United States
Environmental Protection
Agency
Environmental Monitoring Systems
Laboratory
Las Vegas NV89114
 Research and Development
EPA-600/S4-82-069  Mar. 1983
Project Summary
Plutonium  Burdens  in  People
Living  Around  the  Rocky  Flats
Plant
John C. Cobb, B. Charles Eversole, Philip G. Archer, Roxanna Taggart, and
Deward W. Efurd*
  A study was conducted to find out
whether the tissue of people who had
lived near to or downwind from Rocky
Flats Nuclear Weapons Facility in Colo-
rado contained more  plutonium (Pu)
than the tissue of people living farther
away.  In addition to tissue analyses,
investigators obtained information on
age; sex; smoking, occupational, and
residence history, and causes of death.
The tissue samples were collected from
autopsy cases  during the period 1976-
1979.  The purpose of the study was to
measure levels of Pu-236, Pu-238, Pu-
239 and Pu-240, and the Pu-240/239
ratio in the tissue of people who had not
been occupationally exposed and who
died in Colorado over that three-year
period.
  Samples were collected from human
autopsies in each of three collection
areas: Area A -- up to 25 km from Rocky
Flats; Area B ~ between 25 and 50 km
from Rocky Flats; and Area C - all of
Colorado outside  a 50 km  radius of
Rocky Flats and east of the Continental
Divide.
  With plutonium concentrations in lung
and liver tissue as the dependent vari-
able, a stepwise,  multiple regression
analysis was used to test the data with
independent variables of age, packyears
of cigarette  smoking,  and distance of
residence from Rocky Flats, analyzed
separately by sex and for selected areas.
  The Pu-240/239 ratios in the liver
were significantly higher than in the
lung, and the total amount of plutonium
burden in the liver was about 10 times
'McClellan Central  Laboratory, currently at Los
 Alamos National Laboratory.
greater than in the lung. These observa-
tions reflect the longer retention time of
plutonium in the liver.
  Results indicated that sex, age, and
smoking history were all more strongly
related to plutonium burden in the liver
than distance from Rocky Flats.  Addi-
tionally, results show that a male at the
average  age of 65.4 years, as in this
study, would have 1.5 times more pluto-
nium in his liver if he had been an 80-
packyear smoker than if he had been a
nonsmoker.  For a 50-packyear smoker
at the average age. the ratio would have
been 1.3 times more plutonium.
  The data on concentration and total
lung burden  and on  the Pu-240/239
ratio in  lung  and liver suggest that
releases of plutonium from Rocky Flats
contributed  only a small amount to
plutonium burdens in humans east and
southeast of the site, as the total amount
of plutonium in human tissues was small
and not very different from that ob-
served by other researchers who have
studied people from other  locations in
the nation.

  This Project Summary  was devel-
oped  by EPA's Environmental  Moni-
toring Systems Laboratory, Las Vegas,
NV, to announce key findings of the
research project that is fully document-
ed in a separate report of the same title
(see Project Report ordering informa-
tion at back).

Background
  At the request of Senator Haskell of
Colorado, a study was conducted to find
out whether the tissue of people who had
lived near to or downwind  from Rocky

