Did you know that the FDA regulates sunscreens like they do medications? It’s true! The FDA takes the position that sunscreens claim to do something that has a health benefit: they help prevent sunburn and decrease the risk of skin cancer and early skin aging. In this sense they are like a drug, so the FDA regulates sunscreens too. Sunscreens sold in Europe and other countries are regulated as cosmetics, not drugs, and are subject to different marketing requirements. If you purchase sunscreen abroad, check the label. What you are buying there may be very different than what you’d be getting here.
UVB and SPF
The sunscreen term most people know is SPF, which stands for sun protection factor. SPF is a measure of protection against ultraviolet B (UVB) radiation from the sun. UVB damages the skin’s more superficial layers, causing sunburn, and contributes to the development of skin cancer. SPF gives you an indication of how well a sunscreen will protect you from getting a sunburn. A sunscreen with SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97%, and SPF 50 blocks 98%. Think of it this way: imagine a child’s diagram of the sun: a ball surrounded by spikes, or rays. Suppose there are 100 of those rays. SPF 15 blocks 93 of those rays from reaching your skin, SPF 30 blocks 97, and SPF 50 blocks 98. UVB is also most intense between 10 am and 4 pm. That’s why we apply sunscreen more during those hours.
UVA
Ultraviolet A (UVA) accounts for 95% of the sun’s ultraviolet radiation that reaches earth. Unlike UVB, UVA is not blocked at all by the ozone, or by clouds, or even by windows. It goes right through all of them. UVA is present with equal intensity during all daylight hours, year round, not just from 10 am to 4 pm. It penetrates more deeply into the skin than UVB, damaging cells called keratinocytes in the deeper layer (the basal layer). Basal cells and squamous cells are specific types of keratinocytes. The most common skin cancers, basal cell carcinoma and squamous cell carcinoma, may be initiated by this deep penetration of UVA. UVA is also the dominant tanning ray. Tanning booths emit primarily UVA, and sometimes the doses are as much as 12 times that of the sun. You’ve got to really want that tan to take that kind of risk!
Check the Label
Sunscreen ingredients and potential toxicities
Currently there are 16 active ingredients marketed by companies in their various sunscreens. Of these 16, only two (two!!) – zinc oxide and titanium dioxide – are recognized as generally safe and effective by the FDA. The other 14? Not so much. There are questions about the safety of some of the other more common active ingredients. There is evidence that at least some sunscreen active ingredients may be absorbed through the skin and enter the body. Oxybenzone, for instance, may act as a hormone-disrupting agent. Octyl methoxycinnamate may have damaging effects on nerves. Vitamin A and its derivatives, retinol and retinyl palmitate, have been linked to an increased risk of skin cancer by increasing the speed at which malignant cells develop and spread. Because of these types of findings the FDA is asking sunscreen manufacturers to provide studies that prove their active ingredients are actually safe. The SkinCeuticals products shown above contain both titanium dioxide and zinc oxide but none of the other 14 ingredients.
Best protection from the sun
Other than staying out of the sun, the best protection may be clothing made specifically to protect against ultraviolet radiation. Clothing manufacturers use a rating system called UPF (ultraviolet protection factor). UPF is a measure of a fabric’s effectiveness against both UVA and UVB radiation. A UPF rating of 20 is good, 30 is very good, and 40 is excellent. Look for wide-brim hats, shirts, and pants with UPF at least 20. Sunglasses are important too. Your pupil controls how much light gets into your eye. When you wear darkened lenses, the pupil opens more to let in more light. If your sunglasses aren’t rated to block UV rays, you might be letting too much into your eyes. This can cause cataracts, damage the retina, and even cause tissue to grow over your eyeball. Be sure to buy sunglasses that block 100% of UVA and UVB rays. Nothing less will do.
For good protection against ultraviolet radiation, wear clothing with a UPF of at least 20, sunglasses that block UVA and UVB rays, and use sunscreens with SPF 30-50 that contain zinc or titanium dioxide and and say “broad spectrum” on the label. Don’t get burned!
