Soaking Up the Sun - The Ultra Violet ABC's

Just as smoking leads to lung disease, we all know heavy exposure to the sun can lead to skin cancer. Sunscreens have come a long way towards helping to protect us, but questions and misconceptions still exist.

Let's take a look at the different types of ultraviolet radiation that come from the sun, and why we need to protect ourselves in the first place. There are three types, referred to as UVA, UVB, and UVC. We generally don't hear about UVC, as it is totally absorbed by the atmosphere, so lets look at the first two. UVA and UVB are differentiated by their wavelengths, and how deeply they penetrate into the skin. Clinical studies have shown that UVA radiation, with its longer wavelengths, penetrates deeper, causing damage to the elastic fibers and collagen of the skin. This causes accelerated aging, resulting in wrinkles and leathery appearance of the skin. UVA also poses a greater risk in the development in skin cancer. UVB rays are shorter, and are what cause sunburn.

Traditionally, sunscreens have protected us only from UVB radiation. With the dangers of UVA radiation now better known, we want a sunscreen that protects from both, known as "broad spectrum" protection. How can we tell the kind of protection we are getting from the product label?

Sun Protection Factor (SPF) measures our level of protection. Contrary to popular belief, an SPF of 30 does not protect you twice as much as an SPF of 15, and it only measures UVB protection. There is not yet a standard for measuring UVA. So if you have a high SPF rating, but no UVA protection, you are not as safe as you think. SPF is actually a ratio of the time it takes to burn with protection on in relation to time to burn without it. For example, if it takes you 20 minutes to burn without protection, using an SPF 15 sunscreen theoretically prevents you from burning 15 times longer, or about 5 hours. A sunscreen of SPF 15 blocks 93% of UVB radiation, SPF 30 blocks 96%, and SPF 60 blocks 98%.

There are two distinct ways sunscreens protect us, by either absorbing and/or reflecting UV rays. Chemical sunscreens such as octyl-methoxycinnamate and oxybenzone absorb radiation. These chemicals are common allergens and skin irritants. Studies are also showing other health risks associated with chemical sunscreens, and they are beginning to accumulate in our water supply. Zinc oxide and titanium dioxide are minerals that reflect radiation and provide a chemical-free option for sunscreens. Several other natural ingredients also provide some level of sun protection, such as vitamins C and E, green tea, milk thistle, shea butter, jojoba oil, and PABA, a B vitamin.

There is yet another concern of sunscreen use. The very important vitamin D is created in the skin by UV absorption. Blocking out all radiation will therefore cause a reduction in vitamin D production, which has been linked to a wide range of health concerns such as inadequate calcium absorption, bone diseases, and cancers.

Choosing a sunscreen means more than getting the highest SPF, and involves some compromises. I hope you are now able to make a more informed choice on which products to buy. Yet again, knowledge is power. Have a great summer in the outdoors, and try not to get burned.