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Flats contained more plutonium than the
tissue of people living farther away. For
those deceased who were autopsied and
who had lived in eastern Colorado at least
five years, information was collected on
age; sex; smoking, residential, and occu-
pational history;  cause  of  death;  and
presence of pulmonary or liver disease.
Samples of lung, liver, gonads,  adrenals
and  rib were  collected  for plutonium
analysis.  The isotopes for which the
samples were analyzed were Pu-236, Pu-
238, Pu-239, Pu-240 and the ratio of Pu-
240 to Pu-239. Plutonium in tissue from
Colorado residents can arise from both
worldwide fallout and from local sources
such  as the Rocky Flats  plant  near
Boulder, Colorado.
  The  amount  of  global atmospheric
plutonium  varies  from  year  to  year,
depending on the types of atomic bombs
being tested; however, the bulk of pluto-
nium from American and Russian nuclear
test programs fell from the atmosphere by
1968.  Subsequent measurements  show
that the amount of plutonium has been
declining ever since.
  A possible  source  of plutonium in
Colorado was a September  1957 fire at
the Rocky  Flats  plant, which  released
plutonium-seeded smoke that was swept
southward by a prevailing wind (Hammond,
1971).  Another release occurred be-
tween  January and June of 1968 and
during  1969, when drums containing oil
contaminated with plutonium were being
moved. Several were damaged, releasing
into the soil plutonium particles that were
then resuspended in the air during high
winds  (Seed,  1971).   These  are two
known acute releases from  Rocky  Flats;
others  could have occurred, and a con-
tinual,  very  low level  was probably re-
leased from normal operations.
  Several other possible sources of pluto-
nium exist in Colorado. Until September
1980,  there had  been 565  tests at the
nuclear test site in Nevada, of which 140
tests produced measurable  amounts of
radiation outside site boundaries (Hicks,
1981).  Also, since 1968, the Peoples'
Republic of  China has conducted about
20  nuclear weapons tests that  added to
the global plutonium inventory. Since the
Chinese tests were relatively recent and
the retention half-time of plutonium in
lung tissue is 500 days, a related contri-
bution of plutonium to the lungs of people
recently living  in Colorado could exist.
  Atmospheric transport and  diffusion
processes  would  have  dispersed the
nuclear test site  and Chinese debris
clouds before they  reached Colorado, so
that  plutonium  loads would have been
randomly distributed in  the soil  of the
state. By contrast, weapons-grade pluto-
nium released by the Rocky Flats plant
would be concentrated near the facility.
In addition. Rocky Flats plutonium has an
isotope  ratio (240/239) of 0.06 com-
pared to a worldwide fallout isotope ratio
of 0.18, so that measurement of the Pu-
240/239 ratio in a sample permits an
estimate of the  Rocky Flats contribution
to the sample.
  The highest known concentration  of
plutonium in the air in Colorado occurred
during the 1957 fire. The relatively high
level at  that time was probably of short
duration as compared to the lower, more
sustained  levels associated with  the oil
drum spills during 1968  and 1969.
  Many measurements of soil plutonium
concentration  levels have  been  made
around the perimeter of Rocky Flats. They
show a much higher concentration  of
plutonium east and southeast of the site
than at distant locations.  This is probably
due to prevailing winds  that blow from
west to east Relatively little soil contam-
ination was found  south,  west  north-
west, or northeast of the site.
  If  the fire  and spills  at  Rocky Flats
between 1957  and 1968-1969 caused
plutonium  exposure to  local residents
that  was  excessive in  comparison  to
plutonium exposure from worldwide fall-
out,  then an increased concentration  of
plutonium in tissue could  be expected
now among those who lived downwind
from Rocky Flats during that period. This
could be detected by a low ratio of Pu-
240  to Pu-239 in lung tissue, where the
retention half-time of plutonium is rela-
tively short.
  The usefulness of the study was not
limited  to  the  questions  about  Rocky
Flats but included inquiry into the rela-
tionship between smoking  history, age,
sex,  cause of death, and plutonium con-
centrations in liver and lung.

