Answer to Question #911 Submitted to "Ask the Experts"

Q

I am 26 weeks pregnant. I work in clinical research. My coworker is involved in an experiment where he uses xenon gas to flood a room. He did this on a Monday. By Wednesday, I was in that room for about an hour preparing for a next-day procedure. Thursday I was in that room again for about an hour and a half when a colleague pulled me out of the procedure saying that I should not be in that room because the clearing time for the xenon takes about five days. Prior to this incident about two months ago, they told me that I should not worry about going in the room the day after they use it for experiments because xenon dissipates in 20 minutes. They also reassured me after this recent exposure not to worry because they only use a small amount of radiation and that I am far out in my pregnancy to have the radiation effect the fetus. No matter what they say, I can't help but worry. First of all, nobody warned me that I should stay away from that room for five days. Secondly, there was no sign left on the door to warn me of the presence of radiation in that room. My questions are: Can you tell me something about xenon? What are the possible effects of xenon to a 26-week-old fetus? Is there a carcinogenic risk to the baby sometime in the future? What about mental retardation, is there a danger of that? Can you please tell me how long should I stay clear of the room once they flood it with xenon gas? In terms of employee safety, shouldn't there be a regulation or a protocol to follow to keep the safety of employees, especially pregnant employees, to prevent radiation exposure? Where and how can I refer to that policy? I am sorry for the long question but since I think that I had direct exposure to the radiation because I was in that room for a long period of time, I just need some answers to ease my mind. Your response is greatly appreciated.

A

The most important thing for you to know is that the radiation that you and your baby are exposed to will more than likely not cause any harm. I have calculated fetal radiation exposures for many women receiving x rays, CT scans, or fluoroscopy after car accidents and, in each case, the radiation exposure was very much higher than what you can expect to be exposed to. In each case, the medical advice was to let the pregnancy proceed normally, and there were no problems at all. So your biggest concern, about your baby, is not really an issue. There is a chance that any pregnancy will not end happily, but the chances are excellent that this radiation exposure will NOT cause problems.



I think that what you really need to do is to call the radiation safety officer (RSO) for your organization—the RSO will be able to tell you more of the particulars about the use of xenon in this lab and the policies regarding its use. There are two issues, I think, that are important to know. First, the radioactive half-life of ¹³³Xe is about five days. This is the amount of time it takes the xenon to decay by emitting radiation. However, the xenon is a gas, so it won't stay put in the room to decay. State and federal regulations require ventilation in rooms where xenon is used, so it will not be present in the room for more than a few minutes after it's released. In fact, in rooms at my university where people are going to be using xenon, I have to make sure that it will clear out of the room relatively quickly. So, no matter what the half-life is, it will all be out of the room in 20-30 minutes. That means that you can go into the room after 20 minutes or so or, if you're in the room, after 20-30 minutes, your exposure will stop. Again, I would urge you to call your RSO to find out the specifics in this particular room.



Andy Karam, CHP

University of Rochester