What is radiation?

Radiation is energy. It travels in the form of energy waves or high-speed particles. Radiation can occur naturally or be man-made. There are two types:

• Non-ionizing radiation, which includes radio waves, cell phones, microwaves, infrared radiation and visible light
• Ionizing radiation, which includes ultraviolet radiation, radon, x-rays, and gamma rays

What are the sources of radiation exposure?

Background radiation is all around us all the time. Most of it forms naturally from minerals. These radioactive minerals are in the ground, soil, water, and even our bodies. Background radiation can also come from outer space and the sun. Other sources are man-made, such as x-rays, radiation therapy to treat cancer, and electrical power lines.

What are the health effects of radiation exposure?

Radiation has been around us throughout our evolution. So our bodies are designed to deal with the low levels we're exposed to every day. But too much radiation can damage tissues by changing cell structure and damaging DNA. This can cause serious health problems, including cancer.

The amount of damage that exposure to radiation can cause depends on several factors, including

• The type of radiation
• The dose (amount) of radiation
• How you were exposed, such as through skin contact, swallowing or breathing it in, or having rays pass through your body
• Where the radiation concentrates in the body and how long it stays there
• How sensitive your body is to radiation. A fetus is most vulnerable to the effects of radiation. Infants, children, older adults, pregnant women, and people with compromised immune systems are more vulnerable to health effects than healthy adults.

Being exposed to a lot of radiation over a short period of time, such as from a radiation emergency, can cause skin burns. It may also lead to acute radiation syndrome (ARS, or "radiation sickness"). The symptoms of ARS include headache and diarrhea. They usually start within hours. Those symptoms will go away and the person will seem healthy for a little while. But then they will get sick again. How soon they get sick again, which symptoms they have, and how sick they get depends on the amount of radiation they received. In some cases, ARS causes death in the following days or weeks.

Exposure to low levels of radiation in the environment does not cause immediate health effects. But it can slightly increase your overall risk of cancer.

What are the treatments for acute radiation sickness?

Before they start treatment, health care professionals need to figure out how much radiation your body absorbed. They will ask about your symptoms, do blood tests, and may use a device that measures radiation. They also try get more information about the exposure, such as what type of radiation it was, how far away you were from the source of the radiation, and how long you were exposed.

Treatment focuses on reducing and treating infections, preventing dehydration, and treating injuries and burns. Some people may need treatments that help the bone marrow recover its function. If you were exposed to certain types of radiation, your provider may give you a treatment that limits or removes the contamination that is inside your body. You may also get treatments for your symptoms.

How can radiation exposure be prevented?

There are steps you can take to prevent or reduce radiation exposure:

• If your health care provider recommends a test that uses radiation, ask about its risks and benefits. In some cases, you may be able to have a different test that does not use radiation. But if you do need a test that uses radiation, do some research into the local imaging facilities. Find one that monitors and uses techniques to reduce the doses they are giving patients.
• Reduce electromagnetic radiation exposure from your cell phone. At this time, scientific evidence has not found a link between cell phone use and health problems in humans. More research is needed to be sure. But if you still have concerns, you can reduce how much time you spend on your phone. You can also use speaker mode or a headset to place more distance between your head and the cell phone.
• If you live in a house, test the radon levels, and if you need to, get a radon reduction system.
• During a radiation emergency, get inside a building to take shelter. Stay inside, with all of the windows and doors shut. Stay tuned to and follow the advice of emergency responders and officials.

These days, travel by air has become increasingly common, both for business and leisure travel. We are exposed to low levels of radiation when we fly. You would be exposed to about 0.035 mSv (3.5 mrem) of cosmic radiation if you were to fly within the United States from the east coast to the west coast. This amount of radiation is less than the amount of radiation we receive from one chest x-ray.

How am I exposed to radiation from air travel?

Radiation from air travel comes from cosmic radiation, or radiation from space. Cosmic radiation is produced by the stars, including our own sun.

How much radiation can I get from air travel?

The amount (dose) of radiation you get from air travel is low, but the dose depends on a few factors.

These levels of radiation are small and unlikely to affect human health.

1. Duration of the flight

The longer you are on a flight, the more radiation you receive.

2. Altitude

The higher you are in altitude, the higher the dose of radiation. This is a result of less shielding of cosmic radiation by the atmosphere at higher altitudes.

