Memorial Hospital - June 07, 2018
by Joshua Patton, Doctor of Osteopathic Medicine Candidate 2019, and Megan Barber, Doctor of Pharmacy Candidate 2019

Let's play a game called fact or fiction: 1) A base tan is a “natural sunscreen”, 2) If you do not get sunburns you will not get cancer, 3) Tanning is an amazing source of vitamin D. If you said all of those statements were fiction then you are correct! Many people dream of having the perfect tan, but in reality we are causing more harm than good. Too much sun has been linked with not only skin cancers, but also premature aging of the skin.

Sunlight is made up of two types of ultraviolet radiation; UVA and UVB. The UVA rays are stronger and therefore penetrate deeper into the skin than their counterpart UVB rays. Additionally, UVA rays are to blame for the premature skin aging that is associated with repeated, unprotected sun exposure. The amount of UVA rays we are exposed to generally remains constant, whereas UVB exposure increases during summer months. On the other hand, UVB rays are what cause our skin to “tan” and “burn.” Although each causes its own damage in one way, they are both linked with skin cancer. For this reason, we should apply sunscreen to all exposed skin every time we leave the house.

Surveys from The Skin Cancer Foundation show one of five Americans will be diagnosed with skin cancer at one point in his or her life. The three main types of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and malignant melanoma (MM). In 2009, the International Agency for Research on Cancer confirmed that ultraviolet radiation is a direct cause of all three skin cancers. Studies show in 2015 over 5 million people in the US were treated for skin cancers. Even more alarming is that melanoma rates rose over 200% from 1973 to 2011. BCC is the most common skin cancer in humans and fortunately has the least chance to metastasize. SCC is the next most common and has a very small chance of spreading. MM, however, is the worst of the three and has the highest chance of metastasizing. Most importantly, the use of sunscreen can decrease the incidence of all three.

What we refer to as “sunscreen” actually falls into the broad category of photoprotective agents. The two main photoprotective agents are sunblock, which is opaque and “blocks” the sun; and sunscreen, which is translucent and must be reapplied more frequently. Sunblocks use physical properties to reflect, scatter, and block the sun’s rays and were designed to protect against UVB rays. The two main ingredients to look for in a sunblock are titanium dioxide and zinc oxide. Both act by reflecting UV rays and do not degrade in the sun. For this reason, they are a good first choice for use in children. Alternatively, sunscreens use chemical properties to absorb UVA rays from the sun before they can damage the deep skin layers. Avobenzone is the best known chemical in sunscreens, and is the most widely used organic ingredient. Octisalate is another ingredient present in many sunscreens, and helps stabilize Avobenzone. When picking out a sun photoprotective agent, ingredients you want to avoid are para-aminobenzoic acid (PABA), oxybenzone, homosalate, and octinoxate. PABA can be irritating to people with sensitive skin. Endometriosis and allergic reactions have been linked with oxybenzone. Homosalate and octinoxate have been shown to alter hormone levels and homosalate may even have harmful break-down products. The most common adverse event associated with photoprotective agents is contact dermatitis, which is an inflammatory response to a substance contacting the skin. If your skin gets red and irritated in areas where you applied, you may have a minor allergy to an ingredient in that product and should switch to another. Most dermatologists will recommend using a sunblock with titanium dioxide or zinc oxide for those with sensitive skin as these two ingredients penetrate the skin much less than those in sunscreens. People with allergy-prone skin, acne, or rosacea should avoid products with fragrances as these may exacerbate the preexisting conditions. Furthermore, those with acne should avoid photoprotective agents with alcohol and those that are in the cream form. If you suffer from dry skin, be sure to choose a sunscreen with moisturizing ingredients such as lanolin, oils, or dimethicone. Darker skinned individuals may face an issue when applying sunblock because of its difficulty to completely rub in. However, newer zinc oxide and titanium dioxide containing products are micronized which allows them to “disappear” into the skin. Fortunately, most photoprotective agents manufactured now are “broad spectrum.” This means they protect against both UVA and UVB.

As you may have noticed sunscreens are measured in SPF; but what does that mean? In general, the number after SPF is how much longer you can spend in the sun compared to if you were not wearing any sunscreen. The most important thing to take from this is the higher the number, the better protection you are providing your skin. With that being said, many physicians and scientists will tell you anything above SPF 50 truly doesn't provide much of a difference. For example, SPF 30 blocks out 97 percent of UV radiation and SPF 50 blocks out 98 percent. For normal everyday sun exposure such as walking to and from your car, SPF 15 is sufficient. If you plan on spending extended time in the sun, an agent with SPF 30 or greater is advised for extra protection. The SPF value can be altered by overheating so be sure to store you sunscreen in the shade.

Another label you may see on the bottle is “waterproof” or “sweatproof.” This is misleading, as no product is truly water or sweatproof and any product that claims to be water resistant must clearly indicate the duration of effectiveness. Even though a product may be water or sweat resistant, it is still recommended to reapply every 2 hours or after toweling off. The initial application of sunscreen should be at least 30 minutes before sun exposure. The two biggest reasons sunscreens fail is under application and failure to reapply.

Although we now know what ingredients to look for, recent studies have shown that we lack in both usage and proper application technique of sun protective agents. Some studies even show we only apply one quarter of the amount we should be. A normal sized adult should use one ounce (capacity of a shot glass) of sunscreen each application to cover from head to toe. A 2017 study on sunscreen application showed females are better at applying sunscreen than males and that both genders were better at applying sunscreen to the front of their body compared to the back. An average of eleven percent of the body was not adequately covered by sunscreen. The most commonly uncovered parts were feet, upper back, bikini area, and hands. The biggest take home from this study was that further public education regarding proper sunscreen use is needed.

In conclusion, the best advice to avoid premature skin aging and the risk of skin cancer is to , avoid direct sun exposure between 10:00 a.m. and 3:00 p.m., reapply sunscreen at least every two hours, spend most of your time in the shade while outside, and wear a wide-brimmed hat and long sleeves when in the sun. The next time you go to the store, remember the best sunscreen is whichever one you will consistently use.

Q: Zinc based sunblocks are too thick and appear white on my face, is there any way to prevent this?

A: Titanium dioxide and zinc oxide can be produced in a micronized form that will not appear thick on your face. Look at the ingredients list for micronized zinc oxide when you purchase your next sunblock.

Q: How frequently do I need to reapply?

A: It is recommended to reapply every 2 hours or after toweling off.

Q: What populations are more prone to develop skin cancers?

A: Dialysis and organ transplant patients, fair-skinned individuals, people with repeated blistering sunburns.

Q: What kind of sunscreen should I use if I have acne or oily skin?

A: A spray or gel-based sunscreen is recommended for those with oily skin or acne.

Q: When is the worst time to be in the sun?

A: From 10:00am to 3:00pm the sun is capable of causing the most skin damage.

Q: Are tanning beds safer?

A: No, tanning bed lights emit UV light as well that damages our skin.

Q: Does sunscreen expire?

A: Yes, most sunscreens will have an expiration date. However, if no date is found you should not use the product more than 3 years after purchase.