]]]]]]]]]]]]]]]]    THE MYTH OF PLUTONIUM TOXICITY    [[[[[[[[[[ 
                        Bernard L. Cohen              (1/3/1989)
   By Bernard L. Cohen, Department of Physics, University of
          Pittsburgh, Pittsburgh, Pennsylvania 15260.

(From Karl Otto Ott and Bernard I. Spinard, eds. Nuclear Energy
          (New York: Plenum Press, 1985), pp. 355-365)

              [Kindly uploaded by Freeman 10602PANC]

   Plutonium is constantly referred to by the news media as ``the
most toxic substance known to man.''  Ralph Nader has said that a
pound  of plutonium  could cause  8  billion cancers,  and former
Senator Ribicoff  has said  that a  single particle  of plutonium
inhaled into the  lung can cause cancer.   There is no scientific
basis for any of  these statements as I have  shown in a paper in
the  refereed scientific  journal  Health Physics  (Vol.  32, pp.
359-379, 1977).  Nader asked the Nuclear Regulatory Commission to
evaluate  my  paper, which  they  did in  considerable  depth and
detail,  but when  they gave  it  a ``clean  bill of  health'' he
ignored their report.  When he accuses me of ``trying to detoxify
plutonium with a pen,'' I offered  to eat as much plutonium as he
would  eat  of  caffeine,  which  my  paper  shows  is comparably
dangerous, or given reasonable  TV coverage, to personally inhale
1000 times  as much plutonium  as he  says would be  fatal, or in
response to  former Senator  Ribicoff's statement  to inhale 1000
particles of plutonium of any size  that can be suspended in air.
My offer was  made to all  major TV networks  but there has never
been a reply  beyond a request for  a copy of  my paper.  Yet the
false statements continue in the news media and surely 95% of the
public  accept them  as  fact although  virtually  no one  in the
radiation health  scientific community  gives them  credence.  We
have  here  a  complete breakdown  in  communication  between the
scientific  community and  the news  media, and  an unprecedented
display  of  irresponsibility  by  the  latter.   One  must  also
question the ethics  of Nader and  Ribicoff; I have  sent them my
papers  and  written  them personal  letters,  but  I  have never
received a reply.
   Let's  get at  the truth  here  about plutonium  toxicity.  We
begin by outlining  a calculation of the  cancer risk from intake
of plutonium (we refer to it by its chemical symbol, Pu) based on
standard procedures recommended by all national and international
organizations  charges  with  responsibility  in  this  area, and
accepted by the vast majority of radiobiomedical scientists.

   The first step is to calculate  the radiation dose in rem (the
unit of  dose) to  each organ of  the human  body per  gram of Pu
intake.  According to ICRP (International Commission on Radiation
Protection) Publication No. 19, about 25% of inhaled particles of
the size of interest (0.5-5  [micro]m in diameter) deposit in the
lung,  and  60%  of  this  is  eliminated  only  with  a  500-day
half-life.  From this  information and the  known rate and energy
of  [alpha]-particle  emission, we  can  calculate  the radiation
energy deposited  in the lung,  which is  directly convertible to
dose in rem.
   According to ICRP  Publication 19, 5% of  inhaled Pu gets into
the bloodstream from  which 45% gets  into the bone  and an equal
amount collects in the liver;  the times required for elimination
from these are  70 and 35  years, respectively.  This  is all the
information needed  to calculate doses  to bone and  liver in rem
per gram of Pu inhaled.
   If Pu is ingested with food or water in soluble form, the ICRP
estimates that 3 x 10^-5 (30  parts per million) gets through the
intestine  walls  into  the   bloodstream.   From  this  and  the
information given above, calculation of rem to the bone and liver
per gram of  Pu ingested is  straightforward.  In addition, there
is  dosage  to  the  gastrointestinal  tract  calculable  by ICRP
   Once  the dose  in  rem is  calculated,  the next  step  is to
convert this to  cancer risk using the  BEIR Report, the standard
reference  in  this  area produced  by  the  National  Academy of
Sciences Committee  on Biological Effects  of Ionizing Radiation.
It recommends a model  in which there is  a 15-year latent period
following exposure during which there are no effects, followed by
a 30-year  ``plateau'' period  during which  there is  a constant
risk of 1.3  x 10^-6 (1.3  chances per million)  per year per rem
for lung cancer  and 0.2, 1.0, and  0.3 x 10^-6  per year per rem
for bone, gastrointestinal tract and liver* cancer, respectively.
