A while back we ran a Health Matters column on Wearing Sunscreen Under a Jersey. Click the link to read that column. It provides advice on combining sunscreen with whatever protection your jersey might already afford. Hint: It may not be much.
It’s already been sizzling for the past few weeks in the Southeast, and summer temps will eventually rise across the country. As a service to readers as we enter “sun season” again, we’re running the following column taking a look at the basics of sunscreen: what’s in it, how it works, what do the letters and numbers mean, etc.
What’s in it, And How it Works
Sunscreen works in one of two ways: It either blends into the skin and absorbs UVA and UVB rays (more on those below), or it sits on top of the skin and reflects damaging rays.
The types that blend into the skin use chemical blockers such as avobenzone and Mexoryl, which can degrade in the heat and through sweat. They must be reapplied regularly if you’re exposed for an extended period of time.
The other type, the physical blockers, that sit on the skin include zinc oxide (made famous on the noses of lifeguards) and titanium dioxide. While they may work better for some folks with sensitive skin, they’re obviously not ideal for cyclists.
What Do the Letters and Numbers Mean?
UVB rays are the ones that cause sunburns and skin cancer. The sun-protection factor (SPF) number provides an indication of how long the sunscreen formula resists those harmful UVB rays. For example, if your skin typically would start to burn after 10 minutes of exposure, a liberal coat of SPF 30 will multiply that time by 30, giving you roughly 300 minutes of protection against UVB rays.
Again, though, environmental factors (swimming, sweating, heat, etc.) degrade many sunscreens, decreasing the SPF and requiring regular reapplication to maintain protection. Some sunscreen is water-resistant, but none is waterproof. If it is labeled “water-resistant,” it is supposed to remain effective for 40 to 80 minutes of swimming or sweating (the label should state the claimed time).
Also, the SPF number does not describe protection against UVA rays, those responsible for prematurely aging the skin; UVA rays can also cause cancer. So, to provide protection against both UVB and UVA rays, you need to use a sunscreen labeled “broad spectrum” protection.
How Long Does a Tube or Bottle Last?
Just as environmental factors degrade sunscreen on your body, the product in the tube or bottle can likewise be degraded if left in the heat or direct sun. Keep an eye on the color and consistency of the product; if it changes, toss it. And consider doing the same with whatever’s left if the bottle at the end of summer.
FDA Labeling Regulations
As the scientific testing of sunscreens has become more advanced, the U.S. Food and Drug Administration (FDA) rolled out new sunscreen labeling regulations to both simplify and clarify the claims and labels used by manufacturers.
Under the regulations, sunscreen products that protect against all types of sun-induced skin damage are labeled “Broad Spectrum” and “SPF 15” (or higher) on the front.
The labeling also tells consumers on the back of the product that sunscreens labeled as both “Broad Spectrum” and “SPF 15” (or higher) not only protect against sunburn, but, if used as directed with other sun protection measures, can reduce the risk of skin cancer and early skin aging.
The FDA regs announced in 2011 included these additional labeling provisions:
- Sunscreen products that are not broad spectrum or that are broad spectrum with SPF values from 2 to14 will be labeled with a warning that reads: “Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging.”
- Water resistance claims on the product’s front label must tell how much time a user can expect to get the declared SPF level of protection while swimming or sweating, based on standard testing. Two times will be permitted on labels: 40 minutes or 80 minutes.
- Manufacturers cannot make claims that sunscreens are “waterproof” or “sweatproof” or identify their products as “sunblocks.”
- Also, sunscreens cannot claim protection immediately on application (for example, “instant protection”) or protection for more than two hours without reapplication, unless they submit data and get approval from FDA.
Finally, the FDA created the following, which you’ll find nearly verbatim on the back labels of your sunscreen container:
Spending time in the sun increases a person’s risk of skin cancer and early skin aging. To reduce these risks, consumers should regularly use a Broad Spectrum sunscreen with an SPF value of 15 or higher in combination with other protective measures such as:
- Limiting time in the sun, especially between the hours of 10 AM and 2 PM when the sun’s rays are the strongest. [Tip! Most online forecasts have a UV Index listing. You can see that mid-day listings typically reach 10, the highest rating indicating the strongest UV rays.]
- Wearing clothing to cover skin exposed to the sun (long-sleeved shirts, pants, sunglasses, and broad-brimmed hats) when possible.
- Using a water resistant sunscreen if swimming or sweating.
- Reapplying sunscreen, even if it is labeled as water resistant, at least every 2 hours. (Water-resistant sunscreens should be reapplied more often after swimming or sweating, according to the directions on the label.)