Re: Pu Toxicity

[FRAMEP@ORAU.GOV]

          We (us nuclear guys and gals) are the ones
          responsible for the claim that Pu is the most toxic material
          there is. The claim was made during WWII to scare workers
          into following safe working procedures and (probably) to
          obtain more money for the Pu project. Seaborg once said that
          until 1943 (when the ORNL graphite reactor came on line to
          produce it) Pu was so scarce that they couldn't afford to
          have folk to go around ingesting the stuff.

          We should be careful that we don't downplay
          the risk of Pu when we try to put the risk into
          "perspective" for the public. The public will turn against
          us very quickly if they think they are being misled.

          The table cited in previous posts (sorry for not including
          it here) must be used carefully. It refers to toxicity i.e
          acute deaths from plutonium ingestion and inhalation - hours
          to days later (25 mg inhaled or 500 mg ingested). The
          problem is that the other things on the table we are
          comparing Pu with don't have the same longer term risks that
          plutonium does. Toxicity is not the whole story.  I' not an
          expert and am ballparking here: something like 2 mg inhaled
          Pu might lead to death within one year from respiratory
          failure. And this ignores cancer!  Cancer makes Pu an even
          greater risk (somebody please check the following numbers):

          Deaths from 0.1 mg Pu-239 (0.0001 g) inhaled: 0.1 mg =
          0.0001 g x 0.062 Ci/g = 6.2 E-6 Ci x 3.7 E10 Bq/Ci = 229,400
          Bq.  The EDE for Pu-239 inhaled is ca 1 E-4 Sv/Bq so 0.1 mg
          inhaled gives 229,400 Bq x 1 E-4 Sv/ Bq = 23 Sv or 2300 rem.

          Given that the risk of death is ca 5 E-4/rem,
          the risk of death from 0.1 mg Pu-239 inhaled would be 2300
          rem x 5 E-4/rem  = 1. Thats high! For Pu-238, the risk of
          cancer per mg would be even greater, roughly 300 times that
          of Pu-239 per mg, because of its higher specific activity.

          Paul Frame  framep@orau.gov
          Oak Ridge Associated Universities.