Th more toxic than Pu???

["Jesse H. Coleman" <radshoals@airnet.net>]

RADSAFERS,

Surely I have made a mistake, but it looks to me like good old Th-232 is
5 times more toxic that any isotope of Pu.

The inhalation ALI for Th-232 is 4E-5 MBq (0.001 micro Ci), Class W.

The lowest Inh ALI's for any Pu isotopes are 2E-4 MBq (0.006 micro Ci)
for Pu-239 and 240, Class W.

The lower the ALI, the more toxic the isotope.  Yes?  Then Th-232 is 5
times as toxic as any type of Pu.

Notice that the half life of Th-232 is 14,000,000,000 years, lots
longer than any isotope of Pu.

According to my calculator and using 1.8 g/cc as a soil density, there
is over a ton of Th-232 in the upper inch of every sq mi of soil in
the the world.  (NCRP 94, Table 4.3, concentration of Th-232 in average
contnetal upper crust (dirt) is 10.7 ppm, mass ratio)

Thorium also goes to bone, gonads and all other tissues (Fed Guidance
Report No. 11).

OK - Plutionim is among the most deadly things on Earth.  Thorium is
5 times as "deadly" as Plutonium.  There are tons of the stuff around
us and all our ancestors.  All life should have been extinguished
long ago.

Since I am now retired, this is for sure the official opinion of my
employer.

Have a happy holiday.

Jesse Coleman