3. Latitude

The farther north or south you are from the Equator, the more radiation you will receive. This is a result of the Earth’s magnetic field deflecting some of the cosmic radiation away from the equator and toward the North and South poles.

Whether you fly or not, a person’s average dose from cosmic radiation is 0.33 mSv (33 mrem) or 11% of our yearly exposure to all natural sources of radiation.

Average Annual Dose for Natural Sources of Radiation

Reference: National Council on Radiation Protection and Measurements. NCRP Report No. 160, Ionizing Radiation Exposure of the Population of the United States.

What is the risk from radiation from air travel?

Air travel exposes travelers to low levels of radiation.

Radiation from air travel is a result of naturally-occurring radiation from space we are exposed to every day.

When flying in the United States or elsewhere, we are subject to airport security screening. Airport security screening in the United States includes the use of body-scanning units that release low levels of radiation.

How am I exposed to radiation from airport security screening?

Body scanners using millimeter wave technology are being used in United States airports. Image credit: Transportation Security Administration

The Transportation Security Administration (TSA) is using body-scanning units at a number of U.S. airports. These body-scanning units traditionally use millimeter-wave technology.

Millimeter-wave technology uses non-ionizing radiation in the form of low-level radio waves to scan a person’s body. A millimeter-wave body scanner uses two antennas that rotate around a person’s body to construct a 3-D image that resembles a fuzzy photo negative. The image is sent to a remote monitor. Millimeter-wave technology does not use x-rays and does not add to a person’s ionizing radiation dose.

You may have heard that some airports previously used “backscatter” technology, which involved x-rays. Backscatter technology is no longer being used in U.S. airport security screenings.

What is the radiation risk from airport security scans?

As mentioned above, the United States uses millimeter-wave technology in airport security scans. This form of technology uses low-energy non-ionizing radiation that releases thousands of times less energy than a cell phone.

We are all exposed daily to small amounts of radiation from natural sources of radioactive material. Much of this natural radiation comes from radioactive materials in building materials and in soil in the environment.

What building materials contain radioactive material?

Some building materials contain low levels of radioactive material.Building materials that are made up of sandstone, concrete, brick, natural stone, gypsum, or granite are most likely to emit low levels of radiation.

Radioactive materials in sandstone, concrete, brick, natural stone, gypsum, and granite contain naturally-occurring radioactive elements like radium, uranium, and thorium.These naturally-occurring elements can break down or decay into the radioactive gas radon. Depending on the amount of these materials present, they may also cause small increases in radiation levels. Amounts (doses) of radiation in building materials depend on the type and amounts of materials used.

How much radiation exposure can I get from building materials?

Building materials that are made up of sandstone, concrete, brick, natural stone, gypsum, and granite are highly unlikely to contain radioactive material that will increase radiation dose above the low levels of background radiation we receive on a daily basis.

Radioactive material in building materials may add to indoor radon levels. However, radon is more likely to get into your home through cracks and holes in your foundation (underneath the home) or private well water (groundwater). Elevated indoor radon levels may pose a risk to human health.

You can test your building to make sure there are safe levels of radon.

What is the risk from radiation found in building materials?

For the most part, the levels of radioactive materials found in building materials are very low. These low levels of radioactive material, and the radiation emitted by them, are unlikely to harm human health.

In certain cases, radioactive radon gas may be released from building materials, and you may need to take steps to protect yourself. If you are concerned about the levels of radon in your home, get it tested.

Most of us depend on cell phones every day. Some people wonder if cell phones can cause health problems. Here’s what you should know about cell phones and your health.

Can using a cell phone cause cancer?

There is no scientific evidence that provides a definite answer to that question. Some organizations recommend caution in cell phone use. More research is needed before we know if using cell phones causes health effects.

Do cell phones give off (emit) radiation?

Yes – cell phones and cordless phones use radiofrequency radiation (RF) to send signals. RF is different from other types of radiation (like x-rays) that we know can be harmful. We don’t know for sure if RF radiation from cell phones can cause health problems years later. The International Agency for Research on Cancer (IARC) has classified RF radiation as a “possible human carcinogen.” (A carcinogen is an agent that causes cancer.)

Should people stop using cell phones?

