Answer to Question #3819 Submitted to "Ask the Experts"

I was involved in a decomissioning at a Department of Energy facility. The facility dealt with many types of uranium compounds in powder form, including uranium tetrafluoride. I had a possible intake of one breath of 4.5% ²³⁵U enriched uranium tetrafluoride. This was virtually 100% uranium tetraflouride. During a quality-assurance inspection of an amount of uranium tetraflouride that was sealed in a plastic bag inside a drum, an unidentified object was found in the bag. As I was attempting to identify the material by feel, another worker ripped a portion of the plastic bag open. Almost immediately I smelled or tasted a musty/earthy taste or odor and backed away. I did not see any airborne particles. I was wearing a full-face respirator with high efficiency particulate air filteration. As I completed my work, I frisked (with a beta/gamma frisker) all around my face mask, especially the neck area, and found no contamination. After I took my mask off, I frisked all around my mouth and nose very carefully and found no contamination. I described the smell/taste to another worker and he indicated that smell is common when dealing with uranium tetraflouride, even when the material is not airborne. I concluded that it was most likely an odor of some sort as records indicated the material was placed into the bag seven years prior to our inspection. For reasons I do not really understand, I did not report the possible inhalation for four days to our safety people. They immediately sent me for urinalysis. The urinalysis returned below detectable limits for uranium. Although I did not feel confident that the urinalysis was worthwhile, the person who told me the sample was negative assured me that if I had received a measurable dose in the first place, it would have still been detectable. I believe the test analyzed total uranium. Very little information is printed on health effects of enriched uranium inhalation. A person working with me doing the same work was recently diagnosed with pancreatic cancer. We are both in our 40s and our contact with uranium compounds began approximately two years ago and ended approximately one year ago. Could a pancreatic tumor have been caused by uranium compounds produced in this period of time? The other worker did not have a known or suspected inhalation of uranium compounds. I do not have any specific additional health problems at this time. Is it likely that the "breath" I received, even if it was indeed airborne 4.5% enriched uranium tetraflouride, could be a substantial health risk to me, given the normal uranium that would be ingested/inhaled over a lifetime? I am aware that a "breath" of a material that I could not see is very subjective and not measurable, but I am seeking some advice on how much this situation may affect me. It is unclear whether it is likely to not effect me at all, or whether it is likely to effect me considerably if I inhaled ANY amount of the material. I am quite informed as to the opinions and advice related to depleted uranium, but the safety personnel, radiological personnel, and supervisors basically would not talk to me at all about my situation. So I hope you can find the time to answer my questions to the best of your ability.

You apparently had a very interesting encounter with some uranium tetrafluoride and I can certainly understand why you might be concerned about this potential exposure. And, as a professional health physicist, I am very concerned that you apparently have been unable to get the answers you seek from the safety and radiological personnel at your workplace and hope that my response will be helpful to you and address your concerns.

Although you have provided a very detailed description of the events, there is likely additional information available that might affect your specific situation. Therefore, please consider the response that follows to be of a provisional nature as it is based only on the limited information you have provided. Even though it was taken several days after you suspect that you were exposed, the urinalysis provides very important information as to what your exposure might have been. Based on the negative results, it would seem reasonable to conclude that your uptake of uranium, if any, was minimal. The fact that you found no contamination around your nose supports this conclusion. Additional information could be obtained from air sampling results in the workplace. Were air samplers in operation at the time you could have been exposed? If so, these could provide very important additional information regarding the potential for intake of uranium.

You indicated that your potential exposure was acute—that is a "breath." Given the low enrichment of the uranium (4.5%), the chemical hazards would likely be of greater significance than the radiological hazards. Thus, if you had in fact taken up a significant quantity of uranium—which from the negative urinalysis it appears you did not—based on reports of acute intakes of uranium that have appeared in the scientific literature (see below), minor, transitory kidney effects might have been seen by examination of urine.

You noted that you had begun work with uranium about two years ago, and ceased contact with uranium about a year ago. Typically, radiogenic cancers are not expressed (that is, they do not appear) until many years—typically decades—after the exposure. As the exposure of you and your coworker occurred less than two years ago, it is extremely unlikely that any radiogenic cancer would have appeared so soon.

There is a very large body of scientific literature on uranium, including a fairly recent book, Review of Radiation Risks and Uranium Toxicity, written by Dr. Allen Brodsky and published by RSA Press. You may also wish to look at some reports of acute accidental inhalation exposures to uranium. Two suggested publications are "Evaluation of Health Effects in Sequoyah Fuels Corporation Workers from Accidental Exposure to Uranium Hexafluoride" by D.R. Fisher, M.J. Swint, and R.L. Kathren which was published in 1990 as Report NUREG/CR-5566 (PNL-7328) by Battelle Pacific Northwest National Laboratory and the article "Acute Accidental Inhalation of U: A 38-year Followup" by R.L. Kathren and R.E. Moore, published in the journal Health Physics Volume 51, pages 609-619, 1986. You could likely find these references in a medical school library.

I hope that I have answered your questions.

Ronald L. Kathren, CHP