Questions Everyone Asks
Since 2002, you have been asking the Health Physics Society's Ask the Experts editors for answers to your questions about radiation, giving us the rare opportunity to know what is on your mind, your worries and concerns about radiation, and what others have told you about radiation. We are very grateful to you for sharing some of your time with us and appreciate your confidence in our ability to answer your questions.
Your most common questions and our answers are the topic of this section. Personal information has been edited out of questions, and sometimes questions with a subject or idea that appears to be on your mind and the minds of many others have been combined into one.
Pregnancy
I am pregnant and am wondering…
…What are the risks to my unborn child from dental, mammogram, chest, extremity, head, or CT exams that involve x rays, but don't directly expose my abdomen?
There will be minimal, if any, harm to your unborn child from radiation exposure when x rays are taken of areas other than the abdomen because the x-ray beam is focused only on the area of interest to minimize radiation doses to other areas of the body.
…Is it necessary to put a lead apron over my abdomen for x-ray exams?
Some state regulations will require the lead apron when it will not interfere with the exam being done. In reality, with current x-ray exams, it is not likely the unborn child would be exposed unless the abdomen is directly exposed—lead apron or not. If you had an x-ray exam of an area outside the abdomen and forgot to ask for a lead apron, its okay, the unborn child received little, if any, radiation exposure.
…Is it okay to stand next to one of those airport baggage-screening machines?
Yes. The x-ray machines at the airport are shielded. There is no radiation exposure of the unborn child when standing next to the baggage-screening machines.
…Is it risky to fly?
No, not because of radiation exposure. Any additional radiation exposure from flying is too small to increase pregnancy risks.
…Can I stand close to a microwave oven while it is operating?
Yes. Current models of microwave ovens for general use are shielded to reduce leakage to very low or even zero levels. A microwave emits electromagnetic radiation of a frequency that is different from the radiation of x rays and such. From a general safety standpoint, though, you should stay around in case your food gets superheated and the packaging begins to burn.
…Can I continue to use my cell phone?
Yes. A cell phone emits electromagnetic (EM) radiation of moderate frequency, which is much different than the radiation of x rays. This type of exposure does not increase risk of harmful effects to the unborn child.
…Is it okay to have an MRI exam for back pain?
Yes. There is no evidence that a standard diagnostic MRI (magnetic resonance image) performed on a woman who is pregnant will cause harmful effects. The Food and Drug Administration (FDA) and other regulatory agencies have strict limits on MRI field strengths at diagnostic levels.
…Are there any risks to babies from radiation emitted from computers?
No. Today, it would be difficult to find a computer (the monitor actually) that exposes the user to large or even moderate amounts of electric or magnetic field radiation. There is no reason to be worried about radiation exposure while using a computer when you are pregnant.
Tanning
Does a tanning bed cause skin cancer and, if so, how long does it take?
Yes. Ultraviolet (UV) light has been associated with an increased chance of skin cancer in studies of individuals who have skin cancer. Major scientific and medical organizations have agreed that UV light causes an increased risk of skin cancer and recommend that you limit your exposure to UV—from natural sunlight as well as from tanning booths. The relationship between UV exposure and cancer risk is not clear except that we know that more exposure increases your risk of cancer. So it is not possible to say how long a tanning bed has to be used before causing skin cancer for a specific individual.
Which type of tanning causes more damage to the skin and is most harmful—tanning beds or sun tanning?
The type and amount of UV radiation emitted from some tanning beds appear to be similar to that of noontime summer sun. The reaction of a person to UV light from tanning beds or the sun is thought to be similar regardless of the source of the exposure.
Can tanning beds affect ovaries (eggs) or testes (sperm), my unborn child if I am pregnant, or my milk if I am breast-feeding?
No. UV radiation does not travel very far into the body. Therefore, it won’t affect ovaries, sperm, your unborn child if you are pregnant, or your milk if you are breast-feeding.
If I use sunblock for protection, am I safe from skin cancer?
No. Sunblock will help reduce exposure to UV rays, but is not totally effective in preventing skin cancer. This is mainly because it wears off and needs to be reapplied. If sunscreen is not applied often enough and thickly enough, it may give a false sense of security leading to even more time in the sun. The lesson? Apply sunblock often whenever you are in the sun and especially after activities that may have washed the sunblock off (swimming, activities causing you to sweat).