At this time we do not have the science to link health problems to cell phone use. Scientific studies are underway to determine whether cell phone use may cause health effects. It is also important to consider the benefits of cell phones. Their use can be valuable in an urgent or emergency situation – and even save lives.

If you are worried about cell phone use, follow the tips below.

Cell phone tips

To reduce radio frequency radiation near your body:

• Get a hands-free headset that connects directly to your phone.
• Use speaker-phone more often.
• In the past, RF interfered with the operation of some pacemakers. If you have a pacemaker and are concerned about how your cell phone use may affect it, contact your health care provider.

What research is being done to learn more about cell phones and health?

Scientists are continuing to study the possible health effects of cell phone use. For example, the World Health Organization (WHO) is currently looking into how cell phones may affect:

• Some types of tumors (a lump or growth)
• Our eyes
• Sleep
• Memory
• Headaches

CDC estimates that cigarettes and tobacco use kill more Americans each year than alcohol, car accidents, suicide, AIDS, homicide, and illegal drugs combined. Most people know that cigarette smoke and tobacco contain many toxic substances including tar, arsenic, nicotine and cyanide.The common dangers of cigarettes have been known for decades. However, few people know that tobacco also contains radioactive materials: polonium-210 and lead-210. Together, the toxic and radioactive substances in cigarettes harm smokers. They also harm people exposed to secondhand smoke. For more information on secondhand smoke, please see the CDC website, Smoking and Tobacco Use.

What are Polonium-210 and Lead-210?

Radioactive materials, like polonium-210 and lead-210 are found naturally in the soil and air. They are also found in the high-phosphate fertilizers that farmers use on their crops. Polonium-210 and lead-210 get into and onto tobacco leaves and remain there even after the tobacco has been processed.

When a smoker lights a cigarette and inhales the tobacco smoke, the toxic and radioactive substances in the smoke enter the lungs where they can cause direct and immediate damage to the cells and tissues. The same toxic and radioactive substances can also damage the lungs of people nearby.

How can Cigarettes, Tobacco, and Radiation Affect Your Health?

Polonium-210 and lead-210 accumulate for decades in the lungs of smokers. Sticky tar in the tobacco builds up in the small air passageways in the lungs (bronchioles) and radioactive substances get trapped. Over time, these substances can lead to lung cancer. CDC studies show that smoking causes 80% of all lung cancer deaths in women and 90% of all lung cancer deaths in men. For more information about the increased health risks of smoking, see CDC’s Health Effects of Cigarette Smoking.

A variety of consumer products contain radioactive materials. In some, the radioactive material is a working part of the product. In others, radiation is present because some component contains naturally-occurring radioactive materials.

Consumer products with radioactive components or emissions:

• Smoke detectors: most smoke detectors available for home use contain americium-241, a radioactive element. Unless tampered with, smoke detectors pose little to no health risk; a smoke detector’s ability to save lives far outweighs the health risks from the radioactive materials.
• Clocks and watches: some luminous watches and clocks contain a small quantity of hydrogen-3 (tritium) or promethium-147. Older watches and clocks (made before 1970) may contain radium-226 paint on dials and numbers to make them visible in the dark. Avoid opening these items because the radium could flake off and be ingested or inhaled. 
• Older camera lenses: some camera lenses from the 1950s-1970s incorporated thorium into the glass, allowing for a high refractive index while maintaining a low dispersion. The health risk from using older camera lenses is low; the radiation received when using a thoriated lens camera is approximately equal to natural background.
• Gas lantern mantles: older, and some imported, gas lantern mantles generate light by heating thorium (primarily thorium-232). Unless gas lantern mantels are used as the primary light source, radiation exposure from thorium lantern mantles is not considered to have significant health impacts.
• Televisions and monitors: Flat-screen televisions and monitors (e.g., LCD, OLED, plasma) do not use cathode ray tubes (CRTs) and therefore do not produce ionizing radiation. Older televisions and computer monitors that contain CRTs may emit x-rays. X-ray emissions from CRT monitors are not recognized as a significant health risk.
• Sun lamps and tanning salons: the ultraviolet rays from sun lamps and tanning salons are as damaging to skin as the ultraviolet rays of the sun. In fact, warning labels are required which begin "DANGER—Ultraviolet radiation".
• Ceramics: ceramic materials such as tiles and pottery may contain elevated levels of naturally-occurring uranium, thorium, and/or potassium. In many cases, the activity is concentrated in the glaze. Unless there is a large quantity of the material, the amount of radioactivity in these products is unlikely to be greater than natural background levels. However, some older dishware (e.g., pre-1972 Fiesta®ware) can have radioactivity exceeding background levels; to minimize health risks, you may not want to use these pieces for eating or drinking.
• Glass: glassware, especially antique glassware with a yellow or greenish color, can contain easily detectable quantities of uranium. Such uranium-containing glass is often referred to as canary or vaseline glass. In part, collectors like uranium glass for the attractive glow that is produced when the glass is exposed to a black light. Even ordinary glass can contain high-enough levels of potassium-40 or thorium-232 to be detectable with a survey instrument. However, the radiation received when using glassware – even canary or vaseline glass – is unlikely to exceed background radiation levels.
• Fertilizer: Commercial fertilizers are designed to provide varying levels of potassium, phosphorous, and nitrogen to support plant growth. Such fertilizers can be measurably radioactive for two reasons: potassium is naturally radioactive, and the phosphorous can be derived from phosphate ore that contains elevated levels of uranium. 
• EXIT signs: Some EXIT signs contain the radioactive gas called tritium, allowing them to glow in the dark without electricity or batteries. The tritium used in EXIT signs gives off low-level beta radiation, causing a light-emitting compound to glow. Tritium EXIT signs do not pose a direct health hazard, as the beta radiation can be stopped by a sheet of paper or clothing. However, tritium EXIT signs must not be disposed of in normal trash. 

