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UV (ultraviolet) radiation is a type of electromagnetic radiation. Like all radiation, UV radiation is energy that spreads as it travels. Exposure to UV, either from the sun or other sources, is a major risk factor for skin cancer.
Different types of radiation are described by the amount of energy particles (photons) they have and give off.
There are different types of UV rays, based on how much energy they have. They are all a type of electromagnetic radiation, which is energy that travels in waves at the speed of light. UV is close to the middle of the electromagnetic spectrum, just above visible light.
Image courtesy of fda.gov
Types of electromagnetic radiation that are lower in energy (lower frequency) include microwaves and radio waves. Higher energy (higher frequency) radiation includes x-rays and gamma rays.
Higher energy types of radiation are called ionizing radiation. This means they have enough energy to remove an electron from (ionize) an atom or molecule. Ionizing radiation can damage the DNA (genes) in cells, which in turn may lead to cancer.
Some higher types of UV radiation are ionizing, but even the highest-energy UV rays don’t have enough energy to penetrate deeply into the body, so their main effect is on the skin.
UV radiation is divided into 3 main groups:
Sunlight is the main source of UV radiation and both UVA and UVB rays can damage your skin. This is because the different types of UV rays reach the ground in different amounts. About 95% of the UV rays from the sun that reach the ground are UVA rays, with the remaining 5% being UVB rays.
The amount of UV exposure a person gets depends on the strength of the rays, the length of time the skin is exposed, and whether the skin is protected with clothing or sunscreen. To learn more, see What Factors Affect UV Risk?
People can also be exposed to artificial sources of UV rays. These include:
Exposure to UV rays, whether from sunlight or tanning devices, is a risk factor for all types of skin cancer. The risk is higher for people with a weakened immune system, a personal or family history of skin cancer, and if they have large or many moles on their skin.
Most skin cancers are a result of exposure to the UV rays in natural sunlight.
Skin cancer has also been linked to exposure to some artificial sources of UV rays, including tanning devices.
Many studies have found that basal and squamous cell skin cancers are linked to certain behaviors as well as a history of having sunburns and sun-related skin damage, such as:
Studies have also found links between certain behaviors and sun exposure and melanoma of the skin, including:
Because UV rays don’t penetrate deeply into the body, they have not been found to cause cancer in internal organs. However, some studies have shown possible links between UV rays and some other cancers, including Merkel cell carcinoma (a less common type of skin cancer) and melanoma of the eye.
Studies have found that people who use tanning beds (or booths) have a higher risk of skin cancer, including melanoma and squamous and basal cell skin cancers.
The risk of melanoma is about 60% higher if a person starts indoor tanning before age 35. And, the risk of basal and squamous cell skin cancer is higher if indoor tanning started before age 25.
In general, the American Cancer Society does not determine if something causes cancer (that is, if it is a carcinogen), but we do look to other respected organizations for help with this. Based on the available evidence, several expert agencies have evaluated the cancer-causing (carcinogenic) nature of UV radiation.
The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO). One of its major goals is to identify causes of cancer. Based on the available data, IARC has made the following determinations:
The National Toxicology Program (NTP) is formed from parts of several different US government agencies, including the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA). The NTP has made the following determinations:
The US Food and Drug Administration (FDA), which refers to all UV lamps used for tanning as “sunlamps,” requires them to carry labels that:
(For more information on the classification systems used by these agencies, see Determining if Something Is a Carcinogen.)
The American Academy of Dermatology Association (AADA) has a position statement about indoor tanning that states the AADA:
In addition to skin cancer, exposure to UV rays can cause other health problems:
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
American Academy of Dermatology (AAD). Sun protection. Accessed at https://www.aad.org/public/everyday-care/sun-protection on June 26, 2024.
Baron ED. Selection of sunscreen and sun-protective measures. UpToDate. 2024. Accessed at https://www.uptodate.com/contents/selection-of-sunscreen-and-sun-protective-measures on June 26, 2024.
Centers for Disease Control and Prevention (CDC). Sun safety. 2023. Accessed at https://www.cdc.gov/cancer/skin/basic_info/sun-safety.htm on June 26, 2024.
Centers for Disease Control and Prevention (CDC). Skin Cancer Prevention Progress Report. 2019. Accessed at https://stacks.cdc.gov/view/cdc/81911 on June 26, 2024.
Davis KE. The dangers of indoor tanning. Journal of Derm Nurs Assoc. 2023;15(3):120-122.
International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Vol. 100D: Solar and Ultraviolet Radiation. 2012. Accessed at: https://publications.iarc.fr/121 on June 26, 2024.
Morais P. Artificial tanning devices (sunbeds): Where do we stand? Cutaneous & Ocular Toxicology. 2022;41(2):123-128.
Skin Cancer Foundation. Sun protection. Accessed at https://www.skincancer.org/skin-cancer-prevention/sun-protection/ on June 26, 2024.
US Department of Health and Human Services. The Surgeon General’s Call to Action to Prevent Skin Cancer. 2014. Accessed at https://www.ncbi.nlm.nih.gov/books/NBK247163/ on June 26, 2024.
US Food and Drug Administration (FDA). Sunlamps and sunlamp products (tanning beds/booths). 2020. Accessed at https://www.fda.gov/radiation-emitting-products/home-business-and-entertainment-products/sunlamps-and-sunlamp-products-tanning-bedsbooths on June 26, 2024.
US Food and Drug Administration (FDA). The Risks of Tanning. 2023. Accessed at https://www.fda.gov/radiation-emitting-products/tanning/risks-tanning on June 26, 2024.
US National Toxicology Program (NTP). 15th Report on Carcinogens: Ultraviolet-Radiation-Related Exposures. 2021. Accessed at https://ntp.niehs.nih.gov/sites/default/files/ntp/roc/content/profiles/ultravioletradiationrelatedexposures.pdf on March 5, 2024.
Last Revised: June 26, 2024
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