In the spring of 1912 an enterprising man of vision from Chicago named John P. Nagel bought the land out from under Leib and commenced developing it as a mineral excavation site. Nagel proudly owned a mining operation that employed several men, housed in a dormitory built from local materials, and photos show him standing over a production table heaped with big chunks of ore. Within a few years the easy pickings in the mine played out, it was abandoned, and the mystery hole in the Ozarks once again slipped into obscurity.
It is clear that Leib and Nagel saw a connection between the inexplicable burns on Bill Henry after his cave adventure and later tabloid descriptions of burns on lab technicians from handling radium. They reasoned that the hunting trio had stumbled upon a radium mine.
This account of the first documented radiation injury requires clarification.[8] For one thing, there is no such thing as a radium mine. All the radium-266 that may have been in existence when the Earth was assembled from interstellar debris quickly disappeared, in astronomical terms, as its half-life is only 1,600 years. However, there is always a very small supply of radium in the Earth’s crust, because it is a decay product of uranium, which has been on this planet from the beginning. The radium also undergoes radioactive decay into radon gas, and an equilibrium exists between production and loss. Radium is therefore available in uranium deposits in trace amounts. Many tons of uranium must be processed to extract a few milligrams of radium-266. Note that none of the many minerals known to contain uranium are shiny, metallic, or particularly interesting looking. Uranium metal does not exist in nature, but if it did, it would quickly turn dark gray and soak up every oxygen molecule that passed its way.
Mining uranium in the confines of tunnels is, of course, dangerous without safety measures, but the danger is slow to affect the human body. Breathing the radioactive dust and gas in a mine for decades can cause lung cancer, but it can take 20 years for it to metastasize. Just standing in a uranium mine, leaning against the wall, or taking a nap in a dark corner will not cause anything. No person before or since has developed radiation burns on skin from being in contact even with pure uranium. It certainly gives off alpha, beta, and gamma radiation plus a chain of radioactive decay products, but the process is so slow, it cannot immediately affect living tissue. How then is this incident explainable? In 1879 there wasn’t even enough knowledge to make up such a story.
Henry, Dempsey, and Boyceyer had ventured into an undisturbed series of caverns lined with uranium ore of exceptional purity.[9] There was no cross-ventilation of the rooms, and radon-222 gas, with a half-life of 3.842 days, had been free to collect, undisturbed, as it seeped out of the walls, floor, and ceiling. It is a heavy, noble gas, not interacting chemically with anything, but emitting powerful alpha particles and associated gamma radiation. The back chambers of the cave may have collected radioactive gas for millions of years, as it displaced the cover gas of atmospheric nitrogen and some oxygen, again reaching an optimum equilibrium state between production and loss by radioactive decay. There was no mention of anything alive in the cave, and the apparently clean floors indicated that no bats had ever lived in there.
Radon-222 is the product of the decay of radium-226, and is, indirectly, a product of the slow decay of uranium-238, the predominant isotope in uranium ore. The rough walls of the cave gave a tremendous surface area of radioactive ore, and the loss of radon by rapid decay was slightly less than the production of radon by radium decaying at or near the inner surface of the cave. Radon production occurring significantly below the surface of the ore would not contribute anything, as the gas would decay into something else before it had a chance to diffuse to the surface. Without the abnormally high production rate due to the large surface area, the radon leaking into the cave would have dissipated faster than it was made, and trivial amounts would have built up. When the hunters advanced deeper into the cavern, they were breathing it instead of normal air. The lack of oxygen made them hallucinate, pass out, and talk crazy.
Uranium or thorium, regardless of how pure or how close to the skin or the length of the exposure, cannot produce the burns described on Henry. These natural materials are simply insufficiently radioactive, and the radium traces must be laboriously extracted and concentrated to start doing harm. The concentrated radon, however, in this highly unusual situation, could have done it. Why it seemed to affect Henry most severely is probably because he was the most aggressive explorer of the three, squeezing through every narrow passage, and perhaps the clothing he wore contributed to the effect. It was probably heavier or had more layers than what the other two explorers wore. The radon gas, not reacting chemically with anything, was free to diffuse into his clothing, subjecting him to alpha and gamma radiation as it decayed, but this would not explain his burns. It is also possible that Henry was the one of the three explorers who was unusually sensitive to radiation.