Food may contain different types and amounts of naturally-occurring radioactive materials. For example, a small fraction (0.012%) of potassium in foods is radioactive. Additionally, naturally-occurring radioactive materials in the soil can transfer to crops, and fish and shellfish can take up radioactivity from water or sediments. Generally, food in the home contains too little radioactivity to be detected and does not pose a significant health risk.

A variety of materials may be used to make countertops, including artificial materials, quartz, marble, slate and granite. Granite’s durability and decorative appearance make it a popular building material in homes and buildings.

About Granite Countertops and Radiation

Granite, like any other stone, may contain veins of naturally occurring radioactive elements like uranium, thorium, and their radioactive decay products. These trace concentrations may vary from stone to stone, or even within a single slab of granite. 

If present, uranium, thorium or radium will decay into radon, a colorless, odorless, radioactive gas that may cause lung cancer. Radon released from granite building materials can be released over the lifetime of use but typically will be diluted by ventilation.

In addition to radon, naturally occurring radioactive elements in the granite can emit small amounts of beta and gamma radiation. However, any radiation present would decrease quickly with increasing distance from the source. It is extremely unlikely that radiation from granite countertops would increase annual radiation doses above normal, natural background levels. 

Identifying Radiation in Granite Countertops

Identifying the presence and concentration of radioactive elements in each specific granite countertop requires sophisticated instruments. These instruments require proper calibration and a knowledge and trained user to interpret the results. If you are interested in learning about testing methods, information is available from your state’s radiation protection program. 

Radon originating from the soil beneath homes is a more common problem and a far larger public health risk than radon from granite building materials. Radon is the second leading cause of lung cancer and is estimated to cause tens of thousands of lung cancer deaths in the U.S. each year. To reduce the risk of lung cancer from exposure to radon, EPA recommends testing all homes for radon and mitigating high levels, regardless of whether the home contains granite countertops.

Testing the Air in Your Home for Radon

To reduce the risk of lung cancer from exposure to radon, EPA recommends testing all homes for radon, regardless of whether the home contains granite countertops. Call 1-800-SOS-RADON (767-7236) or purchase do-it-yourself home radon test kits at home store retail locations, or online.

Testing is inexpensive and easy—it should only take a few minutes of your time. If elevated levels are measured, the most effective action may be to install a device that removes radon from the air in the home, rather than to remove granite countertops.

Although high doses of ionizing radiation can be harmful to human health, radiation and radioactive materials are used every day in medical settings to improve health outcomes and even save lives.

