How toxic chemically is plutonium (Pu), neglecting the radioactive damage?
The toxicity is primarily due to radioactivity and to absorption by the body, where that radioactivity can act internally. There is, &quot;significant deposition of plutonium in the liver and in the &quot;actively metabolizing&quot; portion of bone,&quot; according to Miner and Schonfeld.
Many $\ce{Pu}$ isotopes are primarily alpha-emitters, with &quot;high energy radiation with low penetration and thereby requires minimal shielding. A sheet of paper can be used to shield against the alpha particles emitted by plutonium-238,&quot; from Wikipedia. The risk of holding a small amount of plutonium, if it is sealed inside almost any container, is negligible, because the the heavy, positively-charged alpha particles are stopped by the container in a very short distance.
By that same token, when absorbed, the plutonium migrates to rapidly dividing liver tissue and bone's hematopoietic cells. The alpha particles are stopped in a very short distance, depositing all their energy in the few nearest cells and massively interfering with cellular reproduction. Small amounts can cause various types of cancer, such as leukemia, a cancer of the previously-mentioned blood cell producing tissues.
That said, plutonium is not quite as toxic as one might think: &quot;The U.S. Department of Energy estimates that the lifetime cancer risk from inhaling 5,000 plutonium particles, each about 3 µm wide, to be 1% over the background U.S. average... no human being is known to have died because of inhaling or ingesting plutonium, and many people have measurable amounts of plutonium in their bodies.&quot;
Perhaps what Rhodes means by &quot;not that radioactive&quot; is that the radiation from plutonium is not very penetrating. The isotope used in nuclear weapons, 239Pu, has a half-life of about 24,000 years, comparable to radium, or to 231Pa. If I've done my math  correctly, one mole of 239Pu, about 6e23 atoms, with  half-life of 8e11 seconds, should emit about 400,000,000,000 alpha particles per second. Of course, if it were a sphere, most of those particles would be absorbed inside the mass of metal, releasing energy as heat. However, spread through a human body, each particle has a much greater chance to cause damage. And 238Pu, used in radioisotope thermoelectric generators, is far more radioactive!