   For  children less  than 10  years old,  these are  divided by
five, and for an older  person, there is a calculable probability
that  death  will  result from  other  causes  before  the cancer
develops.  With this information we can calculate the cancer risk
as a function of  age at intake.  Averaging  over ages, we obtain
the average cancer risk per gram of Pu intake.
*  In  the BEIR  Report,  liver  cancer is  included  among ``all
other'' for which the risk is 1.0 x 10^-6, the value used here is
based partly on other information.
                             TABLE I
           Cancer Doses in Micrograms (Defined as the
                 Inverse of Risk per Microgram)
       Entrance Mode                    239-Pu         Reactor-Pu
Inhalation (dust in air)                 1300              200
Ingestion with food or water          6.5 x 10^6        1 x 10^6
   The  results  are given  in  Table  I for  the  most important
isotope of  Pu, 239-Pu, which  contains 1  curie of radioactivity
for each 16g,  and for the  mixture of Pu  isotopes that would be
commonly found in power reactors, which is 6 times more intensely
radioactive (1 curie in  each 2.5 g).  We  refer to the latter as
``reactor-Pu'' and use it in our discussions where appropriate.
   Table  I shows  the inverse  of  the risk,  which we  call the
``cancer dose.''  For  example, we see that  the risk of inhaling
reactor-Pu is 1/200 per [micro]g,  so if one inhales 10 [micro]g,
he  has  one chance  in  20  of developing  cancer  as  a result.
Another application is  that in a large  population we may expect
one cancer for every 200 [micro]g  inhaled, so if a total of 1000
[micro]g  is  inhaled   by  people,  we   may  expect  5  cancers
(regardless of the number of people involved).
   Estimates of cancer  doses of Pu have  also been derived using
different methods by the British  Medical Research Council in its
report ``The Toxicity  of Plutonium,'' and by  Dr. C.W. Mays (who
developed  some  of  the   important  basic  information  in  his
experiments on dogs)  in a report  published by the International
Atomic Energy  Agency (IAEA-SM-202/806),  and they  agree closely
with  Table  I.   We  see  from  Table  I  that  Pu  is dangerous
principally when inhaled  as a fine  dust.  It is  not very toxic
when  ingested  with food  or  drink  because of  its  very small
probability  of  passing  through the  intestine  walls  into the
bloodstream.   Pu   forms  large  molecules,   which  have  great
difficulty in passing through membranes.
   In addition  to causing cancer,  intake of  plutonium can also
cause genetic defects among progeny in the next 5-10 generations,
but the total number of  eventual genetic defects before they are
bred out is only 20% of the number of cancers.  For simplicity we
restrict our discussion  to cancers, but  the genetic effects can
always be included by applying the 20% addition.
   The  estimates in  Table I  are based  on data  from radiation
effects on humans as analyzed  in the BEIR Report.  These include
Japanese A-bomb  survivors, miners  exposed to  radon gas, people
treated for  various maladies  with radium  or with  X-rays, etc.
None of these  effects were from  Pu -- there  is no evidence for
any  injury to  humans  from Pu  toxicity.   However, there  is a
considerable amount of data from animal studies with Pu, and this
is summarized for lung cancer in  Fig. 1 where the line shows the
estimate from our calculation.  In general the agreement is quite
[Omitted:  ``FIGURE  1.   Data  from  animal   studies  with  Pu,
summarized for  lung cancer.''   The graph  shows 40 data-points,
with confidence intervals, from animal studies (dogs, mice, rats,
rabbits) with a calculated line  over them.  The x-axis, which is
logarithmically scaled,  is labeled  ``Dose to  Lung (millions of
millirem)'' and the y-axis is  labeled ``Incidence of Lung Cancer
(%)''.  Taking representative points  from the calculated line in
the figure, we get: (~0.3  Mmrem, ~1%), (~1.0 Mmrem, ~5%), (~10.0
Mmrem, ~38%), (~11.0 Mmrem, ~65%).  Mmrem: millions of millirem.]
