Everything You Need to Know About Sunscreen
Posted April 7, 2011, 10:05 a.m.
Updated April 7, 2011, 2:55 p.m.
The rain appears to have stopped and the sun is shining so it is time to consider (or reconsider) protecting your face from the damage that sun exposure can cause. I have been seeing a lot of new patients for Sciton laser treatment of photoaging. What comes up over and over again in these consultations is that people are aware that sunscreen, particularly on the face must to protect skin. Everyone is aware that sun exposure increases the risk of skin cancer and causes wrinkling, sunspots and broken capillaries, all of which add years to our appearances. Rosacea is also worsened by the sun in people prone to this condition. Those coming to see me are quite diligent in using some sort of sun protection on a daily basis. The problem is, that most of them are using SPF alone as their guide for protection. And SPF is misleading. Here's why:
1. SPF rating system rates for UVB only. There is no rating system UVA. UVB causes tanning and burning, UVA causes the chromosomal damage that leads to photoaging and skin cancer. SPF rating does not tell you whether you have adequate, or indeed, any UVA protection.
2. SPF is a logorithmic scale. Skipping all the mathematical explanations, suffice it to say that an SPF of 15 blocks 95% of UVB radiation for the time specified, and SPF 45 blocks 97% of UVB for the same time. The added protection of SPF 45 over SPF 15 is 2% but the chemical concentrations required to achieve this may be up to 4 times that of SPF 15 products. Not only does this increase the price of the sunscreen, but higher concentrations of active chemicals increases the risk of the user developing irritation from its use. In my opinion, there is no need to use a product rated higher than SPF 15; protection is incremental above that and still may not guard against UVA at all.
3. Sunscreens are regulated by the FDA as cosmetics, not pharmaceuticals. This means that claims printed on the bottle do not have to be backed by scientific proof. You may be using a product that claims to be UVA, UVB protective, but the chemicals in these products providing UVA protection are photo unstable; withing 5 minutes of application and exposure to sunlight, they are no longer active. Unbelievable, right? Unfortunately true.
So, what to do? the answer is really simple: ZINC OXIDE. Now formulated to be cosmetically acceptable, micronized zinc oxide acts as a "physical block" reflecting light. It does not work by chemical reaction with your skin to prevent the absorption of UV radiation, and so, is completely stable. Titanium dioxide is another "physical block" but only zinc oxide protects against the full range of the UVA spectrum, titanium dioxide does not. So make sure your sunscreen, whatever brand you choose, has at least 5% zinc oxide or Z-cote, the registered trade name. Use it every day, even if you think you will not be outside at all, and you will protect yourself from both UVB and UVA radiation and help your skin stay healthy and great looking.