Skin Safety

Protecting our skin from harmful ultraviolet (UV) light is a year-round job. It requires wearing the proper clothing, using sunscreen on exposed skin, and seeking shade when the sun’s rays are at their strongest. 

But have you ever wondered what distinguishes regular, everyday clothing from the kind you see advertised as having a UPF, or Ultraviolet Protection Factor? Or, the difference between UPF and SPF, which is listed on bottles of sunscreen and other skin care products?

For answers to these and five other questions, we went to dermatologist Valencia Thomas, M.D., who serves as director of MD Anderson’s Mohs Center. Here’s what she shared with us.

What’s the difference between SPF and UPF?

• SPF, or Sun Protection Factor, is based on the amount of time it takes for skin to start turning red after being exposed to UV light. The number indicates how many times longer than that a product applied to the skin might protect you, if used properly. So, if you’d normally start to burn after about 10 minutes out in the sun, sunscreen with SPF 30 could theoretically extend that period by 30 times — or for up to five hours (300 minutes).
• UPF, or Ultraviolet Protection Factor, meanwhile, is a measurement of the amount of UV light that can reach your skin through a particular fabric. The number here represents the bottom part (denominator) of a fraction. So, if a bucket hat is advertised as having UPF 50+ protection, that means only about 1/50^th of the sun’s UV rays — or 2% — can pass through it.

Another difference is that UPF blocks both UVA and UVB light. Unless a product is labeled “broad spectrum” though, SPF technology only blocks UVB light. UVB light is the type that causes most sunburns and skin cancers. UVA light causes wrinkles and other visible signs of aging.

Why did you use the word “theoretically” when talking about SPF?

I don’t want to give anyone a false sense of security. And, I also don’t want anyone who burns really easily doing the math and thinking they can stay on the beach for hours without any problem, just because they put on SPF 30 sunscreen once and never reapplied it.

The key phrase above was “if used properly.” Most people only apply about one-third of the sunscreen they actually need. They use one tablespoon per application, when you really need three. That’s the equivalent of a quarter cup!

Also, both swimming and sweating can make sunscreen wear off much faster, so it needs to be reapplied frequently. We recommend reapplying sunscreen at least once every two hours, but more often if you’re playing in the water or perspiring profusely.

How does clothing made specifically to protect skin from UV light differ from regular clothing? 

What makes these fabrics special is the material they’re made out of, how tightly they’re woven and, sometimes, how they’re processed. Many of these garments are woven very tightly to block the sun’s rays. Others are dyed with or soaked in special chemical solutions that basically give the fabric a natural sunscreen, such as zinc oxide. 

Applied coatings can fade over time, though. So, you may notice the colors changing or the fabrics getting stretchier as you wash these garments. Those could be signs that they’re losing their UPF protection and need to be replaced. 

Check the label of each item or visit the manufacturer’s website for details. Some garments are designed to retain their UPF for up to 100 or even 500 washes. Other manufacturers claim their garments’ UV protection never wears out. 

Doesn’t regular clothing protect us against UV light?

Your clothing’s UPF value depends on the type of fabric it’s made out of, the color of the fabric and whether or not the fabric is wet. Dry, tightly woven, dark-colored fabrics offer the most protection. 

But the stretchier a fabric is, the less protection it offers, especially when fully extended. Something like dry, dark biking shorts start out at about UPF 85 before the material is stretched, and UPF 8 when worn. And, if they get wet, too, they drop even more, to UPF 4. 

A conventional bathing suit made out of dark, stretchy material has a UPF 8.6 when dry, while a white or light-colored bathing suit only offers about UPF 4 when wet. Most swimsuits provide about a UPF 5, so roughly 20% of the sun’s rays will still reach your skin.

Does that mean we should all be putting on sunscreen before we put on our swimsuits?

No. The current recommendation is to apply sunscreen only to exposed skin. Just keep in mind that traditional bathing suits might not offer as much protection to covered areas as you think. 

Most of the Mohs surgeries I perform in the buttock fold area have one thing in common: they’re all on people who are shocked. Many, however, have a history of sunning themselves face-down in a bathing suit. I also do a lot of Mohs surgeries on UV-associated cancers around sensitive genital skin, due to tanning bed use.

Is there any way to gauge how protective my regular clothing is?