   There has been a great deal  of publicity about the high point
for beagle dogs (the highest point in Fig. 1) but we see that our
curve passes  within the  error bars  given by  the authors.  One
aspect of  the experiment that  is frequently  overlooked is that
the latent period  for development of  the cancers increased with
decreasing dose, and  in fact the dogs  contributing to the point
under discussion developed  cancer rather late  in life.  If this
effect is extrapolated to lower doses, the latent period for most
doses usually considered would greatly exceed life expectancy, so
the  effects  we  derive in  this  paper  would  be substantially

   There have been several criticisms  of treatments like the one
we have given.   The best known of  these is the ``hot-particle''
theory, which  gives greatly  increased effects  (by a  factor of
100,000) due to  the fact that  the Pu is  not evenly distributed
over the lung  but is concentrated in  particles, which give much
higher than average doses  to a few cells.   This theory has been
studied and rejected by the following groups:
   o A Committee  of  the  U.S.  National  Academy  of  Sciencesb
     especially  assembled for  this study  in a  report entitled
     ``Health   Effects  of   Alpha-emitting  Particles   in  the
     Respiratory Tract
   o U.S.   National   Council   on   Radiation   Protection  and
     Measurement (NCRP),  a very distinguished  group composed of
     about 70  in our  nation's leading  radiobiomedical research
     scientists, in NCRP Publication No. 46
   o British  Medical  Research  Council  in  ``The  Toxicity  of
   o U.K. National  Radiological Protection  Board in  its Report
     R-29 and Bulletin No. 8 (1974)
   o U.S. AEC in  a very elaborate  study, WASH-1320, authored by
     three of the world's leading researchers on Pu toxicity
   o U.S. NRC in Federal Register, Vol. 41, No. 76
   o U.K. Royal  Commission on  Environmental Pollution  -- Sixth
     Report -- Nuclear Power and the Environment
   One easily understood aspect of these criticisms is that there
were about 25  workers at Los Alamos  who inhaled varying amounts
of Pu about  30 years ago, and  according to the ``hot-particle''
theory  each  should  have experienced  about  200  lung cancers,
whereas  there  have been  no  lung  cancers as  yet  among them.
According to our estimates in Table I, there is a 40% chance that
one of them would  have had lung cancer,  so this is experimental
evidence that Table  I does not  grossly underestimate the cancer
risk from  Pu intake.   [For more on  the Los  Alamos workers see
George  L.  Voelz,  Robert S.  Grier,  Louis  H.  Hempelmann, ``A
37-Year  Medical  Follow-Up Of  Manhattan  Project  Pu Workers'',
Health Physics, Vol. 48, No. 3 (March 1985), pp. 249-259.]
   Another criticism of the ``hot-particle'' theory is that there
are experiments  on animals in  which two groups  were exposed to
the same total amount of  Pu but in one of  them it was much more
in the form of hot particles  -- and that group experienced fewer
cancers.  It was also  pointed out that particles  in the lung do
not stay  in one  place but are  constantly moving  about so that
their exposure does not fall on only a few cells.
   After   these  rejections   of  the   ``hot-particle''  theory
appeared, John Gofman, a former  research scientist who has spent
the past several years as  the full-time leader of an antinuclear
organization,  came  out  with a  new  theory  ascribing enhanced
toxicity  to Pu.   His  paper was  not  written for  a scientific
journal but was  inserted in the  congressional Record by Senator
Gravel.  His basic  premise was that  smoking destroys the cilia,
the  fine  hairs  that  stop  dust  particles  from  entering the
bronchial region -- this much was well established -- and that Pu
particles therefore remain  in that region for  a very long time,
allowing their radiation to cause bronchial cancers.  This allows
him to ignore the  animal data as animals  do not smoke.  He also
manages to  explain the  lack of  lung cancers  among the  25 Los
Alamos workers  by a  combination of  four improbable hypotheses,
the failure of any one of which would destroy his theory.
   There have  been at  least seven  individual critiques  of the
Gofman theory.  Perhaps the most  telling criticism is that there
was a  series of  experiments at New  York University  in which a
number  of  graduate  students  inhaled  a  controlled  amount of
radioactive dust and the rate at which this dust was cleared from
the bronchial region was directly determined by placing radiation
detectors over their chests and measuring the radiation intensity
as a function of time.  It was found that there was no difference
between smokers  and nonsmokers, and  the experimenters concluded
that smokers  do more  coughing and  have increases  mucous flow,
which  compensates for  their lack  of cilia.   In fact,  if dust
accumulated  in the  bronchial region  of  smokers in  the manner
postulated by Gofman,  their bronchial tubes  would be completely
closed and they would die by suffocation.