How long should I wait to try to become pregnant after x-ray exams that have exposed my ovaries or my husband's testes? Can I become sterile after having x rays?
There is no evidence that there are any effects on the ovaries or sperm at doses used in diagnostic x-ray procedures and radiation doses from routine medical x rays are too small to cause sterility or effects on a future pregnancy.
Nuclear Power
During normal operations, do commercial nuclear power plants release radioactive material and, if so, is the public told about these releases?
Yes. Nuclear power plants routinely produce radioactive gasses and liquid wastes during normal operations. A plant has tanks designed to store gas and liquid radioactive materials that are generated during normal operation. The radioactive material is held for a period of time to allow for the radioactivity level to decrease before being treated and/or released in a planned, monitored way. This keeps the amount of radioactive material in releases low, well within regulatory limits (which are set at less than one-tenth of the amount of natural background exposure we receive each year).
Prior to the release of the radioactive material, it is sampled and analyzed and calculations are performed to ensure that releases are below regulatory limits. Once the calculations verify the radioactivity is below regulatory limits, the radioactive material is released in a controlled, monitored process. Advance notifications to the public are not required and are not routinely done when releases are made in accordance with the plant’s procedures and are below regulatory limits. The plants do maintain records of all releases and this information is publicly available through the Nuclear Regulatory Commission (NRC, www.nrc.gov). Routine sampling of water from nearby lakes, ponds, etc., performed by the plant operators and independently by states also provides advance warning of (or an alert to) any potential radioactive liquid releases.
Releases that are unexpected, are not made in accordance with procedures, or are above regulatory limits are required to be reported to the Nuclear Regulatory Commission and to the state when they are discovered. These reports are made available to the public.
How is radiation and radioactive material that can expose a member of the public measured around nuclear plants? What do the results tell us?
During normal operations, penetrating radiation (like gamma rays or x rays) emitted from the radioactive materials in the reactor or in the systems and buildings of the plant are not able to expose someone outside the boundary of the plant. Nevertheless, radiation monitors are placed on the fence line surrounding the site to directly measure any radiation exposure that might occur.
Radioactive materials that could cause radiation exposure near nuclear power plants are generally monitored by sampling air, food, and water supplies for radioactivity content. Possible radiation doses are estimated by looking at how humans might be exposed to that radiation. Radioactive emissions may be released to both air and water. The radioactive material in the air could be breathed in directly or could settle or deposit on local vegetation. Therefore, samples are taken of the air emissions themselves and of food products such as garden vegetables. Some radioactive material could also land on pasture grasses that cows eat, so milk and vegetation are sampled. Nuclear power plants near bodies of water are required to check for radioactive material in all nearby lakes, ponds, and streams, so water samples are taken from the liquid waste stream from the plant. Other water samples are taken from the nearest public water supplies. Samples of fish are caught and analyzed as well. The amount of radioactive material allowed to be released from power plants is strictly controlled by the utility and regulated by the Nuclear Regulatory Commission.
What went on at Three Mile Island and Chernobyl? Were they different?
Yes, they were very different. In the 65 years since the start of the operation of the first nuclear reactor there have been several accidents that have affected people. Two of the widely publicized events were Three Mile Island in the United States in 1979 and Chernobyl in the Ukraine in 1986. Click on the links to read about each incident.
What is a dirty bomb and what can happen?
A dirty bomb is a regular bomb (plastic explosive, for instance) made “dirty” because some radioactive material is mixed with the bomb so that when it explodes, the radioactive material is spread around. A dirty bomb is neither a nuclear weapon nor a nuclear bomb. Any injuries or deaths would result from the explosion rather than from exposure to the radioactive material or radiation. Radioactive material from a dirty bomb would likely be deposited within a few blocks or less from the site of the explosion, but could cause public fear and panic—exactly what terrorists are trying to accomplish.
Whether there would be any radioactive contamination, how far it was spread, and whether it could harm anyone depends on the type and amount of radioactive material, the type and amount of explosive, weather conditions, how the individual was exposed to the radiation (external, internal, or both), and how long the individual was exposed to radiation before it was discovered.
And Finally…
The answers to many more questions can be found on the Ask the Experts section of the Health Physics Society web site, along with a place to submit a question if you cannot find the information you want elsewhere.