Yes. One way is to hold it up to the sun. If you can see the sun’s light through the fabric, then its UV rays are getting through. But the weave of a fabric matters. So, if you have something with a very tight weave and hold it up to a window, then you might not see the sun. 

If you’re really concerned, you can always look for UPF 50+ swim garments that block 98% of the sun’s rays. It’s much easier to find swimsuits with sun-protective materials now than it used to be. It’s also much easier to buy one of those than it is to try to put sunscreen everywhere.

According to the American Academy of Dermatology, any garment with a UPF between 30 and 49 is considered good protection, while a garment with a UPF 50 or higher is considered excellent protection. Anything under UPF 30 is not considered highly sun protective. 

Is there any way to add UPF to my clothing myself?

Yes. There’s a colorless fabric dye you can use as a laundry treatment. You add one package to a load of laundry and let it soak. The effect is said to last for up to 20 washes. It’s available at most fabric and craft stores.

Request an appointment at MD Anderson online or call 1-877-632-6789.

Sunscreen is a hot topic – and not just because it’s a summertime staple!

There are also many myths and misconceptions surrounding sunscreen’s safety, effectiveness and usefulness. 

So, if you’ve ever been confused about when – or if! – to use sunscreen, you’re not alone.

We asked dermatologist Anisha Patel, M.D., about common sunscreen myths. Read on for her answers.

Myth 1: All sunscreens work the same way.

False. Sunscreens can prevent sunburn in different ways.

Chemical sunscreens: The active ingredients in chemical sunscreens absorb UV rays as they hit the skin, Patel explains.

Physical blocker sunscreens: Physical sunscreens, which are also called mineral sunscreens or sun blocks, use ingredients such as zinc oxide and titanium dioxide to form a barrier on the skin’s surface that reflects UV rays.

Not sure whether to use a chemical or physical sunscreen? Hybrid sunscreens contain both chemical absorbers and physical blockers. 

When selecting a sunscreen, MD Anderson dermatologists recommend choosing a broad-spectrum product with at least sun protection factor (SPF) 30. 'Broad spectrum' means the product protects from both UVA and UVB rays which can lead to sun damage and skin cancer. SPF refers to the amount of UVB rays it blocks.

Myth 2: It doesn’t matter what kind of sunscreen I choose.

False. While wearing sunscreen is always a good choice, each type of sunscreen has instructions that must be followed to ensure your skin is protected. 

Sunscreen comes in formats including cream, lotion, spray, powder and stick.

Each type of sunscreen has benefits and limitations. For example, many spray sunscreens are clear and absorb into the skin quickly, but this feature can make it challenging to see if you’ve missed a spot.

Overwhelmed by options? MD Anderson dermatologists recommend physical blocker sunscreens. Patel says this is because they have the broadest range of UVA and UVB protection.

Whatever type of sunscreen you choose, always review its instructions for information on how – and how frequently – to apply and reapply.

Myth 3: Sunscreen causes cancer.

False. There is no medical evidence that sunscreen causes cancer. However, there is a lot of evidence that UV rays from the sun and tanning beds do.

In the past, some sunscreens were recalled for being contaminated with a chemical called benzene. Benzene is not normally found in sunscreen. This recall doesn’t mean you should stop wearing sunscreen, dermatologists say.

Still, some may feel more comfortable using sunscreens that don't absorb into the skin – that is, those physical blockers sunscreens described above.

Additionally, sunscreen isn’t the only way you can practice sun safety.

“There are a lot of sun protective options outside of just the creams and sprays,” Patel says.

Other ways to protect yourself from sun damage include:

• Wearing protective clothing that is dark and tightly woven, with ultraviolet protection factor (UPF) 50+
• Wearing a wide-brimmed hat
• Wearing sunglasses with UVA and UVB protection
• Seeking shade between 10 a.m. and 4 p.m. when sun rays are strongest

Myth 4: I have dark skin. I don’t need to wear sunscreen.

False. Dark skin is susceptible to sun damage.

It takes more sun exposure for darker skin types to get sun damage, Patel says. She explains this is because melanin, which gives skin its color, provides DNA with a small amount of sun protection. Still, this small amount of protection doesn’t prevent sun damage altogether.