Methods and Procedures
  The study was coordinated by the U.S.
Environmental Protection Agency (EPA),
Environmental Monitoring Systems Lab-
oratory,  Las Vegas, Nevada, and con-
ducted  by the University  of Colorado
Medical Center and the  Colorado State
Health Department Fifteen hospitals in
Denver,  Pueblo, and Colorado Springs
collected tissue samples for the study.
  Samples were  collected  from  human
autopsies  in each  of three collection
areas: Area A -- up to 25 km from Rocky
Flats; Area B ~ between 25 and  50 km
from Rocky Flats; and Area  C  —all  of
Colorado outside a 50 km radius of Rocky
Flats and east of the Continental Divide. A
total of 519 samples were coJIected, 147
from Area  A, 182 from Area B, and 190
from Area C.  (See Figure 1.)   Samples
came mostly from heavily populated
areas around Denver, Colorado Springs,
and Pueblo, with  scattered cases from all
of eastern  Colorado. Only three samples
came from places within 10 km of Rocky
Flats, because the area was very sparsely
settled.
  Each set of samples generally included
one whole lung, 750 grams of liver, both
gonads, if available,  both  adrenals, if
available, and a sample of rib. Interviews
with next  of kin  yielded places of resi-
dence of  the deceased, any possible
occupational plutonium exposure, smok-
ing history in packyears, age, sex, and
cause of death.
  In  lung  tissue, the  plutonium is less
evenly distributed than in the liver, and
much of  it is deposited in the lymph
nodes. Hence, only samples that included
more than 90 percent of eitherthe right or
left lung were used.
  The U.S. Air Force  McClellan Central
Laboratory of Sacramento, California,
analyzed the  lung  and liver samples by
both alpha pulse height analysis (APHA)
and  mass spectrometry.   In  addition,
standards  were checked by the Lawrence
Livermore Laboratory,  Knolls  Atomic
Power Laboratory, and Los Alamos Scien-
tific Laboratory. The EPA, in consultation
with  the  Health Departments of  Colo-
rado and Jefferson County and with the
University of Colorado, decided which
tissue and how many would be collected,
based on  what was then known  about
plutonium distribution in the body from
inhaled plutonium oxide particles.  Be-
cause pulmonary lymph nodes tend to
concentrate plutonium particles from the
lungs, lymph nodes were included in all
lung specimens.
  During  preparation  of samples  at au-
topsy, organs are removed from the body
and  sliced in such  a way that blood or
other fluids seep  out and  are washed
away. Measurements indicated that if the
liver lost about 10 percent of its weight in
fluid seepage, only about 1.5  percent of
resident plutonium was lost  By far the
largest  part of the plutonium burden is
evidently rather firmly fixed to the  tissue
and  does not drain off with the fluid.
Consequently, due to changes in  tissue
fluids at time of death, total organ burden  ^
of plutonium is more meaningful than the  fl
organ tissue concentration alone and
therefore was measured in the study.

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  Only individuals who lived in eastern
Colorado for at least five  years  since
1968, who neither worked at Rocky Flats
nor had been otherwise  occupationally
exposed to plutonium, were included in
the study. Distance from Rocky Flats was
noted for three time periods: the last five
years of life; the period  from 1968  to
1970; and the time of the fire in 1957.
The distribution of the causes of  death
was  compared  to  the  distribution  of
causes of death for the entire state for the
same period of years to  determine the
degree to which the samples were repre-
sentative of the population who died in
Colorado during those same years.

Alpha Spectrometry
  Plutonium samples were analyzed  by
alpha spectroscopy for the presence of
Pu-236, Pu-238, and Pu-239+240. Each
sample was counted on  either a Frisch
Grid detector for approximately  2000
minutes or on a silicon solid state detec-
tor for approximately 3000  minutes.
              Mass Spectrometry
                 Plutonium  samples  were loaded  by
              evaporation on rhenium filaments, placed
              in the source of the mass spectrometer
              and ionized by heating to 1900°C. From
              this, the Pu-240/239 atom ratio and dpm
              were  determined.
                 With plutonium concentrations, organ
              burdens, and isotope ratios in lung and
              liver tissue as the dependent variable, a
              stepwise, multiple  regression  analysis
              was used  to test the data with inde-
              pendent  variables  of age, packyears of
              cigarette smoking,  and  distance  from
              Rocky Flats.   Samples were  analyzed
              separately by sex and for selected areas.

