Rebecca requests…On a recent trip to the beach I was unfortunate enough to sit down wind of someone applying a spray on sunscreen. I think less than half of what she sprayed actually hit her body because most of it was blown away by the breeze and landed on me! I could feel it and even see a fine film covering my sunglasses. I couldn’t help but wonder how in the world a spray on product can provide effective sun protection. Do the spray products use different ingredients than the lotions?
The Left Brain responds:
Formulating a spray-on sunscreen does present different challenges than creating a lotion product.
To start with, even thin emulsions are difficult to spray because they don’t atomize well and they can clog the valve. So, most spray products are solutions of UV absorbers in ethanol. That means only alcohol soluble ingredients like Avobenzone, Homosalate, Octisalate, Octocrylene, and Oxybenzone can be used. Physical sunblocks, like titanium dioxide and zinc oxide, are not alcohol soluble so they can’t be sprayed from this type of product. In addition, to help ensure that the sunscreen coats the skin evenly, film forming ingredients like Acrylates/Octylacrylamide Copolymer are added. These film formers helps keep prevent the alcohol solution from pooling in nooks and crannies of your skin.
Of course none of this matters if too much overspray occurs. If the spray doesn’t hit your skin it’s obviously wasted. While they are appealing because of ease of application you may be getting less deposition than you realize, especially if you’re applying them on a windy day. Considering how important uniform sunscreen application is for the prevention of sunburn (and potentially skin cancer), I think it’s a bit risky to rely on this kind of spray application.
Perhaps that’s why sprays are not “officially” approved as sunscreens even though they are sold as such. According to an article by Stanley B Levy, MD published Medscape, as of April 11, 2012, “The FDA Final Monograph has not approved sprays as a dosage form pending further considerations and testing.”
Furthermore, all that wasted over spray makes spray-on sunscreens potentially more expensive to use. And when you factor in the cost of ethanol (which is a more expensive solvent than water) and the aluminum can and the valve hardware (which are more expensive than a plastic lotion bottle), you may end up paying a lot more for the convenience of not getting lotion all over your hands. I think I’ll stick with lotions.
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