By Jennifer Linder, MD
Dr. Linder is a dermatologist and Mohs surgeon in private practice in Scottsdale, AZ, and a clinical instructor at UCSF Dept. of Dermatology.
Published in the Winter 2008 Edition of Sun & Skin News
Q. “I’m a melanoma survivor. The more I learn about sunscreens, the more confused I become. I’ve seen graphs of ultraviolet A and B (UVA and UVB) light ranges, showing which sunscreen ingredients work best to protect against the different ranges. I’m now using five different bottles of sunscreen to capture all the ingredients possible, spending a lot of money and driving myself nuts trying to figure all this out. Is it possible to find one sunscreen that will give me complete protection?”
A. I am glad to see you are making every effort to insure your health by protecting yourself from the full spectrum of UV rays. It is possible to obtain adequate protection using just one sunscreen. The key is to understand what to look for on package labels.
For any sunscreen product to provide adequate protection, it must be broad spectrum, meaning it protects against both UVA and UVB radiation, which both play a part in skin cancer and sun damage. Unfortunately, until Summer 2012, when the new FDA sunscreen labeling regulations go into effect, the phrases “broad spectrum” and “UVA protection” have no official meaning and can be used if the product covers even a small part of the UVA spectrum, which ranges from 320 nm (nanometers, or billionths of a meter) to 400 nm. You have to turn the bottle over to look at the active ingredient list. Some combination of the following five sunscreen ingredients must be included: avobenzone, titanium dioxide, ecamsule (Mexoryl™), oxybenzone, and zinc oxide.Learn about the new FDA sunscreen labeling regulations and what they mean for you.
Luckily, multiple agents protect the skin against UVB rays. These include, but are not limited to, homosalate, octinoxate, octisalate, and octocrylene, as well as the aforementioned oxybenzone. It is the combination of UVA and UVB protection as well as patient compliance that determines how well a product will work.
In addition to sunscreen agents, consider using a product that contains support ingredients to further shield the skin and the product’s active ingredients from environmental offenders and oxidation. Antioxidants and MMPi agents such as vitamins A, C, and E, omega-3 fatty acids, and soy and green tea derivatives, may provide the skin cells with some additional protection, although more research is needed. Antioxidants are believed to destroy free radicals, highly reactive compounds produced during metabolism that are believed to cause cellular damage in the skin, while MMPis are matrix metalloproteinase inhibitors, chemicals that hinder skin aging enzymes.
Even a sunscreen with broad spectrum ingredients and antioxidants must be applied correctly. At least one ounce (a shot glass full) of sunscreen should be used, and the same amount reapplied after two hours outdoors or immediately after swimming or sweating heavily. Applying more than one SPF product to your skin will not necessarily raise the SPF number; you will receive only the amount of protection provided by the highest SPF product applied. In my opinion, extremely high SPF ratings are deceiving, as SPF protection does not increase proportionally. For instance, SPF 30 sunscreen screens out 97 percent of UVB rays, while SPF 50 screens approximately 98 percent. No sunscreens block 100 percent of UV rays.
In addition to using sunscreen, please see The Skin Cancer Foundation’s Prevention Guidelines. Following these suggestions will keep you as safe as possible in your recovery.