Get the Facts: Sun Protection and Sunscreen

by Leslie P. Lawley, MD

We know everyone should use sunscreen, but why is it so important for kids? Good studies show that 25-80% of the sun damage leading to skin cancers and wrinkles occurs before age 18. Either end of the spectrum represents a significant amount of exposure and risk. Therefore developing and encouraging good sun safety habits early in life is important. A recent study in Colorado linked sun exposure in water areas (where reflection is also high) to the number of moles on children. The overall number of moles is a risk factor for developing melanoma later in life.

Choosing the right sunscreen

The sun protection factor (SPF) indicates the strength of the sunscreen against UVB rays. At this time there is not a scale for protection against UVA rays, however sunscreens are marked as having UVA coverage. The SPF is determined by testing 2mg of sunscreen per cm2 body surface area and exposure time to UVB rays to develop sun burn. It can be translated to the amount of time you can stay in the sun with less chance of sunburn. For example, if it only takes 10 min of sun exposure for you to start burning, then a sunscreen with SPF 30 affords you 300 min of time without burning. An SPF 60 would then give you 600 min.

The important point to remember when determining SPF is that you have to apply the correct amount of sunscreen in order to gain the effect: 2-3 tablespoons or 1 oz covers an adult therefore 1-2 tablespoons for each application on a child. In addition, over time sunscreen will lose effectiveness and wear off due to sweat, water exposure, and rubbing so you will not actually gain 300min from an SPF 30 sunscreen. That is why it is recommended to reapply sunscreen every 2 hours and after swimming. It is best to apply the sunscreen 30 min prior to going outside. Limiting sun exposure between 10am and 4pm when the sun is strongest is helpful too.

Are the protective shirts and swim gear as effective as sunscreen?

Yes. Sun protective clothing is marked with a UPF (Ultraviolet Protection Factor) instead of SPF. These fabrics are engineered to protect the skin from the damaging UV by absorbing the rays. Many sun protective clothes and hats are UPF 50 meaning that only 1/50th (or 2%) of the UV rays actually pass through the clothing to your skin.

There are many companies selling such clothing so I recommend researching the manufacturer to ensure a quality product. Note that wearing a regular white T-shirt, especially when swimming, does not provide good protection from the sun (ave UPF 7). In addition there is a laundry additive available that infuses a sunscreen into your clothing.

When does that sun protective clothing lose their effectiveness?

Great question. The regular washing and wear and tear of this clothing decreases the protective factor but it is not clear how long they last. Again research in the quality of the product is important to ensure buying an article of clothing that will last longer. The laundry additive lasts for 20 washings.

How long does sunscreen last-we have bottles sitting on our shelves from last year. Still work?

All sunscreens should be marked with a date of expiration. Beyond this date the actual efficacy of the sunscreen is in question. If you are using the correct amount of sunscreen with each application (see #2) then a bottle should not last from one summer to the next. Most sources suggest that if a date of expiration is not on the bottle to discard it after 2 years.

I’ve heard that if you have a bad sunburn your chances increase to get melanoma later in life. Can you explain?

Studies have identified certain risk factors for developing melanoma later in life. One of these is a history of blistering sunburn: one blistering sunburn can double your chance of developing melanoma. Additional risk factors known at this time are family history of melanoma, a large number of moles and “funny looking” moles (called dysplastic moles) , family history of dysplastic moles ,fair skin and red hair, personal history of melanoma, and an compromised immune system.

Kids with special needs often are on a lot of medicine; can that make them more susceptible to skin cancer? Or can different medicines make sunscreen ineffective?

Sunscreens would not be directly less effective due to systemic medications, however, some medications make patients more sensitive to UV rays of the sun. Therefore if your child is taking a medication that makes him/her more sensitive to sunlight then the sunscreen used may need to be a higher SPF to get the same effectiveness. Some examples of medications that may cause sun sensitivity include, but are not limited to: doxycycline, methotrexate, ciprofloxacin, sulfa medications, alprazolam, griseofulvin, glipizide, and vorizonazole. Speak with your child’s physician regarding your child’s medications to understand if there is increased sensitivity to the sun reported with their specific treatments.

The Skin Cancer Foundation has a very informative website for further information: www.skincancer.org.

Leslie P. Lawley, MD is an Assistant Professor of Dermatology at the Emory University School of Medicine