              Results
                 Of  the 519 sample sets obtained for
              the study,  those from 41  control area
              residents have  not  been analyzed for
              plutonium because of budget constraints.
              Ten were excluded from analysis because
              of various problems (See Figure 1.).  For
              the 468  with interviews, 19 were ex-
 cluded from the study because the indi-
 vidual might have been occupationally
exposed to plutonium or had lived in an
area where other plutonium  exposure
could have occurred.
  The remaining 449 sets of samples
included  in the study represented an
aged  population  with females slightly
older than males. The males were much
heavier smokers.   Almost two thirds of
the females were nonsmokers. People
who resided within 50 km east and south
of Rocky Flats during the 1957 fire had a
minutely lower average ratio of Pu-240/
239 in their livers than did those living in
the other study areas, but distance from
Rocky Flats did not show any consistent
relationship for this group.
  Males had a  slightly but significantly
higher average liver burden of plutonium
than females, but they also smoked signif-
icantly more. Liver burden appears to be
low and  weakly related  to any  of  the
variables  in females;  however,  in males,
both age and packyears of smoking were
                                                 519 Autopsies
                                                 22 = Possibly
                                              Otherwise Exposed
                                                 to Weapons-
                                               Grade Plutonium
     2 = Tissue
      Not Yet
     Analysed
              3 = Occupationally
               Exposed, Ruled
              Out of This Study
            46 Not Included in
              Data of Tables
 5 = Tissue
Analysed for
 Plutonium
                         19 Tissue
                       Analysed for
                        Plutonium
                                                                                    512 = Completed
                                                                                      Interviews
                                                          490-"ANOE."
                                                          Autopsied, Not
                                                        Otherwise Exposed
                                                           to Weapons-
                                                         Grade Plutonium
                                                                          41 - "EXTRA-C."
                                                                         Extras from Area C,
                                                                       Tissue not yet Analysed
               449 = "Study Population.
                  Tissue Analysed for
                     Plutonium
                                    473 - Pu 239+240 Analysis
                                  Reported for Liver and/or Lung.
Figure 1.    Breakdown of 519 autopsied individuals.

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usually positively and significantly related
to liver burden.  Nonsmokers and light
smokers  were more  likely  to  have no
Plutonium in their lungs than were heavy
smokers. The data on Pu-240/239 ratio
in lungs tended toward the ratio found in
soil, as a function of distance from Rocky
Flats, but was statistically weak.
  The mean value for concentration of
Plutonium in the lungs of people who had
lived in eastern Colorado was very similar
to the median value estimated by Mclnroy
(1979) for the Colorado population and is
only slightly higherthan the median value
estimated by Fisenne (1979) for a much
younger and healthier population in New
York City.  For liver plutonium concen-
tration, the  mean for eastern Colorado
was  only  slightly higher than the esti-
mated median of both  Mclnroy  and
Fisenne, which could be accounted for by
differences  in age, sex,  and  smoking
habits.
  Results indicated that sex, age,  and
smoking  history were all  more strongly
related to plutonium  burden in the  liver
than distance from Rocky Flats.  Differ-
ences between mean liver  burdens for
male  heavy versus light  smokers,  be-
tween males and females of each group,
and  between older and younger males
were  all  significant   Females  did not
show an age difference in  liver burden
and smoking did  not seem to have an
influence in women.