The decay products of radon-222 are a complex chain of 11 radioactive isotopes, from polonium-218 down to thallium-206, before it ends at stable, non-radioactive lead-206. Half-lives range from 0.1463 milliseconds to 22.3 years. All the radon decay products in the 11-member chain are solids, even at the atomic level, and they would definitely stick to his clothing and his skin, with each product extremely radioactive. As Henry squeezed through the cave, scrubbing the wall and standing in concentrated radon gas, his clothing was loaded up with radon decay products in the form of fine dust. Over the next few days, being portaged to the hospital in Carthage, he could have been hit with eight beta rays coming from each radon atom. His lungs started to clear as soon as he got into fresh air, but his clothing was heavily contaminated.
Alpha radiation consists of a large clump of nuclear particles, or nucleons, and it represents a sudden, radical crumbling of an atomic nucleus, just happening out of the blue. The resulting alpha particle is a helium-4 nucleus, complete, and when hurled at anything solid it can cause damage on a sub-atomic level.
The beta “ray” or “particle” (either term is correct) is actually an electron or its evil twin, the positron, banished from a nucleus and hurtling outward at high speed. It is the result of the sudden, unpredictable change of a neutron into a proton or a proton into a neutron down inside an atomic nucleus. This decay event also completely changes the atom’s identity, its chemical properties, and its place in the hallowed Periodic Table of the Elements. Meanwhile, the traveling beta particle, while much lighter than the alpha particle, is still an “ionizing” radiation. If it is a particularly energetic beta example (they come in all strengths), it can hit an atom that’s looking the other way with enough force to blow its upper electrons out of orbit, break up molecular bonds, and bounce things around, causing the matter in its way to heat up. On skin this effect turns up as a burn, or a reddening of the surface, just like you get from an aggressive tanning booth.
The gamma ray, yet another form of nuclear radiation, is an electromagnetic wave similar to ultraviolet light or x-rays, only it is far more energetic. A gamma ray of sufficient energy can penetrate your car door, go clean through your body, and out the other side, leaving an ionized trail of molecular corruption in its path. It is the product of a rearrangement or settling of the structure of an atomic nucleus, and it naturally occurs often when a nucleus is traumatized by having just emitted an alpha or a beta particle. Gamma rays can be deadly to living cells, but, unlike the clumsy alpha particle, they can enter and leave without losing all their energy in your flesh. It’s the difference between being hit with a full-metal-jacketed .223 or a 12-gauge dumdum. Both hurt.
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Technically, the initial radiation injury happened the first time someone was sunburned, an incident which is lost to prehistory. The case of Bill Henry in the cave is, however, the first that I have found where a person may have suffered an acute radiation injury of local nuclear origin. Chronic radiation sickness has been documented since the early 15th century, when copper miners in the Scheesberg area of St. Jaochimsthal, Bohemia, began complaining of a mysterious respiratory illness. Miners were dying at an alarming rate of the
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Or had they? The minerals described in the garbled accounts really don’t seem like uranium-bearing ore. It actually could be a description of some sort of thorium-phosphate crystal or a pure form of monazite mineral. Thorium has a slow alpha-beta-gamma disintegration much like uranium, resulting in radium-228, which is a fairly active beta-emitter. Also in the decay chain are radium-224 and radon-220, both alpha emitters. The tailings from the old Pea Ridge iron mine in Washington County, Missouri, are now seen as a source of thorium, which could be a potential reactor fuel. However, in 2009 John Gustovson, a geologist, discovered what could be one of the “biggest deposits of undiscovered uranium in the U.S.” in southern Missouri.