Skin Cancer & UV
In this section you can learn about skin cancer and its primary cause, UV radiation. Find answers to common questions by clicking on the links below:
About Skin Cancer
- How common is skin cancer?
- How common is melanoma in Colorado?
- Are there different types of skin cancer?
- What does skin cancer look like?
- Who is at risk?
- Where you live
- Who you are
- What you do
- What does skin cancer cost to treat?
- Can skin cancer be prevented?
About UV Rays
- What are UV rays?
- Are there different kinds of UV rays?
- How do UV rays damage the skin?
- How does the sun cause eye damage?
- Are tanning beds safe?
- What determines UV intensity?
- What is the UV Index?
- What’s the UV Index for my city?
- How can overexposure to UV rays be avoided?
- Should schools be concerned about ultraviolet (UV) radiation?
- What does SPF mean?
- Is teaching sun safety important?
- Do I need to reapply water-resistant sunscreen after my students go swimming?
- Why do students get sunburned even when it's cloudy?
- How common are sunscreen allergies?
About Skin Cancer
How common is skin cancer?
This year more than one million Americans will be diagnosed with skin cancer. That's more than all other types of cancer combined. Over 10,000 Americans (more than one per hour) will die from the disease.
The incidence of malignant melanoma in the U. S. has been increasing faster than any other type of cancer and has doubled since 1973. The annual incidence rate of melanoma in Colorado is higher than the national average. This year in Colorado, it is estimated that there will be 1,180 new cases of melanoma and 128 deaths from the disease.1
1National Cancer Institue, American Cancer Society
Source: NCI SEER Stats (statecancerprofiles.cancer.gov); Cancer in Colorado: 1992-2002
- Squamous cell carcinoma
- Basal cell carcinoma
Each of these cancers is named for the type of skin cell from which it arises. Melanoma is a malignancy of the skin’s pigment-producing cells or melanocytes. Squamous cell carcinoma is a malignancy of the cells of the middle or upper epidermis, while basal cell carcinoma occurs when the cells at the base of the epidermis turn malignant.
Melanoma is less common than the other two types of skin cancer, but is far more deadly. It is almost always curable in its early stages, but because of its potential to metastasize (spread to other regions of the body), early detection and treatment are crucial.
Squamous cell carcinoma is not as aggressive as melanoma. Cure rates are in excess of 95% when the tumor is detected and treated early. Chronic overexposure to the sun, as might occur with outdoor employment is a major cause. Actinic keratosis (AK) is a very common skin lesion which is now recognized as the earliest stage in the development of skin cancer. Left untreated, these lesions can progress to squamous cell carcinoma.
Basal cell carcinoma is the most common and least aggressive type of skin cancer. However, it can be quite destructive and has the potential to spread if left untreated.
What does skin cancer look like?
Melanoma most commonly has the appearance of an unusual mole. It frequently exhibits the “ABCDE’s” of: Asymmetry, Border irregularity, Coloration which is dark or in multiple shades, Diameter the size of a pencil eraser or larger, and Evolving, or changing over time - look out for any mole that is new, enlarges, changes shape, darkens or begins to look odd compared to typical moles. Melanoma can appear on previously normal skin, or can develop in a pre-existing mole.
Squamous cell carcinoma usually appears as a reddish-colored firm lump or plaque with a scaly surface. Actinic keratosis (a precursor of squamous cell carcinoma) is a small pinkish scaly patch. Each of these irregularities is most commonly found on areas of the body that have been chronically exposed to the sun, such as the face, ears, hands, and the scalp of bald men or women.
Basal cell carcinoma, in its classic form, is a small bump with a translucent quality. It is somewhat red due to enlarged “bloodshot” vessels on its surface. As it grows larger, the surface often ulcerates or forms a scab.
Who is at risk?
Did you know the three major factors that increase your risk of developing skin cancer? The first, intense UV exposure that leads to sunburn; and accumulated UV exposure that results in tanned skin. Second, family history and whether skin cancer runs in your family. Third, skin type or how easily you burn.
Where you live
Areas closer to the equator, higher in elevation and with many dry, sunny days increase the UV exposure people receive each day. Most regions of Colorado are not only at higher elevations, but also have 300+ sunny days each year. This means that if you live, work or play here, you have to be concerned about sun safety. Also, remember that if you are in the mountains, you have even less protection from UV. At an altitude of 10,000 feet, UV is 50 percent more intense than at sea level.
Who you are
Fair-skinned and fair-haired people with light eyes and many moles are at the highest risk, but no matter the color of one's skin it is still possible to develop skin cancer. Make sure that all employees recieve sun safety training.
What you do
Your work and extracurricular activities have an effect on your skin cancer risk. Think about the choices you make. Do you sunbathe to get a tan? Do you visit tanning salons before going on vacation? Do you use various forms of sun protection while spending time outdoors?