   There were many more weak points  in the details of the Gofman
paper.  He misuses the BEIR  Report, he miscalculates the area of
the bronchial  region by a  factor of 17  and thereby incorrectly
increases the toxicity  by that factor, he  misuses the ICRP lung
model, etc.   He even  suggests that  the great  increase in lung
cancer in recent  years may be  due to Pu,  but this increase has
been steady since the 1930s whereas Pu-induced cancers should not
have occurred  until 1960.   Moreover, the  lung cancer increases
have been in areas with chemical industry and high air pollution,
and there has been no increase  in areas downwind from the Nevada
test site where Pu would have its maximum effect.
   A  relatively  less  publicized  attack  on  the  conventional
approach  to  evaluating  Pu  toxicity  is  the ``warm-particle''
theory of Edward Martell.  He hypothesizes that natural radiation
is one of the principal causes  of lung cancer, but this idea has
not been accepted by the cancer research community.
   K.Z.  Morgan   has  proposed  that   the  relative  biological
effectiveness (RBE) for Pu in bone might be 250 times larger than
the  usual  value.   C.W.  Mays,  on  whose  experiments  much of
Morgan's  hypothesis  is  based,  reanalyzed  Morgan's  work  and
concluded that if his approach is correct, the increase should be
only by  a factor  of 10.   There is  experimental information on
this from  some supposedly  ``terminally ill''  patients injected
with Pu  in 1945-46  to study Pu  metabolism.  Four  of these are
still alive and one who was injected with a rather large quantity
died of unrelated causes only in 1968.   If the RBE of Pu were 10
times the present value, there is  a better than even chance that
one of these  five would have  gotten bone cancer,  but none did.
As  our  calculated  inhalation  effects  are  dominated  by lung
cancer, a factor  of 10 increase  in bone cancer  risk would only
double the total inhalation risk.
   S.M.  Wolfe, and  employee  of a  Nader-sponsored  group, drew
far-reaching conclusions  from the fact  that 11 of  the first 30
deaths in the  US Transuranic Registry (a  registry of people who
have worked with plutonium)  revealed cancers on autopsy, whereas
based on  listed cause-of-death for  all U.S. males,  only 6.2 of
each  30  deaths is  from  cancer.   His paper,  which  was never
published  in  the  scientific  literature,  received  very  wide
publicity  in  the  news  media.   However,  it  turned  out that
autopsies  were done  preferentially on  people  who had  died of
cancer, and  that explained the  entire effect.   In addition, it
was pointed out that Pu is expected to cause cancers of the lung,
bone, and liver, whereas among the 11 cases there were no bone or
liver cancers, and less than  the expected number of lung cancers
for a normal  population.  Needless to say,  the news media never
bothered to report that the Wolf  paper was based on an incorrect
   In  evaluating all  of the  criticisms  outlined above,  it is
important to realize that they are actively considered every year
by a  committee of  the ICRP and  that they  have repeatedly been
rejected.  Likewise, the EPA, which has jurisdiction in the U.S.,
studied the matter  and decided not to  modify its standards.  No
standard-setting or official study group in any country has given
credence to any of these criticisms of the standard procedures we
used in deriving Table I.

   It is clear from  Table I that Pu  is dangerous principally as
an inhalant, so  we now consider the  consequences of a dispersal
of Pu powder in a populated area.  The calculations are done with
a standard  meteorological model, in  which the  dust cloud moves
with the wind dispersing in the downwind, crosswind, and vertical
directions.   Meteorologists   have  determined   the  extent  of
dispersal  as  a  function   of  wind  velocity  and  atmospheric
stability.  Figure 2 shows  the results of calculations assigning
the  atmospheric  stability  most  characteristic  of  each  wind
velocity.  This is  different between day  and night, so separate
curves are given for each.
   These  curves give  the area  within which  various fractions,
q/Q, of the dispersed Pu are taken  in by a person inhaling at an
average rate.  For example, we see from Fig. 2 that for a typical
daytime 8 m/sec wind  velocity, only in an area  of 500 m^2 is as
much as  10^-6 (one  millionth) of  the dispersed  Pu inhaled.  A
typical  city  population  is 10^-2  people/m^2,  so  there would
typically be about  5 people in this  area.  Similarly, from Fig.
2, about  60 people would  inhale 10^-7, 700  people would inhale
10^-8, etc. of the dispersed Pu.