About Imaging Procedures

Radiation is used in many medical imaging procedures. Medical imaging procedures deliver x-ray beams, a form of ionizing radiation, to a specific part of the body creating a digital image or film that shows the structures inside that area like bones, tissues, and organs. Healthcare providers can use these images for diagnostics, finding out what is causing your health problem, or sometimes to guide treatment. Imaging procedures are usually performed in radiology or imaging centers in hospitals or clinics by a radiologist, a medical professional who is trained and certified to conduct imaging studies with radiation. Medical radiation practices and equipment are regulated by state and federal programs to ensure safety.

Benefits and Risks

There are possible short-term and long-term risks from the very low doses of radiation exposure from imaging procedures. Ionizing radiation can damage cell DNA, but in the low amounts used in each imaging procedure cells can normally repair themselves. When cells get too much radiation over time, this damage can lead to cancer.

Although we all are exposed to ionizing radiation every day, any added exposures, including from imaging procedures, slightly increases the risk of developing cancer later in life.

Usually, the benefits of diagnosing or treating health problems with ionizing radiation will outweigh these risks. These procedures only deliver radiation to the area that needs imaging, protecting all other parts of the body, and should always use the lowest amount of radiation needed to create a good quality image (referred to as “as low as reasonably achievable” – ALARA).

Talk to your healthcare provider and radiologist about the specific benefits and risks of the procedure recommended for your specific situation. These are some of the general benefits and risks for imaging that uses radiation:

Benefits

• Gives healthcare providers a better view of organs, blood vessels, tissues, and bones.
• Provides detailed information to help decide whether surgery is a good treatment option.
• Can be used to guide medical procedures to place catheters, stents, or other devices inside the body (fluoroscopy, a type of imaging).

Risks

• Each procedure contributes to a slight increase in the likelihood that you could develop cancer later in life.
• Fluoroscopy for guiding surgery uses higher doses of radiation than other imaging procedures and may cause skin reddening and hair loss.
• Some imaging procedures require you to drink or receive an intravenous (IV) contrast dye. This non-radioactive dye helps the radiologist see specific organs or parts of the body. Some people can have an allergic reaction to the dye.

How to Limit Your Exposure

The best way to make sure you are not getting more exposure to radiation than necessary from imaging studies is to keep track of imaging procedures and make sure each healthcare provider or specialist you see receives your results. This includes sending previous imaging results to any new healthcare provider before your visit.

It is important to tell your healthcare provider and the radiologist if you are pregnant or think you could be pregnant.

To help reduce your exposure and to help decide what type of imaging or testing is best for you, consider asking your health care provider:

• Do any of my recent tests provide the imaging needed?
• Are there other tests that do not use radiation that can provide the needed information?

For your procedure, the radiologist will use the lowest amount of radiation needed and these doses are further reduced for children. During the procedure you will often receive a lead protective shield to prevent other areas of your body that don’t need imaging from being exposed to radiation.

Other medical radiation experts include the following:

• Hospital radiation safety officer
• Medical physicist
• Radiation physicist
• Diagnostic medical physicist

Imaging Procedures That Don’t Use Radiation

Some alternative imaging procedures that do not use ionizing radiation include Magnetic Resonance Imaging (MRI) and ultrasound.

MRI procedures use magnetic fields and radio waves to produce images of specific parts of the body. Ultrasound imaging uses high-frequency sound waves to see inside the body.

You and your healthcare provider will select the best type of imaging procedure for your situation and make sure the potential benefits to your health outweigh possible risks from the procedure.

Microwave ovens use electromagnetic waves that penetrate food, causing some molecules to vibrate and generate heat which is transferred throughout the food.

Radiation Facts

• Microwave ovens use electromagnetic radiation.

• Microwaves do not make food radioactive.

About Non-Ionizing Radiation Used in Microwave Ovens

Microwave ovens use electromagnetic radiation to heat food. The non-ionizing radiation used by a microwave does not make the food radioactive. Microwaves are only produced when the oven is operating. The microwaves produced inside the oven are absorbed by food and produce the heat that cooks the food. Microwave ovens are constructed to ensure the electromagnetic radiation does not leave the oven. This includes safety interlocks which ensure that the oven turns off anytime the door is opened. Most injuries from microwave ovens are the result of heat related burns from overheated food or liquids.

