The Human Plutonium Injection Experiments

injected ceased abruptly, and no

other human being has been delib-

erately injected with Pu since.

Gradually the classification was

downgraded, and the bulk of the

data now appear in the open litera-

ture.  Unfortunately, the material

from three of the four patients in-

jected by Dr. Hamilton [CAL-2,

CAL-3, and the patient injected

with americium] has never been

made available to anyone. . . .

Today, the production of Pu is

enormous, and all indications are

that it will increase.  More people

in the nuclear energy field are

being exposed to Pu and more are

expected to be world-wide.  Still—

all of our knowledge about Pu be-

havior in man rests on the sketchy

results [of] the patients injected in

the early days.  None of the

records are complete.

Durbin felt that, meager as they were,

the human plutonium data, gathered 25

years before, represented nearly all their

“human plutonium experience.”  Thus,

it was time to re-examine the data, es-

pecially in light of newer knowledge

(such as long-term animal data), and

bring together under one cover as much

as possible of the original detail.

Durbin visited many of the people asso-

ciated with the plutonium work, includ-

ing Langham and Christine Waterhouse

who, in 1971, still saw two of the sur-

viving Rochester plutonium patients.

She and Waterhouse discussed the pos-

sibility of obtaining further excretion

and blood samples and of performing

physical examinations and other tests.

The motivation behind the study of

long-term excretion was, of course, to

determine the radiation dose to a person

who had had an intake of plutonium.

The dose depended critically on the

amount of plutonium retained in the

body.  

In 1972, Durbin brought all the known

information about the patients together

and summarized the data in a review

article.  Because the excretion rate out

to several thousand days appeared to

have several regions with different

slopes, Durbin felt these regions might

be related to physiological changes, and

she fit both the urinary and fecal data to

equations that were a sum of exponen-

tials, one for each region.  The expo-

nential equations predicted total

amounts of plutonium excreted that

were somewhat larger than the amounts

predicted by Langham’s power function

(for example, 8.8 per cent versus 6.3

per cent after a year).  Durbin attributed

the increase mainly to the fact that she

had used data only from patients with

normally functioning excretory systems

(to better model healthy workers).  

Durbin summarized the dynamics of

plutonium in the body as follows:

Pu initially present in soft tissues

other than liver is cleared rapidly;

the major fraction is redistributed

to bone and liver, and a small frac-

tion is excreted.  Pu deposited in

the skeleton is mobilized in the nor-

mal course of bone remodeling;

some is redeposited in bone, some

is deposited in liver, and a small

fraction is excreted.  Pu deposited

in liver is eventually transformed

from relatively soluble forms in he-

patic cells into insoluble hemo-

siderin deposits and sequestered in

reticuloendothelial cells.  There-

fore, liver Pu is likely to be lost as

slowly as, or more slowly than,

bone Pu . . .  The loss rate from

the liver may eventually become the

rate-limiting process for Pu disap-

pearance from the whole body.

Thus, the picture of plutonium in the

body was much more dynamic than that

of simply “fixed” plutonium.  Although

plutonium appeared to be lost from the

bone faster than had originally been

thought, the consequence was an in-

crease in liver plutonium with time.

Durbin concluded that “liver is as criti-

cal an organ for Pu as is the skeleton.”

Twenty-seven-year excretion data. In

1973, John Rundo at the Argonne Na-

tional Laboratory in Chicago, working

with additional long-term urine and

fecal samples obtained by Durbin from

two of the Rochester subjects (HP-3

and HP-6), developed new equations

for the excretion data.  The new data,

taken about 10,000 days (27 years)

after the plutonium injections, did not

agree with predicted values—both the

urinary and fecal excretion rates were

more than a factor of ten higher than

those predicted by the models.  In fact,

when data on the plutonium workers at

Los Alamos were included, the values

not only appeared to be higher than

predicted but the curve turned upward

(the values at 10,000 days were higher

than at 1600 days), which raised ques-

tions about the validity of the models.

Deviations from the original equations

proposed by Langham were, in one

sense, not surprising.  The main aim of

the original human-injection studies

was to gather enough short-term data to

interpret urine assays a few weeks at

the most after an accident and decide if

plutonium workers had signficant inter-

nal doses of plutonium.  Trying to

apply equations describing short-term

data out to almost 30 years went well

beyond reasonable expectations.  Not

only were such data very meager, but

the techniques used to analyze urine

samples had changed several times over

the years, and so the data points were

not necessarily consistent.  The data

that were available—especially the

urine assay data of plutonium work-

ers—indicated that more plutonium was

being excreted than had been predicted

by Langham’s model, and thus the ex-

pected long-term dose would be lower

than previously thought.

Health effects. In 1976, R. E. Row-

land, from Argonne, and Durbin report-

ed what they had learned about health

effects on the various injectees, espe-

cially those who had survived for many

years and thus were more apt to show

the radiation effects of plutonium.

The Human Plutonium Injection Experiments

218

Los Alamos Science Number 23  1995

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