May 8, 2010

Sunscreens and Their Use

On August 3, 2009, I wrote about sunscreens – safe or not. While there are many that are unsafe, you still need to use them when in the sun and to protect yourself from sunburn and future potential skin cancers.

Sunscreens are chemical agents that help prevent the sun's ultraviolet (UV) radiation from reaching the skin. There are two types of ultraviolet radiation, UVA and UVB, and both damage the skin and increase your risk of skin cancer.

UVB is the chief culprit behind sunburn, while UVA rays, which penetrate the skin more deeply, are associated with wrinkling, sagging, and other effects of aging. They also encourage the carcinogenic effects of UVB rays, and are being seen as a cause of skin cancer on their own. Sunscreens vary in their ability to protect against UVA and UVB.


Many people don't like to use these zinc and titanium based sunscreens because they can be hard to use and they often leave a ghost-like residue. Others just want to avoid using these products. If you are among these people, see a list of the top non-mineral sunscreens.  For children above six months of age and for safe sunscreens - see this list.

SPF stands for sun protection factor.

There are some problems with the SPF model: First, no sunscreen, regardless of strength, can be expected to stay effective for more than two hours without reapplication. Second, "reddening" of the skin is a reaction to UVB rays alone, but does not tell you about what UVA damage you may be getting. Damage can be done without the red flag of sunburn being raised.

Who Should Use Sunscreen?

Anyone over the age of six months should use a sunscreen. Even those who work indoors are exposed to ultraviolet radiation for brief periods throughout the day. UVA is not blocked by most windows. Children under six months of age should not be exposed to the sun. Shade and protective clothing are the best ways to protect infants from the sun.

To ensure that you get the full SPF of a sunscreen, you need to apply 1 oz – about a shot glass full. Studies have found that most people apply only half to a quarter of that amount, which means the actual SPF they have on their body is lower than the required amount on the container. During a long day at the beach, one person should use around one half to one quarter of an 8 oz. bottle. Sunscreens should be applied 30 minutes before sun exposure to allow the ingredients to fully bind to the skin. Reapplication of sunscreen is just as important as putting it on in the first place, so reapply the same amount every two hours. Sunscreens should be reapplied immediately after swimming, toweling off, or sweating a great deal.

Sun exposure is the most preventable risk factor for all skin cancers, including melanoma. You can have fun in the sun and decrease your risk of skin cancer. Here's how to be sun aware:

Generously apply a water-resistant sunscreen with a Sun Protection Factor (SPF) of at least 30. That provides broad-spectrum protection from both ultraviolet A (UVA) and ultraviolet B (UVB) rays to all exposed skin. Reapply approximately every two hours, even on cloudy days, and after swimming or sweating. Look for the AAD SEAL on products that meet these criteria.

Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses, where possible.

Seek shade when appropriate, remembering that the sun's rays are strongest between 10 am. and 4 pm. Another guide to remember is “if your shadow is shorter than you are, seek shade”.

Protect children from sun exposure by playing in the shade, using protective clothing and applying sunscreen.

Use extra caution near water, snow, and sand because they reflect the damaging rays of the sun, which will increase your chance of sunburn.

Get vitamin D safely through a healthy diet that may include vitamin supplements. Don't rely on the sun. Wearing sunscreen can cause vitamin D deficiency.

Avoid tanning beds. Ultraviolet light from the sun and tanning beds can cause skin cancer and wrinkling. If you want to look like you've been in the sun, consider using a sunless self-tanning product; however, continue to use sunscreen with it.

Check your birthday suit on your birthday. If you notice anything changing, growing, or bleeding on your skin, see a dermatologist. Skin cancer is treatable when caught early.

Self-tanning lotions and sprays are a safe alternative to tanning. They contain dihydroxyacetone which interacts with proteins in the skin to produce an orange/tan color that does not wash off. However, the color of self-tanners only has an SPF of 4. This is not enough protection; therefore, sunscreen with a SPF of at least 15 must be used and reapplied every two hours.

Everyone needs sunscreen. More than 1 million cases of skin cancer are diagnosed in the United States every year. Studies have found an association between sunburns and enhanced risk for melanoma, the deadliest form of skin cancer. The Food and Drug Administration (FDA) and the American Academy of Dermatology (AAD) recognize six skin categories:

Skin Type             Sun History

I             Always burns easily, never tans, extremely sun-sensitive skin
II            Usually burns easily, tans minimally, very sun-sensitive skin
III           Sometimes burns, tans gradually to light brown, sun-sensitive skin
IV           Burns minimally, always tans to moderate brown, minimally sun-sensitive skin
V            Rarely burns, tans well, sun-insensitive skin
VI           Never burns, deeply pigmented, sun-insensitive skin

The American Academy of Dermatology recommends that, regardless of skin type, a broad-spectrum (protects against UVA and UVB rays), water-resistant sunscreen with a Sun Protection Factor (SPF) of at least 30 should be used year-round.

Added 5/12/10  The following article is worth reading about the five common sunscreen mistakes or maybe should be titled "read the instructions ......".