Discussion
  There are several  possible explana-
tions for finding that  older people have
larger plutonium burdens than do younger
people.   First, the peak  of plutonium
pollution from worldwide fallout occurred
in 1963, after which it dropped during the
next four years by a factor of 15 (Efurd,
1977). Young people  born since then
would therefore have  had considerably
less exposure.
  Second, young people have healthier
lungs in general and  are better able to
eliminate inhaled participates than older
people. Third, from 1950 to 1970, older
people were still  smoking more than
younger people.  Only in  recent years
have teenagers begun to smoke so much
(Last,  1980).  Fourth, since plutonium
was first  used in 1945, an older person
would generally have been exposed to
more  plutonium than  a younger person.
Finally, for growing children, the amount
of air inhaled per unit time increases with
increasing  lung  size, which  increases
with age. All of these factors would tend
to give older people  a  larger plutonium
burden.
  Pu-240/239 ratios in the liver were
significantly higher than  in the  lung.
Additionally, the total amount of pluto-
nium burden  in the liver was about 10
times greater than in the lung.  Both of
these observations are explained by the
fact that retention half-time of plutonium
in the liver is 30 times longer than in the
lung.  Thus, the liver would reflect the
accumulation of plutonium over a person's
whole lifetime and consequently have a
much greater  plutonium burden and a
higher Pu-240/ 239 ratio.
  The results of the study suggest that a
male at the average age of 65.4 years, as
in this study, would have 1.5 times more
plutonium in his liver if he had been an
80-packyearsmokerthan if he had been a
nonsmoker. For a 50-packyear smoker at
the average age, the ratio would be 1.3
times more plutonium. The higher pluto-
nium levels probably do not result from a
higher intake of plutonium among smokers
but from  the  toxic and irritating  sub-
stances in cigarette smoke that  damage
the clearing mechanisms of the lungs,
thereby preventing the natural elimina-
tion of particles.
  Regarding the question  of the Rocky
Flats facility as a source of plutonium, the
results of the  study were not conclusive.
The data suggest that releases of pluto-
nium from Rocky Flats have contributed
to human plutonium burdens east  and
southeast of the site, but the total amount
of plutonium in human tissue is small and
not very different from that observed by
other researchers who  have  studied
people from other locations in the nation.
References
Efurd, D. W., G. L Merrill Jr., J. T. Phelps,
  and K. D. Rosenlof,  1977. Measure-
  ments of Americium and Plutonium in
  the Atmosphere, Published in Transur-
  ancis in Natural Environments,  NVO-
  178, Edited by M. G. White and P. B.
  Puna way, pg. 249.
Fisenne, I. M., M. E. Wrenn and N. Cohen,
  Progress Report to US Dept. of Energy
  on Contract EY-76-S-02-2968 entitled:
  "Determination of Pu 239, 249 Tissue
  Concentrations in  Nonoccupationally
  Exposed Residents of New York City."
  (Ph.D. Thesis of Isabel M.  Fisenne,
  N.Y. Univ. Medical Center.)
Hammond, S.E. 1971.  "Industrial-type
  Operations as  a Source of Environ-
  mental Plutonium" LA 4756, Proceed-
  ings of Environmental Plutonium Sym-
  posium  held  at LASL, 4-5 August
  1971, pp. 25-35.
Hicks, H. G. 1981. Radiochemical Data
  Collected on Events from which Radio-
  activity Escaped Beyond the Borders of
  the  Nevada  Test Range Complex,
  Lawrence Livermore Laboratory Report
  UCRL-52934.
Last J. M., 1980.  Textbook from "Public
  Health and Preventive Medicine" by
  M. Rosenau.  Appleton-Century-Croft
  1980.
Mclnroy, J. F., era/. 1979. Plutonium in
  Autopsy Tissue: A Revision and Up-
  dating of Data  Reported in LA-4875.
  Health Physics  Vol. 37, pp. 1-136.
Seed, J. R., K. W.  Calkins, C. T. Illsley, F.
  J. Miner, and J.  B. Owen, July9,1971.
  RFP-INV-10 Committee Evaluation of
  Plutonium Levels in  Soil Within and
  Surrounding  USAEC Installation  at
  Rocky Flats, Colorado. Prepared under
  Contract AT (29-1 )-1106 for the Albu-
  querque Operations Office U.S. Atomic
  Energy Commission.

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John C. Cobb. B. Charles Eversole, Philip G. Archer, andRoxanna Taggartare with
  the University of Colorado Health Sciences Center. Denver, CO 80262; Deward
  W. Efurd is currently with Los Alamos National Laboratory.
Stuart C. Black is the EPA Project Officer (see below).
The complete report, entitled "Plutonium Burdens in People Living Around the
  Rocky Flats Plant." (Order No. PB 83-137 372; Cost: $22.00, subject to change)
  will be available only from:
       National Technical Information Service
       5285 Port Royal Road
       Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
       Environmental Monitoring Systems Laboratory
       U.S. Environmental Protection Agency
       P.O. Box 15027
       Las Vegas, NV 89114
                                                                                 . S. GOVERNMENT PRINTING OFFICE: 1983/6W-095/1920

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Environmental Protection
Agency
Center for Environmental Research
Information
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