester Project would

handle the clinical work, and Los

Alamos would analyze the resulting 

biological samples. 

The First Human Experiments

with Plutonium

Reports issued in 1945 show that three

human plutonium-injection studies were

authorized in April 1945—a study by

the Chicago Met Lab Health Group, an-

other by Hamilton’s group in Berkeley

and San Francisco, and a third study to

be done jointly by Warren at the Army

Medical Corp Hospital in Oak Ridge

(clinical) and the Los Alamos Health

Group (analytical).  The three ap-

proaches would allow using plutonium

in two different valence states (+4 and

+6), two different chemical forms (cit-

rate and nitrate), and two different iso-

topes (plutonium-239 and plutonium-

238).  Each group would be responsible

for analysis of excreta samples using

their own plutonium analysis technique

developed for that purpose (the cupfer-

ron-extraction method at Los Alamos,

the cation-exchange method at Chicago,

and the thiophenyltrifluoroacetone ex-

traction method at Berkeley).

The plutonium-239 dose decided on for

the Oak Ridge-Los Alamos and the

Chicago studies was 5 micrograms.

That quantity would enable the Chicago

group to detect plutonium accurately

using 100-milliliter urine-sample

aliquots of 24-hour collections and

would provide appropriate activity lev-

els for the Los Alamos method, which

used full 24-hour urine samples.  The

Berkeley site, however, would use a

different isotope, plutonium-238, at a

different dose level; the injected mass

would only be 0.2 microgram, but be-

cause of a much higher specific acti-

tivy, it would have 10 times the ra-

dioactivity.  As a result, the excreta

samples at Berkeley would also be ex-

pected to have more than ten times the

activity of corresponding samples from

the other two studies, increasing the 

accuracy and precision of the alpha

measurements on the excreta samples.

Oak Ridge. The first human plutonium

injection occurred on April 10, 1945,

barely two weeks after the meeting in

Los Alamos between Friedell, Hempel-

mann, and others.  The person chosen

for the experiment was a 55-year old

man and a patient at the Manhattan

Project Army Hospital in Oak Ridge.

(Although the man was the first patient

injected with plutonium, he was later

grouped in reports with other patients

injected at the Rochester site and was

identified as HP-12.)*  He had been

hospitalized because of injuries in an

automobile accident, and bones in his

right forearm, left thigh, and right knee

were broken.  Some of the fractures

were “in poor position,” which meant

an operation to properly set the bones

would be necessary.  Except for those

injuries and “a chronic urethral dis-

charge which he has had for 10-15

years [his clinical record states this may

have been due to chronic gonorrhea],”

HP-12 had always been employed as a

cement mixer and was generally in

good health (“well developed, well

nourished”).

In a report for a conference on plutoni-

um, held May 14 and 15, 1945, Wright

Langham stated that “the person was an

elderly male whose age and general

health was such that there is little or no

possibility that the injection can have

At the present time the

hazards of workers at Site

Y are probably very much

more serious than those at

any other branch of the

Project. . . . it would be

appropriate that the med-

ical program of the Man-

hattan District consider

some of our problems

rather more intensely than

they have in the past.

*Many of the names of the people who were in-

jected with plutonium have been published else-

where.  However, we did not want to intrude fur-

ther on the families of those people and so will

only identify the patients by case number.

---

any effect on the normal course of his

life.”  HP-12 was 53 at the time of the

injection and lived another 8 years be-

fore dying, in 1953, of heart failure.

Late radiation effects, such as cancer,

were not expected to develop for ten to

fifteen years, if at all.  For example, the

induction period in humans for radium-

induced cancer, especially malignancy

of the bones, was about 10 to 30 years

after exposure.  Despite Langham’s

statement, we cannot, of course, dis-

count the fact that HP-12 might have

lived 20 or more years; although in

1945, fifty years of age was considered

to be fairly advanced.  On the other

hand, the GIs at Los Alamos who were

heavily exposed to plutonium in 1945

while working in D Building under

poor industrial hygiene conditions (see

“On the Front Lines” on page 124)

were in their early twenties and were at

greater risk of developing late radiation

effects than was HP-12.

