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Answer to Question #1579 Submitted to "Ask the Experts"Category: Radiation Effects — Biological Effects of Radiation The following question was answered by an expert in the appropriate field: Q
In November 2001, I was on a crew which was performing some cleanup at a nuclear generator facility. I was in a contaminated area for 40 minutes. After the 40-minute exposure, I was told that the contamination level on me was measured at 12 millirem. I was also told that that level of contamination would be expected over a 50-year period of time. I am 28 years old. When our crew finished the job and left the power plant facility, about 3 weeks after the exposure, I was told that no contamination was measured on me. Will I have any long-term concerns for my health from this exposure?
A
It is not fully clear from your description just what kind of exposure you may have received during that 40 minutes of cleanup work at the nuclear generating facility. However, with radioactive contamination that may be taken into the body, the practice is to assign what is called a 50-year committed dose equivalent of CEDE. This is likely what was meant by the 12 mrem dose reported to you. The CEDE is simply the dose that would result from taking the material into the body summed up over a period of 50 years. This does not mean that you will be getting a dose from the material for a period of 50 years. Indeed, quite the opposite is likely true, for most radioactive contaminants found around a nuclear power station are quickly removed from the body by both natural biological excretion as well as radioactive decay. Thus, most of the 50-year dose from an intake of radioactivity will be received relatively soon after the intake, certainly within a few months after the intake. Since you tested negative for radioactive contamination three weeks later, this is likely the case with you. The radiation safety regulations require that for any intake of radioactivity, the CEDE be calculated and assigned to the person as within a one-year period. And, for most radioactive species, this is actually what occurs. However, there are a few long-lived materials that tend to remain in the body for many years, and people who take these into their bodies will continue to receive a dose that grows smaller each year over a period of years. For safety reasons, the dose received over a period of 50 years is calculated and summed, and assigned to the person in the year of the intake. Since you tested negative for contamination only three weeks after intake, it is unlikely that you were exposed to any of these long-lived materials. And a dose of 12 mrem is a small one, roughly equal to (actually somewhat bigger than) the dose from a single chest x ray. So, not to worry, and enjoy those next 50 years. Ron Kathren, CHP Professor Emeritus Washington State University
Answer posted on 25 January 2002. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.
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