If microwave ovens are used while broken or altered, it is possible for them to leak electromagnetic radiation. Microwave radiation leaks are hard to detect because you can't smell or see microwaves. The U.S. Food and Drug Administration (FDA), which regulates radiation-emitting products such as microwave ovens, advises against standing directly in front of or up against the oven while it is operating. This will avoid harm from any possible leaks.

What you can do

• Follow the manufacturer's instruction. Products will contain a safety manual and safety precautions specific to your microwave oven model.
• Never operate if broken. Don’t use a microwave oven if you can't shut the oven door or it doesn't seal well.
• Take precautions. As an added safety precaution, don't stand directly against or in front of an oven while it is operating.

On Earth, we are constantly exposed to low levels of radiation. One natural source of radiation is from space. This type of radiation is called cosmic radiation.

What is cosmic radiation?

One natural source of radiation is from space.

Cosmic radiation consists of high-energy charged particles, x-rays and gamma rays produced in space. Charged particles react with the earth’s atmosphere to produce secondary radiation which reaches the earth.

Cosmic radiation is produced by the stars, including our own sun.

Another form of radiation that comes from our sun is ultraviolet (UV) radiation. UV radiation is not considered cosmic radiation. Unlike cosmic radiation, UV radiation is lower in energy and is considered non-ionizing radiation.

Radiation dose due to cosmic radiation will vary with altitude. Higher altitudes mean greater exposure to cosmic radiation. Cosmic radiation is more intense in the upper atmosphere and most intense in deep space.

The average annual dose or exposure from cosmic radiation is 0.33 mSv (33 mrem) or 11% of a person’s yearly exposure due to all natural sources of radiation. This yearly amount of radiation is similar to the amount of radiation from three chest x-rays.

Average Annual Dose for Natural Sources of Radiation

Average Annual Dose for Natural Sources of Radiation

Radioactive materials are all around us and can be naturally found in the earth. This type of radiation is called terrestrial radiation.

We are exposed to radioactive materials in the earth when they are breathed in (inhaled) or eaten (ingested) (internal radiation) and through our skin (terrestrial external radiation).

Internal Radiation from the Earth

What is internal radiation?

Once inside the human body, the decay of radioactive materials results in a radiation dose, and this is referred to as internal radiation

Radioactive materials from the earth can enter into the human body by being inhaled (breathed in) or ingested (eaten).

Inhalation

The naturally occurring radioactive element uranium can break down and change into an odorless, colorless gas known as radon. Radon can be found in rocks, soil, groundwater (well water) and building materials all around us. When radon is released into the environment, we can breathe it in.

Ingestion

Naturally occurring radioactive elements such as carbon, potassium, uranium, thorium, and radium can be found in the soil and find their way into our food and drinking water and can be ingested.

You can also ingest radon through the water supply. However, ingesting radon poses less of a threat than inhaling it. Radon in groundwater can also contribute to radon levels in indoor air.

How much internal radiation am I exposed to?

Inhalation

On average, a person in the United States inhales enough radioactive materials to cause a radiation dose of 2.28 mSv (228 mrem) per year. About 73% of a person’s yearly exposure to natural sources of radioactive material comes from inhalation. This is mostly in the form of radon, which is the largest source of natural radiation exposure. This yearly amount of radiation is similar to the amount of radiation from twenty chest x-rays.

Ingestion

The overall levels of ingested radioactive materials are low for most people. On average, a person in the United States ingested enough natural sources of radiation to cause a small dose of about 0.29 mSv (29 mrem) per year. About 9% of a person’s yearly exposure to natural sources of radioactive material comes from ingestion. This yearly amount of radiation is similar to the amount of radiation from two chest x-rays.

Average Annual Dose for Natural Sources of Radiation

Average Annual Dose for Natural Sources of Radiation

Reference: National Council on Radiation Protection and Measurements. NCRP Report No. 160, Ionizing Radiation Exposure of the Population of the United States. https://ncrponline.org/publications/reports/ncrp-report-160/

What is the risk from internal radiation we get from the earth?

Unless food products are contaminated as the result of a radiation emergency, levels of ingested radioactive material in the environment are low and are unlikely to affect human health. Inhaled radioactive material in the form of radon could affect health, and radon levels in buildings should be tested and fixed if they are elevated.

The amounts of radon you are exposed to may differ depending on where you live. Having your home tested is the only effective way to determine whether you or your family is at risk of radon exposure.

