What you need to know about radiation exposure

The Centers for Disease Control and Prevention reported that people around the world are exposed to small amounts of radiation every day from a variety of sources. In fact, natural sunshine, foods, microwave ovens, and nuclear power plants are all on the list of exposure sources. This abundance of radiation sources begs the question of whether there is a level of radiation exposure that is considered safe. The Environmental Protection Agency reports that there really is no firm basis for setting safe exposure levels. Studies have shown that over time, radiation exposure of any source can lead toward risks of various cancers, especially thyroid carcinomas. 

Radiation is measured in rems, a word that means a large unit of radiation. An mrem is a milli-unit of radiation, which is the scientific measurement for radiation emissions and exposures.

Here is a list of annual radiation exposures from the following sources:

• Cosmic/Atmospheric Radiation: 25 mrem (at sea level…higher mrem at higher levels)
• Soil/Earth: 50 mrem
• Radon: 200 mrem
• Food (carbon-14 and potassium): 20 mrem
• Other People (who naturally contain carbon-14 and potassium): 40 mrem
• Watching TV: 1 mrem
• Wearing False Teeth: 0.1 mrem
• Living Near a Nuclear Power Plant (functioning properly): 0.01 mrem
• Wearing a pacemaker: 75 mrem
• Living with someone wearing a pacemaker: 7.5 mrem

Receiving Medical X-Rays:

• Extremity (arm, leg, etc) Xray: 1 mrem
• Dental Xray: 1 mrem
• Chest Xray: 6 mrem
• Nuclear Medicine (thyroid scan): 14 mrem
• Neck/Skull Xray: 20 mrem
• Pelvis/Huip Xray: 65 mrem
• CAT Scan: 110 mrem
• Upper GI Xray: 245 mrem
• Barium Enema: 405 mrem

The average annual dose rate for Americans is 360 mrems per year. The American Nuclear Society states that the risks of dying from radiation-causing cancers increase if the body accumulates 250,000 mrem in one lifetime. According to the Society, that would mean an annual exposure of 3,000 mrem per year over the course of 80 consecutive years – a highly improbable occurrence.

Unusual radiation exposures:

• Airplane ride (39,000 feet): 0.5 mrem per hour
• Coast-to-Coast Airline Flight: 5 mrem
• Drinking Water: 5 mrem
• Natural gas in the home: 9 mrem
• Three Mile Island Exposure at Meltdown: 80 mrem
• Radiation from Cancer Treatments: 100,000 mrem
• Japan’s Nuclear Power Plant Meltdown Potential: 100,000 to 1,000,000 mrem

Exposures and their associated symptoms, as listed by the Environmental Protection Agency:

Exposure in rem	Health Effect	Time for onset after immediate exposure
5-10	Changes in blood chemistry	Hours
50	Nausea	Hours
55	Fatigue	Hours
70	Vomiting	Hours
75	Hair loss	2-3 Weeks
90	Diarrhea	2-3 Weeks
100	Hemorrhage	2-3 weeks
400	Possible death	Within 2 months
1,000	Destruction of intestinal lining Internal bleeding Death	1-2 weeks
2,000	Damage to central nervous system Loss of consciousness Death	Minutes, Hours or Days (depending on the health of the individual before exposure)

References:

Centers for Disease Control and Prevention. (2011). Frequently asked questions about a radiation emergency. Retrieved March 14, 2011 from http://www.bt.cdc.gov/radiation/emergencyfaq.asp.

Environmental Protection Agency. (2010). Radiation protection: Health effects. Retrieved March 14, 2011 from http://www.epa.gov/rpdweb00/understand/health_effects.html.

Idaho State University. (2011). Radiation and risk. Retrieved March 14, 2011 from http://www.physics.isu.edu/radinf/risk.htm.

Nuclear Detection Products. (2011). What radiation levels are considered safe? Retrieved March 14, 2011 from http://www.blackcatsystems.com/GM/safe_radiation.html.

Torres, M. (2011). Japanese nuclear meltdown means detrimental health effects worldwide. Retrieved March 14, 2011 from http://www.infowars.com/japanese-nuclear-meltdown-means-detrimental-health-effects-worldwide/.