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The Good, Bad, and Ugly Truth about Radiation

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Ben Edwards, Assistant Director of Radiation Safety at Vanderbilt Environmental Health and Safety speaks with Teera Wilkins about radiation exposure parameters.


Teera Wilkins:          Welcome to this edition of the Vanderbilt University Health and Wellness Wellcast.  I am Teera Wilkins with Occupational Health Clinic.

Today, I am interviewing radiation safety assistant director, Ben Edwards.  We all are exposed to some type of radiation like sunlight, radio waves, and microwaves.  Well today, Mr. Edwards will provide us with a clear understanding of radiation and what is considered harmful.  Good morning Mr. Edwards and thank you for talking to us.

Ben Edwards:          Good morning Teera.  Thanks for coming.

Teera Wilkins:          Let’s start with in general terms what is radiation?

Ben Edwards:          Well technically, radiation is just energy moving through space, but most people use the term to mean ionizing radiation.

Teera Wilkins:          Can you describe the different levels of radiation exposure?

Ben Edwards:          Well, we are awash in a sea of both ionizing and non-ionizing radiation, but from now on, I will focus just on ionizing radiation, so that is what most people are interested in.  The basic unit of ionizing radiation dose in this country is the rem, and we get about a third of a rem every year just from living in Nashville.  In addition to that natural background radiation, we also get radiation from many other sources including consumer products, air travel, and medical procedures.  About half of the radiation dose to the average person in the U.S. is from natural background.  Most of the others half is from medical procedures, and the tiny remainder is from all other sources.

Teera Wilkins:          As we know, there are some employees who obviously work around radiation.  How does Vanderbilt Environmental Health and Safety know how much radiation an employee is exposed to?

Ben Edwards:          Workers can be exposed to radiation from both radioactive material and from devices like x-ray machines.  So, there are a lot of radiation sources to consider.  Fortunately, we have several things going for us.  First of all, radiation sources are heavily regulated.  So, we have always had a good handle on where they are.  Second, Vanderbilt and many similar institutions across the country have been providing workers with radiation dosimetry monitoring badges for over a half a century creating a vast amount of historical dose data both here and elsewhere.  It gives us a very good idea of which types of jobs may entail a measurable radiation dose and which ones will not.  For example, Vanderbilt is currently monitoring the radiation dose of well over 2000 employees with dosimetry badges.  We find that typically less than about 5% of our monitored radiation workers get any significant radiation dose.  Individual workers can look at their own dosimetry badges also at any time by following instructions on the VEHS website.

Teera Wilkins:          What steps do we have in place to protect employees from being exposed to too much radiation?

Ben Edwards:          To prevent any of our employees from getting significant doses, we have a very well-established radiation safety program at Vanderbilt.  First and foremost, all radiation workers are required to complete appropriate radiation safety training before they work with radiation.  This training ensures that they know how to recognize radiation sources, keep the doses as low as reasonably achieving while they work with those sources, and otherwise comply with all of the regulations and policies to protect their coworkers, the public, and the environment.  The only significant source of radiation exposure for most of our radiation workers is diagnostic x-ray machines.  Regulation generally requires that everyone in the room besides patient during an x-ray procedure must wear shielding personal protective equipment like a lead apron that does a terrific job of reducing the dose to almost nothing.

Teera Wilkins:          What about women who become pregnant?  What steps can they take to protect themselves while pregnant?

Ben Edwards:          Epidemiological study suggests that the incidence of developmental abnormalities begins to increase in populations exposed in utero to around 10 rem.  So, again the 5 rem annual occupational dose limit seems to provide a good margin of safety below any known effects, and of course, almost all of our radiation workers have far lower doses.  If a radiation worker becomes pregnant, they have the option of voluntarily declairing their pregnancy to the Occupational Health Clinic using a declaration form they can find on the OHC and VEHS websites.  The declaration is completely confidential.  Declared pregnant workers have a dose limit of half a rem to the fetus during the entire pregnancy, and radiation safety will review the workers’ dose history and work environment to see if any changes or restrictions are appropriate.  We have about 30 declared pregnant radiation workers at any time.

Teera Wilkins:          Well, thank you for allowing me the opportunity to share a better understanding of radiation.

Ben Edwards:          Thank you Teera.

Teera Wilkins:          Thanks for listening.  Please feel free to leave us any comments on this Wellcast on the form at the bottom of this page.  If you have any story suggestions, please email us at or you can use the “Contact Us” page on our website at

— end of recording (05:26) —

Posted on Friday, July 19, 2013 in Occupational Health Clinic, Wellcasts and tagged , ,


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