Screen your skin from the sun

With the dog days of summer in front of us, we need to focus on keeping our largest bodily organ, the skin, safe.

Sunlight plays an integral role in Vitamin D synthesis and improves our mood. But it can also cause permanent damage to our skin.

Over the years research has shown that sunscreens have protective benefits against the harmful ultraviolet (UV) rays that cause precancerous skin lesions and skin cancer (1-3). An Australian trial found that the regular use of sunscreen also reduces the incidence of malignant melanoma, the deadliest of skin cancers (4).

Sunscreen may also prevent skin changes such as darkening and wrinkle development, called photodamage or photoaging (5).

UVB represents 5% of the UV light that reaches the earth and is the most active type. It causes sunburn, aging of the skin and skin cancer.

UVA has subtypes; UVA2 carries the same detrimental effects as UVB on the skin (2).

The broad-spectrum sunscreens are recommended and have protection against both UVA and UVB.

All individuals, regardless of skin type (fair-skinned to dark complexion), can sustain the effects of UV radiation and can benefit from sunscreen use. However, lighter-skinned persons likely reap more of the benefit. These are people who are more susceptible to sunburns and aging effects of the sun.

It is important to understand sun protection factor, or SPF. This is a measurement of the sunburn-producing UV rays that reach the skin. For example, an SPF of 15 means that 1/15th of the bad radiation will reach the skin. A person can calculate the effectiveness of his or her sunscreen "by multiplying the SPF factor by the length of time it takes for him or her to suffer a burn without sunscreen" (6).

So, if someone gets burned in 20 minutes without the sunscreen applied, then he would avoid the sunburn for 300 minutes if an SPF 15 sunscreen was applied.

This also means that there is not a direct relationship between SPF and protection; SPF 30 is not twice as protective as SPF 15.

That being said, sunscreen products with SPF 30 or more are recommended for those participating in outdoor work, sports, or other recreational activities.

It is recommended that people, especially the fair-skinned type, routinely wear SPF 30 and higher when outdoors and in the sun.

For daily use, SPF 15 is typically sufficient to protect against sun exposure associated with a work commute, walking to and from the car, and other short-term exposures.

Broad spectrum sunscreens are preferred over those only protecting against UVB, since both UVB and UVA are detrimental.

The American Academy of Pediatrics recommends avoiding the use of sunscreen products in infants younger than six months. However, when adequate clothing and shade are not available, a minimal amount of sunscreen with at least SPF 15 can be applied to small areas, such as the infant's face and the back of the hands.

The proper application of sunscreen is imperative to reaping its benefit. It must be applied liberally and repeatedly to all sun-exposed body parts. A common place I find skin cancer in the clinic is the top of the head in balding men, and on the ears, no doubt due to neglect of those areas with sunscreen.

Most people apply too scant an amount of sunscreen to their skin and as such, do not get the full SPF value on the bottle. It is because of this that it is recommended that one choose SPF 30 or higher to
compensate.

Timing is also very important. Sunscreen should be applied 15-30 minutes before the planned sun exposure to allow the protective layer to take hold. This means that it should be spread on before leaving the house for the beach.

Furthermore, it must be reapplied every two hours.

Sunscreens that claim they are "water-resistant" still need reapplied after each water exposure as they are still washed off with swimming and other water activities.

One word further about Vitamin D. Vitamin D is an essential nutrient that plays a large role in calcium homeostasis and bone health. Since sun exposure is necessary for the synthesis of this vitamin in the
skin, there has been concern that photoprotective measures can yield a vitamin deficiency. Hoewever, there has been no evidence from randomized trials that sunscreen use significantly interferes with vitamin D production in real life (7).

In a patient who needs strict sun-avoidance, oral supplementation of the vitamin is a safe and effective alternative.

The Skin Cancer Foundation in the United States has developed a list of products, including cosmetics, clothes, and laundry additives, that can provide sun protection. Check out http://www.skincancer.org/prevention/seal-of-recommendation.

Several daily moisturizers and lotions have SPF in them already, so a simple way to remember to wear your sunblock is to apply your daily SPF-infused lotion after your daily shower.

My personal dermatologist informed me to wear SPF 30 daily on my face, ears, and neck - advice I comply with year round - saying, "You'll thank me in 20 years."

Michele Brannan is a certified Physician Assistant of Internal Medicine and has been in practice in the Riverbend area for over 10 years.

The health information provided herein is not intended to replace the advice or discussion with a healthcare provider and is for educational purposes only. Before making any decisions regarding your health, speak with your healthcare provider. 

REFERENCES:
1.Darlington S, Williams G, Neale R, et al. A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses. Arch Dermatol 2003; 139:451.
2.Green A, Williams G, Neale R, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. Lancet 1999; 354:723.
3.van der Pols JC, Williams GM, Pandeya N, et al. Prolonged prevention of squamous cell carcinoma of the skin by regular sunscreen use. Cancer Epidemiol Biomarkers Prev 2006; 15:2546.
4.Hackenberg S, Kleinsasser N. Dermal toxicity of ZnO nanoparticles: a worrying feature of sunscreen? Nanomedicine (Lond) 2012; 7:461.
5. Hughes MC, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med 2013; 158:781.
6. Jump up to: a b Sunblock. UCSF. School of Medicine. Dept of Dermatology.
7. Diehl JW, Chiu MW. Effects of ambient sunlight and photoprotection on vitamin D status. Dermatol Ther 2010; 23:48.

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