HP-12 was injected with 4.7 micro-

grams of plutonium (0.29 microcuries)

in the chemical form of the +4 citrate

salt.  The material had been sent to Dr.

Friedell at Oak Ridge by Wright Lang-

ham, along with directions for its use

on a human subject.  Langham stated

that citrate was chosen “to produce the

maximum deposition in the bone . . .

[so as to] produce an excretion rate

comparable to that of a worker having

absorbed the material at a slow rate.”

Urine samples were collected almost

continuously for the first 42 days, and

then intermittently until the 89th day

after injection.  Regular stool samples

were collected as well over a 46-day

period.  In accordance with the plan,

the Manhattan District Medical Office

conducted the clinical part of the exper-

iment, and the urine and fecal samples

were sent to Los Alamos for analysis.

Langham also reported at the May con-

ference that “the excretion during the

first day was surprisingly low [0.1 per

cent in the urine] and . . . the leveling

off of the excretion rate was much

slower than with rats.”  Langham sug-

The Human Plutonium Injection Experiments

196

Los Alamos Science Number 23  1995

Polonium Human-Injection Experiments

In 1944, in response to concerns for the risk associated with occupational

exposures to polonium, the Army Medical Corps authorized Rochester to un-

dertake a study of the biological behavior of that element.  The program was

started in August 1944 with animals, and by November, studies with humans

had begun.  Eventually, tracer amounts of radioactive polonium-210 were in-

jected into four hospitalized humans and ingested by a fifth.  

Polonium, the first element isolated by Marie and Pierre Curie from pitch-

blende in 1898, is an alpha emitter.  When alpha particles from polonium-

210 collide with beryllium atoms, neutrons are ejected, and polonium-berylli-

um combinations had already served physicists as a convenient source of

neutrons.  During the Manhattan Project, it was decided to use that neutron

source as an initiator of the chain reaction in the atomic bombs, thus making

polonium (and beryllium) an occupational health hazard for the people who

needed to develop and build the initiators.  

In the Rochester work, the subjects of the excretion studies were volunteers.

The problem had been outlined to patients at the Rochester Hospital, who

were told that it would involve the intake of tracer amounts of a radioactive

substance followed by analysis of their excreta.  Because polonium was not

classified at that time,* the doctors may have even told the patients what

substance they would be injected with.  From the group of volunteers, four

men and one woman were selected for the studies.  They ranged in age

from the early thirties to the early forties and were being treated for a variety

of cancers (lymphosarcoma and various leukemias).  One patient died from

his cancer six days after the injection.  

Four of the volunteers were injected with doses of polonium in a soluble

form that ranged from 0.17 to 0.3 microcurie per kilogram of body weight.

The fifth patient drank water containing 18.5 microcuries of polonium chlo-

ride, equivalent to 0.19 microcuries per kilogram of body weight.  The

amount of polonium excreted in urine and feces were analyzed, and blood

samples were taken to determine the amount freely circulating in the blood.

Autopsy tissue samples were taken from the patient who died to determine

the distribution of polonium throughout the body.

Polonium-210 has a short half-life (138 days) and very high activity (4,490

microcuries per microgram).  The high activity meant very small quantities

(of the order of nanograms, a factor of 1000 less than for plutonium) could

be administered and detected, so concerns of chemical toxicity were mini-

mal.  The short half-life meant the substance would not remain in the body

so that concerns about long-term radiation effects were also minimized.  In

1945, urine assays corresponding to the tolerance limits were 7 counts per

minute for plutonium-239 but 1500 counts per minute for polonium-210.

Such metabolic studies were possible at Rochester University in 1944 be-

cause polonium was available at that time.  The research yielded important

information for the Manhattan Project on the hazards of polonium and

helped develop techniques for the similar but later studies of plutonium.

*Polonium was classified in July 1945 and given the code name “postum.”

---