External Radiation from the Earth (Terrestrial External Radiation)

What is terrestrial external radiation?

Every day we are exposed through our skin to external radiation from the earth. Terrestrial external radiation is due to the decay of radioactive materials in the earth itself.

Terrestrial external radiation is created by the process of the natural breakdown—or radioactive decay—of radioisotopes in natural materials such as rocks, soil, vegetation, and groundwater. Radioactive decay is a natural process and has taken place since the beginning of time.

Radioactive materials in the earth expose us directly to radiation in a manner similar to the exposure from a medical x-ray.

How much terrestrial external radiation am I exposed to?

The overall levels of terrestrial external radiation are low. The average annual dose due to terrestrial external radiation exposure is 0.21 mSv (21 mrem) or 7% of a person’s yearly exposure due to all natural sources. This yearly amount of radiation is similar to the amount of radiation from two chest x-rays.

Average Annual Dose for Natural Sources of Radiation

Average Annual Dose for Natural Sources of Radiation

Reference: National Council on Radiation Protection and Measurements. NCRP Report No. 160, Ionizing Radiation Exposure of the Population of the United States. https://ncrponline.org/publications/reports/ncrp-report-160/

What is the risk from terrestrial external radiation?

Overall levels of terrestrial external radiation are low and are unlikely to affect human health.

Radiation can naturally come from the sun through ultraviolet (UV) radiation

Ultraviolet (UV) radiation is a form of non-ionizing radiation that is emitted by the sun and artificial sources, such as tanning beds. The beneficial effects of UV radiation include the production of a vital nutrient, vitamin D; however, overexposure may present risks. Sunburn, premature aging, and skin cancer are all risks to overexposure. Keeping you and others protected from UV radiation is an important, year-round responsibility.

What are sources of UV radiation?

• Our natural source includes:
  • The sun
• Some artificial sources include:
  • Tanning Beds
  • Mercury vapor lighting (often found in stadiums and school gyms)
  • Some halogen, fluorescent, and incandescent lights
  • Some types of lasers

What are the different types of UV radiation rays?

UV radiation is classified into one of three primary groups: ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). This grouping is based on the measure of their wavelength, which is measured in nanometers (nm= 0.000000001 meters or 1×10 meters).

UV Radiation

All of the UVC and most of the UVB radiation is absorbed by the earth’s ozone layer, so nearly all of the ultraviolet radiation received on Earth is UVA. Even though UVA radiation is weaker than UVB, it penetrates deeper into the skin and is more constant throughout the year. Since UVC radiation is absorbed by the earth’s ozone layer, it does not pose as much of a risk.

What are the risks and benefits of UV radiation?

Benefits:

• Beneficial effects of UV radiation include the production of vitamin D, a vitamin essential to human health. Vitamin D helps the body to absorb calcium and phosphorus from food and assists in bone development. The World Health Organization (WHO) recommends 5 to 15 minutes of sun exposure 2 to 3 times a week. Additional information can be found here.
• Artificial forms of UV radiation (lasers, lamps, or a combination of these devices) used with some topical medications that increase UV sensitivity are sometimes used to treat patients with certain diseases who have not responded to other methods of therapy. A trained healthcare professional uses this special procedure called phototherapy to treat the following:
  • Rickets
  • Psoriasis
  • Eczema
  • Vitiligo
  • Lupus

Risks:

• Sunburn is a sign of short-term overexposure, while premature aging and skin cancer are side effects of prolonged UV exposure.
• Some oral and topical medicines, such as antibiotics, birth control pills, and benzoyl peroxide products, as well as some cosmetics, may increase skin and eye sensitivity to UV in all skin types.
• UV exposure increases the risk of potentially blinding eye diseases, if eye protection is not used.
• Overexposure to UV radiation can lead to serious health issues, including cancer. Skin cancer is the most common cancer in the United States. The two most common types of skin cancer are basal cell cancer and squamous cell cancer. Typically, they usually form on the head, face, neck, hands, and arms because these body parts are the most exposed to UV radiation. Most cases of melanoma, the deadliest kind of skin cancer, are caused by exposure to UV radiation.

Anyone can get skin cancer, but is more common in people who:

• Spend a lot of time in the sun or have been sunburned
• Have light-color skin, hair and eyes
• Have a family member with skin cancer
• Are over age 50

Changes in your skin are the most common signs of skin cancer.