   As we know  the cancer risk  per microgram of  Pu inhaled from
Table I, it  is straightforward to calculate  the total number of
cancers expected per gram of  Pu dispersed.  When corrections are
applied  for  the fraction  of  typical  Pu powders  that  are in
particles of  respirable size,  the efficiency  of dispersal, the
protection  afforded  by being  inside  buildings,  and decreased
breathing rates at night, the result  is that we may expect about
one eventual cancer for  every 24 g of  Pu dispersed, or about 19
fatalities per pound.
   If there is a warning, as  in a blackmail scenario, people can
be instructed to breathe through a folded handkerchief or a thick
article of clothing, with a resulting decrease in fatalities to 3
per pound dispersed.
   Eventually, the Pu  settles to the  ground but it  may then be
blown up  by winds.   Meteorologists have  also developed methods
for    calculating    these     effects    (``deposition''    and
``resuspension'').   Within  the first  few  months,  this causes
about one-third  as many cancers  as inhalation  from the initial
cloud.  Beyond this time period, resuspension is of much less and
continually decreasing importance  as the Pu  becomes part of the
[Omitted: ``FIGURE  2. Area  over which  the ratio  of inhaled to
dispersed Pu has values shown  for q/Q versus wind velocity under
typical  day  and night  atmospheric  conditions.''   The x-axis,
which  is  logarithmically  scaled,  is  labeled  ``Wind Velocity
(meters/sec)'' and the y-axis is labeled ``Area (meter^2)''.]
   Of course, 239-Pu lasts for tens of thousands of years, so let
us  consider its  effects  over this  time  period.  We  know the
amount of uranium  in soil and we  know now how  much there is as
dust in the air, so we can  estimate how much is inhaled per year
-- it calculates out to be 1.3 x  10^-11 of that in the top 20 cm
of soil.  If  this factor is  applied to the  Pu after it becomes
part of  the soil,  we find  that over  the 25,000-year half-life
there will  eventually be  about one  fatality per  2500 g  of Pu
dispersed.   Thus,  we  see that  the  long  half-life  is almost
irrelevant; nearly all of the  damage eventually done occurs very
soon after dispersal.
   A summary  of all  these effects of  Pu dispersal  is given in
Table II.  It also  includes plant uptake into  food.  There is a
great deal  of information  on uptake of  Pu by  plants both from
laboratory   experiments  and   from   several  areas   where  an
appreciable amount of Pu has gotten into the soil from bomb tests
or from various  research activities.  Plant  uptake is small for
the same reason that Pu does not easily pass through the walls of
the intestines --  it forms large molecules,  which do not easily
pass  through membranes.   From Table  II we  see that  the total
eventual effect of Pu dispersal in  a city is one fatality per 18
g dispersed without warning, or 25 fatalities per pound.
                            TABLE II
                 Summary of Fatalities per Gram
                     of Reactor-Pu Dispersed
         Inhalation from cloud           0.042 (1/24)
         Resuspension                    0.014
         Long Term                       0.0004 (1/2500)
         Plant uptake into food          0.002
              Total                      0.058 (1/18)

   The  fear is  sometimes expressed  that  the world  may become
``contaminated'' with 239-Pu.  To  evaluate this potentiality, we
calculate that  if all  the world's  present electric  power were
produced  by fast  breeder reactors  in an  equilibrium situation
where Pu is consumed as fast  as it is produced, the total amount
of 239-Pu existing in the world would be 2 x 10^8 curies.
   By comparison, the  radium (226-Ra) in each  meter of depth of
the earth's crust is 1.2 x 10^9 curies, so there is as much Ra in
each 17 cm of depth as there  would be 239-Pu in the whole world.
For ingestion,  Ra is 40  times more  toxic than Pu  as it passes
through  the  intestine  walls  much  more  easily.   For  direct
inhalation, Ra  is less  hazardous than  Pu, but  it serves  as a
source of radon gas,  which comes up out  of the ground and mixes
with the  air we breathe,  and therefore is  a serious inhalation
hazard, so  as material  on the ground,  Ra is  a 40-fold greater
inhalation hazard than Pu.
   Thus,  as  a  long-term hazard  either  for  ingestion  or for
inhalation,  Ra  is 40  times  worse  than Pu;  the  total  Pu in
existence  for  an  all-breeder power  system  would  then  be as
dangerous as the Ra in each 4  mm of our soil.  Of course, nearly
all of  this Pu  would be in  reactors or  in other  parts of the
nuclear industry, well isolated from the environment.