Skin's susceptibility to burning can be determined on a six-point scale as shown in the following table1:
Though everyone is susceptible to damage as a result of excessive sun exposure, people with skin types I and II are at highest risk.
|Skin Type||Tanning and Sunburning History|
|I||Always burns, never tans, sensitive to sun exposure|
|II||Burns easily, tans minimally|
|III||Burns moderately, tans gradually to light brown|
|IV||Burns minimally, always tans well to moderately brown|
|V||Rarely burns, tans profusely to dark|
|VI||Never burns, deeply pigmented, least sensitive|
1 Fitzpatrick TB. Arch Dermatol. Jun 1988:124(6):869-71.
What does skin cancer cost to treat?
While most skin cancer is curable with minor surgery, the sheer number of cases makes this a very costly disease. The 2004 tab for treating skin cancer and actinic keratosis in the U.S. was $2.9 billion according to the Society of Investigative Dermatology and the American Academy of Dermatology. This does not include the indirect costs of lost productivity or decreased quality of life. Sun protection would not only help to prevent human suffering, but would significantly reduce health care costs as well.
Can skin cancer be prevented?
Yes! Skin cancer is largely preventable by avoiding overexposure to UV radiation. Most people attain up to 25% of their lifetime sun exposure before their 18th birthday1 and just two or more blistering sunburns during adolescence nearly doubles the risk of melanoma.2
Remember these prevention strategies:
- Seek Shade
- Cover Up
- Long-sleeved shirts and long pants
- Wear UPF clothing
- Use Sunscreen
- Avoid tanning beds and lamps
1Godar, DE: UV doses of young adults. Photochem and Photobiol. 2003;77(4):453-457
2Weinstock MA, Colditz GA, Willett WC, et al. Pediatrics. Aug1989;84(2):199-204
About UV Rays
What are ultraviolet (UV) rays? UV rays are invisible waves of radiation generated by the sun. While some of the sun’s radiation is in the form of visible light and heat, UV rays are shorter in length. This shorter wavelength gives UV its capacity to penetrate into the skin. The one beneficial result is the conversion of vitamin D into its active form. However, UV rays are also just the right length to damage cells and to act as a human carcinogen.
Are there different kinds of UV rays?
Yes. Ultraviolet radiation is actually a continuous spectrum of wavelengths which scientists have divided into three categories, UVA, UVB, and UVC. Rays with the longest wavelength are designated as UVA. UVB rays are shorter, and UVC rays are the shortest of all. Because ozone in the atmosphere absorbs all UVC and most UVB, 95 percent of the radiation reaching the surface of the earth is UVA while just 5% is UVB. UVB penetrates only into the epidermis (upper layer) of the skin but is the major cause of sunburns. UVA penetrates more deeply, down into the dermis of the skin. Tanning beds emit mostly UVA, however both UVA and UVB are highly damaging and can cause skin cancer.
How do UV rays damage the skin?
When ultraviolet radiation strikes the skin, the rays penetrate beneath the surface and can damage an epidermal cell’s genetic material, or DNA. While the body can usually repair the damage, sometimes this mechanism fails, resulting in a mutation. The skin cancer that can result is named for the type of cell where the mutation occurred. For example, melanoma is a tumor of malignant melanocytes.
UV rays can also damage the dermis and suppress the skin’s immune system, both of which contribute to cancer formation in the epidermis above. Solar damage to the dermal collagen and elastic fibers is a major contributor to skin aging, manifested as wrinkling and sagging.
A helpful rule of thumb is: “A (UVA) is for aging, B (UVB) is for burning.” Check out the diagram below for better understanding of UVA and UVB.
When UVB rays penetrate into the skin, they are just the right wavelength to be absorbed by the cell’s genetic material, or DNA. Such bombardment of the DNA can cause it to break apart. While the body can repair most of these molecular injuries, sometimes this mechanism fails, especially in the case of a large dose of radiation, such as a sunburn. This results in mutations which can lead to cancer.
UVA rays penetrate more deeply. They contribute to the formation of skin cancer by inhibiting the tumor suppressive action of the body’s immune cells in the dermis.
In addition to causing skin cancer, damage done by UV exposure includes:
- Dark blotches
- Rough texture
- Skin thinning and sagging
- Cataracts in the eyes
How does the sun cause eye damage?
Overexposure to the sun also can damage your eyes and cause cataracts, macular degeneration and melanoma of the eye. With cataracts, the lens of the eye becomes thick and cloudy, resulting in reduced vision or blindness. According to the World Health Organization, 16 million people worldwide are currently blind as a result of cataracts and as many as 20% of these may be due to UV exposure.
Are tanning beds safe?
No. UVA is the predominant wavelength provided by most tanning beds. Don’t be fooled just because UVA is less likely to cause sunburn than UVB. The ultraviolet radiation emitted by tanning lights is declared to be a known human carcinogen by the U.S. Government. There is no safe dose of a carcinogen. The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), as well as the American Academy of Dermatology (AAD), encourage people to avoid using tanning beds or sun lamps.
Recently the Federal Trade Commission investigated deceptive advertising practices associated with the indoor tanning industry. It found the industry did not properly disclose potentially harmful health concerns such as skin cancer risk, when using tanning beds. Click here to read the report.
