Radioactive Chair
Have you ever wondered how safe dental x-rays are? Then you are not alone. Let’s explore the facts and hopefully make some conclusions about the safety of dental x-rays. Radiation is a natural phenomenon. We get it from food, air, cosmic radiation from space, and from the ground (typically from radon gas that seeps from the earth).
The EPA estimates that a person living in the United States receives about 3,000 microsieverts of radiation each year from these background sources. Health physicists generally agree on limiting a person’s exposure beyond background radiation (3,000) to about 1,000 additional microsieverts per year from all non-natural sources. Some scientists even assert that low levels of radiation are beneficial to health (this idea is known as hormesis).
Let’s explore some every day sources of radiation. Bananas contain about 1 microsievert of radiation. A five-hour airline flight exposes us to 25 microsieverts. A year of TV watching will add 10 microsieverts and breathing air for one day yields 6 microsieverts.
A chest x-ray yields 120 microsieverts while a mammogram yields 440 microsieverts. A single abdominal CT scan yields about 7,000 microsieverts.
So how do dental x-rays compare?
A single intraoral image transmits about 4 microsieverts of radiation. Kids typically receive two bitewings for a dose of 8 microsieverts (A bitewing is a type of x-ray image which is taken by a dentist to assess oral health or to look at a particular area of the mouth – Ed.). Adults typically receive four bitewing radiographs for a dose of 16 microsieverts. A panorex can yield 26 microsieverts and a full mouth series can yield 88 microsieverts.
The United States Nuclear Regulatory Commission and the EPA state that the annual occupation limit for an adult is around 50,000 microsieverts. Consequently, a patient would need to receive 3,125 sets of 4 bitewing x-rays in a single year before hitting that limit. If an individual received yearly bitewings as an adult from age 20 to age 100, that would only result in 1,280 microsieverts of exposure.
Is any amount of radiation safe? According to the EPA, there is no firm basis for setting a “safe” level; however, there do appear to be threshold exposures. For example, the smallest acute health change listed by the EPA, changes to our blood chemistry, would result from an exposure of 500,000 microsieverts. That would equate to 166 years of living with regular background radiation of 3,000 microsieverts per year or eating 136.9 bananas every day for 100 years.
So, do you need to wear a special aluminum foil hat when you have dental x-rays taken? The answer is no. In fact, because the radiation exposure is so low, lead aprons are not physiologically necessary; however, their use is still recommended by various organizations for dental patients, especially for children and pregnant women whose tissues are more radiosensitive.
In conclusion, the health benefits of dental x-rays outweigh the apparent risks.
References:
1. Clinicians Report October 2012, Volume 5, Issue 10, page 2.
2. http://www.epa.gov/radiation/rert/radfacts.html
3. Ionizing radiation exposure of the population of the United States. Bethesda, Md.: National Council on Radiation Protection and Measurements. 2009. ISBN 978-0-929600-98-7. NCRP No. 160.
Dr. Laudie practices dentistry in Emporia. Shape Up, Emporia!, is a weekly fitness and health column aimed at readers of all ages to get off the couch and get into shape. Each week will feature a fitness, health or nutrition professional from around the area who will share some friendly tips on how to improve your overall health. Our goal is to make getting in shape fun and easy to fit into your existing lifestyle and daily routine.