“Darker skinned people can still get a sunburn, still get skin cancers and definitely still get photoaging from UV exposure,” Patel says.

Regardless of your skin color, apply sunscreen liberally 30 minutes before going out in the sun, and don’t forget to reapply every two hours or after swimming or sweating.

Myth 5: My sunscreen is waterproof, so I don’t need to reapply it after swimming or sweating.

False. According to the Food and Drug Administration (FDA), there is no such thing as waterproof sunscreen.

There is, however, water-resistant sunscreen. The FDA writes that these products offer water-resistant sun protection according to the time and SPF level specified on each product.

Heading for a beach day or outdoor workout? Choose a water-resistant sunscreen and follow the product instructions on how often to reapply. 

Myth 6: My sunscreen is SPF 50, so I don’t need to apply it as often.

False. No matter the SPF number, chemical absorber sunscreens only work for about two hours and should be reapplied after swimming or sweating.

Regardless of the SPF level you choose, you need to reapply with the same frequency, Patel says.

If you have trouble remembering to reapply, Patel suggests using a physical blocker sunscreen. These products don’t rub in or disappear into the skin, so it is easy to determine when to reapply.

“If you can see the white on your face, it's still working,” she says.

Myth 7: There is SPF in my makeup. I don’t need to wear sunscreen.

False. While Patel says that sunscreen in makeup counts, it usually doesn’t provide the recommended SPF levels.

“It's typically only 5 to 15 SPF, and we recommend 30,” she says.

Check that your makeup offers at least 30 SPF, and supplement with additional sunscreen as needed. Finally, don’t forget to apply sunscreen to other exposed areas of your body, and make sure you reapply sunscreen as directed throughout the day.

Myth 8: I only need sunscreen when it is sunny.

False. Sunburn and sun damage may be associated with hot, sunny weather, but they can also occur in cold, cloudy conditions.

“Even when it's cold, sun is getting through the clouds,” Patel says. 

While clouds filter some UVB rays, they don’t block UVA rays which are a risk factor for melanoma, she adds.

So even if it’s cloudy or cold, you need to apply your sunscreen the same way you would if it were a warm sunny day.

Myth 9: Sunscreen doesn’t expire.

False. “You cannot rely on expired sunscreen,” Patel says. “Nothing bad is going to happen if you use an expired one in terms of increased toxicity. It just won't work.”

It is also important to store sunscreen properly. Specific storage instructions can be found in the product’s ‘Drug Facts’ section.

For example, if you store your sunscreen in a hot car or in direct sunlight, Patel says the product could degrade earlier than its expiration date.

"You have to look at the storage recommendations. Sunscreen will only last until the expiration date if you keep it within those temperature ranges," she says. "If you go outside of those temperature ranges, the molecules that are protecting your skin will degrade faster.”

Request an appointment at MD Anderson online or call 1-877-632-6789.

Almost everyone has at least one mole, and you may already regularly check your moles for signs of change.

That’s a good idea since a changing mole can mean that something has gone wrong in the cells and a cancer is forming.

So, does that mean that moles are cancerous? Or that you will get skin cancer if you have moles?

We talked to Saira George, M.D., a dermatologist at MD Anderson in Sugar Land, to find out.

What are moles?

Moles are clusters of melanocytes. These are the cells in our skin that give it color. These melanocytes are normally spread out between other skin cells. Their job is to transfer pigment, called melanin, to neighboring cells to help protect them from ultraviolet damage. When melanocytes grow as a cluster or group instead of spreading out, we call it a mole. It’s not clear exactly how or why our skin forms moles, but we think genetics and sun exposure may play a role.

Are moles cancerous?

Moles are not cancerous or dangerous. They are simply a group of normal melanocytes. But if their DNA gets damaged, it can cause them to turn cancerous. These cancerous growths of melanocytes are called melanoma. When the cancer cells in melanoma divide, they form a disorganized group or cluster that looks like a new or changing mole.

How do you tell the difference between normal moles and melanomas?

Moles usually form before you reach age 40, and they look somewhat similar. They are slow growing and don’t change quickly. The cancer cells in melanoma divide and grow abnormally, so a melanoma often looks like an “ugly duckling” mole. It will likely look different from any other brown spots on your skin, it may be new, and it may continue to change over time.

You can examine your moles using the ABCDEs guide for melanoma.