   There is now a legal  requirement on the allowable releases of
Pu from nuclear plants, which is such that if all U.S. power were
nuclear and derived from fast breeder reactors (they use the most
Pu), the  total releases  would be about  0.6 g/year.   If we use
table II,  this would predict  an average  of 0.03 fatality/year,
but that would be valid only if nuclear plants were in cities; as
they are not,  the expected effects  are about 10  times less, or
one fatality in 300 years.
   Some perspective on this problem  may be obtained by comparing
the 0.6 g/year tht [sic] may  some day be released by the nuclear
industry with  the amount  of Pu that  has been  dispersed in the
atmosphere  in  nuclear  bomb  tests,   which  is  5  million  g.
Estimates on the same basis that we have been using predict about
200 U.S. fatalities to  date from Pu releases  in bomb tests, and
4000  in  the  world.   It  also  predicts  about  200 fatalities
worldwide from  the reentry  burn-up in  1964 of  a space vehicle
carrying a SNAP-9A 238-Pu-powered energy source.  It is important
to  keep in  mind that  all of  these estimates  are theoretical.
These is no direct evidence for Pu toxicity having caused serious
injury to any human being, anywhere, ever.
   The reason why the legal  requirement on plutonium releases is
so stringent is not  because Pu is so  dangerous, but because the
technology is available for keeping the releases that low, and in
fact this technology is very  close to present practice.  Pu dust
particles tend to stick to each other and their containers, so Pu
is not  easily dispersed.  It  is also very  readily collected on
filters; anywhere Pu powder is used, the air is exhausted through
filters, which catch  all but about  one part per  billion of the
dust suspended in air.
   Of  course,  the  control  measures  are  expensive  and  they
increase the cost  of nuclear electricity.   As previously noted,
the reason they are required is not because Pu is so dangerous --
one fatality  every 300  years is  surely a  trivial problem when
burning coal, our  only viable alternative  to nuclear energy, is
killing 10,000  people every year  with its air  pollution -- but
because the public  is afraid of  plutonium.  Ralph Nader, former
Senator Ribicoff,  John Gofman,  and their  like have  done their
work well,  and the  public is paying  the price  in its electric
   One often hears  that in large-scale production  of Pu we will
be  creating unprecedented  quantities  of a  poisonous material.
Because Pu is dangerous principally as an inhalant, we compare it
in  Table  III  with  quantities  of  other  poisonous  inhalants
produced in  the U.S.   We see that  it is  relatively trivial by
comparison.  Moreover, it  should be noted that  Pu is not easily
dispersed  whereas  the  others   are  gases  and  hence  readily
dispersible.  Of course, Pu released to the environment will last
far  longer   than  these   gases,  which   would  be  decomposed
chemically, but  recall from  our earlier  discussion that nearly
all of the damage done in Pu dispersal is by the initial cloud of
dust; all  of the later  resuspension and the  thousands of years
spent in the soil  do far less damage.  It  is thus not unfair to
compare Pu with the poison gases,  and we see from Table III that
it will always be far less of a hazard.
                            TABLE III
        Lethal Inhalation Doses Produced Annually in the
                         U.S. (x 10^12)
   Chlorine                                               400
   Phosgene                                                18
   Ammonia                                                  6
   Hydrogen cyanide                                         6
   Pu if all U.S. power were from fast breeder reactors     1
   It is often argued  that there is a great  deal we do not know
about  Pu  toxicity.   While  this  may  be  true,  one  would be
hard-pressed to name another public  health issue that is as well
understood and controlled.  Surely it  would not be air pollution
from  burning  coal, which  is  a  million times  more  serious a
problem.  Surely it is not food additives or insecticides or such
[the dangers from these have  also been greatly exaggerated] that
may well be  doing real harm  to our health.   Pu hazards are far
better understood than any of these, and the one fatality per 300
years they may someday cause is truly trivial by comparison.
   In spite of the facts we  have cited here, facts well known in
the scientific  community, the  myth of  Pu toxicity  lingers on.
The  news media  ignore us,  and prefer  to continue  scaring the
public at every opportunity.  They don't recognize the difference
between political issues on which everyone is equally entitled to
an  opinion,  and  scientific issues,  which  are  susceptible to
scientific investigation and proof.  The myth may linger forever.

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