Beach Umbrellas Not Enough to Protect Against Sun.
As beach season approaches, a useful and somewhat counterintuitive new study published in JAMA Dermatology is worth keeping in mind.
To explore the effects of sun exposure on people using different forms of protection, the study randomized 80 subjects into two groups. One group was instructed to apply sunscreen every two hours while on the beach for 3.5 hours beginning at midday. The other group used UV-blocking beach umbrellas to protect them from the sun at the same time of day and for the same duration.
The sunscreen group, which utilized a very strong SPF-100 sunblock, fared better than the group seeking shade under beach umbrellas. One day after sun exposure, the participants were evaluated for sunburn by a clinician. The umbrella group had a total of 142 sunburned areas, as opposed to only 17 such areas in the sunscreen group.
Another way to frame this data is to compare the differences between the two groups as measured against their baseline level of sunburn. Compared with baseline, global sunburn scores increased significantly in 78% of the subjects in the umbrella group versus 25% in the sunscreen group.
While the study was relatively small, the differences in the outcomes between umbrella shading and strong sunscreen are certainly meaningful. It is worth noting here, as the authors do in the study, that even still, neither method completely prevented sunburn from all seven areas of exposure on the body that were examined after the day of sunbathing. And this study highlights what is known about UV exposure: shade works by physically shielding skin from direct harmful UV rays, but skin may still remain exposed to reflected and indirect UV rays. It remains a best practice to use a combination of sun screen protections to minimize risk of UV ray exposure, especially given the significant rise of skin cancers in recent years.
Sun exposure is one major way for humans to get sufficient vitamin D--our skin manufactures it when in contact with sunlight. Yet, as we explored in the previous issue, several leading endocrinologists have been arguing lately for a lowering of the currently accepted threshold level of 20, feeling that many clinicians are overscreening for and unnecessarily treating perceived vitamin D deficiency.
Over the past three decades, more people have had skin cancer than all other cancers combined. With statistics like this, it may be time to prioritize aggressive UV protection over the benefits of exposure on vitamin D production. For more info on identifying potentially cancerous skin irregularities, see "Check Yourself for Skin Cancer" in this issue.
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|Publication:||Running & FitNews|
|Date:||Mar 1, 2017|
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