For more information check out these resources:
Time of Year: The sun's angle varies with the seasons, causing the intensity of UV rays to change. UV intensity tends to be highest during the summer months.
Time of Day: The amount of UV varies throughout the day. The period of highest danger is between 10 a.m. and 4 p.m.
Scattered and Reflected UV Rays: UV rays reflect off snow, water, sand, and concrete. Thin cloud cover scatters UV rays in all directions and allows UV rays to reach your skin even when you are wearing a hat or are under an umbrella.
Altitude: UV rays are more intense at higher altitudes because the thinner atmosphere filters out fewer UV rays. UV rays increase approximately 4% with every 1,000 feet above sea level.
Latitude: UV rays are strongest close to the equator because the sun is more directly overhead. UV rays must travel through less ozone before hitting the earth in these areas. The ozone layer is also naturally thinner in the tropics. At higher latitudes, the UV rays enter the ozone layer at an angle, which decreases UV intensity.
Climate/weather: Clouds block some UV rays from hitting the earth and decrease the UV intensity. However, clouds do not block all UV rays and it is possible to sunburn on cloudy days.
What is the UV Index?
The UV Index was developed by the National Weather Service and the Environmental Protection Agency. It provides a forecast of the expected risk of overexposure to UV rays and indicates the degree of caution you should take when outdoors. It predicts exposure levels on a 0 to 11+ scale, where values of 2 or less indicate a low danger, while 11+ signifies an extreme risk of harm from unprotected sun exposure. Get in the habit of checking the UV index. It is available online and printed on the weather page of many newspapers.
|UV Index||Expected Risk and Precautions|
|2 or less:
A UV Index reading of 2 or less means low danger from the sun's UV rays for the average person:
A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.
A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Apply a sunscreen with an SPF of at least 15. Wear a wide-brim hat and sunglasses to protect your eyes.
A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Minimize sun exposure during midday hours, from 10 a.m. to 4 p.m. Protect yourself by liberally applying a sunscreen with an SPF of at least 15. Wear protective clothing and sunglasses to protect the eyes.
A UV Index reading of 11 or higher means extreme risk of harm from unprotected sun exposure. Try to avoid sun exposure during midday hours, from 10 a.m. to 4 p.m. Liberally apply sunscreen with an SPF of at least 15 every 2 hours.
How can overexposure to UV rays be avoided?
We cannot stay completely out of the sun. There will be many occasions when we need or desire to be outdoors for exercise, work, or recreation. However, by taking relatively simple steps, most sun damage can be avoided.
- Whenever you are outdoors, consider the potential for sun damage
- Be aware of your skin type. People with Skin Type I or II (link: table above) are most vulnerable and should be especially careful
- Check the UV Index forecast and follow the accompanying EPA recommendations
- Limit unnecessary sun exposure between 10 a.m. and 4 p.m.
- Seek shade when available
- Cover up by wearing a wide-brimmed hat, long-sleeved shirt, long pants and sunglasses
- Use sunscreen and lip balm with SPF 15 or higher
Should schools be concerned about ultraviolet (UV) radiation?
UV radiation is recognized by Congress, the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA) and other agencies as a know human carcinogen. Schools have taken steps to minimize exposure to other harmful substances such as asbestos, radon and lead on school grounds and UV radiation should be no different. The sun’s UV radiation presents both a recreational and occupational hazard to students and staff so steps should be taken to prevent overexposure. Educating students and staff members about sun safety may help reduce possible liabilities in the future.
What does SPF mean?
SPF stands for Sun Protection Factor. Something that many people are unaware of is that SPF is a greater predictor of the length of protection rather than the strength of protection. To find out more visit the Sunscreen section.
Is teaching sun safety important?
Yes, teaching sun safety to students provides them with the knowledge and skills they need to make health conscious choices when spending time in the sun. Given the large percentage of time that students spend outdoors, it is important to teach sun safety and to reinforce the messages throughout the year.
Do I need to reapply water-resistant sunscreen after my students go swimming?
Yes. It is very important to reapply sunscreen after you get wet, whether in a pool, running through the sprinkler or sweating a lot at soccer practice, even water-resistant sunscreens. Also, remember to reapply every two hours to keep the sunscreen potent.
Why do students get sunburned even when it's cloudy?
Clouds only block 20-40% of damaging UV rays. That means that as much as 80% of UV rays reach your skin even on cloudy days. Check the UV Index for a reading of the day’s UV forecast to help you plan for a sun safe day. The UV Index can be found in your local newspaper or you can check the UV index in your area by inserting your zip code.
How common are sunscreen allergies?
Fortunately, allergic reaction to sunscreen is very uncommon and, if one does occur, it is generally a minor reversible skin rash. Less than 1% of people have some reaction to some ingredients in certain sunscreens. Hypoallergenic and fragrance-free products are good choices especially for people already known to have skin allergies. PABA which was responsible for many people’s allergic reaction has been removed from most sunscreens.
Before a teacher puts sunscreen on their student, they should check with the student's parents about possible allergies.
If you have further questions you would like answered, send an email to the experts.