THE PLUTONIUM GRABBER

Plutonium is singled out as a hated target by the likes of Yelena Koldikott (AtE Oct 80) and George Wald, who wage a ferocious campaign against it with blatantly false statements about its toxicity.

Yes, plutonium is toxic and can be dangerous, especially when its dust lodges in the lung, though even then it is not as dangerous as some natural substances that can get into the lung (radium, for example). We have previously written about the 25 workers of the Manhattan Project who received 25 times the permissible lung burden, and who either died of causes unrelated to plutonium, or are still in good health. We have also met a man who was in a bad accident involving plutonium in the armament industry in the late 60's; he, too, carries a multiple of the permissible burden in his lung, but doctors will not operate it out, because the operation would be more risky than the plutonium in the lung. (He still works at the plant where he had the accident, but would not let us print his name or picture, explaining "People often treat me as a leper when they find out that I am full of plutonium.")

Plutonium is an alpha emitter, which means that (unlike radium and other radionuclides) it cannot hurt anybody at a distance with its radiation; it must first get into the body. If it is eaten, it is, like lead and other heavy metals, bone-seeking and toxic. If it gets as far as the bone marrow, it is difficult to remove; but a way has now been found to remove it from other organs, such as spleen and liver, where it usually lodges, forming a strong ionic bond with body proteins.

A team of Lawrence Berkeley Lab scientists led by K. Raymond and F. Waite has produced a chemical named LICAM-C, which has removed 70% of the plutonium injected into laboratory mice, and it is believed that more can be removed with repeated doses without toxic side effects.

Plutonium has many properties similar to iron, and there is a group of chemicals known as chelates (pronounced "keelates;" the name comes from the Greek for crab's claw), whose molecules will wrap themselves round certain elements and grab those elements' ions with chemical pincers. Iron chelates are used by bacteria to absorb iron, and prescribed by doctors for patients who have too much iron in their systems.

The search started with such iron chelates, and after extensive testing, LBL scientists finally came up with a chelate that tightly binds plutonium (but not other minerals essential to the body such as calcium, iron or zinc), and that has a molecular weight low enough to pass through the kidneys so as to be excreted.

Plutonium poisoning is, of course, among the world's rarest afflictions. But the study of plutonium chelates is important for removing plutonium from reactor wastes.

Why? Because its halflife is almost 24,000 years? No: A long halflife means a low level of activity, or the substance would spend itself sooner. Elements that don't decay at all (like arsenic) last forever, because they don't radiate themselves away; they have a halflife of infinity.

The reason is quite different: Plutonium is recovered for its own sake.

When silver is recovered from photographic lab waste, nobody suspects that this must be done to make the sewage less hazardous; but plutonium has been so maligned that few people realize that it takes far more effort and expense to produce an ounce of plutonium than an ounce of gold.