Sunscreen use—for prevention of skin cancer or for reducing the effects of skin aging?


Well-known member
Sunscreen use—for prevention of skin cancer or for reducing the effects of skin aging?

I have a mundane questions about sunscreen and the need for reapplication. Specifically: if I apply sunscreen in the morning before I go to work and only spend about 15 minutes total outside before getting to my building is my sunscreen no longer effective by the time I leave the office at 5 or 6? Is the expectation that I reapply before I leave work? Seems impossible for my face since I'm wearing makeup. I did look into a sunscreen mineral powder by Peter Thomas Roth, but if I'm spending $50 the brush shouldn't feel like I picked it up in a Walgreens kit.

So, why are we really using sunscreen—for cancer prevention or for decreasing the effects of aging? Well, likely the answer is a little bit of both. Melanoma is the most deadly form of skin cancer. Click here for more information on melanoma. “The best way to prevent melanoma related mortality is to not get this cancer in the first place, and we know that sunscreen use does work for melanoma prevention” (Guttman Krader, 2012, p. 63).

Studies performed on hairless mice have indicated a decrease in skin aging, but “is not matched by human evidence. A trial in 35 patients with a history of skin cancer randomly assigned to sunscreen or placebo for 2 years showed no significant difference in dermal elastosis with sunscreen use” (Williams, Baker, & Green, 2013, p. 781). However, in a study performed by Williams, et al. it was demonstrated “that regular application of sunscreen by people younger than 55 years for 4.5 years significantly retarded aging of the skin” (Williams et al., 2013, p. 787). Whew—we got that one out of the way! Not to make light of the findings—I think it’s really important to have our information validated by tried and true research. If we just think that it helps, but have nothing to base our opinion on, then it is just that---an opinion.

Now to get to the question regarding the duration of protection a single application of sunscreen provides. That’s a little bit trickier. New FDA regulations will define for manufacturers what waterproof, broad spectrum, and SPF ratings mean in a concise manner, but the FDA will not require manufacturers to “tell consumers how long the sunscreen will last before the filters break down ("substantivity") and how cosmetically acceptable the formulation is” (Guttman Krader, 2012, p. 64).

Honestly, I do not see a single application of sunscreen providing more than a few hours of protection. According to what the manufacturers are required to report the longest a sunscreen provides protection in the presence of water is 80 minutes. Therefore, one can extrapolate that outside of the presence of water sunscreen would likely provide protection for a longer duration. It sounds to me that you are exposed to direct sunlight for only a short period of time and are very cognizant of whether or not you are over exposing yourself to the harmful effects of the sun. The most damaging part of the day is between 10am and 2 pm—likely you are being protected by the morning application of sunscreen during this time. UV exposure is significantly reduced after you leave work at 5 or 6pm.

We should also bear in mind that exposure to UV light (aka sunlight) is essential to the synthesis of Vitamin D by our body. As will all things in life—moderation must be applied. We all have different skin tones, familial history/predisposition, and environmental conditions—so consulting with your primary healthcare provider is helpful in determining what is right amount of sun exposure is for you. Any changes in current moles or formation of new moles should be evaluated immediately by your physician, nurse practitioner, or physician assistant.

***disclaimer—this is for informational purposes only and is not meant to replace or supersede the advice of your healthcare provider***
I have also attached the PDF files of the articles that are referenced for your reading pleasure.

Guttman Krader, C. (2012). Counseling consumers: New labeling requirements, recent literature provide w groundwork for educating patients about sunscreen use. Dermatology Times, 33(8), 63-64.

Williams, G. M., Baker, P., & Green, A. C. (2013). Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med, 158(11), 781-790. doi: 10.7326/0003-4819-158-11-201306040-00002




Well-known member
Thanks, Jessica. I do try to minimize my exposure to the sun - especially without sunscreen. I'm going to keep searching for one of those mineral sunscreens already loaded into a brush. Unfortunately the two that I've tried so far, Bare Minerals and Peter Thomas Roth, have incredibly rough brushes that I can't imagine touching to my face. Maybe I'll just have to find another powder/mineral sunscreen and carry along a brush in my purse.

Can anyone recommend a good, portable powder sunscreen?

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