From the vault: Elemental bio-imaging of thorium, uranium, and plutonium in tissues from occupationally exposed former nuclear workers

750px-HEUraniumCIn 2010, with my colleagues at the University of Technology, Sydney and Washington State University (Go Cougars!), I looked into how former workers in the nuclear weapons manufacturing industry had an extra consideration when it came to safety on the job: these folks, every day, were handling some of the most dangerous materials on the planet: plutonium, uranium and all the other nasties used to build atomic weapons. Like any other laboratory job, there was always the risk of workplace incidents, but factor in radioactive materials that have a half-life of over 700 million years, and the consequences of a knocked-over beaker become even more dire.

In this study, we looked at 4 individuals who each worked in nuclear weapons plants at the height of the Cold War, a time when the global nuclear weapons stockpile numbered 31,225 individual warheads, enough to incinerate the world’s surface several times over. Each person, who was part of the United States Transuranium and Uranium Registries, was involved in what was considered a ‘minor’ exposure arising from a workplace incident. The USTUR, which is charged with studying the health of workers in the weapon manufacturing (and now decommissioning, as the world’s stockpile slowly reduces) industry, collected tissue from these participants after their passing, which, amazingly, were all the consequence of health issues separate to radiation. You can read about their stories after the jump.

Case 0407 worked in the Rocky Flats Plutonium Fabrication Plant in Colorado, USA for nearly 20 years. Halfway through his tenure there, we was involved in a fire whilst inside a large glove box, and was exposed to a significant amount of refractory, or insoluble plutonium, primarily via inhalation. He was treated with chelation therapy, but as most plutonium was retained as particles in his lungs, this was ineffective and he was reassigned to non-plutonium duties. Amazingly, he passed away at over 90 years of age nearly half a century later. He donated his body to the USTUR, and we examined lymph nodes from his neck, which would have been a primary site of drainage from his exposure incident.

fig 1 pluIncredibly, we found that his paratracheal lymph nodes contained small particles of plutonium-239 and 240 (on the bottom row of the picture above), which he carried with him for decades after the accident. Even more amazing, this registrant passed away from heart failure, and to our knowledge had no recorded complaints regarding his neck and throat. Interestingly, when we examined his lungs, we found no similar plutonium particles still handing around.

Case 0303 had a less dramatic, but equally dangerous exposure when he punctured a glove and cut his finger on equipment contaminated with plutonium whilst working at the Hanford facility in Washington state in 1968. Unlike Case 0407, chelation therapy was successful in assisting his body in removing the soluble plutonium through the normal routes of urine and fecal excretion. Like 0407 though, this registrant continued to live a lengthy and healthy life to the age of 87, which might explain why we found no trace of plutonium left in his lymphatic tissue.

Case 0246 also worked at the Hanford site, and he was involved in a particularly nasty incident in 1976, when a piece of equipment exploded and showered him with acid and as much as 100 grams of americium. Americium, for those that don’t know, is used in the common household smoke detector, but in much smaller amounts (check out this great HowStuffWorks page on how smoke detectors, well, work). Case 0246 was exposed to the equivalent of 500,000 smoke detectors-worth of americium.  Now, americium isn’t nearly as radioactive as plutonium (would we trust it to wake us up if our house is on fire otherwise?), but that much can’t be healthy. Nor, of course, was the acid shower Case 0246 received, which, as it turns out, was probably much more harmful.

fig 5 amConsidering inhalation was probably the most likely (and potentially dangerous) route of exposure, we examined Case 0246’s lungs, can found no evidence of americium, only the odd particle of thorium or uranium, which we found was pretty much consistent in anyone working in a nuclear plant. It seemed the chelation therapy also worked in this case, and Case 0246 survived this ordeal and lived to be over 70 years old.

As I said, we found that uranium was a pretty common feature in every sample we looked at. As much as some people might not want to admit it, uranium is a natural element, and we’re all exposed to it in very, very, very low levels in our day-to-day existence. However, Case 1060 really made us look twice. This participant worked at the Hanford site, but a decade or so earlier, from 1948. This was a time when scientists were still coming to terms with the gravity of the atomic age, with things like long term health effects hardly a consideration. Case 1060 worked in the uranium melt plant for 2 years, and was exposed to massive amounts of uranium on a daily basis. Record keeping and OH&S wasn’t quite what it was now, but routine urine analysis showed that, along with his daily dose of chronic uranium exposure, he also has a single high exposure incident in 1948.

uranium fig 6What’s interesting here is that Case 1060’s lymph nodes contained a lot of uranium. Compared to the other cases, this worker had around 40 times the uranium we found typical of a worker in the decades following. Again though, it didn’t seem to effect his quality of life; he lived until 2008, when he passed from a stroke.

Now, it’s important to note that nothing about this study should be considered an endorsement for the nuclear weapons industry as a ‘safe workplace’, nor should it distract from the scientifically proven harmful effects of radiation exposure from uranium and plutonium. What it does suggest, however, is that the resilience of the human body to some of the most harmful chemicals and toxicants known is absolutely stunning.

You can find the original paper here.

Posted in From the vault: Past research from our people

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