Summer is officially here! It's important to protect our skin now that we're spending more time in the sun. Many of us turn to sunscreen, but do you know how it works and are there concerns about certain chemicals in it?

Here are some questions that you may have about sunscreen:

Why use sunscreen?

The sun's ultraviolet A (long-wave) and ultraviolet B (shortwave) rays can both cause skin damage to our skin. Sunburn is primarily caused by UVB from the sun, but both UVA and UVB can cause skin cancer, sunburn, and accelerate skin aging. Skin cancer is one of the most common cancers and certain types may have a high mortality rate, depending on the type and staging of the disease. Therefore, the use of the proper amount and application schedules of sunscreen are critical for preventing skin cancer.

What types of sunscreen are there for me to choose from for my family?

There are two main types of sunscreens – physical and chemical. Physical sunscreens are either zinc oxide or titanium dioxide. Recent advances in nanoparticulates has allowed for the production of nano-based sunscreens. These are most likely safe, but there is still much research being done on the adverse effects of nanoparticulates, or lack thereof.

Chemical sunscreens include active ingredients that absorb high energy sunlight and release them out as low energy rays. These are mostly organic compounds and there are many that have been approved by the U.S. Food and Drug Administration for use in sunscreens, including avobenzone, oxybenzone, octyl salicylate, and many others. In some cases, the chemical structure is altered during protection, but this does not necessarily mean there are potential side effects. In addition, sunscreens can also contain inactive ingredients that make up the vehicle which carries the active ingredient. These inactive ingredients may also function as preservatives or stabilizers.

What does SPF mean?

Sunscreens are rated based on SPF levels. SPF stands for sun protection factor. The higher the SPF, the more the protection. There is a mathematical formula to calculate SPF, but in plain English, SPF is essentially calculated by dividing the amount of light needed to cause redness in sunscreen protected skin by the amount of light needed to cause the same amount of redness in unprotected skin. An SPF of 15 filters 92 percent of UVB. It will allow a person to stay in the sun longer.

However, because no sunscreen is perfect and because there are factors that limit their effectiveness, the FDA has regulated what can go on a label. For example, no sunscreen is truly waterproof, so labels cannot claim to be effective for more than 2 hours. Sunscreens can only be labeled as broad spectrum if it blocks both UVA and UVB radiation. The effectiveness of sunscreens over SPF 50 is unknown, so the maximum protection factor that can be stated on a label is SPF 50+.

Can I get a skin rash from wearing sunscreen?

Sunscreens are generally safe, but they can cause a rash in susceptible individuals. The most common skin rashes resulting from sunscreens are irritant contact dermatitis and allergic contact dermatitis. These are usually delayed reactions, so they may not occur immediately after application. Some of the components of sunscreens that may cause such a problem include formaldehyde, benzophenone, or lanolin.

Many other components that function as fragrances may also cause a rash. If a particular sunscreen does cause this type of problem, you can ask for a referral to an allergist or dermatologist who can then perform an allergy patch test to identify the culprit ingredient. You should try to purchase an alternative sunscreen which does not have that particular component. A variant is photoallergic contact dermatitis, in which case the offending substance reacts with sunlight and becomes a different molecule capable of inducing a contact dermatitis.

What are some good resources to learn more sunscreen safety?

Some of you have probably seen information from the Environmental Working Group about choosing a safe sunscreen, but we should be wary of such information.The EWG is a research and advocacy group that tries to change public policy and industry standards, largely through consumer-friendly tools and databases similar to the sunscreen report, as this article discusses. These tools may or may not be reliable sources of information.

The Centers for Disease Control and Prevention, National Institutes of Health, or the FDA have reliable information regarding health products and their side effects. Here is more information from the American Academy of Pediatrics on choosing a sunscreen for your child.

The bottom line is, sunscreens are extremely important in preventing skin cancer and should be used when outdoors in all individuals. Occasionally, some people can develop a reaction to sunscreens and an alternative should be sought.

Have a question for the Healthy Kids panel? Ask it here. Read more from the Healthy Kids blog »