How do I protect myself from UV radiation?

Keeping yourself and others protected from UV radiation is an important, year-round responsibility, not just at the beach or during the summer months. To protect yourself from UV radiation:

• Stay in the shade, especially during midday hours.
• Wear clothes that cover your arms and legs.
• Wear a hat with a wide brim to shade your face, head, ears, and neck.
• Wear sunglasses that wrap around and block both UVA and UVB rays.
• Use sunscreen with sun protection factor (SPF) 15 or higher, and both UVA and UVB protection.
• Avoid indoor tanning. Indoor tanning is particularly dangerous for younger users; people who begin indoor tanning during adolescence or early adulthood have a higher risk of developing melanoma.

Also remember to protect your children.

The UV Index scale helps us understand how harmful UV radiation can be on a given day. This useful tool forecasts the strength of the sun’s harmful rays. Remember, the higher the number, the greater chance of overexposure leading to health concerns.

What are wearable computers and wearable technology?

Wearable computers and wearable technology are small devices using computers and other advanced technology that are designed to be worn in clothing or directly against the body. These devices are usually used for entertainment and other tasks like monitoring physical activity.

Wearable technology typically uses low-powered radiofrequency (RF) transmitters to send and receive data from smartphones or the Internet. RF transmitters emit radiowaves, a type of non-ionizing radiation.

Most devices use low-powered Bluetooth technology similar to that used in “hands free” headsets for cell phones and many other wireless consumer devices. Some devices may use Wi-Fi or other communication technologies as well.

What are some examples of wearable computers and wearable technology?

• Familiar examples of wearable computers or wearable technology include “smartwatches” and fitness trackers. Future devices could include head-mounted displays and a wide variety of personal health monitors.
• Wearable Technology and Safety
• RF transmitters in wearable technology expose the user to some level of RF radiation. RF radiation is a form of non-ionizing radiation made up of radiowaves.
• RF transmitters in wearable devices operate at extremely low power levels and normally send signals in streams or brief bursts (pulses) for a short period of time. As a result, wearable devices expose the user to very small levels of RF radiation over time.

How much RF radiation am I exposed to?

To be sold in the U.S., equipment that transmits RF radiation must meet exposure limits set by the Federal Communications Commission (FCC). These limits are designed to reduce exposure to RF radiation.

For more information on FCC regulations around RF radiation, click here

While the FCC guidelines were adopted in 1996, they are similar to international guidelines that are presently in effect in many other countries. Wearable devices expose the user to small amounts of RF radiation compared to these international exposure limits [PDF – 647kb].

Wearable technology can distract you

If you use wearable devices, it could be a source of distraction and raise a number of safety and other issues unrelated to RF radiation exposure. This is a major concern if you are driving a car or participating in other activities that require close attention.

What You Need to Know

• Most wearable devices include low-powered RF transmitters to enable them to communicate with other devices.
• To be sold in the U.S., all such devices must meet FCC limits for human exposure to RF radiation.
• Wearable devices expose the user to lower amounts of RF radiation compared to international exposure limits.
• Wearable electronics may distract the user and increase the chances of injury while driving or using dangerous equipment.
• CDC continues to monitor this topic.

If you are injured or think you are injured, seek medical attention right away. Injuries could be at high risk for infection and other long lasting health effects.

Radioactive contamination and radiation exposure could occur if radioactive materials are released into the environment as the result of an accident, an event in nature, or an act of terrorism. Such a release could expose people and contaminate their surroundings and personal property.

Short-Term Health Effects of Radiation Exposure and Contamination

• Acute Radiation Syndrome. Radiation sickness, known as acute radiation syndrome (ARS).
• Cutaneous Radiation Injury (CRI). Happens when exposure to a large dose of radiation causes injury to the skin.

Long-Term Health Effects of Radiation Exposure and Contamination

• Cancer. People who receive high doses of radiation could have a greater risk of developing cancer later in life, depending on the level of radiation exposure.
• Prenatal Radiation Exposure. It is especially important that pregnant women follow instructions from emergency officials and seek medical attention as soon as emergency officials say it is safe to do so after a radiation emergency.
• Mental Health. Any emergency, including those involving radiation, can cause emotional and psychological distress.